Sorption of Ammonium Derived from Membrane Treated Landfill Leachate to Woody Biomass

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Sorption of Ammonium Derived from Membrane Treated Landfill Leachate to Woody Biomass
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Lloyd, James B
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Degree:
Master's ( M.S.)
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University of Florida
Degree Disciplines:
Environmental Engineering Sciences
Committee Chair:
Townsend, Timothy G
Committee Members:
Boyer, Treavor H
Chadik, Paul A

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Subjects / Keywords:
adsorption -- ammonia -- isotherm
Environmental Engineering Sciences -- Dissertations, Academic -- UF
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Environmental Engineering Sciences thesis, M.S.
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theses   ( marcgt )
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Abstract:
Treatment of municipal solid waste (MSW) landfill leachate is challenging because of its potential to contain a wide range of pollutants. Operators will often employ a combination of different treatment techniques to address these various pollutants. Reverse osmosis (RO) is one treatment method that can achieve full purification (rejection rates of 98-99%) of most leachate pollutants (Renou, 2008); however, ammonia-nitrogen is one pollutant that is difficult to remove using RO and still requires additional treatment. At the Alachua County Southwest Landfill (ACSWL), a research site located in Florida, a RO system is used to treat leachate from a closed MSW landfill. The system produces an effluent that meets state requirements for land application with the exception of ammonia-nitrogen concentrations exceeding the 2.8 mg/L threshold. A landfill operator could land apply the RO effluent to terrestrial crops; in this scenario the plants would uptake the remaining ammonia-nitrogen. An alternative approach would be to capture the nitrogen for beneficial use off-site. Landfill operators produce a large amount of woody biomass from yard waste collection; such material is typically low in nitrogen and high in carbon content. Research was conducted to evaluate whether the nitrogen content in the RO effluent could be adsorbed onto the woody biomass, thus forming a value-added product; a nitrogen-enriched mulch or compost. Chapter 2 of this thesis details a laboratory isotherm experiment evaluating the adsorption capacities of the woody biomass. The Freundlich isotherm was determined to be the best fit isotherm model to the experimental data. In comparison to other adsorbent materials, popular zeolites such as Clinoptilolite outperform the mulch; however, the mulch is comparable to other adsorbent materials such as soils. A theoretical ammonia-woody biomass adsorption system was developed from the experimental data. The results suggest a nitrogen-enriched mulch product could be produced from the adsorption system, yielding a fertilizer or compost product; however, in terms of ammonia-nitrogen removal, the woody biomass is better suited for a low volume system wherein the system produces low amounts of ammonia-nitrogen that need to be treated. Chapter 3 consists of passing the ACSWL RO system permeates through fixed bed columns containing the mulch. A high ammonia removal rate (>99%) was achieved through a two-step process of adsorption and nitrification. Degradation and composting were evaluated, in terms of percent carbon and nitrogen composition, dry weights, and carbon-to-nitrogen ratios, to determine the nutrient value of the mulch after the experimental period. Degradation and composting did occur within the mulch substrate because of a decrease in both mulch dry weights and C/N ratios; however, if the total amount of nitrogen added during the experiment period adsorbed onto the mulch substrate, the C/N ratios would not significantly reduce to optimal composting conditions. Further studies must be conducted to demonstrate the full effect of adding nitrogen to the mulch with the goal of decreasing the C/N ratio to composting conditions.
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In the series University of Florida Digital Collections.
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Includes vita.
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by James B Lloyd.
Thesis:
Thesis (M.S.)--University of Florida, 2012.
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Adviser: Townsend, Timothy G.
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RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2013-08-31

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1 SORPTION OF AMMONIUM DERIVED FROM MEMBRANE TREATED LANDFILL LEACHATE TO WOODY BIOMASS By JAMES LLOYD A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR TH E DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2012

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2 2012 James Lloyd

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3 To my mother, father, and sister

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4 ACKNOWLEDGMENTS I thank my committee chairman, Dr. Timothy Townsend, for his support and guidance H e has been a mentor to me caring, guiding me in the right research directions, and inspiring me to become a scientist and engineer. He has hel ped me at my most crucial times, providing advice when I needed it My journey to becoming a professional engineer from a non engineering background would not be possible without him; for that, I sincerely thank him I thank my other committee members, Dr. Treavor Boyer and Dr. Paul Chadik for their guidance and wisdom I also thank my fellow research group members for providing support thro ughout my graduate career I thank Alachua County Public Work s for providing the funds to make this research possible and giving me the opportunity to work on various solid waste projects. I thank my two mentors from Alachua County Public Works Ron Bishop and David Wood, for molding me into a n engineer. They ha ve provided invaluable lessons, both in the field and office, that applications) I also th ank them for teaching me how to write and professionally communicate as an engineer. I t hank my mom, dad, and my sister for their love and encouragement, and always supporting me throughout my studies. I especially thank my Dad for being a person I could always look to for advice

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5 TABLE OF CONTENTS page ACKNOWLEDGMENTS ................................ ................................ ................................ .. 4 LIST OF TABLES ................................ ................................ ................................ ............ 7 LIST OF FIGURES ................................ ................................ ................................ .......... 9 ABSTRACT ................................ ................................ ................................ ................... 11 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 14 1.1 Background and Problem Statement ................................ ................................ 14 1.2 Research Approach ................................ ................................ .......................... 15 1.2.1 Sorbate and Sorbent ................................ ................................ ............... 15 1.2.2 Experimental Approach ................................ ................................ ........... 16 1.3 Research Objectives ................................ ................................ ......................... 17 1.4 Organization of Thesis ................................ ................................ ...................... 18 2 AMMONIUM SORPTION TO WOODY BIOMASS USING LABORATORY BENCH SCALE ISOTHERM EXPERIMENTS ................................ ........................ 20 2.1 Background and Problem Statement ................................ ................................ 20 2.2 Materials and Methods ................................ ................................ ...................... 21 2.3 Results and Discussion ................................ ................................ ..................... 24 2.3.1 pH, Temperature, and Ionic Strength Effect on Ammoniated Solutions ... 24 2.3.2 Overall Sorption Capacities of Mulch ................................ ....................... 26 2.3.3 Isotherm Experiments ................................ ................................ .............. 28 2.4 Summary and Discussion ................................ ................................ ................. 34 3 AMMONIUM SORPTION TO WOODY BIOMASS USING FIXED BED COLUMNS ................................ ................................ ................................ .............. 44 3.1 Background and Problem Statement ................................ ................................ 44 3.2 Materials ................................ ................................ ................................ ........... 45 3.3 Methods ................................ ................................ ................................ ............ 47 3.4 Results and Discussion ................................ ................................ ..................... 49 3.4.1 Fixed Bed Column Expe riments ................................ .............................. 49 3.4.2 Overall Ammonia Removal Rates ................................ ............................ 50 3.4.3 Occurrence of Nitrite and Nitrate ................................ ............................. 51 3.4.4 Compost and Degradation of the Mulch ................................ .................. 55 3.5 Summary and Discussion ................................ ................................ ................. 58 4 SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS ................................ .. 71

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6 4.1 Summary of Results ................................ ................................ .......................... 71 4.2 Integration and Conclusion ................................ ................................ ............... 72 4.3 Opportunities for Future Work ................................ ................................ ........... 75 APPENDIX A DETAILED MULCH COMP OSITION ................................ ................................ ...... 77 B ANALYTICAL METHODS ................................ ................................ ....................... 78 C COMPOSTING AND DEGRADATION CONDITIONS ................................ ............ 80 LIST OF REFERENCES ................................ ................................ ............................... 81 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 83

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7 LIST OF TABLES Table page 1 1 Average Influent and effluent water quality of the RO leachate treatment system at the ACSWL during the first quarter of 2012 ................................ ........ 19 1 2 Brief description of the four mulch types used in the current study ..................... 19 2 1 Brief description of the four mulch types used the current study ........................ 37 2 2 Moisture, volatile solids, and elemental carbon and nitrogen content of the four mulch types ................................ ................................ ................................ 37 2 3 Particle size distribution analysis of the four mulch types (dried at 70 C) ........... 37 2 4 SSE values comparing NMF and OMF mulch types and NMC and OMC mulch types for determination of overall adsorption capacity order .................... 39 2 5 Comparison of Langmuir and Freundlich constants, correction coefficients (R 2 values) and MAPE and SSE values for the adsorption of ammoniated species to mulch ................................ ................................ ................................ 40 2 6 Comparison of the mulch used in the current study to other adsorbent materials found in literature ................................ ................................ ................ 41 2 7 Theoretical maximum adsorption capacities for the RO system effluents (first stage and second stage permeate) along with the observed (experimen tal) data for the RO system effluents with MAPE and SSE calculations ................... 43 3 1 Effluent and influent water quality of the RO system at the ACSWL ................... 60 3 2 Summary of the twelve mulch types used in the current study ........................... 60 3 3 Moisture, volatile solids, ash, carbon, and nitrogen content of the mulch used in the current study ................................ ................................ ............................. 60 3 4 Particle size distribution analysis of the four mulch types (dried at 70C) ........... 61 3 5 Dimensions of the fixed bed columns (in the form of buckets) used to hold the mulch during the experimental period ................................ ........................... 61 3 6 Nitrogen fate (as percent mass) in the fixed bed columns for weeks 6, 11, 15 ... 66 3 7 Moisture, volatile solids, ash, carbon, and nitrogen content along with C/N ratios before and after the experimental period for the twelve mulch types ........ 69 3 8 Commercial fertilizer product comparison to nitrogen enriched mulch ............... 70

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8 A 1 Carbon (C), Nitrogen (N), cellulose/hemicellulose (Cas), tannin (Csst), and lignin (Cl), contents for various woody biomass materials (Valenzuela Solano et al., 2006) ................................ ................................ ................................ ......... 77 B 1 Analytical methods for experimental parameters ................................ ................ 79

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9 LIST OF FIGURES Figure page 2 1 Determ ination of appropriate contact time by evaluating percent of ammonia adsorbed versus contact time ................................ ................................ ............. 38 2 2 Maximum adsorption capacities of the four mulch types after conducting isotherm experiments ................................ ................................ ......................... 38 2 3 Isotherm experimental r ) theoretical adsorption models based on experimental data A) NMF, B) NMC, C) OMF,D) OMC ................................ ...... 39 2 4 Experimental data ( ) for RO system effluents (first stage permeate) ( ) A) NMF, B) NMC, C) OM F,D) OMC ................................ ........................... 42 3 1 Fixed bed column (bucket) arrays at the experimental site ................................ 62 3 2 Schematic of the fixed bed column (bucket) used to hold the mulch samples .... 62 3 3 Nitrogen mass balance chart showing the fate of nitrogen throughout the fixed bed columns (buckets) ................................ ................................ ............... 63 3 4 Total ammonia nitrogen concentrations in the bottom bucket leachate for new mulch ................................ ................................ ................................ .......... 64 3 5 Total ammonia nitrogen concentrations in the bottom bucket leachate for old mulch ................................ ................................ ................................ .................. 64 3 6 Total ammonia nitrogen (left y axis) and nitrate nitrogen (right y axis) concentrations over time in the bottom bucket leachate for first stage permeate ................................ ................................ ................................ ............ 65 3 7 New mulch and old mulch wet weight over experimental period A) New mulch B) Old mulch ................................ ................................ ............................ 67 3 8 New mulch and old mulch depth (as measured from the top of the bucket to the surface of the mulch) over the experimental period ................................ ...... 67 3 9 Example of fungi growth within the fixed bed columns A) Mulch substrate B) Magnified view ................................ ................................ ................................ .... 68 4 1 Example of ammonia woody biomass adsorption system using the ACSWL RO permeate effluent as an example ................................ ................................ 76

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10 LIST OF ABBREVIATIONS ACSWL Alachua County Southwest Landfill CEC Cation Exchange Capacity DI Deionized FDEP Florida Department of Environmental Protection GWCTL Groundwater Cleanup Target Level HDPE High Density Polyethylene MAPE Mean Ab solute Percentage Error MSW Municipal Solid Waste NMC New Mulch Coarse NMF New Mulch Fine OMC Old Mulch Coarse OMF Old Mulch Fine RO Reverse Osmosis SSE Sum of Square Error

