Ag-TiO2/biofilm/nitrate interface enhanced visible light-assisted biodegradation of tetracycline: The key role of nitrate as the electron accepter

Cheng Hou; Xinbai Jiang; Dan Chen; Xiaoyu Zhang; Xiaodong Liu; Yang Mu; Jinyou Shen

doi:10.1016/j.watres.2022.118212

Ag-TiO₂/biofilm/nitrate interface enhanced visible light-assisted biodegradation of tetracycline: The key role of nitrate as the electron accepter

Water Res. 2022 May 15:215:118212. doi: 10.1016/j.watres.2022.118212. Epub 2022 Feb 21.

Authors

Cheng Hou¹, Xinbai Jiang², Dan Chen¹, Xiaoyu Zhang¹, Xiaodong Liu¹, Yang Mu³, Jinyou Shen⁴

Affiliations

¹ Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China.
² Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. Electronic address: xinbai_jiang@njust.edu.cn.
³ Department of Applied Chemistry, CAS Key Laboratory of Urban Pollutant Conversion, University of Science and Technology of China, Hefei 230026, China.
⁴ Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, China. Electronic address: shenjinyou@mail.njust.edu.cn.

PMID: 35255424
DOI: 10.1016/j.watres.2022.118212

Abstract

Due to the pivotal role of Ag-TiO₂/biofilm/nitrate interface, enhanced visible light-assisted biodegradation of tetracycline (TC) in anoxic system was realized through both batch experiment and long-term operation in this study. The results of the batch experiment elucidated that 50 mg L^-1 TC could be completely removed within 10 h in Ag-TiO₂/biofilm/nitrate system. The continuous flow experiment was operated for 75 d to evaluate the performance and stability of Ag-TiO₂/biofilm/nitrate system. TC removal efficiency in Ag-TiO₂/biofilm/nitrate system was as high as 92.4 ± 1.6% at influent TC concentration of 50 mg L^-1 TC and hydraulic retention time (HRT) of 10 h, which would be attributed to the promoted separation of photoholes and photoelectrons at the presence of nitrate as electron acceptor. Facilitated electron transfer between semiconductor and biofilm was beneficial for enhancing TC biodegradation, thus lowering toxicity of intermediate products and promoting microbial activity. Moreover, the species related to TC biodegradation (Rhodopseudomonas, Phreatobacter and Stenotrophomonas), denitrification (Thauera) and electron transfer (Delftia) were enriched at Ag-TiO₂/biofilm/nitrate interface. Besides, a possible mechanism involved in enhanced TC degradation and nitrogen removal at Ag-TiO₂/biofilm/nitrate interface was proposed. This study provided a novel and promising strategy to enhance recalcitrant TC removal from industrial wastewater.

Keywords: Ag-TiO(2)/biofilm/nitrate interface; Denitrification; Electron transfer; Microbial community; Tetracycline.

MeSH terms

Biofilms
Bioreactors
Denitrification
Electrons*
Light
Nitrates*
Tetracycline
Titanium

Substances

Nitrates
titanium dioxide
Titanium
Tetracycline