title: Enrichment and characterization of acid-tolerant nitrifying sludge.
abstract: Nitrification is an acidifying process that requires the addition of external alkalinity because of the alkaliphilic nature of the most ammonia-oxidizing bacteria. In this study, aerobic activated sludge was used as inoculum in an internal loop air-lift reactor, which resulted in successful enrichment of acid-tolerant nitrifying (ACIN) sludge at pH 6.0 by sequential addition of tea orchard soil suspension. The results showed that ACIN sludge had a remarkable acid tolerant capability with a volumetric ammonia conversion rate of 1.13 kg N m-3day-1. ACIN sludge showed a higher maximum specific ammonia conversion rate (0.29 g N g-1VSS day-1) than neutrophilic nitrifying sludge (0.14 g N g-1VSS day-1) at pH 6.0 and had good resistance against pH fluctuations, with a maximum specific ammonia conversion rate (0.584 g N g-1VSS day-1) at pH 7.5. Microbial community analysis indicated that the higher abundance of acid tolerant Nitrosospira and ammonia-oxidizing archaea laid a solid foundation for the remarkable acid-tolerant capability of ACIN sludge.
authors.affiliation: Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
authors.forename: Lan
authors.initials: L
authors.lastname: Wang
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China. Electronic address: pzheng@zju.edu.cn.
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Department of Chemical Engineering, University of Gujrat, Pakistan.
authors.forename: Ghulam
authors.initials: G
authors.lastname: Abbas
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors.forename: Yajuan
authors.initials: Y
authors.lastname: Xing
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: Department of Environmental Engineering, Zhejiang University, Hangzhou 310058, China.
authors.forename: Ru
authors.initials: R
authors.lastname: Wang
authors.affiliation: Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
authors.forename: Liangwei
authors.initials: L
authors.lastname: Deng
authors.affiliation: Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Lei
authors.affiliation: Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Zheng
authors.affiliation: Biogas Institute of Ministry of Agriculture, Chengdu 610041, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu 610041, China.
authors.forename: Yunhong
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000143:Acids / Q000737:chemistry*; D000641:Ammonia / Q000378:metabolism*; D001105:Archaea / Q000378:metabolism*; D019149:Bioreactors; D006801:Humans; D058465:Nitrification; D012722:Sewage / Q000737:chemistry* / Q000382:microbiology
chemical_list: D000143:Acids; D012722:Sewage; D000641:Ammonia
keywords: Acid-tolerance mechanism; Acid-tolerant nitrifying bacteria; Ammonia-oxidizing archaea; Nitrosospira; Sludge characteristics