A hybrid electro-coagulation/forward osmosis system for treatment of produced water

Abstract

Oil and gas exploration produce large volumes highly contaminated produced water (PW) which exhibits a major environmental challenge. This work investigates the application of a novel hybrid system by combining electro-coagulation and forward osmosis (FO) for the treatment and reclamation of PW. Electro-coagulation was applied at three different current densities 10, 30 & 60 mA/cm2 for 10 and 30 min. The treated produced water was further treated by Forward Osmosis (FO) using polymeric membrane. Two orientations of the membranes (active layer facing draw solution and active layer facing feed solution) and three flow rates 0.8, 1.2 and 2 LPM were tested. By applying electro-coagulation, the optimum water quality was obtained after 10 min run time, at a current density of 10 mA/cm2. Electro-coagulation achieved 91% and 97% removal of total organic carbon (TOC) and oil and grease (O&G), respectively. FO used in pressure retarded osmosis (PRO) mode achieved the highest flux at a flow rate of 1.2 LPM and reduced the PW conductivity by 16%. Overall, the hybrid system attained a total of 99% removal of total suspended solids (TSS). The obtained improved water quality suggests practicability of the applied hybrid system in the treatment and reclamation of PW. - 2019 Elsevier B.V.