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11 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 SORPTION OF AMMONIUM DERIVED FROM MEMBRANE TREATED LANDFILL LEACHATE TO WOODY BIOMASS By James Lloyd August 2012 Chair: Timothy G. Townsend Major: Environmenta l Engineering Sciences Treatment of municipal solid waste (MSW) landfill leachate is challenging because of its potential to contain a wide range of pollutants. Operators will often employ a combination of different treatment techniques to address these v arious pollutants. Reverse osmosis (RO) is one treatment method that can achieve full purificat ion (rejection rates of 98 99%) of most leachate pollutants (Renou, 2008); however, ammonia nitrogen is one pollutant that is difficult to remove using RO and st ill requires additional treatment. At the Alachua County Southwest Landfill (ACSWL), a research site loc ated in Florida, a RO system is used to treat leachate from a closed MSW landfill. The system produces an effluent that meets state requirements for lan d application with the exception of ammonia nitrogen concentrations exceeding the 2.8 mg/L thresh old. A landfill operator c ould land apply the RO effluent to terr estrial crops ; in this scenario the plants would uptake the remaining ammonia nitrogen. An alt ernative approach would be to capture the nitrogen for beneficial use off site. Landfill operators produce a large amount of woody biomass from yard waste collection; such material is typically low in nitrogen and high in carbon content. Research was condu cted to evaluate whether the nitrogen content in the RO effluent could be adsorbed onto the

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12 woody biomass thus forming a value added product; a nitrogen enriched mulch or compost. Chapter 2 of this thesis details a laboratory isotherm experiment evaluatin g the adsorption capacities of the woody biomass. The Freundlich isotherm was determined to be the best fit isotherm model to the experimental data. In comparison to other adsorbent materials, popular zeolites such as Clinoptilolite outperform the mulch; h owever, the mulch is comparable to other adsorbent materials such as soils. A theoretical ammonia woody biomass adsorption system was developed from the experimental data. The results suggest a nitrogen enriched mulch product could be produced from the ads orption system, yielding a fertilizer or compost product; however, in terms of ammonia nitrogen removal, the woody biomass is better suited for a low volume system wherein the system produces low amounts of ammonia nitrogen that need to be treated. Chapter 3 consists of passing the ACSWL RO system permeates through fixed bed columns containing the mulch. A high ammonia removal rate (>99%) was achieved through a two step process of adsorption and nitrification. Degradation and composting were evaluated, in t erms of percent carbon and nitrogen composition dry weights, and carbon to nitrogen ratios, to determine the nutrient value of the mulch after the experimental period. Degradation and composting did occur within the mulch substrate because of a decrease i n both mulch dry weights and C/N ratios ; however, if the total amount of nitrogen added during the experiment period adsorbed onto the mulch substrate, the C/N ratios would not significantly reduce to optimal composting

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13 conditions. Further studies must be conducted to demonstrate the full effect of adding nitrogen to the mulch with the goal of decreasing the C/N ratio to composting conditions.

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14 CHAPTER 1 INTRODUCTION 1.1 Background and Problem Statement Municipal solid waste (MSW) management today consti tutes a major environmental, economical and social problem worldwide (Renou et al 2008) Landfilling continues to be the most effective and popular method for disposal of MSW in 2010, approximately 54% of MSW generated in the United States was landfil led (EPA, 2010). As landfilling continues to be implemented, leachate generated from landfil l cells will continue to be a problem. Landfill leachate is the aqueous effluent produced from rainwater percolation through the waste layers. Leachate can also ste m from inherent moisture within the waste contained in the landfill cell I t is characterized as a complex wastewat er and can contain many different types of pollutants including organic matter, ammonia nitrogen, heavy metals, and chlorinated organic and i norganic salts (Zouboulis and Petala, 2008; Renou et al 2008) These pollutants can make it difficult to implement treatment techniques to meet groundwater quality regulatory thresholds. Reverse osmosis (RO) treatment is one technique that can remove a majority of these pollutants ; however, ammonia nitrogen is o ne pollutant that is difficult to remove from leachate using RO techniques This is observed with the RO leachate treatment system at the Alachua County Southwest Landfill (ACSWL). The RO system a t the ACSWL is a two stage system that produces a clean effluent (permeate) and a rejected, more contaminated, effluent (concentrate). The permeate meets groundwater quality regulatory thresholds except for ammonia nitrogen. Table 1 1 shows the water quali ty for both stages of the system along with the influent ( raw leachate ) Currently, the

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15 second stage permeate is spray irrigated on the vegetation consumes the remaining ammonia nitrogen; however, r esearchers in the c urrent study evaluated methods to capture this residual nitrogen as a value added nutrient. In the current study, a method is explored to transfer the nitrogen found in the ACSWL RO system permeate onto woody biomass, another waste product often managed by landfill and waste station operators, aiming to create a value added biomass product that can be used as a fertilizer or compost 1.2 Research Approach 1.2 .1 Sorbate and Sorbent The current study evaluates the feasibility of transferring the nitrogen i n the sorbate) to woody biomass ( the sorbent). The sorbate originates from t he ACSWL site, located in the city of Alachua, Florida. The landfill began receiving waste in the 1970s and closed in 1999. During operation, approx imately 300 tons pe r day of MSW was disposed in the landfill. The AC S WL contains a 27 acre, class I lined solid waste cell that operates as a bioreactor (leachate is recirculated to promote waste stabilization). As p art of bioreactor operations, a RO syst em is used to partially treat the leachate produced from the lined cell. The RO system produces a clean effluent (permeate) and a more contaminated effluent (concentrate) wherein intermediate effluents (first stage concentrate, first stage permeate) and fi nal effluents (second stage concentrate, second stage permeate) are produced. Table 1 1 provides the water quality of the first and second stage permeates as well as the raw leachate from the landfill waste cell averaged during the first quarter of 2012 A s seen in Table 1 1 both permeate effluents exceed the F lorida Department of Environmental Protection (F DEP ) ammonia nitrogen groundwater cleanup target

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16 level (GWCTL) of 2.8 mg/L with first stage and second stage permeate containing an ammonia nitrogen co ncentration of 131 mg/L and 5.3 mg/L, respectively. The sorbent originates from the Alachua County solid waste transfer station located in the Leveda Brown Environmental Park in Gainesville, Florida. Biomass waste (consisting of wood and yard biomass mate rials) is accepted through a yard waste and woo d debris refuse service. The biomass waste consists of tree branches, twigs, leaves, pine needles, and other typical constituents of yard waste and wood debris. The woody biomass (mulch) is g round into a mulch product that is available for local resident s to pick up. Two mulch types were obtained from the collectio n facility, new and old mulch. New mulch refers to mulch that was stored at the transfer station for one month; old mulch was stored at the transfer station for one year. Each mulch type was processed separately through a high volume screener. Four mulch types were examined in this experiment: new fine mulch, new coarse mulch, old fine mulch, and old coarse mulch. Table 1 2 depicts the four mulch types abbreviations, ages, and particle size ranges. 1.2 .2 Experiment al Approach The approach to the current study begins with a laboratory isotherm experiment (Chapter 2) In this experiment the mulch is contacted with ammoniated solutions that vary in ammo nia nitrogen concentrations. Results will help determine the ability of the various mulch types to adsorb the ammoniated species from the solutions. The experimental data can be interpre ted into an isotherm model that can then be used to predict adsorption at varying ammonia nitrogen concentrations particularly in field applications Results determined in Chapter 2 will be the foundation for the field experiment conducted in Chapter 3 This experiment consists of passing the ACSWL

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17 RO system permeates throu gh fixed bed columns containing the mulch. Results of this experiment will help determine the amount of nitrogen (in the form of ammoniated feasibility of using the mul ch as a compost and/or fertilizer product. Comparisons will be made between both experiments to evaluate the ability to predict ammonia adsorption in field settings by models determined in the laboratory 1.3 Research Objectives Objectives for the laborato ry isotherm experiments (Chapter 2) are: Determine maximum adsorption capacities of the mulch Compare adsorption capacities of different mulch types (fine vs. coarse and new vs. old) Compare mulch adsorption behaviors to isotherm models, Langmuir and Freu ndlich, and determine which model best fits the experimental data. Compare mulch to other adsorbent materials in literature to evaluate relative adsorption performance. Evaluate the ACSWL RO system permeate under the laboratory isotherm experiments and com pare to theoretical isotherm models Develop an adsorption model to predict ammonia adsorption concentrations per mass of mulch. Objectives for the fixed bed column experiments (Chapter 3) are: Determine if the mulch (carbon rich source) can be used as com post after contact with ACSWL RO permeate (nitrogen rich source). Compare mulch (post experiment) with commercial fertilizer Compare the adsorption behavior of different mulch types (fine vs. coarse and new vs. old) Determine if isotherm models, develope d in Chapter 2, are able to predict ammonia nitrogen adsorption in the Chapter 3 experiment.

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18 1.4 Organization of Thesis Chapter 2 of this thesis consists of laboratory isotherm experiments. Chapter 3 examines fixed bed column experiments expanding up on Ch apter 2 results. The thesis ends with a summary and conclusions in Chapter 4. Appendices are presented at the end.

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19 Table 1 1 Average Influent and effluent water quality of the RO leachate treatment system at the ACSWL during the first quarter of 2012 P arameter Units Raw Leachate First Stage Second Stage pH SU 7.41 6.67 5. 31 Conductivity mho/cm 12520 2016 48 COD mg/L 1960 51 1 NH 3 N mg/L 980 131 5.3 Cl mg/L 1405 151 2.3 Table 1 2 Bri ef d escription of the four mulch types used in the current study Sample Type Abbr eviation Age Size New, Fine NMF One month old 12.7mm 6.35mm New, Coarse NMC One month old 12.7mm 6.35mm Old, Fine OMF One year old 6.35 mm .42mm Old, Coarse OMC One year old 6.35 mm .42mm

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20 CHAPTER 2 AMMONIUM SORPTION TO WOOD Y BIOMASS USING LABO RATORY BENCH SCALE ISOTHERM EXPER IMENTS 2.1 Background and Problem Statement Treatment of municipal solid waste (MSW) landfill leacha te is challenging b ecause of its complex chemistry and its potential to contain a wide range of polluta nts. Operators will often employ a combination of different treatment techniques to meet strict water regulatory st andards (Ahmed and Lan, 2012; Li et al 2009). Reverse osmosis (RO) is a treatment technique that can achieve full purificat ion (rejection r ates of 98 99%) of most leachate pollutants (Renou, 2008) ; however, ammonia nitrogen is one pollutant that is difficult to remove using RO and still requires additional treatment. Ammonia nitrogen occurs in relatively high co ncentrations in MSW leachate (5 00 2000 mg/L, Kjeldsen et al 2002) which makes it difficult to remove using RO membranes when meeting drinking water regulatory standards is required At the Alachua County Southwest Landfill (ACSWL), a research site located in Florida, a RO system is u sed to treat leachate from a closed MSW landfill. The system produce s an effluent that me e t s state requirements for land application with the exception of ammonia nitrogen concentrations exceeding the 2.8 mg/L threshold In one treatment scenario, a landfi ll operator could land apply the RO effluent to terrestrial crops in which the crops would uptake the remaining ammonia nitrogen; however, the capture of this nitrogen c ould be used more beneficially off site for more innovative applications. Landfill ope rators also produce a large amount of woody biomass from yard waste collection; such material is typically low in nitrogen and high in carbon content. Research was conducted to evaluate whether the nitrogen content in the RO effluent could be adsorbed onto the woody biomass thus forming a value added

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21 product a nitrogen enriched mulch or compost. Results of this study will determine the maximum amount of nitrogen (in the form of ammonia and ammonium) that is able to adsorb onto woody biomass. T hese data w ill be interpreted into an adsorption model that can be used to develop an ammonia woody biomass adsorption system and ultimately provide insight on the feasibility of creating a fertilizer or compost product. The objectives of this study are as follows: Observe the nature of ammonia adsorption onto woody biomass by compa ring isotherm adsorption models ( Langmuir and Freundlich ) and determining which model best fits the observed data. Determine the maximum adsorption capacities of the woody biomass. Compare different woody biomass types (e.g. ranges in particle sizes) and determine which is best for ammonia adsorption. Compare woody biomass to other adsorbent materials in literature to evaluate relative adsorption performance. Develop an adsorption model equ ation to predict the adsorption of ammonia species to woody biomass. 2.2 Materials and Methods Woody Biomass C haracterization Experiments were conducted using woody biomass obtained from a wood debris and yard waste refuse service located in a municipal s olid waste collection facility in Gainesville, Florida. The facility grinds the yard and wood debris into a mulch product. The specific species of the woody biomass (mulch) are not known; Appendix A provides ma terials that closely identify the mulch used in this study. Carbon, tannin, and lignin contents are also provided in Appendix A ; phenolic compounds such as tannin and lignin can increase ammonium adsorption via ion exchange and hydrogen bonding (Wahab et al ., 2010). The mulch is stored in piles at th e collection facility, exposed to the surrounding environment with the absence of

