title: Biological nutrient removal with low nitrous oxide generation by cancelling the anaerobic phase and extending the idle phase in a sequencing batch reactor.
abstract: Although wastewater biological nutrient removal can be achieved by alternating the anaerobic-oxic-anoxic phases, significant amount of nitrous oxide (N2O) is generated in oxic phases, where ammonia-oxidizing bacteria (AOB) rather than heterotrophic denitrifiers are the main contributors. Here a new efficient strategy to remarkably reduce N2O generation was reported. It was found that by cancelling the anaerobic phase and extending the idle phase the N2O generation was reduced by 42% using synthetic wastewater, whereas the total nitrogen and phosphorus removals were unaffected. The mechanistic investigations revealed that the cancelling of anaerobic phase benefited heterotrophic denitrifiers instead of AOB to be responsible for nitrogen removal in the oxic phases, increased the ratio of total nitrogen removal driven by external carbon source, and decreased nitrite accumulation. Quantitative real-time polymerase chain reaction and fluorescence in situ hybridization analyses further showed that the new strategy increased the number of N2O reducing bacteria but decreased the abundance of glycogen accumulating organisms, with N2O as their primary denitrification product. It was also determined that the ratio of nitric oxide reductase activity to N2O reductase activity was significantly decreased after anaerobic phase was cancelled. All these observations were in accord with the reduction of N2O production. The feasibility of this strategy to minimize the generation of N2O was finally confirmed for a real municipal wastewater. The results reported in this paper provide a new viewpoint to reduce N2O generation from wastewater biological nutrient removal.
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Yinguang
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China. Electronic address: w.dongbo@yahoo.com.
authors.forename: Dongbo
authors.initials: D
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Xiong
authors.initials: X
authors.lastname: Zheng
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Leiyu
authors.initials: L
authors.lastname: Feng
authors.affiliation: State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science and Engineering, Tongji University, 1239 Siping Road, Shanghai 200092, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
mesh_terms: D000641:Ammonia / Q000737:chemistry / Q000378:metabolism; D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D018407:Bacterial Physiological Phenomena; D019149:Bioreactors / Q000382:microbiology*; D058440:Denitrification; D009584:Nitrogen / Q000737:chemistry / Q000378:metabolism*; D009609:Nitrous Oxide / Q000737:chemistry / Q000378:metabolism*; D010758:Phosphorus / Q000737:chemistry / Q000378:metabolism; D014865:Waste Disposal, Fluid / Q000295:instrumentation / Q000379:methods*; D062065:Wastewater / Q000737:chemistry*
chemical_list: D000641:Ammonia; D009584:Nitrogen; D009609:Nitrous Oxide; D010758:Phosphorus; D062065:Wastewater
keywords: Aerobic/extended-idle phosphorus removal regime; Ammonia-oxidizing bacteria; Biological nutrient removal; Nitrous oxide reduction