Evaluation of electrocoagulation process for high-strength swine wastewater pretreatment

Characterized by the high concentration suspended solids (SS), chemical oxygen demand (COD), biological oxygen demand (BOD), ammonium nitrogen and total phosphorus (TP), a solid-liquid separation as a pretreatment is mandatory for swine wastewater before biological treatment. In this study, batch tests of electrocoagulation were investigated under different structural parameters (anode material, inter-electrode distance) and operational parameters (current density, stirring speed, initial pH and reaction time). The results showed that the optimal conditions were the Fe anode, inter-electrode distance of 2.0 cm, current density of 30 mA/cm2, no stirring, initial pH of 6.3 without control and reaction time of 35 min in this study. By comparing with chemical coagulation, satisfactory performance was achieved under optimal electrocoagulation: supernatant recovery of 60%, SS, TP, COD and BOD removal efficiencies of 98.5%, 99.5%, 50.6% and 10%. In addition, fluorescent substances formation was observed under electrocoagulation and thus increased the BOD/COD ratio from 0.36 to 0.66. The enhanced biodegradability would facilitate the subsequent biological removal and the overall swine wastewater treatment. Conclusively, the iron electrocoagulation technology is a promising process for high-strength swine wastewater pretreatment.

Automated summary

By studying electrocoagulation under different conditions, it was found that satisfactory removal efficiencies can be achieved under specific operational parameters such as iron anode, 2.0 cm inter-electrode distance, and 30 mA/cm2 current density. Electrocoagulation also leads to the formation of fluorescent substances, increasing the biodegradability of wastewater, which facilitates subsequent biological treatment.