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22 any covering ; it is free of cost and abundant. The mulch was collected from specific p iles using large plastic bags. Table 2 1 depicts the four mulch types, abbreviations, ag es, and particle size ranges. Samples of new, old, fine, an d coarse mulch were collected. New mulch refers to mulch that was stored in pile s for one month. Old mulch was st ored in piles in for one year. The new and old mulch were processed separately throu gh a high volume screener to crea te fine and coarse categories. The different mulch types w ere stored in buckets at 4 C. The mulch was analyzed for its particle size distribution, moisture, volatile solids, ash, and total carbon and nitrogen contents. Tab le s 2 2 and 2 3 show the data for each sample type. A description of the analytical methods and instrumentation used in the current study are provided in Appendix B Isotherm experiments. The adsorption of ammonium onto mulch is examined through a series o f isotherm exper iments. The isotherm data help determine the adsorption capacity and character istics of the mulch and provide comparisons to other adsorbents in literature studies. Stock solutions of 1000 mg/L total ammonia nitrogen were prepared by dissol ving ammonium chloride (NH 4 Cl) salts into 1 liter of deionized (DI) water; 3.817 grams of NH 4 Cl was weighed on a digital sc ale. Approximately half of the weighed crystals were transferred to a 100 mL beaker; the beaker was filled with 50 mL of DI water and stirred until the salts disso lved into an aqueous solution. The solution was poured in to a 1000 mL volumetric flask. This step was repeated with the remaining half of the weighed crystals. The 100 mL beaker was rinsed with DI water and poured into the 10 00 mL volumetric flask to ensure that all NH 4 Cl salts were dissolved into the stock solution. This step was performed three times. The poured solution in the volumetric flask was diluted up to t he 1000 mL mark with DI water. All

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23 stock solutions were prepar ed on the day of the isotherm experiments. The pH of the solutions ranged from 8.0 to 8.5. Experiments were conducted to determine the appropriate contact time when the mulch reached an eq uilibrium adsorption capacity. 100 grams of NMF were added to three 2 liter H DPE containers (50 g/L dosage). The stock solution was then diluted to 500 mg/L NH 3 N and added to each contain er with the NMF. The containers were tumbled for 240 minutes. 1 mL samples were extracted using pipettes and analyzed at 5, 15, 30, 45, 60, 120, 1 80, and 240 minute time marks. The dependence of contact time on percent ammonia removed is shown in Figure 2 1. Equilibrium adsorption capacities were reached at the 45 minute time mark with a maximum total ammon ia nitrogen adsorption of 11%. Be tween the 60 and 240 minute time marks, the total NH 3 N con centrations stabilized at 11%. A total contact time of 60 minutes was used (instead of 45 minutes) to ensure equilibrium adsorption capacities were met during the batch experiments. The initial to tal NH 3 N concentrations used in the experim ent ranged from 0 to 500 mg/L. In addition to these concentrations, other ammoniated aqueous solutions were tested. The additional solutions were obtained from the RO system at the ACSWL. The RO system produces t wo effluents, first stage permeate and second stage permeate, that contain an NH 3 N concentration of 131 and 5 .3 mg/L, respectively. A contact time of 60 minutes, established in the sorption rate study, was uti lized in the batch experiments. Isotherm exper iments were conducted on different days for each initial NH 3 N concentration for a total of five days of elaps ed experiment time. For each day, twelve 2 liter HDPE contain ers were washed with DI water. The 12 containers consist of

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24 one container per mulch t ype (NMF, NMC, OMF, and OMC) measured in triplicate. Each container was washed three times with a solution of laboratory grade detergent and DI water. After cleaning with the detergent, the containers were rinsed thoroughly six times to ensure n o residual chemicals remained. The 1000 mg/L NH 3 N stock solution was then diluted to the prescribed initial concent ration for that day. Each prescribed solution was sampled; 2 mL of solution was extrac ted with an automatic pipette. The samples were stored in small cuvettes, and pH and temperature were measured in each solution before any contact with mulch; 200 grams of each mulch type was weighed using a digital scale. The mulch samples were transferred into their corresponding containers and the NH 3 N solutions we re poured into each container. The containers were tumbled for 60 minutes; after 60 minutes, 5 mL samples were extracted using an automatic pipette and then stored in small cuvettes. The samples were analyzed for total NH 3 N and pH within 10 minutes of sa mple extraction. 2.3 Results and Discussion 2.3.1 pH, Temperature and Ionic Strength Effect on Ammoniated Solutions Total ammonia in an aqueous solution consists of two principal forms, the ammonium ion (NH 4 + ) and un ionized ammonia (NH 3 ), with rela tive concentrations being pH, temperature and ionic strength dependent. The adsorption behavior of the mulch can be affected by the relative concentrations of NH 4 + and NH 3 in the solution. The two species of total ammonia, NH 3 and NH 4 + establish an equilibriu m following the equation: ( 2 1) The equilibrium relationship with relative activities is given by the following equation:

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25 (2 2) Equation 2 2 can be transformed to give th e ratio of NH 3 and NH 4 + in a particular solution: (2 3) Where g NH4+ is the activity coefficient of NH 4 + K a is the acid dissociatio n constant, and {H+} is the hydrogen ion activity. The pH range for the isotherm solutions before mulch co ntact was between 8.0 and 8.5. Solution temperatures were at 21 1 C for the experiment. By using equation 2 3 the ammonium ion perce ntage range wa s calculated at 86% to 96 %. This indicates that before the mulch was contacted, the ammonia species within the solution existed primarily as the ammonium ion. The dominance of ammonium ions along with a pH of 8.0 to 8.5 suggests favorable conditions for a dsorption, wherein significant biosorption can occur under high pH and alkaline conditions by polar grou ps of lignin within the mulch. Biopolymers, mainly lignin and cellulose chains, may become negatively charged, which enhances binding of the positively charged ammonium cations (Wahab et al., 2010). After the isotherm experiments were conducted, pH values were measured again. The solution pH values ranged between 6. 5 and 7.5 for all mulch types. The ionized ammonia percentage range was then calculated at 99 % to > 99% using equation 2 3 The pH decreased approximately 15% after the solutions cam e into contact with the mulch. This suggests that the pH of the mulch is less than t he pH of the aqueous solution. At a lower pH solution, ammonium has greater compe tition with H+ ions. As

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26 more cations are adsorbed, the surface of the mulch becomes positively charged which contributes to the decreasing adsorption capacity (Jang et al., 2005). 2.3.2 Overall Sorption Capacities of Mulch In order to investigate the effe ct of total NH 3 N concentration on the adsorption capacity of mulch, an equilibrium experiment was performed using a dosage of mulch (100 g/L) that was subjected to various concentrations of total NH 3 N ranging from 0 to 500 mg/L. A comparison of the maxim um adsorption capacities of the four mulch types to various NH 3 N concentrations in solution is shown in Figure 2 2 where Ce (mg/L) is the equilibrium total NH 3 N concentration and Qe (mg/g) is th e maximum adsorption capacity. Standard deviations show the error range in the results and are represented by error bars for individual data points. As seen in F igure 2 2 fine mulch exhibited greater adsorption capacity than coarse mulch. This is likely attributed to the fine mulch containi ng smaller particle siz es; due to a higher surface area more ammonium adsorption sites are available. To determine relative adsorption capacities between individual fine (NMF and OMF) and coarse mulches (NMC and OMC) further data evaluation was conducted. The sum of square erro r (SSE) was calcul ated for the experimental data. SSE is calculated by the following equation: ( 2 4 ) Where y i values. SSE cal culat ions, as shown in Table 2 4 distinguish adsorption capacities betwee n fine and coarse mulch types. A higher SSE, relative to the other mulch types, indicates that the data points for individual equilibrium concentrations are farther apart and relative ads orption capacities are easier to determine. SSE values were high for

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27 NMF an d OMF relative to NMC and OMC. This suggests favorab le determination, coupled with F igure 2 2 observations, that OMF exhibits a greater adsorption capacity than NMF. This is likely attributed to various physical characteristics: OMF contains smaller particles, as seen in T able 2 2 which indicates greater surface area for ammonium ions to be adsorbed; more pore spaces are also present which allows ammonium ions to be trapped. OMF co ntained the largest percentages of mulch in the mesh sizes of 20, 40, and the bottom pan (T able 2 3) The mulch in the bottom pan consists of the finest mulch constituents in the sample along with the inherent soil particles ; soil clay content and soil org anic matter content can provide high surface areas and active adsorption sites (Cox et al., 1993). Old mulch was exposed to the surrounding environment 11 months more than new mulch. Processes such as physical and chemical weathering can affect the surfac e characteristics of the mulch. Both processes promote the degradation of spaces, more surface area. Biodegradation (composting) can also occur when microorganisms break down the mu c oxygen promote this process. In the current study, old mulch was found (by researcher observations) to contain fewer leaves and less grassy material, which is indicative of biodegradation. This degradation can lead to increased pore spaces and greater mulch surface area. Coarse mulches (NMC and OMC) exhibited almos t equal adsorption capacities. A majority of the error bars for both mulch types overlapped, indicating ambiguity between relative ads orption capacities. In addition, SSE values for NMC and OMC were small compared to NMF and OMF; orders of magnitude ranged from 3 to 6, with three of the equilibrium concentrations containin g an order of magnitude of 4. As seen in the particle size dis tribution (table 2 3), OMC contains smaller mulch particles thus a higher surface area which suggests a higher adsorption potential; however, this higher surface area did not positively contribut e to OMC adsorption capacities. In addition, factors affectin g adsorption capacities as listed above (i.e. physical/chemical weathering and

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28 biodegradation) did not seem to significantly influence adsorption between old a nd new coarse mulch. The coarse mulches also contain minimal soil particles that can minimize act ive cation adsorption sites. Overall adsorption capacities observed for all mulch types decreased in 2.3.3 Isotherm Experiments An adsorption isotherm is any equation that relates the amount of adsorbate at the surface to the amount of adsorbate in solution when the s ystem has reached equilibrium. Equilibrium adsorption isothe rms are fundamentally important in the design of adsorption systems because they can predict the ability of a certain absorbent to remove a pollutant down to a specific discharge value. Langmuir and Freundlich isotherm models are used to describe the exper imental results of adsorption isotherms, specify the parameters that can be determined, compare the ammonium ion behavior, and determine the th eoretical adsorption isotherms. The isotherms are expressed by plotting the amount of ammonium ions held by the m ulch versus the equilibrium concentrations of total NH 3 N l ef t in the solution. Equations 2 5 and 2 6 show the Langmuir and Freundlic h isotherm models where Qe (mg/ g) is the amount of adsorbed ammonia per kilogram of woody biomass, Ce (mg/L) is the equilib rium concentration of ammonia, b (L/mg) is the Langmuir isotherm constant, Sm (mg/g) is the maximum adsorption capacity, Kf (L/g) is the Freundlich empirical constant, and n is related to the sorption intensity. The Langmuir isotherm: ( 2 5 )

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29 The Freundlich isotherm: ( 2 6 ) Both the Langmuir and Freundlich isotherm models were linearized to determine Langmuir model (one possible linearization) : ( 2 7 ) Freundlich model: (2 8 ) The linearized forms were plotted. Linear regressions were c onducted to determi ne the y intercepts and slopes. The y intercepts and slopes were then calculate d into the isotherm constants. Table 2 5 shows the isotherm constants (S m b, n, and K f ) derived from the linearized forms of the isothe rm models. SSE values were calculated between expe rimental and predicted values. Mean absolute percentage errors (MAPE) were also calculated, which indicates the fit between the experimental and predicted values of adsorption capacity MAPE is determined by the following equati on: ( 2 9 ) Where n is the number of experimental data. Figure 2 3 shows the superposition of experimental results (points) and the predicted calculated p oints (lines). The predicted solid phase loadings (adsorption densities) for all mulch types are higher than the Freundlich lines between equilibrium co ncentrations of 0 to 250 mg/L. After 250 mg/L, both lines intersect, at which point the maximum adsorption capacities for both mo dels are equal. After this intersection,

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30 Langmuir lines stabilize to their respective maximum adsorption capacities while Fre undli ch lines continue to increase. Both isotherm models follow their respective principles: Langmuir stabilizes due to monolayer adsorption while Freundlich increases due to multilayer adsorption. The ammonium adsorption onto the mulch best fit s the Freu ndlich model. As previously seen in Figure 2 2 the experimental data for all mulch types follow the same pattern high slope at low Ce values and a lower slope at higher Ce values (average slope between Ce values of 0 to 100 mg/L is 0.0033 L/g and betwee n 100 and 450 mg /L is 0.0014, a 57% decrease). This decrease follows the isotherm behavior of the ammonium ions as they reach adsorption equilibrium with the mulch (e.g., as seen in Jang et al., 2005 or Hamdaoui, 2007); however, the experimental data show that as equilibrium concentrations increase, the adsorption capacities continue to increase with minimal decline in adsorption rates; this suggests the experimental data could follow the Freundlich line. Freundlich SSE values for NMF, NMC, and OMC are less than the Langmuir values, which suggests a better fit for the Freundlich model, while SSE values for Langmuir are smaller for OMC, suggesting a better fit for Langmuir for that mulch type. MAPE percentages indicate favorable fits to Freundlich for NMF an d OMC, while Langmuir provides a better fit for NMC and OMF. The SSE and MAPE data suggest ambiguity for distinguishing the best isotherm fit for predicting over all mulch adsorption behavior. This ambiguity is likely attributed to the initial separation of the Langmuir a nd Freundlich predicted lines. Between equilibrium concentrations of 0 to 250 mg/L, Langmuir and Freundlich lines are relativel y close to each other. Difference calculations

