Evaluation of an integrated continuous stirred microbial electrochemical reactor: Wastewater treatment, energy recovery and microbial community

• A novel integrated system CSMER was developed.
• COD removal of CSMER was 1.6 times higher than CSTR at OLR of 12 kg COD m−3 d−1.
• Energy recovery efficiency was improved by 2.5 times in CSMER.
• CSMER exhibited a greater level of phylogenetic diversity compared with CSTR.

A continuous stirred microbial electrochemical reactor (CSMER) was developed by integrating anaerobic digestion (AD) and microbial electrochemical system (MES). The system was capable of treating high strength artificial wastewater and simultaneously recovering electric and methane energy. Maximum power density of 583 ± 9, 562 ± 7, 533 ± 10 and 572 ± 6 mW m−2 were obtained by each cell in a four-independent circuit mode operation at an OLR of 12 kg COD m−3 d−1. COD removal and energy recovery efficiency were 87.1% and 32.1%, which were 1.6 and 2.5 times higher than that of a continuous stirred tank reactor (CSTR). Larger amount of Deltaproteobacteria (5.3%) and hydrogenotrophic methanogens (47%) can account for the better performance of CSMER, since syntrophic associations among them provided more degradation pathways compared to the CSTR. Results demonstrate the CSMER holds great promise for efficient wastewater treatment and energy recovery.