Citation
Tomato Packinghouse Wastewater

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Title:
Tomato Packinghouse Wastewater Characterization and Leaching Studies
Creator:
Chahal, Maninder
Place of Publication:
[Gainesville, Fla.]
Publisher:
University of Florida
Publication Date:
Language:
english
Physical Description:
1 online resource (103 p.)

Thesis/Dissertation Information

Degree:
Master's ( M.S.)
Degree Grantor:
University of Florida
Degree Disciplines:
Soil and Water Science
Committee Chair:
Toor, Gurpal Singh
Committee Members:
Nkedi-Kizza, Peter
Santos, Bielinski M.
Hochmuth, George J.
Graduation Date:
8/7/2010

Subjects

Subjects / Keywords:
Chlorides ( jstor )
Irrigation ( jstor )
Leaching ( jstor )
Soil science ( jstor )
Soil water ( jstor )
Soils ( jstor )
Tomatoes ( jstor )
Wastewater ( jstor )
Wastewater irrigation ( jstor )
Wastewater treatment ( jstor )
Soil and Water Science -- Dissertations, Academic -- UF
cations, contamination, leaching, metals, packinghouses, phosphorus, tomato, wastewater
Genre:
Electronic Thesis or Dissertation
bibliography ( marcgt )
theses ( marcgt )
government publication (state, provincial, terriorial, dependent) ( marcgt )
Soil and Water Science thesis, M.S.

Notes

Abstract:
As a result of urbanization, tomato packers in Florida often struggle to find ways to reuse the large volumes of wastewater generated during the tomato cleaning and sanitizing process. High transportation costs for off-site disposal and strict surface water discharge regulations are critical issues associated with the management of packinghouse wastewater in Florida. Information about the composition of packinghouse wastewater, likely sources of major wastewater constituents, and effects of land application might provide insights to develop environmentally sustainable practices for reuse of wastewater. The objectives of this study were to (1) characterize wastewater produced in tomato packinghouses and (2) evaluate the leaching potential of phosphorus and trace metals added with wastewater in the sandy soils typical in Florida. Results showed that wastewater had high electrical conductivity (1.3?2.8 dS/m) and chloride (255?1125 mg/L) due to the use of chlorine gas as a sanitizer in the packinghouses. Concentrations of phosphorus (2.8?5.7 mg/L) and copper (1.9?2.2 mg/L) in wastewater increased during the tomato cleaning and sanitizing process. The wastewater concentrations were above the threshold limits of 0.74 mg/L for phosphorus discharge in Tampa Bay watershed area and 0.03?0.5 mg/L for copper discharge in groundwater supplies and irrigation water in agriculture. Analysis of leachate collected from packed soil columns (50 cm long x 30 cm diameter) irrigated with wastewater at three different application rates for 30 days (0.84, 1.67, 2.51 cm/day) showed that soil acted as a sink for phosphorus, copper, manganese, sodium, and potassium whereas calcium, magnesium, iron, and zinc applied with wastewater were not retained and were vertically transported to a depth of 50 cm. The high ionic strength (0.031 moles/L) and high sodium adsorption ratio (10.8) of wastewater resulted in phosphorus and sodium adsorption in the soil. The application of wastewater at medium rate (1.67 cm/day) did not affect leaching behavior of phosphorus, copper, and iron whereas calcium, magnesium, potassium, manganese, and zinc losses were increased by 2?7 times as compared to the control. Application of wastewater at the high rate (2.51 cm/day) increased the leaching losses of phosphorus and all metals by 1.3?3 times. This result suggested that the long term application of wastewater at high rate can increase the leaching of phosphorus and trace metals and can potentially cause groundwater contamination. However, our results showed that packinghouse wastewater can be safely applied at sandy soils at 1.67 cm/day without significant concern of increased phosphorus and copper leaching. ( en )
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (M.S.)--University of Florida, 2010.
Local:
Adviser: Toor, Gurpal Singh.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2011-08-31
Statement of Responsibility:
by Maninder Chahal.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Embargo Date:
8/31/2011
Resource Identifier:
004979980 ( ALEPH )
707467083 ( OCLC )
Classification:
LD1780 2010 ( lcc )

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Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

TOMATO PACKINGHOUSE WASTEWATER: CHARACTERIZATION AND LEACHING
STUDIES

By

Maninder Kaur Chahal

August 2010

Chair: Gurpal Toor
Major: Soil and Water Science

As a result of urbanization, tomato packers in Florida often struggle to find ways to reuse

the large volumes of wastewater generated during the tomato cleaning and sanitizing process.

High transportation costs for off-site disposal and strict surface water discharge regulations are

critical issues associated with the management of packinghouse wastewater in Florida.

Information about the composition of packinghouse wastewater, likely sources of major

wastewater constituents, and effects of land application might provide insights to develop

environmentally sustainable practices for reuse of wastewater. The objectives of this study were

to (1) characterize wastewater produced in tomato packinghouses and (2) evaluate the leaching

potential of phosphorus and trace metals added with wastewater in the sandy soils typical in

Florida. Results showed that wastewater had high electrical conductivity (1.3-2.8 dS m-') and

chloride (255-1125 mg L-) due to the use of chlorine gas as a sanitizer in the packinghouses.

Concentrations of phosphorus (2.8-5.7 mg L-) and copper (1.9-2.2 mg L-) in wastewater

increased during the tomato cleaning and sanitizing process. The wastewater concentrations were

above the threshold limits of 0.74 mg L-1 for phosphorus discharge in Tampa Bay watershed area

and 0.03-0.5 mg L-1 for copper discharge in groundwater supplies and irrigation water in

agriculture. Analysis of leachate collected from packed soil columns (50 cm long x 30 cm









sorption rates in soil. In a solution like our wastewater which has the variable concentrations and

charge of ions such as Ca, Mg, Fe, and K, an increase in ionic strength (0.031 mol L-1) can

increase the net surface charge (surface potential) in the soil (Pardo et al., 1992). As a result, the

infiltration of high ionic strength wastewater in soil increased the sorption of P onto the surface

of soil colloids. In addition to wastewater properties, soil native adsorbents such as presence of

Fe/Mn and Al oxides, organic matter, and CaCO3 can sorb P in the soil as suggested by Chen et

al. (2003). This suggested that high Al (1284-1701 mg kg-1), Fe (454-446 mg kg-1) and Ca

(89-517 mg kg-') in our soil may be the most active adsorption sites of wastewater applied P.

Leachate concentration of Na was < 0.4 mg L-1 in the control treatment (Figure 3-4).

Similarly, in wastewater treatments, leachate Na concentration was low only in phase 1 (0.6-0.8

PV) which was the pre-event water. This indicated that no water soluble Na was leached from

the soil which can be due to low water soluble contents (3-4 mg kg-') of Na in soil as compared

to other dominant cations (Ca, Mg, and K) having water soluble contents of 4-46 mg kg'1 (Table

3-5). This resulted in low Na exchangeable percentage (0.21-0.36%) in soil which means that

most of the Na in soil was in non-exchangeable form. Secondly, the dilution factor in soil

columns was also low as total amount of de-ionized water added (36.6 L or 3.3 PV in control)

during 30 leaching events was not sufficient to extract water-soluble Na from the soil weighing

67 kg of mass (-2:1 soil water ratio). In phase 2, leachate Na gradually increased to 184 mg L-1

at 1.3 PV in low, and 316-334 mg L-1 at 2 PV in medium and high treatments. The increase in

leachate Na during this period (phase 2) indicates the appearance of a part of wastewater in the

leachate along with some pre-event water. During phase 3 (> 2 PV), Na concentration was

constant in wastewater treatments (335+20 mg L-1) similar to chloride breakthrough curves

suggesting that flow of Na rich wastewater in the soil also increased Na concentration in the









and the depth to the restrictive layer (Bh horizon) is more than 200 cm (USDA-NRCS, 2009b).

The soil at the site was zolfo fine sand series (sandy siliceous, hyperthermic oxyaquic alorthods)

which is the second most dominant series (7% of total area) in the study area (Hillsborough

County) after Myakka series (USDA-NRCS, 2009a). In the past, the site was under citrus

cultivation while for last 10 years, the site was not under cultivation. Soil samples were collected

from two distinct horizons: 1) Ap: disturbed surface soil horizon ranging from 0 to 17 cm, and 2)

A/E: transition subsurface horizon ranging from 17 to 50 cm. The collected soil samples were

separately air-dried for about 1-2 weeks and then manually sieved using a 2-mm sieve (US

sieve No. 10). A sub-sample was taken from each of the two horizons and was retained to

determine physical and chemical properties of soils.

Column Preparation, Setup, and Equilibration

Soil columns were built by cutting a 30-cm internal diameter polyvinyl chloride (PVC)

pipe into 50-cm long section (total surface area: 730 cm2) using a modification of the

methodology developed by Maguire and Sims (2002) to study P leaching in soils. In each PVC

column, about 45 kg of air-dried and sieved soil from A/E horizon was packed in lower 17-50

cm of soil columns to achieve the measured field bulk density of 1.87 g cm-3. About 23 kg of soil

from A horizon was packed in top 0-17 cm of soil columns to achieve the measured field bulk

density of 1.77 g cm-3. To achieve these field bulk densities, packing of both horizons was done

in 5-cm increment depth as suggested by other researchers (Ashworth et al., 2008; Funderburg et

al., 1979; Gao and Trout, 2006; Mamo et al., 2005; Park et al., 2002). After each 5-cm increment

addition in the column, soil was tapped for 3-min to ensure uniform packing before adding next

increment of soil.

Each column had an end cap at the bottom (Figure 3-1). To prevent sand loss in leachate

with irrigation, a section of the cheesecloth was placed at the bottom of each end cap. The end

45







bicarbonate may transfer Zn and K residues to the wastewater. In addition, residues of foliar-

applied Cu and Zn as micronutrient in plants may also be a likely source of wastewater Cu and

Zn.

As tomato beds in Florida are covered with a plastic sheet, there is a neglegible risk of soil

particles deposition on tomato plants. However, the splashing effect of frequent rain on the

exposed soil, in between covered beds, can potentially contaminate some of the tomato fruits, or

foliage with soil particles immediately or during harvesting. During the wastewater sample

collection period (May-June, 2009), total rainfall observed in the study area was relatively high

(>30 cm) which may have caused fruit contamination due to splashing of soil particles. The bins

used in tomato fields to pick up harvested tomatoes may contaminate the produce with soil

particles to some extent from previous loads. In Florida, the macronutrients such as P and K are

either directly incorporated in soil or applied with irrigation water in the crop root zone. The

foliar sprays of P and K are not preferred as the leaves cannot absorb sufficient quantities of

these nutrients (without burning) to correct their deficiency in plants or soil. Therefore, some of

the applied P and K can be accumulated in soil and thus, deposition of eroded soil particles

(containing P and K) on tomato fruits and foliage may contaminate the water which comes in

their contact during the washing operations. However, we do not have information whether soil

particles contributed any of these metals to wastewater

In two packinghouses, significant correlation of coefficient values of 0.41-0.63 between

amounts of washed tomatoes and chemical constituents such as P and Cu in wastewater indicated

that tomatoes can explain about half of the variability in P and Cu concentrations except for Zn

in PKG 2. In addition to external factors (amounts of washed tomatoes), wastewater internal

factors (chloride or pH) may also result in elevated concentrations of these constituents (P, Cu,

and Zn) in wastewater. Therefore, the stepwise linear regression equations were developed to









CHAPTER 5
SUMMARY, CONCLUSIONS, AND RECOMMENDATION

Florida is the single largest producer of fresh-market tomatoes in US. About 70 tomato

packinghouses in Florida pack these tomatoes for domestic market and generate 231 million L of

wastewater each year. Tomato industry in Florida is facing the dilemma of sustainably managing

large amounts of wastewater produced in tomato packinghouses. Because of rapid urbanization,

lack of wastewater disposal sites near packinghouses, and strict Florida surface water discharge

regulations, most (54%) of the wastewater generated is disposed in agricultural soils (Florida

Tomato Committee, 2007). Since, most of the Florida soils are coarse textured, have low organic

matter and shallow groundwater table, land application of packinghouse wastewater in sandy

soils may pose a risk of phosphorus (P) and trace metal leaching to the groundwater. Thus, we

characterized the wastewater produced during sanitizing operations in tomato packinghouses to

identify the elements of concern and evaluated their leaching potential in a typical sandy soil of

Florida during land application.

Our methodology included collection of wastewater samples at 30-min intervals from the

dump tanks in two representative tomato packinghouses and analysis of wastewater samples for

P and trace metals. Wastewater pH was in the normal range (6.5-8) as suggested for Florida

packinghouse waste stream (Bartz et al., 2009) while electrical conductivity (EC) and chloride

were high in our wastewater as compared to Florida surface water discharge guidelines (Florida

Administrative Weekly, 2006). The chlorine use for sanitization of tomatoes in the dump tanks

resulted in increased concentration of chloride in the wastewater and thus EC. About 4.5 times

higher chloride were observed in one packinghouse than other while pathogen loads in both

packinghouse were similar (Bonilla and Toor, 2010), suggesting that the chlorine use in waste

streams needs to be reduced. This will directly benefit packinghouses due to reduced cost of









A
y


Changes in water quality in the dump tank during cleaning of tomatoes in a tomato
packinghouse: (A) clean water is added to dump tank before beginning of packing
operation, (B) tomatoes are cleaned and sanitized, and (C) wastewater is produced
at end of the day.


Figure 1-2.









CHAPTER 4
LEACHING OF TRACE METALS IN A SANDY SOIL IRRIGATED WITH WASTEWATER

Introduction

Biogeochemical cycling of trace metals among soil, plants, water, and even atmosphere is

affected by several factors that are both natural and anthropogenic (Tijani, 2009). Anthropogenic

activities such as atmospheric deposition from industrial sites, waste disposal or incineration,

urban wastewater, traffic emission, fertilizer use, and long-term applications of wastewater in

agricultural lands are known to be the important contributors of elevated concentrations of

copper (Cu), cadmium (Cd), lead (Pb), and zinc (Zn) in the soils (Koch and Rotard, 2001;

McLaughlin et al., 2000). The application of wastewater at agronomic rates can provide essential

nutrients for plant growth and reduce pressure on ground and surface water for meeting irrigation

needs. However, presence of excess amounts of trace metals in some wastewaters can adversely

impact soil and water quality (Bradford et al., 2008). For instance, 50-day application of

industrial wastewater containing 12 mg Cu L-1 in loamy clay paddy fields resulted in 6 times

greater accumulation of Cu (101 mg kg-1) than the control soil (17 mg kg-1) in the surface soil

(0-40) cm and caused 18-25% decrease in crop yields in wastewater irrigated paddy fields (Cao

and Hu, 2000). Similarly, Nayek et al. (2010) reported that application of metal enriched

industrial wastewater (iron ( Fe): 0.8, Cu: 0.73, Manganese (Mn): 0.73, and Zn: 0.7 mg L-) in a

surface (0-10 cm) lateritic soil (Fe rich) resulted in 2-3 times more accumulation (Fe, Mn, Zn,

Cu: 258, 212, 176, and 122 mg kg- respectively), than the control soil (Fe, Mn, Zn, Cu: 86, 87,

77, 66 mg kg- respectively). They noted that the accumulation of metals in the surface soil was

strongly correlated with organic matter and cation exchange capacity of soil. Tam and Wong

(1996) also observed 7, 3.5, and 3 times greater accumulation ofZn, Mn, and Cu, respectively in

packed soil lysimeter (70 cm long and 10 cm wide) irrigated with synthetic wastewater (Mn: 20









4-1 Pre-wetting/pre-event irrigation schedule in soil columns using de-ionized water
during July-A ugust 2009............................................................................. 85

4-2 Treatm ents applied in soil columns ............................................................................85

4-3 Selected properties of surface (0-17 cm) and subsurface (17-50 cm) soils in the
packed soil column ns .................. .................. ................. .......... .. .............. 85

4-4 Total and water extractable contents of trace metals (mg kg-1) in two soil horizons in
the packed soil column ns .......... ..... ............................................... .. 86

4-5 Trace metal concentrations of packinghouse wastewater applied in the soil columns......86

4-6 Mean leachate volume of 30 leaching events in control and wastewater irrigated soil
c o lu m n s ...................... .. .. ......... .. .. ..................................................... 8 6

4-7 Mean leachate concentrations (mg L-) of trace metals in four treatments in 30
leachin g ev ents ........................ .. ......... .. .. ................................................87

4-8 Total amounts of trace metals (Cu, Fe, Mn, and Zn) applied in the soil columns,
amounts leached, and percent leaching of applied amounts in four treatments in 30
leaching events ....................... ....... ..................................... ........... 87









Table 3-11. Guidelines for interpretation of water quality for irrigation purposes in agriculture
(Ayers and Westcot, 1989)
Potential irrigation problems Degree of restriction on use
None Slight to moderate Severe
pH Normal range = 6.5-8
EC (dS m-) <0.7 0.7-3 >3
Na (SARt) <3 3-9 >9
Chloride (mg L-1) <106 >106
Fe (mg L-) <1
t Sodium adsorption ratio









Table 3-4. Selected chemical properties of surface (0-17 cm) and subsurface (17-50 cm) soils in
the packed soil columns
Parameter Surface Subsurface
pH 60.08at 5.50.01b
EC (dS m-) 0.0653a 0.03911lb
Organic matter (g kg-') 231la 8+lb
Elements (mg kg-1)


Ca
Fe
P
Mg
K


128439b
51715a
45423a
2686a
753a
5921a


170165a
891b
44619a
1869b
403b
232b


Na 156a 10+la
tMeanstandard deviation
Values followed by same letters in a row are not significantly different at P<0.05 using Fishers
LSD.


Table 3-5. Water-extractable (soil to water ratio=
packed in the soil columns


1:10) elements (mg kg-1) in two soil horizons


Elements Surface (0-17 cm) Subsurface (17-50cm)
MeanSDt % of total MeanSD % of total
contents contents
Ca 4620a 9 18+1a 20
K 16+la 27 40.4b 17
Al 132b 1 4314a 3
Mg 12+la 17 60.9b 14
P 12+la 4 142a 8
Na 40.5a 27 3+la 33
Fe 4+0.6b 1 1+ 4a 3
t Standard deviation
Values followed by same letters in a row are not significantly different at P<0.05 using Fishers
LSD.









analyzed for 5 trace metals by ICP-OES. Wastewater and leachate pH and EC were measured by

using above digital meter. Chloride in wastewater and leachate was determined using a discrete

analyzer (AQ2+, Seal Analytical Inc, Mequon, WI). The 4 trace metals (Cu, Fe, Mn, and Zn) in

all wastewater and leachate samples were analyzed using above ICP-OES.

Statistical Analysis

Basic statistics including mean, standard deviation, range, and coefficient of variation of

parameters in leachate samples were performed in Microsoft Excel 2007. Mean concentration

(mg L-) of each element was multiplied with leachate volume to calculate loads. Significant

differences in concentrations and loads among control and three wastewater treatments were

determined using least significant difference (LSD) method at P <0.05 using PROC GLM

procedure in SAS statistical analysis (SAS Institute, 2007).

Results and Discussion

Physical and Chemical Properties of Soils

Soil in our study was sandy in nature (>92% sand) with very low clay content (<0.4%)

(Table 4-3). Surface horizon had lower bulk density and particle density than subsurface horizon

while porosity was similar in both horizons (28-31%). Surface soil also had significantly higher

pH, EC, and organic matter than the subsurface soil. Surface soil had significantly greater total

Cu, Zn, Mn, and Cr contents than subsurface soil while Fe contents did not vary significantly in

two horizons (Table 4-4). Water extraction recovery for different trace metals varied in two

horizons, with higher recovery of Fe, and Cu in subsurface (3-7.5%) than the surface soil (<2%)

while Zn recovery was similar in both horizons (2.5-3%). Water extractable Mn was 0.23% of

total in surface and below detection limit in subsurface soil.







HOCI + 2H+ +1.49 C- + H20

Cl2 + 2e- +1.36V 2C1

OCt +2H20+2e- +0.90 C + 20H

All chemical constituents showed a greater magnitude of increase in PKG 1 wastewater

than PKG 2 due to greater contact time of tomatoes with water which was 55-72 second in PKG

1 and 32-40 second in PKG 2 per 454 kg of dumped tomatoes (Table 2-4). Among all metals,

the greatest increase was observed for Cu whose concentrations increased from 0.01 mg L-' in

municipal water to 1.9-2.2 mg L-1 in wastewater. Among trace metals, Cu concentration was

above the threshold limit of 0.03 mg L-1 for grounwater discharge and 0.5 mg L-1 for irrigation

water in agriculture (Florida Administrative Weekly, 2006) while other trace metals such as Fe

and Zn were below the threshold limits of 1 mg L-1 for irrigation water. Therefore, wastewater

may need to be treated to remove Cu before discharging into city sewers.

Concentrations of P in wastewater increased from <0.27 mg L-1 to 2.8 (PKG 2) -5.7 (PKG

1) mg L-1. The concentration of P in our wastewater was similar to that of municipal wastewater

(2.5-6.5 mg L-) (Monclus et al., 2010) and potato processing wastewater (3.4 mg L1)

(Zvomuya et al., 2006) while Szogi & Vanotti (2009) reported relatively higher P in swine

lagoon wastewater (61 mg L-1). According to De Lange et al. (2001), less utilization of P by

swines, overfeeding, and feeder management can result in high P in the manure wastewater. The

higher P concentration in dairy (30 mg L-) and poultry (34 mg L-) lagoon wastewater (Bradford

et al., 2008) than the current study highlights the variability in different wastewater types due to

different sources. The relatively high P in our wastewater suggests that packinghouse wastewater

needs to be treated to remove P before it can be permitted to be discharged in surface water

bodies as the proposed EPA water quality total P limit is 0.74 mg L-1 for Tampa Bay streams

(EPA, 2010).


















o
2 0.9



S0.8



0~.7



0.6
=



1.0



S0.9



0.8
-


1 0.7
-



0.6
0


1.2


1.0


o 0.8
Q

- 0.6
C














U 0.4


0.2


0.0
0


I I I
.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume
-- Control Low -- Medium High


Leachate volume recovery and chloride breakthrough in soil columns during 30

leaching events: A) Plot of leachate to irrigation ratio with time, B) Plot of leachate
to irrigation ratio with pore volumes, and C) Chloride breakthrough curves showing

three phases where C is the leachate concentration and Co is the irrigation
concentration.


0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (days)
B


Figure 3-2.









treatment. This suggests that with increase in wastewater application, more Mn was retained in

the soil profile.

Summary

Application of wastewater at medium rate (1.67 cm per day) only increased concentration

of Zn at 50 cm depth while no significant effect was observed on Cu, Fe, and Mn concentrations.

Application of wastewater at high rate (2.51 cm per day) significantly increased the

concentration of Zn and leaching losses of Zn as well as Cu and Mn. A large percentage of the

applied Cu was adsorbed in the soil while Fe and Zn were desorbed from the soil. Since our soils

had low clay content, high Fe and organic matter in the surface soil may be the most important

adsorption sites for Cu and Mn. The removal of Fe and Mn from the soil may be due to the

enhanced mobility of reduced forms of these metals even in slight to moderate saturation

conditions imposed by daily irrigation. We found that medium rate of wastewater application did

not significantly affect mean concentration of Cu in the leachate in 30 leaching events but Zn

concentrations were elevated but were much below the drinking water limits of 1.3 mg L-1 for Cu

and 5 mg L-1 for Zn (USEPA, 2010) suggesting a minimum risk of groundwater contamination in

areas irrigated with wastewater. It should be noted that these leachate concentrations were

measured at 50 cm depth, which will further diminish with increase in soil depth, thus, there is

less possibility of these metals leaching to groundwater. However, concentrations of Fe and Mn

in the leachate were above 0.3 mg L- and 0.05 mg L-, respectively of the National Secondary

Drinking Water Regulation's non enforceable guidelines. Based on results of our study, we

suggest that packinghouse wastewater can be safely applied at 1.67 cm per day in most of the

sandy soils in Florida.









BIOGRAPHICAL SKETCH

Maninder Kaur Chahal was born in Ferozepur (Punjab), India. The youngest of three

children, she spent most of her life in Ferozepur. After her intermediates, she started her

bachelor's degree in Punjab Agricultural University, Ludhiana in 2004 and completed in 2008.

In June 2008, she started a master's program in the Department of Soil and Water Science under

the supervision of Dr. G. S. Toor at the Gulf Coast Research and Education Center-Wimauma,

University of Florida. Maninder received her master's degree from the University of Florida in

the summer 2010.


103









TABLE OF CONTENTS





A C K N O W L E D G M E N T S ..............................................................................................................4

LIST OF TABLES ......... ..... .... ....................................................7

LIST OF FIGURES .................................. .. ..... ..... ................. .9

L IST O F A B B R E V IA TIO N S......... ............. ............................................... ...................... 10

A B S T R A C T ................................ ............................................................ 12

CHAPTER

1 INTRODUCTION .................. .................. ................................ ............ 14

Tomato Production Trends in the United States.......................... ............... ............. 14
Water Use and Wastewater Production in Tomato Packinghouses................... ..........15
W astewater Suitability for Environm ental U se ............................. ................................... 15
Research Objectives.............................. .. .... ..... ..................16

2 WASTEWATER CHARACTERIZATION IN TOMATO PACKINGHOUSES .................20

Introdu action ................... ......................................................... ................. 2 0
M materials and M ethods ........................ ................. ................. ..22
Packing Operations in Packinghouses................................... ............................. ....... 22
W astew ater Sam ple Collection................................................ ............................ 23
Laboratory Analysis .................................. .. .......... ............... 24
Statistical A analysis ........................ .. .......................... .. .... ........ ........ 24
Results and Discussion ...................................................25
Amount of Tomatoes Packed in the Packinghouses............. ..... ............... 25
Chemical Characteristics of Municipal Water Used in Packinghouses ..........................25
Effects of Amounts of Tomatoes Packed on Wastewater EC and Chloride .................25
Effects of Amounts of Tomatoes Packed on Wastewater Chemical Constituents..........26
Factors Affecting Concentrations of P, Cu, and Zn in Packinghouse Wastewater .........28
Implications of Using Packinghouse Wastewater in the Environment ...........................30
S u m m a ry ................... ............................................................ ................ 3 3

3 LEACHING OF PHOSPHORUS AND CATIONS IN A SANDY SOIL IRRIGATED
WITH PACKINGHOUSE WASTEWATER.....................................................................41

Introdu action ................... ......................................................... ................. 4 1
M materials and M ethods ..................................... .. .. .. ........ .. ............44
Study Site and Sam ple Collection ............................................................................. 44






































Figure 3-1. Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse: A)
cheesecloth fixed at the bottom of an end cap, B) end caps filled with sand and
gravels, C) and D) packed soil columns.









(Wenzel et al., 1997). In addition, porous cups have been speculated to have an inherent bias in

preferentially monitoring the chemical composition of macropores at the expense of micropores

(Weihermuller et al., 2007). Similarly, the use of field drainage systems can be problematic due

to lack of control over the environmental conditions such as temperature and humidity at the

installation site. Monolith lysimeters which provide a well defined boundary with one dimension

vertical flow are widely accepted for accurate determination of solute transport in undisturbed

soils (Chardon et al., 2007; Jabro et al., 2001; Jensen, 1994; Malone et al., 2004). As most of the

soils in Florida are coarse textured and lack soil structure, which will make it nearly impossible

to obtain intact soil columns, the use of soil lysimeters with homogenized packing can be a good

approach for conducting the leaching studies. In addition, wastewater contaminant losses via

preferential flow can be avoided in homogeneous soil conditions because of the uniform packing

which can otherwise occur in structured monolith lysimeters via macro-pores (Gjettermann et al.,

2009; Malone et al., 2004).

Long term land application of liquid waste has been shown to increase the soil P levels

(Johnson et al., 2004), therefore, in order to be sustainable, these practices must consider the fate

and transport of P to groundwater. As liquid wastes contain a diverse mix of various metals that

may either leach from or be retained in the soil structure by chemical reactions or can be taken

up by plants depending upon the soil type, wastewater properties, and irrigation amounts. For

instance, Barton et al. (2005) reported that 2-year application of domestic wastewater containing

5.8 mg total P L-1 in intact clay loam lysimeters (0.46 m wide and 0.7 m deep) resulted in 16%

leaching of the applied P. They attributed higher P leaching in the clay loam soil to low P uptake

by plants. Similarly, Zvomuya et al. (2005) observed that the application of potato processing

wastewater (3.6 mg L-1 total P) in intact sandy loam lysimeters (0.3 m wide and 1.5 m long)









Johnson, A.F., D.M. Vietor, F.M. Rouquette, Jr., and V.A. Haby. 2004. Fate of phosphorus in
dairy wastewater and poultry litter applied on grassland. J. Environ. Qual. 33:735-739.

Kang, C., S. Sim, Y. Cho, and W. Kim. 2003. Process development for the removal of copper
from wastewater using ferric/limestone treatment. Korean J. Chem. Eng. 20:482-486.

Khattack, R.A., and A.L. Page. 1992. Mechanism of manganese adsorption on soil constituents,
p. 383-400, In D. C. Adriano, ed. Biogeochemistry of trace metals. Lewis Publ., Boca
Raton, FL.

Kleinman, P.J., M.S. Srinivasan, and A.N. Sharpley. 2005. Phosphorus leaching through intact
soil columns before and after poultry manure application. Soil Sci. 170:153-166.

Koch, M., and W. Rotard. 2001. On the contribution of background sources to the heavy metal
content of municipal sewage sludge. Water Sci. Technol. 43:67-74.

Leal, R.M.P., U. Herpin, A.F.d. Fonseca, L.P. Firme, C.R. Montes, and A.J. Melfi. 2009.
Sodicity and salinity in a Brazilian Oxisol cultivated with sugarcane irrigated with
wastewater. Agr. Water Manage. 96:307-316.

Lewis, W.M. 1995. Wetlands:characteristics and boundaries, San Diego, CA.

Lin, C., I. Negev, G. Eshel, and A. Banin. 2008. In situ accumulation of copper, chromium,
nickel, and zinc in soils used for long-term waste water reclamation. J. Environ. Qual.
37:1477-1487.

Madrid, L., and E. Diaz-Barrientos. 1998. Release of metals from homogeneous soil columns by
wastewater from an agricultural industry. Environ. Pollut. 101:43-48.

Magesan, G.N., J. Dalgety, R. Lee, J. Luo, and A.J. van Oostrom. 1999. Preferential flow and
water quality in two New Zealand soils previously irrigated with wastewater. J. Environ.
Qual. 28:1528-1532.

Maguire, R.O., and J.T. Sims. 2002. Soil testing to predict phosphorus leaching. J. Environ.
Qual. 31:1601-1609.

Malone, R.W., M.J. Shipitalo, R.D. Wauchope, and H. Sumner. 2004. Residual and contact
herbicide transport through field lysimeters via preferential flow. J. Environ. Qual.
33:2141-2148.

Mamo, M., S.C. Gupta, C.J. Rosen, and U.B. Singh. 2005. Phosphorus leaching at cold
temperatures as affected by wastewater application and soil phosphorus levels. J. Environ.
Qual. 34:1243-1250.

Mapanda, F., E.N. Mangwayana, J. Nyamangara, and K.E. Giller. 2005. The effect of long-term
irrigation using wastewater on heavy metal contents of soils under vegetables in Harare,
Zimbabwe. Agric. Ecosyst. Environ. 107:151-165.







amount of tomatoes will be slower for tomatoes dumped at 60 than 30 second intervals in the

dump tank. Each day, the dumping rate in packinghouse is adjusted manually to accommodate

the degree of sorting and grading for each lot of tomatoes at the packing counter. In addition,

clean water was sometimes added during the operations to compensate the water loss due to

spillage. To avoid the cross-contamination of pathogens during washing in the dump tank,

sanitizers such as chlorine gas, are constantly added in the water to maintain at 150-200 mg L-

1of free chlorine in the waste stream at water pH of 6.5 to 7.5 (Bartz et al., 2009). The packing

operation typically lasts 6 to 8 h in a day.

Wastewater Sample Collection

Wastewater samples from two major tomato packinghouses (hereafter referred to PKG 1

and PKG 2) were collected during May-June 2009, which refers to the packing season of

tomatoes grown in Jan-April 2009. In both packinghouses, typical operational time of tomato

packing varied from 6 (PKG 2) to 8 (PKG 1) h. The variability in operational hours is due to the

variable amounts of tomatoes that need packing on a given day and allocation of different lots of

tomatoes with variable size and quality from different growers that require different flow time in

the waste stream. For each of the two packinghouses, four sampling events (referred to as S-1,

S-2, S-3, and S-4) were conducted on a weekly basis during May-June 2009. During each

sampling event, municipal water or fresh water samples were collected from the dump tanks in

250 mL plastic bottles before the beginning of packing operations. After the start of packing

operations, wastewater samples from the end of the water stream were collected at 30-min

intervals for about 6-8 h. The collected samples were chilled on ice, brought to the laboratory,

and analyzed. The amounts of tomatoes packed in each 30-min interval were calculated by

recording the rate of dumping i.e. time taken to wash one bin that contained 454 kg of tomatoes

throughout the packing day.


















o
2 0.9



S0.8



0~.7



0.6
=



1.0



S0.9



0.8
-


1 0.7
-



0.6
0


1.2


1.0


o 0.8
Q

- 0.6
C














U 0.4


0.2


0.0
0


I I I
.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume
-- Control Low -s- Medium -- High


Leachate volume recovery and chloride breakthrough in soil columns during 30

leaching events: A) Plot of leachate to irrigation ratio with time, B) Plot of leachate
to irrigation ratio with pore volumes, and C) Chloride breakthrough curves showing

three phases where C is the leachate concentration and Co is the irrigation
concentration.


0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30
Time (days)
B


Figure 4-2.









methodology developed by Maguire and Sims (2002) to study phosphorus (P) leaching in soils.

In each PVC column, about 45 kg of air-dried and sieved soil from A/E horizon was packed in

lower 17-50 cm of soil columns to achieve the measured field bulk density of 1.87 g cm-3. About

23 kg of soil from A horizon was packed in top 0-17 cm of soil columns to achieve the

measured field bulk density of 1.77 g cm-3. To achieve these field bulk densities, packing of both

horizons was done in 5-cm increment depth as suggested by other researchers (Ashworth et al.,

2008; Funderburg et al., 1979; Gao and Trout, 2006; Mamo et al., 2005; Park et al., 2002). After

each 5-cm increment addition in the column, soil was tapped for 3-min to ensure uniform

packing before adding next increment of soil.

