in-situ ammonia removal of leachate from bioreactor landfills

345 Pages·2006·3.52 MB·English

by  Nicole Berge

IN-SITU AMMONIA REMOVAL OF LEACHATE FROM BIOREACTOR
LANDFILLS

by

NICOLE D. BERGE
B.S. University of South Carolina, 1999
M.S. University of South Carolina, 2001

A dissertation submitted in partial fulfillment of the requirements
for the degree of Doctor of Philosophy
in the Department of Civil and Environmental Engineering
in the College of Engineering and Computer Science
at the University of Central Florida
Orlando, Florida

Spring Term
2006

Major Professor: Debra R. Reinhart
ABSTRACT

A new and promising trend in solid waste management is to operate the landfill as
a bioreactor. Bioreactor landfills are controlled systems in which moisture addition and/or
air injection are used as enhancements to create a solid waste environment capable of
actively degrading the biodegradable organic fraction of the waste. Although there are
many advantages associated with bioreactor landfills, some challenges remain. One such
challenge is the ammonia-nitrogen concentration found in the leachate. The
concentrations of ammonia-nitrogen tend to increase beyond concentrations found in
leachate from conventional landfills because recirculating leachate increases the rate of
ammonification and results in accumulation of higher levels of ammonia-nitrogen
concentrations, even after the organic fraction of the waste is stabilized. Because
ammonia-nitrogen persists even after the organic fraction of the waste is stabilized, and
because of its toxic nature, it is likely that ammonia-nitrogen will determine when the
landfill is biologically stable and when post-closure monitoring may end. Thus an
understanding of the fate of nitrogen in bioreactor landfills is critical to a successful and
economic operation.
Ammonia-nitrogen is typically removed from leachate outside of the landfill.
However, additional costs are associated with ex-situ treatment of ammonia, as separate
treatment units on site must be maintained or the leachate must be pumped to a publicly
owned wastewater treatment facility. Therefore, the development of an in-situ nitrogen
removal technique would be an attractive alternative. Several recent in-situ treatment
approaches have been explored, but lacked the information necessary for field-scale
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implementation. The objectives of this study were to develop information necessary to
implement in-situ ammonia removal at the field-scale.
Research was conducted to evaluate the kinetics of in-situ ammonia removal and
to subsequently develop guidance for field-scale implementation. An aerobic reactor and
microcosms containing digested municipal solid waste were operated and parameters
were measured to determine nitrification kinetics under conditions likely found in
bioreactor landfills. The environmental conditions evaluated include: ammonia
concentration (500 and 1000mg N/L), temperature (25o, 35o and 45oC), and oxygen
concentration in the gas-phase (5, 17 and 100%).
Results suggest that in-situ nitrification is feasible and that the potential for
simultaneous nitrification and denitrification in field-scale bioreactor landfills is
significant due to the presence of both aerobic and anoxic areas. All rate data were fitted
to the Monod equation, resulting in an equation that describes the impact of pH, oxygen
concentration, ammonia concentration, and temperature on ammonia removal. In order to
provide design information for a field-scale study, a simple mass balance model was
constructed in FORTRAN to forecast the fate of ammonia injected into a nitrifying
portion of a landfill. Based on model results, an economic analysis of the in-situ
treatment method was conducted and compared to current ex-situ leachate treatment
costs. In-situ nitrification is a cost effective method for removing ammonia-nitrogen
when employed in older waste environments. Compared to reported on-site treatment
costs, the costs associated with the in-situ ammonia removal process fall within and are
on the lower end of the range found in the literature. When compared to treating the
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leachate off-site, the costs of the in-situ ammonia removal process are always
significantly lower. Validation of the laboratory results with a field-scale study is needed.
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ACKNOWLEDGMENTS

