Sewage concentration via a graphene oxide modified thin-film nanocomposite forward osmosis membrane: Enhanced performance and mitigated fouling

Abstract

• The GO modified TFN-FO membrane shows improved filtration performance. • The GO modified TFN-FO membrane shows an enhanced antifouling property. • The GO modified FO membrane has high and stable sewage concentration performance. • High water flux recovery rates can be achieved by simple membrane cleaning. Upstream intensification of wastewater pre-treatment could improve the efficiency of the biological wastewater treatment process by separating and concentrating the organic matter. Forward osmosis (FO) technology is a potential upstream intensification strategy for sewage concentration. Herein, a high-performance graphene oxide (GO) modified TFN-FO membrane was fabricated and evaluated. The GO modified TFN-FO membrane showed 41% enhancement in water flux without weakening the selectivity property, due to the improved membrane hydrophilicity, thinner polyamide layer and facilitated water transportation by GO. The enhanced filtration performance and antifouling property of the TFN-FO membrane were confirmed by using simulative foulant solution and raw sewage as feed solutions. Moreover, a 41 h semi-continuous filtration experiment was conducted for sewage concentration using real raw sewage as the feed solution. Results indicated that the TFN-FO membrane achieved 4.6 times sewage concentration with high rejection of ammonia, nitrogen and organics. In addition, with a simple in-line water cleaning-in-place (CIP) process, most of the pollutants could be washed off from the surface of the TFN-FO membrane in 15 min and ~ 90% water flux could be recovered after each cleaning cycle. This work demonstrates the potential application of TFN-FO membranes for sewage wastewater concentration.