Each column had an end cap at the bottom (Figure 4-1). To prevent sand loss in leachate

with irrigation, a section of the cheesecloth was placed at the bottom of each end cap. The end

cap was then packed up to 5-cm depth with a mixture of washed sand and gravels. After

packing, each end cap was securely attached to the bottom of PVC column and sealed with a

sealant to prevent water leakage, if any. A hole was drilled at the center of the end cap to which a

plastic pipe was attached to collect leachate in 2 L amber glass bottles. All the packed soil

columns were placed in the greenhouse at controlled temperature of 30-35 C (Figure 4-1) to

ensure similar experimental conditions for the duration of the experiment.

The soil columns were equilibrated by first wetting the soil with de-ionized water

equivalent to about 1 pore volume (PV) of soil (15 cm water depth or 11.1 L in each column) to

remove any air bubbles, if entrapped, during the packing of soil columns and to ensure

homogeneous moisture in all columns for subsequent experiments. Soil columns were left to

freely drain for few days and then were wetted by adding de-ionized water equivalent to a total

of 0.8 PV (11.69 cm water depth) in 1.67 cm per day increments for 7 days. The wetting events









Packinghouse 1


Packinghouse 2


70

65

60

55

50

S45

40

35

30

28

26

24

22

' 20

18

16

14


70

60

50

- 40

S30

20

10

0


Figure 2-4. Effect of cumulative amounts of washed tomatoes on wastewater Ca, Mg, and K
during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009.


70

65

60

55

50

45

40

35

.-. 30
0 50 100 150 200 250 300 350 0 50 100 150
28

26

24

22

20

18

16

.. 14
0 50 100 150 200 250 300 350 0 50 100 150
70

60

50

40

30

20

10

0
0 50 100 150 200 250 300 350 0 50 100 150
Tomatoes washed (Mg)

-- S-1 -0- S-2 S-3 --- S-4


200 250 300



















200 250 300


200 250









LIST OF ABBREVIATIONS


Al Aluminum

As Arsenic

B Boron

Ca Calcium

Cd Cadmium

Co Cobalt

Cr Chromium

Cu Copper

EC Electrical conductivity

FDEP Florida Department of Environmental Protection

Fe Iron

ICP-OES Inductively coupled plasma-optical emission spectroscopy

K Potassium

LI Leachate irrigation

LSD Least significant difference

Mg Magnesium

Mn Manganese

Mo Molybdenum

N Nitrogen

Na Sodium

Ni Nickel

P Phosphorus

Pb Lead

PKG 1 Packinghouse 1









Soil and Water Analysis

Soil samples from both horizons were analyzed for sand, silt, and clay using hydrometer

method (Day, 1965). Field bulk density of undisturbed soil cores was determined as described in

Blake and Hartge (1986) by collecting samples at 5-cm depth intervals beginning from 0 to 50

cm. Particle density of soil horizons was measured using Pycnometer method of Blake and

Hartge (1986). Using the bulk density and particle density of soil samples, porosity of each soil

horizon was calculated according to following equation.


Porosity (%) = 1 Bulk x 100
SParticle density

Soil pH was measured by equilibrating 10-g of soil with 20-mL of de-ionized water (1:2)

for 1-h with a digital meter (Accumet XL60, Dual channel pH/ion/conductivity/dissolved

oxygen meter, Fisher Scientific, Pandan Crescent, Singapore). The electrical conductivity (EC)

of soil samples was measured using a soil to de-ionized water suspension (1:1) with the same

digital meter. Total soil organic matter was determined by the oxidation method of Walkley and

Black (1934). Total trace metals including arsenic (As), boron (B), Cd, cobalt (Co), chromium

(Cr), Cu, Fe, Mn, molybdenum (Mo), nickel (Ni), Pb, selenium (Se), and Zn were extracted from

soils, in triplicates, using HNO3 and H202 (USEPA method 3050, 1996) followed by analysis on

inductively coupled plasma-optical emission spectroscopy (ICP-OES) (PerkinElmer Optima

2100 DV; PerkinElmer, Shelton, CT). Among 13 trace metals analyzed in soils, only 5 trace

metals (Cr, Cu, Fe, Mn, and Zn) were above the method detection limit of 0.02, 0.025, 0.3, 0.05,

and 0.02, respectively. Water extractable contents of detectable 5 trace metals (Cr, Cu, Fe, Mn,

and Zn) were measured by extracting 4-g of air-dried soil with 40-mL of de-ionized water (1:10

soil to water ratio) in a reciprocating shaker for 2-h followed by centrifugation at 4000 rpm for

20-min. The solution was then filtered through 0.45-lm membrane filter paper and filtrate was















0.35


0.30 0.
0.8

0.25
0.6

0.20

0.4
0.15
Wastewater cone.
0.2 0.16 mg L-1
0.10


0.05 .------- 0.0
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0


4.5 1.0
F Iron Manganese
4.0

3.5 0.8

3.0
0.6 -
2.5

2.0 4 wastewate cone.
Wastewater cone. 0.4 0.34 mg -1
1.5 0.44 mg L-1
1.5

1.0 0.2

0.5

0.0 0.0 .. .
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Leachate pore volume

-4- Control-- 0.5 FDEP-o-- 1.0 FDEP --- 1.5 FDEP


Figure 4-3. Mean concentration of trace metals in the leachate in four treatments during 30

leaching events in soil columns.



























90









using chlorine gas while also minimizing chloride and higher EC in the resulting wastewater.

The total P concentration in the wastewater was much greater than the proposed numeric total P

value of 0.74 mg L-1 for the Tampa Bay streams (EPA, 2010), which implies that this wastewater

needs to be treated before discharging to surface waters. Among trace metals, copper (Cu)

concentration in the wastewater was above the threshold limit of 0.5 mg L-1 for surface water

discharge (Florida Administrative Weekly, 2006) while other trace metals such as iron (Fe), and

zinc (Zn) were below the threshold limits of 1 mg L-1. If wastewater needs to be surface

discharged in those areas where sufficient land is not available for land irrigation, the wastewater

can be treated with chemical amendments such as aluminum chloride (alum), ferric chloride, and

calcium sulfate (lime), to precipitate P and Cu from the wastewater (Ebeling et al., 2006; Gray,

2005; Kang et al., 2003). The biological nutrient removal is another effective approach to

remove P from the wastewater; however as amount of wastewater generated in packinghouse is

limited, it may not be a cost effective approach. These recommendations are the potential

alternatives that can be used to treat wastewater if surface discharge is the only possible

alternative.

In our study, we evaluated the leaching potential of P and trace metals such as Cu, Zn, Fe,

and manganese (Mn) in a typical soil of Florida using soil columns. We packed 12 soil columns

in two distinct horizons (Ap and A/E) with variable irrigation rates or treatments: (1) control:

1.67 cm per day irrigation, (2) Medium: 1.67 cm per day irrigation, (3) High: 2.5 cm per day

irrigation, and (4) Low: 0.87 cm per day irrigation. The 1.67 cm per day was the application rate

suggested by the Florida Department of Environmental Protection for the safe disposal of

packinghouse wastewater (FDEP, 2009). All the packed soil columns were irrigated for 30 days

during August-September, 2009 in 4 above treatments and leachate were collected following the







<1 dS m-1 and <200 mg L-1 in PKG 2 wastewater after washing 50 Mg of tomatoes. The increase

in EC and chloride in both packinghouses was attributed to the use of sanitizers such as chlorine

dioxide and chlorine gas in the dump tanks. In PKG 1, after 200 Mg of tomatoes were washed in

S-4, EC and chloride in the wastewater increased at relatively higher rate during the last 2 h

which may be due to the change in type of tomatoes from Roma to round in the dump tanks.

Overall, EC and chloride trends showed much less variability among four sampling events in

PKG 2 than PKG 1. This may be due to more controlled conditions in PKG 2 than in PKG 1. For

instance, in PKG 1, chlorine gas in the water stream were manually added from pressurized gas

cylinders depending upon pH and oxidation-reduction potential. Measurements of chlorine

concentrations and water pH were also taken manually on an hourly basis to verify proper

functioning of operations. However, in PKG 2, chlorine dioxide addition was automated in the

water stream to maintain the optimum water pH (6.5-7.5). In addition, more breaks or stops in

the washing operations due to technical problems in dumping machine, crowding of tomatoes at

the packing counter and/or shifting of tomatoes from small-sized Roma to large-sized round

observed in PKG 1 may have also contributed to greater variability in EC and chloride than PKG

2.

Effects of Amounts of Tomatoes Packed on Wastewater Chemical Constituents

Concentrations of P, Cu, Zn, and Fe in wastewater increased as more tomatoes were

washed in two packinghouses (Figure 2-3). As with EC and chloride, P, Zn, and Fe

concentrations showed a similar pattern of greater concentrations and more variability during

four sampling events in PKG 1 than in PKG 2 while magnitude and variability of Cu increase

was similar in two packinghouses. Concentration of Zn in the wastewater was greater in PKG 1

than PKG 2 during all sampling events and the magnitude of increase in Zn concentrations was

more pronounced in the former than latter packinghouse. Wastewater Zn concentration increased







Time interval (minutes)
Amount of tomatoes packed (kg) = xme interval 454
Rate of dumping (minutes per 454 kg of tomatoes)

Laboratory Analysis

About 100 mL of wastewater sample was preserved for P and trace metals using cone.

H2SO4 to pH <2 and stored at 40C until analysis. The remaining 150 mL of unpreserved sample

was left on shelves until they attained room temperature. Then, pH and electrical conductivity

(EC) in unpreserved samples were measured using a digital meter (Accumet XL 60, Dual

channel pH/ion/conductivity/dissolved oxygen meter, Fisher Scientific, Pandan Crescent,

Singapore). Chloride in the wastewater was determined using a discrete analyzer (AQ2+, Seal

Analytical Inc, Mequon, WI). Total P and 18 metals including aluminum (Al), arsenic (As),

boron (B), calcium (Ca),cadmium (Cd), cobalt (Co), Cr, Cu, Fe, potassium (K), magnesium

(Mg), Mn, molybdenum (Mo), sodium (Na), Ni, P, lead (Pb), selenium (Se), and Zn in the

wastewater samples were determined using inductively coupled plasma-optical emission

spectroscopy (ICP-OES) (PerkinElmer Optima 2100 DV; PerkinElmer, Shelton, CT) (USEPA

method 200.7, 1985). Among 18 trace metals, 11 metals (Al, As, B, Cd, Co, Cr, Mo, Mn, Ni, Pb,

and Se) were below the detection limits of ICP-OES and therefore are not reported.

Concentrations of Na were typically between 16 to >50 mg L-1 in the wastewater.

Statistical Analysis

Mean, standard deviation, and range for the concentration of different parameters in

wastewater samples were calculated in Microsoft Excel 2007. Correlation matrix was established

between the different constituents at 0.05 probability level using DATA analysis program in

Microsoft Excel. Simple and stepwise linear regression was performed using Statistix version 8.0

software with LINEAR MODELS procedure.







with slope <0.001 in four sampling events while in PKG 2, slope of Zn increase was relatively

low (<0.0003) which indicated that even with an increase in number of tomatoes washed,

concentration of Zn in the wastewater remained almost constant in PKG 2. The concentrations of

Fe in the wastewater were more variable and greater during four sampling events in PKG 1 than

in PKG 2. Greater contact time of tomatoes with water in PKG 1 (55-72 seconds) than in PKG 2

(29-40 seconds) may have resulted in greater concentrations of constituents in PKG 1

wastewater.

Similarly, concentrations of Ca, Mg, and K in the wastewater increased as more tomatoes

were washed in all sampling events in two packinghouses (Figure 2-4). In PKG 1, wastewater Ca

increased linearly with relatively higher slope (0.15) in S-2 than other 3 sampling events

(0.05-0.07). However in PKG 2, a linear increase in Ca concentration was observed only at the

beginning when 25-62 Mg of tomatoes were washed in the dump tanks in all sampling events

except S-2 where Ca concentration continued to increase gradually till 200 Mg of tomatoes were

washed. Thereafter, Ca concentration increased from -40 to >50 mg L-1 at relatively higher

slopes as 276 Mg of tomatoes were washed. Concentrations of Mg and K were greater in PKG 1

than PKG 2 while in PKG 2, there was less variability during four sampling events than PKG 1.

For instance, in PKG 1, the slope of Mg increase in four sampling events varied from 0.02 in S-1

to 0.04 in S-2 while in PKG 2, slope of Mg increase was about similar in all sampling events

(0.02) with lower concentrations than PKG 1. In case of wastewater K, the slope of increase

varied from low (0.08-0.1) in S-1 and S-3 to relatively high (0.2) values in S-2 and S-4 events in

PKG 1. While in PKG 2, slope of increase was about similar with mean slope of 0.07 with

concentrations lower than PKG 1 indicating the variability of Mg and K concentrations in

wastewaters produced in two packinghouses.







is exempted from the requirement of the permits provided they meet all surface water quality

standards. The chemical composition of wastewater at end of the packing operation showed

elevated concentrations of all elements but the magnitude of increase was much greater for some

elements (Table 2-2). Wastewater pH was maintained in the neutral range (6.5-8) as

recommended for Florida packinghouse waste stream (Bartz et al., 2009) and these values

suggest that wastewater is suitable for irrigating most crops without any adverse effects on crop

and soil properties (Ayers and Westcot, 1989). The pH is also in the recommended range for

Florida class IV agricultural water use (Florida Administrative Weekly, 2006). However, the EC

showed marked increase in wastewater and was much greater in PKG 1 (2.8 dS m-1) than PKG 2

(1.3 dS m-') due to much greater chloride (1125 mg L1) in PKG 1 than PKG 2 (255 mg L-1).

Significant correlation of EC with chloride in our study (r = 0.95) indicated that increased

chloride in PKG 1 than PKG 2 resulted in relatively higher EC in PKG 1 wastewater than PKG

2. The high EC in the wastewater (especially of PKG 1) may pose slight to moderate restrictions

for its use as irrigation water for salt sensitive crops such as strawberry, onions, and beans (Ayers

and Westcot, 1989). The EC in our wastewater was comparable to dairy wastewater (3.1 dS m1)

but much lower than poultry lagoon wastewater (7.9 dS m'1) (Bradford et al., 2008). Chloride in

the wastewater was much elevated in PKG 1 (1125 mg L1) because of the manual control on

chlorine addition in dump tank. According to Bartz et al. (2009), when chlorine is dissolved in

water, it readily forms hypochlorous acid and hypochlorite ion (OC1-). Thus, three forms of

chlorine (Cl2, HOC1, and OC1-) are present in aqueous chlorine solution which readily oxidizes

organic compounds with different redox potentials and generate chloride ions in the solution

(Fukayama et al., 1986) as follows:










Packinghouse 1
4.0

3.5

3.0

2.5

2.0

1.5

1.0

0.5

0.0
0 50 100 150 200 250 300 350


Packinghouse 2


0 50 100 150 200 250 30(


S1200

1000

.i 800

, 600

400

200

0 5
0 50 100 150


1 onn


10o"

1600

1400

1200

1000

800

600

400

200


200 250 300 350


0 50 100 150 200 250 300


Tomatoes washed (Mg)

---- S-2 --v- S-3 -4- S-4


-0- S-1


Figure 2-2. Effect of cumulative amounts of washed tomatoes on wastewater EC and chloride
during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009.









al., 2005). Thus, field-grown tomatoes in Florida are one of the main sources of tomatoes in

Florida and the US.

Water Use and Wastewater Production in Tomato Packinghouses

There are approximately 70 tomato packinghouses in Florida that pack fresh-market

tomatoes (Agricultural Marketing Service, 2008). A typical packinghouse in Florida packs about

1.1 million kg of tomatoes in a day (http://www.sixls.com/packing.php). Packinghouses use large

amounts of fresh water to fill dump tanks used for rinsing, washing, and sanitizing field-

harvested tomatoes before packing and the amount of water required depends on the type of

tomatoes. For instance, the amount of water used for cleaning round tomatoes typically ranges

from 36,000 to 68,000 L day-1 while Roma and grape tomatoes require only 3,700 to 28,400 L

day-' (Florida Tomato Committee, 2007). Most packinghouses in Florida fill dump tanks (Figure

1-2A) with fresh water from the municipal supply before the beginning of packinghouse

operation each day and drain the wastewater from the dump tanks at end of the day. This water is

continuously recirculated in the dump tanks where field tomatoes are dumped and washed during

a typical 6 to 8 h of packing in a day (Figure 1-2B). At end of packing operation, approximately

3,800 to 18,200 L per day of wastewater is produced in the dump tanks (Florida Tomato

Committee, 2007). This equates to about 231 million L of wastewater each year in tomato

packinghouses in Florida (S. Sargent, personal communication), which needs to be disposed in

an environmentally sustainable way.

Wastewater Suitability for Environmental Use

According to a survey of Florida packinghouses, wastewater produced is mainly disposed

in three ways: 1) land application in agricultural fields (54%), 2) discharge into sewage systems

(31%), and 3) no disposal or third party disposal (15%) (Florida Tomato Committee, 2007).

Land application of wastewater in agricultural fields is a very convenient method of beneficially









observations, soil native Ca and Ca from past accumulations of applied wastewater in soil acted

as source of Ca in leachate while most of the applied P, Na, K and Mg were retained in soil.

Mass Balance of Constituents in Soil Columns

In control treatment, where no P was added, about 3 kg ha-1 of P was leached (Table 3-9).

However, in low, medium, and high treatments, about 5, 7, and 13% of applied P was leached,

respectively suggesting that low irrigation rates gives P sufficient time to react with soil

components resulting in more P fixation and less leaching potential as suggested by Mamo et al.

(2005). Since no vegetation was grown in the soil columns, remainder (87-95%) of applied P

was fixed in the soil profile.

No Na leaching was observed in the control treatment while in wastewater treatments;

about 8-61% of applied Na was leached (Table 3-9). In the control treatment, de-ionized water

leached about 65 kg ha-1 of Ca from the soil and about 100-137% of applied Ca was leached in

wastewater treatments suggesting that 10-37% of Ca in leachate was contributed by the soil

profile which includes both native soil Ca or past accumulations of applied wastewater. About 12

kg ha-1 of Mg was leached in control treatment while in wastewater treatments, about 60-82% of

applied Mg were leached in the soil. Similarly, K leached in the soil with leaching potential of

33-50% while de-ionized water leached about 29 kg of K ha-1 from the soil in the control

treatment. Overall, a part of the elements such as P, Na, Mg, and K was fixed in soil while some

of the Ca in leachate was contributed from the soil profile.

Mean Concentrations of P, Na, Ca, Mg, and K in Leachate

Wastewater application did not have any significant effect on leachate P in control and

three wastewater treatments (0.33-0.7 mg L-) (Table 3-10). In fact, control had highest mean

leachate P (0.7 mg L-) followed by high (0.6 mg L-'), medium (0.33 mg L-1), and low (0.28 mg

L-) treatments. Mean P in the applied wastewater (4 mg L-) was much greater than the leachate

58










TOMATO PACKINGHOUSE WASTEWATER: CHARACTERIZATION AND LEACHING
STUDIES





















By

MANINDER KAUR CHAHAL


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2010









determined using least significant difference (LSD) method at P <0.05 using PROC GLM

procedure in SAS statistical analysis (SAS Institute, 2007).

Results and Discussion

Physical and Chemical Properties of Soils

Soil in our study was sandy in nature (>92% sand) with very low clay content (<0.4%)

(Table 3-3). Surface horizon had lower bulk density and particle density than subsurface horizon

while porosity was similar in both horizons (28-31%). Surface soil had significantly higher pH,

EC, and organic matter than the subsurface soil (Table 3-4). Among metals, surface soil had

significantly higher total Ca, Mg, K, and P contents than the subsurface soil while Na and Fe did

not vary significantly in two horizons. In contrast, total Al was lower in surface soil (1284 mg

kg-1) than subsurface soil (1701 mg kg-1). Water extraction recovery of different elements varied

in two horizons, with greater recovery of Mg and K in surface (17-27%) than the subsurface soil

(14-17%) while Ca and Na were more water-extractable in subsurface (20-33%) than surface

(9-27%) (Table 3-5). Phosphorus was more water-extractable (8% of total P) in sub-surface than

surface soil (4% of total P) indicating that labile P may have moved from the surface layer due to

sandy nature of soil.

Chemical Characteristics of Packinghouse Wastewater Applied to Soil Columns

Mean pH of the wastewater applied to soil columns was 6.2 which was lower than other

types of wastewater such as potato processing plant wastewater (7.4) (Zvomuya et al., 2005),

dairy manure wastewater (7.0) (Harris et al., 2008), and municipal wastewater (7.2) (Woertz et

al., 2009). The EC in the wastewater ranged from 1.94 to 2.44 dS m-1 with a mean value of 2.16

dS m-1 (Table 3-6). High EC in our wastewater was due to high chloride which ranged from 551

to 638 mg L-1. Total P concentration in packinghouse wastewater ranged from 4 to 4.4 mg L-1,

which was slightly higher than the potato processing wastewater (3.6 mg L-1) (Zvomuya et al.,

49







Other elements i.e. Ca, Mg, K, Fe, and Zn showed marginal increases in wastewater than

municipal water (Table 2-1 and Table 2-4) and do not represent constraints on wastewater reuse.

Concentrations of Ca in our wastewater was similar to swine lagoon wastewater (51 mg L-1) but

much greater than municipal wastewater (4 mg L-1) (Biggs and Jiang, 2009; Szogi and Vanotti,

2009). The K concentration in wastewater was lower than the concentration reported in swine

(614 mg L-1), dairy (178 mg L-1) and poultry (1244 mg L-1) lagoon wastewater (Bradford et al.,

2008; Szogi and Vanotti, 2009). Concentration of Zn was lower than in animal manure

wastewater (0.4-0.6 mg L-1) (Bradford et al., 2008). The tremendous variability in wastewater

from different sources suggests the impact of intrinsic and extrinsic sources in elevating

concentrations of different constituents.

To comply with the surface water discharge standards for P and Cu, wastewater needs to

be treated with chemical amendments (alum, ferric chloride, lime) to remove P and Cu from the

wastewater (Ebeling et al., 2006; Kang et al., 2003; Wang et al., 2004). Another alternative could

be to use the wastewater for land irrigation. For instance, the rate of wastewater at land

application sites must not be more than 1.67 cm day-1 or 167, 000 L ha-1 day-', above which,

wastewater can cause soil toxicity to cover crops such as grasses (FDEP, 2009). A minimum

unsaturated depth of 45 cm to the water table has also been recommended to avoid ponding at

the surface and maintain aerobic conditions in the root zone area of cover crop. The primary

concern for establishing all these guidelines was to prevent the degradation of groundwater and

surface water quality from the wastewater land application.

Summary

The primary objective of this study was to characterize the quality of wastewater

produced in tomato packinghouses. To achieve our objective, wastewater samples were collected

at 30-min interval from two packinghouses in four sampling events. The obtained data suggested







Factors Affecting Concentrations of P, Cu, and Zn in Packinghouse Wastewater

A linear increase in concentrations of all chemical constituents in the wastewater with

increase in amounts of tomatoes washed (Figures 2-3 and Figure 2-4) indicated that these

constituents were carried from tomato fields as residues on fruits, leaves, or stems. The likely

source of these contaminants in wastewater may include residues of foliar applications of

insecticides, fungicides, and micronutrients (Cu, Zn) on tomato crop which on washing in

packinghouse may have elevated their concentrations in wastewater. Although the primary focus

of this study was to characterize the wastewater quality in packinghouses, a number of likely

sources have been suggested herein to explore the scope of future research to identify sources of

these constituents in wastewater.

In Florida, a variety of organophosphate insecticides with active ingredients dimethoate,

malathion, and methadiphos are foliarly applied on tomato crop to control aphids, mites, white

flies, and earthworms (Table 2-2) (Olson and Simonne, 2009). In a study by Stevens and Kilmer

(2009), tomato fruits collected from field were analyzed for residues of insecticides and about

52% of the samples showed residues of methadiphos with maximum concentration of 0.56 mg L-

. This suggests that insecticidal residues can get transferred from the tomato fruits to the water

used for washing tomatoes, and can affect the wastewater quality in packinghouses. Similarly,

foliar applied fungicides containing mono and di-K salts of phosphorus acid to manage powdery

mildew and Phytopthora species may also leave residues on the tomato fruits and foliage parts

(leaves, stems) which may act as source of P and K in the wastewater. The Cu based fungicides

(Cu hydroxide or Cu sulfate as active ingedient) are frequently used in foliar application in

tomato crops against anthracnose and early blight, and are sometimes applied 1-2 days before

harvesting. The foliar application of fungicides containing Zn salts (e.g. Mancozeb and Ziram)

against anthracnose, early blight, and grey leaf spot and fungicidies containing K such as K









decreased from 6.7 to 6.2 during 0.7-1.1 PV. During phase 3, pH was constant (6.3-6.4) in the

high treatment as there was only wastewater flow.

Application of wastewater in soil columns significantly increased the leachate EC (P

<0.05) (Table 3-8). For instance, EC in medium treatment was 13 times (1.59 dS m-1) greater

than control (0.12 dS m-'). More wastewater application in hightreatment resulted in additional

11% increase in leachate EC (1.78 dS m-) than the medium treatment. In contrast, EC was 46%

lower in low treatment (0.85 dS m-') that received half of the wastewater than medium treatment.

In control treatment, EC was <0.1 dS m-1 during 30 leaching events while in wastewater

treatments, EC ranged from 0.1 to 0.3 dS m-1 in the phase 1 (<0.7 PVs) as this was the pre-event

de-ionized water in the leachate (Figure 3-3). The application of wastewater (high EC) in soil

columns continued to displace the pre-event water (low EC) from soil profile that resulted in

increasing EC in phase 2 (0.7-1.4 PV) from 0.1 to 2.5 dS m-1. In phase 3 (>1.4 PV), leachate EC

values were similar to EC of applied wastewater (1.9-2.4 dS m-1) suggesting that equilibrium

was achieved in the soil columns.

Transport of P, Na, Ca, Mg, and K in Soil Columns

During 30 leaching events, leachate P concentration increased gradually from 0.38 to 0.96

mg L-1 in control while in wastewater treatments, P concentration increased (0.2 to 0.8 mg L-1)

only in phase 1 (0.5-0.7 PV) (Figure 3-4) as this was the pre-event water displaced by addition

of wastewater. The de-ionized water used in control treatment and in pre-wetting events

desorbed P from the soil continuously and thus soil acted as a source of P in the leachate. Since

subsurface soils had relatively high water-soluble P (12-14 mg L-1), the application of de-ionized

water having very low ionic strength resulted in increased leaching of P from the subsurface soil

while in wastewater (high ionic strength) treated soils, P was strongly adsorbed in the soil.

According to He et al. (1997), the adsorption of P increases with the increase in ionic strength at

53









P in wastewater amended treatments (<0.7 mg L1) indicating that most of the P applied with

wastewater was retained in the soil. In contrast, increase in rate of wastewater application

resulted in a linear increase in Na concentration in leachate. For instance, mean leachate Na was

0.18 mg L-1 in control while in wastewater treatments, mean Na was 35, 188, and 235 mg L-1 in

low, medium, and high treatments, respectively (Table 3-10). The highest rate of wastewater

application resulted in 25% greater Na while lowest rate of wastewater application resulted in

81% lower Na than medium treatment. The applied wastewater had higher Na concentration (358

mg L1) than the leachate Na (35-235 mg L1) suggesting that some of the Na was also retained

in the soil profile. Leachate collected in wastewater treatments had about 5-times (66-71 mg L1)

greater Ca than the control treatment (15 mg L-1). In contrast to P and Na, leachate Ca in

wastewater treatments (66-71 mg L1) was greater than the applied Ca in wastewater (47 mg L1)

suggesting that some of the Ca in leachate originated from soil profile. Concentrations of Mg and

K showed a similar behavior in wastewater treatments. Unlike Ca, Mg and K in applied

wastewater were greater than leachate from wastewater treatments suggesting that a part of the

Mg and K was retained in the soil similar to P and Na.

Implications for Land Application of Packinghouse Wastewater

We evaluated the suitability of packinghouse wastewater as irrigation water for agricultural

use following general water quality guidelines of Ayers and Westcot (1989) (Table 3-11).

According to these guidelines, pH of packinghouse wastewater was close to the suggested

normal range of 6.5-8. In contrast, EC (2.16 dS m-) and chloride (593 mg L1) in the wastewater

may pose slight to moderate restrictions on irrigation use in salt sensitive crops such as

strawberry, onions, and beans (Haman, 2009) indicating that careful management is required for

the selection of crop and irrigation practices in sites that use packinghouse wastewater as

irrigation water. The calculated SAR in the packinghouse wastewater was very high (10.8)

59









recycling the water and is widely used for various types of wastewater such as from animal

operations, industrial, and domestic sectors (Bradford et al., 2008; Duan et al., 2009; Heidarpour

et al., 2007; Scott et al., 2004). This use of wastewater can reduce the pressure on freshwater

supplies for irrigation and can provide beneficial plant nutrients, and improve soil conditions

(Debosz et al., 2002; Shiralipour et al., 1992). Moreover, this wastewater application can reduce

the need to use fresh water to keep the tomato farm roads navigable in dry weather. There is a

lack of knowledge on impact of land application of wastewater on groundwater contamination

with phosphorus (P) and trace metals (such as copper, zinc) (Bradford et al., 2008; Duan et al.,

2009). Further, urbanization and the close proximity of packinghouse to Florida's sensitive water

bodies is especially problematic as the packers need to comply with increased regulations on

using wastewater on-site or disposing of in city sewerage systems. All these factors result in

additional cost to packers. Information about the concentrations of nutrients and trace metals in

wastewater (and their likely sources) together with leaching potential of contaminants might

provide ways to safely use wastewater in the environment and reduce the operational costs of

managing wastewater in packinghouses. No information is available about the different

contaminants present in wastewater and their leaching potential when wastewater is land applied.

Research Objectives

Currently, the tomato industry in Florida is facing the dilemma of balancing economic

viability and environmental sustainability, and critical issues tied to wastewater disposal have the

potential to undermine the sustainability of the tomato industry in Florida. In Florida, land

application of tomato packinghouse wastewater is the most commonly practiced method of

wastewater disposal. However, coarse texture, low organic matter, limestone fractures, and

shallow groundwater table in most Florida soils may pose a risk to groundwater quality in terms

of contaminant leaching. To the best of our knowledge, no scientific data on the leaching









CHAPTER 1
INTRODUCTION

Tomato Production Trends in the United States

Tomatoes are one of the important vegetables consumed in the US. For instance, in 2007,

approximately 1.87 billion kg of fresh-market tomatoes were produced for domestic use in the

US (VanSickle and Hodges, 2008). The vast majority (>81%) of these fresh-market tomatoes

were grown in the south-eastern states (Alabama, Florida, Georgia, North Carolina, South

Carolina, Tennessee, and Virginia) and California. Florida is the largest producer of fresh-market

tomatoes (650 million kg or 34% of total US production) that are grown on 15,300 ha with a

total value of US $464 million. An estimated 90% of tomatoes grown in Florida are shipped out

of the state to the eastern US and Canada (VanSickle and Hodges, 2008). However, since 1991,

Florida has lost market share of tomatoes to other US producers such as California, who

increased their production by 132 million kg (Figure 1-1). In addition, imports from other

countries such as Mexico have taken an even greater share of the market from Florida producers

than production increases in other US states.

Due to variability in climatic conditions, tomatoes are grown in Florida and other south-

eastern states from fall through spring (Aug-Mar) and in California from spring through fall

(Jan-Aug) (Olson and Simonne, 2009; Strange et al., 2000). In Florida, tomatoes are

predominantly grown in Miami Dade County, Southwest Florida, the Palm Beach-Fort Pierce

region, the Tampa Bay area, and the Panhandle west of Tallahassee. These areas have two main

growing seasons in the year (Aug-Nov and Dec-May). Each year, Florida produces enough

round slicing tomatoes along with Roma, grape and cherry types for the fresh market to meet the

per capital consumption of 8 kg tomatoes per year (Florida Tomato Committee, 2003; Sargent et









Table 2-1. Selected chemical properties of municipal water used in the dump tanks in two tomato packinghouses before the cleaning
of field-harvested tomatoes
Packinghouse pH EC Chloride P Cu Zn Ca Mg K Fe
dS m1 mg L1
1 7.20.2t 0.430.1 27+3 0.270.1 0.01+0.01 0.130.03 341.5 16 0.5 60.2 0.020.01
2 7.10.1 0.38+0.1 279 0.21+0.1 0.010.01 0.11+0.01 341 150.4 60.4 0.020.01
tMeanstandard deviation

Table 2-2. Potential sources of P, Cu, Zn, and K in wastewater carried from washed tomatoes
Wastewater Application rate Days to harvest
Source Purpose -i
constituent So e P e (L ha- )
P Organo-P insecticides- Control insects like aphids, 0.5-2.9 1-7
a) Dimethoate drosophila, mites, earthworms,
b) Malathion leaf miners, whiteflies
c) Methadiphos
Fungicides Powdery mildew, Phytopthora, 1
Mono and di-K salts of phosphorus acid Pythium species
Cu Fungicides Anthracnose, early blight, late 2.0-6.7 1-2
Copper hydroxide blight
Micronutrients-foliar spray Cu deficiency in plant tissue (<5 2.3-5.7
Copper sulfate mg kg-1) on dry wt. basis
Zn Fungicides Anthracnose, early blight, late 2.7-4.5 5-7
a) Mancozeb blight, grey leaf spot
b) Ziram
Micronutrients-foliar spray Zn deficiency in plant tissue (<25 2.3-4.5
Zinc sulfate mg kg-1) on dry wt. basis
K Fungicides
a) K bicarbonate Po y
Powdery mildew
b) Mono and di-K salts of phosphorus
acid









ACKNOWLEDGMENTS

I would like to thank my committee chair, Dr. Gurpal Toor, for providing me with the

opportunity to study a truly unique system, and for his guidance and help. The expertise of my

committee members, Dr. Belinski Santos, Dr. Nkedi Peter Kizza, and Dr. George J Hochmuth

has been invaluable. I would like to thank the Environmental Protection Agency for supporting

the research. Jose Moreno, farm manager at Gulf Coast Research and Education Center, was a

tremendous help in the field. The lab staff at the Soil and Water Quality laboratory and my

fellow graduate students (Butch Bradley, Gitta Shurberg, Lu Han, Kamaljit Banger, Manmeet

Warya, Pardeepinder Brar and Sushila Chaudhari) have been great friends as well as teachers.

Last, but not least, I would like to thank my family and friends who have supported me in all my

endeavors.









cap was then packed up to 5-cm depth with a mixture of washed sand and gravels. After

packing, each end cap was securely attached to the bottom of PVC column and sealed with a

sealant to prevent water leakage, if any. A hole was drilled at the center of the end cap to which a

plastic pipe was attached to collect leachate in 2 L amber glass bottles. All the packed soil

columns were placed in the greenhouse at controlled temperature of 30-35 C (Figure 3-1) to

ensure similar experimental conditions for the duration of the experiment.

