Anaerobic Digestion Microbiome Study

METAGENOMICS • DATA SCIENCE • BIOBANKING

2017 Performance Comparison of Biogas Anaerobic Digesters Report

2017 comparative study of biogas anaerobic digesters based on DNA sequencing of samples collected. Includes the DNA sequencing results of each sample, grouped and analyzed for each digester included in the study, and each digester type. Survey data is included to augment DNA testing. Includes pdf version available for immediate download after purchase (64 pages).

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Executive Summary

Performance Comparison of Anaerobic Digesters

Anaerobic digesters are employed in wastewater, landfill and livestock operations worldwide to create renewable energy. Improving biogas production in a one-million gallon reactor by 5-10% can offset up to $200,000 annually in power costs when used for onsite power (Ling, A. 2020).

This study used 60 samples from 21 digesters representing a variety of industries, feedstocks, reactor design, and operational conditions. Microbial community data and digester operation and outcome data were used to understand the relationships between operation, community members, and outcomes.

Each digester and site studies had specific digester microbiomes that were more similar to each other than to other digesters. This suggests that microbial community results are site-specific. The community composition associated with optimum results will vary between sites. Despite this limitation, some general community trends were observed across the samples studied, and these may be used to make general conclusions about digester operation and community structure. Briefly,

Higher relative abundances of total archaea, pseudomonads, and commomonads correlated to higher percent CH4 in produced gas
Thermophilic conditions and blanket-type reactors correlated to higher archaea relative abundances and higher percent CH4 in produced gas
COD removal correlated directly to CH4 production
Higher VFA to alkalinity ratios and lower pH in the ranges observed (pH 6.7 to 7.8 and VFA : alkalinity 0.04-0.24) correlated to higher archaea relative abundances
Digesters treating municipal wastes harbored more diverse and even communities than digesters treating only industrial wastes, possibly due to the regular addition of waste activated sludge.

Based on these results, several key microbial indicators were identified for use in tracking changes in a digester microbiome:

Community diversity (number of microbe types)
Community evenness (how evenly microbe types are distributed)
Total relative abundance of:
- Total methanogens (total archaea)
- Key methanogen groups: Methanobacterium spp., Methanosaeta spp., Methanothermobacter spp.

This report also proposes several key performance indices (KPIs) based on these indicators to help operators use microbial community analysis to inform and improve system operation.

Executive Summary 1
1.0 Introduction 3
Study Overview 3
Study Goals 3
Overview of Methods Used in this Study 3
Description of Samples Included in this Study 4
Study Results and Discussion 4
General Community Trends 4
Microbiome Trends by Industry Key Microbial Players 7
Hydrolytic Bacteria 11
Acidogenic and Acetogenic Bacteria 11
Methanogenic Archaea 11
Others 11
Summary of Key Microbial Groups 12
Linking Microbiome to Design and Operational Conditions 14
Reactor SRT 14
Reactor Mixing Regime 14
Temperature (mesophilic, thermophilic) 14
COD Removal 15
VFAs and VFA:alkalinity ratio 15
Nutrient concentrations in digester (ammonia, ortho-P) 16
Feedstock (primary sludge, secondary sludge, agricultural solids, high-strength liquids) 16
Chemical additives (micronutrients, iron, P) 16
pH 16
Relating Archaea Relative Abundance to Operating Parameters 16
Linking Microbiome to Digester Outcomes 17
Methane production 18
Biogas composition 18
Stability and resilience (reduce probability of upset) 18
Other issues (scum, crust, foaming) 18
Implications for Digester Performance and Operation 19
Approach to Problem Solving 19
Bio-Methane Production 19
Reactor Stability and Resilience 19
Odor Production 20
Example Dashboard 20

List of Tables

Table 1 Summary of microbial groups observed in this study 9

Table 2 Summary of microbial member differences between reactor types 10

List of Figures

Figure 1 Visualization of microbial community similarities with each digester indicated (non-metric multidimensional scaling) 4

Figure 2 Visualization of microbial community similarities with municipal and industrial indicated (non-metric multidimensional scaling) 5

Figure 3 Diversity and evenness for municipal and industrial samples 6

Figure 4 Summary of microbial community composition 7

Figure 5 Visualization of microbial community similarities with mesophilic versus thermophilic reactors indicated and methanogen groups shown in blue (non-metric multidimensional scaling) 11

Figure 6 Predicted versus actual percent archaeal abundance 13

Figure 7 Digester operations and performance as related to microbiome and KPIs 15

Figure 8 Example Microbe Detectives Digester Dashboard 16

List of Appendices, Attachments, or Exhibits

Appendix A Study Methods

Appendix B Additional Figures and Correlations

Key findings presented at the Microbiome Water Summit

The Microbiome Water Summit was held on September 29th 2017 at the Shedd Aquarium in Chicago, Illinois. The summit featured leaders in this ground-breaking field of work. View key findngs of the study, presented by Dr. Alison Ling in the Summit video below.

