Evaluation of forward osmosis membrane performance by using wastewater treatment plant effluents as feed solution

Currently, there is a growing emphasis on seawater desalination and wastewater reuse around the world. Reverse osmosis (RO) is typically used for both seawater desalination and wastewater reuse. As an alternative technology of RO, forward osmosis-reverse osmosis (FO-RO) hybrid system has recently attracted attention. To select suitable membrane and feed water for this process, the performance of forward osmosis (FO) membrane according to the types of membrane and feed water quality was evaluated in this study, including three types of FO membrane (membrane I/II/III) and three types of feed water (1st/2nd/3rd wastewater treatment plant effluents, WWTP Efs). Despite high structural parameter, membrane II showed the highest water permeability (5.37LMH/bar) with highest water flux (around 27.1LMH) using draw solution of 0.5M NaCl (feed solution: 5mM NaCl). In fouling test, there was severe water flux decline when 1st WWTP Ef was used as feed solution compared to the case when 2nd/3rd WWTP Efs was supplied. Membrane III showed higher fouling resistance due to its chemistry characteristic compared to membrane I or II. Due to complex feed water characteristics, FO reversibility was lower compared to that of a previous study. Therefore, to optimize FO-RO hybrid system, FO membrane performance should be tested with different membrane characteristics and feed water qualities to develop suitable cleaning or pretreatment method and strategy to increase the reversibility of membranes.