LAUSR

Abstract A bioelectrochemical trickling filter bed reactor (BE-TFBR) was studied as a post-treatment process to upgrade biogas and treat digestate. The trickling filter bed reactor (TFBR) was efficient in upgrading the biogas from 53% to 83%, but it was not effective in removing the chemical oxygen demand (COD) of the digestate (the COD removal efficiency was less than 11%). The BE-TFBR hydraulically induced a high rate of CH4 conversion from the CO2 in the biogas that had injected H2, and it bioelectrochemically improved the removal of residual COD from the digestate. The maximum CH4 content, CH4 production, and COD removal efficiencies in a continuously operated BE-TFBR were 90.5%, 3.52 L/d, and 31.2%, respectively. The BE-TFBR contributed to the further removal of COD (by 0.48 g/d) and to the additional production of CH4 (by 0.31 L). These results are better than those obtained by using a TFBR alone and show that the BE-TFBR could be applied as an effective post-treatment process to remove residual COD in digestate and to qualitatively and quantitatively improve biogas production from wastes.