“With specialized DNA sequencing that is being applied in these studies, the resource recovery industry finally has the opportunity to measure the microbiology much more comprehensively than what has been previously possible. The studies will help the industry interpret results and use this new insight to optimize systems. I believe this will be a game-changer for the industry.” –Jeremy Cramer, Sr Process Eng., Donohue & Associates

Biogas Study: Summary & Key Findings (60 minutes) by Dr. Alison Ling, Barr Engineering
Panel Moderator: Jeremy Cramer, Senior Process Specialist, Donohue & Associates
Autumn Fisher, Superintendent, City of Fond du Lac
Chris Lefebvre, Wastewater Superintendent, Stevens Point, Wisconsin
Nick Menninga, General Manager, Downers Grove Sanitary District
Kamlesh Patel, Senior Environmental Research Scientist, MWRD of Greater Chicago

Technical and Operational Advisory Group

Dr. Ling served as the principal author of this report. She is an environmental engineer with Barr Engineering Company in Minneapolis, MN. At Barr, she is engaged in front-end design and troubleshooting for water and wastewater treatment projects. Read more...

Her work includes process modeling, bench testing, and technical advising for clients in the power, mining, food and beverage, and municipal sectors. Ali completed her PhD at the University of Colorado at Boulder, where she split her time between the Environmental Engineering and Molecular Biology departments, and was co-advised by Norm Pace, an early pioneer in the field of 16S community analysis. For her PhD work, she analyzed microbial communities associated with concrete corrosion in wastewater collection systems and characterized correlations between microbial community trends and environmental metadata.

Dr. Trevor Ghylin is a professional water process engineer and has more than a decade of experience working for CH2M, the leading consulting firm in the water industry and also a senior process engineer for Xylem, a multi-billion dollar pure play water technology company. Read more...

Dr. Ghylin is passionate about harnessing innovation to utilize and protect water and energy resources and the environment. Dr. Ghylin is a licensed Professional Engineer and holds a Class IV wastewater treatment operators license in the state of Wisconsin. He has a B.S. degree from the University of North Dakota – Grand Forks in Civil Engineering and a Ph.D. degree from the University of Wisconsin – Madison in Civil and Environmental Engineering. Dr. Ghylin is very active in professional societies including the Water Environment Federation (Technical Committee for CSWEA Annual Conference) and Engineers without Borders (Marquette University Mentor). He has also spoken at Regional and National Conferences (CSWEA Annual Seminar, Madison, WI; WEFTEC, Chicago). He has a breadth of experience in environmental projects including greenhouse gas analyses, sustainability assessments, PCB cleanup in rivers as well as drinking water treatment and contaminated site remediation. Additionally, he has gained a deep understanding of environmental protection and water issues by working on numerous wastewater planning and design projects.

Dr. V. P. Tale has been working in the field of anaerobic digestion technology since year 2004 and his work in this field has been published through several peer reviewed journal articles, conference proceedings and provisional patent applications. Read more...

He started his professional career by designing full-scale Ananerobic Wastewater treatment plants in India for Jain Irrigation Systems Ltd. A continued interest in the Anaerobic Digestion technology brought him to United States of America in pursuit of doctoral studies. He obtained his PHD from Marquette University located in Milwaukee, WI where he had a chance to work with world renowned experts in the field of Anaerobic Digestion technology. During his PHD, Dr. Tale studied microbial populations in various anaerobic digesters using advance molecular techniques and established the first anaerobic community structure-function model which earned him the best student poster award at the American Society of Microbiology’s annual general meeting. After working with Novozymes North America Inc. as a Senior Scientist for nearly five years, today Dr. Tale works with River Bend Labs (RBL) headquartered in St. Charles, MO. Dr. Tale continues to provide his expertise to RBL’s Anaerobic waste and wastewater treatment clients. He and RBL are very passionate about implementing the advance molecular biology toolbox for solving operational problems of their clients and optimizing their anaerobic reactors.

Dr. Leon Downing is a senior technologist with CH2M and serves as the East Region Technology Lead. A graduate of the University of Wisconsin-Platteville, Leon then received his M.S. and PhD from the University of Notre Dame, focusing on process modeling and energy efficient biological nutrient removal. Read more...

Over the past decade, Dr. Downing has focused on the application of process modeling, innovative technologies, and operational strategies within the wastewater treatment field. Leon has most recently been contributing the shift in our industry from wastewater treatment to resource recovery. Leon was the vice chair and contributing author for the recent WEF publication Moving Towards Resource Recovery Facilities, he has served on the Issue Area Team for the WERF Resource Recovery Challenge research program, and he has been involved with the evaluation, design, and/or operation of multiple energy efficiency, biogas utilization, and struvite harvesting projects.

Kellen Lauer is an Environmental Specialist with Environmental Business Specialists (EBS), focusing in molecular microbiology. She came to EBS in August 2015 to develop a molecular biology lab with capabilities for quantitative PCR analysis of wastewater systems. Read more...

