title: Minimizing nitrous oxide in biological nutrient removal from municipal wastewater by controlling copper ion concentrations.
abstract: In this study, nitrous oxide (N(2)O) production during biological nutrient removal (BNR) from municipal wastewater was reported to be remarkably reduced by controlling copper ion (Cu(2+)) concentration. Firstly, it was observed that the addition of Cu(2+) (10-100 μg/L) reduced N(2)O generation by 54.5-73.2 % and improved total nitrogen removal when synthetic wastewater was treated in an anaerobic-aerobic (with low dissolved oxygen) BNR process. Then, the roles of Cu(2+) were investigated. The activities of nitrite and nitrous oxide reductases were increased by Cu(2+) addition, which accelerated the bio-reductions of both nitrite to nitric oxide (NO                   (2)                             (-)                  → NO) and nitrous oxide to nitrogen gas (N(2)O → N(2)). The quantitative real-time polymerase chain reaction assay indicated that Cu(2+) addition increased the number of N(2)O reducing denitrifiers. Further investigation showed that more polyhydoxyalkanoates were utilized in the Cu(2+)-added system for denitrification. Finally, the feasibility of reducing N(2)O generation by controlling Cu(2+) was examined in two other BNR processes treating real municipal wastewater. As the Cu(2+) in municipal wastewater is usually below 10 μg/L, according to this study, the supplement of influent Cu(2+) to a concentration of 10-100 μg/L is beneficial to reduce N(2)O emission and improve nitrogen removal when sludge concentration in the BNR system is around 3,200 mg/L.
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: Xiaoyu
authors.initials: X
authors.lastname: Zhu
authors.forename: Yinguang
authors.initials: Y
authors.lastname: Chen
authors.forename: Hong
authors.initials: H
authors.lastname: Chen
authors.forename: Xiang
authors.initials: X
authors.lastname: Li
authors.forename: Yongzhen
authors.initials: Y
authors.lastname: Peng
authors.forename: Shuying
authors.initials: S
authors.lastname: Wang
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D058448:Biota; D003300:Copper / Q000378:metabolism*; D007287:Inorganic Chemicals / Q000378:metabolism*; D009572:Nitrite Reductases / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism; D009609:Nitrous Oxide / Q000037:antagonists & inhibitors* / Q000378:metabolism; D009930:Organic Chemicals / Q000378:metabolism*; D010088:Oxidoreductases / Q000378:metabolism; D054813:Polyhydroxyalkanoates / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology*
chemical_list: D003300:Copper; D007287:Inorganic Chemicals; D009572:Nitrite Reductases; D009584:Nitrogen; D009609:Nitrous Oxide; D009930:Organic Chemicals; D010088:Oxidoreductases; D054813:Polyhydroxyalkanoates; D062065:Wastewater; C022763:nitrous oxide reductase