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31 between the Langmuir and Freundlich predicted lines for equilibriu m concentrations of 0 to 250 mg/L were conducted by subtracting the Langmuir predicted value from the Freundlich predicted value for that specific C e value. The maximum distances observed for NMF, NMC, OMF, and OMC are 0.071, 0.033, 0.063, and 0.042 mg/g, respectively. This indicates that experimental values with higher standard deviation that are between both predicted lines can be assi gned to either isotherm model. For example, in Figure 2 3, the average adsorption capacity for NMF at 239 mg/L is 0.5817 mg/g 0.0503. The standard deviation range contains both Langmuir a nd Freundlich predicted lines. Average adsorption capacities were used in SSE and MAPE calculations excluding standard deviations; this exclusion can influence the SSE and MAPE values. T able 2 6 compares the results of the current study to other adsorbents found in literatu re. The source of the study and type of adsorbent are given in the first and second column s The reported maximum adsorption capacities ( S m ) are given in the third colu mn which compares the maximum amount of adsorbate (ammonium) that is able to adsorb onto that particular adsorbent. The fourth and fifth column s (Scenario 1 and Scenario 2) give a detailed comparison of the various adsorbents. Scenario 2 uses the Langmuir model (equation 2 5) to determine Q e values for comparison. Scenario 1 transforms equation 2 5 to calculate the required dosages for comparison: (2 10) Where C o is the initial total ammonia nitrogen concentration (mg/L), C e is the equilibrium total ammonia nitrogen concentration (mg/L), and D is the dosage (g/L). The effluent produced fr om the RO system at the ACSWL is used as a case study to set baseline parameters in both Scenario 1 and Scenario 2 The effluent from the RO system has an

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32 ammonia nitrogen concentration of 5.3 mg/L that exceeds the treatment target concentration of 2.8 mg/ L, the Florida Department of Environmental Protection (FDEP) Groundwater Cleanup Target Level (GWTCL). Scenario 1 compares the required dosages calculated using equation 2 10, for the various adsorbents; a lower dosage is optimal because less mass of the adsorbent is required. It specifies C o and C e where C o is 5.3 mg/L and C e is 2.8 mg/L. As seen in table 2 6 zeolite adsorbents re quire the least adsorbent mass. Natural zeolites such as clinoptilolite have been found very effective in removing ammonia fr om water by means of its excellent adsorpti on capacity (Du et al., 2003). Sawdust, an inexpensive biosorbent that is abundant in nature, requires a dosage amount of 9.6 g/L which is comparable to the zeolite materials. Sawdust, like the mulch used in this experiment, is high in polymeric materials such as lignin and tannins that can become negatively charg ed to adsorb ammonium cations. NMF and OMF were the most comparable to the other adsorbents with dosages at 160 and 177 g/L respectively. Both NMF and OM F were closest to the Haynie soil, as reported by Fernando et al (2005). Scenario 2 compares Q e values, the amount of ammonium able to adsorb per gram of adsorbent with C e being specified at 2.8 mg/L The three types of Clinoptilolites were the materials able to adsorb the most amount of ammonium per gram of Clinoptilolite NMF and OMF were most comparable to other adsorbents such as Sepiolite, reported by Bernal and Lopez Real (1993), and Kennebec and Haynie soil, reported by Fernando et al 2005. Isothe rm experiments were conducted mixing the mulch with two ammoniated effluents from a membrane filtration system that treats landfill leachate. The treatment system produces two effluents, first stage permeate and second stage permeate,

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33 containing total ammo nia nitrogen concentrations of 131 and 5 mg/L, respectively. The experiments yie lded isotherm data that compare the theoretical models with the experi mental data of both permeates. Table 2 7 compares the predicted adsorption capacity values to the adsorpti on capacities of the permeates, along with MAPE and SSE data. As seen in Table 2 7 Langmuir is more suitable for predicting the first and second stage p ermeate adsorption capacities. For first stage permeate, MAPE and SSE are lower for all mulch types for the Langmuir model. For second stage permeate, MAPE for Langmuir is lower than Freundlich f or all mulch types except NMC. Langmuir SSE values are also lower than F reundlich for all mulch types. These data suggest that Langmuir is better suited to predict field related adsorption capacities. The theoretical versus experimental values for first and second stage permeate are represented graphically in Figure 2 4 NMF and OMF yielded the closest capacities for Langmuir in which the predicted values are withi n the standard deviation ran ges for the experimental data. NMC adsorption capacities for Langmuir are also within the standard deviation range; however, the Freundlich predicted value is 2.9 mg/g below the standard deviation range. This suggests that the e xperimental data for NMC can follow either isotherm model. The OMC experimental data point for first stage permeate shows the greatest gap between the L angmuir and Freundlich models. Further experiments have to be conducted to determine if the experimental data follow a Langmuir or Freundlich model for all mulch types over larger equilibrium concentrations. Overall, Langmuir provided a better fit for both first and second stage permeate. The comparison of the theoretical values of the isotherm models to t he experimental adsorption capacities provides insight into the design of a mul ch

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34 ammonium adsorption system. The effluents from the RO system cont ain other chemical constituents; in contrast to the laboratory batch experiments which used aqueous solutions consisting of ammonium and chloride ions alon g with ammonia gas. In Figure 2 4 the first stage adsorption capacities for OMC were greater than th e theoretical isotherm models. This could indicate that the other constituents contained within the first sta ge permeate could positively influence the sorption mechanisms. NMF, NMC, and OMF stayed relatively close to the theoretical isotherm models, which indicate that if a mulch ammonia adsorption system were designed, the adsorption capacities could be predic ted by the theoretical isotherm models determined in this study. 2.4 Summary and Discussion The objectives set forth in the current study were met. The Freundlich isotherm was determined to be the best fit adsorption model. The mulch was compared to other adsorbents. NMF and OMF were the most comparable to the other adsorbents such as Haynie soil Comparisons between different mulch types were made; m ulches primarily consisting of fine particles can yield better adsorption capacities compared coarse mulches due to the fine mulches contained greater surface areas In addition, RO system effluents were contacted with the mulch; results suggested Langmuir was the best fit; however, further experiments must be conducted with varying concentrations to support thi s finding The results of the current study show that nitrogen (in the form of ammonia and ammonium) can adsorb onto the mulch thus suggesting a potential fertilizer or compost product; however, further analysis must be conducted to determine the practical use of mulch as a viable treatment option to remove high levels of nitrogen in a particular

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35 solution. The following is an example of an ammonia mulch adsorption system derived from the results of the current study The RO system at the ACSWL produces a se cond stage permeate that contains a total ammonia nitrogen concentration of 5.3 mg/L T he Freundlich adsorption model for NMF as determined in the current study, will be used to calculate the required amount of mulch needed per day to treat the ammonia to levels acceptable for discharge to groundwater per Florida requirements: ( 2 1 1 ) The desired ammonia nitrogen equilibrium concentration (C e ) for this example is 2.8 m illigrams/liter (the FDEP groundwater cleanup target level) ; this yields a Q e value of 0.0255 m illigrams /g ram The second stage ammonia nitrogen concentration of 5.3 m illigrams/liter is divided by 0.0255 m illigrams /g ram to yield a mulch dosage of approximately 208 grams of mulch per liter of second st age permeate produced from the RO system The system produces approximately 22,680 lite rs/day of second stage permeate. T his rate is multiplied by 208 grams/liter to yield a daily amount of mulch required of 4,717 kilograms which is the amount of mulch nee ded daily for treatment of the second stage permeate (5.3 mg/L ammonia nitrogen) to meet the FDEP groundwater cleanup target level of 2.8 mg/L. This suggests the mulch is not a viable treatment option for high flow rates ; however, the mulch could be favora ble for lower volume systems. In addition, the adsorbed nitrogen can still increase the nutrient value of the mulch. In this case, the mulch can be used to intermittently to capture the nitrogen in the second stage permeate and then used as a slow release fertilizer or composting product.

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36 To date, there is little research on ammonium sorption onto mulch ; further investigation is needed to examine the total ad sorption effectiveness of ammonia ted species to mulch. In addition, the mulch used in the current st udy consisted of various materials making the adsorbent surface more heterogeneous than in previous literature studies. For example, Jang et al (2005) determined that heavy metal adsorption onto hardwood bark was best de scribed as a Langmuir behavior. Wa hab (2010) described ammonium adsorption onto sawdust that also followed the Langmuir isotherm. In both cases, the researchers used a material that was more uniform than the mulch in the current study; both researchers also used a material comprised of a s ingle constituent (i.e. hardwood bark and sawdust, respectively). The current study presents an alternative use for two waste products generated by landfill operators: ammoniated effluent from leachate treatment and woody biomass from yard waste collection Although the mulch does not present a viable option for ammonia nitrogen removal at higher flow rates the mulch can be used intermittently to capture nitrogen from ammoniated solutions; in turn using the nutrient rich mulch as a slow release fertilizer or compost product.

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37 Table 2 1 Brief description of the four mulch types used the current study Sample Type Abbr eviation Age Size New, Fine NMF One month old 12.7mm 6.35mm New, Coarse NMC One month old 12.7mm 6.35mm Old, Fine OMF One year old 6.35 mm .42mm Old, Coarse OMC One year old 6.35 mm .42mm Table 2 2 Moisture, volatile solids, and elemental carbon and nitrogen content of the four mulch types Sample Type % Moisture Content % Volatile Solids % Ash %Carbon %Nitrogen 70 C 550 C NMF 41.2 77.5 16.4 41.3 0.63 NMC 38.7 81.2 6.5 45.8 0.51 OMF 36.5 66.4 25.0 37.2 0.73 OMC 43.1 72.3 17.7 40.4 0.48 Table 2 3 Particle size distribution analysis of the four mulch types (dried at 70 C) Mesh size Opening size ( m m ) % Retained NMF NMC OMF OMC 12.7 0 15 0 15 6.35 3 62 8 54 4 4 .76 21 8 11 9 10 2 .00 46 9 46 12 20 0.841 16 1 18 2 40 0.420 5 1 6 1 Pan < 0.420 9 5 12 8

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38 Figure 2 1 Determination of appropriate contact time by evaluating percent of ammonia adsorbed versus contact time Figure 2 2. Maximum adsorption capacities of the four mulch types after conducting isotherm experiments 0 0.2 0.4 0.6 0.8 1 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) NMF NMC OMF OMC

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39 Table 2 4 SSE values comparing NMF and OMF mulch types and NMC and OMC mulch typ es for determination of overall adsorption capacity order Equilibrium Concentration NMF and OMF NMC and OMC 3 5.78 x 10 5 9.00 x 10 6 73 2.50 x 10 3 9.00 x 10 4 215 1.07 x 10 2 1.00 x 10 4 239 8.18 x 10 4 6.05 x 10 4 440 2.12 x 10 2 1.00 x 10 3 A B C D Figure 2 3 Isotherm experimental results of the four mulch types along with and Freundlich ( ) theoretical adsorption models based on experimental data A) NMF, B) NMC, C) OMF,D) OMC 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L)

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40 Table 2 5 Comparison of La ngmuir and Freundlich constants, correction coefficients (R 2 value s) and MAPE and SSE values for the ad sorption of ammonia ted species to mulch Mulch Type Langmuir Freundlich S m b MAPE SSE K f n MAPE SSE mg g 1 L mg 1 % % NMF 1.026 0.0055 16. 33 0.0033 0.0126 1.458 8.58 0.0014 NMC 1.281 0.0021 10.89 0.0018 0.0036 1.159 13.01 0.0015 OMF 1.451 0.0035 9.46 0.0029 0.0076 1.228 12.74 0.0037 OMC 1.092 0.0028 11.02 0.0011 0.0052 1.255 6.10 0.0003

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41 Table 2 6 Comparison of the mulch used in the current study to other adsorbent materials found in literature Sour ce Adsorbent Maximum Adsorption Capacity, S m (mg/g) Scenario 1 a Dosage (g/L) Scenario 2 b Qe (mg/g) Bernal and Lopez Real 1993 Zeolite 1 8.149 4.9 0.513 Bernal and Lopez Real 1993 Zeolite 2 10.616 60 0.041 Bernal and Lopez Real 1993 Sepiolite 1.47 157 0.016 Current Study NMF 1.026 160 0.016 Current Study NMC 1.281 333 0.007 Current Study OMF 1.451 177 0.014 Current Study OMC 1.092 294 0.008 Fernando et al 2005 Kennebec soil 0.909 231 0.011 Fernando et al 2005 Haynie soil 0.217 190 0.013 Waha b et al 2010 S awdust 1.7 9.6 0.262 Wang et al 2006 Clinoptilolite 1 2.128 3.5 0.718 Wang et al 2006 Clinoptilolite 2 2.375 3.1 0.813 Wang et al 2006 Clinoptilolite 3 2.469 3.2 0.787 a Scenario 1 calculates the dosage, the amount of adsorbent ne eded per liter of solution with a specified initial total ammonia nitrogen concentration (C o ) of 5.3 mg/L and an equilibrium ammonia nitrogen concentration (C e ) of 2.8 mg/L b Scenario 2 calculates the Q e value, the a mount of ammonium (mg) adsorbed per gr am of adsorbent with a specified equilibrium concentration (C e ) of 2.8 mg/L.

