title: Impacts of CuO nanoparticles on nitrogen removal in sequencing batch biofilm reactors after short-term and long-term exposure and the functions of natural organic matter.
abstract: The impacts of CuO nanoparticle (NP) exposure on total nitrogen (TN) removal in a sequencing batch biofilm reactor (SBBR) as well as the effects of natural organic matter (NOM) in wastewater were studied. Short-term exposure (8 h) to 1 and 50 mg/L CuO NPs induced negligible influence on the nitrogen removal efficiency, and biofilms could recover from the slight damage caused by the prolonged exposure (45 days) to 1 mg/L CuO NPs. On the other hand, long-term exposure to 50 mg/L CuO NPs notably decreased the nitrogen removal efficiencies to 47.74 and 59.04 % in the absence and presence of bovine serum albumin (BSA), much lower than those in the control (75.43 %), mainly as the suppressed denitrification process. Analysis of key enzyme activities showed that the activities of nitrite reductase and nitrate reductase were obviously reduced with 50 mg/L CuO NP exposure. Further studies revealed that the inhibited nitrite/nitrate reductase was related to the variations of microenvironment pH and decrease of nirS and nirK by microelectrode and fluorescent quantitative polymerase chain reaction (PCR) analysis. In addition, the presence of BSA mitigated the toxicity of CuO NPs due to the enhanced particle size and Cu2+release, electrostatic repulsion, and surface coating of CuO NPs, which indicated that lower inhibition effects of CuO NPs in NOM-rich wastewater is of importance when evaluating the environmental risk of NPs to wastewater treatment plants.
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Jun
authors.initials: J
authors.lastname: Hou
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Guoxiang
authors.initials: G
authors.lastname: You
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China. pfwang2005@hhu.edu.cn.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China. pfwang2005@hhu.edu.cn.
authors.forename: Peifang
authors.initials: P
authors.lastname: Wang
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Lingzhan
authors.initials: L
authors.lastname: Miao
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Yanhui
authors.initials: Y
authors.lastname: Ao
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Bowen
authors.initials: B
authors.lastname: Lv
authors.affiliation: Key Laboratory of Integrated Regulation and Resources Development on Shallow Lakes, Ministry of Education, Hohai University, Nanjing, 210098, People's Republic of China.|College of Environment, Hohai University, 1 Xikang Road, Nanjing, 210098, People's Republic of China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Yang
mesh_terms: D001419:Bacteria / Q000378:metabolism; D018407:Bacterial Physiological Phenomena; D018441:Biofilms; D019149:Bioreactors; D003300:Copper / Q000378:metabolism*; D006812:Humic Substances / Q000032:analysis; D053768:Metal Nanoparticles; D009584:Nitrogen / Q000378:metabolism*; D013997:Time Factors; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000032:analysis; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D003300:Copper; D006812:Humic Substances; D009584:Nitrogen; D062065:Wastewater; D014874:Water Pollutants, Chemical; C030973:cupric oxide
keywords: CuO nanoparticles; Microenvironment; Nitrogen removal; Quantitative polymerase chain reaction; Sequencing batch biofilm reactor (SBBR)