Comparison of electrocoagulation, peroxi-electrocoagulation and peroxi-coagulation processes for treatment of simulated purified terephthalic acid wastewater: Optimization, sludge and kinetic analysis

Abstract

This study mainly focuses on a comparative study of electrocoagulation (EC), peroxi-electrocoagulation (PEC) and peroxi-coagulation (PC) processes for the treatment of aqueous solution containing major toxic components of purified terephthalic acid wastewater: benzoic acid (BA), terephthalic acid (TPA), para-toluic acid (p-TA) and phthalic acid (PA). The solution was initially treated by acid treatment method at various pH (2-4) and temperature (15-60 °C). The supernatant was further remediated by EC, PEC and PC methods independently. Process variables such as pH (4-12) and pH (1-5), current density (45.72-228.60 A/m2), electrolyte concentration (0.04-0.08 mol/L), electrode gap (1-3 cm), H2O2 concentration (600-1,000 mg/L) and reaction time (20-100 min) during EC, PEC and PC treatment were effectively optimized through central composite design under Design Expert software. Maximum COD removal of 60.76%, 73.91%, 66.68% with energy consumption (kWh/kg COD removed) of 95.81, 49.58, 69.26 was obtained by EC, PEC and PC treatments, respectively, at optimum conditions. Electrochemical methods were compared by removal capacities, consumption of energy, operating cost, degradation kinetics and sludge characteristics. PEC treatment was found most effective among EC, PEC and PC processes due to its highest removal capacity and lowest energy consumption features.