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42 A B C D Figure 2 4 Experimental data ( ) for RO system effluents (first stage permeate) compared to the theoretical isotherm models and Freundlich ( ) A) NMF, B) NMC, C) OMF,D) OMC 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L) 0.0 0.2 0.4 0.6 0.8 1.0 0 100 200 300 400 500 Qe (mg/g) Ce (mg/L)

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43 Table 2 7 Theoretical maximum adsorption capacities for the RO system effluents (first stage and second stage permeate) along with the observed (experimental) data for the RO system effluents with MAPE and SSE calculations Mulch Type Theoretical Observed MAPE (%) SSE Langmuir Freundlich Langmuir Freundlich Langmuir Freundlich First Stage NMF 0.3563 0.2916 0.343 0.0 25 7.87 14.69 1.71 x 10 4 2.66 x 10 3 NMC 0.2398 0.2091 0.233 0.021 7.36 10.74 4.23 x 10 5 5.81 x 10 4 OMF 0.3694 0.3099 0.360 0.027 6.60 13.49 8.93 x 10 5 2.5 x 10 3 OMC 0.2377 0.2026 0.323 0.035 25.74 36.71 7.31 x 10 3 1.45 x 10 2 Second Stage NMF 0.0244 0.0352 0.0137 0.0012 79.94 159.3 1.15 x 10 4 4.64 x 10 4 NMC 0.0116 0.013 0. 0150 0.0017 21.28 12.39 1.1 x 10 5 3.99 x 10 6 OMF 0.0214 0.0242 0.0163 0.0006 31.27 48.90 2.61 x 10 5 6.39 x 10 5 OMC 0.0138 0.0175 0.0123 0.0012 13.52 43.20 2.53 x 10 6 2.73 x 10 5

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44 CHAPTER 3 AMMONIUM SORPTION TO WOODY BIOMASS USING FIXED BED C OLUMNS 3.1 Background and Problem Statement Ammonia nitrogen is a common aquatic pollutant that can be found in lakes, rivers, and drinking water reservoirs; it can stem from a variety of man made and natural sources. Ammonia levels exceeding 0.3 0.5 mg/ L (AWWA, 1990) can cause eutrophication growth of simple algae and pl ankton in bodies of water which decreases di ssolved oxygen concentrations. The removal of ammonia from these waters is important to meet env ironmental regulatory standards, and minimize groundwater con tamination and eutrophication. In the current study, ammonia contained in an effluent from a landfill leachate treatment system is examined. Landfill leachate is a wastewater produced mostly from rainfall percolation through a land fill was te mass. Ammonia concentrations within landfill leachate can range from 500 2000 mg/L, and concentrations within the waste mass do not decrease with time (Kjeldsen 2002 ). Several researchers have identified ammonia as the most significant component of l eachate for the long term ( Robinson, 1995; Krumpelbeck and Ehrig, 1999;Christensen et al., 1994; Christensen et al., 1999). Adsorption processes for ammonia removal typically use activated carbon and zeolites as the adsorbent; although these materials are effective, they are expensiv e compared to other adsorbents and the cost for regeneration processes can be expensive (Wahab, 2010). The current study examines woody biomass (mulch) as an alternative adsorbent for ammonia removal. The mulch is renewable, l ow cost, and can be used as a slow release fertilizer (the adsorbed ammonium as the nutrient) eliminating the need for regeneration processes.

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45 The previous study on ammonia adsorption onto mulch (chapter 2 of this thesis) show ed that the experimental mulch can adsorb nitrogen within a particular solution ; thus a slow release fertilizer or compost can potentially be produced. The goal of the current study is to apply the laboratory batch experiments in a field setting using fixed bed columns. The focus of ability to adsorb the ammonium and the compost ability and degradation of the mulch to further determine the use of the mulch as a nutrient product The results of this experiment can provide a case study for ammoni a adsorption onto the mulch; in such a case study, an adsorption system is developed that uses a material (mulch) tha t is low cost, renewable, and beneficial for use as a fertilizer. The objectives of this study are as follows: Determine if the mulch (carb on rich source) can be used as compost after contact with ACSWL RO permeate (nitrogen rich source). Compare mulch (post experiment) with commercial fertilizer. Compare the adsorption behavior of different mulch types (fine vs. coarse and new vs. old). Dete rmine if isotherm models, developed in Chapter 2, are able to predict ammonia nitrogen adsorption in Chapter 3 experiment. 3.2 Materials Sorbent and Sorbate. Experiments were conducted using woody biomass obtained from a wood debris and yard waste refuse s ervice located in a municipal solid waste collection fac ility in Gainesville, Florida. The facility grinds the yard and wood debris into a mulch product. The specific species of the mulch are not known; Appendix A provides mater ials that closely resemble t o the mulch used in this study. Carbon, tannin, and lignin contents are also provided in Appendix A ; phenolic compounds such as tannin and lignin can increase ammonium adsorption via ion exchange and hydrogen

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46 bonding (Wahab et al 2010). The mulch is stor ed in piles at the collection facility, exposed to the surrounding environment with the absence of any covering ; it is free of cost and abundant. The mulch was collected from specific p iles using large plastic bags. Table 2 1 depicts the four mulch types, abbreviations, ages, and particle size ranges. Samples of new, old, fine, a nd coarse mulch were collected. New mulch refers to mulch that was stored in piles for one month. Old mulch was st ored in piles in for one year. The new and old mulch w ere processed separately through a high volume screener to crea te fine and coarse categories. The different mulch types w ere stored in buckets at 4 C. The mulch was analyzed for its particle size distribution, moisture, volatile solids, ash, and total carbon a nd nitro gen contents. Table s 3 3 and 3 4 show the data for each sample type. A description of the analytical methods and instrumentation used in the current study is provided in Appendix B The sorbate (ammonium) originates from the Alachua County Southwest landfi ll (ACSWL) site located in the city of Alachua, Florida. The leachate from the landfill is treated by a two stage reverse osmosis (RO) system. The RO system produces a clean effluent (permeate) and a more contaminated effluent (concentrate) wherein interme diate effluents (first stage concentrate, first stage permeate) and final effluents (second stage concentrate, second stage permeate) are produced. Table 1 provides the water quality of the first and second stage permeates as well as the raw leachate from the landfill waste cell. According to the Florida Department of Environmental Protection (FDEP), the groundwater cleanup target level fo r ammonia nitrogen is 2.8 mg/L. As seen in Table 3 1, both permeate effluents exceed this discharge standard with first stage and second stage permeate containing an ammonia nitrogen concentration of

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47 131 mg/L and 5.3 mg/L, respectively. Both first and second stage permeates are used as the sorbates in the current study; deionized water is also used as the experiment blank. The mulch types and permeate effluents were combined to crea te a total of 12 sample types. Table 3 2 shows these sample types along with the associated abbreviations, age of the mulch, and particle size range. 3.3 Methods Fixed Bed Column Experiments. The fixed bed columns were in the form of buckets; Table 3 5 provides specific dimensions of the buckets and related experimental parameters Buckets used in this study were purchased from a local hardware store. A bucket was assigned to each of the 12 sample types listed in Table 3 2. Each sample type was measured in duplicate, equaling a total of 24 mulch buckets. Bucket configurations were assembled into arrays on a concrete pad. A picture of the array configuration is shown in Figure 3 1. The bucket arrays were covered by a metal roof to shield them from rainfall. When the site was vacant, a tarp was placed over the buckets as additional coverage to protect ag ainst strong winds and storms. Figure 3 2 shows a schematic of t he mulch bucket configuration. Hol es were drilled to perfor ate the bottom of each bucket. The mulch buckets were placed into another bucket labeled as the bottom bucket, as seen in Figure 3 2. The bottom bucket collects leachate effluent after the liquid percolates through the mulch and dr ains through the perforated bottom. Each collected mulch type was mixed thoroughly with a shovel for 5 minutes before being place into the individual mulch buckets. After each sample was mixed, the mulch was transf erred to the assigned buckets. The buckets were shaken to make sure settling occurred within the mulch bed. The mulch was filled in the buckets until a depth of 3 inches from the top of the bucket to the top of the mulch bed was achie ved. Lids

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48 were kept on the mulch buckets at all times e xcept dur ing a watering event. The lid was perforated by drilling holes into it, which allowed oxygen to enter the bucket to maintain an aerobic environment. The 24 mulch buckets were watered every week for nine week s and during weeks 11, 15, and 19. At the beginni ng of each watering event, each bucket was weighed on a digital scale; the weigh t of each bucket was recorded. The depth from the surface of the mulch to the top of the bucket was then measure d and recorded. The depth was determined with measuring tape at four equ idistant points on the bucket. The distances were averaged to determine the a verage depth of the mulch bed. The leachate effluent collected in the bottom bucket was then poured into a graduated cylinde r and the volume was recorded. Then 250 mL samp les were taken of the leachate effluent and p H measurements were conducted. The samples were stored at 4 C. After the leachate sample was collected, the mulch bucket was shaken for 2 m inutes for aeration. Between 1900 and 1925 mL of liquid influent per assigned bucket (either first or second stage permeate, or DI water) was measured a nd poured into a watering can. A watering can was used to water the mulch, distributing the liquid equ ally throughout the bucket area. A specific watering can was selected w ith a large spout to cover the area of the bucket equally when watering took place; the perforated lid was the n placed back onto the bucket. This process was carried out for each mulch buck et during every watering event. The leachate samples were analyzed within 48 hours of collection. Total ammonia nitrogen analysis was performed every w eek for the collected samples. A colorimetric method was used when analyzing the sample in a

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49 spectrop hotometer. Nitrate analysis was also performed in weeks 6, 11, and 15. A colorimetric method was also used for nitrate analysis using a spectrophotometer. 3.4 Results and Discussion 3.4.1 Fixed Bed Column Experiments Figure 3 3 shows a nitrogen mass balance for the mulch bucket experiments. Ammonium ions contained in the in fluent enter into the mulch buckets. The nitrogen species in the influent exist only as total ammonia nitrogen; the influent does not contain nit rite or nitrate concentrations. It should be noted that the ammonia species exists mostly as the ammonium ion d 6.5). In addition, concentrations or references to ammonia, ammonium, nitrite, and nitrate refer to the species as only nitrogen mass and not the total mass of the molecule. Once the ammonium enters the bucket, it follows one of two paths; it either adsorbs to the mulch or stays in solution res iding in the leachate effluent. If the ammonium is adsorbed onto the mulch, it can remain unchanged or undergo nitrification. In the case of nitrification, the nitrate species can desorb mainly because of the anionic character of the nitrates thus draining it to the leachate effluent c ollected in the bottom bucket. The nitrate species can also stay adsorbed onto the mulch, or the nitrate can be denitrified into elemental nitrogen gas and dissipa te into the atmosphere. If the ammonium does not adsorb onto the mulch, thus residing in the leachate effluent, the ammonium can either remain as ammonium in solution or underg o nitrification. If nitrification occurs, the nitrite and nitrate species can re main in solution or denitrify into elemental nitrogen gas and dissipate into the atmosphere. Due to the experimental methods, an exact measure of the total nitrogen mass balance will not be known; however, many conclusions can be drawn from the results.

