Electrolysis enhanced anaerobic baffled reactor as retrofitting approach for molasses based distillery wastewater treatment

This study evaluates the performance of electrolysis enhanced anaerobic baffled reactor (EABR), as an approach for retrofitting anaerobic unit treating molasses based distillery wastewater. For this purpose, a pilot with six chambers having total volume of 140 L was operated for more than 6 months inoculated with high-strength influent. Regarding the experimental results, the conventional anaerobic baffled reactor (ABR) could efficiently remove soluble chemical oxidation demand (COD) and volatile fatty acids (VFAs) to 90% and 92%, respectively. Here, the biogas productivity reached 0.96 LL(-1)d(-1) in which methane constituted 70% and yielded 0.55 m(3)/kg COD. However, this system showed instability and vulnerability in lower hydraulic retention time (HRT) below 3 d as a matter of pH reduction. The overall COD removal, biogas productivity and its methane content were limited to 40%, 0.25 LL(-1)d(-1) and 45%, respectively. Therefore, the electrolysis cell was introduced in first chamber for retrofitting ABR. The EABR showed significant outcome in low HRT. This innovation could disintegrate the substrate and prevent pH from decline. Both could restore COD removal efficiency and biogas production to more than 70% and 0.6 LL(-1)d(-1), respectively, in HRT of 1.5 d. Nevertheless, methane yield could not exceed 0.17 m(3)/kg COD. Consequently, EABR was verified as an efficient approach and recovery strategy for controlling the adverse effects of low HRT, pH reduction or high organic loads in operation.