Pilot-scale experiments on a hybrid membrane-electrocoagulation system to produced water treatment in a domestic oil reservoir

The goal of this paper is to design and set up a new hybrid treatment system for purification of Iranian offshore oil company wastewater. The treatment system consists of electrocoagulation, microfiltration and reverse osmosis (RO) sections. Treatment performance is evaluated by measuring electrical conductivity (EC), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total suspended solids (TSS), total dispersed solids (TDS) oil and grease (O&G), total hardness (TH) and turbidity. Results showed that the maximum removal efficiency of BOD5, COD, TSS, O&G, EC, TH and turbidity were obtained as 94.49%, 92.17%, 88.18%, 80.8%, 89.84%, 86.66% and 71.72%, respectively. DO was increased significantly due to the reduction of BOD, COD and microorganisms. Results showed that the combination of iron and aluminium electrodes can be very effective in removing pollutants. In addition, the use of microfiltration before RO led to a significant reduction in salinity and TDS. Response Surface Methodology (RSM) was used to determine the optimal experimental conditions for COD, BOD5 and turbidity using Design Expert11. RSM results showed that the optimal electric current and time for BOD5 and COD removal is 20A and 300 min, respectively. The optimal electric current and time for turbidity were obtained as 20A and 210 min.