Electrocoagulation of palm oil mill effluent treatment

Abstract

Palm oil mill effluent (POME) categorized as highly polluted wastewater. The conventional methods have limitations. Electrochemical process offers several advantages however the previous study on the electrode material such as aluminum and iron show removal rate lower than 50%. Thus, this study investigates the electrochemical process of POME treatment using platinum and graphite as anode materials after the selection process. Response surface methodology was used to study the effect between different operating conditions such as voltage, electrolysis time and electrolyte support and responses of the treatment including chemical oxygen demand (COD) removal, colour reduction and electrolyte support. A quadratic mathematical model was developed for all responses using Box-Behnken Design (BBD) with R2 0.9853 for COD removal, R2 0.9478 for colour reduction and R2 0.9185 for oil and grease removal on platinum as anode material. Meanwhile R2 0.9844 for COD removal, R2 0.9412 for colour reduction and R2 0.9724 for oil and grease removal. According Derringer’s function desirability, under the optimum condition such as voltage 15 V, electrolysis time 2 hours and 19.95 mg/L NaCl of POME treatment using platinum could achieve 84±2% COD removal, 98±2% colour reduction and 99±1% oil and grease removal. For graphite material under optimized conditions such as voltage 14 V, electrolysis time of 3 hours and electrolyte amount of 13.41 g/L show that electrochemical process achieve 56±4% COD removal, 65±1% colour reduction and 94±2% oil and grease removal. The total operating cost both for platinum and graphite under optimum conditions are US$ 18.346/L and US$16.6641/L of treated POME. On the other hand, the operating cost for conventional method US$ 6.63/L of POME with drawback 50% removal of COD and requires more than 24-hour retention time. These results indicate the platinum and graphite as anode material is applicable and effective for POME treatment.