Electrolysis-sulfate-reducing up-flow sludge bed-biological contact oxidation reactor for Norfloxacin removal from wastewater with high sulfate content

• Published in: Environmental research Vol. 196; p. 110455
• Main Authors: Gao, Jinlong, Chen, Yifan, Li, Jiwei, Yu, Yalin, Wang, Jun, Pang, Tiantian, Qi, Yuting, Shang, Jingge, Liao, Qianjiahua
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.05.2021
• Subjects: Degradation pathway; Electrolysis-anaerobic-aerobic system; Microbial community analysis; Norfloxacin; Sulfate-containing wastewater; Microbial community analysis; Norfloxacin; Degradation pathway; Sulfate-containing wastewater; Electrolysis-anaerobic-aerobic system
• ISSN: 0013-9351; 1096-0953
• DOI: 10.1016/j.envres.2020.110455

This study investigated the treatment of 100-mg/L Norfloxacin (NOR) wastewater containing high concentrations of sulfate through a combination of electrolysis, sulfate-reducing up-flow sludge bed (SRUSB), and biological contact oxidation reactor (BCOR) treatments. Results revealed that after 62 h, the reaction system had processed over 97% of the NOR. Additionally, electrolysis with sodium sulfate as the electrolyte transformed 87.8% of the NOR but only 33.5% of the total organic carbon (TOC). In the SRUSB, the TOC and SO42− contents were simultaneously reduced by 87.4% and 95.6%, respectively, providing a stable environment to the BCOR. In the BCOR, 36.3% and 85.9% of the NOR and TOC were degraded. High-performance liquid chromatography-tandem mass spectrometry analysis identified three possible degradation pathways under the attack of –OH during electrolysis, including defluorination, piperazinyl ring transformation, and quinolone ring transformation. Furthermore, the Illumina HiSeq sequencing results demonstrated that the sulfate-reducing bacteria (represented by Desulfobacter and Desulfobulbus) in the SRUSB and the sulfate-oxidizing bacteria (mainly consisting of Gammaproteobacteria and Alphaproteobacteria) in the BCOR played important roles in carbon chain oxidation and benzene ring opening and thoroughly degraded the electrolysis products. Thus, this method effectively overcomes the incomplete degradation and low removal efficiency issues associated with single electrolysis or biological methods in traditional processes. •Norfloxacin (NOR) wastewater is treated by an electrolysis-anaerobic-aerobic system.•Defluorination and piperazinyl/quinolone ring transformation degrade the NOR.•After 62 h, the system processes over 97% of the NOR.•Sulfate-reducing and -oxidizing bacteria play important roles in different reactors.