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50 3. 4.2 Overall Ammonia Removal Rates Figure 3 4 shows the total ammonia nitrogen concentrations in the leachate eff luent over time for new mulch. First stage permeate contained an influent concentration of approximat ely 130 mg/L. During weeks 1 through 9, amm onia concentrations in the first stage leachate decreased with NMF decreasing faster than NMC. NMF contained smaller mulch particles that, compared to NMC, had more surface area and acted more as a filter bed, trap ping liquid within the column. Between we eks 9 and 19, ammonia concentrations were almost completely removed, which reduced concentrations in the leachate to below 0.5 mg/L. The second stage permeate contained approximately 5 mg/L ammonia in the influent. Between weeks 1and 6, concentrations for the second stage permeate and DI water stabilized between 1 and 10 mg/L ammonia nitrogen. During this time, ammonia concentrations in the second stage permeate did not reach significant removal. Between weeks 11 and 19, ammonia concentrations in second sta ge permeate and DI water achieved an ammonia removal rate of 90%; ammonia concentrations below 0.5 mg/L were achieved. Figure 3 5 shows the total ammonia nitrogen concentrations in the leachate effluent over ti me for old mulch. In weeks 1 through 9, ammoni a concentrations in the first stage leachate decreased, with O MF decreasing faster than OMC. Old mulch adsorption of first stage permeate was similar to new mulch in that the fine s exhibited better adsorption. This is likely attributed to the increased sur face area of the mulch and the fine mulch acting more as a filter bed compared to OMC. From weeks 9 to 19, ammonia concentrations were almost completely removed, which reduced concentrations in the leachate to below 0.5 mg/L. During weeks 1 to 9, second st age permeate and DI water bucket leachates r emained between 1 and 10 mg/L. Significant

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51 ammonia removal was not achieved during this time. Between weeks 11 and 19, second stage and DI effluents achieved an ammonia removal rate of 90% with concentrations bel ow 0.5 mg/L, with the exception of OMC DI which contained approximately 2 mg/L ammonia nitrogen at week 11 For all bucket types, approximately 100% ammonia removal was achieved during the later weeks of b ucket watering (i.e., weeks 11 to 19). Ammonia re moval was slower in the coarse mulche s compared to the fine mulches Although 100 % ammonia removal was achieved for fin e mulches at week 7; 100% ammonia removal was not achieved for the coarse mulches until week 11. In addition, between weeks 3 and 7, the ammonia nitrogen concentrations for fine mulches measured below 20 mg/L, which indicates that the fine mulch adsorb s ammonium faster than the coarse mulch. This can be attributed to the fine mulch acting more as a filter for the influent. In addition, th e fine mulch contains smaller mulch particles that indicate a greater surface area. 3.4.3 Occurrence of Nitrite and Nitrate Figure 3 6 shows total ammonia nitrogen and nitrate nitrogen versus time for the first stage permeate. The occurrence of nitrificat ion, as indicated by nitrite and nitrate concentrat ions, is important to observe. Autotrophic nitrification is associated with the bacteria o f the family Nitrobacteraceae. These nitrifiers are bacteria that grow by consuming inorganic nitrogen compounds. N itrifiers have a very limited range of substrates, either ammon ium or nitrite (Belser, 1979). In this study, nitrite is not present within the influent; therefore, the source of nitrogen is solely in the ammonia species. Populations and in situ activities of nitrifiers may commonly be limited by th e production rate of ammonium. This limitation occurs because the potential rate of ammonium

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52 oxidation can greatly exceed the rate of ammonif ication. This is commonly tested by adding ammonium to soils and observi ng stimulation in the growth of the nitrifier population; this is observed in the current study ammonium, the source of nitrogen, is added to the mulch substrate and, as a result, nitrification rates increase Belser (1979) examined the change in ammonia concentration as a function of ammonification and ammonium oxidation rate over a nitrifier growth pop ulation, as seen in Equation 3 1 : ( 3 1) where dS/dT is the change in the ammonium concentration with time (t), A is the cons tant rate of ammonium production due to ammonification, and r i s the ammonium oxidation rate. Ammonification is the process of organic nitrogen, in the form of dead organic matter, converted to inorganic nitr ogen, in the form of ammonium. For this study, a mmonification was assumed to not occur within the mulch because of the composition organic nitrogen is not readily available in mulch and the mulch contains minimal amounts of total nitrogen content (Appendix A ) that A r epresents the constant rate of inorganic ammonium added on a week ly basis to the mulch buckets. Belser explains that when the initial nitrifier population is low, r will be much less than A; therefore, the ammonium oxidation rate is much less than the cons tant amount of nitrogen added per week to the mulch buckets. As seen in Figure 6, total ammonia nitrogen concentrations in the leachate effluent were relative ly high between weeks 1 and 4. The nitrifier popul ations were low at this point. Belser noted that as bacteria populations increased, r increase d and at some point would be equal to A. At this point, dS/dT was 0 and the substrate concentration was at maximum. In this

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53 study, the nitrifier population never reached this point where r equaled A. The growt h of the nitrifier population was observed between weeks 6 and 11; however, nitrate concentrations reached a maximu m of approximately 60 mg/L in week 15. The ammonia nitrogen in the influent was never totally converted to nitrite and nitrate; therefore oth er factors might have inhibited the nitrifier population growth. Belser (1979) stated that physical parameters could produce enough stress to kill a portio n of the nitrifier population. Such conditions would cause declines in the populations obtained dur ing conditio ns of good growth and survival. If such adverse conditions were persistent, they would prevent the populations from ever reac hing their theoretical maxima. The two physical factors that seem to influence nitrifier populations the most are moist ure and temperature. Keeney and Bremner (1967) observed nitrification inhibition when soi ls reached 40 C. In the current study temperatures never reached 40 C; thus, temperature was not a factor in probable inhibition of the population growth. Dommergu es (1998) found that nitrification is inhibited under high moisture stress; other studies have shown that high moisture contents can decrease nit rification rates exponentially. This could influence the experimental results because the mulch had re ached max imum moisture uptake. Lastly, the mulch buckets could produce anaerobic environments that inhibit nit rite oxidation (Belser, 1979). All these factors could explain why total conversion of ammonium to nitrate did not occur. Table 3 6 shows the fate of the n itrogen in the mulch buckets as percent mass. The nitrogen fate was only determined in weeks 6, 11, and 15 because the nitrite and nitrate concentrati ons were analyzed at that time. In comparison to Figure 3 3 (nitrogen mass balance diagram), Table 3 6 do es not take into account the amount of nitrate

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54 denitrified from both the leachate effluent and mulch substrate. The nitrogen fate was divided into mass percentages of percent adsorbed on the mulch, the percent nitrified, and the percent of ammonia nitrogen that remained in the leachate effluent. As seen in week 6, a majority of the ammonium nitroge n was adsorbed onto the mulch. This data was consistent with Figure 3 6, which shows that adsorption oc curred in the beginning weeks. In addition, at week 6, NMC and OMC leachate efflu ents contained 23 and 56% residual ammonia, respectively. The fine mulch leachate efflu ents contained 1 and 5.5% residual ammonia. This is consistent with the determination that coarse mulch is a less effective adsorbent than fine mu lch (see Figure 3 6). In week 11, the percent of ammonium nitrified increased and the percent residual a mmonia decreased dramatically. This is consistent with the population growth of the nitrifiers and is consistent with Figure 3 6. In week 15, nitrificat ion percentages were greater than adsorption for th e removal of ammonia nitrogen. This indicates that the nitrifier population grew, which resulted in greater rates of ammonium oxidiza tion. At week 15, the percent of residual ammonia nitrogen for all mulch types was zero. Table 3 6 shows the ammonia nitrogen concentrations for the leachate effluent. In week 6, NMF was the only leachate effluent to meet the FDEP groundwater cleanup target leve l of 2.8 mg/L ammonia nitrogen. In weeks 11 and 15, the ammonia n itrogen concentrations were completely removed from the influent, which indicated that the effluent from the mulch buckets met th e FDEP ammonia nitrogen limit. These results were consistent with a previous study o f ammonium adsorption onto peat. Heavey (20 03) used columns containi ng peat as a treatment medium. In the experiment, landfill leachate was filtered through the peat columns to measure pre and post nitrogen

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55 species including ammonia n itrogen, nitrite, and nitrate. Heavey (2003) observed that the am monium was removed from the leachate through a two step physicochemical process of adsorption and nitrification. The ammonium would adso rb to the surface of the peat. Nitrifying bacteria located on the peat surface would then oxidize the am monium to nitrit e and nitrate. Heavey (2003) c oncluded that almost 100% of total ammonia nitrogen was removed from the leachate. The current study resulted in adsorption and ni trification yielding 100% ammonia removal. This removal of ammonia nitrogen indicates a potentia l treatment method by adsorption and nitrification in fixed bed reactors. 3.4.4 Compost and Degradation of the Mulch Physical characteristics of the mulch were examined to determine if degradation and composting had occurred during the experimental period. As seen in Figure 3 7, each mulch bucket weighed between 5.5 and 6 kg wet weight a t the start of the experiment. wet weight continued to in crease due to water retention. capacity was reached and its weight stabilized for th e remainder of the experiment. The stabilization of wet weight with no decline over the experimental period indicates signif icant degradation did not occur; however dry weights, before an d after the expe rimental period suggest that degradation did occur. Average dry weights for NMF, NMC, OMF, and OMC at week 1 were 3.2, 3.1, 3.4, and 3.0 kilograms, respectively; for week 19 the dry weights were 2.8, 2.5, 2.8, and 2.6 kilograms, respectively. Dry weight pe rcentage reductions for NMF, NMC, OMF, and OMC were 12.5, 19.3, 17.6, and 13.3% respectively over the experimental period The decline in dry weight over the experimental period suggests degradation did occur within the buckets.

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56 Figure 3 8 shows the dept h of the new and old m ulch contained in the buckets. The depth is measured from the top of the bucke t to the surface of the mulch. As seen in Figure 3 8, new and old mulch exhib ited almost the same behavior. The mulch depths for the various sample types st arted at approximately 3 inches and incr eased each week up to week 10. After week 10, the depths stabilized for th e remainder of the experiment. The bucket depth for all mulch types increased about 1.5 inches (from 3 to approximately 4.5 inches). The incre ase in depth can be attributed to mulch compaction within the buckets. During each watering event, the buckets were shaken to promote settling within the mulch particl es. The depth increase can also be attributed to degradation of the mulch Fungi growth w ithin the mulch medium was observed during the experiment period, as seen in Figure 3 9. Fungi, like bacteria, secrete enzymes to break down organic compounds that can aid in composting; however, fungi presence was minimal, which did not significantly cont ribute to the degradation of the mulch. Table 3 7 shows the mulch composition after the experiment period. Carbon and nitrogen composition percentages are given in the table along with the respective carbon/nitrogen (C/N) ratios before and after the expe rimental period The change in C/N ratios ( C/N) is also provided wherein a negative number indicates a decrease in C/N from before to after the experimental period. C/N ratios decreased for all mulch types. A typical C/N r atio for optimal composting condi tions is 25 40 (Golueke, 1991); this ratio was not achieved for NMC or OMC after the experimental period NMF and OMF achieved C/N ratios closest to 40, indicating the best potential for composting conditions. An optimal C/N ratio at the end of a compos ting period is 10 15:1 (Cornell Waste Management Institute, 1996) which was not achieved in the current study;

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57 composting occurred wherein carbon is lost via CO 2 emission durin g organic matter breakdown and nitrogen is increased due to the adsorption of nitrogen and the breakdown of organic matter C/N ratios of b oth fine mulches (NMF and OMF) are significantly lower than the course mulches. This can be attributed to the varying surface area between the fine and coarse mulches Most microbial activity occurs on the sur face of the organic particles. Fine mulch contains smaller particle sizes as seen in the particle size distribution analysis (t able 3 4) which encourage microbial a ctivity and incre ase the rate of decomposition. Decreasing particle size also increases the availability of carbon and nitrogen within the mulch substrate. The relatively small decrease of the C/N ratios within each mulch type could have been predicted by analyzing the nitrogen mass within the first and second stage permeate The total amount of nitrogen added to the first stage and second stage permeate buckets over the experimental period was 2,502 mg and 120 mg total ammonia nitrogen. The theoretical ni trogen composition if all the nitrogen added was adsorbed to the mulch, for first stage permeate buckets for NMF, NMC, OMF, and OMC is 0.68, 0.57, 0.78, 0.53 respectively; compared to the original nitrogen composition at 0.63, 0.51, 0.73, and 0.48%, resp ectively In addition, C/N ratios if all the nitrogen added was adsorbed to the mulch for the first stage permeate buckets, would be 57, 76, 49, and 81, respectively; compared to the original C/N ratios of 66, 91, 51, and 85. The theoretical values sugges t that the minimal decrease in C/N ratios, observed in the experimental data, could have been predicted. The amount of nitrogen applied to each bucket was relatively minimal compared to the amount of mulch present.

