Biochemical Methane Potential Estimation of Feed Mixtures Used for Dry Anaerobic Digestion

137 Pages·2013·2.85 MB·English

Biochemical Methane Potential Estimation of Feed Mixtures Used for
Dry Anaerobic Digestion

by

Siripong Manjanthrarat

A thesis submitted in partial fulfillment of the requirements for the
degree of Master of Engineering in
Environment Engineering and Management

Examination Committee: Prof. Chettiyappan Visvanathan (Chairperson)
Prof. Ajit P. Annachhatre
Dr. Anil Kumar Anal

Nationality: Thai
Previous Degree: B a c helor of Engineering in Civil Engineering
King Mongkut‟s University of Technology
North Bangkok
Bangkok, Thailand

Scholarship Donor: Royal Thai Government – AIT Fellowship

Asian Institute of Technology
School of Environment, Resources and Development
Thailand
May 2013
Acknowledgements

I would like to express my deepest gratitude and heartfelt thanks to my thesis advisor Prof.
C. Visvanathan, for his valuable guidance, support, time, enthusiasm, inspiration, great
efforts to explain thing clearly and simple and encouragement thought his research.

Special appreciation is also extended to Prof. Ajit P. Annachhatre and Dr. Anil Kumar
Anal as the thesis committee members, for their constructive criticisms, helpful suggestion
and valuable discussions. They have given time and much needed advice throughout the
research. Without their guidance and support, this work would not have been achieved.

I am grateful to Ms. Salaya P., Ms. Suchitra P., and all staff members in Environmental
Engineering and Management Program for their countless hours of discussion and sharing
of their idea and experience. Also I am very thankful to the technical staffs; Mr. Panupong
Boonyanuun, Ms. Orathai Klubbarnkoh and his team for their extensive assistance during
the conduct of this research as well all lab and office mates for their assistance and
refreshing conversation.

I would like to gratefully acknowledge to Royal Thai Government (RTG) for scholarships
for the Master study in AIT. Moreover, my deep gratitude goes to Pathum Thani Brewery
Company and Singha Corporation for anaerobic digestion seed sludge.

I am thankful to Prof. C. Visvanathan‟s research group for their support. Especially my
thanks go to Mr. P. Jacob and Mr. T. Rathnayake for their technical support and
encouragement to complete the research successfully.

In addition, my deep great gratitude also is extended to all my dear teachers, faculty
members and all staffs and technicians of Environmental Engineering and Management for
their help, technical and moral support and cooperation, which assisted me to complete this
thesis

I would like to express my deep thanks to my colleagues, Ms. Phontida, Mr. Supawat, Mr.
Phanwatt, Mr. Kiattisak, Mr. Duc, Mr. Ahmad, Ms. Pinchanok, Mr. Lalith, Ms. Kamala
and Ms. Tasawan for their generous support in technically as well as humanly during the
entire period of my study.

Finally, my achievement would never be possible unless there is hearty support from my
family. The deepest and sincere gratitude goes to my beloved parents, my younger sister
for their endless love, encouragement and understanding throughout the entire period of
my study.

ii
Abstract

The anaerobic digestion of substrate (distiller grain, swine manure and food waste) is a
process that has become a promising technology in waste management through the world.
Thus, the main goal of this thesis was to find better substrate, optimum I/S ratio and C/N
ratio for anaerobic digestion under continuous process. In addition, this research was tested
appropriate substrate, optimum I/S ratio and C/N ratio in anaerobic digestion process by
BMP test.

Biochemical methane potential assay were conducted on several representative substrate
components to determine the ultimate biodegradability and conversion efficiency. BMP
test was operated under mesophilic condition (37°C). Base on the result obtained that
swine manure is better substrate for this experiment because it can produce specific
methane production around 159.24 L/kg VS and present methane around 59.26%. The
result shows that the highest percent methane around 68.93% and biogas production
around 9357.67mL was observer at I/S 2. The highest specific methane production was I/S
3 around 843.71 L/kg VS. From result, swine manure C/N 30 has highest specific methane
production around 827.86 L/kg VS, highest percent of methane around 73.98% and highest
methane volume around 7813.03mL. It concludes that swine manure at I/S ratio 2 and C/N
ratio 30 is better ratio for mixture substrate in this experiment.

