Improvement of anaerobic biological treatment effect by catalytic micro-electrolysis for monensin production wastewater

Monensin discharged with the animal wastes and wastewater can cause harmful effect to the environment and human health. In this study, catalytic micro-electrolysis (CME) reactor filled with novel catalytic-ceramic-filler was utilized as pretreatment to improve the anaerobic biological treatment effect for the real monensin wastewater. The CME reactor as a possible pretreatment process had satisfactory effect, with 98.44% of monensin residue and 37.07% of chemical oxygen demand (COD) removals at the optimum hydraulic retention time (HRT) of 3.0 h and dissolved oxygen (DO) of about 1.5 mg L−1. Subsequently, as the secondary biological treatment, the Up-FLOW Anaerobic Sludge Blanket (UASB) reactor treatment effect was greatly improved by the CME pretreatment, with approximately 80% of COD removal at the optimum organic loading rate (OLR) of 3.5 kg m−3 d−1, which had higher methane yield (about 0.33 m3 kg−1 COD−1) and lower volatile fatty acids (VFA) concentration (about 300 mg L−1) than that of the UASB reactor without pretreatment. Finally, an activated sludge (AS) reactor was utilized as the last biological treatment and the coupled CME-UASB-AS system had high COD and chroma removal (about 98% and 95%, respectively), the final effluent (COD and chroma of about 200 mg L−1 and 40, respectively) with no residual monensin met the national discharged standard, which provided a reliable system for the practical monensin production wastewater treatment.