The soil columns were equilibrated by first wetting the soil with de-ionized water

equivalent to about 1 pore volume (PV) of soil (15 cm water depth or 11.1 L in each column) to

remove any air bubbles, if entrapped, during the packing of soil columns and to ensure

homogeneous moisture in all columns for subsequent experiments. Soil columns were left to

freely drain for a few days and then were wetted by adding de-ionized water equivalent to a total

of 0.8 PV (11.69 cm water depth) in 1.67 cm per day increments for 7 days. The wetting events

were continued (three events) till coefficient of variation in leachate volume was <10% in all the

columns so as to ensure uniform hydrologic flow in all columns (Table 3-1) The rationale for

using 1.67 cm per day as application was that it corresponded to about 0.2 PV of soil columns

and hence prevented any ponding on the soil columns.

Treatments and Leachate Collection

In the greenhouse, 12 packed soil columns were arranged, in triplicates, for control and

three application rates (Low, Medium, and High) of wastewater treatments (Table 3-2). Control

treatment received de-ionized water while the medium treatment received packinghouse

wastewater, both at the rate of 1.67 cm per day. Other two treatments received wastewater

application at low (0.87 cm per day) and high rates (2.5 cm per day). This was done to determine

the likely impacts of adding wastewater below and above the medium application rate (1.67 cm

per day). All soil columns were continuously irrigated for about 10 min once a day using the

46









Column Preparation, Setup, and Equilibration...................... ...................... 45
Treatm ents and Leachate Collection ........................................ .......................... 46
Soil and W after Analysis .................................. .. ... ........ ............ 47
Statistical A analysis ........................ .. .......................... .. .... ........ ........ 48
R results and D iscu ssion .................................................................................................... 49
Physical and Chemical Properties of Soils................................................. ................. 49
Chemical Characteristics of Packinghouse Wastewater Applied to Soil Columns.........49
Leachate Volum e in Soil Columns............................................................ ......50
Chloride Breakthrough in Wastewater Amended Soil Columns.................................51
Leachate pH and EC in Control and Wastewater Amended Soil Columns ..................52
Transport of P, Na, Ca, M g, and K in Soil Columns...................................................53
M ass Balance of Constituents in Soil Columns ....................................... ...... ..... 58
Mean Concentrations of P, Na, Ca, Mg, and K in Leachate ............... ............ .....58
Implications for Land Application of Packinghouse Wastewater...............................59
S u m m a ry ................... ............................................................ ................ 6 1

4 LEACHING OF TRACE METALS IN A SANDY SOIL IRRIGATED WITH
WASTEWATER ............................... ...... ... .... ............ 71

Intro du action ................... ......................................................... ................ 7 1
M materials and M ethods ..................................... .. .. .. ........ .. ............73
Study Site and Sam ple C collection ........................................................ .....................73
Column Preparation, Setup, and Equilibration...................... ...................... 73
Treatm ents and Leachate Collection ........................................ .......................... 75
Soil and W after Analysis .................................. .. ... ........ ............ 76
Statistical A analysis ........................ .. .......................... .. .... ........ ........ 77
R results and D iscu ssion .................................................................................................... 77
Physical and Chem ical Properties of Soils....................................... .........................77
Concentrations of Trace Metals in Packinghouse Wastewater Applied to Soil
C o lu m n s ......................................................... ................ ................ 7 8
Leachate Volume in Soil Columns.......................................................... ... .....78
Chloride Breakthrough in Wastewater Amended Soil Columns.................................... 79
Trace Metals Transport in Soil Columns Amended with Packinghouse Wastewater.....80
Mass Balances of Trace Metals in Wastewater Amended Soil Columns .....................82
S u m m a ry ................... ............................ ............................. ................ 8 4

5 SUMMARY, CONCLUSIONS, AND RECOMMENDATION ......................................91

L IST O F R E F E R E N C E S .................................................................................... .....................94

BIOGRAPHICAL SKETCH ............................................................. ...........103









watering can. The wastewater used in the study was collected from one of the packinghouse. The

collected wastewater (400 L at end of the packing operation) was filtered through a cheesecloth

to remove leaves and debris and was stored at 40C till use in the leaching experiment.

A total of 30 leaching events were conducted based on daily application of wastewater in

the soil columns during August- September 2009. The rationale for conducting daily leaching

events for 30 days was to be consistent with the field practice as packinghouse wastewater

supply and use is seasonal (typically 4-6 weeks two times a year). The application of wastewater

for 30 days resulted in addition of about 5 PV of irrigation water in high wastewater treatment.

While the control and medium wastewater treatments received 3.3 PV and low wastewater

treatment received 1.6 PV during 30 day period. Leachate was collected after 24-h of

equilibration, leachate volume was measured, and a sub-sample was taken for analysis.

Soil and Water Analysis

Soil samples from both horizons were analyzed for sand, silt, and clay using hydrometer

method (Day, 1965). Field bulk density of undisturbed soil cores was determined as described in

Blake and Hartge (1986) by collecting samples at 5-cm depth intervals beginning from 0 to 50

cm. Particle density of soil horizons was measured using Pycnometer method of Blake and

Hartge (1986). Using the bulk density and particle density of soil samples, porosity of each soil

horizon was calculated according to following equation.



SParticle density
Porosity (%)= BuParticleBUlk density xl100d


Soil pH was measured by equilibrating 10-g of soil with 20-mL of de-ionized water (1:2)

for 1-h with a digital meter (Accumet XL60, Dual channel pH/ion/conductivity/dissolved

oxygen meter, Fisher Scientific, Pandan Crescent, Singapore). The electrical conductivity (EC)

of soil samples was measured using a soil to de-ionized water suspension (1:1) with the same

47











Packinghouse 1


2




0 50 100 150 200 250 300 350 0
1 1 3 5


6



4



2



0


3.5

3.0

2.5

' 2.0

1.5

1.0

0.5

0.0


035

030

025

'- 0 20

'0 15

0 10

0 05

0 00


10


08


-06


04


02


00


----0 00 --
0 50 100 150 200 250 300 350 0
S 10


50 100 150 200 250 300


50 100 150 200 250 300


50 100 150 200 250 300


02


00


0 50 100 150 200 250 300 350 0 50 100 150 200 250 300
Tomatoes washed (\ 1

-- S-1 -0- S-2 -v- S-3 -- S-4


Figure 2-3. Effect of cumulative amounts of washed tomatoes on wastewater P, Cu, Zn, and Fe

during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009.


-- 00 o
0 50 100 150 200 250 300 350 0

0 35


Packinghouse 2









2005) while much lower than domestic wastewater (>10 mg L-1) (Vaillant et al., 2004) and dairy

wastewater (28 mg L-) (Harris et al., 2008).

Among cations, wastewater was rich in Na (349-377 mg L-1) followed by Ca (45-50 mg

L-1), K (32-34 mg L-1), and Mg (21-23 mg L-1). In dairy wastewater, Harris et al. (2008)

observed higher concentrations of Ca, Mg, and K (138, 64, and 248 mg L-1, respectively) but

lower Na (75 mg L-1) than our packinghouse wastewater. Similarly, in paper-mill wastewater,

higher values of Na (422 mg L-1) and Ca (108 mg L-1) than our wastewater were observed by

Howe and Wagner (1996).

Leachate Volume in Soil Columns

After 30 leaching events, significant differences in mean leachate depth (cm day-1) were

observed in all treatments (Table 3-7). For instance, wastewater input was greatest in high (2.51

cm day-1) resulting in a greater drainage depth of 2.31 cm day-' (92% of applied water) followed

by medium and control (1.45-1.51 cm day-1 or 88-91%), and low (0.66 cm day-1 or 79%)

treatments. Wastewater treatments exhibited variability in daily leachate volume with more

volume recovered in high followed by medium and low treatments due to variable amount of

water application.

Leachate to irrigation (LI) ratios in all treatments was <1 during 30 leaching events

indicating that a part of the applied water was always stored in the soil columns (Figure 3-2A).

The first eight leaching events showed a continuous and gradual increase in LI ratios from 0.70

to >0.85 in all treatments. Kleinman et al. (2005) observed that initial leaching events play a

significant role in the emergence and development of water flow paths in the soil and continuous

irrigation events can lead to apparent steady state flow in soil columns. In subsequent leaching

events, LI ratio was 0.86-0.96 in all but low treatment. The LI ratio increased simultaneously at

the end of the experiment and was 0.94 in high, 0.88-0.9 in medium and control, and 0.75 in low

50










Table 2-3. Simple and stepwise regression models for predicting concentrations of P, Cu, and Zn in wastewater (mg L-) with the
amount of tomatoes washed (t), wastewater pH, and chloride (Cl) in two tomato packinghouses
Wastewater Packinghouse 1 Packinghouse 2
constituent
Step R2 P value R2 P value
P 1 0.75 + 0.015 t 0.53 <0.05 0.37 + 0.009 t 0.92 <0.05
2 -8 + 0.23 pH + 0.016 t 0.54 NS 3.33 0.42 pH + 0.01 t 0.94 <0.05
3 -0.49 + 0.004 C1 + 0.01 t 0.76 <0.05 0.24 + 0.002 Cl + 0.007 t 0.92 NS
4 -5.03 + 0.66 pH + 0.004 C1 + 0.0075 t 0.78 <0.05 3.44 0.5 pH + 0.002 Cl + 0.007 t 0.94 <0.05

Cu 1 -0.0008 + 0.0074 t 0.72 <0.05 0.11 + 0.008 t 0.76 <0.05
2 -1.28 + 0.18 pH + 0.007t 0.73 NS -5.2 + 0.76 pH + 0.007 t 0.82 <0.05
3 -0.22 + 0.00006 Cl + 0.006t 0.76 <0.05 -0.11 + 0.003 Cl + 0.005 t 0.77 NS
4 -2.06 + 0.27 pH + 0.0007 Cl 0.78 <0.05 -5.0 + 0.71 pH + 0.002 Cl + 0.006 t 0.83 NS

Zn 1 0.12 + 0.00054 t 0.75 <0.05 0.09 + 0.0002 t 0.33 <0.05
2 -0.08 + 0.029 pH + 0.0006 t 0.79 <0.05 0.16 0.01 pH + 0.0002 t 0.34 NS
3 0.12 + 0.00002 C1 + 0.0006 t 0.75 NS 0.1 + 0.0001 Cl + 0.0003 t 0.35 NS
4 -0.071 + 0.03 pH- 0.00001 C1 + 0.000 6 t 0.79 NS 0.15 0.01 pH 0.0001 Cl + 0.0003 0.36 NS
t
NS: Non significant

Table 2-4. Selected chemical properties of wastewater produced in the dump tanks in two tomato packinghouses at the end of packing
operations
Packinghouse pH EC Chloride P Cu Zn Ca Mg K Fe
dS m-1 mg L-1
1 6.60.7t 2.80.6 1125419 5.71.7 2.20.7 0.30.1 596 252 4914 0.80.2
2 7.1+0.4 1.3+0.2 255+86 2.8+0.3 1.9+0.8 0.1+0.1 55+4 21+1 24+2 0.1+0.1
tMean standard deviation







that EC and chloride were elevated in the wastewater because of the use of chlorine based

sanitizers in the dump tanks and may pose moderate to strict restrictions for their use as irrigation

water in crops like beans, carrot, okra, onion, and strawberry (Haman, 2009). The concentrations

of wastewater constituents were relatively higher in PKG 1 than PKG 2, which were mainly due

to the relatively more contact time of tomatoes with dump tank water in PKG 1. Among all

elements, P was above the threshold limit of 0.74 mg L-1 for surface water discharge in Tampa

Bay watersheds and Cu concentration was above the threshold limit of 0.03 mg L-1 for

groundwater discharge and 0.5 mg L-1 for irrigation water in agriculture (Florida Administrative

Weekly, 2006). Concentrations of Fe and Zn were less than the threshold value (1 mg L-) of

irrigation water suitability in agriculture (Ayers and Westcot, 1989). In our study, washing of

tomatoes resulted in increased concentrations of all chemical constituents in the wastewater. This

suggests that tomato residues (residues of pesticides, insecticides, and/or foliar-applied

micronutrients) carried with field harvested tomatoes may be the likely sources ofP and Cu in

wastewater. These results suggest that wastewater needs to be treated for P and Cu if directly

discharged to surface water bodies as their concentrations were above the critical values.









and <5 mg L-1, respectively (Magesan et al., 1999). They attributed the leaching behavior of

cations to the preferential flow in soil and removal of cations in soil that were applied with past

irrigations. These studies have shown that the wastewater characteristics such as concentration of

P, Ca, and Al (Mamo et al., 2005; Woodard et al., 2007) as well as soil characteristics such as

texture, contents of P, and soil minerals such as Fe and Al oxides in soil (Toth et al., 2006;

Zvomuya et al., 2005) along with uptake of P by plants (Barton et al., 2005) control the

movement ofP in the soil profile.

Lastly, the climatic factors can play an important role in determining the extent of P

leaching in a soil. For example, Florida receives about 135 cm rainfall each year, which may

enhance the leaching of P in the sandy soils. Thus, wastewater, soil, and rainfall conditions in

Florida highlight the concern of P leaching in soils amended with tomato packinghouse

wastewater as 54% of the packinghouse wastewater is disposed in agricultural lands (Florida

Tomato Committee, 2007). To the best of our knowledge, no information is available about the

effect of packinghouse wastewater on the transport and/or retention of P and cations such as Ca,

Mg, and Na when applied in coarse textured soils. Thus, our objective in this study was to

evaluate potential leaching of P and cations in a typical Florida sandy soil amended with

packinghouse wastewater. The information thus obtained, can be used to assess the feasibility

and fine-tune the land application of wastewater to reduce leaching losses of P and prevent

groundwater contamination in Florida.

Materials and Methods

Study Site and Sample Collection

Soil used in column study was obtained from the Gulf Coast Research and Education

Center, University of Florida in Wimauma, FL (Latitude: 270 45' 44.13" N; Longitude: 820 13'

20.36" W). The soil at the site is somewhat poorly drained (seasonal water table 60 to 106 cm)

44









were continued (three events) till coefficient of variation in leachate volume was <10% in all the

columns so as to ensure uniform hydrologic flow in all columns (Table 4-1) The rationale for

using 1.67 cm per day as application was that it corresponded to about 0.2 PV of soil columns

and hence prevented any ponding on the soil columns.

Treatments and Leachate Collection

In the greenhouse, 12 packed soil columns were arranged, in triplicates, for control and

three application rates (Low, Medium, and High) of wastewater treatments (Table 4-2). Control

treatment received de-ionized water while the medium treatment received packinghouse

wastewater, both at the rate of 1.67 cm per day. Other two treatments received wastewater

application at low (0.87 cm per day) and high rates (2.5 cm per day). This was done to determine

the likely impacts of adding wastewater below and above the medium application rate (1.67 cm

per day). All soil columns were continuously irrigated for about 10 minutes once a day using the

watering can. The wastewater used in the study was collected from one of the packinghouse. The

collected wastewater (400 L at end of the packing operation) was filtered through cheesecloth to

remove leaves and debris and was stored at 40C till use in the leaching experiment.

A total of 30 leaching events were conducted based on daily application of wastewater in

the soil columns during August- September 2009. The rationale for conducting daily leaching

events for 30 days was to be consistent with the field practice as packinghouse wastewater

supply and use is seasonal (typically 4-6 weeks two times a year). The application of wastewater

for 30 days resulted in addition of about 5 PV of irrigation water in high wastewater treatment.

While the control and medium wastewater treatments received 3.3 PV and low wastewater

treatment received 1.6 PV during 30 day period. Leachate was collected after 24-h of

equilibration, leachate volume was measured, and a sub-sample was retained for analysis.




























IP


Figure 4-1. Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse: A)
cheesecloth fixed at the bottom of an end cap, B) end caps filled with sand and
gravels, C) and D) packed soil columns.









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215.


102











1000

-900 --- California
-- Florida
8- Rest of US
800 -


a 700


S600


500


H 400


300
1992 1994 1996 1998 2000 2002 2004 2006 2008
Year
Figure 1-1. Yearly fresh-market tomato production in US (VanSickle and Hodges, 2008).









application rate than medium rate suggested that soil was not completely saturated in low

application rate. Camobreco et al. (1996) reported similar results with chloride breakthrough in

the homogenized soil columns where breakthrough was observed after 0.5-0.7 PV of leachate

and the ratio continued to increase till it reached unity (1) indicating soil matrix flow in their soil

profile. In phase 3 (after 1.1 PV), there was only wastewater flow in the leachate. The C/Co ratio

did not show any significant increase and ranged from 0.7 to 1 indicating the steady state flow of

wastewater. In general, breakthrough curves obtained in our study were typical of the

homogeneous soil media indicating the flow from soil matrix only (Camobreco et al., 1996).

During the study period, leachate chloride showed maximum concentration of 619-626 mg L-1 in

three application rates. These concentrations were greater than the groundwater cleanup target

level of 250 mg L-1 (Florida Administrative Code, 2010; Florida Administrative Weekly, 2006)

suggesting that wastewater application can increase concentration of chloride in the groundwater.

Leachate pH and EC in Control and Wastewater Amended Soil Columns

Mean pH of 30 leaching events was greater in control and low (6.87-6.91) than medium

and high treatments (6.44-6.53) (Table 3-8). Leachate pH was significantly greater (P<0.05) in

control (6.9) and medium (6.5) treatments suggesting that wastewater application at medium rate

(1.67 cm day-') decreased the leachate pH which can be attributed to the acidic nature of

wastewater. Increasing the wastewater application rate above medium to high did not

significantly decrease the pH (6.4). During 30 leaching events, leachate pH was about neutral

(6.7-7.0) in the control treatment while in wastewater treatments, leachate pH ranged from 6.6 to

7.1 in phase 1 (<0.7 PV) which was the pH of pre-event water (Figure 3-3). In phase 2 of mixture

of wastewater and pre-event water, leachate pH declined gradually and approached close to the

wastewater pH of 6.2 in high treatment. For instance, in medium and high treatments, pH









LIST OF TABLES


Table Page

2-1 Selected chemical properties of municipal water used in the dump tanks in two
tomato packinghouses before the cleaning of field-harvested tomatoes .........................35

2-2 Potential sources of P, Cu, Zn, and K in wastewater carried from washed tomatoes........35

2-3 Simple and stepwise regression models for predicting concentrations of P, Cu, and
Zn in wastewater (mg L-) with the amount of tomatoes washed (t), wastewater pH,
and chloride (Cl) in two tom ato packinghouses ..................................... .................36

2-4 Selected chemical properties of wastewater produced in the dump tanks in two
tomato packinghouses at the end of packing operations ................................................36

3-1 Pre-wetting/pre-event irrigation schedule in soil columns using de-ionized water
during July-A ugust 2009............................................................................. 62

3-2 Treatm ents applied in soil columns ............................................................................62

3-3 Selected physical properties of surface (0-17 cm) and subsurface (17-50 cm) soils in
the packed soil column ns .................. ..................................... .. ...... .... 62

3-4 Selected chemical properties of surface (0-17 cm) and subsurface (17-50 cm) soils
in the packed soil column ns ......................................................... ... .................. 63

3-5 Water-extractable (soil to water ratio= 1:10) elements (mg kg-1) in two soil horizons
packed in the soil column ns ......................................................... ... .................. 63

3-6 Selected chemical properties of packinghouse wastewater applied in the soil columns ...64

3-7 Mean leachate volume of 30 leaching events in control and wastewater irrigated soil
c o lu m n s ................... .......................................................... ................ 6 4

3-8 Mean pH and EC values in leachate collected from four treatments in 30 leaching
ev e n ts ......................................................... ..................................6 4

3-9 Total amounts of P and cations (Na, Ca, Mg, and K) applied in the soil columns,
amounts, and percent leaching of applied amounts in four treatments in 30 leaching
ev e n ts ......................................................... ..................................6 5

3-10 Mean leachate concentrations (mg L-) of P and cations in four treatments after 30
leachin g ev ents ...................................... .................................................. 6 5

3-11 Guidelines for interpretation of water quality for irrigation purposes in agriculture
(A years and W estcot, 1989) ........................................................................ .................. 66









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Stevens, T.J., and Kilmer, R.L. 2009. A descriptive and comparative analysis of pesticide
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Strange, M.L., W.L. Schrader, and T.K. Hartz. 2000. Fresh-market tomato production in
California. Vegetable research and information center: vegetable production series,
University of California/Division of agriculture and natural resources.

Szogi, A.A., and M.B. Vanotti. 2009. Removal of phosphorus from livestock effluents. J.
Environ. Qual. 38:576-586.

Tam, N.F.Y., and Y.S. Wong. 1996. Retention and distribution of heavy metals in mangrove
soils receiving wastewater. Environ. Pollut. 94:283-291.

Tijani, M.N. 2009. Contamination of shallow groundwater system and soil-plant transfer of trace
metals under amended irrigated fields. Agr. Water Manage. 96:437-444.

Toor, G.S., B.J. Cade-Menun, and J.T. Sims. 2005a. Establishing a linkage between phosphorus
forms in dairy diets, feces, and manures. J. Environ. Qual. 34:1380-1391.


100









PKG 2 Packinghouse 2

PV Pore volume

PVC Polyvinyl chloride

SAR Sodium adsorption ratio

Se Selenium

Zn Zinc









treatments. Due to the application of variable rates of irrigation water, high treatment leached a

total of 4.3 PV of water followed by control and medium (2.9-3 PV), and low (1.4 PV) (Figure

4-2B).

Chloride Breakthrough in Wastewater Amended Soil Columns

Chloride anion is a non-reactive tracer and thus, indicates the flow of water in the soil via

chloride breakthrough curves. In our study, the curves had sigmoid shape (S shape) in all

treatments (Figure 4-2C), indicating that chloride and water flows were similar throughout the

system in spite of the different application rates of wastewater. The relative chloride

concentration ratio (C/Co) of 0.5 in the curve corresponds to about 1 PV of leachate in three

treatments indicating that there was no preferential flow in the soil. This can be due to the

homogeneous packing of soil columns with sandy soil that is typical of Florida.

The graph is divided in three phases based on the nature of leachate. For instance, in phase

1, the leachate during first 0.7 PV in all soil columns was the pre-event water (de-ionized water)

after being displaced by applied wastewater. Thus, leachate had very low C/Co chloride ratio. In

phase 2 (0.7-1.4 PV), there was a flow of wastewater along with pre-event water in the leachate

and showed convective solute transport in the system. As a result, C/Co ratio gradually increased

in all treatments. The breakthrough (increase in C/Co ratio) was observed first in high

application rate followed by low and medium application rate. The early breakthrough in low

application rate than medium rate suggested that soil was not completely saturated in low

application rate. Camebreco et al. (1996) reported similar results with chloride breakthrough in

the homogenized soil columns where breakthrough was observed after 0.5-0.7 PV of leachate

and the ratio continued to increase till it reached unity (1) indicating soil matrix flow in their soil

profile. In phase 3 (after 1.1 PV), there was only wastewater flow in the leachate. The C/Co ratio

did not show any significant increase and ranged from 0.7 to 1 indicating the steady state flow of









diameter) irrigated with wastewater at three different application rates for 30 days (0.84, 1.67,

2.51 cm day-1) showed that soil acted as a sink for phosphorus, copper, manganese, sodium, and

potassium whereas calcium, magnesium, iron, and zinc applied with wastewater were not

retained and were vertically transported to a depth of 50 cm. The high ionic strength (0.031

moles L-) and high sodium adsorption ratio (10.8) of wastewater resulted in phosphorus and

sodium adsorption in the soil. The application of wastewater at medium rate (1.67 cm day-1) did

not affect leaching behavior of phosphorus, copper, and iron whereas calcium, magnesium,

potassium, manganese, and zinc losses were increased by 2-7 times as compared to the control.

Application of wastewater at the high rate (2.51 cm day-') increased the leaching losses of

phosphorus and all metals by 1.3-3 times. This result suggested that the long term application of

wastewater at high rate can increase the leaching of phosphorus and trace metals and can

potentially cause groundwater contamination. However, our results showed that packinghouse

wastewater can be safely applied at sandy soils at 1.67 cm day-1 without significant concern of

increased phosphorus and copper leaching.









Table 4-7. Mean leachate concentrations (mg L-1) of trace metals in four treatments in 30
leaching events
Treatment Cu Zn Fe Mn
Control 0.190. 1at 0.130. a 0.850.2a 0.120.la
Low 0.20.la 0.310.09b 1.680.6b 0.480.2b
Medium 0.190.02a 0.320.06b 1.170.lab 0.280.lab
High 0.190. la 0.30.01b 0.80.2a 0.150.la
LSDt 0.06 0.11 0.64 0.21


tMeanstandard deviation
Values followed by same letter in a column are not significantly different at P<0.05
Least significant difference


Table 4-8. Total amounts of trace metals (Cu, Fe, Mn, and Zn) applied in the soil columns,
amounts leached, and percent leaching of applied amounts in four treatments in 30
leaching events
Treatment Cu Zn Fe Mn
Amounts applied (kg ha-1)
Control 0 0 0 0
Low 1.6 0.39 1.1 0.86
Medium 3.3 0.8 2.2 1.7
High 5.0 1.17 3.3 2.6
Amounts leached (kg ha-')
Control 0.830.lbt 0.570.2a 3.6+1ab 0.510.4a
Low 0.40.la 0.620.2a 3.31+1.la 0.940.4ab
Medium 0.860.lb 1.480.3b 5.240.6ab 1.270.2b
High 1.330.3c 2.120.lc 5.451.3b 1.040.lab
LSDt 0.32 0.34 1.97 0.53
Percent leached
Low 25 159 300 109
Medium 26 185 238 74
High 27 181 163 40
tMeanstandard deviation
Values with same letter in a column are not significantly different at P<0.05
jLeast significant difference at P<0.05









treatments. Due to the application of variable rates of irrigation water, high treatment leached a

total of 4.3 PV of water followed by control and medium (2.9-3 PV), and low (1.4 PV) (Figure

3-2B).

Chloride Breakthrough in Wastewater Amended Soil Columns

Chloride anion is a non-reactive tracer and thus, indicates the flow of water in the soil via

chloride breakthrough curves. In our study, the curves had sigmoid (S) shape in all treatments

(Figure 3-2C), indicating that chloride and water flows were similar throughout the system in

spite of the different application rates of wastewater. The relative chloride concentration ratio

(C/Co) of 0.5 in the curve corresponds to about 1 PV of leachate in three treatments indicating

that there was no preferential flow in the soil. This can be due to the homogeneous packing of

soil columns with sandy soil that is typical of Florida. For the chloride breakthrough, at about 1

PV, 50% (i.e. C/Co = 0.5) of the applied chloride appeared in the leachate (Figure 3-2C ), which

was an indicator of the uniform convective transport or lack of preferential transport in our study

(Mamo et al., 2005). According to Mamo et al. (2005), if preferential flow had occurred, chloride

would have appeared earlier and also at a high concentration or close to the wastewater

concentration. However, this was not the case in our study where solute transport occurred

through soil matrix only.

The graph is divided in three phases based on the nature of leachate. For instance, in phase

1, the leachate during first 0.7 PV in all soil columns was the pre-event water (de-ionized water)

after being displaced by applied wastewater. Thus, leachate had very low C/Co chloride ratio. In

phase 2 (0.7-1.4 PV), there was a flow of wastewater along with pre-event water in the leachate

and showed convective solute transport in the system. As a result, C/Co ratio gradually increased

in all treatments. The breakthrough (increase in C/Co ratio) was observed first in high

application rate followed by low and medium application rate. The early breakthrough in low

51









wastewater. In general, breakthrough curves obtained in our study were typical of the

homogeneous soil media indicating the flow from soil matrix only (Camobreco et al., 1996).

During the study period, leachate chloride showed maximum concentration of 619-626 mg L-1 in

three application rates. However, these concentrations were greater than the groundwater cleanup

target level of 250 mg L-1 (Florida Administrative Code, 2010; Florida Administrative Weekly,

2006) suggesting that amounts of wastewater needs to be carefully applied to avoid the

accumulation of chloride in the groundwater.

Trace Metals Transport in Soil Columns Amended with Packinghouse Wastewater

During 30 leaching events, daily leachate Cu concentration varied between 0.15 and 0.22

mg L-1 in the control treatment (Figure 4-3). In wastewater treatments, Cu increased from 0.11 to

0.25 mg L-1 during first 0.5-0.7 PV of leaching (phase 1) which was the pre-event water stored

in the soil profile from previous de-ionized water applications. This was followed by a decrease

in concentration till 0.9-1.3 PV (phase 2). In phase 3 (>0.9-1.3 PV), leachate Cu began to

increase gradually and approached phase 1 concentrations (-0.25 mg L-1) in medium and high

treatments. Overall, concentrations of Cu in leachate collected from wastewater amended soil

columns were much below (<0.32 mg L-1) than the applied wastewater Cu concentration (0.5-

0.73 mg L-1) suggesting that most of the Cu was retained in the soil. Elliott et al. (1986) reported

that Cu was strongly adsorbed in the soil after sludge application that resulted in low leaching

losses.

Concentration of leachate Zn was 0.1-0.2 mg L-1 in the control while in wastewater

treatments, Zn concentration was initially 0.1-0.3 mg L-1 till 0.7 PV (pre-event water) or phase 1

but then gradually increased and exceeded the applied wastewater concentration of 0.16 mg L-1

(Figure 4-3). It seems that additional Zn in leachate was due to desorption of Zn from soil in the

wastewater treatments. According to Barton and Karathanasis (2003), desorption of Zn in the









in our study are expected to have sufficient amounts of these minerals. In addition, application of

gypsum (CaSO4) is a common practice in Florida to buffer the soil pH in acidic soils suggesting

that dissolution of these minerals with de-ionized water can also release some of these elements.

During phase 2 (0.6-1.4 PV), leachate concentrations of these cations increased. In case of Ca

and Mg, leachate concentration exceeded the wastewater concentration at 0.8-0.9 PV and

reached to the maximum concentration of 150-180 mg L1 and 40-49 mg L-1, respectively at

1.1-1.3 PV (13-15 L) indicating that some of the Ca and Mg in leachate might have originated

either from the soil or past accumulations of applied wastewater. However, in case of K, leachate

concentration reached the maximum concentration of 24-27 mg L-1 at 1.1 PV (12-13 L) but was

less than wastewater concentration suggesting that some of the applied K was always fixed in

soil. Since K is mainly exchangeable in two forms: soil solution K, and exchangeable or

available K which is present on the surface of minerals, the desorption of K in our soil was most

likely from the K bounded to soil minerals. Because soil profile might have also contained some

pre-event water, some K was available in solution forms. In phase 3 (>1.4 PV), leachate

concentrations of cations decreased and became constant in case of Ca and Mg while for K,

leachate concentration began to increase after 2.9 PV. Interestingly, Ca concentration was always

above the wastewater concentration while Mg showed the concentration below wastewater

applied Mg after 1.7-1.8 PV indicating the re-accumulation of Mg in soil. According to

Miyamoto and Pingitore (1992), continuous addition of Mg in soil may sometimes exceed the

solubility product of Mg compounds which results in re-adsorption of Mg in the soil similar to

our observation. In addition, high Ca:Mg ratio in our soil (7:1) and applied wastewater (2:1) may

also result in less retarded flow of Ca as compared to Mg in the soil. Thus, based on our


































This work is dedicated to my parents, brother, and sister. It would not have been possible without
their love, support and encouragement.









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swine, In A. J. Lewis and L. Lee Southern, eds. Swine Nutrition, 2nd ed. CRC press LLC,
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and household compost on soil physical, chemical and microbiological properties. Appl.
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Duan, R., C. Sheppard, and C. Fedler. 2009. Short-term effects of wastewater land application on
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phosphorus from microscreen backwash effluent. Aquacult. Eng. 35:61-77.







Results and Discussion

Amount of Tomatoes Packed in the Packinghouses

Over four sampling events, an average of 305 Mg of tomatoes were packed in 8-h in PKG

1 while 287 Mg of tomatoes were packed in 6-h in PKG 2 (Figure 2-1). Most of the tomatoes

packed in PKG 1 during first 6 h of operation were Roma tomatoes (average weight: 102-121 g)

while round tomatoes (average weight: 170-252 g) were packed during the last 1-2 h of packing

operation in a day (North Carolina Agricultural Research Service, 2002; Scott et al., 2009). In

contrast, in PKG 2, only round tomatoes were packed. As a result of different type of tomatoes,

the rate of dumping in the dump tanks varied from 55-72 second per 454 kg of small sized Roma

tomatoes (PKG 1) to 29-40 second per 454 kg of large sized round tomatoes (PKG 2). This

variability in types of tomatoes resulted in greater contact time of tomatoes with dump tank

water in PKG 1 than PKG 2 and lower rate of tomato packing in the former (38 Mg per h) than

the latter (48 Mg per h) packinghouse.

Chemical Characteristics of Municipal Water Used in Packinghouses

As municipal water was used in the dump tanks of both packinghouses to wash and

sanitize the field-harvested tomatoes, the pH (7.1-7.2) and EC (0.38- 0.43 dS m-1) of water was

similar. The concentrations of all chemical constituents such as chloride, P, Ca, Mg, K, Cu, Fe,

and Zn in the municipal water were similar in two packinghouses (Table 2-1) as both

packinghouses were located in a close proximity with each other and had the same source of

municipal water.

Effects of Amounts of Tomatoes Packed on Wastewater EC and Chloride

Concentrations of EC and chloride in wastewater continuously increased as more tomatoes

were washed (Figure 2-2). However, the magnitude of increase was much greater in PKG 1 than

PKG 2. For instance, in PKG 1, EC increased from 0.4 to 1.2-2 dS m-1 and chloride increased

from 24 to 375-700 mg L-1 after washing 50 Mg of tomatoes. In contrast, EC and chloride were

25









digital meter. Total soil organic matter was determined by the oxidation method of Walkley and

Black (1934). Total P and 6 cations including Al, Ca, Fe, potassium (K), Mg, and Na were

extracted from soils, in triplicates, using HNO3 and H202 (USEPA method 3050, 1996) followed

by analysis on inductively coupled plasma-optical emission spectroscopy (ICP-OES)

(PerkinElmer Optima 2100 DV; PerkinElmer, Shelton, CT). Water extractable P and detectable 6

cations (Al, Ca, Fe, K, Mg, and Na) were measured by extracting 4-g of air-dried soil with 40-

mL of de-ionized water (1:10 soil to water ratio) in a reciprocating shaker for 2-h followed by

centrifugation at 4000 rpm for 20-min. The solution was then filtered through 0.45-[m

membrane filter paper and filtrate was analyzed for P and 6 cations by ICP-OES.

Wastewater and leachate pH and EC were measured by using above digital meter. Chloride

in wastewater and leachate was determined using a discrete analyzer (AQ2+, Seal Analytical Inc,

Mequon, WI). Phosphorus and cations (Al, Ca, K, Mg, and Na) in all wastewater and leachate

were analyzed using above ICP-OES. The ionic strength of wastewater was calculated using the

Marion and Babcock (1976) ionic strength equation.

