A novel inhibition mechanism of aniline on nitrification: Aniline degradation competes dissolved oxygen with nitrification

Yanyan Fan; Xiaolei Chen; Zhangyi Yao; Haisong Li; Dandan Wang; Minhui Tian; Zicong Xu; Junfeng Wan

doi:10.1016/j.scitotenv.2021.145205

A novel inhibition mechanism of aniline on nitrification: Aniline degradation competes dissolved oxygen with nitrification

Sci Total Environ. 2021 May 20:770:145205. doi: 10.1016/j.scitotenv.2021.145205. Epub 2021 Jan 22.

Authors

Yanyan Fan¹, Xiaolei Chen², Zhangyi Yao², Haisong Li³, Dandan Wang¹, Minhui Tian¹, Zicong Xu¹, Junfeng Wan⁴

Affiliations

¹ College of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China; ZhiHe Environmental Science and Technology Co., Ltd., Zhengzhou 450001, China.
² ZhiHe Environmental Science and Technology Co., Ltd., Zhengzhou 450001, China.
³ College of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China. Electronic address: lhs@zzu.edu.cn.
⁴ College of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China.

PMID: 33515876
DOI: 10.1016/j.scitotenv.2021.145205

Abstract

Aniline is a toxic aromatic amine and an inhibitor of nitrification. This study explored the inhibition effect and underlying mechanism. After sludge acclimation, 540 mg/L aniline was removed in 24 h and almost all ammonia released from aniline was oxidized to nitrate. However, nitrification never started until no aniline left. The cellular adenosine triphosphate (cATP) concentration of acclimated sludge reduced only by 2% after aniline exposure. Neither transmembrane transport of ammonia nor ammonia monooxygenase (AMO) activity was affected by aniline. Growing initial aniline concentration did not deteriorate the specific nitrification rate (NR). These all revealed that the toxicity of aniline only play a minor role in inhibition. Competition for dissolved oxygen (DO) was proposed to be another possible inhibition mechanism. The oxygen affinity constant (Ks) of aniline degraders and ammonia-oxidizing bacteria (AOB) was calculated to be 0.894 mg/L and 1.274 mg/L respectively, suggesting the former possessed much stronger oxygen affinity (P < 0.01). With aniline and ammonium as initial substrates, increasing aeration intensity advanced nitrification and increased the NR. Max NR of 0.63 mgN/(gMLSS·h) was achieved at the highest aeration intensity of 1000 mL/min. This study brings one step closer to better removal of aniline and derived nitrogen pollutants.

Keywords: Aeration intensity; DO competition; NR; Oxygen affinity; cATP.