Mechanisms of metabolic performance enhancement during electrically assisted anaerobic treatment of chloramphenicol wastewater

• Published in: Water research (Oxford) 2019-06, Vol.156, p.199-207
• Main Authors: Guo, Ning, Ma, Xiaofang, Ren, Shaojie, Wang, Shuguang, Wang, Yunkun
• Format: Article
• Language: English
• Subjects: Anaerobic treatment; Antibiotic-resistant bacteria; Chloramphenicol wastewater; Functional bacteria; Methane production
• ISSN: 0043-1354; 1879-2448
• DOI: 10.1016/j.watres.2019.03.032

The anaerobic process is a favorable alternative for the treatment of antibiotic pharmaceutical wastewater. The electrically assisted anaerobic process can be used to accelerate contaminant removal, especially for persistent organic pollutants such as antibiotics. In this study, an electrically assisted anaerobic system for chloramphenicol (CAP) wastewater treatment was developed. The system performance and the underlying metabolic mechanisms were evaluated under different applied voltages. With the increase of applied voltage from 0 to 2 V, the CAP removal efficiencies increased from 53.3% to 89.7%, while the methane production increased more than three times. The microbial community structure and correlation analysis showed that electrical stimulation selected the dominant functional bacteria and increased antibiotic resistance in dominant functional bacteria, both of which enhanced CAP removal and methane production. The improved CAP removal was a result of the presence of dechlorination-related bacteria (Acidovorax, Sedimentibacter, Thauera, and Flavobacterium) and potential electroactive bacteria (Shewanella and Comamonas), both of which carried ARGs and therefore could survive the biotoxicity of CAP. The enhanced methane production could be partly attributed to the surviving fermentative-related bacteria (Paludibacter, Proteiniclasticum, and Macellibacteroides) in the anaerobic bioreactor. The increased abundances of methanogenic genes (mcrA and ACAS genes) under high voltage further confirmed the enhanced methane production of this electrically assisted anaerobic system. The fundamental understanding of the mechanisms underlying metabolic performance enhancement is critical for the further development of anaerobic wastewater treatment. [Display omitted] •An electrically assisted anaerobic system can be used for CAP wastewater treatment.•The surviving functional bacteria carrying ARGs improved the system performance.•Enrichment of fermentative-related species carrying ARGs increased CH4 production.•The abundances FTHFS, mcrA and ACAS genes revealed the mechanism of CH4 production.•Pollutant reduction-related species and electroactive species carrying ARGs enhanced CAP removal.