Accelerating anaerobic digestion process with novel single chamber microbial electrochemical systems with baffle

[Display omitted] •MES with baffle enhanced methane production with high energy efficiency.•Increased COD removal and less VFAs accumulation were observed in MES-B.•Cathode biofilm in MES-B was enriched with electroactive Methanothrix and Firmicutes. A newly designed microbial electrochemical system (MES) with the addition of a baffle between the electrodes was integrated with the anaerobic digestion (AD) process for biogas upgradation. Novel MES configuration attained an increased methane production rate of 292.6 mL/L∙d and methane yield of 0.36 ± 0.006 LCH4/gCOD, which were higher than the values (185.3 mL/L∙d and 0.33 ± 0.009 LCH4/gCOD) from the MES operation without baffle, respectively. Moreover, the MES with baffle operation resulted in increased substrate removal (88.4 ± 0.5%) and less volatile fatty acids accumulation with a high energy efficiency of 99.6 %. Microbial community analysis revealed that acids metabolizing bacteria, Firmicutes, and Methanothrix were highly enriched in the cathode biofilm of MES with baffle. This study suggests that the baffle addition into the single chamber MES is beneficial to further improve the methanogenesis process for practical applications in the scaled-up MES-AD process.