Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 54-8
Title: Treatment of citrus processing wastes by activated sludge
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Permanent Link: http://ufdc.ufl.edu/UF00072355/00001
 Material Information
Title: Treatment of citrus processing wastes by activated sludge
Series Title: Citrus Station mimeo report
Physical Description: 3 leaves : ; 28 cm.
Language: English
Creator: Dougherty, Marshall H
McNary, Robert R
Wolford, R. W
Citrus Experiment Station (Lake Alfred, Fla.)
Publisher: Florida Citrus Experiment Station
Place of Publication: Lake Alfred FL
Publication Date: 1954
 Subjects
Subject: Citrus fruit industry -- By-products -- Florida   ( lcsh )
Sewage -- Purification -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaf 3).
Statement of Responsibility: M.H. Dougherty, R.R. McNary and R. W. Wolford.
General Note: Caption title.
 Record Information
Bibliographic ID: UF00072355
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74149980

Full Text


Treatment of Citrus Processing Wastes by Activated Sludge
M. H. Dougherty, R. R. McNary and R. W. Wolford

Considerable time and effort has been spent in the past attempting to
develop a means of treating citrus waste waters that would also give rise to a
useful by-product. Previously methane fermentation or anaerobic digestion has
been studied (3) in which the methane was considered the by-product. It was
found that a preliminary aeration treatment was necessary before an anaerobic
methane fermentation could be carried out. It seemed quite logical therefore to
investigate a strictly aerobic procedure. The activated sludge system appeared to
hold the greatest promise, especially since the sludge itself might be a suitable
by-product. Dried activated sludge from municipal sewage has been used in ferti-
lizers for a number of years. Recently (2) significant amounts of vitamin B12
has been discovered in activated sewage sludge, indicating that sludge from citrus
wastes might also prove to be a good source of this vitamin. Should this prove
to be true, the by-product possibilities would be attractive.

In the beginning this investigation was patterned after that of Sanborn and
Canham (4) of the National Canners' Association. These authors added trisodium
phosphate and sodium nitrate to the raw waste to stimulate biological growth. As
shown in Table 1 nutrients were also added in this work but the amounts were
reduced in succeeding runs until the inorganic additions were eliminated. In
accordance with customary activated sludge procedure, a portion of the sludge
was settled out of the effluent and returned to the primary aeration tank. This
was not done by Sanborn and Canham who were striving to keep the system as simple
as possible.

A report (1) by the Florida State Board of Health covers the results obtained
in a recently completed investigation of citrus waste treatment. This study by
Mr. Ben F. OtNeal included the treatment of citrus processing wastes by activated
sludge. Here also nitrogen and phosphorus in the form of sodium or ammonium
nitrate and superphosphate were added to the raw waste.

In the laboratory investigation reported here the apparatus consisted of a
metal tank which held a supply of feed sufficient for one day (16 liters), three
4-liter aeration tanks, a settling tank and a five-gallon bottle to catch the
effluent. A Sigmamotor pump metered the feed to the first aeration tank from
which gravity flow carried it through the other two aeration tanks in series and
then to the settling tank. Another Sigmamotor pump returned the sludge froi'the
bottom of the settling tank to the first stage of aeration. Thesaludg'e was cir-
bulated in the system:at the rate of'two to three volumes of set ied sludge toi&\
one volume of new feed. The effluent overflowed the top of the :ettlig! tank &
the five-gallon bottle. Each aeration tank received 0.1 cu.ft./min. ofair j
measured through a capillary flowmeter and dispersed through perforated -stainless
steel tubing 5/16 inches in diameter. Several different settling tanks were/used,
but all were primarily of the same design being round with a conicalshaped 'bottom
and equipped with rotating scrapers to move the sludge down to the bottom_ f the
cone where it was picked up by the pump for recirculation. In Runs E, F, G, H
and I (Table 1) an improved settling tank was installed. It was a small replica
of a standard Dorr clarifier having a detention time of approximately 2.5 hr.
This device increased the efficiency of the sludge recirculation to the point where
only small amounts of sludge were lost with the effluent. This caused the sludge
in the system to gradually build up. To maintain satisfactory settling the sludge

Citrus Station Mimeo Report 54-8. Florida Citrus Experiment Station and Florida
Citrus Commission, Lake Alfred, Florida. 470-10/6/53 MHD











TABLE 1


Treatment of citrus processing waste by activated sludge


Laboratory run A B C D E F G H I


Feed
Volume, liters/day
NaPOi added, p.p.m.
NaOa added, p.p.m. nitrogen
Total solids, %
Organic solids, %
Loading, organic solids, lb./cu.ft./day
B.O.D., p.p.m.
Loading, BO..D., lb./cu.ft./day
pH


