Implications of advanced wastewater treatment: Electrocoagulation and electroflocculation of effluent discharged from a wastewater treatment plant

Abstract

In this research, wastewater treatment was inspected on a pilot-scale wastewater treatment plant by electrochemical techniques, electrocoagulation (EC), electroflotation (EF) and electrophoretic deposition (EPD). The wastewater samples have been characterised by applying different parameters to determine optimum working conditions of the electrocoagulation reactor. Two electrodes have been tested separately with an outflow coming from primary and secondary sedimentation tank. The outflows from these tanks are introduced in EC reactor then EC reactor efficacy is determined for the removal of chemical oxygen demand (COD), suspended solids, micropollutants and amount of coagulants in agglomerates at different current densities. The amounts of suspended solids (SS) in influent and effluent streams were determined by the membrane filtration technique. The operational applied current values range from 1–4 A in the case of COD removal by Fe and Al. While for SS aggregation the applied current ranges from 0.5–3 A and inflow rate was tested from 250 to 500 L/h. The pH of outflows increased by increasing applied current and both of these parameters were found a positive increase in the amount of SS aggregations after EC treatment. Furthermore, the COD removal efficiency was found to be 56–57 % and 12–18 % in case Fe and Al electrode respectively after EC treatment. The results showed that applied current is the most effective parameter, whereas the aluminium electrodes have produced more amounts of flocs and bubbles in comparison to iron electrodes at similar amount of current density.