Abstract:[Objective] Microbial electrolysis cells (MEC) have been newly developed by employing anodic respiring bacteria to degrade waste organics to electrons. And hydrogen is recovered directly on the cathode surface under a very small external voltage to apply between anode and cathode. Although MECs showed great potential on high efficiency both on organic removal and energy recovery, there is a limited factor to enrich high-efficiency functional communities for scaled up reactors. [Methods] microbial community structure and characteristic of electron transport were analyzed through single-strand conformation poly-morphism (SSCP). [Results] The results showed that MECs were successfully started up within 2 days with coulombic efficiency of 20%. The hydrogen was produced steadily after 7 days with a conversion yield of 30% and energy recovery rate of 90%. SSCP analysis indicated that Pseudomonas sp., Flavobacterium sp., Ochrobactrum sp. as the main bacterial community related to electron transfer when inoculating the anode biofilm from microbial fuel cell. While a higher diversity presented when inoculating the anode biofilm of former MECs, and the dominant bacteria were including Desulfovibrio, Pseudomonas, and Shewanella, which were reported high efficiency on electron transport. In addition, it was uncovered the important role of the co-existing bacteria related to anaerobic digestion or assistance to electron transfer, showing an important function to support a stable anodic biofilm structure. [Conclusion] The results illustrated that high reactor performances with higher microbial diversity can be obtained using MEC biofilms as inoculum for large MEC reactor setup.