Reactor experiment was researched to find optimum I/S ratio and C/N ratio. Reactor
experiment was operated under mesophilic condition (37°C). Operation reactor has two
phases i.e. start-up phase and continuous phase. In final phase, experiment was conducted
for three different loading which operate 25 days in each loading. Base on the result
obtained that I/S ratio 2 can produce the methane yield around 405.29 L/kg VS and highest
percent methane around 59.44%. the highest volatile solid removal of 30.95% was
observer at I/S 2. C/N ratio variation was tested to research appropriate C/N ratio under
continuous process. This study found that as organic loading rate increased, the biogas
production increased. The methane yield of C/N 30 obtained was 259 L/kg VS, 473 L/kg
VS and 462 L/kg VS from OLR 2, 3.5 and 5 kg VS/m3.day. However, when loading was
increase to 5 kg VS/m3.day, the significant deterioration of biogas composition as well as
production was observed. The highest percent methane around 68.47 % at OLR 3.5 kg
VS/m3.day was observed at swine manure C/N ratio 30. The volatile solid removal of
24.49%, 22.05% and 18.81% were obtained during the 2, 3.5 and 5 kg VS/m3.day
respectively. These were observed at swine manure C/N ratio 30.

iii
Table of Contents

Chapter Title Page

Title Page i
Acknowledgements ii
Abstract iii
Table of Contents iv
List of Tables vi
List of Figures vii
List of Abbreviations viii

1 Introduction
1
1.1 Background of the Study 1
1.2 Objectives of the Study 2
1.3 Scope and Limitation of the Study 2

2 Literature Review 3
2.1 Introduction 3
2.2 Principles of BMP Test 5
2.3 General AD Process Description 12
2.4 Factor Affecting Operation of AD Process 19
2.5 Dry Anaerobic Digestion 24
2.6 Effect of Co-Digestion on Methane Yield Synergistic Substrate 25
Mixture
2.7 Current Status of AD Treatment Process 26
2.8 Other Techniques to Optimize Dry Anaerobic Digestion 26

3 Methodology 29
3.1 Introduction 29
3.2 Selection of Substrate/Feed Stock 30
3.3Slection of Seed Sludge/Inoculums 31
3.4 Phase 1: Biochemical Methane Potential (BMP) Test 31
3.5 Phase 2: Batch Test (Reactor Experiment) 33
3.6 Laboratory Analysis 35

4 Results and Discussions 38
4.1 Raw Material Preparation and Analysis 38
4.2 Biochemical Methane Potential (BMP) Test 40
4.3 Continuous Anaerobic Digestion Reactor by I/S Ratio Variation 53
4.4 Continuous Anaerobic Digestion Reactor by C/N Ratio Variation 56
4.5 Overall Experiment Performance 63

5 Conclusions and Recommendations 66
5.1 Conclusions 66
5.2 Recommendations for Further Study 67

References 68
iv
Appendix A 76
Appendix B 77
Appendix C 79
Appendix D 91
Appendix E 96
Appendix F 98
Appendix G 104
Appendix H 108
Appendix I 110
Appendix J 115
Appendix K 121

