Anaerobic Digestion of Poultry Manure

144 Pages·2016·10.04 MB·English

Anaerobic Digestion of Poultry Manure: Implementation of Ammonia
Control to Optimize Biogas Yield

by

Cameron Farrow

A Thesis
presented to
The University of Guelph

In partial fulfilment of requirements
for the degree of
Doctor of Philosophy
in
Engineering

Guelph, Ontario, Canada

© Cameron Farrow, May 2016
ABSTRACT

ANAEROBIC DIGESTION OF POULTRY MANURE: IMPLEMENTATION OF
AMMONIA CONTROL TO OPTIMIZE BIOGAS YIELD

Cameron Farrow Advisors: Edward McBean, Anna Crolla, Chris Kinsley
University of Guelph, 2016

Anaerobic digestion of poultry manure has been historically challenging, and
infrequently implemented on a full scale, due to the high total solids (TS) and high
ammonia content of the substrate. Conventional digestion processes require extensive
substrate dilution in order to employ liquid-phase pumping systems and reduce the risk of
ammonia accumulation. The necessary substrate dilutions result in an economically
infeasible process. Anaerobic leaching bed reactors (ALBRs), coupled with a strategy for
ammonia removal, provide a solution to both issues.

ALBRs are utilized to maintain digester homogeneity without an active mixing regime.
Struvite precipitation is employed concurrently with digestion to reduce total ammoniacal
nitrogen (TAN) and prevent inhibition of methanogenic archaea. Nutrient distribution is
achieved by recirculation of the percolate through the substrate, enabling the utilization
of high solids feedstocks. Partitioning leachate from the bulk substrate allows ammonia
removal methodologies to be employed without disturbing anaerobic archaea.

Investigations reported herein characterize the influence of moisture content, TAN and
temperature on biogas yield during poultry manure digestion. High solids digestion is
shown to be most efficient in mesophilic temperature ranges with influent total solids
(TS) between 15% and 25%. Digestion at thermophilic temperatures demonstrates
increased ammonia inhibition, in contrast to mesophilic digestion. Co-digestion of
poultry manure with grease and corn silage demonstrate increased biogas yields of 22%
and 44%, respectively, in comparison to digestion of poultry manure alone.

The impact of phosphate and magnesium additives, pH, temperature and the N:Mg:P
molar ratio on struvite precipitation efficacy are quantified. Magnesium chloride
(MgCl ·6H O) and monopotassium phosphate (KH PO ) are shown to be the most
2 2 2 4
efficient combination of additives for TAN reduction of poultry manure leachate under
neutral reaction conditions. Precipitation is shown to progress efficiently at a pH of seven,
in contrast to the commonly reported optimum of nine. Thus allowing leachate treatment
without disturbing the microbial consortium.

Results reported herein evidence an increase in biogas yield of 30% during batch
digestion trials and an increase of 235% during semi-continuous trials, when employing
struvite precipitation methodologies. Methane content of the biogas is also shown to
increase significantly (p<0.05), when employing struvite precipitation.
ACKNOWLEDGEMENTS

This dissertation would not have been possible without the contribution of countless
individuals, too many to mention by name herein. First and foremost, I would like to thank
my family:

• My mom, Barbara Hardy, for the continuous support in all aspects of my academic
career. I would not be where I am today without her guidance, advice and
encouragement.

• My brother, Trevor Farrow, for always being supportive of my goals, even when
they are not aligned with his (and they rarely are).

• My dad, Rob Farrow, for providing assistance with all the technical problems I
encountered; it’s always good to have an experienced engineer on hand.

• My partner, Emily Wilkins, for being unfailingly supportive and making numerous
sacrifices for my continued education.

I would also to like to thank my advisory committee: Ed McBean, Anna Crolla and Chris
Kinsley. All of whom provided direction and leadership throughout my doctoral studies.
Their patience, motivation, knowledge and enthusiasm made this research possible.

Additionally, I would like to express my appreciation to the Ontario Ministry of
Agriculture and Food: Alternative Fuels Program, as well as Natural Resources Canada for
the funding that enabled this research.