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58 Table 3 8 compares the nitrogen enriched m ulch to commercial fertilizers. The mulch contains minimal nutrient value relative to the other fertilizer products ; this is likely due to the small amount of nitrogen added to the mulch substrate during the experimental period. H owever, the benefits of using the mulch include it being free of cost and can also be used in an adsorption system which helps reduce ammonia nitrogen levels in solution In order to fully realize the benefits of the mulch, future studies must be conducted to demonstrate the ful l effect of adding nitrogen to the mulch with the goal of decreasing the C/N ratio to comp osting conditions. In such studies an influent containing a higher ammonia nitrogen concentration, than the influent used the current study (131 mg/L and 5.3 mg/L NH 3 N) shoul d be used. Results of such studies should then compare before and after C/N ratios and nitrogen composition of the mulch to evaluate the amount of n itrogen adsorbed. In addition, the mulch could then be compared to commercial fertilizers with th e intention of the mulch being comparable in nitrogen composition, in addition to the benefits of it being free of cost and reducing ammonia nitrogen levels in solution. 3.5 Summary and Discussion Fixed bed column studies were performed to study the ad sorp tion of ammonium to mulch. An ammoniated effluent generated from a leachate treatment system was passed through buckets (acting as the fixed bed columns) containing various mulch types. The main objectives of this study were to examine the adsorption capac ities and behaviors of the ammonia to the mulch and to determine if the mulch can be promoted as compost and fertilizer after it is contacted with a nitro gen source. A high ammonia nitrogen removal rate (>99%) was achieved through a two step process of ads orption and nitrification. This process was consistent with the findings of Heavey (2003),

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59 wherein pe at was contacted with ammonia. Complete nitrification of ammonia nitrogen to nitrate nitrogen was not observed during the experimental period In addition, nitrifying bacteria colonies were fully established at week 15 of the experimental period. Fine mulch exhibited greater adsorpti on capacity than coarse mulch. The fine mulch acted as a more effective filter than coarse mulch and also contained greater sur face area due to its smaller particle size. Degradation and composting did occur because of a decrease in both mulch dry weights and C/N ratios C/N ratios moderately decreased throughout the experimental period The inhibition of achieving optimal C/N r atios within the mulch substrate could be due to the high mulch water capacities, varying particle sizes, and low nitrogen availability. If all the nitrogen applied to the mulch buckets adsorbed onto the mulch, the amount of nitrogen would still be very mi nimal and would not cause a significant decrease in C/N ratios. The use of mulch as a media to remove total ammonia nitrogen from an aqueous solution through a two step mechanism of adsorption and nitrification is a feasible, inexpensive option. Water qual ity issues can arise in the contacted effluent, including an increase in turbidity and suspended solids. Future research needs to be conducted to determine the de adsorption capacities of the ammoniated mulch surface. Studies could be performed to attempt to quantity the amount of nitrogen that would de adsorb from the mulch. This would aid in determining if the mulch (with nitrogen adsorbed onto its surface) can act as a slow release nitrogen fertilizer.

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60 Table 3 1 Effluent and influent water quality of t he RO system at the ACSWL Parameter Units Raw Leachate First Stage Second Stage pH SU 7.41 6.67 5. 31 Conductivity mho/cm 12520 2016 48 COD mg/L 1960 51 1 NH 3 N mg/L 980 131 5.3 Cl mg/L 1405 151 2.3 Table 3 2 Summary of the twelve mulch types u sed in the current study Sample Type Effluent Abbr eviation Age Size New, Fine 1 st Stage NMF 1 One month 6.35 mm .42mm 2 nd Stage NMF 2 One month 6.35 mm .42mm Deionized Water NMF DI One month 6.35 mm .42mm New, Coarse 1 st Stage NMC 1 One month 12.7mm 6.35mm 2 nd Stage NMC 2 One month 12.7mm 6.35mm Deionized Water NMC DI One month 12.7mm 6.35mm Old, Fine 1 st Stage OMF 1 One year 6.35 mm .42mm 2 nd Stage OMF 2 One year 6.35 mm .42mm Deionized Water OMF DI One year 6.35 mm .42mm Old, Coarse 1 st Stage OMC 1 One year 12.7mm 6.35mm 2 nd Stage OMC 2 One year 12.7mm 6.35mm Deionized Water OMC DI One year 12.7mm 6.35mm Table 3 3 Moist ure volatile solids, ash carbon, and nitrogen content of the mulch used in the current study Sample T ype % Moisture Content % Volatile Solids % Ash %Carbon %Nitrogen C/N Ratio 70 C 550 C NMF 41.2 77.5 16.4 41.3 0.63 66 NMC 38.7 81.2 6.5 45.8 0.51 91 OMF 36.5 66.4 25.0 37.2 0.73 51 OMC 43.1 72.3 17.7 40.4 0.48 85

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61 Table 3 4 Particle size distribution analysis of the four mulch types (dried at 70C) Mesh size Opening size ( m m) % Retained NMF NMC OMF OMC 12.7 0 15 0 15 6.35 3 62 8 54 4 4.76 21 8 11 9 10 2.00 46 9 46 12 20 0.841 16 1 18 2 40 0.420 5 1 6 1 Pan <0.420 9 5 12 8 Table 3 5 Dimensions of the fixed bed columns (in the form of buckets) used to hold the mulch during the experimental period Parameter Units Bucket Diameter inches 11.5 Bucket Height inches 17.5 Weight of bucket kg 0.8 Mulch ma ss kg 5.3 6.1 Mulch height in bucket inches 14.5 Empty bucket volume ft 3 1.05 Mulch volume in bucket ft 3 0.87 Mulch density lb/ 3ft 13.4 15.5

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62 Figure 3 1 Fixed bed column (bucket) arrays at the experimental site Figure 3 2 Schematic of the f ixed bed column (bucket) used to hold the mulch samples

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63 a Influent contains nitrogen only in the form of total NH 3 N (TOTNH 3 N) Influent does not contain NO 2 N and NO 3 N species Figure 3 3 Nitrogen mass balance chart showing the fate of nitrogen thro ughout the fixed bed columns (buckets)

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64 Figure 3 4 Total ammonia nitrogen concentrations in the bottom bucket leachate for new mulch Figure 3 5 Total ammonia nitrogen concentrati ons in the bottom bucket leachate for old mulch

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65 Figure 3 6 Total a mmonia nitrogen (left y axis) and nitrate nitrogen (right y axis) concentrations over time in the bottom bucket leachate for first stage permeate

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66 Tabl e 3 6 Nitrogen fate (as percent mass) in the fixed bed columns for weeks 6, 11, 15 Sample Type Week 6 Week 11 Week 15 % Adsorb % Nitrify % NH 3 N NH 3 N (mg/L) % Adsorb % Nitrify % NH 3 N NH 3 N (mg/L) % Adsorb % Nitrify % NH 3 N NH 3 N (mg/L) NMF 81 19 1 1 75 25 0 0 79 21 0 0 NMC 57 20 23 23.5 61 39 0 0 36 64 0 0 OMF 77 18 5 5.5 77 23 0 0 52 48 0 0 OMC 40 5 56 60.5 52 48 0 0 36 64 0 0

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67 A B Figure 3 7 New mulch and old mulch wet weight over experimental period A) New mulch B) Old mulc h A B Figure 3 8 New mulch and old mulch depth (as measured from the top of the bucket to the surface of the mulch) over the experimental period 0 1 2 3 4 5 6 7 8 9 10 0 5 10 15 20 Wet Mulch Weight (kg) Week NMF-2 NMF-1 NMF-DI NMC-2 NMC-1 NMC-DI 0 1 2 3 4 5 6 7 8 9 10 0 5 10 15 20 Wet Mulch Weight (kg) Week OMF-2 OMF-1 OMF-DI OMC-2 OMC-1 OMC-DI 0 1 2 3 4 5 6 0 5 10 15 20 Inches Week NMF-2 NMF-1 NMF-DI NMC-2 NMC-1 NMC-DI 0 1 2 3 4 5 6 0 5 10 15 20 Inches Week OMF-2 OMF-1 OMF-DI OMC-2 OMC-1 OMC-DI

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68 A B Figure 3 9 Example of f ungi growth with in the fixed bed columns A) Mulch substrate B) Magnified view

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69 Table 3 7 Moisture, volatile solids ash, carbon, and nitrogen content along with C/N ratios before and after the experimental period for the twelve mulch types Sample Type % Moisture Content % Volatile Solids % Ash %Carbon %Nitrogen C/N Before C/N After C/N a 70 C 550 C NMF 64 29 7 40 0.75 66 53 13 66 26 8 39.2 0.8 66 49 17 DI 66 27 7 38.8 0.87 66 44 22 NMC 66 29 6 43.3 0.54 91 81 10 66 30 4 44 0.53 91 83 8 DI 65 32 3 44.7 0.56 91 80 11 OMF 66 27 7 38.5 0.93 51 41 10 69 23 8 38.8 0.95 51 41 10 DI 69 23 9 36.1 0.9 51 40 11 OMC 68 26 6 43.2 0.58 85 69 16 69 28 3 44.4 0.71 85 63 22 DI 70 27 4 43.1 0.57 85 76 9 a The change in C/N ratio before to after the experimental period. A negative number indicates a decrease in C/N from the start of the experiment.

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70 Table 3 8 Commercial fertilizer product comparison to nitrogen enriched mulch Fertilize r Product N P K Ratio Price Bat Guano 1 10 0.2 $8.50 Roots Organic Uprising Grow 6 0.5 1.5 $14.95 Milorganite Lawn Fertilizer 5 2 0 $12.95 Nitrogen Enriched Mulch (current study) 1 a 0 0 $0 a Nitrogen composition after the experimen tal period ranged fr om 0.53 0. 95%

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71 CHAPTER 4 SUMMARY, CONCLUSIONS AND RECOMMENDATION S 4.1 Summary of Results Ammonia nitrogen is one of the major long term pollutants found in landfill leachate ( Kjeldsen, et al, 2002) A mmonia is also problematic in other water sources s uch as potable water, wastewater, and general aqueous solutions. The removal of ammonia within these waters is important to minimalize adverse impacts to the environment. In the current study, mulch (chipped woody biomass product) was used as a low cost ad sorbent. The use of mulch as an adsorbent was hypothesized to remove ammonia nitrogen molecules from the wastewater thus decreasing the water toxicity. In addition, the transferred ammonia nitrogen, paired with the biodegradability of the mulch, would allo w the mulch to be used as a compost and fertilizer product. The present work demonstrates that mulch shows promise as a material to remove ammonium ions from an aqueous solution. Different mulch types yield varying adsorption results; mulches primarily co nsisting of fine particles can yield better adsorption capacities compared to mulches primarily consisting of coarse particles The fine particles contain greater surface area increasing the amount of adsorption sites Langmuir and Freundlich theoretical m odels were developed; the Freundlich theoretical model was best in describing ammon ium adsorption onto the mulch. The models can be used to develop a mulch ammonia adsorption system; however, high flow rates would be problematic as a large amount of mulch would be needed. The mulch is ideal for low volume systems where ammonia is removed from the pollut ed water and the captured nitrogen could be used as a fertilizer.

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72 Fixed bed column studies were performed to study the ad sorption of ammonium to mulch. An a mmoniated effluent generated from a leachate treatment system was passed through buckets (acting as the fixed bed columns) containing various mulch types. A high removal rate was achieved through a two step process o f adsorption and nitrification. This pro cess was consistent with the findings of Heavey et al. (2003) wherein ammonia from landfill leachate was contacted with peat beds Heavey et al. (2003) observed high ammonia nitrogen removal rates after initial adsorption and then eventual nitrification of the adsorbed ammonium ions on the peat surface Complete nitrification of ammonia nitrogen to nitrate nitrogen was not observed during the experimental period In addition, nitrifying bacteria colonies were fully established at week 15 of the experimental period. Fine mulch, compared to coarse mulch, exhibited faster adsorption rates The fine mulch acts more as a filter than coarse and also contains greater surface area due to smaller particle size. Degrad ation and composting was observed by a decrease in dry weight composition and C/N ratios. The inhibition of composting within the mulch substrate is likely due to high mulch water capacities, varying particle sizes, and low nitrogen availability. The use of mulch as a media to remove total ammonia nitroge n from an aqueous solution through a two step mechanism of adsorption and nitrification is a feasible, in expensive option. Water quality issues can arise in the contacted effluent such as an increase in turbidity and suspended solids. 4.2 Integration and Conclusion Below is an example of a pilot scale system, incorporating the results from chapter 2 and chapter 3 of this thesis, which could be implemented at the ACSWL for the RO system permeate. Figure 4 1 shows a flow chart detailing the process of the ad sorption