Effluent
Sludge, % by vol., centrifuged
Total solids, %
Organic solids, %
B.O.D., p.p.m.
pH

Reductions
Organic solids, lb./cu.ft./day
Organic solids, %
B.O.D., lb./cu.ft./day
B.O.D., %


16
o00
130
0.602
0.515
0.428
3090
0.255
5.81

2.0
0.286
0.204
llt35
6.92

0.260
60.8
0.137
53.6


16
500
130
0.326
0.258
0.2134
1700
0.139
7.05

1.1
0.158
0.087
59
8.10


0.141
66.3
0.134
96.5


16
250
65
0.273
0.223
0.184
1630
0.134
6.57

1.0
0.118
0.070
77
7.97


0.125
67.9
0.128
95.3


16
125
32.5
0.271
0.238
0.198
1830
o.154
6.18


2.0
0.142
0.105
181
7..66

0.111
55.9
0.141
91.5


16
0
32.5
0.267
0.242
0.201
2004
0.165
5.52

1.8
0.126
0.102
157
7.52

0.116
57.6
0.151
92.2


16
0
16.5
0.250
0.227
0.189
1754
0.147
5.58


1.3
0.109
0.087
50
7.51

0.116
61.6
0.142
97.1


16
0
0
0.229
01215
0.176
1677
0.137
5.23


0.3
0.071
0.057
52
7.143


0.130
73.7
0.132
96.6


16
0
0
0.258
0.243
0.203
1956
0.163
5.08

0.6
0.083
0.069
82
7.142


0.147
72.1
0.156
95.7


97 8. 0 I I9


10
0
0
0.428
0.o06
0.213
31440
0.179
L.62


0.5
0.098
.079
68
7.58


0.172
80.5
0.175
98.0


Citrus Station Mimeo Report 54-8. Florida Citrus
Lake Alfred, Florida. 470a-10/6/53 MHD


Experiment Station and Florida Citrus Commission,







concentration was not allowed to exceed about 16% (by volume after centrifuging).
Small amounts of sludge were withdrawn from the system each day, otherwise the
sludge volume built up and some sludge spilled over into the effluent in spite of
the improved settling device.

Each run had a duration of from 20 to 30 days. The feed for every run was
made up of canned single-strength orange juice diluted to the desired concentra-
tion with water. The inorganic nutrients, when used, were dissolved in the feed
before it was started through the system. The runs were made successively, re-
circulating the accumulated sludge from previous runs. The culture was developed
from organisms present in the unsterilized equipment, tap water and the air with
no attempt being made to establish special cultures for this work. There is no
doubt that the culture changed with a change in conditions. Before starting to
collect data for Run A the culture had a ropy, slimy appearance with a swampy odor.
During Run A the culture changed to a fine floe and had a yeasty odor. In Runs B
through F the culture had a typical activated sludge appearance and odor. In Run
G the sludge remained similar but changed from a light brown to a dark brown color
which it remained through Runs H and I.

Table 1 gives the data obtained for the various runs* In Run A the reduction
of organic solids and B.O.D. (Biochemical Oxygen Demand) was poor. The concentra-
tion of the feed was apparently too high and overloaded the system. The initial
concentration was lowered in the subsequent runs. In Run C to F the amount of in-
organic nutrients used were gradually reduced and in Runs G, H and I entirely
eliminated without lowering the efficiency of treatment.

The data indicate that very good treatment of citrus wastes can be accom-
plished with the activated sludge process providing the system is not overloaded.
Reduction of organic solids ranged from 55.9 to 80.5% and the range of B.0.D.
reduction in all runs except Run A, where overloading occurred, was 91.5 to 98.0%.

The excess sludge from the system would require further handling. It prob-
ably could be filtered and dried and then used as a fertilizer or added to animal
feed depending upon its composition. Such possibilities are being investigated
at the present time. Also the sludge could, without doubt, be digested anaerobi-
cally to a stable material that could be used to add organic material to our
Florida soils.

Literature Cited

1. Florida State Board of Health. Citrus waste research project final report,
Jan. 1 June 30, 1953. Jacksonville, Florida.

2. Hoover, S. R., Jasewicz, L., Pepinsky, J. B. and Porges, N. Activated sludge
as a source of vitamin B12 for animal feeds. Sewage and Ind. Wastes, 2_4,
38-4 (1952).

3. McNary, R. R., Wolford, R. W. and Patton, V. D. Experimental treatment of
citrus waste water. Food Technol., 319-323 (1951).

4. Private communication.



Citrus Station Mimeo Report 54-8. Florida Citrus Experiment Station and Florida
Citrus Commission, Lake Alfred, Florida. 470b-10/6/53 MHD




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