Explore the forward osmosis performance using hydrolyzed polyacrylamide as draw solute for dye wastewater reclamation in the long-term process

The long-term (50 h) performance using hydrolyzed polyacrylamide (HPAM) as draw solute for dye wastewater reclamation in forward osmosis (FO) process has been investigated. The paper focused on the long-term flux patterns and membrane fouling propensity in different modes of membrane orientation. Comparing with the FO mode, the pressure retarded osmosis (PRO) mode showed more severe fouling, in which the water flux-time curve had three-stage. The combination of different membrane orientations was in favor of build-up of foulants at the membrane surface, which was hard to clean up just using physical methods. Furthermore, the dye rejection characteristics of TFC-FO membrane, the effects of physical cleaning on membrane flux recovery and the viscosity of the diluted HPAM solution were also measured. Comparing the performance of all the different modes, the FO mode was proven to be the best candidate among all the membrane orientation modes, which showed the highest dye rejection (nearly 1), largest viscosity of the diluted HPAM solution (93.3 mPa s), most effective physical cleaning (almost 100%) and least fouling. In all, it was feasible to apply FO process to treat the dye wastewater using HPAM as draw solute in the long-term process. To be specific, the diluted HPAM solution after FO process could be used directly to polymer flooding in many oilfields to increase oil production, and at the same time, the dyeing wastewater could be well concentrated.