Log Ie = -1.841+(1.009 x Log EC)

Where:

Ie = Ionic strength (moles L1)

EC = Electrical conductivity (dS m-1)

Statistical Analysis

Basic statistics including mean, standard deviation, range, and coefficient of variation of

parameters in leachate samples were performed in Microsoft Excel 2007. Mean concentration

(mg LU) of each element was multiplied with leachate volume to calculate loads. Significant

differences in concentrations and loads among control and three wastewater treatments were









oxides present in sandy soils was dissolved within 3-day following irrigation. We observed

increased concentrations of Mn in leachate suggesting these findings.

Mean concentrations of Cu in leachate were similar in control and three wastewater

treatments (0.19-0.20 mg L-1) while Zn was 2-times greater in wastewater (0.30-0.32 mg L-1)

than control (0.13 mg L-) (Table 4-7). No effect of increasing wastewater application rate from

low to high was observed for Cu and Zn. However, mean concentrations of Fe and Mn decreased

as application rate of wastewater increased from low to high. The flow of pre-event water from

the soil columns to leachate resulted in removal of only one trace metal (Cu) while Fe and Mn

leaching was decreased till all pre-event was displaced by wastewater. This can be because of the

relatively higher fraction of water soluble Cu (2-7.5% of total) in the soil than Fe and Mn

(0.23-3%). During 30 leaching events, the maximum concentrations of Cu and Zn in leachate

were 0.30 and 0.86 mg L-1, respectively which were below the drinking water limits of 1.3 mg L-

1 for Cu and 5 mg L-1 for Zn (USEPA, 2010). Thus, there is least possibility for these metals to

be leached in groundwater and affect its quality.

Mass Balances of Trace Metals in Wastewater Amended Soil Columns

Application of de-ionized water removed 0.83 kg Cu ha-1 from the soil in 30 leaching

events in the control treatment (Table 4-8). However, wastewater application in low treatment

actually resulted in decreasing leaching loss of Cu (0.4 kg ha-1). It may be because the low

irrigation amount allowed more interaction of Cu applied in wastewater with soil organic matter

and mineral oxides. In the medium treatment, about 0.86 kg ha-1 of Cu was leached which was

similar to control treatment (0.83 kg ha-'). The percentage leaching losses of Cu were 25-27% of

applied Cu in wastewater treatments suggesting that the remainder of 73-75% of applied Cu was

retained in the soil columns. Lin et al. (2008) reported that in a coarse textured soil, most of the

Cu applied with wastewater was adsorbed to Fe oxides, soil organic matter and Mn oxides









Florida population (FDEP, 2008), so it is important to know the fate and transport of Cu, Zn, Mn,

and Fe added with tomato packinghouse wastewater in soils, so as to protect groundwater

contamination. Presently, no information is available about the interaction of soil components

with the metals present in tomato packinghouse wastewater which can play an important role in

dictating leaching and/or mass accumulation of contaminants in the soil profile. The objective of

this study was to conduct leaching assessment of Cu, Fe, Mn, and Zn in a typical sandy soil of

Florida amended with packinghouse wastewater.

Materials and Methods

Study Site and Sample Collection

Soil used in column study was obtained from the Gulf Coast Research and Education

Center, University of Florida in Wimauma, FL (Latitude: 270 45' 44.13" N; Longitude: 820 13'

20.36" W). The soil at the site is somewhat poorly drained (seasonal water table 60 to 106 cm)

and the depth to the restrictive layer (Bh horizon) is more than 200 cm (USDA-NRCS, 2009b).

The soil at the site was zolfo fine sand series (sandy siliceous, hyperthermic oxyaquic alorthods)

which is the second most dominant series (7% of total area) in the study area (Hillsborough

County) after Myakka series (USDA-NRCS, 2009a). In the past, the site was under citrus

cultivation while for last 10 years, the site was not under cultivation. Soil samples were collected

from two distinct horizons: 1) Ap: disturbed surface soil horizon ranging from 0 to 17 cm, and 2)

A/E: transition subsurface horizon ranging from 17 to 50 cm. The collected soil samples were

separately air-dried for about 1-2 weeks and then manually sieved using a 2-mm sieve (US

sieve No. 10).

Column Preparation, Setup, and Equilibration

Soil columns were built by cutting a 30-cm internal diameter polyvinyl chloride (PVC)

pipe into 50-cm long section (total surface area: 730 cm2) using a modification of the






























0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
250
Calcium

S200


150


" 10 o Wastewater conc.
(47 mg L )

: 50

0

0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0



--- Control
Low
--- Medium
-- High


0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume
Figure 3-4. Concentration of P, Na, Ca, Mg, and K in leachate collected in four treatments
during 30 leaching events. Error bars indicate standard error of the mean.









high pH of solution while at low pH, the adsorption of P was decreased with increase in ionic

strength. The soil packed in soil columns had 12-14 mg L'1 water extractable P at soil to water

ratio of 1:10 (Table 3-5) and thus P recovered in leachate resulted from interaction of de-ionized

water with soil. During phase 2 and 3 (>1 PV), leachate P decreased to 0.2-0.3 mg L-1 in

wastewater treatments. The medium treatment that received same amount of water as control had

P concentrations between 0.2 and 0.4 mg L-1 during 30 leaching events. In high treatment,

leachate P increased from 0.4 to 0.6 mg L-1 till 1.9 PV and then remained constant for rest of the

study period (4.3 PV).

In our study, when additional P (4.2 mg L-1) was added via wastewater in the soil, P

concentration increased in the beginning (0.5-0.7 PV) due to the flow of pre-event water which

removed a measurable amount of P from the soil called "background P concentration" and

increased leachate P concentration. The decline in P concentration in later stages (till 1.1 PV)

coincided with the flow of wastewater in the leachate indicating that a part of the P added via

wastewater was fixed and thus soil acted as P sink as wastewater appeared in the leachate. This

suggests that our soil can buffer the P added with wastewater (total P: 4.2 mg L-1) by adsorbing it

in the soil and thus reducing the leachate concentration. Mamo et al. (2005) obtained the similar

results when wastewater (21 mg P L-1) was added in high P soil, which reduced P leaching.

According to Toor et al. (2005b), dissolved P in the solution can quickly adsorb onto soil

minerals as it penetrates onto soil aggregates. Therefore, most of the P added with wastewater

was not leached but retained in the soil.

The daily leachate P in all wastewater treatments was much below the wastewater P

concentration of 4 mg L-1 suggesting that most of the wastewater applied P was always sorbed in

the soil. According to Jensen et al. (1998), high ionic strength of wastewater can increase the P









leachate. However, leachate concentration of Na was always less than wastewater concentration

(358 mg L-) in all treatments indicating that a part of applied Na was fixed in the soil. This can

be attributed to the high sodium adsorption ratio (SAR) of the packinghouse wastewater (10.8) as

the higher values of SAR can result in preferential and greater adsorption of Na in the cation

exchange sites in soil than other divalent cations such as Ca and Mg (Robbins, 1984). According

to Leal et al. (2009), high SAR in water is expected to cause an increase in soil sodium

exchangeable percentage, enhancing the risk of sodification associated with soil structure

degradation. This may also result in water logging and decreased water infiltration. In our study,

similar percentage of water recovery in medium and high treatments may result from the reduced

infiltration in high treatment due to higher rate of Na application in the soil with wastewater.

However, Gloaguen et al. (2007) reported that behavior of Na in the soil solution depends

predominantly on the balance between adsorption and desorption processes at cation exchange

complex. In our study, most of the Na applied was adsorbed in the soil at the expense of Ca and

Mg desorption from soil exchange complex thus causing an increase in Ca and Mg concentration

in leachate.

Since Ca and Mg are divalent ions, they exhibit similar chemical properties, and as a result

show a very similar solute transport behavior in the coarse textured soil. In the control treatment,

de-ionized water leached small concentrations of Ca (11-36 mg L-1), Mg (1.8-7.2 mg L-1), and

K (5.2 to 8.7 mg L-1) in leachate (Figure 3-4). Similar concentrations were observed in

wastewater treatments during phase 1 (0.5-0.6 PV) suggesting that as the pre-event water/de-

ionized water infiltrates in the soil, some of the water soluble Ca, Mg, and K were leached from

the soil. As most of the Florida soils have originated from sandy marine deposits and limestone

minerals (Watts and Collins, 2008) such as calcite (CaC03), and dolomite [CaMg(C03)2], soils
















7.2

7.0

6.8


6.6

6.4


6.2

6.0
0.0


3.0 -


2.5


2.0


I 1.5


1.0


0.5


0.0
0.0




Figure 3-3.


0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Leachate pore volume
-4- Control -- Low-c- Medium -- High

Mean leachate pH and EC in soil columns in four treatments during 30 leaching
events. Error bars indicate standard error of the mean.


0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0









CHAPTER 3
LEACHING OF PHOSPHORUS AND CATIONS IN A SANDY SOIL IRRIGATED WITH
PACKINGHOUSE WASTEWATER

Introduction

Land application of agricultural and industrial waste products is the most common practice

to recycle solid and liquid wastes and improve physical and chemical properties of soils (Debosz

et al., 2002; Shiralipour et al., 1992). Although the commercial fertilizers are the major sources

of crop nutrients in the US and elsewhere, residual byproducts such as manures, biosolids,

composts, and animal and industrial wastewater effluents are routinely land applied

(VanWieringen et al., 2005). The application of these residuals at agronomic rates to the fields

that are close to sensitive water bodies or if applied at very high rates ( 50 Mg ha-) can impair

water quality (O'Connor et al., 2005). For instance, many water bodies in the US are phosphorus

(P) limited and the main sources of P are point such as wastewater discharge and non-point

sources such as leaching and runoff from landscape (Jensen et al., 1999). Since many of the

Florida soils are coarse textured, have low organic matter and limestone fractures, the vertical

movement (or leaching) of P to the groundwater is the main concern (Elliott et al., 2002; Reed et

al., 2006; Yang et al., 2007).

To characterize the leaching of contaminants in a soil and conduct risk assessment,

lysimeter techniques are widely used as they constitute closed loop systems and thus enable

control over water and solute percolating through the soil (Bergstrom, 1990; Weihermuller et al.,

2007). Different types of lysimeters include porous ceramic cups (Woodard et al., 2007),

homogenized packed lysimeters (Zhao et al., 2009), monolith undisturbed lysimeters, and field

based drainage systems (Algoazany et al., 2007; Gentry et al., 2007). Porous ceramic cups are

easy to install but they may adsorb considerable amounts of elements such as manganese (Mn),

nickel (Ni), and zinc (Zn) which may underestimate the concentration of metals in soil solution

41









Table 3-1. Pre-wetting/pre-event irrigation schedule in soil columns using de-ionized water
during July-August 2009
Irrigation event Application rate Depth of applied Leachate depth
water MeanSD Range
-cm day- cm
1 15 (1 PVt) 15 (1 PV) 1.35041 (8) 0.70-1.97
2 1.67 12 (0.8 PV) 7.260.32 (62) 6.45-7.62
3 1.67 12(0.8 PV) 8.870.2 (76) 1.22-1.30
4 1.67 12(0.8 PV) 9.650.21 (82) 9.16-9.88
tPV: Pore volume
1Values in parenthesis indicate percent recovery of applied water
Each of the irrigation events 2, 3, and 4 were conducted continuously for 7 days and leachate
was collected on day 8.

Table 3-2. Treatments applied in soil columns
Treatment Depth of irrigation Type of water
--cm day- -
Control 1.67 De-ionized water
Low 0.87 Wastewater
Medium 1.67 Wastewater
High 2.51 Wastewater
tFlorida Department of Environmental Protection-recommended rate of wastewater

Table 3-3. Selected physical properties of surface (0-17 cm) and subsurface (17-50 cm) soils in
the packed soil columns
Parameter Surface Subsurface
Sand (g kg-~) 924+1.3at 935+0.4a
Silt (g kg-) 741.3a 610.01a
Clay (g kg-1) 20.4a 40.4a
Bulk density (g cm3) 1.770.04b 1.870.02a
Particle density (g cm-3) 2.580.01b 2.620.1a
Porosity (%) 311.5a 280.9a
tMeanstandard deviation
Values followed by same letters in a row are not significantly different at P<0.05 using Fishers
LSD.


































2010 Maninder Kaur Chahal







as construction material for packinghouse waste stream, is composed of 10 to 12% chromium

(Cr) and <2% nickel (Ni). The resistance of stainless steel to rusting occurs because of the

protective passive coat of Cr as chromium trioxide which is impervious to air and water.

However, the halogens such as chloride can penetrate this oxide film causing corrosion and

release the metals in the water (Crawford et al., 1998). Eliades et al. (2004) observed release of

Ni (11 mg L-) and traces of Cr in stainless steel aging medium for a month under saline

conditions (w/v: 0.9%). Thus, at very low pH (2.7) and high chloride conditions, steel

constructed equipment may release Ni and Cr in the wastewater (Bohner and Bradley, 1991).

However, wastewater in most of the tomato packinghouses is maintained at neutral pH, so there

is less possibility of presence of Ni and Cr in the wastewater. In contrast to the available

information about the constituents and their likely sources in other wastewaters, no information

is available about the chemical composition of tomato packinghouse wastewater in Florida and

elsewhere. Our objective in this study was to characterize the chemical constituents present in

the tomato packinghouse wastewater. This information is critical to sustainably use

packinghouse wastewater in the environment.

Materials and Methods

Packing Operations in Packinghouses

In west-central Florida, there are two major tomato growing seasons: July-Dec and

Jan-April (Olson and Simonne, 2009). During each season, tomatoes are picked in two harvests,

usually 10-12 weeks after planting and packing of tomatoes is continued for about 1-2 months.

Field-harvested tomatoes are transported to the packinghouses for washing and sanitizing prior to

packing. The tomatoes are first dumped into a water flume system (also called "dump tank").

The rate at which tomatoes are added in the dump tanks is important to know as it determines the

flow of tomatoes through the packing line. For instance, the flow (and packing) of a specific









Concentrations of Trace Metals in Packinghouse Wastewater Applied to Soil Columns

Mean pH of the wastewater applied to soil columns was 6.2 while EC ranged from 1.94 to

2.44 dS m-1, with a mean value of 2.16 dS m-1. High EC in our wastewater was due to high

chloride which ranged from 551 to 638 mg L-1. Concentration of Cu was highest followed by Fe,

Mn and Zn (Table 4-5). Other trace metals such as B, Mo, and Cr had concentration <0.1 mg L'.

According to irrigation water quality guidelines (Ayers and Westcot, 1989), Fe and Zn in the

packinghouse wastewater were below the recommended limits while Cu (0.66 mg L-1) and Mn

(0.34 mg L-1) were higher than the recommended concentrations of 0.2 and 0.2 mg L-1 in

irrigation water, respectively (Table 4-5).

Leachate Volume in Soil Columns

After 30 leaching events, significant differences in mean leachate depth (cm day-1) were

observed in all treatments (Table 4-6). For instance, wastewater input was greatest in high (2.51

cm day-1) resulting in a greater drainage depth of 2.31 cm day-' (92% of applied water) followed

by medium and control (1.45-1.51 cm day-1 or 88-91%), and low (0.66 cm day-' or 79%)

treatments. Wastewater treatments exhibited variability in daily leachate volume with more

volume recovered in high followed by medium and low treatments due to variable amounts of

water application. Leachate to irrigation (LI) ratios in all treatments was <1 during 30 leaching

events indicating that a part of the applied water was always stored in the soil columns (Figure 4-

2A). The first eight leaching events showed a continuous and gradual increase in LI ratios from

0.70 to >0.85 in all treatments. Kleinman et al. (2005) observed that initial leaching events play a

significant role in the emergence and development of water flow paths in the soil and continuous

irrigation events can lead to apparent steady state flow in soil columns. In subsequent leaching

events, LI ratio was 0.86-0.96 in all but low treatment. The LI ratio increased simultaneously at

the end of the experiment and was 0.94 in high, 0.88-0.9 in medium and control, and 0.75 in low









compared to normal value of 3-9 highlighting severe limitations for wastewater use as an

irrigation source in the soil causing soil crust formation and/or reduced infiltration.

Wastewater application at medium application rate (1.67 cm per day) significantly

decreased the pH of leachate than the control treatment due to the flow of wastewater that had

low pH. Another possible reason for the low pH of solution can be the discharge of hydrogen

ions from the soil itself (pH=5.5-6) for the exchange of cations such as Na, Ca, and Mg from the

wastewater. This mechanism of cation-hydrogen exchange was similar to the action of cationic

resins (immobile solid particle) which are commonly used in wastewater to remove cations such

as Na and Ca from the solution and release hydrogen ions in the solution during ion exchange

(Ion Exchange Resin, 2010; Skogley and Dobermann, 1996). Application of wastewater at

medium rate (1.67 cm per day) resulted in increased EC of the leachate. Further increase in

application rate to 2.51 cm day-' (high) increased the EC significantly at P<0.05. Thus, the

source of irrigation (wastewater) as well as the application rate of irrigation water (0.87-2.51 cm

day-1) affected the leachate EC. Since the applied wastewater had relatively high ionic strength

(0.031 moles L-1) than de-ionized water, direct flow of wastewater in the soil columns resulted in

high EC in the leachate. The application of wastewater at medium and high treatments

significantly increased the mean leachate concentration of cations (Na, Ca, Mg, and K) in the soil

than the control while no effect was observed in mean P concentration (Table 3-10). The

maximum concentrations of Na (345-358 mg L-1) in leachate were greater than the Florida

groundwater cleanup target levels of 160 mg L-1 suggesting that high Na in the wastewater can

be a concern for the groundwater quality. The Ca, Mg, and K elements in leachate are not of

critical concern in Florida's surface waters and groundwater. The current experimental design







CHAPTER 2
WASTEWATER CHARACTERIZATION IN TOMATO PACKINGHOUSES

Introduction

Population growth and limited water resources have led to the practice of reusing

wastewater to meet irrigation needs in urban, agricultural, and industrial sectors in many US

states such as Florida, California, Texas, and Arizona. Florida is recognized as a national leader

in domestic wastewater reuse, boasting more than 3,400 Florida Department of Environmental

Protection (FDEP) permitted wastewater facilities (61% domestic, 39% industrial). These

facilities reclaim wastewater for a wide range of beneficial purposes such as landscape and

agricultural irrigation, groundwater recharge, and industrial uses (FDEP, 2010a). However, reuse

of wastewater presents a number of environmental and technical challenges.

For instance, high biological oxygen demand, high total soluble solids, and toxic chemical

residues requiring specialized treatment (O'Connor et al., 2008) are the major constraints to reuse

of wastewater generated by chemical industries. Similarly, wastewater generated by the 640 food

processing plants (e.g. tomato canning, meat packing, wine production, dairy processing) in

California's central valley is typically high in organic carbon, nitrogen (N), and iron (Fe) and

manganese (Mn) sulfates (California League of Food Processing, 2007). Wastewater from swine

lagoon facilities has high levels of nutrients particularly N (472 mg L-1) and phosphorus (P, 61

mg L-1) that require biological and chemical treatment (Szogi and Vanotti, 2009).

The sources of contaminants in the wastewater vary with the type of industry and the

associated cleaning operations in a facility. For instance, the common sources of copper (Cu) and

zinc (Zn) in domestic wastewater were reported to be from the residues of pesticides, corrosion

of pipes, wood preservatives, anti-fouling paints, and cosmetics (Firfilionis et al., 2004). In dairy

processing wastewater, main sources of P (71 mg L-1) were observed to be spillage of milk and

milk products, and use of P based cleaners such as phosphoric acid to clean equipment







350


300 v = 47.6x- 2.6 5
R2 =1

S250 -
250 v y= 36.3x-6.9
R2 = 0.994
a 200 -


S150 o Packinghouse 1
Packinghouse 2
S100 -


50-


0 W
0 1 2 3 4 5 6 7 8 9
Time (h)

Figure 2-1. Mean amount of washed tomatoes with time during four sampling events in each of
the two tomato packinghouses. Error bars indicate mean standard deviation.









Table 4-4. Total and water extractable contents of trace metals (mg kg-1) in two soil horizons in
the packed soil columns
Parameter Surface (0-17 cm) Subsurface (17-50 cm)
Total WE % recovery Total WE % recovery
Fe 45423at 40.6b 1 44619a 1 4a 3
Cu 60+3a 1.20.12a 2 80.4b 0.6+0.02b 7.5
Zn 276a 0.90.9a 3 4+lb 0.1+0.01a 2.5
Mn 262a 0.060.04 0.23 10.05b BD -
Cr 6+0.7a 0.050.01a 0.83 2+0.2b 0.1+0.02a 5
tMeanstandard deviation (N=3); BD: below detection
WE: Water-extractable
Values followed by same letters in a row are not significantly different at P<0.05 using Fishers
LSD

Table 4-5. Trace metal concentrations of packinghouse wastewater applied in the soil columns
Parameter Wastewater used in current study Wastewater collected Maximum
(August 2009) during May-June recommended
2009J concentration
MeanSDt Range Range
Cu 0.660.07 0.5-0.73 1.9-2.2 0.2
Fe 0.440.15 0.2-0.6 0.2-0.8 1
Mn 0.340.11 0.1-0.45 0.062-0.2 0.2
Zn 0.160.02 0.1-0.19 0.1-0.3 2
B 0.1+0.01 0.09-0.11 BD 3
Mo 0.090.01 0.1-0.09 0.02-0.04 0.01
Cr 0.050.01 0.04-0.06 0.01-0.06 0.1
t Standard deviation (N=6); BD: below detection
For details, see chapter 2
Ayers and Westcot (1989)

Table 4-6. Mean leachate volume of 30 leaching events in control and wastewater irrigated soil
columns
Treatment Application rate Mean drainage depth Recovery of applied
water
cm day-' %
Control 1.67 1.450.03bt 88
Low 0.84 0.660.la 79
Medium 1.67 1.510.01c 91
High 2.51 2.31+0.01d 92
tMeanstandard deviation
Values followed by same letters in a column are not significantly different at P<0.05 using
Fishers LSD.









Table 3-6. Selected chemical properties of packinghouse wastewater applied in the soil columns
Parameter Wastewater used in current study Wastewater collected
(August 2009) during May-June 2009
MeanSDt Range Range
pH 6.20.3 6-6.9 6.6-7.1
EC (dS m-) 2.160.23 1.9-2.4 1.3-2.8
Chloride (mg L-) 59334 551-638 255-1125
Sodium adsorption ratio 10.8+0.2 10.6-11


Elements (mg L')
Na 3
Ca z
K 3
Mg
P L
Al
tStandard deviation (N=6)
For details, see chapter 2
Below detection limits


5810
17+2
3+0.6
2+0.7
1.20.1
3D


349-377
45-50
32-34
21-23
4-4.4
BD


92-261
55-59
24-49
21-25
2.8-5.7
BD


Table 3-7. Mean leachate volume of 30 leaching events in control and wastewater irrigated soil
columns
Treatment Application rate Mean drainage depth Recovery of applied
water
cm day-' %
Control 1.67 1.450.03bt 88
Low 0.84 0.660.la 79
Medium 1.67 1.510.01c 91
High 2.51 2.31+0.01d 92
tMeanstandard deviation
Values followed by same letters in a column are not significantly different at P<0.05 using
Fishers LSD.

Table 3-8. Mean pH and EC values in leachate collected from four treatments in 30 leaching
events
Treatment Leachate pH Leachate EC (dS m1)
MeanSDt Range MeanSD Range
Control 6.91+0.01b 6.52-7.24 0.120.01a 0.06-0.41
Low 6.870.01ab 6.21-6.95 0.850.06b 0.1-2.52
Medium 6.530.01a 6.51-7.25 1.590.01c 0.11-2.82
High 6.440.04a 6.15-7.01 1.780.02d 0.11-2.81
t Standard deviation
Values followed by same letter in a column are not significantly different at P<0.05 using
Fishers LSD.









present in the soil. Soil organic matter and Fe oxides have been reported to have a high affinity

to fix Cu which is due to high surface complexation constants (Dzombak and Morel, 1990). Our

soil had high content of Fe in both horizons but soil organic matter was low in subsurface,

therefore organic fraction primarily fulvic acids in surface soil and Fe in both horizons may have

retained Cu as suggested by Lin et al. (2008) and Cao and Hu (2000).

In the control treatment, about 0.57 kg of Zn ha-' was leached as natural loss with de-

ionized water (Table 4-8). However, as wastewater application rate increased from low to high

treatment, leaching amounts of Zn increased from 0.62 to 2.12 kg ha- These leaching amounts

are equivalent to 159-185% of applied Zn in wastewater suggesting that additional 59-85% of

Zn was desorbed from the soil or previous accumulations of wastewater applied Zn. According

to Spellman (2008), some metals may be desorbed from the soil with increase in irrigation water

salinity and decrease in redox potential and pH. Thus, the greater loss of Zn in our study with

increase in wastewater application can be attributed to high EC and low pH of wastewater.

Among four metals, leaching losses of Fe were highest at 3.6 kg ha-1 in 30 leaching events

in control (Table 4-8). Leaching loss of Fe increased with increase in application rate of

wastewater. However, leaching loss as percentage of applied Fe in wastewater decreased due to

high background losses of Fe and retention of applied Fe in soil. Assuming the natural loss of Fe

from the soil (3.6 kg ha-1) in control treatment, a net loss of 1.64 kg Fe ha-1 in medium treatment

(that received same amount of water as control) occurred which is about 74% of applied Fe in

wastewater. A similar leaching behavior was observed for Mn (70% of applied Mn leaching in

medium treatment). Although the amounts of Mn leached in medium and high treatments were

similar (5.24-5.45 kg ha-1) at P <0.05, percentage leaching loss of Mn was greater in medium

(45%) than high (19%) treatment if we take into account the natural loss of Mn in control









soil may result from the formation of soluble metal complexes with organic acids, solvents or

chelating agents in soil. Davis and Singh (1995) reported that addition of chlorine can enhance

Zn removal from the soil due to oxidization of soil organic matter which can then release Zn

completed with organic matter. This seems to be the case in our study as wastewater was rich in

chloride. This suggests that additional Zn in leachate may have originated from Zn desorption

from the soil. Interestingly, the low treatment showed highest Zn as well as Fe and Mn

concentrations in leachate followed by medium and high treatments.

In contrast to increasing concentrations of Cu and Zn during phase 1, Fe and Mn showed a

sharp decrease till 0.5 PV, followed by constant concentrations (0.7-1.1 mg L-1) in medium and

high treatments and an increase in low treatment (Figure 4-3). The removal of Fe and Mn during

displacement of pre-event water could be due to presence of the reduced forms of Fe (ferrous)

and Mn in our low pH soil after saturation with water, which are more mobile than oxidized

forms (Lewis, 1995). During 30 leaching events, concentrations of Fe in leachate were greater

than the wastewater applied Fe concentrations of 0.2-0.6 mg L-1 indicating that significant

amount of Fe was removed from the soil. Concentrations of Mn showed a decreasing trend in all

treatments till 0.5 PV followed by an increase in wastewater treatments till 0.8-1 PV that

approached the mean applied wastewater Mn concentrations of 0.34 mg L-1. After 1 PV, Mn

decreased in leachate suggesting adsorption of Mn on Fe oxides or organic matter in soil profile

(Khattack and Page, 1992). According to Sposito (1989), the solubility of Mn in soils is highly

sensitive to changes in the soil redox conditions. Under slight to moderate saturated conditions,

Mn oxides are more susceptible to dissolution than Fe oxides and as a result dissolution of Mn

oxides precedes Fe. Xiang and Banin (1996) observed that a substantial fraction of the Mn









Table 4-1. Pre-wetting/pre-event irrigation schedule in soil columns using de-ionized water
during July-August 2009
Irrigation event Application rate Depth of Leachate depth
applied water MeanSD Range
-cm day- cm
1 15 15 (1 PV)t 1.350.41 (8) 0.70-1.97
2 1.67 12 (0.8 PV) 7.260.32 (62) 6.45-7.62
3 1.67 12 (0.8 PV) 8.870.20 (76) 1.22-1.30
4 1.67 12 (0.8 PV) 9.650.21 (82) 9.16-9.88
tPV: Pore volume
1Values in parenthesis indicate percent recovery of applied water
Each of the irrigation events 2, 3, and 4 were conducted continuously for 7 days and leachate
was collected on day 8

Table 4-2. Treatments applied in soil columns
Treatment Depth of irrigation Type of water
cm day-'
Control 1.67 De-ionized water
Low 0.87 Wastewater
Medium 1.67 Wastewater
High 2.51 Wastewater
tFlorida Department of Environmental Protection-recommended rate of wastewater

Table 4-3. Selected properties of surface (0-17 cm) and subsurface (17-50 cm) soils in the
packed soil columns
Parameter Surface Subsurface
Sand (g kg-1) 924+1.3at 935+0.4a
Silt (g kg-) 741.3a 610.01a
Clay (g kg- ) 20.4a 40.4a
Bulk density (g cm-3) 1.770.04b 1.870.02a
Particle density (g cm3) 2.580.01b 2.620.1a
Porosity (%) 311.5a 280.9a
pH 60.08a 5.50.01b
EC (dS m-) 0.0653a 0.03911lb
Organic matter (g kg-1) 231la 8+lb
tMeanstandard deviation
Values followed by same letters in a row are not significantly different at P<0.05 using Fishers
LSD.









Marion, G.M., and G.L. Babcock. 1976. Predicting specific conductance and salt concentration
in dilute aqueous solutions. Soil Sci. 122:181-187.

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bioavailability-based rationale for controlling metal and metalloid contamination of
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removal in an MBR treating municipal wastewater with special focus on biological
phosphorus removal. Bioresour. Technol. 101:3984-3991.

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63:64-72.







determine the combined effect of all factors on the concentrations of wastewater constituents.

The regression equations developed in step 1 (simple regression) indicates the effect of amounts

of washed tomatoes on concentrations of P, Cu, and Zn (Table 2-3). The significant R2 values

(0.3-0.9) in step 1 equations (tomatoes only) suggested that increasing the amounts of washed

tomatoes resulted in increased concentrations of P, Cu, and Zn. Stepwise linear regression

indicated that in addition to external factors (such as addition of tomatoes), wastewater chemistry

(chloride, EC, pH) resulted in increasing wastewater concentrations of some constituents such as

P. In step 2 (tomatoes and pH), pH did not show any effect on wastewater P and Cu in PKG 1

and Zn concentration in PKG 2 while in step 3 (tomatoes and chloride), R2 value increased

significantly for P and Cu in PKG 1. This indicates that high chloride in PKG 1 wastewater may

have elevated the P concentration in wastewater. We suggest that the high levels of chloride in

wastewater may have caused the release the P from damaged culls (tomato fruits) as tomatoes

are rich source of P (up to 70 mg kg-1). The significant R2 values in step 4 (tomatoes, pH, and

chloride) for P in two packinghouses suggested that tomatoes, pH, and chloride explain most of

the variability in wastewater P concentration. Overall, it is important to note that these equations

are applicable to a specific tomato packinghouse where the study was conducted. The

management practices such as type of tomatoes washed, growers with different cultivars,

operational hours of packing and sanitation practices varies in packinghouses and thus the

regression equations explaining the variability of wastewater constituents due to intrinsic and

extrinsic factors may also differ.

Implications of Using Packinghouse Wastewater in the Environment

According to FDEP rule 62-660.805 (Florida Administrative Weekly, 2006), a department

industrial wastewater permit is required for the disposal of tomato packinghouse wastewater if

volume is between 19, 000 and 190, 000 L day-1. Wastewater less than 19, 000 L of volume day-1









LIST OF FIGURES


Figure Page

1-1 Yearly fresh-market tomato production in US (VanSickle and Hodges, 2008). ..............18

1-2 Changes in water quality in the dump tank during cleaning of tomatoes in a tomato
p ack in g h ou se ...................................... ................................................. 19

2-1 Mean amount of washed tomatoes with time during four sampling events in each of
the two tomato packinghouses. Error bars indicate mean standard deviation .................37

2-2 Effect of cumulative amounts of washed tomatoes on wastewater EC and chloride
during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009........38

2-3 Effect of cumulative amounts of washed tomatoes on wastewater P, Cu, Zn, and Fe
during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009........39

2-4 Effect of cumulative amounts of washed tomatoes on wastewater Ca, Mg, and K
during four sampling events (labeled as S-1, S-2, S-3, and S-4) in May-June 2009........40

3-1 Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse ...............67

3-2 Leachate volume recovery and chloride breakthrough in soil columns during 30
leachin g ev ents ...................................... .................................................. 6 8

3-3 Mean leachate pH and EC in soil columns in four treatments during 30 leaching
events. Error bars indicate standard error of the mean. ................ ................ ..............69

3-4 Concentration of P, Na, Ca, Mg, and K in leachate collected in four treatments
during 30 leaching events. Error bars indicate standard error of the mean. ....................70

4-1 Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse ...............88

4-2 Leachate volume recovery and chloride breakthrough in soil columns during 30
leachin g ev ents ...................................... .................................................. 89

4-3 Mean concentration of trace metals in the leachate in four treatments during 30
leaching events in soil colum ns. ............................................................. .....................90









behavior of packinghouse wastewater contaminants in Florida soils is available. Further,

urbanization and the close proximity of packinghouses to environmentally sensitive water bodies

results in additional costs to packinghouses, which must comply with increasingly stringent

wastewater regulations. Because of rapid urbanization and lack of wastewater disposal sites near

packinghouses, many packinghouses spend considerable time and money to transport wastewater

to distant disposal sites. Thus, in order to provide recommendations for efficient packinghouse

wastewater management in terms of reducing contaminants at the source and preventing

groundwater contamination, the objectives of this study were:

Objectivel. Characterize the chemical composition of wastewater generated in tomato

packinghouses (see Chapter 2).

Hypothesis: Contaminant concentrations will increase with number of tomatoes washed.

Objective2. Assess the potential leaching of wastewater contaminants using soil columns

containing coarse textured (sandy soil) soil representative of Florida (see Chapter 3 and

Chapter 4).

Hypothesis: Application of wastewater to sandy soils will result in an increase in of

contaminant concentrations in the leachate.









mg L-1, Zn: 20 mg L-1, and Cu: 4 mg L-) than control. This was attributed to high clay content

(55%) and high cation exchange capacity (315 meq kg-1).

In contrast, Madrid and Barrientos (1998) observed that application of olive mill

wastewater (Cu: 35 mg L-1; Zn: 53 mg L-) to packed sandy lysimeters (12 cm long and 4 cm

wide) leached about 38% of Cu and 20% of Zn applied with wastewater and attributed this to the

solubilization of metals bonded with organic polymers by the flow of wastewater in soil. In a

recent study by Tijani (2009), application of domestic wastewater (Cu: 2 pg L-1; Zn: 2470 pg L

1) in perforated trays packed with sandy loam soil leached Cu with concentration of 6-11 pg L-1

while Zn was retained in soil with relatively low concentration in leachate (66 .g L-) than

wastewater input. The retention of Zn in the soil was attributed to attenuation, plant uptake, and

chelation-complexation reactions in soil. Thus, in addition to accumulation, significant leaching

of trace metals with applied wastewater may pose a risk of groundwater contamination with

these trace metals. The retention and/or leaching behavior of metals applied with wastewater are

primarily function of soil properties which includes clay content, organic matter, cation exchange

capacity, Fe and Mn oxides, and contents of previously retained metals (Mapanda et al., 2005;

Tam and Wong, 1996).