v
List of Table

Table Title Page

2.1 Characteristic of Distiller Grains 7
2.2 Comparison BMP Test and CH Yield 10
4
2.3 Mesophiclic and Themophilic Anaerobic Digestion 18
2.4 Inhibition of Biomethanization 21
2.5 Typical C/N Ratio for Various Materials 22
2.6 Comparison of Dry and Wet Anaerobic Digestion Technology 24
3.1 Analytical Method Parameters for Substrate 30
3.2 Condition in Each Reactor for BMP Test 33
4.1 Characteristic of Raw Material and Inoculums 39
4.2 Mixture Substrate of BMP Test (Distiller Grain with Swine 40
Manure) to Research Optimum C/N Ratio
4.3 Mixture Substrate of BMP Test (Distiller grain with Food waste) to 41
Research Optimum C/N Ratio
4.4 Characteristic of Substrate for BMP Test 41
4.5 Loading Schemes for Continuous Operation (Substrate C:N 25) 57
4.6 Loading Schemes for Continuous Operation (Substrate C:N 30) 57
4.7 Loading Schemes for Continuous Operation (Substrate C:N 35) 57
4.8 Characteristic of substrate for reactor experiment 58

vi
List of Figure

Figure Title Page

2.1 Trend of low solid and high solid anaerobic digestion plant in Europe 4
2.2 A complex diagram for anaerobic digestion considering five 15
simultaneous process
2.3 Classification of anaerobic digestion by operational criteria 17
3.1 Research methodology 29
3.2 Modified Duran bottle 1000mL 32
3.3 BMP test procedure 32
3.4 Reactor design 34
3.5 Top view of reactor (left) and the bottom view of batch reactor (right) 34
3.6 Batch test procedure 35
4.1 Cumulative biogas production of each substrate 42
4.2 Trend of biogas composition of each substrate 42
4.3 Cumulative biogas production of each I/S ratio 43
4.4 Trend of biogas composition of each I/S ratio 44
4.5 Cumulative biogas production of substrate in each C/N ratio 45
4.6 Trend of biogas composition of substrate in each C/N ratio 45
4.7 VS degradation for I/S various I/S ratio from BMP test 46
4.8 Profile total organic carbon for various I/S ratio from BMP test 46
4.9 Profile ammonium for various I/S ratio from BMP test 47
4.10 Profile VFA/Alkalinity for various I/S ratio from BMP test 47
4.11 VS degradation for compare substrate from BMP test 48
4.12 Profile total organic carbon for compare substrate from BMP test 48
4.13 Profile ammonium for compare substrate from BMP test 49
4.14 Profile VFA/Alkalinity of comparision substrate from BMP test 49
4.15 VS degradation for I/S various C/N ratio from BMP test 50
4.16 Profile total organic carbon for various C/N ratio from BMP test 50
4.17 Profile ammonium for various C/N ratio from BMP test 51
4.18 Profile VFA/Alkalinity for various C/N ratio from BMP test 51
4.19 Daily biogas production during start-up of each reactor 52
4.20 Cumulative biogas production during start-up of each reactor 53
4.21 Trend of biogas composition of each reactor during reactor start-up 53
4.22 VS degradation for various I/S ratio 54
4.23 Trend of TOC during start-up & continuous phase 54
4.24 Trend of total nitrogen during acclimatization & operating 55
4.25 Trend of ammonium during acclimatization & operating 55
4.26 Trend of VFA/Alkalinity ratios during acclimatization & continuous 56
operating
4.27 Daily biogas production during start-up & Loading rate 1, 2 and 3 59
4.28 Cumulative biogas production during start-up & Loading rate 1, 2 and 3 59
4.29 Trend of biogas composition during start-up & Loading rate 1, 2 and 3 60
vii
4.30 VS degradation for various organic loading rates 61
4.31 Trend of TOC during start-up & Loading rate 1, 2 and 3 61
4.32 Trend of total nitrogen during start-up & continuous phase operation 62
4.33 Trend of NH -N during start-up & continuous phase operation 62
4
4.34 Trend of VFA/Alkalinity ratios during start-up & continuous phase 63
operation
4.35 Profile of specific methane production of BMP test 63
4.36 Methane yield of various I/S ratio 64
4.37 Profile of methane yield for various organic loading rates condition 64

