Azo dye as part of co-substrate in a biofilm electrode reactor–microbial fuel cell coupled system and an analysis of the relevant microorganisms

• Published in: Chemosphere (Oxford) 2019-02, Vol.216, p.742-748
• Main Authors: Cao, Xian, Zhang, Shuai, Wang, Hui, Li, Xianning
• Format: Article
• Language: English
• Subjects: Azo Compounds - chemistry; Azo dye; Bioelectric Energy Sources - trends; Bioelectrochemical coupled system; Biofilm electrode reactor; Biofilms; Degradation; Electrodes; Energy recycling; Microbial fuel cell
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2018.10.203

In general, refractory organics were hardly used as co-substrate in bioelectrochemical system. This study established a coupled bioelectrochemical system composed of a biofilm electrode reactor and a microbial fuel cell for using the azo dye X-3B as part of co-substrate. The two units degraded the azo dye X-3B stepwise while using it as part of co-substrate. Our results indicated that the removal efficiency of X-3B increased 28.5% using the coupled system compared with a control system. Moreover, the addition of the co-substrate glucose, which was necessary for MFC electricity generation, was reduced on the premise of stable removal efficiency in the coupled system to prevent resource waste due to using X-3B as part of co-substrate. The intermediate products of X-3B degradation were further explored using gas chromatography–mass spectrometry and a X-3B degradation pathway was proposed at the same time. Microbial communities were analyzed, illustrating that the mechanism of X-3B degradation was dependent on bioelectrochemistry rather than on microbial degradation. •The decreased co-substrate addition for a given removal efficiency was realized.•A coupled system degraded X-3B stepwise while using it as part of co-substrate.•The electricity generated by the MFC unit was used effectively by the BER unit.•No species related to specifically genera were involved in X-3B degradation.