Removal of dissolved organics from produced water by forward osmosis

This study investigated the performance of the forward osmosis (FO) process for treating produced water. Water permeate flux and reverse salt flux (RSF) were examined at different feed pH values and operating configurations (i.e. FO, pressure retarded osmosis (PRO), and reverse osmosis (RO) modes). Acetic acid was selected as a model organic acid to present the dissolved organic fraction in produced water. Results reported here indicate that only membranes specifically designed for FO applications can be used in the FO and PRO modes. Due to the internal concentration polarization phenomenon, the PRO mode resulted in a higher water permeate flux and RSF than those in the FO mode. Acetate rejection was pH dependent in both the FO and RO modes. Furthermore, in the RO mode, acetate rejections by the FO membranes were higher than their nanofiltration counterparts. Results reported here suggest that FO can be a viable treatment option for the removal of dissolved organics from produced water.