N 2 O profiles in the enhanced CANON process via long-term N 2 H 4 addition: minimized N 2 O production and the influenc
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ENVIRONMENTAL TOXICOLOGY AND BIOGEOCHEMISTRY OF ECOSYSTEMS
N2O profiles in the enhanced CANON process via long-term N2H4 addition: minimized N2O production and the influence of exogenous N2H4 on N2O sources Pengying Xiao 1 & Shuo Ai 1 & Jing Zhou 1 & Xiaojing Luo 1 & Baowen Kang 1 & Li Feng 2 & Tiantao Zhao 1 Received: 14 July 2019 / Accepted: 10 September 2019 # Springer-Verlag GmbH Germany, part of Springer Nature 2019
Abstract Production of the greenhouse gas nitrous oxide (N2O) from the completely autotrophic nitrogen removal over nitrite (CANON) process is of growing concern. In this study, the effect of added hydrazine (N2H4) on N2O production during the CANON process was investigated. Long-term trace N2H4 addition minimized N2O production (0.018% ± 0.013% per unit total nitrogen removed) and maintaining high nitrogen removal capacity of CANON process (nitrogen removal rate and TN removal efficiency was 450 ± 60 mg N/L/day and 71 ± 8%, respectively). Ammonium oxidizing bacteria (AOB) was the main N2O producer. AOB activity inhibition by N2H4 decreased N2O production during aeration, and the N2H4 concentration was negatively correlated with N2O production rate in NH4+ oxidation via AOB, whereas N2O production was facilitated under anaerobic conditions because hydroxylamine (NH2OH) production was accelerated due to anammox bacteria (AnAOB) activity strengthen via N2H4. Added N2H4 completely degraded in the initial aeration phases of the CANON SBR, during which some N2H4 intensified anammox for total nitrogen removal to eliminate N2O production from nitrifier denitrification (ND) by anammox-associated, while the remaining N2H4 competed with NH2OH for hydroxylamine oxidoreductase (HAO) in AOB to inhibit intermediates formation that result in N2O production via NH2OH oxidation (HO) pathway, consequently decreasing total N2O production. Keywords Completely autotrophic nitrogen removal over nitrite . N2H4 . Nitrous oxide . NH2OH oxidation . Nitrifier denitrification . Anammox
Introduction The completely autotrophic nitrogen removal over nitrite (CANON) (Sliekers et al. 2002) process combines nitritation and anaerobic ammonium (NH4+) oxidization (anammox)
Pengying Xiao and Shuo Ai contributed to the work equally and should be regarded as co-first authors. Responsible editor: Bingcai Pan * Pengying Xiao [email protected] * Tiantao Zhao [email protected] 1
College of Chemistry and Chemical Engineering, Chongqing University of Technology, No. 69 Hongguang Avenue, Chongqing 400054, Banan District, People’s Republic of China
2
Chongqing Academy of Environmental Science, Chongqing 400054, People’s Republic of China
into a single process, in which aerobic ammonium oxidizing bacteria (AOB) partially oxidize NH4+ to nitrite (NO2−), while anammox bacteria (AnAOB) convert the resulting NO2− and any remaining NH4+ into nitrogen gas (N2). The CANON process is a cost-effective and energy-efficient alternative to the conventional nitrogen removal process because of its reduced oxygen and carbon source demands (Sli
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