Ayers and Westcot (1989) recommended maximum concentration of Cu, Fe, Mn, and Zn

in irrigation water of 0.20, 1.0, 0.2, and 2 mg L-1, respectively. However, in our study,

wastewater samples collected from tomato packinghouses exceeded the recommended Cu and

Mn concentrations for irrigation water (see Chapter 2). As most of the Florida soils are typically

coarse textured in nature with shallow groundwater and high rainfall (130-150 cm per year).

Therefore, it is possible that land application of wastewater containing these metals may result in

groundwater contamination. Ground water is also the drinking water sources for 93% of the









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Table 3-9. Total amounts of P and cations (Na, Ca, Mg, and K) applied in the soil columns,
amounts, and percent leaching of applied amounts in four treatments in 30 leaching
events


Treatment P Na Ca Mg K
Amounts applied (kg ha-1)
Control 0 0 0 0 0
Low 11 898 119 55 82
Medium 21 1796 238 109 165
High 32 2708 359 165 248
Amounts leached (kg ha-1)
Control 3.01.4abt 0.790.3a 655a 12+la 294a
Low 0.560.2a 7017b 1308b 33lb 273a
Medium 1.5+1.lba 866 6c 3264c 895c 64+5b
High 4.160.4c 1658+23d 46310d 1147d 125+4c
LSDJ 1.75 27.17 13.29 8.42 7.55
Percent leached
Low 5 8 110 60 33
Medium 7.2 48 137 82 39
High 13 61 128 69 50
tMeanstandard deviation
Least significant difference at P<0.05
Values followed by same letter in a column are not significantly different at P<0.05 using
Fishers LSD.

Table 3-10. Mean leachate concentrations (mg L1) of P and cations in four treatments after 30
leaching events
Treatment P Na Ca Mg K
mgL-1


Control 0.70.3at 0.180.1a 151.3a 2.70.2a 71la
Low 0.280.1a 35+8b 66+4b 170.5b 14+1.2t
Medium 0.330.2a 1882c 71l1c 19.41.2c 141.1t
High 0.60.la 235+2d 66+2b 161lb 180.7(
LSDJ 0.41 7.91 4.83 1.60 1.96
tMeanstandard deviation
Least significant difference
Values followed by same letter in a column are not significantly different at P<0.05 using
Fishers LSD.









did not include plants so the effect of nutrient plant uptake was not taken into account, which

may modify the leaching behavior of some elements.

Summary

Application of packinghouse wastewater at medium rate (1.67 cm day-1) in a typical coarse

textured soil of Florida did not result in increased P leaching losses suggesting that packinghouse

wastewater can be safely land applied in the soils having similar chemical properties as in our

study. The high ionic strength (0.031 moles L-1) of wastewater resulted in enhanced P adsorption

on Al, Fe, and Ca sites in soil. In addition, a part of the applied Mg and K was also retained in

the soil. In contrast, wastewater application resulted in removal of Ca from the soil profile which

can be either native Ca in soil or past accumulations of wastewater applied Ca. Since most of the

P applied with packinghouse wastewater was fixed in the soil resulting in lower P leaching

losses, repeated applications of wastewater P may exceed the saturation capacity of soil or

saturation of P fixation sites in soil and eventually P leaching. Although the leaching losses of

Ca, Mg, Na, and K were elevated in high treatment that received wastewater at 2.51 cm per day,

in most of the Florida soils these nutrients are not of critical concern. Thus, from environmental

prospective, it makes sense to reuse packinghouse wastewater for land irrigation as this will not

result in increased losses of P; in fact, our results show that it reduced P leaching. The presence

of high Al, Fe, and Ca in our soil enhanced the adsorption of P. Wastewater application in soil

resulted in removal of Ca from the soil profile which can be either native Ca in soil or past

accumulations of wastewater applied Ca.









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WI.


101







(Danalewich et al., 1998). According to Toor et al. (2005a), diet P in dairy farms is the dominant

source of P in feces and thus, in dairy wastewater. Similarly, in swine effluent, the high P in diet

(corn, wheat) was also observed to be the primary source of P in the wastewater (Smith et al.,

2004).

Florida is a leading producer of field-grown fresh-market tomatoes in the US. The per

capital consumption of tomatoes is about 8 kg per year (Florida Tomato Committee, 2003). The

70 tomato packinghouses in Florida pack the field-grown tomatoes for domestic supply and

results in production of about 231 million L of wastewater per year in Florida. About 54% of this

wastewater is land applied in tomato fields and another 31% is disposed in city sewerage systems

(Florida Tomato Committee, 2007). According to Florida Administrative Code 62-302.530

(Florida Administrative Weekly, 2006), wastewater containing P and trace metals above

threshold levels needs to be treated prior to their discharge in the environment. Therefore, cost

effective and practically feasible strategies are needed for the safe disposal of tomato

packinghouse wastewater which may otherwise act as a source of contaminants in the

environment.

The knowledge about the chemical composition of wastewater produced in packinghouses

and their potential sources in the waste stream can help develop solutions to sustainably manage

wastewater in Florida. Wastewater produced in tomato packinghouses may contain different

chemical constituents such as P, Cu, and Zn. Elevated concentrations of elements especially P

and Cu in the wastewater may restrict its use in the environment due to strict wastewater

discharge regulations in Florida (FDEP, 2010b). The interaction of water with the dump tanks

may result in leaching metals and increasing their concentrations in wastewater. For instance,

Rule et al. (2006) reported that if water is kept stagnant for longer duration (24-48 h) in a tank, it

may leach metals such as Cu and Zn from the pipes. Similarly, stainless steel, a commonly used




Full Text

PAGE 1

1 TOMATO PACKINGHOUSE WASTEWATER: CHARACTERIZATION AND LEACHING STUDIES By MANINDER KAUR CHAHAL A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2010

PAGE 2

2 2010 Maninder Kaur Chahal

PAGE 3

3 This work is dedicated to my parents, brother, and sister. It would not have been possible without their love, support and encouragement.

PAGE 4

4 ACKNOWLEDGMENTS I would like to thank my committee chair, Dr. Gurpal Toor, for providing me with the opportunity to study a truly unique system, and for his guidance and help. The expertise of my committee members, Dr. Belinski Santos, Dr. Nkedi Peter Kizza and Dr. Geor ge J Hochmuth has been invaluable. I would like to thank the Environmental Protection Agency for supporting the research. Jose Moreno, farm manager at Gulf Coast Research and Education Center, was a tremendous help in the field. The lab staff at the Soil a nd Water Q uality laboratory and my fellow graduate students (Butch Bradley, Gitta Shurberg, Lu Han, Kamaljit Banger, Manmeet Warya, Pardeepinder Brar and Sushila Chaudhari ) ha ve been great friends as well as teachers. Last, but not least, I would like to thank my family and friends who have supported me in all my endeavors.

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ...............................................................................................................4 LIST OF TABLES ...........................................................................................................................7 LIST OF FIGURES .........................................................................................................................9 LIST OF ABBREVIATI ONS ........................................................................................................10 ABSTRACT ...................................................................................................................................12 CHAPTER 1 INTRODUCTION ..................................................................................................................14 Tomato Production Trends in the United States .....................................................................14 Water Use and Wastewater Production in Tomato Packinghouses ........................................15 Wastewater Suitability for Environmental Use ......................................................................15 Research Objectives ................................................................................................................16 2 WASTEWATER CHARACTERIZATION IN TOMATO PACKINGHOUSES .................20 Introduction .............................................................................................................................20 Materials and Methods ...........................................................................................................22 Packing Op erations in Packinghouses .............................................................................22 Wastewater Sample Collection ........................................................................................23 Laboratory Analysis ........................................................................................................24 Statistical Analysis ..........................................................................................................24 Results and Discussion ...........................................................................................................25 Amount of Tomatoes Packed in the Packinghouses ........................................................25 Chemical Characteristics of Municipal Water Used in Packinghouses ..........................25 Effects of Amounts of Tomatoes Packed on Wastewater EC and Chloride ...................25 Effects of Amounts of Tomatoes Packed on Wastewater Chemical Constituents ..........26 Factors Affecting Concentrations of P, Cu, and Zn in Packinghouse Wastewater .........28 Implications of Using Packinghouse Wastewater in the Environment ...........................30 Summary .................................................................................................................................33 3 LEACHING OF PHOSPHORUS AND CATIONS IN A SANDY SOIL IRRIGATED WITH PACKINGHOUSE WASTEWATER .........................................................................41 Introduction .............................................................................................................................41 Materials and Methods ...........................................................................................................44 Study Site and Sample Collection ...................................................................................44

PAGE 6

6 Column Preparation, Setup, and Equilibration ................................................................45 Treatments and Leachate Collection ...............................................................................46 Soil and Water Analysis ..................................................................................................47 Statistical Analysis ..........................................................................................................48 Results and Discussion ...........................................................................................................49 Physical and Chemical Properties of Soils ......................................................................49 Chemical Characteristics of Packinghouse Wastewater Applied to Soil Columns .........49 Leachate Volume in Soil Columns ..................................................................................50 Chloride Breakthrough in Wastewater Amended Soil Columns .....................................51 Leachate pH and EC in Control and Wastewater Amended Soil Columns ....................52 Transport of P, Na, Ca, Mg, and K in Soil Columns .......................................................53 Mass Balance of Constituents in Soil Columns ..............................................................58 Mean Concentrations of P, Na, Ca, Mg, and K in Leachate ...........................................58 Implications for Land Application of Packinghouse Wastewater ...................................59 Summary .................................................................................................................................61 4 LEACHING OF TRACE META LS IN A SANDY SOIL IRRIGATED WITH WASTEWATER ....................................................................................................................71 Introduction .............................................................................................................................71 Materials and Method s ...........................................................................................................73 Study Site and Sample Collection ...................................................................................73 Column Preparation, Setup, and Equilibration ................................................................73 Treatments and Leachate Collection ...............................................................................75 Soil and Water Analysis ..................................................................................................76 Statistical Analysis ..........................................................................................................77 Results and Discussion ...........................................................................................................77 Physical and Chemical Properties of Soils ......................................................................77 Concentrations of Trace Metals in Packinghouse Wastewater Applied to Soil Columns .......................................................................................................................78 Leachate Volume in Soil Columns ..................................................................................78 Chloride Breakthrough in Wastewater Amended Soil Columns .....................................79 Trace Metals Transport in Soil Columns Amended with Packinghouse Wastewater .....80 Mass Balances of Trace Metals in Wastewater Amended Soil Columns .......................82 Summary .................................................................................................................................84 5 SUMMARY, CONCLUSIONS, AND RECOMMENDATION ............................................91 LIST OF REFERENCES ...............................................................................................................94 BIOGRAPHICAL SKETCH .......................................................................................................103

PAGE 7

7 LIST OF TABLES Table Page 21 Selected chemical properties of municipal water used in the dump tanks in two tomato packinghouses before the cleaning of fieldharvested tomatoes ...........................35 22 Potential sources of P, Cu, Zn, and K in wastewater carried f rom washed tomatoes ........35 23 Simple and stepwise regression models for predicting concentrations of P, Cu, and Zn in wastewater (mg L1) with the amount of tomatoes washed (t), wastewater pH, and chloride (Cl) in two tomato packinghouses ................................................................36 24 Selected chemical properties of wastewater produced in the dump tanks in two tomato packinghouses at the end of packing operations ....................................................36 31 Pre wetting/pre event irrigation schedule in soil columns using de ionized water during July ...................................................................................................62 32 Treatments applied in soil columns ...................................................................................62 33 Selected physical properties of surface (0 the packed soil columns .....................................................................................................62 34 Selected chemical properties of surface (0 in the packed soil columns .................................................................................................63 35 Water extractable (soil to water ratio= 1:10) elements (mg kg1) in two soil horizons packed in the soil columns .................................................................................................63 36 Selected chemical properties of packinghouse wastewater applied in the soil columns ...64 37 Mean leachate volume of 30 leaching events in control and wastewater irrigated soil columns ..............................................................................................................................64 38 Mean pH and EC values in leachate collected from four treatments in 30 leaching events ..............................................................................................................................64 39 Total amounts of P and cations (Na, Ca, Mg, and K) applied in the soil columns, amounts, and percent leaching of applied amounts in four treatments in 30 leaching events ..............................................................................................................................65 310 Mean leachate concentrations (mg L1) of P and cations in four treatments after 30 leaching events ...................................................................................................................65 311 Guidelines for interpretation of water quality for irrigation purposes in agriculture (Ayers a nd Westcot, 1989) ................................................................................................66

PAGE 8

8 41 Pre wetting/pre event irrigation schedule in soil columns using de ionized water during July ...................................................................................................85 42 Treatments applied in soil columns ...................................................................................85 43 Selected properties of surface (0 packed soil columns ...........................................................................................................85 44 Total and water extractable contents of trace metals (mg kg1) in two soil horizons in the packed soil columns .....................................................................................................86 45 Trace metal concentrations of packinghouse wastewater applied in the soil columns ......86 46 Mean leachate volume of 30 leaching events in control and wastewater irrigated soil columns ..............................................................................................................................86 47 Mean leachate concentrations (mg L1) of trace metals in four treatments in 30 leaching events ...................................................................................................................87 48 Total amounts of trace metals (Cu, Fe, Mn, and Zn) applied in the soil columns, amounts leached, and percent leaching of applied amounts in four treatments in 30 leaching events ...................................................................................................................87

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9 LIST OF FIGURES Figure Page 11 Yearly fresh market tomato production in US (VanSickle and Hodges, 2008). ...............18 12 Changes in water quality in the dump tank during cleaning of tomatoes in a tomato packinghouse .....................................................................................................................19 21 Mean amount of washed tomatoes with time during four sampling events in each of the two tomato pa ckinghouses. Error bars indicate mean standard deviation. ..................37 22 Effect of cumulative amounts of washed tomatoes on wastewater EC and chloride during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May .......38 23 Effect of cumulative amounts of washed tomatoes on wastewater P, Cu, Zn, and Fe during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May .......39 24 Effect of cumulative amounts of washed tomatoes on wastewater Ca, Mg, and K during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May .......40 31 Arrangement of soil columns (30 cm wide and 50 cm long) in the gre enhouse ...............67 32 Leachate volume recovery and chloride breakthrough in soil columns during 30 l eaching events ...................................................................................................................68 33 Mean leachate pH and EC in soil columns in four treatments during 30 leaching events. Error bars indicate standard error of the mean. .....................................................69 34 Concentration of P, Na, Ca, Mg, and K in leachate collected in four treatments during 30 leaching events. Error bars indicate standard error of the mean. ......................70 41 Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse ...............88 42 Leachate volume recovery and chloride breakthrough in soil columns during 30 leaching events ...................................................................................................................89 43 Mean concentration of trace metals in the leachate in four treatments during 30 leaching events in soil columns. ........................................................................................90

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10 LIST OF ABBREVIATION S Al Aluminum As Arsenic B Boron Ca Calcium Cd Cadmium Co Cobalt Cr Chromium Cu Copper EC Electrical conductivity FDEP Florida Department of Environmental Protection Fe Iron ICP OES Inductively coupled plasma optical emission spectroscopy K Potassium LI Leachate irrigation LSD Least significant difference Mg Magnesium Mn Manganese Mo Molybdenum N Nitrogen Na Sodium Ni Nickel P Phosphorus Pb Lead PKG 1 Packin ghouse 1

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11 PKG 2 Packinghouse 2 PV Pore volume PVC Polyvinyl chloride SAR Sodium adsorption ratio Se Selenium Zn Zinc

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12 Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science TOMATO PACKINGHOUSE WASTEWATER: CHARACTERIZATION AND LEACHING STUDIES By Maninder Kaur Chahal August 2010 Chair: Gurpal Toor Major: Soil and Water Science As a result of urbanization, tomato packers in Florida often struggle to find ways to reuse the large volumes of wastewater generated during the tomato cleaning and sanitizing process H igh transportation costs for off site disposal and strict surface water discharge regulations ar e critical issues associated with the management of packinghouse wastewater in Florida. Information about the composition of packinghouse wastewater, likely sources of major wastewater constituents and effects of land application might provide insights to develop environmentally sust ainable practices for reuse of wastewater. The objectives of this study were to (1) characterize wastewater produced in tomato packinghouses and (2) evaluate the leaching potential of phosphorus and trace metals added with wastewater in the sandy soils typical in Florida Results showed that wastewater had high electrical conductivity (1.3 2.8 dS m1) and chloride (255 1125 mg L1) due to the use of chlorine gas as a sanitizer i n the packinghouses Co ncentrations of phosphorus (2.8 5.7 mg L1) and copper (1.9 2.2 mg L1) in wastewater increased during the tomato cleaning and sanitizing process The wastewater concentrations were above the threshold limits of 0.74 mg L1 for phosphorus discharge in Tampa Bay watershed area and 0.03 L1 for copper disch arge in groundwater supplies and irrigation water in agriculture. Analysis of l eachate collected from packed soil columns (50 cm long x 30 cm

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13 diameter ) irrigated with wastewater at three different application rates for 30 days ( 0.84, 1.67, 2.51 cm day1) showed that soil acted as a sink for phosphorus, copper, manganese, sodium, and potassium whereas calcium, magnesium, iron, and zinc applied with wastewater were not retained and were vertically transported to a depth of 50 cm The high ionic strength (0.031 moles L1) and high sodium adsorption ratio (10.8) of wastewater resulted in phosphorus and sodium adsorption in the soil. The application of wastewater at medium rate ( 1.67 cm day1) did not affect leaching behavior of phosphorus, copper, and iron whereas calcium, magnesium, potassium, manganese, and zinc losses were increased by 2 7 times as compared to the control Application of wastewater at the high rate (2.51 cm day1) increased the leaching losses of phosphorus and all metals by 1.3 3 times Th is result suggested that the long term application of wastewater at high rate can increase the l eaching of phosphorus and trace metals and can potentially cause groundwater contamination. However, our results show ed that packinghouse wastewater can be safe ly a pplied at sandy soils at 1.67 cm day1 without significant concern of increased phosphorus and copper leaching

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14 CHAPTER 1 INTRODUCTION Tomato Production Trends in the United States Tomatoes are one of the important vegetables consumed in the US. For instance, in 2007, approximately 1.87 billion kg of fresh market tomatoes were produced for domestic use in the US (VanSickle and Hodges, 2008). The vast majority (> 81% ) of these fresh market tomatoes were grown in the southeastern states (Alabama, Florida, Georgia, North Carolina, South Carolina, Tennessee, and Virginia) and California. Florida is the largest producer of fresh market tomatoes (650 m illion kg or 34% of total US production) that are grown on 15,300 ha with a total value of US $464 million. An estimated 90% of tomatoes grown in Florida are shipped out of the state to the eastern US and Canada (VanSickle and Hodges, 2008). However, s ince 1991, Florida has lost market share of tomatoes to other US producers such as California, who increased their production by 132 million kg (Figure 11). In addition, imports from other countries such as Mexico have taken an even greater share of the market from Florida producers than production increase s in other US states. D ue to variability in climatic conditions t omatoes are grown in Florida and other southeastern states from fa ll through spring (Aug and in California from spring through fall (Jan Aug) (Olson and Simonne, 2009; Strange et al., 2000). In Florida, tomatoes are predominantly grow n in Miami Dade C ounty, Southwest Florida the Palm Beach Fort Pierce region the Tampa B ay area, and the Panhandle west of Tallahassee. These areas have two main growing seasons in the year (Aug enough round slicing tomatoes along with Roma, grape and cherry types for the fresh market to meet the per capita consumption of 8 kg tomatoes per year (Florida Tomato Committee, 2003; Sargent et

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15 al., 2005). Thus, fieldgrown tomatoes in Florida are one of the main sources of tomatoes in Florida and the US. Water Use and Wastewater Production in Tomato Packinghouses There are approximately 70 tomato packinghouses in Flor ida that pack fresh market tomatoes (Agricultural Marketing Service, 2008). A typical packinghouse in Florida packs about 1.1 million kg of tomatoes in a day ( http://www.sixls.com/packing.php). P ackinghouses use large amounts of fresh water to fill dump tanks used for rinsing, washing, and sanitizing field harvested tomatoes before packing and the amount of water required d epend s on the type of tomatoes. For instance, the amount of water used for cleaning round tomatoes typically ranges from 36,000 to 68,000 L day1 while Roma and grape tomatoes require only 3,700 to 28,400 L day1Wastewater Suitability for Environmental Use (Florida Tomato Committee, 2007). Most packinghouses in Florida fill dump tanks (Figure 12A) with fresh water from the municipal supply before the beginning of packing house operation each day and drain the wastewater from t he dump tanks at end of the day. This water is continuous ly recirculat ed in the dump tanks where field tomatoes are dumped and washed during a typical 6 to 8 h of packing in a day (Figure 12B). At end of packing operation, approximately 3,800 to 18,200 L per day of wastewater is produced in the dump tanks (Florida Tomato Committee, 2007). This equates to about 231 million L of wastewater each ye ar in tomato packinghouses in Florida (S. Sargent, personal communication), which needs to be disposed in an environmentally sustainable way. According to a survey of Florida packinghouses, wastewater produced i s mainly disposed in three ways: 1) land application in agricultural fields (54%), 2) discharge into sewage systems (31%), and 3) no disposal or third party disposal (15%) (Florida Tomato Committee, 2007). Land application of wastewater in agricultural fie lds is a very convenient method of beneficially

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16 recycling the water and is widely used for various types of wastewater such as from animal operations, industrial, and domestic sectors (Bradford et al., 2008; Duan et al., 2009; Heidarpour et al., 2007; Scot t et al., 2004). This use of wastewater can reduce the pressure on freshwater supplies for irrigation and can provide beneficial plant nutrients, and improve soil conditions (Debosz et al., 2002; Shiralipour et al., 1992). Moreover, this wastewater applica tion can reduce the need to use fresh water to keep the tomato farm roads navigable in dry weather. There is a lack of knowledge on impact of land application of wastewater on groundwater contamination with phosphorus (P) and trace metals (such as copper, zinc) (Bradford et al., 2008; Duan et al., 2009). Further, urbanization and the close proximity of packinghouse to Floridas sensitive water bodies is especially problematic as the packers need to comply with increased regulations on using wastewater onsi te or disposing of in city sewerage systems. All these factors result in additional cost to packers. Information about the concentrations of nutrients and trace metals in wastewater (and their likely sources) together with leaching potential of contaminant s might provide ways to safely use wastewater in the environment and reduce the operational costs of managing wastewater in packinghouses. No information is available about the different contaminants present in wastewater and their leaching potential when wastewater is land applied. Research Objectives Currently, the tomato industry in Florida is facing the dilemma of balancing economic viability and environmental susta inab ility, and critical issues tied to wastewater disposal have the potential to undermi ne the sustainability of the tomato industry in Florida. In Florida, land application of tomato packinghouse wastewater is the most commonly practiced method of wastewater disposal. However, coarse texture, low organic matter, limestone fractures, and shal l ow groundwater table in most Florida soils may pose a risk to groundwater quality in terms of contaminant leaching. To the best of our knowledge, no scientific data on the leaching

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17 behavior of packinghouse wastewater contaminants in Florida soils is avai l able. Further, urbanization and the close proximity of packinghouse s to environmentally sensitive water bodies results in additional costs to pack inghouses, which must comply with increasingly stringent wastewater regulations. Because of rapid urbanization and lack of wastewater disposal sites near packinghouses, many packinghouses spend considerable time and money to transport wastewater to distant disposal sites. Thus, in order to provide recommendations for efficient packinghouse wastewater manage ment in terms of reducing contaminants at the source and preventing groundwater contamination, the objectives of this study were: Objective1 Characterize the chemical composition of wastewater generated in tomato packinghouses (see Chapter 2). Hypothesis : C ontaminant c oncentrations will increase with number of tomatoes washed. Objective2. Assess the potential leaching of wastewater contaminants using soil columns containing coarse textured (sandy soil) soil representative of Florida (see Chapter 3 and Chapter 4). Hypothesis: Application of w astewater to sandy soils will result in an increase in of contaminant concentrations in the leachate.

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18 Year 1992 1994 1996 1998 2000 2002 2004 2006 2008 Tomato production (million kg) 300 400 500 600 700 800 900 1000 California Florida Rest of US Figure 1 1. Yearly fresh market tomato production in US (VanSickle and Hodges, 2008)

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19 A B C Figure 1 2. Changes in water quality in the dump tank during cleaning of tomatoes in a tomato packinghouse: (A) clean water is added to dump tank before beginning of packing operation, (B) tomatoes are cleaned and sanitized, and (C) wastewater is produced at end of the day

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20 CHAPTER 2 WASTEWATER CHARACTER IZATION IN TOMATO PACKINGHOUSES Introduction Population growth and limited water resources have led to the practice of reusing wastewater to meet irrigation needs in urban, agricultural, and industrial sectors in many US states such as Florida, California, Texas, and Arizona Florida is recognized as a national leader in domestic wastewater reuse, boasting more than 3,400 Florida Department of Environmental Protection (FDEP ) permitted wastewater facilities (61% domestic, 39% i ndustrial) These facilities reclaim wastewater for a wide range of beneficial purposes such as landscape and agricultural irrigation, groundwater recharge, and industrial uses (FDEP, 2010a). However, r euse of wastewater presents a number of environmental and technical challenges. For instance, high biological oxygen demand, high total soluble solids, and toxic chemical residues requiring specialized treatment (O'Connor et al., 2008) are the major constraints to reuse of wastewater generated by chemical industries Similarly, wastewater generated by the 640 food processing plants (e.g. tomato canning, meat packing, wine production, dairy processing) in Californias central valley is t ypically high in organic carbon, nitrogen (N), and iron (Fe) and manganese (Mn) sulfates (California League of Food Processing, 2007). Wastewater from swine lagoon facilities has high levels of nutrients particularly N (472 mg L1) and phosphorus (P, 61 mg L1The sources of contaminants in the wastewater vary with the type of industry and the associated cleaning operations in a facility. For instance, the common sources of copper (C u) and zinc (Zn) in domestic wastewater were reported to be from the residues of pesticides, corrosion of pipes, wood preservatives, anti fouling paints, and cosmetics (Firfilionis et al., 2004). In dairy processing wastewater, main sources of P (71 mg L ) that require bi ological and chemical treatment (Szogi and Vanotti, 2009). 1) were observed to be spillage of milk and milk products, and use of P based cleaners such as phosphoric acid to clean equipments

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21 (Danalewich et al., 1998). According to Toor et al. (2005a ), diet P in dairy farms is the dominant source of P in feces and thus, in dairy wastewater. Similarly, in swine effluent, the high P in diet (corn, wheat) was also observed to be the primary source of P in the wastewater (Smith et al., 2004). Florida is a leading producer of fieldgrown fresh market tomatoes in the US. T he per capita consumption of tomatoes is about 8 kg per year (Florida Tomato Committee, 2003). The 70 tomato packinghouses in Florida pack the fieldgrown tomatoes for domestic supply and results in production of about 231 million L of wastewater per year in Florida. About 54% of this wastewater is land applied in tomato fields and another 31% is disposed in city sewerage systems (Florida Tomato Committee, 2007). According to Florida Administrative Code 62302.530 (Florida Administrative Weekly, 2006), wast ewater containing P and trace metals above threshold levels needs to be treated prior to their discharge in the environment. Therefore, cost effective and practically feasible strategies are needed for the safe disposal of tomato packinghouse wastewater wh ich may otherwise act as a source of contaminants in the environment. The knowledge about the chemical composition of wastewater produced in packinghouses and their potential sources in the waste stream can help develop solutions to sustainably manage wastewater in Florida. Wastewater produced in tomato packinghouses may contain different chemical constituents such as P, Cu, and Zn. Elevated concentrations of elements especially P and Cu in the wastewater may restrict its use in the environment due to s trict wastewater discharge regulations in Florida (FDEP, 2010b). The interaction of water with the dump tanks may result in leaching metals and increasing their concentrations in wastewater. For instance, Rule et al. (2006) reported that if water is kept s tagnant for longer duration (24 may leach metals such as Cu and Zn from the pipes. Similarly, stainless steel, a commonly used

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22 as construction material for packinghouse waste stream, is composed of 10 to 12% chromium (Cr) and <2% nickel (Ni). The resistance of stainless steel to rusting occurs because of the protective passive coat of Cr as chromium trioxide which is impervious to air and water. However, the halogens such as chloride can penetrate this oxide film causing corrosion and re lease the metals in the water (Crawford et al., 1998). Eliades et al. (2004) observed release of Ni (11 mg L1Materials and Methods ) and traces of Cr in stainless steel aging medium for a month under saline conditions (w/v: 0.9%). Thus, at very low pH (2.7) and high chloride c onditions, steel constructed equipments may release Ni and Cr in the wastewater (Bohner and Bradley, 1991). However, wastewater in most of the tomato packinghouses is maintained at neutral pH, so there is less possibility of presence of Ni and Cr in the wa stewater. In contrast to the available information about the constituents and their likely sources in other wastewaters, no information is available about the chemical composition of tomato packinghouse wastewater in Florida and elsewhere. Our objective in this study was to characterize the chemical constituents present in the tomato packinghouse wastewater. This information is critical to sustainably use packinghouse wastewater in the environment. Packing Operations in Packinghouses In west central Florida, there are two major tomato growing seasons: July Jan usually 10 t 1 Field harvested tomatoes are transported to the packinghouses for washing and sanitizing prior to packing. The tomatoes are first dumped into a water flume system (also called dump tank). The rate at which tomatoes are added in the dump tanks is important to know as it determines the flow of tomatoes through the packing line. For instance, the flow (and packing) of a specific

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23 amount of tomatoes will be slower for tomatoes dumped at 60 than 30 second intervals in the dump tank. Each day, the dumping rate in packinghouse is adjusted manually to accommodate the degree of sorting and grading for each lot of tomatoes at the packing counter. In addition, clean water was sometimes added during the operations to compensate the water loss due to spillage. To avoid the cross contamination of pathogens during washing in the dump tank, sanitizers such as chlorine gas, are constantly added in the water to maintain at 150 1Wastewater Sample Collection of free chlorine in the waste stream at water pH of 6.5 to 7.5 (Bartz et al. 2009). The packing operation typically lasts 6 to 8 h in a day. Wastewater samples from two major tomato packinghouses (hereafter referred to PKG 1 and PKG 2) were collected during May June 2009, which refers to the packing s eason of tomatoes grown in Jan packing varied from 6 (PKG 2) to 8 (PKG 1) h. The variability in operational hours is due to the variable amounts of tomatoes that need packing on a given day and allocation of different lots of tomatoes with variable size and quality from different growers that require different flow time in the waste stream. For each of the two packinghouses, four sampling events (referred to as S S e conducte d on a weekly basis during May June 2009. During each sampling event, municipal water or fresh water samples were collected from the dump tanks in 250 mL plastic bottles before the beginning of packing operations. After the start of packing opera tions, wastewater samples from the end of the water stream were collected at 30 min intervals for about 6 and analyzed. The amounts of tomatoes packed in each 30 min interval were calculated by recording the rate of dumping i.e. time taken to wash one bin that contained 454 kg of tomatoes throughout the packing day.

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24 454 tomatoes) of kg 454 per (minutes dumping of Rate (minutes) interval Time (kg) packed tomatoes of Amount Laboratory Analysis About 100 mL of wastewater sample was preserved for P and trace metals us ing conc. H2SO4 to pH <2 and stored at 40C until analysis. The remaining 150 mL of unpreserved sample was left on shelves until they attained room temperature. Then, pH and electrical conductivity (EC) in unpreserved samples were measured using a digital m eter (Accumet XL 60, Dual channel pH/ion/conductivity/dissolved oxygen meter, Fisher Scientific, Pandan Crescent, Singapore). Chloride in the wastewater was determined using a discrete analyzer (AQ2+, Seal Analytical Inc, Mequon, WI). Total P and 18 metals including aluminum (Al), arsenic (As), boron (B), calcium ( Ca ) ,cadmium (Cd), cobalt (Co), Cr, Cu, Fe, potassium ( K ) magnesium ( Mg ) Mn, molybdenum (Mo), sodium ( Na ) Ni, P, lead ( Pb ), s e lenium (Se) and Zn in the wastewater samples were determined using inductively coupled plasma optical emission spectroscopy (ICP OES) (PerkinElmer Optima 2100 DV; PerkinElmer, Shelton, CT) (USEPA method 200.7, 1985). Among 18 trace metals, 11 metals (Al, As, B, Cd, Co, Cr, Mo, Mn, Ni, Pb, and Se) were below the detection limits of ICP OES and therefore are not reported. Concentrations of Na were typically between 16 to >50 mg L1Statistical Analysis in the wastewater. Mean, standard deviation, and range for the concentration of different parameters in wastewater samples w ere calculated in Microsoft Excel 2007. Correlation matrix was established between the different constituents at 0.05 probability level using DATA analysis program in Microsoft Excel. Simple and stepwise linear regression was performed using Statistix vers ion 8.0 software with LINEAR MODELS procedure.