First and foremost, I would like to begin by thanking my advisor, Dr. Debra
Reinhart, without whom this work would not have been possible. Dr. Reinhart has played
many roles during my time here. She has been an extraordinary role model, mentor,
friend and critic, exerting an influential impact on my future and helping to shape me
both as an aspiring researcher and teacher. She has taught me how to be strong, positive,
and have confidence, as she always had immense confidence in me. I have also learned
from her the role teaching and research have in life and how much passion for both
makes all the difference. I also thank her for providing me with numerous professional
development opportunities, such as teaching and attending many conferences. Her
willingness to reply to the countless daily emails I sent and for always being available
when I needed to blow off steam have been invaluable. One truly could not ask for a
better mentor and I feel blessed to have had the opportunity to get to know and work with
her. I truly believe that I am leaving UCF not only with a better understanding of theories
and as a better researcher, but also as a better person because of all I learned from her.
I would also like to thank Dr. John Dietz for all of his help during the past few
years. Thank you, Dr. Dietz, for being so helpful and gracious with your time. I have
learned so much from you. Dr. Dietz always dropped by my office to help with my, at
times quite numerous, problems or to give advice as to how to interpret results. He taught
me how to be critical of all results and how to truly understand the inherent limitations
associated with them. His help and expertise were invaluable to this work and I really
cannot express the immense gratitude I have for all he has done for me. And yes, Dr.
Dietz, I did finish before you retired! I just made it…barely!
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I also would like to thank my other committee members. Dr. Tim Townsend has
offered invaluable guidance to this work. His comments and critiques have made this
project better and I greatly appreciate all of his time and support. Thanks also go to Dr.
Andrew Randall for agreeing to serve on my committee and for always being willing to
help me sort through microbiological issues. I also thank Dr. Ni-Bin Chang, who
enthusiastically joined my committee late in the process and was so willing to help and
positively contribute to this work. Thank you all so much.
I also acknowledge the Florida Center for Solid and Hazardous Waste and the
Environmental Research and Education foundation for funding this work. This work
would not have possible without your contributions.
Thanks also go to Jackie Ceather, who helped me tremendously with some of the
laboratory work. Her help and time were greatly appreciated. I would not have slept
during the past five years if it weren’t for her. Thanks also go to my fellow research
group colleagues, particularly those who spent so much time in the lab with me (Eyad,
Lucia and Andrea).
I also would like to extend thanks to my dear friends Sara and Bryan Stone. I
couldn’t have made it without all of your support. You guys helped to keep me somewhat
sane through this process and always reminded me why I was here.
Finally, I thank my family for their enduring love and support. My Mom always
taught me that if I worked hard and believed in myself, I could accomplish anything. And
she was right. Thanks for always being supportive. I also thank my Step-Dad for all of his
support and wisdom throughout the years. And, of course, I thank my little brothers,
Weber and Mattison, whom I cherish more than anything. I am finally graduating, guys!
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TABLE OF CONTENTS

