Enhanced degradation of quinoline by coupling microbial electrolysis cell with anaerobic digestion simultaneous.

• The quinoline wastewater treatment was first investigated in the MEC-AD system. • The performance of quinoline degradation was strengthened at a voltage of 1.0 V. • CH 4 production was increased to 1.5-fold in MEC-AD compared to the AD. • Simultaneous quinoline-C and quinoline-N removal were achieved in MEC-AD. • Exoelectrogens, methanogens, anammox and degradation bacteria have coexisted. In this study, the feasibility of quinoline-wastewater treatment was investigated in a coupled microbial electrolysis cell and anaerobic digestion system (MEC-AD). Improved degradation and enhanced mineralization of quinoline were obtained, and the optimal voltage was determined to be 1.0 V. Effective removal of quinoline at relative high concentration, and a 1.5-fold increase in methane production were achieved. The results indicated that the MEC-AD could simultaneously remove carbon and nitrogen from quinoline. Gas chromatography-mass spectrometry analysis identified 2-hydroxyquinoline and 8-hydroxycoumarin as the intermediates of quinoline. The formation and degradation of metabolites were rapid, and they did not accumulate in the MEC-AD. The results of microbial community structure analysis demonstrated that the functional species were enriched and coexisted, and that the dominant bacterial genera were SM1A02 , Comamonas , Desulfovibrio , Geobacter, and Actinomarinales_norank ; the dominant archaeal genera were Methanocorpusculum and Nitrosoarchaeum. Furthermore, the applied current played a selective role in the enrichment of microorganisms. [ABSTRACT FROM AUTHOR]