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25 Results and Discussion Amount of Tomatoes Packed in the Packinghouses Over four sampling events, an average of 305 Mg of tomatoes were packed in 8h in PKG 1 while 287 Mg of tomatoes were packed in 6h in PKG 2 (Figure 2 1). Most of the tomatoes packed in PKG 1 duri ng first 6 h of operation were R oma tomatoes (average weight: 102121 g) while round tomatoes (average weight: 170252 g) were packed during the last 12 h of packing operation in a day (North Carol ina Agricultural Research Service, 2002; Scott et al., 2009). In contrast, in PKG 2, only round tomatoes were packed. As a result of different type of tomatoes, the rate of dumping in the dump tanks varied from 55 t omatoes (PKG 1) to 29 40 second per 454 kg of large sized round tomatoes (PKG 2). This variability in types of tomatoes resulted in greater contact time of tomatoes with dump tank water in PKG 1 than PKG 2 and lower rate of tomato packing in the former (38 Mg per h) than the latter (48 Mg per h) packinghouse. Chemical Characteristics of Municipal Water Used in Packinghouses As municipal water was used in the dump tanks of both packinghouses to wash and sanitize the field harvested tomatoes, the pH (7.1 7.2) and EC (0.381Effects of Amounts of Tomatoes Packed on Wastewater EC and Chloride ) of water was similar. The concentrations of all chemical constituents such as chloride, P Ca, Mg, K, Cu, Fe, and Zn in the muni cipal water were similar in two packinghouses (Table 2 1) as both packinghouses were located in a c lose proximity with each other and had the same source of municipal water. Concentrations of EC and chloride in wastewater continuously increased as more tomatoes were washed (Figure 2 2). However, the magnitude of increase was much greater in PKG 1 than PKG 2. For instance, in PKG 1, EC increased from 0.4 to 1.2 1 and chloride increased from 24 to 3751 after washing 50 Mg of tomatoes. In contrast, EC and chloride were

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26 <1 d S m1 and <200 mg L1Effects of Amounts of Tomatoes Packed on Wastewater Chemical Constituents in PKG 2 wastewater after washing 50 Mg of tomatoes. The increase in EC and chloride in both packinghouses was attributed to the use of sanitizers such as chlorine dioxide and chlorine gas in the dump tanks. In PKG 1, after 200 Mg of tomatoes were washed in S 4, EC and chloride in the wastewater increased at relatively higher rate during the last 2 h which may be due to the c hange in type of tomatoes from R oma to round in the dump tanks. Overall, EC and chloride trends showed much less variability among four sampling events in PKG 2 than PKG 1. This may be due to more controlled conditions in PKG 2 than in PKG 1. For instance, in PKG 1 chlorine gas in the water stream were manually added from pressurized gas cylinders depending upon pH and oxidationreduction potential. Measurements of chlorine concentrations and water pH were also taken manually on an hourly basis to verify proper functioning of operations. However, in PKG 2, chlorine dioxide addition was automated in the water stream to maintain the optimum water pH (6.5 the washing operations due to technical problems in dumping machine, crowding of tomatoes at the packing counter and/or shifting of tomatoes from smallsized R oma to large siz ed round observed in PKG 1 may have also contributed to greater variability in EC and chloride than PKG 2. Concentrations of P, Cu, Zn, and Fe in wastewater increased as more tomatoes were washed in two packinghouses (Figure 23). As with EC and chloride, P, Zn, and Fe concentrations showed a similar pattern of greater concentrations and more variability during four sampling events in PKG 1 than in PKG 2 while magnitude and variability of Cu increase was similar in two packinghouses. Concentration of Zn in the wastewater was greater in PKG 1 than PKG 2 during all sampling events and the magnitude of increase in Zn concentrations was more pro nounced in the former than latter packinghouse. Wastewater Zn concentration increased

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27 with slope <0.001 in four sampling events while in PKG 2, slope of Zn increase was relatively low (<0.0003) which indicated that even with an increase in number of tomatoes washed, concentration of Zn in the wastewater remained almost constant in PKG 2. The concentrations of Fe in the wastewater were more variable and greater during four sampling events in PKG 1 than in PKG 2. Greater contact time of tomatoes with water in PKG 1 (55 (29 PKG 1 wastewater. Similarly, concentrations of Ca, Mg, and K in the wastewater increased as more tomatoes were washed in all sampling events in two packinghouses (Figure 24). In PKG 1, wastewater Ca increased linearly with relatively higher slope (0.15) in S 2 than other 3 sampling events (0.05 beginning w hen 25 except S 2 where Ca concentration continued to increase gradually till 200 Mg of tomatoes were washed. Thereafter, Ca concentration increased from ~40 to >50 mg L1 at relatively higher slopes as 276 Mg of tomatoes were washed. Concentrations of Mg and K were greater in PKG 1 than PKG 2 while in PKG 2, there was less variability during four sampling events than PKG 1 For instance, in PKG 1 the slope of Mg increase in four sampli ng events varied from 0.02 in S 1 to 0.04 in S 2 while in PKG 2, slope of Mg increase was about similar in all sampling events (0.02) with lower concentrations than PKG 1. In case of wastewater K, the slope of increase varied from low (0.080.1) in S 1 and S 3 to relatively high (0.2) values in S 2 and S 4 events in PKG 1 While in PKG 2, slope of increase was about similar with mean slope of 0.07 with concentrations lower than PKG 1 indicating the variability of Mg and K concentrations in wastewaters produ ced in two packinghouses.

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28 Factors Affecting Concentrations of P, Cu, and Zn in Packinghouse Wastewater A linear increase in concentrations of all chemical constituents in the wastewater with increase in amounts of tomatoes washed (Figures 23 and Figure 2 4) indicated that these constituents were carried from tomato fields as residues on fruits, leaves, or stems. The likely source of these contaminants in wastewater may include residues of foliar applications of insecticides, fungicides, and micronutrients (Cu, Zn) on tomato crop which on washing in packinghouse may have elevated their concentrations in wastewater. Although the primary focus of this study was to characterize the wastewater quality in packinghouses, a number of likely sources have been sugges ted herein to explore the scope of future research to identify sources of these constituents in wastewater. In Florida, a variety of organophosphate insecticides with active ingredients dimethoate, malathion, and methadiphos are foliarly applied on tomato crop to control aphids, mites, white flies, and earthworms (Table 22) (Olson and Simonne, 2009). In a study by Stevens and Kilmer (2009), tomato fruits collected from field were analyzed for residues of insecticides and about 52% of the samples showed res idues of methadiphos with maximum concentration of 0.56 mg L1. This suggests that insecticidal residues can get transferred from the tomato fruits to the water used for washing tomatoes, and can affect the wastewater quality in packinghouses. Similarly, foliar applied fungicides containing mono and di K salts of phosphorus acid to manage powdery mildew and Phytopthora species may also leave residues on the tomato fruits and foliage parts (leaves, stems) which may act as source of P and K in the wastewater. The Cu based fungicides (Cu hydroxide or Cu sulfate as active ingedient) are frequently used in foliar application in tomato crops against anthracnose and early blight, and are sometimes applied 1 harvesting. The foliar application of fungicides containing Zn salts (e.g. Mancozeb and Ziram) against ant hracnose, early blight, and grey leaf spot and fungicidies containing K such as K

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29 bicarbonate may tranfer Zn and K residues to the wastewater. In addition, residues of foliar applied Cu and Zn as micronutrient in plants may also be a likely source of waste water Cu and Zn. As tomato beds in Florida are covered with a plastic sheet, there is a neglegible risk of soil particles deposition on tomato plants. However, the splashing effect of frequent rain on the exposed soil, in between covered beds, can potenti ally contaminate some of the tomato fruits, or foliage with soil particles immediately or during harvesting. D uring the wastewater sample collection period (May (>30 cm) which may have caused fruit contamination due to splashing of soil particles. The bins used in tomato fields to pick up harvested tomatoes may contaminate the produce with soil particles to some extent from previous loads. In Florida, the macronutrients such as P and K are either directly incorporated in soil or applied with irrigation water in the crop root zone. The foliar sprays of P and K are not preferred as the leaves cannot absorb sufficient quantities of these nutrients (without burning) to correct their defic iency in plants or soil. Therefore, some of the applied P and K can be accumulated in soil and thus, deposition of eroded soil particles (containing P and K) on tomato fruits and foliage may contaminate the water which comes in their contact during the was hing operations. However, we do not have information whether soil particles contributed any of these metals to wastewater In two packinghouses, significant correlation of coefficient values of 0.41 amounts of washed tomatoes and chemical constituents such as P and Cu in wastewater indicated that tomatoes can explain about half of the variability in P and Cu conce ntrations except for Zn in PKG 2. In addition to external factors (amounts of washed tomatoes), wastewater internal factors (chloride or pH) may also result in elevated concentrations of these constituents (P, Cu, and Zn) in wastewater. Therefore, the step wise linear regression equations were developed to

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30 determine the combined effect of all factors on the concentrations of wastewater constituents. The regression equations developed in step 1 (simple regression) indicates the effect of amounts of washed tom atoes on concentrations of P, Cu, and Zn (Table 23). The signficant R2 values (0.3 tomatoes resulted in increased concentrations of P, Cu, and Zn. Stepwise linear reg ression indicated that in addition to external factors (such as addition of tomatoes), wastewater chemistry (chloride, EC, pH) resulted in increasing wastewater concentrations of some constituents such as P. In step 2 (tomatoes and pH), pH did not show any effect on wastewater P and Cu in PKG 1 and Zn concentration in PKG 2 while in step 3 (tomatoes and chloride), R2 value increased significantly for P and Cu in PKG 1 This indicates that high chloride in PKG 1 wastewater may have elevated the P concentrati on in wastewater. We suggest that the high levels of chloride in wastewater may have caused the release the P from damaged culls (tomato fruits) as tomatoes are rich source of P (up to 70 mg kg1). The significant R2Implications of Using Packinghouse Wastewater in the Environment values in step 4 (tomatoes, pH, and chl oride) for P in two packinghouses suggested that tomatoes, pH, and chloride explain most of the variability in wastewater P concentration. Overall, it is important to note that these equations are applicable to a specific tomato packinghouse where the stud y was conducted. The management practices such as type of tomatoes washed, growers with different cultivars, operational hours of packing and sanitation practices varies in packinghouses and thus the regression equations explaining the variability of waste water constituents due to intrinsic and extrinsic factors may also differ. According to FDEP rule 62660.805 (Florida Administrative Weekly, 2006), a department industrial wastewater permit is required for the disposal of tomato packinghouse wastewater if volume is between 19, 000 and 190, 000 L day1. Wastewater less than 19, 000 L of volume day1

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31 is exempted from the requirement of the permits provided they meet all surface water quality st andards. The chemical composition of wastewater at end of the packing operation showed elevated concentrations of all elements but the magnitude of increase was much greater for some elements (Table 2 2). Wastewater pH was maintained in the neutral range ( 6.5 recommended for Florida packinghouse waste stream (Bartz et al., 2009) and these values suggest that wastewater is suitable for irrigating most crops without any adverse effects on crop and soil properties (Ayers and Westcot, 1989). The pH is als o in the recommended range for Florida class IV agricultural water use (Florida Administrative Weekly, 2006). However, the EC showed marked increase in wastewater and was much greater in PKG 1 (2.8 dS m1) than PKG 2 (1.3 dS m1) due to much greater chloride (1125 mg L1) in PKG 1 than PKG 2 (255 mg L1). Significant correlation of EC with chloride in our study (r = 0.95) indicated that increased chloride in PKG 1 than PKG 2 resulted in relatively higher EC in PKG 1 wastewater than PKG 2. The high EC in the wastewater (especially of PKG 1) may pose slight to moderate restrictions for its use as irrigation water for salt sensitive crops such as strawberry, onions, and beans (Ayers and Westcot, 1989). The EC in our wastewater was comparable to dairy wast ewater (3.1 dS m1) but much lower than poultry lagoon wastewater (7.9 dS m1) (Bradford et al., 2008). Chloride in the wastewater was much elevated in PKG 1 (1125 mg L1) because of the manual control on chlorine addition in dump tank. According to Bartz et al. (2009), when chlorine is dissolved in water, it readily forms hypochlorous acid and hypochlorite ion (OCl-). Thus, three forms of chlorine (Cl2, HOCl, and OCl-) are present in aqueous chlorine solution which readily oxidizes organic compounds with different redox potentials and generate chloride ions in the solution (Fukayama et al., 1986) as follows:

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32 OH Cl e O H OCl Cl e Cl O H Cl H HOClV V V2 2 2 2 2 290 0 2 36 1 2 2 49 1 All chemical constituents showed a greater magnitude of increase in PKG 1 wastewater than PKG 2 due to greater contact time of tomatoes with water which was 55 1 and 32second in PKG 2 per 454 kg of dumped tomatoes (Table 2 4). Among all metals, the greatest increase was observed for Cu whose concentrations increased from 0.01 mg L1 in municipal water to 1.9 2.2 mg L1 in wastewater. Among trace metals, Cu concentration was above the threshold limit of 0.03 mg L1 for grounwater discharge and 0.5 mg L1 for irrigation water in agriculture (Florida Administrative Weekly, 2006) while other trace metals such as F e and Zn were below the threshold limits of 1 mg L1Concentrations of P in wastewater increased from <0.27 mg L for irrigation water. Therefore, wastewater may need to be treated to remove Cu before discharging into city sewers. 1 to 2.8 (PKG 2) 1) mg L1. The concentration of P in our wastewater was similar to that of municipal wastewater (2.51) (Moncls et al., 2010) and potato processing wastewater (3.4 mg L1) (Zvomuya et al., 2006) while Szogi & Vanotti (20 09) reported relatively higher P in swine lagoon wastewater (61 mg L1). According to De Lange et al. (2001), less utilization of P by swines, overfeeding, and feeder management can result in high P in the manure wastewater. The higher P concentration in dairy (30 mg L1) and poultry (34 mg L1) lagoon wastewater (Bradford et al., 2008) than the current study highlights the variability in different wastewater types due to different sources. The relatively high P in our wastewater suggests that packinghouse wastewater needs to be treated to remove P before it can be permitted to be discharged in surface water bodies as the proposed EPA water quality total P limit is 0.74 mg L1 for Tampa Bay streams (EPA, 2010).

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33 Other elements i.e. Ca, Mg, K, Fe, and Zn showe d marginal increases in wastewater than municipal water (Table 2 1 and Table 2 4) and do not represent constraints on wastewater reuse. Concentrations of Ca in our wastewater was similar to swine lagoon wastewater (51 mg L1) but much greater than municipa l wastewater (4 mg L1) (Biggs and Jiang, 2009; Szogi and Vanotti, 2009). The K concentration in wastewater was lower than the concentration reported in swine (614 mg L1), dairy (178 mg L1) and poultry (1244 mg L1) lagoon wastewater (Bradford et al., 2008; Szogi and Vanotti, 2009). Concentration of Zn was lower than in animal manure wastewater (0.4 1To comply with the surface water discharge standards for P and Cu, wastewater needs to be treated with chemical amendments (alum, ferric chloride, lime) to remove P and Cu from the wastewater (Ebeling et al., 2006; Kang et al., 2003; Wang et al., 2004). Another alternative could be to use the wastewater for land irrigation. For instance, the rate of wastewater at land application sites must not be more than 1.67 cm day ) (Bradford et al., 2008). The tremendous variability in wastewater from different sources suggests the impact of intrinsic and extrinsic sources in elevating concentrations of different constituents. 1 or 167, 000 L ha1 day1Summary above which, wastewater can cause soil toxicity to cover crops such as grasses (FDEP, 2009). A minimum unsaturated depth of 45 cm to the water table has also been recommended to avoid ponding at the surface and maintain aerobic conditions in the root zone area of cover crop. The primary concern for establishing all these guidelines was to prevent the degradation of groundwater and surface water quality from the wastewater land application. The primary objective of this study was to characterize the quality of wastewater produced in tomato packinghouses. To achieve our objective, wastewater samples were collected at 30 min interval from two packinghouses in four sampling events. The obtained data suggested

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34 that EC and chloride were elevated in the wastewater because of the use of chlorine based sanitizers in the dump tanks and may pose moderate to strict restrictions for their use as irrigation water in crops like beans, carrot, okra, onion, and strawberry (Haman, 2009). The concentrations of wastewater const ituents were relatively higher in PKG 1 than PKG 2, which were mainly due to the relatively more contact time of tomatoes with dump tank water in PKG 1. Among all elements, P was above the threshold limit of 0.74 mg L1 for surface water discharge in Tampa Bay watersheds and Cu concentration was above the threshold limit of 0.03 mg L1 for groundwater discharge and 0.5 mg L1 for irrigation water in agriculture (Florida Administrative Weekly, 2006). Concentrations of Fe and Zn were less than the threshold value (1 mg L1 ) of irrigation water suitability in agriculture (Ayers and Westcot, 1989). In our study, washing of tomatoes resulted in increased concentrations of all chemical constituents in the wastewater. This suggests that tomato residues (residues of pesticides, insecticides, and/or foliar applied micronutrients) carried with field harvested tomatoes may be the likely sources of P and Cu in wastewater. These results suggest that wastewater needs to be treated for P and Cu if directly discharged to s urface water bodies as their concentrations were above the critical values.

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35 Table 2 1. Selected chemical properties of municipal water used in the dump tanks in two tomato packinghouses before the cleaning of fiel dharvested tomatoes Packinghouse pH EC Chloride P Cu Zn Ca Mg K Fe dS m 1 mg L 1 1 7.20.2 0.430.1 273 0.270.1 0.010.01 0.130.03 341.5 16 0.5 60.2 0.020.01 2 7.10.1 0.380.1 279 0.210.1 0.010.01 0.110.01 341 150.4 60.4 0.020.01 Meanstandard deviation Table 2 2. Potential sources of P, Cu, Zn, and K in wastewater carried from washed tomatoes Wastewater constituent Source Purpose Application rate (L ha 1 ) Days to harvest P Organo P insecticides a) Dimethoate b) Malathion c) Methadiphos Control insects like aphids, drosophila, mites, earthworms, leaf miners, whiteflies 0.5 1 Fungicides Mono and di K salts of phosphorus acid Powdery mildew, Phytopthora, Pythium species 1 Cu Fungicides Copper hydroxide Anthracnose, early blight, late blight 2.0 1 Micronutrients foliar spray Copper sulfate Cu deficiency in plant tissue (<5 mg kg1) on dry wt. basis 2.3 Zn Fungicides a) Mancozeb b) Ziram Anthracnose, early blight, late blight, grey leaf spot 2.7 5 Micronutrients foliar spray Zinc sulfate Zn deficiency in plant tissue (<25 mg kg1) on dry wt. basis 2.3 K Fungicides a) K bicarbonate b) Mono and di K salts of phosphorus acid Powdery mildew

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36 Table 2 3. Simple and stepwise regression models for predicting concentrations of P, Cu, and Zn in wastewater (mg L1 Wastewater constituent ) with the amount of tomatoes washed (t), wastewater pH, and chloride (Cl) in two tomato packinghouses Packinghouse 1 Packingh ouse 2 Step R P value 2 R P value 2 P 1 2 3 4 0.75 + 0.015 t 8 + 0.23 pH + 0.016 t 0.49 + 0.004 Cl + 0.01 t 5.03 + 0.66 pH + 0.004 Cl + 0.0075 t 0.53 0.54 0.76 0.78 <0.05 NS <0.05 <0.05 0.37 + 0.009 t 3.33 0.42 pH + 0.01 t 0.24 + 0.002 Cl + 0.007 t 3.44 0.5 pH + 0.002 Cl + 0.007 t 0.92 0.94 0.92 0.94 <0.05 <0.05 NS <0.05 Cu 1 2 3 4 0.0008 + 0.0074 t 1.28 + 0.18 pH + 0.007t 0.22 + 0.00006 Cl + 0.006t 2.06 + 0.27 pH + 0.0007 Cl 0.72 0.73 0.76 0.78 <0.05 NS <0.05 <0.05 0.11 + 0.008 t 5.2 + 0.76 pH + 0.007 t 0.11 + 0.003 Cl + 0.005 t 5.0 + 0.71 pH + 0.002 Cl + 0.006 t 0.76 0.82 0.77 0.83 <0.05 <0.05 NS NS Zn 1 2 3 4 0.12 + 0.00054 t 0.08 + 0.029 pH + 0.0006 t 0.12 + 0.00002 Cl + 0.0006 t 0.071 + 0.03 pH 0.00001 Cl + 0.000 6 t 0.75 0.79 0.75 0.79 <0.05 <0.05 NS NS 0.09 + 0.0002 t 0.16 0.01 pH + 0.0002 t 0.1 + 0.0001 Cl + 0.0003 t 0.15 0.01 pH 0.0001 Cl + 0.0003 t 0.33 0.34 0.35 0.36 <0.05 NS NS NS NS: Non significant Table 2 4. Selected chemical properties of wastewater produced in the dump tanks in two tomato packinghouses at the end of packing operations Packinghouse pH EC Chloride P Cu Zn Ca Mg K Fe dS m 1 mg L 1 1 6.60.7 2.80.6 1125419 5.71.7 2.20.7 0.30.1 596 252 4914 0.80.2 2 7.10.4 1.30.2 25586 2.80.3 1.90.8 0.10.1 554 211 242 0.10.1 Mean standard deviation

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37 Figure 2 1. Mean amount of washed tomatoes with time during four sampling events in each of the two tomato packinghouses. Error bars indicate mean standard deviation.

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38 0 50 100 150 200 250 300 350 EC (dS m-1) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Tomatoes washed (Mg) 0 50 100 150 200 250 300 350 Chloride (mg L-1) 0 200 400 600 800 1000 1200 1400 1600 1800 0 50 100 150 200 250 300 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Packinghouse 14) Packinghouse BPackinghouse 2 0 50 100 150 200 250 300 0 200 400 600 800 1000 1200 1400 1600 1800 Figure 2 2. Effect of cumulative amounts of washed tomatoes on wastewater EC and chloride during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May

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39 0 50 100 150 200 250 300 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 50 100 150 200 250 300 0 2 4 6 8 0 50 100 150 200 250 300 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Tomatoes washed (Mg) 0 50 100 150 200 250 300 350 Zn (mg L -1 ) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0 50 100 150 200 250 300 350 P (mg L-1) 0 2 4 6 8 0 50 100 150 200 250 300 350 Cu (mg L -1 ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 Packinghouse 1 Packinghouse 2 0 50 100 150 200 250 300 350 Fe (mg L -1 ) 0.0 0.2 0.4 0.6 0.8 1.0 0 50 100 150 200 250 300 0.0 0.2 0.4 0.6 0.8 1.0 Figure 2 3. Effect of cumulative amounts of washed tomatoes on wastewater P, Cu, Zn, and Fe during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May

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40 Tomatoes washed (Mg) 0 50 100 150 200 250 300 350 K (mg L-1) 0 10 20 30 40 50 60 70 0 50 100 150 200 250 300 350 Ca (mg L-1) 30 35 40 45 50 55 60 65 70 0 50 100 150 200 250 300 350 Mg (mg L-1) 14 16 18 20 22 24 26 28 0 50 100 150 200 250 300 30 35 40 45 50 55 60 65 70 0 50 100 150 200 250 300 14 16 18 20 22 24 26 28 0 50 100 150 200 250 300 0 10 20 30 40 50 60 70 Packinghouse 1 Packinghouse 2 Figure 2 4. Effect of cumulative amounts of washed tomatoes on wastewater Ca, Mg, and K during four sampling events (labeled as S 1, S 2, S 3, and S 4) in May

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41 CHAPTER 3 LEACHING OF PHOSPHOR US AND CATIONS IN A SANDY SOIL IRRIGATED WIT H PACKINGHOUSE WASTEWATER Introduction Land application of agricultural and industrial waste products is the most common practice to recycle solid and liquid wastes and improve physical and chemical properties of soils (Debosz et al., 2002; Shiralipour et al., 1992). Although the commercial fertilizers are the major sources of crop nutrients in the US and elsewhere, residual byproducts such as manures, biosolids, composts, and animal and industrial wastewater effluents are routinely land applied (VanWiering en et al., 2005). The application of these residuals at agronomic rates to the fields that are close to sensitive water bodies or if applied at very high rates ( 1To characterize the leaching of contaminants in a soil and conduct risk asses sment, lysimeter techniques are widely used as they constitute closed loop systems and thus enable control over water and solute percolating through the soil (Bergstrm, 1990; Weihermuller et al., 2007). Different types of lysimeters include porous ceramic cups (Woodard et al., 2007), homogenized packed lysimeters (Zhao et al., 2009), monolith undisturbed lysimeters, and field based drainage systems (Algoazany et al., 2007; Gentry et al., 2007). Porous ceramic cups are easy to install but they may adsorb considerable amounts of elements such as manganese ( Mn ) nickel ( Ni ) and zinc ( Zn ) which may underestimate the concentration of metals in soil solution ) can impair water quality (O'Connor et al., 2005). For instance, many water bodies in the US are phosphorus (P) limited and the main sources of P are point such as wastewater discharge and nonpoint sources such as leaching and runoff from landscape (Jensen et al., 1999). Since many of the Florida soils are coarse textured, have low org anic matter and limestone fractures, the vertical movement (or leaching) of P to the groundwater is the main concern (Elliott et al., 2002; Reed et al., 2006; Yang et al., 2007).

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42 (Wenzel et al., 1997). In addition, porous cups have been speculated to have an inherent bias in preferen tially monitoring the chemical composition of macropores at the expense of micropores (Weihermuller et al., 2007). Similarly, the use of field drainage systems can be problematic due to lack of control over the environmental conditions such as temperature and humidity at the installation site. Monolith lysimeters which provide a well defined boundary with one dimension vertical flow are widely accepted for accurate determination of solute transport in undisturbed soils (Chardon et al., 2007; Jabro et al., 2001; Jensen, 1994; Malone et al., 2004). As most of the soils in Florida are coarse textured and lack soil structure, which will make it nearly impossible to obtain intact soil columns, the use of soil lysimeters with homogenized packing can be a good appr oach for conducting the leaching studies. In addition, wastewater contaminant losses via preferential flow can be avoided in homogeneous soil conditions because of the uniform packing which can otherwise occur in structured monolith lysimeters via macropo res (Gjettermann et al., 2009; Malone et al., 2004). Long term land application of liquid waste has been shown to increase the soil P levels (Johnson et al., 2004), therefore, in order to be sustainable, these practices must consider the fate and transport of P to groundwater. As liquid wastes contain a diverse mix of various metals that may either leach from or be retained in the soil structure by chemical reactions or can be taken up by plants depending upon the soil type, wastewater properties, and irrigation amounts. For instance, Barton et al. (2005) reported that 2year application of domestic wastewater containing 5.8 mg total P L1 in intact clay loam lysimeters (0.46 m wide and 0.7 m deep) resulted in 16% leaching of the applied P. They attributed higher P leaching in the clay loam soil to low P uptake by plants. Similarly, Zvomuya et al. (2005) observed that the application of potato processing wastewater (3.6 mg L1 total P) in intact sandy loam lysimeters (0.3 m wide and 1.5 m long)

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43 resulted in re latively high leachate concentration of P (3.5 1Soil properties are also known to determine the P leaching potential in a soil. T herefore, the knowledge about the reaction of P with soil components can provide insights about the likelihood of P leaching. For instance, Toor et al. (2005a ) reported that application of dairy wastewater (36 mg total P L ) suggesting that some of the P in leachate was released from soil reserves in addition to the wastewater applied P. 1) in undisturbed silt loam lysimeters (0.5 m wide and 0.7 m long) resulted in 31), where 95 applied P was adsorbed by soil colloids such as iron (Fe) and aluminum (Al). Mamo et al. (2005) applied potato processing wa stewater of low (1.1 mg L1) and high (21 mg L1) total P concentrations in sandy loam lysimeters (0.16 m wide and 0.4 m long). They observed that in low P wastewater treatment, soil acted as a source of P as up to 345% of applied P was recovered in leachate while in high P wastewater treatment, soil acted as a sink as only 38% of applied P was recovered in leachate. Woodard et al. (2007) applied dairy wastewater at 70 ha1 per application in packed sandy soil lysimeters (0.05 m wide and 1.5 m long) and reported low P concentration ( 0.08 mg L1) in the leachate due to P retention by calcium (Ca) and Al added with wastewater in soil. Thus, the chemical characteristics of wastewater can play an important role in determining the net losses of a constituent from a soil system. According to Chen et al. (2003), soil Mn oxides, organic matter, and calcium carbonate ( CaCO3) can also fix P in a soil. Thus, the secondary nutrients such as Ca and magnesium ( Mg ) present either in the soil or added with the wastewater can affect the movement of P in the soil. Apart from P, cations such as Ca, Mg, and sodium ( Na ) were reported to leach in undisturbed silty loam lysimeters (0.6 m wide and 1.2 m long) following the application of meat processing wastewater (26 mg L1 Ca, 255 mg L1 Na, and 7 mg L1 Mg) with leachate concentrations of 3 1, 201,

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44 and < 5 mg L1Lastly, the climatic factors can play an important role in determining the extent of P leaching in a soil. For example, Florida receives about 135 cm rainfall each year, which may enhance the leaching of P in the sandy soils. Thus, wastewater, soil, and rainfall conditions in Florida highlight the concern of P l eaching in soils amended with tomato packinghouse wastewater as 54% of the packinghouse wastewater is disposed in agricultural lands (Florida Tomato Committee, 2007). To the best of our knowledge, no information is available about the effect of packinghous e wastewater on the transport and/or retention of P and cations such as Ca, Mg, and Na when applied in coarse textured soils. Thus, our objective in this study was to evaluate potential leaching of P and cations in a typical Florida sandy soil amended with packinghouse wastewater. The information thus obtained, can be used to assess the feasibility and fine tune the land application of wastewater to reduce leaching losses of P and prevent groundwater contamination in Florida. respectively (Magesan et al., 1999). They attributed the leaching behavior of cations to the preferential flow in soil and removal of cati ons in soil that were applied with past irrigations. These studies have shown that the wastewater characteristics such as concentration of P, Ca, and Al (Mamo et al., 2005; Woodard et al., 2007) as well as soil characteristics such as texture, contents of P, and soil minerals such as Fe and Al oxides in soil (Toth et al., 2006; Zvomuya et al., 2005) along with uptake of P by plants (Barton et al., 2005) control the movement of P in the soil profile. Materials and Methods Study Si te and Sample Collection Soil used in column study was obtained from the Gulf Coast Research and Education Center, University of Florida in Wimauma, FL (Latitude: 270 45 44.13 N; Longitude: 820 13 20.36 W). The soil at the site is somewhat poorly drained (seasonal water table 60 to 106 cm)

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45 and the depth to the restrictive layer (Bh horizon) is more than 200 cm (USDA NRCS, 2009b). The soil at the site was zolfo fine sand series (sandy siliceous, hyperthermic oxyaquic alorthods) which is the second most dominant series (7% of total area) in the study area (Hillsborough County) after Myakka series (USDA NRCS, 2009a). In the past, the site was under citrus cultivation while for last 10 years, the site was not under cultivation. Soil samples were collected from two distinct horizons: 1) Ap: disturbed surface soil horizon ranging from 0 to 17 cm, and 2) A/E: transition subsurface horizon ranging from 17 to 50 cm. The collected soil samples were separately air dried for about 1 using a 2mm sieve (US sieve No. 10). A subsample was taken from each of the two horizons and was retained to determine physical and chemical properties of soils. Column Preparation, Setup, and Equilibration Soil columns were built by cutting a 30 cm internal diameter polyvinyl chloride ( PVC ) pipe into 50cm long section (total surface area: 730 cm2) using a modification of the methodology developed by Maguire and Sims (2002) to study P leaching in soils. In each PVC column, about 45 kg of air dried and s ieved soil from A/E horizon was packed in lower 17 cm of soil columns to achieve the measured field bulk density of 1.87 g cm3. About 23 kg of soil from A horizon was packed in top 0 density of 1.77 g cm3Each column had an end cap at the bottom (Figure 31). To prevent sand loss in leachate with irrigation, a section of th e cheesecloth was placed at the bottom of each end cap. The end To achieve these field bulk densities, packing of both horizons was done in 5cm increment depth as suggested by other researchers (Ashworth et al., 2008; Funderburg et al., 1979; Gao and Trout, 2006; Mamo et al., 2005; Park et al., 2002). Afte r each 5 cm increment addition in the column, soil was tapped for 3 increment of soil.

