Electrochemical treatment of simulated industrial paint wastewater in a continuous tubular reactor

The electrochemical treatment of industrial water-based paint wastewater was investigated in a continuous tubular reactor constructed from a stainless steel tube with a cylindrical carbon anode. Industrial wastewater was prepared by thinning a commercial paint down to 4.4% (w/v) with water, which is the solid material content of the wastewater generated in the paint manufacture. The effects of residence time on chemical oxygen demand (COD), color and turbidity removals and pH change was studied at 30 °C, 35 g/L electrolyte and 7496 mg/L COD feed concentrations with 66.8 mA/cm2 current density. The optimum residence time in the reactor was determined 6 h for a cost driven approach, enabling COD, color and turbidity removal as 44.3%, 86.2% and 87.1%, respectively, and a discharge pH value of 7.33. At 6 h of residence, 42 kWh energy was consumed per kg COD removed maintaining a mass transfer coefficient value of 3.62 × 10−6 m/s. In all runs, the polymer/water emulsion always broke into insoluble solid particles during the electrochemical treatment, which eventually precipitated.