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TABLE OF CONTENTS
1.0 Introduction ................................................................................................................. 1
1.1 Objectives and Research Focus ........................................................................................... 2
1.2 Thesis Organization ............................................................................................................. 4
2.0 Background .................................................................................................................. 5
2.1 Renewable Energy ................................................................................................................ 5
2.2 First and Second Generation Biofuels ................................................................................ 5
2.3 Encouraging the Use of Renewable Energy Technologies: Feed-In-Tariffs (FITs) ....... 6
2.4 Current State of Farm-Scale Anaerobic Digestion ........................................................... 7
2.4.1 Economics of AD in Ontario, Canada ............................................................................ 8
2.4.2 USEPA AgSTAR Program (AD in the United States of America) ................................ 9
2.5 Anaerobic Digestion: The Fundamentals ........................................................................... 9
2.6 Utilizing Biogas as an Energy Source ............................................................................... 12
2.7 Anaerobic Digestion Technologies .................................................................................... 12
2.7.1 Upflow Anaerobic Sludge Blanket (UASB) ................................................................. 13
2.7.2 Anaerobic Filters/ Packed-Bed Reactors ...................................................................... 13
2.7.3 Anaerobic Membrane Bioreactors (AnMBRs) ............................................................. 14
2.7.4 Continuously Stirred Tank Reactors (CSTRs) .............................................................. 14
2.7.5 Plug Flow Reactors/ Continuous Tubular Reactor (CTR) ............................................ 15
2.7.6 Anaerobic Leaching Bed Reactors (ALBRs) ................................................................ 15
2.8 Operating Parameters ........................................................................................................ 17
2.8.1 Continuous vs. Batch Operation ................................................................................... 17
2.8.2 Residence Time/ Hydraulic Retention Time (HRT) ..................................................... 18
2.8.3 Attached vs. Suspended Growth ................................................................................... 18
2.8.4 Temperature .................................................................................................................. 18
2.8.5 Waste:Inoculum Ratio .................................................................................................. 20
2.8.6 Digester Scale ............................................................................................................... 20
2.9 Co-digestion ........................................................................................................................ 21
2.10 Livestock Manure: Environmental Impacts .................................................................. 23
2.11 Poultry Manure Characterization .................................................................................. 24
2.12 Current State of Poultry Manure Management ............................................................ 26
2.13 Barriers to Poultry Manure Digestion ............................................................................ 26
2.14 Dry Anaerobic Digestion .................................................................................................. 28
2.15 Fertilization Capacity of Digestate ................................................................................. 30
2.16 Poultry Manure Digestion: A review of current literature .......................................... 31
2.17 Total Ammoniacal Nitrogen (TAN): Inhibition of AD ................................................. 34
2.18 Methods of Ammonia Control ......................................................................................... 36
2.18.1 Dilution ....................................................................................................................... 36
2.18.2 Co-digestion ................................................................................................................ 37
2.18.3 Ammonia Acclimation ................................................................................................ 37
2.18.4 Ammonia Stripping ..................................................................................................... 38
2.18.5 Anaerobic Ammonium Oxidation (ANAMMOX) ..................................................... 39
2.18.6 Struvite Precipitation ................................................................................................... 40
2.19 Research Gaps and Original Contribution .................................................................... 43
3.0 Methodology .............................................................................................................. 44
3.1 Biochemical Methane Potential (BMP) ............................................................................ 44
3.2 Anaerobic Leaching Bed Reactors (ALBRs) ................................................................... 45
3.3 Sample Collection ............................................................................................................... 46
3.4 Statistical Analysis .............................................................................................................. 46
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3.4.1 Significance Testing ...................................................................................................... 46
3.4.2 Central Composite Designs: Response Surface Methodology ..................................... 47
3.4.3 Analysis of Variation (ANOVA) .................................................................................. 48
3.5 Struvite Precipitation ......................................................................................................... 49
3.6 Parameters and Analytical Methods ................................................................................ 50
3.6.1 Total Solids (TS) and Volatile Solids (VS) .................................................................. 50
3.6.2 Chemical Oxygen Demand (COD) ............................................................................... 51
3.6.3 pH and Alkalinity .......................................................................................................... 52
3.6.4 Total Ammonia Nitrogen (TAN) .................................................................................. 53
3.6.5 Total Kjeldahl Nitrogen (TKN) ................................................................................... 54
3.6.6 Total Phosphorous (TP) and Ortho-phosphate (O-PO ) ............................................... 54
4
3.6.7 Carbon:Nitrogen Ratio (C:N) ....................................................................................... 54
4.0 Influence of Temperature and Ammonia on the High Solids Co-Digestion of
Poultry Manure ............................................................................................................... 56
4.0.1 Abstract ......................................................................................................................... 57
4.0.2 Keywords ...................................................................................................................... 57
4.1 Introduction ........................................................................................................................ 58
4.2 Materials and Methods ...................................................................................................... 62
4.2.1 Effects of Moisture Content on Biogas Yield ............................................................... 63
4.2.2 Effects of Temperature and Total Ammoniacal Nitrogen on Biogas Yield – With and
Without the Use of Co-substrates .......................................................................................... 63
4.2.3 Statistical Analysis ........................................................................................................ 64
4.3 Results and Discussion ....................................................................................................... 66
4.3.1 Characteristics of Input Materials ................................................................................. 66
4.3.2 Effects of Moisture Content on Biogas Yield ............................................................... 67
4.3.3 Effects of Temperature and Total Ammoniacal Nitrogen on Biogas Yield from the
Digestion of Poultry Manure Alone ....................................................................................... 70
4.3.4 Effects of Temperature and Ammoniacal Nitrogen on Biogas Yield from the Co-
digestion of Poultry Manure with Corn Silage and Waste Grease ........................................ 71
4.4 Conclusions ......................................................................................................................... 76
5.0 Ammonia removal from poultry manure leachate via struvite precipitation: A
strategy for more efficient anaerobic digestion ............................................................ 78
5.0.1 Abstract ......................................................................................................................... 79
5.0.2 Keywords ...................................................................................................................... 79
5.1 Introduction ........................................................................................................................ 80
5.2 Materials and Methods ...................................................................................................... 84
5.3 Results and Discussion ....................................................................................................... 87
5.3.1 Identification of Optimum Magnesium and Phosphate Amendments under Neutral
Reaction Conditions ............................................................................................................... 87
5.3.2 Impact of pH and Temperature on Efficiency of Struvite Precipitation ....................... 88
5.3.3 Impact of Molar Ratio on Precipitation Efficiency ....................................................... 92
5.3.4 Composition of Precipitates .......................................................................................... 93
5.4 Conclusions ......................................................................................................................... 96
6.0 Anaerobic digestion of poultry manure: process optimization employing struvite
precipitation and novel digestion technologies ............................................................. 97
6.0.1 Abstract ......................................................................................................................... 98
6.0.2 Keywords ...................................................................................................................... 98
6.1 Introduction ........................................................................................................................ 99
6.2 Materials & Methods ....................................................................................................... 103
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6.2.1 Batch Digestion ........................................................................................................... 105
6.2.2 Semi-Continuous Digestion ........................................................................................ 106
6.2.3 Struvite Precipitation .................................................................................................. 107
6.2.4 Statistical Analysis ...................................................................................................... 107
6.3 Results and Discussion ..................................................................................................... 108
6.3.1 Batch Digestion ........................................................................................................... 108
6.3.2 Semi-Continuous Digestion ........................................................................................ 113
6.3.3 Design Feasibility ....................................................................................................... 122
6.4 Conclusions ....................................................................................................................... 123
7.0 Conclusions and Impact ......................................................................................... 124
8.0 References ................................................................................................................ 127
Appendix A – Correlation of Experimental and Predicted Biogas Yields .............. 133