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46 cap was then packed up to 5cm depth with a mixture of washed sand and gravels. After packing, each end cap was securely attached to the bottom of PVC column and sealed with a sealant to prevent water leakage, if any. A hole was drilled at the center of the end cap to which a plastic pipe was attached to collect leachate in 2 L amber glass bottles. All the packed soil columns were placed in the greenhouse at controlled temperature of 30 0The soil columns were equilibrated by first wetting the soil with de ionized water equivalent to about 1 pore volume (PV) of soil (15 cm water depth or 11.1 L in each column) to remove any air bubbles, if entrapped, during the packing of soil columns and to ensure homogeneous moisture in all columns for subsequent experiments. Soil columns were left to freely drain for a few days and then were wetted by adding deionize d water equivalent to a total of 0.8 PV (11.69 cm water depth) in 1.67 cm per day increments for 7 days. The wetting events were continued (three events) till coefficient of variation in leachate volume was <10% in all the columns so as to ensure uniform h ydrologic flow in all columns (Table 3 1) The rationale for using 1.67 cm per day as application was that it corresponded to about 0.2 PV of soil columns and hence prevented any ponding on the soil columns. C (F igure 3 1) to ensure similar experimental conditions for the duration of the experiment. Treatments and Leachate Collection In the greenhouse, 12 packed soil columns were arranged, in triplicates, for control and three application rates (Low, Medium, and High) of wastewater treatments (Table 3 2). Control treatment received deionized water while the medium treatment received packinghouse wa stewater, both at the rate of 1.67 cm per day. Other two treatments received wastewater application at low (0.87 cm per day) and high rates (2.5 cm per day). This was done to determine the likely impacts of adding wastewater below and above the medium appl ication rate (1.67 cm per day). All soil columns were continuously irrigated for about 10 min once a day using the

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47 watering can. The wastewater used in the study was collected from one of the packinghouse. The collected wastewater (400 L at end of the pack ing operation) was filtered through a cheesecloth to remove leaves and debris and was stored at 40A total of 30 leaching events were conducted based on daily application of wastewater in the soil columns during August September 2009. The rationale for conducting daily leaching events for 30 days was to be consistent with the field practice as packinghouse wastewater supply and use is seasonal (typically 46 weeks two times a year). The application of wastewater for 30 days resulted in addition of about 5 PV of irrigation water in high wastewater treatment. While the control and medium wastewater treatments received 3.3 PV and low wastewater treatment received 1.6 PV during 30 day period. Leachate was collected after 24h of equilibration, leachate volume was measured, and a subsample was taken for analysis. C till use in the leaching experiment. Soil and Water Analysis Soil samples from both horizons were analyzed for sand, silt, and clay using hydrometer method (Day, 1965). Field bulk density of undisturbed soil cores was determined as described in Blake and Hartge (1986) by collecting samples at 5cm depth intervals be ginning from 0 to 50 cm. Particle density of soil horizons was measured using Pycnometer method of Blake and Hartge (1986). Using the bulk density and particle density of soil samples, porosity of each soil horizon was calculated according to following equation. 100 density Particle density Bulk 1 (%) Porosity Soil pH was measured by equilibrating 10 g of soil with 20mL of de ionized water (1:2) for 1 h with a digital meter (Accumet XL60, Dual channel pH/ion/conductivity/dissolved oxygen meter, Fisher Scientific, Pandan Crescent, Singapore). The electrical cond uctivity ( EC ) of soil samples was measured using a soil to de ionized water suspension (1:1) with the same

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48 digital meter. Total soil organic matter was determined by the oxidation method of Walkley and Black (1934). Total P and 6 cations including Al, Ca, Fe, potassium ( K ) Mg, and Na were extracted from soils, in triplicates, using HNO3 and H2O2Wastewater and leachate pH and EC were measured by using above digital meter. Chloride in wastewater and leachate was determined using a discrete analyzer (AQ2+, Seal Analytical Inc, Mequon, WI). Phosphorus and cations (Al, Ca, K, Mg, and Na) in all wastewater and leachate were analyzed using above ICP OES. The ionic strength of wastewater was calculated using th e Marion and Babcock (1976) ionic strength equation. (USEPA method 3050, 1996) followed by analysis on inductively coupled plasma optical emission spectroscopy (ICP OES) (PerkinElmer Optima 2100 DV; PerkinElmer, Shel ton, CT). Water extractable P and detectable 6 cations (Al, Ca, Fe, K, Mg, and Na) were measured by extracting 4 g of air dried soil with 40 mL of de ionized water (1:10 soil to water ratio) in a reciprocating shaker for 2 h followed by centrifugation at 4 000 rpm for 20min. The solution was then filtered through 0.45m membrane filter paper and filtrate was analyzed for P and 6 cations by ICP OES. EC) Log 009 1 ( 841 1 e I Log Where: Ie = Ionic strength (moles L1EC = Electrical conductivity (dS m ) 1Statistical Analysis ) Basic statistics including mean, standard deviation, range, and coefficient of variation of parameters in leachate samples were performed in Microsoft Excel 2007. Mean concentration (mg L1) of each element was mult iplied with leachate volume to calculate loads. Significant differences in concentrations and loads among control and three wastewater treatments were

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49 determined using least significant difference (LSD) method at P <0.05 using PROC GLM procedure in SAS statistical analysis (SAS Institute, 2007). Results and Discussion Physical and Chemical Properties of Soils Soil in our s tudy was sandy in nature (>92% sand) with very low clay content (<0.4%) (Table 3 3). Surface horizon had lower bulk density and particle density than subsurface horizon while porosity was similar in both horizons (28 gher pH, EC, and organic matter than the subsurface soil (Table 34). Among metals, surface soil had significantly higher total Ca, Mg, K, and P contents than the subsurface soil while Na and Fe did not vary significantly in two horizons. In contrast, tota l Al was lower in surface soil (1284 mg kg1) than subsurface soil (1701 mg kg1Chemical Characteristics of Packinghouse Wastewater Applied to Soil Columns ). Water extraction recovery of different elements varied in two horizons, with greater recovery of Mg and K in surface (17 (14 Na were more water extractable in subsurface (20 (9 5). Phosphorus was more water extractable (8% of total P) in sub surface than surface soil (4% of total P) indicating that labile P may have moved from the surface layer du e to sandy nature of soil. Mean pH of the wastewater applied to soil columns was 6.2 which was lower than other types of wastewater such as potato processing plant wastewater (7. 4) (Zvomuya et al., 2005), dairy manure wastewater (7.0) (Harris et al., 2008), and municipal wastewater (7.2) (Woertz et al., 2009). The EC in the wastewater ranged from 1.94 to 2.44 dS m1 with a mean value of 2.16 dS m1 (Table 3 6). High EC in our wast ewater was due to high chloride which ranged from 551 to 638 mg L1. Total P concentration in packinghouse wastewater ranged from 4 to 4.4 mg L1, which was slightly higher than the potato processing wastewater (3.6 mg L1) (Zvomuya et al.,

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50 2005) while muc h lower than domestic wastewater (>10 mg L1) (Vaillant et al., 2004) and dairy wastewater (28 mg L1Among cations, wastewater was rich in Na (349 ) (Harris et al., 2008). 1) followed by Ca (45 L1), K (32 1), and Mg (21 1). In dairy wastewater, Harris et al. (2008) observed higher concentrations of Ca, Mg, and K (138, 64, and 248 mg L1, respectively) but lower Na (75 mg L1) than our packinghouse wastewater. Similarly, in paper mill wastewater, higher values of Na (422 mg L1) and Ca (108 mg L1Leachate Volume in Soil Columns ) than our wastewater were observed by Howe and Wagner (1996). After 30 leaching events, significant differences in mean leachate depth (cm day1) were observed in all treatments (Table 3 7). For insta nce, wastewater input was greatest in high (2.51 cm day1) resulting in a greater drainage depth of 2.31 cm day1 (92% of applied water) followed by medium and control (1.45 1 or 881Leachate to irrigation (LI) ratios in all treatments was <1 during 30 leaching ev ents indicating that a part of the applied water was always stored in the soil columns (Figure 3 2A). The first eight leaching events showed a continuous and gradual increase in LI ratios from 0.70 to >0.85 in all treatments. Kleinman et al. (2005) observe d that initial leaching events play a significant role in the emergence and development of water flow paths in the soil and continuous irrigation events can lead to apparent steady state flow in soil columns. In subsequent leaching events, LI ratio was 0.86 The LI ratio increased simultaneously at the end of the experiment and was 0.94 in high, 0.88 or 79%) treatments. Wastewater tr eatments exhibited variability in daily leachate volume with more volume recovered in high followed by medium and low treatments due to variable amount of water application.

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51 treatments. Due to the application of variable rates of irrigation water, high treatme nt leached a total of 4.3 PV of water followed by control and medium (2.9 32B). Chloride Breakthrough in Wastewater Amended Soil Columns Chloride anion is a nonreactive tracer and thus, indicates the flow of water in the soil via chloride breakthrough curves. In our study, the curves had sigmoid (S) shape in all treatments (Figure 3 2C), indicating that chloride and water flows were similar throughout the system in spite of the different application rates of wastewater. Th e relative chloride concentration ratio (C/Co) of 0.5 in the curve corresponds to about 1 PV of leachate in three treatments indicating that there was no preferential flow in the soil. This can be due to the homogeneous packing of soil columns with sandy s oil that is typical of Florida. For the chloride breakthrough, at about 1 PV, 50% (i.e. C/Co = 0.5) of the applied chloride appea red in the leachate (Figure 3 2C ), which was an indicator of the uniform convective transport or lack of preferential transpor t in our study (Mamo et al., 2005). According to Mamo et al. (2005), if preferential flow had occurred, chloride would have appeared earlier and also at a high concentration or close to the wastewater concentration. However, this was not the case in our st udy where solute transport occurred through soil matrix only. The graph is divided in three phases based on the nature of leachate. For instance, in phase 1, the leachate during first 0.7 PV in all soil columns was the pre event water (de ionized water) af ter being displaced by applied wastewater. Thus, leachate had very low C/Co chloride ratio. In phase 2 (0.7 event water in the leachate and showed convective solute transport in the system. As a result C/Co ratio gradually increased in all treatments. The breakthrough (increase in C/Co ratio) was observed first in high application rate followed by low and medium application rate. The early breakthrough in low

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52 application rate than medium rate suggested that soil was not completely saturated in low application rate. Camo breco et al. (1996) reported similar results with chloride breakthrough in the homogenized soil columns where breakthrough was observed after 0.5 and the ratio continue d to increase till it reached unity (1) indicating soil matrix flow in their soil profile. In phase 3 (after 1.1 PV), there was only wastewater flow in the leachate. The C/Co ratio did not show any significant increase and ranged from 0.7 to 1 indicating t he steady state flow of wastewater. In general, breakthrough curves obtained in our study were typical of the homogeneous soil media indicating the flow from soil matrix only (Camobreco et al., 1996). During the study period, leachate chloride showed maxim um concentration of 6191 in three application rates. These concentrations were greater than the groundwater cleanup target level of 250 mg L1 Leachate pH and EC in Control and Wastewater Amended Soil Columns (Florida Administrative Code, 2010; Florida Administrative Weekly, 2006) suggesting that wastewater app lication can increase concentration of chloride in the groundwater. Mean pH of 30 leaching events was greater in control and low (6.87 and high treatments (6.44 (Table 3 8). Leachate pH was significantly greater ( P <0.05) in control (6.9) and medium (6.5) treatments suggesting that wastewater application at medium rate (1.67 cm day1) decreased the leachate pH which can be attributed to the acidic nature of wastewater. Increasing the wastewater application rate above medium to high did not significantly decrease the pH (6.4). During 30 leaching events, leachate pH was about neutral (6.7 from 6.6 to 7.1 in phase 1 (<0.7 PV) which was the pH of pre event water (Figure 3 3). In phase 2 of mixture of wastewater and preevent water, leachate pH declined gradually and approached close to the wastewater pH of 6.2 in high treatment. For instance in medium and high treatments, pH

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53 decreased from 6.7 to 6.2 during 0.7 high treatment as there was only wastewater flow. Application of wastewater in soil columns significantly increased the leach ate EC ( P <0.05) (Table 38). For instance, EC in medium treatment was 13 times (1.59 dS m1) greater than control (0.12 dS m1). More wastewater application in hightreatment resulted in additional 11% increase in leachate EC (1.78 dS m1) than the medium treatment. In contrast, EC was 46% lower in low treatment (0.85 dS m1) that received half of the wastewater than medium treatment. In control treatment, EC was <0.1 dS m1 during 30 leaching events while in wastewater treatments, EC ranged from 0.1 to 0.3 dS m1 in the phase 1 (<0.7 PVs) as this was the pre event de ionized water in the leachate (Figure 3 3). The application of wastewater (high EC) in soil columns continued to displace the pre event water (low EC) from soil profile that resulted in increas ing EC in phase 2 (0.71.4 PV) from 0.1 to 2.5 dS m1. In phase 3 (>1.4 PV), leachate EC values were similar to EC of applied wastewater (1.9 2.4 dS m1Transport of P, Na, Ca, Mg, and K in Soi l Columns ) suggesting that equilibrium was achieved in the soil columns. During 30 leaching events, leachate P concentration increased gradually from 0.38 to 0.96 mg L1 in control while in wastewater treatments, P concentration increased (0.2 to ~ 0.8 mg L1) only in phase 1 (0.5 4) as this was the pre event water displaced by addition of wastewater. The deionized water used in control treatment and in pre wetting events desorbed P from the soil continuously and thus soil acted as a source of P in the leachate. Since subsurface soils had relatively high water soluble P (1214 mg L1), the application of de ionized water having very low ionic strength resulted in increased leaching of P from the subsurface soil while in wastewater ( high ionic strength) treated soils, P was strongly adsorbed in the soil. According to He et al. (1997), the adsorption of P increases with the increase in ionic strength at

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54 high pH of solution while at low pH, the adsorption of P was decreased with increase in ionic strength. The soil packed in soil columns had 1214 mg L1 water extractable P at soil to water ratio of 1:10 (Table 3 5) and thus P recovered in leachate resulted from interaction of de ionized water with soil. During phase 2 and 3 (>1 PV), leachate P decreased to 0.21 in wastewater treatments. The medium treatment that received same amount of water as control had P concentrations between 0.2 and 0.4 mg L1 during 30 leaching events. In high treatment, leachate P increased from 0.4 to 0.6 mg L1In our study, when additional P (4.2 mg L till 1.9 PV and then remained constant for rest of the study period (4.3 PV). 1) was added via wastewater in the soil, P concentration increased in the beginning (0.5 event water which removed a measurable amount of P from the soil called background P concentration and increased leachate P concentration. The decline in P concentration in later stages (till 1.1 PV) coincided with the flow of wastewater in the leachate indicating that a part of the P added via wastewater was fixed and thus soil acted as P sink as wastewater appeared in the leachate. This suggests that our soil can buffer the P added with wastewater (total P: 4.2 mg L1) by adsorbing it in the soil and thus reducing the leachate concentration. Mamo et al. (2005) obtained the similar results when wastewater (21 mg P L1The daily leachate P in all wastewater treatments was much below the wastewater P concentration of 4 mg L ) was added in high P soil, which reduced P leaching. According to Toor et al. (2005b), dissolved P in the solution can quickly adsorb onto soil minerals as it penet rates onto soil aggregates. Therefore, most of the P added with wastewater was not leached but retained in the soil. 1 suggesting that most of the wa stewater applied P was always sorbed in the soil. According to Jensen et al. (1998), high ionic strength of wastewater can increase the P

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55 sorption rates in soil. In a solution like our wastewater which has the variable concentrations and charge of ions suc h as Ca, Mg, Fe, and K, an increase in ionic strength (0.031 mol L1) can increase the net surface charge (surface potential) in the soil (Pardo et al., 1992). As a result, the infiltration of high ionic strength wastewater in soil increased the sorption o f P onto the surface of soil colloids. In addition to wastewater properties, soil native adsorbents such as presence of Fe/Mn and Al oxides, organic matter, and CaCO3 can sorb P in the soil as suggested by Chen et al. (2003). This suggested that high Al (12841), Fe (454 1) and Ca (89 1Leachate concentration of Na was ) in our soil may be the most active adsorption sites of wastewater applied P. 1 in the control treatment (Figure 3 4). Similarly, in wastewater trea tments, leachate Na concentration was low only in phase 1 (0.6 PV) which was the preevent water. This indicated that no water soluble Na was leached from the soil which can be due to low water soluble contents (3 1) of Na in soil as compared t o other dominant cations (Ca, Mg, and K) having water soluble contents of 4 1 (Table 35). This resulted in low Na exchangeable percent age (0.21 most of the Na in soil was in nonexchangeable form. Secondly, the dil ution factor in soil columns was also low as total amount of de ionized water added (36.6 L or 3.3 PV in control) during 30 leaching events was not sufficient to extract water soluble Na from the soil weighing 67 kg of mass (~2:1 soil water ratio). In phas e 2, leachate Na gradually increased to 184 mg L1 at 1.3 PV in low, and 3161 at 2 PV in medium and high treatments. The increase in leachate Na during this period (phase 2) indicates the appearance of a part of wastewater in the leachate along w ith some pre event water. During phase 3 (> 2 PV), Na concentration was constant in wastewater treatments (33520 mg L1) similar to chloride breakthrough curves suggesting that flow of Na rich wastewater in the soil also increased Na concentration in the

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56 leachate. However, leachate concentration of Na was always less than wastewater concentration (358 mg L1Since Ca and Mg are divalent ions, they exhibit similar chemical properties, and as a result show a very similar solute transport behavior in the coarse textured soil. In the control treatment, de io nized water leached small concentrations of Ca (11 ) in all treatments indicating that a part of applied Na was fixed in the soil. This can be attributed to the high sodium adsorption ratio (SAR) of the packinghouse wastewater (10.8) as the higher values of SAR can result in preferential and greater adsorption of Na in the cation exchange sites in soil than other divalent cations such as Ca and Mg (Robbins, 1984). According to Leal et al. (2009), high SA R in water is expected to cause an increase in soil sodium exchangeable percent age enhancing the risk of sodification associated with soil structure degradation. This may also result in water logging and decreased water infiltration. In our study, similar percentage of water recovery in medium and high treatments may result from the reduced infiltration in high treatment due to higher rate of Na application in the soil with wastewater. However, Gloaguen et al. (2007) reported that behavior of Na in the soi l solution depends predominantly on the balance between adsorption and desorption processes at cation exchange complex. In our study, most of the Na applied was adsorbed in the soil at the expense of Ca and Mg desorption from soil exchange complex thus causing an increase in Ca and Mg concentration in leachate. 1), Mg (1.8 1), and K (5.2 to 8.7 mg L1) in leachate (Figure 3 4). Similar concentrations were observed in wastewater treatments during phase 1 (0.5 event water/de ionized water infiltrates in the soil, some of the water soluble Ca, Mg, and K were leached from the soil. As most of the Florida soils have originated from sandy marine deposits and limestone minerals (Watts and Collins, 2008) such as calcite (CaCO3), and dolomite [CaMg(CO3)2], soils

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57 in our study are expected to have sufficient amounts of these minerals. In addition, application of gypsum (CaSO4) is a common practice in Florida to buffer the soil pH in acidic soils suggesting that dissolution of these minerals with de ionized water can also release some of these elements. During phase 2 (0.6 and Mg, leachate concentration exceeded the wastewater concentration at 0.8 V and reached to the maximum concentration of 150 1 and 401, respectively at 1.1 either from the soil or past accumulations of applied wastewater. Ho wever, in case of K, leachate concentration reached the maximum concentration of 24 1 at 1.1 PV (12 less than wastewater concentration suggesting that some of the applied K was always fixed in soil. Since K is mainly exchangeable in t wo forms: soil solution K, and exchangeable or available K which is present on the surface of minerals, the desorption of K in our soil was most likely from the K bounded to soil minerals. Because soil profile might have also contained some pre event water some K was available in solution forms. In phase 3 (>1.4 PV), leachate concentrations of cations decreased and became constant in case of Ca and Mg while for K, leachate concentration began to increase after 2.9 PV. Interestingly, Ca concentration was al ways above the wastewater concentration while Mg showed the concentration below wastewater applied Mg after 1.7 accumulation of Mg in soil. According to Miyamoto and Pingitore (1992), continuous addition of Mg in soil may sometimes exceed the solubility product of Mg compounds which results in re adsorption of Mg in the soil similar to our observation. In addition, high Ca:Mg ratio in our soil (7:1) and applied wastewater (2:1) may also result in less retarded flow of Ca as compared to Mg in the soil. Thus, based on our

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58 observations, soil native Ca and Ca from past accumulations of applied wastewater in soil acted as source of Ca in leachate while most of the applied P, Na, K and Mg were retained in soil. Mass Balance of Constituents in Soil Columns In control treatment, where no P was added, about 3 kg ha1N o Na leaching was observed in the control treatment while in wastewater treatments; about 861% of applied Na was leached (Table 3 9). In the control treatment, de ionized water leached about 65 kg ha of P was leached (Table 3 9). However, in low, medium, and high treatments, about 5, 7, and 13% of applied P was leached, respectively suggesting that low irrigation rates gives P sufficient time to react with soil components resulting in more P fixation and less leaching potential as suggested by Mamo et al. (2005). Since no vegetation was grown in the soil columns, remainder (87 95%) of applied P was fixed in the soil profile. 1 of Ca from the soil and about 100 was leached in wastewater treatments suggesting that 10 37% of Ca in leachate was contributed by the soil profile which includes both native soil Ca or past accumulations of applied wastewater. About 12 kg ha1 of Mg was leached in control treatment while in wastewater treatments, about 60 82% of applied Mg were leached in the soil. Similarly, K leached in the soil with leaching potential of 3350% while de ionized water leached about 29 kg of K ha1Mean Concentrations of P, Na, Ca, Mg, and K in Leachate from the so il in the control treatment. Overall, a part of the elements such as P, Na, Mg, and K was fixed in soil while some of the Ca in leachate was contributed from the soil profile. Wastewater application did not have any significant effect on leachate P in control and three wastewater treatments (0.33 1) (Table 3 10). In fact, control had highest mean leachate P (0.7 mg L1) followed by high (0.6 mg L1), medium (0.33 mg L1), and low (0.28 mg L1) treatments. Mean P in the applied wastewater (4 mg L1) was much greater than the leachate

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59 P in wastewater amended treatments ( 1) indicating that most of the P applied with wastewater was retained in the soil. In contrast, increase in rate of w astewater application resulted in a linear increase in Na concentration in leachate. For instance, mean leachate Na was 0.18 mg L1 in control while in wastewater treatments, mean Na was 35, 188, and 235 mg L1 in low, medium, and high treatments, respecti vely (Table 3 10). The highest rate of wastewater application resulted in 25% greater Na while lowest rate of wastewater application resulted in 81% lower Na than medium treatment. The applied wastewater had higher Na concentration (358 mg L1) than the le achate Na (35 1) suggesting that some of the Na was also retained in the soil profile. Leachate collected in wastewater treatments had about 5 times (66 1) greater Ca than the control treatment (15 mg L1). In contrast to P and Na, leachat e Ca in wastewater treatments (66 1) was greater than the applied Ca in wastewater (47 mg L1Implications for Land Application of Packinghouse Wastewater ) suggesting that some of the Ca in leachate originated from soil profile. Concentrations of Mg and K showed a similar behavior in wastewater treatments. U nlike Ca, Mg and K in applied wastewater were greater than leachate from wastewater treatments suggesting that a part of the Mg and K was retained in the soil similar to P and Na. We evaluated t he suitability of packinghouse wastewater as irrigation water for agricultural use following general water quality guidelines of Ayers and Westcot (1989) (Table 3 11). According to these guidelines, pH of packinghouse wastewater was close to the suggested normal range of 6.5 1) and chloride (593 mg L1) in the wastewater may pose slight to moderate restrictions on irrigation use in salt sensitive crops such as strawberry, onions, and beans (Haman, 2009) indicating that careful management is required for the selection of crop and irrigation practices in sites that use packinghouse wastewater as irrigation water. The calculated SAR in the packinghouse wastewater was very high (10.8)

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60 compared to normal value of 3 ere limitations for wastewater use as an irrigation source in the soil causing soil crust formation and/or reduced infiltration. Wastewater application at medium application rate (1.67 cm per day) significantly decreased the pH of leachate than the contro l treatment due to the flow of wastewater that had low pH. Another possible reason for the low pH of solution can be the discharge of hydrogen ions from the soil itself (pH=5.5 wastewater. This mechanism of cation hydrogen exchange was similar to the action of cationic resins (immobile solid particle) which are commonly used in wastewater to remove cations such as Na and Ca from the solution and release hydrogen ions in the solution during ion e xchange (Ion Exchange Resin, 2010; Skogley and Dobermann, 1996). Application of wastewater at medium rate (1.67 cm per day) resulted in increased EC of the leachate. Further increase in application rate to 2.51 cm day1 (high) increased the EC significantl y at P <0.05. Thus, the source of irrigation (wastewater) as well as the application rate of irrigation water (0.87 day1) affected the leachate EC. Since the applied wastewater had relatively high ionic strength (0.031 moles L1) than de ionized wa ter, direct flow of wastewater in the soil columns resulted in high EC in the leachate. The application of wastewater at medium and high treatments significantly increased the mean leachate concentration of cations (Na, Ca, Mg, and K) in the soil than the control while no effect was observed in mean P concentration (Table 310). The maximum concentrations of Na (3451) in leachate were greater than the Florida groundwater cleanup target levels of 160 mg L1 suggesting that high Na in the wastewater can be a concern for the groundwater quality. The Ca, Mg, and K elements in leachate are not of critical concern in Floridas surface waters and groundwater. The current experimental design

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61 did not include plants so the effect of nutrient plant uptake was not taken into account, which may modify the leaching behavior of some elements. Summary Application of packinghouse wastewater at medium rate (1.67 cm day1) in a typical coarse textured soil of Florida did not result in increased P leaching losses sugge sting that packinghouse wastewater can be safely land applied in the soils having similar chemical properties as in our study. The high ionic strength (0.031 moles L1 ) of wastewater resulted in enhanced P adsorption on Al, Fe, and Ca sites in soil. In addition, a part of the applied Mg and K was also retained in the soil. In contrast, wastewater application resulted in removal of Ca from the soil profile which can be either native Ca in soil or past accumulations of wastewater applied Ca. Since most of the P applied with packinghouse wastewater was fixed in the soil resulting in lower P leaching losses, repeated applications of wastewater P may exceed the saturation capacity of soil or saturation of P fixation sites in soil and eventually P leaching. Although the leaching losses of Ca, Mg, Na, and K were elevated in high treatment that received wastewater at 2.51 cm per day, in most of the Florida soils these nutrients are not of critical concern. Thus, from environmental prospective, it makes sense to reuse packinghouse wastewater for land irrigation as this will not result in increased losses of P; in fact, our results show that it reduced P leaching. The presence of high Al, Fe, and Ca in our soil enhanced the adsorption of P. W astewater application in soi l resulted in removal of Ca from the soil profile which can be either native Ca in soil or past accumulations of wastewater applied Ca.

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62 Table 3 1. Pre wetting/pre event irrigation schedule in soil columns using de ionized water during July I rrigation event Application rate Depth of applied water Leachate depth MeanSD Range cm day 1 cm 1 15 (1 PV) 15 (1 PV) 1.35041 (8) 0.70 2 1.67 12 (0.8 PV) 7.260.32 (62) 6.45 3 1.67 12(0.8 PV) 8.870.2 (76) 1.22 4 1.67 12(0.8 PV) 9.650.21 (82) 9.16 PV: Pore volume Values in parenthesis indicate percent recovery of applied water Each of the irrigation events 2, 3, and 4 were conducted continuously for 7 days and leachate was collected on day 8. Table 3 2. Treatments applied in soil columns Treatment Depth of irrigation Type of water cm day 1 Control 1.67 De ionized water Low 0.87 Wastewater Medium 1.67 Wastewater High 2.51 Wastewater Florida Department of Environmental Protection recommended rate of wastewater Table 3 3. Selected physical properties of surface (0 the packed soil columns Parameter Surface Subsurface Sand (g kg 1 9241.3a ) 9350.4a Silt (g kg 1 741.3a ) 610.01a Clay (g kg 1 20.4a ) 40.4a Bulk density (g cm 3 1.770.04b ) 1.870.02a Particle density (g cm 3 2.580.01b ) 2.620.1a Porosity (%) 311.5a 280.9a Meanstandard deviation Values followed by same letters in a row are not significantly different at P <0.05 using Fishers LSD.

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63 Table 3 4. Selected chemical properties of surface (0 the packed soil columns Parameter Surface Subsurface pH 60.08a 5.50.01b EC (dS m 1 0.0653a ) 0.03911b Organic matter (g kg 1 231a ) 81b Elements (mg kg 1 ) Al 128439b 170165a Ca 51715a 891b Fe 45423a 44619a P 2686a 1869b Mg 753a 403b K 5921a 232b Na 156a 101a Meanstandard deviation Values followed by same letters in a row are not significantly different at P <0.05 using Fishers LSD. Table 3 5. Water extractable (soil to water ratio= 1:10) elements (mg kg1 Elements ) in two soil horizons packed in the soil columns Surface (0 Subsurface (17 MeanSD % of total contents MeanSD % of total contents Ca 4620a 9 181a 20 K 161a 27 40.4b 17 Al 132b 1 4314a 3 Mg 121a 17 60.9b 14 P 121a 4 142a 8 Na 40.5a 27 31a 33 Fe 40.6b 1 1 4a 3 Standard deviation Values followed by same letters in a row are not significantly different at P <0.05 using Fishers LSD.

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64 Table 3 6. Selected chemical properties of packinghouse wastewater applied in the soil columns Parameter Wastewater used in current study (August 2009) Wastewater collected during May June 2009 MeanSD Range Range pH 6.20.3 6 6.9 6.6 EC (dS m 1 ) 2.160.23 1.9 2.4 1.3 Chloride (mg L 1 ) 59334 551 638 255 1125 Sodium adsorption ratio 10.80.2 10.6 Elements (mg L 1 Na ) 35810 349 377 92 Ca 472 45 50 55 59 K 330.6 32 34 24 49 Mg 220.7 21 23 21 25 P 4.20.1 4 4.4 2.8 5.7 Al BD BD BD Standard deviation (N=6) For details, see chapter 2 Below detection limits Table 3 7. Mean leachate volume of 30 leaching events in control and wastewater irrigated soil columns Treatment Application rate Mean drainage depth Recovery of applied water cm day 1 % Control 1.67 1.450.03b 88 Low 0.84 0.660.1a 79 Medium 1.67 1.510.01c 91 High 2.51 2.310.01d 92 Meanstandard deviation Values followed by same letters in a column are not significantly different at P <0.05 using Fishers LSD. Table 3 8. Mean pH and EC values in leachate collected from four treatments in 30 leaching events Treatment Leachate pH Leachate EC (dS m 1 ) MeanSD Range MeanSD Range Control 6.910.01b 6.52 7.24 0.120.01a 0.06 0.41 L ow 6.870.01ab 6.21 6.95 0.850.06b 0.1 2.52 M edium 6.530.01a 6.51 7.25 1.590.01c 0.11 2.82 H igh 6.440.04a 6.15 7.01 1.780.02d 0.11 2.81 Standard deviation Values followed by same letter in a column are not significantly different at P <0.05 using Fishers LSD.

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65 Table 3 9. Total amounts of P and cations (Na, Ca, Mg, and K) applied in the soil columns, amounts, and percent leaching of applied amounts in four treatments in 30 leaching events Treatment P Na Ca Mg K Amounts applied (kg ha 1 ) Control 0 0 0 0 0 Low 11 898 119 55 82 Medium 21 1796 238 109 165 High 32 2708 359 165 248 Amounts leached (kg ha 1 ) Control 3.01.4ab 0.790.3a 655a 121a 294a Low 0.560.2a 7017b 1308b 331b 273a Medium 1.51.1ba 866 6c 3264c 895c 645b High 4.160.4c 165823d 46310d 1147d 1254c LSD 1.75 27.17 13.29 8.42 7.55 Percent leached Low 5 8 110 60 33 Medium 7.2 48 137 82 39 High 13 61 128 69 50 Meanstandard deviation Least significant difference at P <0.05 Values followed by same letter in a column are not significantly different at P < 0.05 using Fishers LSD. Table 3 10. Mean leachate concentrations (mg L1 Treatment ) of P and cations in four treatments after 30 leaching events P Na Ca Mg K mg L 1 Control 0.70.3a 0.180.1a 151.3a 2.70.2a 71a Low 0.280.1a 358b 664b 170.5b 141.2b Medium 0.330.2a 1882c 711c 19.41.2c 141.1b High 0.60.1a 2352d 662b 161b 180.7c LSD 0.41 7.91 4.83 1.60 1.96 Meanstandard deviation Least significant difference Values followed by same letter in a column are not significantly different at P <0.05 using Fishers LSD.

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66 Table 3 11. Guidelines for interpretation of water quality for irrigation purposes in agriculture (Ayers and Westcot, 1989) Potential irrigation probl ems Degree of restriction on use None Slight to moderate Severe pH Normal range = 6.5 EC (dS m 1 <0.7 ) 0.7 >3 Na (SAR) <3 3 >9 Chloride (mg L 1 <106 ) >106 Fe (mg L 1 ) Sodium adsorption ratio

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67 A B C D Figure 31. Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse: A) cheesecloth fixed at the bottom of an end cap, B) end caps filled with sand and gravels, C) and D) packed soil columns.

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68 Figure 3 2. Leachate volume recovery and chlori de breakthrough in soil columns during 30 leaching events: A) Plot of leachate to irrigation ratio with time, B) Plot of leachate to irrigation ratio with pore volumes, and C) Chloride breakthrough curves showing three phases where C is the leachate concen tration and Co is the irrigation concentration. Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Chloride C/Co 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Leachate to irrigation ratio 0.6 0.7 0.8 0.9 1.0 Time (days) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Leachate to irrigation ratio 0.6 0.7 0.8 0.9 1.0 AB CMixture of pre-event water and wastewater (Phase 2) Equilibrium phase (Phase 3) Pre-event water (Phase 1)

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69 Figure 3 3. Mean leachate pH and EC in soil columns in four treatments during 30 leaching events. Error bars indicate standard error of the mean. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 pH 6.0 6.2 6.4 6.6 6.8 7.0 7.2 7.4 Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 EC (dS m -1 ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 Leachate pH Leachate EC

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70 Figure 3 4. Concentration of P, Na, Ca, Mg, and K in leachate collected in four treatments during 30 leaching events. Error bars indicate standard error of the mean. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 50 100 150 200 250 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 10 20 30 40 50 60 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Concentration (mg L -1 ) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 100 200 300 400 Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 5 10 15 20 25 30 35 Control Low Medium High Phosphorus Sodium Calcium Magnesium Potassium Wastewater conc. (47 mg L-1) Wastewater conc. (22 mg L-1)

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71 CHAPTER 4 LEACHING OF TRACE ME TALS IN A SANDY SOIL IRRIGATED WITH WASTE WATER Introduction Biogeochemical cycling of trace metals amo ng soil, plants, water, and even atmosphere is affected by several factors that are both natural and anthropogenic (Tijani, 2009). Anthropogenic activities such as atmospheric deposition from industrial sites, waste disposal or incineration, urban wastewat er, traffic emission, fertilizer use, and long term applications of wastewater in agricultural lands are known to be the important contributors of elevated concentrations of copper ( Cu ) cadmium ( Cd ) lead ( Pb ) and zinc ( Zn ) in the soils (Koch and Rotard, 2001; McLaughlin et al., 2000). The application of wastewater at agronomic rates can provide essential nutrients for plant growth and reduce pressure on ground and surface water for meeting irrigation needs. However, presence of excess amounts of trace metals in some wastewaters can adversely impact soil and water quality (Bradford et al., 2008). For instance, 50day application of industrial wastewater containing 12 mg Cu L1 in loamy clay paddy fields resulted in 6 times greater accumulation of Cu (101 m g kg1) than the control soil (17 mg kg1) in the surface soil (0 s (Cao and Hu, 2000). Similarly, Nayek et al. (2010) reported that application of metal enriched industria l wastewater ( iron ( Fe ) : 0.8, Cu: 0.73, Manganese ( Mn ) : 0.73, and Zn: 0.7 mg L1) in a surface (0 Cu: 258, 212, 176, and 122 mg kg1, respectively), than the control soil (Fe, Mn, Zn, Cu: 86, 87, 77, 66 mg kg1, respectively ). They noted that the accumulation of metals in the surface soil was strongly correlated with organic matter and cation exchange capacity of soil. Tam and Wong (1996) also observed 7, 3.5, and 3 times greater accumulation of Zn, Mn, and Cu, respectively in packed soil lysimeter (70 cm long and 10 cm wide) irrigated with synthetic wastewater (Mn: 20

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72 mg L1, Zn: 20 mg L1, and Cu: 4 mg L1) than control. This was attributed to high clay content (55%) and high cation exchange capacity (315 meq kg1In contrast, Madrid and Barrientos (1998) observed that application of olive mill wastewater (Cu: 35 mg L ). 1; Zn: 53 mg L1) to packed sandy lysimeters (12 cm long and 4 cm wide) leached about 38% of Cu and 20% of Zn applied with wastewater and attributed this to the solubilization of metals bonded with organic polymers by the flow of wastewater in soil. In a recent study by Tijani (2009), application of domestic wastewater (Cu: 2 g L1; Zn: 2470 g L1) in per forated trays packed with sandy loam soil leached Cu with concentration of 6 1 while Zn was retained in soil with relatively low concentration in leachate (66 g L1Ayers and Westcot (1989) recommended maximum concentration of Cu, Fe, Mn, and Zn in irrigation water of 0.20, 1.0, 0.2, and 2 mg L ) than wastewater input. The retention of Zn in the soil was attributed to attenuat ion, plant uptake, and chelation complexation reactions in soil. Thus, in addition to accumulation, significant leaching of trace metals with applied wastewater may pose a risk of groundwater contamination with these trace metals. The retention and/or leaching behavior of metals applied with wastewater are primarily function of soil properties which includes clay content, organic matter, cation exchange capacity, Fe and Mn oxides, and contents of previously retained metals (Mapanda et al., 2005; Tam and Wong, 1996). 1, respectively. However, in our study, wastewater samples collected from tomato packinghouses exceeded the recomm ended Cu and Mn concentrations for irrigation water (see Chapter 2). As most of the Florida soils are typically coarse textured in nature with shallow groundwater and high rainfall (130 150 cm per year). Therefore, it is possible that land application of w astewater containing these metals may result in groundwater contamination. Ground water is also the drinking water sources for 93% of the

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73 Florida population (FDEP, 2008), so it is important to know the fate and transport of Cu, Zn, Mn, and Fe added with tomato packinghouse wastewater in soils, so as to protect groundwater contamination. Presently, no information is available about the interaction of soil components with the metals present in tomato packinghouse wastewater which can play an important role in dictating leaching and/or mass accumulation of contaminants in the soil profile. The objective of this study was to conduct leaching assessment of Cu, Fe, Mn, and Zn in a typical sandy soil of Florida amended with packinghouse wastewater. Materials and Methods Study Site and Sample Collection Soil used in column study was obtained from the Gulf Coast Research and Education Center, University of Florida in Wimauma, FL (Latitude: 270 45 44.13 N; Longitude: 820 13 20.36 W). The soil at the site is somew hat poorly drained (seasonal water table 60 to 106 cm) and the depth to the restrictive layer (Bh horizon) is more than 200 cm (USDA NRCS, 2009b). The soil at the site was zolfo fine sand series (sandy siliceous, hyperthermic oxyaquic alorthods) which is t he second most dominant series (7% of total area) in the study area (Hillsborough County) after Myakka series (USDA NRCS, 2009a). In the past, the site was under citrus cultivation while for last 10 years, the site was not under cultivation. Soil samples w ere collected from two distinct horizons: 1) Ap: disturbed surface soil horizon ranging from 0 to 17 cm, and 2) A/E: transition subsurface horizon ranging from 17 to 50 cm. The collected soil samples were separately air dried for about 1 anually sieved using a 2 mm sieve (US sieve No. 10). Column Preparation, Setup, and Equilibration Soil columns were built by cutting a 30 cm internal diameter polyvinyl chloride ( PVC ) pipe into 50cm long section (total surface area: 730 cm2) using a modification of the

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74 methodology developed by Maguire and Sims (2002) to study phosphorus ( P ) leaching in soils. In each PVC column, about 45 kg of air dried and sieved soil from A/E horizon was packed in lower 17field bulk density of 1.87 g cm3. About 23 kg of soil from A horizon was packed in top 0 measured field bulk density of 1.77 g cm3Each column had an end cap at the bottom (Figure 41). To prevent sand loss in leachate with irrigation, a section of the cheesecloth was placed at the bottom of each end cap. The end cap was then packed up to 5cm depth with a mixture of washed sand and gravels. After packing, each end cap was securely attached to the bottom of PVC column and sealed with a sealant to prevent water leakage, if any. A hole was drilled at the center of the end cap to which a plastic pipe was attached to collect leachate in 2 L amber glass bottles. All the packed soil columns were placed in the greenhouse at controlled temperature of 30 To achieve these field bulk densities, packing of both horizons was done in 5cm incr ement depth as suggested by other researchers (Ashworth et al., 2008; Funderburg et al., 1979; Gao and Trout, 2006; Mamo et al., 2005; Park et al., 2002). After each 5 cm increment addition in the column, soil was tapped for 3 packing before adding next increment of soil. 0The soil columns were equilibrated by first wetting the soil with de ionized water equivalent to about 1 pore volume (PV) of soil (15 cm water depth or 11.1 L in each column) to remove any air bubbles, if entrapped, during the packing of soil columns and to ensure homogeneous moisture in all columns for subsequent experiments. Soil columns were left to freely drain for few days and then were wetted by adding deionized water equivalent to a total of 0.8 PV (11.69 cm water depth) in 1.67 cm per day increments for 7 days. The wetting events C (Figure 4 1) to ensure similar experimental conditions for the duration of the experiment.