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73 system. The operator would extract the mulch from the yard waste collection area using an excavator or shovel. The mulch would then be processed into a high volume screener that would separate the mulch into fine and coarse categories. Mulch fines would be the most optimal to use in the adsorption system because of the results determined in both chapter 2 and 3 of this thesis. Next, the appropriate amount of mulch has to be calculated based on the permeate production rate for the RO system and the concentration of the ammonia in the RO permeate. The RO system at the ACSWL produces a second stage permeate that contains a total ammonia nitrogen concentration of 5.3 mg/L. The Freundlich adsorption model for NMF, as determined in the current study, will be used to calculate the required amount of mulch needed per day to treat the ammonia to levels acceptable for discharge to groundwater per Florida requirements: ( 2 8 ) The desired ammonia nitrogen equilibrium concentration (C e ) for this example is 2.8 milligrams/liter (the FDEP groundwater cleanup target level); this yields a Q e value of 0.0255 milligrams/gram. The second stage ammonia nitrogen concentration of 5.3 milligrams/liter is divided by 0.0255 milligra ms/gram to yield a mulch dosage of approximately 208 grams of mulch per liter of second stage permeate produced from the RO system. The system produces approximately 22,680 liters/day of second stage permeate. This rate is multiplied by 208 grams/liter to yield a daily amount of mulch required of 4,717 kilograms which is the amount of mulch needed daily for treatment of the second stage permeate (5.3 mg/L ammonia nitrogen) to meet the FDEP groundwater cleanup target level of 2.8 mg/L. This amount of mulch would be placed

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74 inside a mulch flow reactor as seen in F igure 4 1 The permeate would passively flow through the reactor using gravity and the residual pressure from the permeate pipeline. The size of the r eactor would be calculated so that the total time of the permeate spent in the reactor is 45 to 60 minutes. The effluent from the reactor would be analyzed for ammonia nitrogen; then, if it meets the Florida groundwater discharge requirement, the effluent w ould be discharged to groundwater. The mulch ins ide the reactor will be replaced every day. The extracted mulch from the reactor c ould then be used as mulch around t he city landscape. The mulch could be marketed to citizens and entities as a nutrient enriched fertilizer produced from the combination of two waste materials: treated leachate and woody biomass from yard waste collection. The amount of mulch needed to fill the reactor per day at the ACSWL RO system is impractical at 4,717 kilograms per day This suggests the mulch is not a viable treatment option for high flow rates; however, the mulch could be favorable for lower volume systems. In addition, the adsorbed nitrogen can still increase the nutrient value of the mulch. In this case, the mulch can be use d intermittently to capture the nitrogen in the second stage permeate and then used as a fertilizer or composting product. T he second stage permeate can also be directly sprayed onto the mulch piles, either at the yard waste collection facility or a transported mulch pile placed at the ACSWL where the RO system is located. In this scenario, the ammonia nitrogen woody biomass adsorption system process is simpler by direct discharge of permeate onto the mulch ; however, target equilibrium concentrations might not be achieved because of minimal contact time between the permeate and the mulch

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75 4.3 Opportunities for Future Work To date, there is little research on ammonium sorption onto mulch Ammonia nitrogen is not a limited resource; alternatively, nutrients such as pho sphorus, are scarcer and more wide ly researched. However, h igh levels of nitrogen in water bodies can cause toxic conditions ; therefore cheap, renewable methods to remove nitrogen from these waters could be desirable. In addition, further research must be conducted to evaluate lower equil ibrium ammonia nitrogen concentrations (e.g. 0 to 10 mg/L). For instance, in the case of the RO system at the ACSWL, the effluent contains 5.3 mg/L ammonia nitrogen. In the current study, equilibrium ammonia nitrogen concentrations between 0 to 500 mg/L we re studied; this range is large compared to the smaller range needed to study the RO effluent case study. Lastly chapter 3 results showed that the permeate added to the mulch buckets was insignificant and did not demonstrate the therefore, more studies need to be conducted, using higher nitrogen concentrations applied to the mulch substrate, to demonstrate the compost and degradation ability of the mulch. Overall, the results of this study prove that mulch can adsorb nitrogen; fur ther case studies must be conducted to determine this would be applied in field applications.

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76 Figure 4 1 Example of ammonia woody biomass adsorption system using the ACSWL RO permeate effluent as an example

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77 APPENDIX A DETAILED MULCH COMPO SITION Ta ble A 1. Carbon (C), Nitrogen (N), cellulose/hemicellulose (Cas), tannin (Csst), and lignin (Cl), contents for various woody biomass ma terials (Valenzuela Solano et al. 2006) Woody Biomass Materials Type % Composition C N C as C l C sst Shredded redwood Shredded timber 48.5 0.3 51.8 42.7 5.1 Grass clippings Fescue mowing residuals 42.2 3.9 58.6 11.1 26 Oleander yardwaste Leaves and branch pieces 46.9 0.8 64.3 15.6 14.7 Eucalyptus yardwaste Leaves and branch pieces 47.5 1.3 55.0 21.9 18.4 Pine yardwast e Needles and branch pieces 49.2 0.7 46.9 24.5 17.4 Compost Commercially composted forest residuals 47.5 0.6 67.7 28.3 3.6

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78 APPENDIX B ANALYTICAL METHODS Moisture content was determined by oven drying the mulch for 24 hours at 70 C. Moisture content for the various t ypes ranged from 6 to 12% The oven dried mulch was ignited in an oven at 550 C for 30 minutes per sample to determine the volatile solids content, which ranged from 66 to 82% After the samples were ignited at 550 C, the leftover mat erial was designated as the ash content. Ash content percent ages varied from 6 to 25% Oven dried mulch was also analyzed for total carbon and nitrogen content. Carbon content was in the range of 37 to 46% Particle size distribution analysis was perfor med on the oven dried mulch Mesh sizes of 12.7 millimeters (mm) to 0.420 mm (b ottom pan collected residuals) were selected for particle size distribution analysis. Coarse mulch size ranges between 6.35 mm to 12.7 mm. T he majority of coarse mulch was retai ned at the 6.35 mm sieve size with NMC and OMC at 62 and 54% retained, respectively. Fine mulch size ranges from 0.42 to 6.35 mm including a pan catching the residual mulch. The majority of fine mulch reported at 2.00 mm sieve size with both NMF and OMF re porting 46% retained. The percentages of material retained in the bottom pan ranges from 5 to 12% across the various mulch types. These percentages are significant because this portion represents the mulch pa rticles smaller than 0.42 mm. They also represen t part of the soil content contained in samples. The various mulch samples inherently contained soil particles adhered to the mulch chips. After the mulch is oven dried the soil particles are detached from individual mulch chips then sieved through the pa rticle size distribution analysis where the soil particles were collected in the bottom pan.

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79 Table B 1. Analytical methods for experimental parameters Measurement Instrumentation pH pH electrode Temperature Digital probe Moisture content Oven Volatile solids Oven Particle size distribution Mechanical screener Carbon, nitrogen content Carlo Erba NA1500 CNHS Analyzer Ammonia nitrogen HACH DR/4000 Spectrophotometer

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80 APPENDIX C COMPOSTING AND DEGRA DATION CONDITIONS In this study, it was hypothesized t hat composting would be favorable due to the following: The mulch contains high carbon content, which serves as an energy source for the cells; some of the energy formed is used for microbial metabolism, and the rest is released as heat. The permeate adds nitrogen in the form of ammonia to the mulch every week during a watering event. The nitrogen is a critical element for microorganisms because it is a component of the prot eins, nucleic acids, amino acids, enzymes, and co enzymes necessary for cell growth and functioning (Tuomela et al., 2000). The shaking of the buckets adds oxygen to the mulch substrate. Oxygen is needed for degradation; microbes advance the degradation p rocess by breaking down organic matter, utilizing the carbon as an energy source wherein oxygen acts as the electron accepter. The permeate added each week to the mulch was the source of water, which was critical to maintaining optimal composting condition s. Areas of this experiment that could inhibit the composting of the mulch are as follows: The optimal carbon/nitrogen ratio for composting is 25 40 (Golueke, 1 991). The mulch inherently has a large carbon content, but has minimal nitrogen content as seen in Table 4. Carbon/nitrogen (C/N) ratios for the collected mulch for NMF, NMC, OMF, and NMC are 66, 91, 51, and 85, respectively. The high moisture content o f the mulch can cause a lack of aeration and leaching of the nutrients. Anaerobic conditions can be created that decrease the decomposition rate (Golueke, 1991). The mulch contains high lignin and cellulose contents that make degrading the material diffi cult for microorganisms.

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81 LIST OF REFERENCES Ahmed, Farah Naz, and Christopher Q. Lan. "Treatment of Landfill Leachate Using Membrane Bioreactors: A Review." Desalination 287 (2012): 41 54. A merican Water Works Association 1990. Water Quality and Treatment. McGraw Hill, New York. Bels er, L. W. Population Ecology of Nitrifying Bacteria. California: Annual Reviews, 1979. Bernal, M. and Lopez Real. "Natural Zeolites and Sepiolite as Ammonium and Ammonia Adsorbent Materials." Bioresource Technology 43.1 (1993): 27 33. Christensen, J.B., Je nsen, D.L., Filip Z., Gr o n C., and Christensen T.H., Characterization of the dissolved organic carbon in landfill polluted groundwater, Water Res., 32, 125, 1998. Christensen, T.H., Kjeldsen, P., Albrechtsen, H. J., Heron, G., Nielsen, P.H., Bjerg, P.L., a nd Holm, P.E., Attenuation of landfill leachate pollutants in aquifers, Crit. Rev. Environ. Sci. Technol., 24, 119, 1994. Cornell Waste Management Institute. "The Science of Composting." Composting Web. < http://cwmi.css.cornell.edu/chapter1.pdf >. Cox, L., M. Hermosin, and J. Cornejo. "Adsorption of Methomyl by Soils of Southern Spain and Soil Components." Chemosphere 27.5 (1993): 837 49. Dommergues, Y.R., Belser, L. W., Schmidt, E. L. 198. Adv. Microb. Ecol. 2:49 104 Fernando, W. A. R. Nishantha, Kang Xia, and Charles W. Rice. "Sorption and Desorption of Ammonium from Liquid Swine Waste in Soils." Soil Science Society of America Journal 69.4 (2005): 1057. Golueke, C.G. Principles in Composting: The Staff of Biocycle Journal of Waste Recy cling. The Art and Science of Composting. Pennsylvania: The JG Press Inc., 1991. pp 14 27 Hamdaoui, O., and E. Naffrechoux. "Modeling of Adsorption Isotherms of Phenol and Chlorophenols onto Granular Activated CarbonPart I. Two parameter Models and Equat ions Allowing Determination of Thermodynamic Parameters." Journal of Hazardous Materials 147 .1 2 (2007): 381 94. Heavey, M. "Low cost Treatment of Landfill Leachate Using Peat." Waste Management 23.5 (2003): 447 54. Jang, A., Y. Seo, and P. Bishop. "The Re moval of Heavy Metals in Urban Runoff by Sorption on Mulch." Environmental Pollution 133.1 (2005): 117 27.

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82 Keeney, D.R., Bremner, J.M. 1967 Soil Sci. Soc. Am. Proc. 31:34 39 Kjeldsen, Peter, Morton A. Barlaz, Alix P. Rooker, Anders Baun, Anna Ledin, and T homas H. Christensen. "Present and Long Term Composition of MSW Landfill Leachate: A Review." Critical Reviews in Environmental Science and Technology 32.4 (2002): 297 336. Environmental Protection Agency. Municipal Solid Waste Generation, Recycling, and Disposal in the United States: Fac ts and Figures for 2010 Rep. W eb. < http://www.epa.gov/osw/nonhaz/municipal/pubs/msw_2010_factsheet.pdf >. Renou, S., J.G. Givaudan, S. Poul ain, F. Dirassouyan, and P. Moulin. "Landfill Leachate Treatment: Review and Opportunity." Journal of Hazardous Materials 150.3 (2008): 468 93. Robinson, H.D., The technical aspects of controlled waste management. A review of the composition of leachates f rom domestic wastes in landfill sites. Report for the UK Department of the Environment. Waste Science and Research, Aspinwall & Company, Ltd., London, UK, 1995. Tuomela, M. "Biodegradation of Lignin in a Compost Environment: A Review." Bioresource Technolo gy 72.2 (2000): 169 83. Valenzuela Solano, C., and D. Crohn. "Are Decomposition and N Release from Organic Mulches Determined Mainly by Their Chemical Composition?" Soil Biology and Biochemistry (2005). Wahab, Mohamed Ali, Salah Jellali, and Naceur Jedidi. "Ammonium Biosorption onto Sawdust: FTIR Analysis, Kinetics and Adsorption Isotherms Modeling." Bioresource Technology 101.14 (2010): 5070 075. Wang, Y., S. Liu, Z. Xu, T. Han, S. Chuan, and T. Zhu. "Ammonia Removal from Leachate Solution Using Natural Ch inese Clinoptilolite." Journal of Hazardous Materials 136.3 (2006): 735 40. Zouboulis, A.i., and M.d. Petala. "Performance of VSEP Vibratory Membrane Filtration System during the Treatment of Landfill Leachates." Desalination 222.1 3 (2008): 165 75.

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83 BIOG RAPHICAL SKETCH James Lloyd earned his Bachelor of Science d egree in Building Construction from the University of Florida in 2010. He decided to follow his engineering passion and enrolled in graduate school in the Environmental Engineering Sciences Depart ment in fall 2010.