viii
List of Abbreviations

AD Anaerobic Digestion
ATA Anaerobic Toxicity Assay
BMP Biochemical Methane Potential
BVS Biodegradable Volatile Solid
C/N Carbon to Nitrogen ratio
COD Chemical Oxygen Demand
CSTR Continuous Stirred Tank Reactor
DAD Dry Anaerobic Digestion
F/M Food to Microorganism
HRT Hydraulic Retention Time
HS High Solids
HS-OFMSW Hand Sorted Organic Fraction of Municipal Solid Waste
I/S Inoculums to Substrate
LS Low Solids
MSW Municipal Solid Waste
OFMSW Organic Fraction of Municipal Solid Waste
OLR Organic Loading Rate
RT Retention Time
RVS Refractory Volatile Solids
S/I Substrate to Inoculums
SRT Solid Retention Time
SS-OFMSW Source-Sorted Organic Fraction of Municipal Solid Waste
TAN Total Ammonia Nitrogen
TOC Total Organic Carbon
TS Total Solid
TVS Total Volatile Solids
UASB Up-flow Anaerobic Sludge Blanket
VS Volatile Solid
VSS Volatile Suspended Solid
WAD Wet Anaerobic Digestion
ix
Chapter 1

Introduction

1.1Background of the Study

Anaerobic digestion is biological treatment process that uses microorganism to convert the
complex organic matters into simple and stable end products in the absence of oxygen.
During anaerobic digestion, biogas is produced as end product of microbial decomposition.
The anaerobic digestion can be divided into three types based on solid content of
feedstock. There are low-solid digestion [< 16% total solid (TS)], semi-solid digestion [16-
21% TS] and high-solid digestion or dry anaerobic digestion [22-40% TS]. Dry anaerobic
digestion has many advantage over wet digestion [<22% TS] (Ward et al., 2008). It likes
reduction of reactor volume and wastewater product for example. Also it needs less
dilution water than wet digestion. This method was also successful in low-solid and semi-
solid conditions, (Hennrenklage and Stegmann, 2005). In addition, it produces a fertilizer
that is easier to transport. Thus, in recent years development of dry anaerobic digestion was
been growing worldwide because of the increasing request for renewable energy
production. Anaerobic digestion is an engineered methanogenic decomposition of organic
matter in the absence of free oxygen and has presences of different anaerobic
microorganisms. The anaerobic digestions for waste treatment have significant benefits
that include both energy production and energy conservation. The production of biogas
from solid waste materials by using anaerobic digestion is a sustainable technology for
renewable energy source. In the early days, application of anaerobic digestion was for the
treatment of domestic and animal waste. Presently, the process has been widely used for
treatment of municipal sludge and industrial waste in developed countries. Due to
threatening on solid waste management for final disposal, municipalities are looking for
better solution and many research works are going to anaerobic digestion for its stable
performance.

Due to the increasing in application of anaerobic digestion, the BMP test was developed to
determine the ultimate methane yield of a given substrates and to monitor anaerobic
toxicity. Methane yield of a variety of biomass was determined using a modified method of
Owen et al., (1979), which is a valuable, quick and inexpensive method. The application of
anaerobic digestion technology is growing worldwide because of its economic and
environmental benefits. As a consequence, the number of studies and research activities on
determination of the biogas potential of solid organic substrates has been increasing.
Therefore, it is important to define a protocol for the determination of the ultimate methane
potential for a given solid substrates (Angelidaki . et al., 2009).

BMP test was successfully conducted in low-solid and semi-solid conditions by many
authors such as Owens and Chynoweth, (1993), Angelidaki and Sander, (2004) and Hasen
et al., (2004). However, there is insufficient technical information on BMP test in dry
anaerobic digestion condition. Originally BMP test method was used to analyze
biodegradability of organic material in wet condition. Due to the above reasons, there is a
need to develop a BMP test for dry anaerobic condition.

The biogas production is very attractive in dry anaerobic digestion. However, the dry
anaerobic digestion is more sensitive to inhibitions due to high concentration of VFA and
ammonia than wet digestion that can affect the operation system. The operating parameters
1