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LIST OF TABLES

Table 2-1: Second generation biofuel sources 6
Table 2-2: Current FIT prices for biogas production facilities 8
Table 2-3: Current FIT program participation price adjustments 9
Table 2-4: Typical hydraulic retention times (HRT) for various animal manures 18
Table 2-5: Characteristics of solid wastes produced in poultry farming operations 25
Table 2-6: Operational and performance review of poultry manure digestion trials 32
Table 2-7: Impact of temperature and pH on the fraction (%) of free/unionized ammonia 35
Table 3-1: Box-Wilson central composite design circumscribed for two factors 48
Table 4-1: Circumscribed central composite design parameters: coded and natural design factors 64
Table 4-2: Influent substrate parameters 66
Table 4-3: C/N ratios of influent substrates. 66
Table 4-4: Digestate parameters: BMP moisture variation trials 69
Table 4-5: Parameters of BMP co-digestion trials 75
Table 5-1: Characterization of filtered leachate 87
Table 5-2: Struvite precipitation of poultry manure leachate employing various chemical amendments 88
Table 5-3: Struvite precipitation of poultry manure leachate at various pHs 89
Table 5-4: Struvite precipitation of poultry manure leachate employing various molar ratios of additives 92
Table 5-5: Characterization of precipitate obtained during struvite precipitation 95
Table 6-1: Influent substrate parameters 108
Table 6-2: Methane content (CH ) of biogas obtained under different organic loading rates (OLRs). 122
4