LIST OF TABLES............................................................................................................xi
LIST OF FIGURES.........................................................................................................xii
CHAPTER 1 INTRODUCTION.......................................................................................1
Background Information..............................................................................................1
Research Objectives and Scope of Work....................................................................4
Dissertation Organization............................................................................................6
References......................................................................................................................7
CHAPTER 2 THE FATE OF NITROGEN IN BIOREACTOR LANDFILLS............11
Introduction.................................................................................................................11
Bioreactor Landfill Operation...................................................................................13
Anaerobic Bioreactor Landfills.................................................................................17
Aerobic Bioreactor Landfills....................................................................................19
Hybrid Bioreactor Landfills......................................................................................21
Facultative Bioreactor Landfills...............................................................................24
Ammonia-Nitrogen in Leachate................................................................................25
Nitrogen Transformation and Removal Processes..................................................27
Ammonification........................................................................................................30
Ammonium Flushing................................................................................................31
Ammonium Sorption................................................................................................32
Volatilization.............................................................................................................36
Nitrification...............................................................................................................38
Nitrification Case Studies in Landfills..................................................................43
Nitrification Kinetics............................................................................................45
Denitrification...........................................................................................................46
Heterotrophic Denitrification................................................................................47
Autotrophic Denitrification...................................................................................49
Denitrification Kinetics.........................................................................................51
ANAMMOX.............................................................................................................51
Dissimilatory Nitrate Reduction to Ammonium......................................................52
Simultaneous Nitrogen Removal Processes..............................................................55
Other Nitrate Processes.............................................................................................56
Future Research Directions.......................................................................................57
References....................................................................................................................58
CHAPTER 3 THE IMPACT OF WASTE ACCLIMATION ON IN-SITU AMMONIA
REMOVAL FROM BIOREACTOR LANDFILL LEACHATE....................................70
Introduction.................................................................................................................70
Materials and Methods...............................................................................................73
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Aerobic Reactor (Waste Acclimation Process) Design and Operation....................73
In-Situ Nitrification Microcosm Studies...................................................................75
Analytical Techniques..............................................................................................77
Results and Discussion................................................................................................79
Aerobic Reactor (Waste Acclimation Process).........................................................79
In-Situ Nitrification Microcosm Studies...................................................................83
Ammonia Sorption................................................................................................84
In-Situ Nitrification Processes..............................................................................85
Simultaneous Nitrogen Removal Processes..........................................................86
Ammonia Removal Kinetics.................................................................................90
Acclimated vs Unacclimated Processes............................................................93
Field-Scale Ammonia Removal Implications...................................................94
Nitrogen Mass Balances.......................................................................................95
Conclusions..................................................................................................................96
References....................................................................................................................97
CHAPTER 4 THE IMPACT OF GAS-PHASE OXYGEN AND TEMPERATURE ON
IN-SITU AMMONIA REMOVAL FROM BIOREACTOR LANDFILL LEACHATE
.........................................................................................................................................101
Introduction...............................................................................................................101
Experimental Materials and Methods....................................................................103
Microcosm Study Operation...................................................................................104
Analytical Techniques............................................................................................106
Results and Discussion..............................................................................................106
Nitrogen Removal Processes..................................................................................106
Ammonia-Nitrogen Removal Rates........................................................................113
Impact of oxygen and temperature on removal rates..........................................113
Combined effects on ammonia removal.............................................................122
References..................................................................................................................125
CHAPTER 5 ENGINEERING SIGNIFICANCE........................................................128
Introduction...............................................................................................................128
Model Description.....................................................................................................128
Simulation of Laboratory Experiments..................................................................135
Model Results............................................................................................................138
Optimizing Treatment Depth...................................................................................143
In-Situ Denitrification..............................................................................................145
Field Study Plans......................................................................................................146
Economic Analysis....................................................................................................149
In-Situ Treatment Economics.................................................................................149
Cost Comparison With Other Leachate Treatment Systems..................................153
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References..................................................................................................................156
CHAPTER 6 CONCLUSIONS AND RECOMMENDATIONS..................................159
Conclusions................................................................................................................159
Field-Scale Implementation Recommendations.....................................................161
APPENDIX A MATERIALS AND METHODS...........................................................163
Introduction...............................................................................................................164
Waste Acclimation Process......................................................................................164
Microcosm Studies....................................................................................................169
Failed Microcosm Designs.....................................................................................170
Chosen Microcosm Design.....................................................................................171
Microcosm Sampling Procedure.........................................................................172
Experiments Conducted......................................................................................173
Impact of Waste Acclimation Experiments....................................................173
Impact of Gas-Phase Oxygen and Temperature Experiments........................174
Analytical Techniques..............................................................................................177
pH............................................................................................................................177
Ammonia.................................................................................................................177
Anions (nitrate, nitrite, sulfate)...............................................................................179
Alkalinity................................................................................................................180
Gas-Phase Oxygen and Nitrogen............................................................................180
Gas-Phase Nitrous Oxide........................................................................................181
Chemical Oxygen Demand (COD).........................................................................181
Solid-Phase Organic Nitrogen................................................................................182
Volatile Solids.........................................................................................................183
Moisture Content....................................................................................................183
Gas Volume............................................................................................................183
Ammonia Gas.........................................................................................................184
References..................................................................................................................184
APPENDIX B WASTE ACCLIMATION PROCESS RESULTS................................185
Introduction...............................................................................................................186
Summary of Results..................................................................................................186
Waste Acclimation Process #1................................................................................186
Waste Acclimation Operation at 22oC................................................................186
Waste Acclimation Operation at 35oC................................................................189
Waste Acclimation Process #2................................................................................192
Waste Acclimation Operation at 45oC................................................................193
References..................................................................................................................198
APPENDIX C MODEL VALIDATION STATISTICS................................................199
Introduction...............................................................................................................200
Procedure...................................................................................................................200
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Discussion of Results.................................................................................................204
Data Sheets................................................................................................................206
References..................................................................................................................246
APPENDIX D CONFIDENCE INTERVAL DETERMINATION.............................247
Introduction...............................................................................................................248
Summary of Results..................................................................................................248
Case #1: Comparison Between Oxygen Levels at Constant Temperature Using the
Monod Model Without Temperature and pH Terms..............................................249
Case #2: Comparison Between Oxygen Levels at Constant Temperature Using the
Complete Monod Model (including temperature and pH terms)............................249
Case #3: Comparison Between Temperatures at Different Oxygen Levels Using the
Complete Monod Model (including temperature and pH terms)............................250
Discussion of Results.................................................................................................250
Data Sheets................................................................................................................252
Comparison Between Oxygen Levels at Constant Temperature Using the Monod
Model Without Temperature and pH Terms...........................................................252
Comparison Between Oxygen Levels at Constant Temperature Using the Complete
Monod Model (including temperature and pH terms)............................................256
Comparison Between Temperatures at Different Oxygen Levels Using the Complete
Monod Model (including temperature and pH terms)............................................260
APPENDIX E MODEL CODE.....................................................................................264
APPENDIX F PLOTS OF ALL MICROCSM DATA..................................................273
Microcosms at 22oC..................................................................................................274
Acclimated Waste...................................................................................................274
Microcosms at 22oC.................................................................................................290
Unacclimated Waste...............................................................................................290
Microcosms at 35oC..................................................................................................293
Microcosms at 45oC..................................................................................................309
APPENDIX G ECONOMIC CALCULATIONS..........................................................322
Air Flowrate Calculations........................................................................................323
Blower Power Requirement Calculations...............................................................326
Air Piping Calculations............................................................................................328
Leachate Injection Pump Calculations...................................................................329
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