Combination of novel coalescing oil water separator and electrocoagulation technique for treatment of petroleum compound contaminated groundwater

In the present study a combination of a novel coalescing oil water separator (COWS) and electrocoagulation (EC) technique was used for treatment of petroleum product contaminated groundwater. In the first phase, COWS was used as the primary treatment. Two different types of coalescing media and two levels of flow rates were examined in order to find the optimum conditions. The effluent of COWS was collected in optimum conditions and was treated using an EC process in the second phase of the research. In this phase, preliminary experiments were conducted in order to investigate the effect of EC reaction time and sedimentation time on chemical oxygen demand (COD) removal efficiency. Best conditions for EC reaction time and sedimentation time were obtained to be 5 min and 30 min, respectively. Response surface methodology was applied to evaluate the effect of initial pH, current density and aeration rate on settling velocity (V_s) and effluent COD. The optimum conditions, for achieving maximum values of V_s as well as the values of effluent COD, in the range of results were obtained at conditions of 7, 34 mA·cm⁻² and 1.5 L·min⁻¹ for initial pH, current density and aeration rate, respectively.