Polarized electrode enhances biological direct interspecies electron transfer for methane production in upflow anaerobic bioelectrochemical reactor

​The influence of polarized electrodes on the methane production, which depends on the sludge concentration,

was investigated in upflow anaerobic bioelectrochemical (UABE) reactor. When the polarized

electrode was placed in the bottom zone with a high sludge concentration, the methane production was

5.34 L/L.d, which was 53% higher than upflow anaerobic sludge blanket (UASB) reactor. However, the

methane production was reduced to 4.34 L/L.d by placing the electrode in the upper zone of the UABE

reactor with lower sludge concentration. In the UABE reactor, the methane production was mainly

improved by the enhanced biological direct interspecies electron transfer (bDIET) pathway, and the

methane production via the electrode was a minor fraction of less than 4% of total methane production.

The polarized electrodes that placed in the bottom zone with a high sludge concentration enhance the

bDIET for methane production in the UABE reactor and greatly improve the methane production.