Performance evaluation of fixed bed anaerobic baffled reactor and its upgrading by integrated electrocoagulation process for municipal wastewater treatment

Anaerobic baffled reactor is efficient for wastewater treatment, while it lacks efficient nutrient removal and must be upgraded. The present study aimed to evaluate performance of fixed-bed media anaerobic baffled reactor (FABR) for municipal wastewater treatment. The performance of the integrated electrocoagulation process in the FABR (E-FABR) was also investigated. The large benchscale five of sectional FABR reactor was assessed continually to the hydraulic retention times (HRTs) of 40, 30, and 20 h, respectively to meet the effluent disposal standards using the HDPE-2H media in the FABR. After determining the optimum HRT, EP was integrated in 4th section of the FABR to improve the performance. At the E-FABR, the steel-steel and aluminum electrode pair (Al-Al) was evaluated at the current densities of 0.05-0.5 mA/cm2 (HRT=20 h). The performance of FABR decreased with reduced HRT from 40 to 30 and 20 h. At the optimum HRT (30 h), the reactor met the TSS, COD, and BOD effluent discharge standards. The mean steady-state removal of TSS, COD, BOD5, total nitrogen, and total phosphorus was 93±0.5, 91±0.8, 93.4±1, 16±1, and 28±0.7%, respectively. The E-FABR with the steel and aluminum electrodes at the current densities of 0.3 and 0.1 mA/cm2 and HRT of 20 h decreased the TSS, COD, BOD, SO4, and TP concentrations to the effluent discharge standard limits. Therefore, the FABR is an efficient system for municipal wastewater treatment, and E-FABR with aluminum electrodes and extremely low current density could easily treat wastewater to the effluent discharge standards.