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75 were continued (three events) till coefficient of variation in leachate volume was <10% in all the columns so as to ensure uniform hydrologic flow in all columns (Table 41) The rationale for using 1.67 cm per day as application wa s that it corresponded to about 0.2 PV of soil columns and hence prevented any ponding on the soil columns. Treatments and Leachate Collection In the greenhouse, 12 packed soil columns were arranged, in triplicates, for control and three application rates (Low, Medium, and High) of wastewater treatments (Table 4 2). Control treatment received deionized water while the medium treatment received packinghouse wastewater, both at the rate of 1.67 cm per day. Other two treatments received wastewater application at low (0.87 cm per day) and high rates (2.5 cm per day). This was done to determine the likely impacts of adding wastewater below and above the medium application rate (1.67 cm per day). All soil columns were continuously irrigated for about 10 minutes once a day using the watering can. The wastewater used in the study was collected from one of the packinghouse. The collected wastewater (400 L at end of the packing operation) was filtered through cheesecloth to remove leaves and debris and was stored at 40A total of 30 leaching events were conducted based on daily application of wastewater in the soil columns during August September 2009. The rationale for conducting daily leaching events for 30 days was to be consis tent with the field practice as packinghouse wastewater supply and use is seasonal (typically 46 weeks two times a year). The application of wastewater for 30 days resulted in addition of about 5 PV of irrigation water in high wastewater treatment. While the control and medium wastewater treatments received 3.3 PV and low wastewater treatment received 1.6 PV during 30 day period. Leachate was collected after 24h of equilibration, leachate volume was measured, and a subsample was retained for analysis. C till use in the leaching experiment.

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76 S oil and Water Analysis Soil samples from both horizons were analyzed for sand, silt, and clay using hydrometer method (Day, 1965). Field bulk density of undisturbed soil cores was determined as described in Blake and Hartge (1986) by collecting samples at 5cm depth intervals beginning from 0 to 50 cm. Particle density of soil horizons was measured using Pycnometer method of Blake and Hartge (1986). Using the bulk density and particle density of soil samples, porosity of each soil horizon was calculated according to following equation. 100 density Particle density Bulk 1 (%) Porosity Soil pH was measured by equilibrating 10 g of soil with 20mL of de ionized water (1:2) for 1 h with a digital meter (Accumet XL60, Dual channel pH/ion/conductivity/dissolved oxygen meter, Fisher Scientific, Pandan Crescent, Singapore). The electrical conductivity ( EC ) of soil samples was measured using a soil to de ionized water suspension (1:1) with the same digital meter. Total soil organic matter was determined by the oxidation method of Walkley an d Black (1934) Total trace metals including arsenic (A s ) boron ( B ) Cd, cobalt ( Co ) chromium ( Cr ) Cu, Fe, Mn, molyb denum ( Mo ) nickel ( Ni ) Pb selenium ( Se ), and Zn were extracted from soils, in triplicates, using HNO3 and H2O2 (USEPA method 3050, 1996) followed by analysis on inductively coupled plasma optical emission spectroscopy (ICP OES) (PerkinElmer Optima 2100 DV; PerkinElmer, Shelton, CT). Among 13 trace metals analyzed in soils, only 5 trace metals (Cr, Cu, Fe, Mn, and Zn) were above the method detection limit of 0.02, 0.025, 0.3, 0.05, and 0.02, respectively. Water extractable contents of detectable 5 trace metals (Cr, Cu, Fe, Mn, and Zn) were measured by extracting 4 g of air dried soil with 40mL of de ionized water ( 1:10 soil to water ratio) in a reciprocating shaker for 2 h followed by centrifugation at 4000 rpm for 20min. The solution was then filtered through 0.45m membrane filter paper and filtrate was

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77 analyzed for 5 trace metals by ICP OES. Wastewater and leachate pH and EC were measured by using above digital meter. Chloride in wastewater and leachate was determined using a discrete analyzer (AQ2+, Seal Analytical Inc, Mequon, WI). The 4 trace metals (Cu, Fe, Mn, and Zn) in all wastewater and leachate samples were analyzed using above ICP OES. Statistical Analysis Basic statistics including mean, standard deviation, range, and coefficient of variation of parameters in leachate samples were performed in Microsoft Excel 2007. Mean concentration (mg L1Results and Discussion ) of each element was multiplied with leachate volume to calculate loads. Significant differences in concentrations and loads among control and three wastewater treatments were determined using least significant difference (LSD) method at P <0.05 using PROC GLM proc edure in SAS statistical analysis (SAS Institute, 2007). Physical and Chemical Properties of Soils Soil in our study was sandy in nature (>92% sand) with very low clay content (<0.4%) (Table 4 3). Surface horizon had lower bulk densi ty and particle density than subsurface horizon while porosity was similar in both horizons (28 pH, EC, and organic matter than the subsurface soil. Surface soil had significantly greater total Cu, Zn, Mn, a nd Cr contents than subsurface soil while Fe contents did not vary significantly in two horizons (Table 44). Water extraction recovery for different trace metals varied in two horizons, with higher recovery of Fe, and Cu in subsurface (3 rface soil (<2%) while Zn recovery was similar in both horizons (2.5 total in surface and below detection limit in subsurface soil.

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78 Concentrations of Trace Metals in Packinghouse Wastewater Applied to Soil Columns Me an pH of the wastewater applied to soil columns was 6.2 while EC ranged from 1.94 to 2.44 dS m1, with a mean value of 2.16 dS m1. High EC in our wastewater was due to high chloride which ranged from 551 to 638 mg L1. Concentration of Cu was highest foll owed by Fe, Mn and Zn (Table 4 5). Other trace metals such as B Mo, and Cr had concentration 1. According to irrigation water quality guidelines (Ayers and Westcot, 1989), Fe and Zn in the packinghouse wastewater were below the recommended limit s while Cu (0.66 mg L1) and Mn (0.34 mg L1) were higher than the recommended concentrations of 0.2 and 0.2 mg L1Leachate Volume in Soil Columns in irrigation water, respectively (Table 4 5). After 30 leaching events, significant differences in mean leachate depth (cm day1) were observed in all treatments (Table 4 6). For instance, wastewater input was greatest in high (2.51 cm day1) resulting in a greater drainage depth of 2.31 cm day1 (92% of applied water) followed by medium and control (1.45 cm day1 or 881 or 79%) treatments. Wastewater treatments exhibited variability in daily leachate volume with more volume recovered in high followed by medium and low treatments due to variable amount s of water application. Lea chate to irrigation (LI) ratios in all treatments was <1 during 30 leaching events indicating that a part of the applied water was always stored in the soil columns (Figure 4 2A). The first eight leaching events showed a continuous and gradual increase in LI ratios from 0.70 to >0.85 in all treatments. Kleinman et al. (2005) observed that initial leaching events play a significant role in the emergence and development of water flow paths in the soil and continuous irrigation events can lead to apparent steady state flow in soil columns. In subsequent leaching events, LI ratio was 0.86 The LI ratio increased simultaneously at the end of the experiment and was 0.94 in high, 0.88

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79 treatmen ts. Due to the application of variable rates of irrigation water, high treatment leached a total of 4.3 PV of water followed by control and medium (2.9 42B). Chloride Breakthrough in Wastewater Amended Soil Columns Chloride anion is a nonreactive tracer and thus, indicates the flow of water in the soil via chloride breakthrough curves. In our study, the curves had sigmoid shape (S shape) in all treatments (Figure 4 2C), indicating that chloride and water flows were similar throughout the system in spite of the different application rates of wastewater. The relative chloride concentration ratio (C/Co) of 0.5 in the curve corresponds to about 1 PV of leachate in three treatments indicating that there was no preferential flow in the soil. This can be due to the homogeneous packing of soil columns with sandy soil that is typical of Florida. The graph is divided in three phases based on the nature of leachate. For instance, in phase 1, the leachate during first 0.7 PV in all soil columns was the pre event water (de ionized water) after being displaced by applied wastewater. Thus, leachate had very low C/Co chloride ratio. In phase 2 (0.7 event water in the leachate and showed convective solute transport in the system. As a result, C/Co ratio gradually increased in all treatments. The breakthrough (increase in C/Co ratio) was observed first in high application rate followed by low and medium applic ation rate. The early breakthrough in low application rate than medium rate suggested that soil was not completely saturated in low application rate. Camebreco et al. (1996) reported similar results with chloride breakthrough in the homogenized soil columns where breakthrough was observed after 0.5 and the ratio continued to increase till it reached unity (1) indicating soil matrix flow in their soil profile. In phase 3 (after 1.1 PV), there was only wastewater flow in the leachate. The C /Co ratio did not show any significant increase and ranged from 0.7 to 1 indicating the steady state flow of

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80 wastewater. In general, breakthrough curves obtained in our study were typical of the homogeneous soil media indicating the flow from soil matrix o nly (Camobreco et al., 1996). During the study period, leachate chloride showed maximum concentration of 619 1 in three application rates. However, these concentrations were greater than the groundwater cleanup target level of 250 mg L1Trace Metals Transport in Soil Columns Amended with Packinghouse W astewater (Florida Administrative Code, 2010; Florida Administrative Weekly, 2006) suggesting that amounts of wastewater needs to be carefully applied to avoid the accumulation of chloride in the groundwater. During 30 leaching events, daily leachate Cu concentration varied between 0.15 and 0.22 mg L1 in the control treatment (Figure 4 3). In wastewater treatments, Cu increased from 0.11 to 0.25 mg L1 during first 0.5 event water stored in the soil profile from previous de ionized water applications. This was followed by a decrease in concentration till 0.9). In phase 3 (>0.9 ate Cu beg a n to increas e gradually and approached phase 1 concentrations (~0.25 mg L1) in medium and high treatments. Overall, concentrations of Cu in leachate collected from wastewater amended soil columns were much below (<0.32 mg L1) than the applied wastewater Cu concentration (0.5 0.73 mg L1Concentration of leachate Zn was 0.1 ) suggesting that most of the Cu was retained in the soil. Elliott et al. (1986) reported that Cu was strongly adsorbed in the soil after sludge application that resulted in low leaching losses. 1 in the control while in wastewater treatments, Zn concentration was initially 0.1 1 till 0.7 PV (pre event water) or phase 1 but then gradually increased and exceeded the applied wastewater concentration of 0.16 mg L1 (Figure 4 3). It seems that additional Zn in leachate was due to desorption of Zn from soil in the wastewater treatments. According to Barton and Karathanasis (2003), desorption of Zn in the

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81 soil may result from the formation of soluble metal complexes with organic acids, solvents or chelating agents in soil. Davis and Singh (1995) reported that addition of chlorine can enhance Zn removal from the soil due to oxidization of soil organic matter which can then release Zn complexed with organic matter. Thi s seems to be the case in our study as wastewater was rich in chloride. This suggests that additional Zn in leachate may have originated from Zn desorption from the soil. Interestingly, the low treatment showed highest Zn as well as Fe and Mn concentration s in leachate followed by medium and high treatments. In contrast to increasing concentrations of Cu and Zn during phase 1, Fe and Mn showed a sharp decrease till 0.5 PV, followed by constant concentrations (0.71.1 mg L1) in medium and high treatments a nd an increase in low treatment (Figure 4 3). The removal of Fe and Mn during displacement of pre event water could be due to presence of the reduced forms of Fe (ferrous) and Mn in our low pH soil after saturation with water, which are more mobile than ox idized forms (Lewis, 1995). During 30 leaching events, concentrations of Fe in leachate were greater than the wastewater applied Fe concentrations of 0.20.6 mg L1 indicating that significant amount of Fe was removed from the soil. Concentrations of Mn showed a decreasing trend in all treatments till 0.5 PV followed by an increase in wastewater treatments till 0.8 approached the mean applied wastewater Mn concentrations of 0.34 mg L1. After 1 PV, Mn decreased in leachate suggesting adsorption of Mn on Fe oxides or organic matter in soil profile (Khattack and Page, 1992). According to Sposito (1989), the solubility of Mn in soils is highly sensitive to changes in the soil redox conditions. Under slight to moderate saturated conditions, Mn oxides a re more susceptible to dissolution than Fe oxides and as a result dissolution of Mn oxides precedes Fe. Xiang and Banin (1996) observed that a substantial fraction of the Mn

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82 oxides present in sandy soils was dissolved within 3day following irrigation. We observed increased concentrations of Mn in leachate suggesting these findings. Mean concentrations of Cu in leachate were similar in control and three wastewater treatments (0.190.20 mg L1) while Zn was 2 times greater in wastewater (0.30 0.32 mg L1) t han control (0.13 mg L1) (Table 4 7). No effect of increasing wastewater application rate from low to high was observed for Cu and Zn. However, mean concentrations of Fe and Mn decreased as application rate of wastewater increased from low to high. The fl ow of pre event water from the soil columns to leachate resulted in removal of only one trace metal (Cu) while Fe and Mn leaching was decreased till all preevent was displaced by wastewater. This can be because of the relatively higher fraction of water s oluble Cu (2 (0.23 were 0.30 and 0.86 mg L1, respectively which were below the drinking water limits of 1.3 mg L1 for Cu and 5 m g L1Mass Balances of Trace Metals in Wastewater Amended Soil Columns for Zn (USEPA, 2010). Thus, there is least possibility for these metals to be leached in groundwater and affect its quality. Application of de ionized water removed 0.83 kg Cu ha1 fro m the soil in 30 leaching events in the control treatment (Table 4 8). However, wastewater application in low treatment actually resulted in decreasing leaching loss of Cu (0.4 kg ha1). It may be because the low irrigation amount allowed more interaction of Cu applied in wastewater with soil organic matter and mineral oxides. In the medium treatment, about 0.86 kg ha1 of Cu was leached which was similar to control treatment (0.83 kg ha1). The percentage leaching losses of Cu were 25 27% of applied Cu in wastewater treatments suggesting that the remainder of 73 retained in the soil columns. Lin et al. (2008) reported that in a coarse textured soil, most of the Cu applied with wastewater was adsorbed to Fe oxides, soil organic matter and Mn oxides

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83 present in the soil. Soil organic matter and Fe oxides have been reported to have a high affinity to fix Cu which is due to high surface complexation constants (Dzombak and Morel, 1990). Our soil had high content of Fe in both horizons but soi l organic matter was low in subsurface, therefore organic fraction primarily fulvic acids in surface soil and Fe in both horizons may have retained Cu as suggested by Lin et al. (2008) and Cao and Hu (2000). In the control treatment, about 0.57 kg of Zn ha1 was leached as natural loss with deionized water (Table 4 8). However, as wastewater application rate increased from low to high treatment, leaching amounts of Zn increased from 0.62 to 2.12 kg ha1Among four metals, leaching losses of Fe were highest at 3.6 kg ha These leaching amounts are equivalent to 159185% of applied Zn in wastewater suggesting that additional 5985% of Zn was desorbed from the soil or previous accumulations of wastewater applied Zn. According to Spellman (2008), some metals may be desorbed from the soil with increase in irrigation water sali nity and decrease in redox potential and pH. Thus, the greater loss of Zn in our study with increase in wastewater application can be attributed to high EC and low pH of wastewater. 1 in 30 leaching events in control (Table 48). Leaching loss of Fe increased with increase in application rate of wastewater. However, leaching loss as percentage of applied Fe in wastewater decreased due to high background losses of Fe and retention of applied Fe in soil. Assuming the natural loss of Fe from the soil (3.6 kg ha 1) in control treatment, a net loss of 1.64 kg Fe ha1 in medium treatment (that received same amount of water as control) occurred which is about 74% of applied Fe in wastewater. A similar leaching behavior was observed for Mn (70% of applied Mn leaching in medium treatment). Although the amounts of Mn leached in medium and high treatments were similar (5.24 5.45 kg ha1) at P <0.05, percent age leaching loss of Mn was greater in medium (45%) than high (19%) treatment if we take into account the natural loss of Mn in control

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84 treatment. This suggests that with increase in wastewater application more Mn was retained in the soil profile. Summary A pplication of wastewater at medium rate (1.67 cm per day) only increased concentration of Zn at 50 cm depth while no significant effect was observed on Cu, Fe, and Mn concentrations. Application of wastewater at high rate (2.51 cm per day) significantly increased the concentration of Zn and leaching losses of Zn as well as Cu and Mn. A large percentage of the applied Cu was adsorbed in the soil while Fe and Zn were desorbed from the soil. Since our soils had low clay content, high Fe and organic matter in t he surface soil may be the most important adsorption sites for Cu and Mn. The removal of Fe and Mn from the soil may be due to the enhanced mobility of reduced forms of these metals even in slight to moderate saturation conditions imposed by daily irrigati on. We found that medium rate of wastewater application did not significantly affect mean concentration of Cu in the leachate in 30 leaching events but Zn concentrations were elevated but were much below the drinking water limits of 1.3 mg L1 for Cu and 5 mg L1 for Zn (USEPA, 2010) suggesting a minimum risk of groundwater contamination in areas irrigated with wastewater. It should be noted that these leachate concentrations were measured at 50 cm depth, which will further diminish with increase in soil de pth, thus, there is less possibility of these metals leaching to groundwater. However, concentrations of Fe and Mn in the leachate were above 0.3 mg L1 and 0.05 mg L1, respectively of the National Secondary Drinking Water Regulations non enforceable gui delines. Based on results of our study, we suggest that packinghouse wastewater can be safely applied at 1.67 cm per day in most of the sandy soils in Florida.

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85 Table 4 1. Pre wetting/pre event irrigation schedule in soil columns using de ionized water during July Irrigation event Application rate Depth of applied water Leachate depth MeanSD Range cm day 1 cm 1 15 15 (1 PV) 1.350.41 (8) 0.70 2 1.67 12 (0.8 PV) 7.260.32 (62) 6.45 3 1.67 12 (0.8 PV) 8.870.20 (76) 1.22 4 1.67 12 (0.8 PV) 9.650.21 (82) 9.16 PV: Pore volume Values in parenthesis indicate percent recovery of applied water Each of the irrigation events 2, 3, and 4 were conducted continuously for 7 days and leachate was collected on day 8 Table 4 2. Treatments applied in soil columns Treatment Depth of irrigation Type of water cm day 1 Control 1.67 De ionized water Low 0.87 Wastewater Medium 1.67 Wastewater High 2.51 Wastewater Florida Department of Environmental Protectionrecommended rate of wastewater Table 4 3. Selected properties of surface (0 packed soil columns Parameter Surface Subsurface Sand (g kg 1 9241.3a ) 9350.4a Silt (g kg 1 741.3a ) 610.01a Clay (g kg 1 20.4a ) 40.4a Bulk density (g cm 3 1.770.04b ) 1.870.02a Particle density (g cm 3 2.580.01b ) 2.620.1a Porosity (%) 311.5a 280.9a pH 60.08a 5.50.01b EC (dS m 1 0.0653a ) 0.03911b Organic matter (g kg 1 231a ) 81b Meanstandard deviation Values followed by same letters in a row are not significantly different at P <0.05 using Fishers LSD.

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86 Table 4 4. Total and water extractable contents of trace metals (mg kg1 Parameter ) in two soil horizons in the packed soil columns Surface (0 Subsurface (17 Total WE % recovery Total WE % recovery Fe 45423a 40.6b 1 44619a 1 4a 3 Cu 603a 1.20.12a 2 80.4b 0.60.02b 7.5 Zn 276a 0.90.9a 3 41b 0.10.01a 2.5 Mn 262a 0.060.04 0.23 10.05b BD Cr 60.7a 0.050.01a 0.83 20.2b 0.10.02a 5 Meanstandard deviation (N=3); BD: below detection WE: Water extractable Values followed by same letters in a row are not significantly different at P <0.05 using Fishers LSD Table 4 5. Trace metal concentrations of packinghouse wastewater applied in the soil columns Parameter Wastewater used in current study (August 2009) Wastewater collected during May June 2009 Maximum recommended concentration MeanSD Range Range Cu 0.660.07 0.5 1.9 0.2 Fe 0.440.15 0.2 0.2 1 Mn 0.340.11 0.1 0.062 0.2 Zn 0.160.02 0.1 0.1 2 B 0.10.01 0.09 BD 3 Mo 0.090.01 0.1 0.02 0.01 Cr 0.050.01 0.04 0.01 0.1 Standard deviation (N=6); BD: below detection For details, see chapter 2 Ayers and Westcot (1989) Table 4 6. Mean leachate volume of 30 leaching events in control and wastewater irrigated soil columns Treatment Application rate Mean drainage depth Recovery of applied water cm day 1 % Control 1.67 1.450.03b 88 Low 0.84 0.660.1a 79 Medium 1.67 1.510.01c 91 High 2.51 2.310.01d 92 Meanstandard deviation Values followed by same letters in a column are not significantly different at P <0.05 using Fishers LSD.

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87 Table 4 7. Mean leachate concentrations (mg L1 Treatment ) of trace metals in four treatments in 30 leaching events Cu Zn Fe Mn Control 0.190.1a 0.130.1a 0.850.2a 0.120.1a Low 0.20.1a 0.310.09b 1.680.6b 0.480.2b Medium 0.190.02a 0.320.06b 1.170.1ab 0.280.1ab High 0.190.1a 0.30.01b 0.80.2a 0.150.1a LSD 0.06 0.11 0.64 0.21 Meanstandard deviation Values followed by same letter in a column are not significantly different at P <0.05 Least significant difference Table 4 8. Total amounts of trace metals (Cu, Fe, Mn, and Zn) applied in the soil columns, amounts leached, and percent leaching of applied amounts in four treatments in 30 leaching events Treatment Cu Zn Fe Mn Amounts applied (kg ha 1 ) Control 0 0 0 0 Low 1.6 0.39 1.1 0.86 Medium 3.3 0.8 2.2 1.7 High 5.0 1.17 3.3 2.6 Amounts leached (kg ha 1 ) Control 0.830.1b 0.570.2a 3.61ab 0.510.4a Low 0.40.1a 0.620.2a 3.311.1a 0.940.4ab Medium 0.860.1b 1.480.3b 5.240.6ab 1.270.2b High 1.330.3c 2.120.1c 5.451.3b 1.040.1ab LSD 0.32 0.34 1.97 0.53 Percent leached Low 25 159 300 109 Medium 26 185 238 74 High 27 181 163 40 Meanstandard deviation Values with same letter in a column are not significantly different at P <0.05 Least significant difference at P <0.05

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88 A B C D Figure 4 1. Arrangement of soil columns (30 cm wide and 50 cm long) in the greenhouse: A) cheesecloth fixed at the bottom of an end cap, B) end caps filled with sand and gravels, C) and D) packed soil columns.

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89 Figure 4 2. Leachate volume recovery and chloride breakthrough in soil columns during 30 leaching events: A) Plot of leachate to irrigation ratio with time, B) Plot of leachate to irrigation ratio with pore volumes, and C) Chloride breakthrough curves showing three phases where C is the leachate concentration and Co is the irrigation concentration. Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Chloride C/Co 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Leachate to irrigation ratio 0.6 0.7 0.8 0.9 1.0 Time (days) 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 Leachate to irrigation ratio 0.6 0.7 0.8 0.9 1.0 AB CMixture of pre-event water and wastewater (Phase 2) Equilibrium phase (Phase 3) Pre-event water (Phase 1)

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90 Figure 4 3. Mean concentration of trace metals in the leachate in four treatments during 30 leaching events in soil columns. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Concentration (mg L -1 ) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.05 0.10 0.15 0.20 0.25 0.30 0.35 Leachate pore volume 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.2 0.4 0.6 0.8 1.0 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.0 0.2 0.4 0.6 0.8 1.0 Copper Zinc Iron Manganese Wastewater conc. 0.16 mg L -1 Wastewater conc. 0.34 mg L -1 Wastewater conc. 0.44 mg L -1

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91 CHAPTER 5 SUMMARY, CONCLUSIONS, AND REC OMMENDATION Florida is the single largest producer of fresh market tomatoes in US. About 70 tomato packinghouses in Fl orida pack these tomatoes for domestic market and generate 231 million L of wastewater each year. Tomato industry in Florida is facing the dilemma of sustainably managing large amounts of wastewater produced in tomato packinghouses. Because of rapid urbani zation, lack of wastewater disposal sites near packinghouses, and strict Florida surface water discharge regulations, most (54%) of the wastewater generated is disposed in agricultural soils (Florida Tomato Committee, 2007). Since, most of the Florida soil s are coarse textured, have low organic matter and shallow groundwater table, land application of packinghouse wastewater in sandy soils may pose a risk of phosphorus ( P ) and trace metal leaching to the groundwater. Thus, we characterized the wastewater pr oduced during sanitizing operations in tomato packinghouses to identify the elements of concern and evaluated their leaching potential in a typical sandy soil of Florida during land application. Our methodology included collection of wastewater samples at 30min intervals from the dump tanks in two representative tomato packinghouses and analysis of wastewater samples for P and trace metals. Wastewater pH was in the normal range (6.5 packinghouse waste stream (Bartz et al., 2009) while electrical conductivity ( EC ) and chloride were high in our wastewater as compared to Florida surface water discharge guidelines (Florida Administrative Weekly, 2006). The chlorine use for sanitization of tomatoes in the dump tanks resulted in incre ased concentration of chloride in the wastewater and thus EC. About 4.5 times higher chloride were observed in one packinghouse than other while pathogen loads in both packinghouse were similar (Bonilla and Toor, 2010), suggesting that the chlorine use in waste streams needs to be reduced. This will directly benefit packinghouses due to reduced cost of

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92 using chlorine gas while also minimizing chloride and higher EC in the resulting wastewater. The total P concentration in the wastewater was much greater than the proposed numeric total P value of 0.74 mg L1 for the Tampa Bay streams (EPA, 2010), which implies that this wastewater needs to be treated before discharging to surface waters. Among trace metals, copper ( Cu ) concentration in the wastewater was abov e the threshold limit of 0.5 mg L1 for surface water discharge (Florida Administrative Weekly, 2006) while other trace metals such as iron ( Fe ) and zinc ( Zn ) were below the threshold limits of 1 mg L1In our study, we evaluated the leaching potential of P and t race metals such as Cu, Zn Fe, and manganese ( Mn ) in a typical soil of Florida using soil columns. We packed 12 soil columns in two distinct horizons (Ap and A/E) with variable irrigation rates or treatments: (1) control: 1.67 cm per day irrigation, (2) Medium: 1.67 cm per day irrigation, ( 3) High: 2.5 cm pe r day irrigation, and (4) Low: 0.87 cm per day irrigation. The 1.67 cm per day was the application rate suggested by the Florida Department of Environmental Protection for the safe disposal of packinghouse wastewater (FDEP, 2009). All the packed soil colum ns were irrigated for 30 days during August September, 2009 in 4 above treatments and leachate were collected following the If wastewater needs to be surface discharged in those areas where sufficient land is not available for land irrigation, the wastewater can be treated with chemical amendments such as aluminum chloride (alum), ferric chloride, and calcium sulfate (lime), to precipitate P and Cu from the wastewater (Ebeling et al., 2006; Gray, 2005; Kang et al., 2003). The biological nutrient removal is another effective approach to remove P from the wastewater; however as amount of wastewater generated in packinghouse is limited, it may not be a cost effective approach. Thes e recommendations are the potential alternatives that can be used to treat wastewater if surface discharge is the only possible alternative.

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93 daily application of irrigation water. The collected leachate were analyzed for P, calcium ( Ca ) magnesium (M g) potassium ( K ) sodium ( Na ) and trace metals (Cu, Zn, Fe, and Mn) The results indicated that application of wastewater at medium or high rate did not affect mean concentration of P and Cu in the leachate while concentration of Ca, Mg, K, Na, and Zn were elevated in the leachate. The P, Na, K, Cu, and Mn were strongly retained in the soil which can be attributed to multiple factors such as high sodium adsorption ratio (10.8) of wastewater and high aluminum ( Al ) Fe, and Ca and organic matter in soil. In case of Ca, Fe, and Zn, soil acted as source with leaching from either background concentrations and/or past accumulation of these elements from wastewater. The removal of Fe and Mn from the soil may result from the mobility of reduced forms of these metals even in slight t o moderate saturation conditions of daily irrigation. As all of the P and Cu applied with wastewater was fixed in the soil, wastewater application at these irrigation rates does not pose P and trace metal contamination to groundwater although repeated appl ications of wastewater may show detrimental effects with P and Cu exceeding saturation capacity of soil. Thus, from environmental prospective, it makes sense to reuse packinghouse wastewater for land irrigation in Floridas sandy soil.

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94 LIST OF REFERENCES Agricultural Marketing Service. 2008. Tomatoes grown in Florida: increased assessment rate [Online] http://www.floridatomatoes.org/newsite/facts.html (verified March 15, 2009). Algoazany, A.S., P.K. Kalita, G.F. Czapar, and J.K. Mitchell. 2007. Phosphorus transport through subsurface drainage and surface runoff from a flat watershed in east central Illinois, USA. J. Environ. Qual. 36:681693. Ashworth, D.J., F.F. Ernst, and S.R. Yates. 2008. Soil chamber method for determination of drip applied fumigant behavior in bedfurrow agriculture: application to chloropicrin. Environ. Sci. Technol. 42:44344439. Ayers, R.S., and D.W. Westcot. 1989. Water quality for agriculture. FAO Irrigation and Drainage paper 29 Rev .1, Rome. Barton, C.D., and A.D. Karathanasis. 2003. Colloidenhanced desorption of zinc in soil monoliths. Int. J. Environ. Stud. 60:395409. Barton, L., L.A. Schipper, G.F. Barkle, M. McLeod, T.W. Speir, M.D. Taylor, A.C. McGill, A.P. van Schaik, N.B. Fitzgerald, and S.P. Pandey. 2005. Land application of domestic effluent onto four soil types: plant uptake and nutrient leaching. J. Environ. Qual. 34:635643. Bartz, J.A., S.A. Sargent, and M. Mahovic. 2009. Guide to identifying and controlling post harv est tomato diseases in Florida. IF AS/E xtension HS 866, University of Florida. Bergstrm, L. 1990. Use of lysimeters to estimate leaching of pesticides in agricultural soils. Environ. Pollut. 67:325347. Biggs, T.W., and B. Jiang. 2009. Soil salinity and ex changeable cations in a wastewater irrigated area, India. J. Environ. Qual. 38:887896. Blake, G.R., and K.H. Hartge. 1986. Bulk density, In A. Klute, ed. Methods of soil analysis Part I. Physical and mineralogical methods, 2nd ed. American Society of Agro nomy, Madison, WI. Bohner, H.F., and R.L. Bradley. 1991. Corrosivity of chlorine dioxide used as sanitizer in ultrafiltration systems. J. Dairy Sci. 74:3348 3352. Bonilla, J.A., and G. Toor. 2009. Assessment of microbes in tomato packinghouses. Florida tom ato institute proceedings [Online] http://gcrec.ifas.ufl.edu/tropicalpumpkins/tomato%20proceedings%2009.pdf (verified June 15, 2010). Bradford, S.A., E. Segal, W. Zheng, Q. Wang, and S.R. Hutchins. 2008. Reuse of concentrated animal feeding operation w astewater on a gricultural l ands. J. Environ. Qual. 37:S 97115.

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103 BIOGRAPHICAL SKETCH Maninder Kaur Chahal was born in Ferozepur (Punjab), India. The youngest of three children, she spent most of her life in Ferozepur. After her intermediates, she started her bachelors degree in Punjab Agric ultural University, Ludhiana in 2004 and completed in 2008. In June 2008, she started a masters program in the Department of Soil and Water S cience under the supervision of Dr. G. S. Toor at the Gulf Coast Research and Education Center Wimauma, University of Florida. Maninder received her masters degree from the University of Florida in the summer 2010.