Nitrous oxide (N2O) is a potent greenhouse gas that originates mainly from various biological reactions, including nitrification and denitrification. The sole sink of N2O, biological N2O reduction has long been discounted as one of the reactions constituting the denitrification pathway. However, recently, the possibility of utilizing microbial N2O reduction as an independent energy-conserving reaction for reducing N2O emissions from the its hotspots has gained attention from the scientific world and the industry alike. Prof. Yoon’s recent research revealed that certain groups of nosZ-possessing organisms have significantly higher affinity towards N2O, and have identified a naturally-abundant obligate aerobe, Gemmatimonas spp., as being capable of carrying out N2O reduction, which is a strictly anaerobic process. Prof. Yoon’s research group at KAIST has taken a step further from merely understanding these N2O-reducers to putting them into engineering practice, by designing biofilter-type reactors utilizing naturally enriched high-affinity N2O reducers for removal of low-concentration N2O from the off-gas streams from activated sludge tanks of wastewater treatment plants. Successfully verified of its feasibility in laboratory experiments, the biofiltration system is currently under examination at a pilot plant constructed at an actual wastewater treatment plant in Gapyeong, Korea.
Sukhwan Yoon is an Associate Professor at the Korea Advanced Institute of Science and Technology.