Nitrification performance and bacterial community dynamics in a membrane bioreactor with elevated ammonia concentration: The combined inhibition effect of salinity, free ammonia and free nitrous acid on nitrification at high ammonia loading rates

• DOI: 10.1016/j.scitotenv.2022.154972
• Publication Date: 2022-03-31T21:05:33Z
• Authors: Huaihao Xu; Yuepeng Deng; Jie Zou; Kaoming Zhang; Xiuying Li; Yunhua Yang; Shuangqiu Huang; Zhao-Qing Liu; Zhu Wang; Chun Hu
• Keywords: Salinity; Bacteria; Sewage; Betaproteobacteria; Nitrous Acid; 04 agricultural and veterinary sciences; Nitrification; 6. Clean water; Bioreactors; Ammonia; 0401 agriculture, forestry, and fisheries; Nitrosomonas; Oxidation-Reduction; Phylogeny

The responses of the operational performance and bacterial community structure of a nitrification membrane bioreactor (MBR) to elevated ammonia loading rate (ALR) were investigated. Effective nitrification performance was achieved at high ALR up to 3.43 kg NH4+-N/m3·d, corresponding to influent NH4+-N concentration of 2000 mg/L. Further increasing influent NH4+-N concentration to 3000 mg/L, the MBR system finally became completely inefficient due to the combined inhibition effect of salinity, free ammonia and free nitrous acid on nitrification. Ammonia-oxidizing bacteria (AOB) Nitrosomonas were enriched with the increase of ALR. The relative abundance of Nitrosomonas in the sludge with ALR of 2.57 kg NH4+-N/m3·d was up to 14.82%, which were 9-fold and 53-fold higher than that in seed sludge and the sludge with ALR of 0.10 kg NH4+-N/m3·d, respectively. The phylogenetic analysis of AOB amoA genes showed that Nitrosomonas europaea/mobilis lineage are chiefly responsible for catalyzing ammonia oxidation at high ALRs.