The impact of methane gas on climate change is growing as warmer temperatures accelerate microbial methane emissions in nature. Water Institute member Hyung-Sool Lee, an associate professor in Department of Civil and Environmental Engineering, is discovering innovative ways to deal with this problem. His recent publication, “Kinetic study on anaerobic oxidation of methane coupled to denitrification,” offers new ideas about how to mitigate atmospheric methane efflux through anaerobic oxidation of methane (AOM).
The Water Institute had the opportunity to learn more about Hyung-Sool’s research, the Waterloo Environmental Biotechnology Lab he runs, and why he believes interdisciplinary research is important when it comes to tackling complex water problems.
Associate professor Hyung-Sool Lee, Department of Civil and Environmental Engineering
Can you explain anaerobic oxidation of methane (AOM) and the role it plays in mitigating atmospheric methane efflux? What impact does this have on the environment?
Understanding and controlling methane emissions is extremely important as methane is one of the significant compounds causing global climate change. Scientists have estimated AOM would account for 10-60% of the global methane emissions, which means that without AOM we will have huge methane emissions, worsening the impacts of climate change.
AOM coupled to denitrification (AOM-D) simultaneously impacts two important global cycles of carbon and nitrogen. Can you elaborate on the significant implications of this?
AOM can occur in syntrophy with sulfate reduction or nitrate reduction. Some recent works reported AOM coupled to metal reduction. Due to the wide distribution and presence of nitrate in natural environments over other compounds – especially subsurface environments that include groundwater – understanding AOM-D is vital.
Your research paper states that, “AOM-D application to existing wastewater treatment plants with anaerobic digesters can save substantial chemical costs associated with exogenous electron donor (e.g., methanol) necessary for denitrification by using methane gas generated on site.” Is AOM-D a widely-used application in wastewater treatment plants?
AOM-D is in an embryonic stage, it’s a truly emerging topic. However, engineering AOM-D can improve energy efficiency in nitrogen removal in water and wastewater. To engineer AOM-D, including any other biotechnologies, comprehension of kinetic features is essential. Our article was the first to characterize AOM-D kinetics.
You lead the Waterloo Environmental Biotechnology Lab, what is your research group currently working on?
Our group has worked on two fundamental themes: (1) Anaerobic oxidation of methane and (2) extracellular electron transfer. In applied science, our group has studied (1) energy-efficient organic wastewater treatment, (2) recovery of value-added products from food waste, and (3) energy-independent biosensors for biochemical oxygen demand.
MBfRs featuring AOM-D in Hyung-Sool Lee's Waterloo Biotechnology Lab.
Why is interdisciplinary collaboration becoming an important part of solving the world’s complex water problems?
As we have studied challenges and problems related to water, we realized that they are more complicated than we expected. For instance, engineering AOM-D needs deep understanding of AOM-D reactions, related microorganisms, growth conditions, kinetic parameters, etc. In addition, we need to comprehend which microorganisms can conduct AOM-D in mixed culture or pure culture. Who is a main player in AOM-D? What biochemical reaction is a kinetic bottleneck? After understanding important fundamentals, we need to invest our efforts toward applications. In this stage, an engineering approach will play a vital role. We completed engineering AOM-D using gas-permeable membranes for methane supply in a bioreactor, and expect to move to the pilot stage. Our lab ideally merges fundamentals with applications to develop innovative biotechnologies. Interdisciplinary research (mainly with biology and material science experts) improves research quality and accelerates research progress.
About Hyung-Sool Lee
- Production of bio-energy (electricity, H2, and CH4) and bio-chemicals from biomass
- Nutrients recovery from organic waste and wastewater
- Thermodynamic/kinetic analyses on microbial metabolisms in engineered and natural systems
He leads the Waterloo Environmental Biotechnology Lab and has taught:
- ENVE 276 - Environmental Biology and Biotechnology
- ENVE 375 - Water Quality Engineering
- CIVE 671 - Aquatic Chemistry