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LIST OF FIGURES

Figure 2-1: Distribution of farm based biogas plants in North America and the European Union 7
Figure 2-2: Fundamental anaerobic digestion processes 10
Figure 2-3: Anaerobic leaching bed reactor (ALBR) 16
Figure 3-1: Biochemical methane potential (BMP) vessel schematic 45
Figure 3-2: Struvite precipitate 50
Figure 4-1: Cumulative biogas production (L/kgVSin) vs. digestion time (days) 68
Figure 4-2: Biogas yield (L/kgVSin) vs. temperature (°C) and total ammoniacal nitrogen (TAN) (mg/L) 72
Figure 4-3: Biogas & methane yield (L/kgVSin) vs. substrate 74
Figure 5-1: Total ammoniacal nitrogen (TAN) and chemical oxygen demand (COD) reduction vs. pH 89
Figure 5-2: Mass of precipitate vs. initial total ammoniacal nitrogen (TAN) (mg/L) and pH. 91
Figure 5-3: Residual concentrations of total ammoniacal nitrogen (TAN) and orthophosphate. 92
Figure 5-4: X-ray powder diffraction (XRD) analysis of precipitate sample and struvite reference 94
Figure 6-1: Anaerobic leaching bed reactor (ALBR) 105
Figure 6-2: Cumulative biogas yield (L/kgVS ) vs. digestion time (days): batch digestion 109
in
Figure 6-3: Parameters of leachate and bed samples: batch digestion 111
Figure 6-4: Biogas yield of struvite and control trials at an OLRs of 1.5, 3.0 and 4.5 kg VS/m3Ÿday 114
Figure 6-5: Parameters of leachate: semi-continuous digestion: OLR 1.5 kg VS/m3Ÿday 116
Figure 6-6: Parameters of leachate: semi-continuous digestion: OLR 3.0 kg VS/m3Ÿday 119
Figure 6-7: Parameters of leachate: semi-continuous digestion: OLR 4.5 kg VS/m3Ÿday 121
Figure A-1: Experimental vs. predicted biogas yield: poultry manure 133
Figure A-2: Magnitude of residuals: poultry manure 133
Figure A-3: Experimental vs. predicted biogas yield: poultry manure and corn silage 134
Figure A-4: Magnitude of residuals: poultry manure and corn silage 134
Figure A-5: Experimental vs. predicted biogas yield: poultry manure and waste grease 135
Figure A-6: Magnitude of residuals: poultry manure and waste grease 135

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ABBREVIATIONS

AD: Anaerobic digestion
ALBR: Anaerobic leaching bed reactor
AnMBR: Anaerobic membrane bioreactor
ANNAMOX: Aerobic ammonium oxidation
ANOVA: Analysis of variation
BMP: Biochemical methane potential
C:N: Carbon to nitrogen ratio
CAFB: Cochran’s approximation to the Behren’s Fisher t-Test
CHP: Combined heat and power
CI: Confidence interval
COD (sCOD): Chemical oxygen demand (soluble chemical oxygen demand)
CSTR: Continuously stirred tank reactor
CTR: Continuous tubular reactor
FIT: Feed-in tariff
GC: Gas chromatograph
GHG: Greenhouse gas
HRT: Hydraulic retention time
HSAD: High solids anaerobic digestion
IA: Intermediate alkalinity
IPCC: Intergovernmental Panel on Climate Change
LSAT: Land surface air temperature
MAP: Magnesium ammonium phosphate hexahydrate, struvite
MSW: Municipal solid waste
O-PO : Ortho-phosphate
4
OMAFRA: Ontario Ministry of Agriculture, Food and Rural Affairs
PA: Partial alkalinity
REN21: Renewable Energy Policy Network for the 21st Century
SSAD: Solid-state anaerobic digestion
STP: Standard temperature and pressure (273K, 100 KPa)
TA: Total alkalinity
TAN: Total ammoniacal nitrogen
TCD: Thermal conductivity detector
TKN: Total Kjeldahl nitrogen
TN: Total nitrogen
TP: Total phosphorous
TS: Total solids
UASB: Upflow anaerobic sludge blanket
USEPA: United States Environmental Protection Agency
VS: Volatile solids
WWTP: Wastewater treatment plant
XRD: X-ray powder diffraction
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1.0 Introduction
The human population has grown rapidly in the latter half of the 21st century, from
approximately 3 billion in 1960 to over 7 billion in 2015 (World Population Clock, 2015).
As population rapidly increases, so does energy demand. Currently, approximately 81%
of global energy demand is met with fossil fuels (REN21, 2015). Projections indicate that
global energy demand will continue to increase by approximately 2.2% per year between
2015 and 2035 (IEA, 2010). Employing traditional fossil fuel-based energy solutions to
meet this ever-growing demand will result in continued escalation of greenhouse gas
(GHG) emissions and global warming.

The Intergovernmental Panel on Climate Change (IPCC) has reported an increase in
global Land Surface Air Temperatures (LSAT) of approximately 0.1°C per decade over
the last century, and 0.2°C per decade since 1950 (Jones et al., 2012; Lawrimore et al.,
2011; Hansen et al., 2010). In Canada, Vincent et al. (2012) reported an average increase
of 1.5°C in annual mean temperature from 1950 to 2010. The atmospheric methane (CH )
4
concentration is currently increasing at a rate above 1% per year and has more than
doubled in the last 200 years (Safley et al., 1992). Methane constitutes approximately
20% of global warming due to the greenhouse gas effect (Safley et al., 1992).

Renewable, carbon-neutral energy production will decrease societal reliance on fossil
fuels and provide an alternative solution to meet the requirements of increasing global
energy demand. In the near future, renewable energy technologies are expected to
1