Environmental Business Specialists (EBS) is an independent wastewater consulting and training company providing a unique blend of technical expertise and customer focused services to an ever-growing list of industrial clients. Kellen graduated Phi Beta Kappa from the University of Virginia with a Bachelor of Science in Environmental Sciences. She received her Master of Science in Marine Science from the University of North Carolina at Chapel Hill where her research received a 2015 Impact Award from the UNC Graduate Education Advancement Board for efforts to increase awareness and improve notification to beach-goers during periods of poor water quality.

Jeremy Cramer has 18 years of wastewater and water treatment experience. He is a licensed water and wastewater operator in the state of Wisconsin. Throughout his career, he has been involved in the management, operation, and maintenance of both wastewater and water treatment systems and facilities. Read more...

Under his guidance, two different wastewater facilities have been recognized for operation and performance and have won Utility of the Future Today Awards from WEF. He has also overseen the operation and maintenance of sanitary liftstations, stormwater liftstations, and drinking water wells. Mr. Cramer has had a tremendous amount of experience in the area of wastewater treatment with focus areas in anaerobic digestion, biological nutrient removal, and energy efficient operations. Mr. Cramer holds a B.S. degree in biology and a M.S. degree in business management and is a Senior Process Specialist for Donohue & Associates, Inc.

Bryan Johnson, P.E., is a seasoned civil and environmental engineer with 30 years of experience in renewable bioenergy with a particular focus in biogas energy. Through the combination of his formal education and work experiences, Mr. Johnson has successfully developed well in excess of $100M in bioenergy opportunities. Read more...

His work has included identifying beneficial local synergies, considering environmental factors and siting constraints, facilitating the evolution of bioenergy project concepts, and implementing technology, all the way through to operating projects. He has detailed knowledge in design, construction and operation of bioenergy projects involving electric generation, co-generation heat recovery, alternate fuel replacements for industry, and gas processing applications to convert low quality raw biogas into a natural gas quality grade fuel as a replacement for a variety of fossil energy sources. A number of these biogas energy projects have received national recognition. Some of Mr. Johnson’s most recent work has involved a number of digester studies and working for a client to develop a $20M first-of-a-kind (in North America) anaerobic community digester system. This system collects high-strength liquid organic wastes from area food processors to produce 2 MW’s of cogeneration power while providing thermal energy to the client’s facilities. Mr. Johnson’s newly formed company, Energy Tech Innovations, LLC (ETI) is presently in the process of commercializing a new low-cost patent pending biogas upgrading system that produces Renewable Natural Gas (RNG) using water as a natural solvent to purify the gas. Mr. Johnson holds a BS in Civil and Environmental Engineering, and BS in Geology from the University of Wisconsin, Madison.

David Ellis P.E., started working with municipal sewage anaerobic digestion systems 25 years ago. Building on that experience, he has worked on large scale digesters for multi-national food-industry clients for 20 years, since before many folks had heard of green-house gases. In those days, biogas was simply a matter of good business. Read more...

He has been involved in over 300 wastewater and digester projects on 4 continents. Having previously worked for large, multi-national consulting companies, Dave’s career has come full circle as his first boss and mentor was working with early on-farm AD systems in the 80s. He is excited to be working directly with owners again and helping find solutions for unique digester issues. Mr. Ellis holds a B.Sc. in Systems Design Engineering and an M.Sc. in Chemical Engineering from the University of Waterloo. He is the Founder, Managing Director and Principal Consultant of Azura Associates, a wastewater and cleantech consultancy based in Waterloo, Ontario Canada.

Dr. David Garman will be serving as a technical advisor for this study. David is presently Associate Vice Chancellor Water Technology Research and Development, and Founding Dean of the School of Freshwater Sciences, University of Wisconsin Milwaukee. He is leading the establishment of new water research programs for industry and the environment. Read more...

His career has covered the full range of environmental management from water resources and pollution control through to new environmental technologies, covering all aspects of measurement, management policy and strategic analysis. His research and interests cover all aspects of new technology, and water resource management from research and planning to large-scale operations. Dr. Garman has served as both an executive and non-executive director for private and listed companies. He has been on boards and as an advisor for small private companies and water utilities. His experience as Managing Director of the Environmental Biotechnology Cooperative Research Center cemented his commitment to the use of applied molecular methods for environmental protection and applications in industry and the community.

Tracking Biogas Anaerobic Digester Performance using Next Generation DNA Sequencing

Autumn Fisher, City of Fond du Lac

[We use Microbe Detectives’ DNA analysis for] looking at our digester operations and looking at our methanogen populations and starting to get a better idea [of performance], because we do have a co-digestion program, we accept high-strength waste. How are those different substrates affecting our populations of methanogens within our digesters? Is it good? it is bad? What kind of changes have been made to our digestion that could affect our methane production? We have a biogas generator on site as well, so we’re utilizing that biogas. The biogas very important to us. If we can do anything to promote better biogas production that’s going to be helpful to us for energy [production]. So is [DNA Analysis] giving you more insight that you didn’t have prior? Absolutely, there’s a lot that we’ve been able to look at and quantify that we wouldn’t have been able to otherwise.