Cleaning efficiency of the fouled forward osmosis membranes under different experimental conditions

Forward Osmosis (FO) has been attracting increasing attention due to the advantages that offers when compared to other desalination processes. In our previous study, influence of different parameters on the performance of diluting seawater through wastewater reuse was successfully investigated. In the FO and reverse osmosis (RO) hybrid process, FO membrane fouling is one of the critical issues. In this study influence of various operating conditions (DS concentration, FS pH, crossflow rates and pressure) on fouling behavior and cleaning efficiency were extensively evaluated. The synthetic wastewater (SWW) that simulates effluent organic matter and generally found in the biologically treated sewage effluent (BTSE) was used as FS. At higher FS pH the system attaints the maximum membrane-particle interaction by formations of the small aggregates that promote membrane fouling with lower cleaning efficiency. Different cross-flow rates showed a big influence on membrane fouling and cleaning behavior. By rising flow rate from 400 mL/min to 700 mL/min the generated shear forces cause less deposition and higher cleaning efficiency of the FO membrane. Membrane materials play an important role in membrane-particle interactions consequently on controlling membrane fouling and cleaning behavior in the FO process. Moreover, the elevated DS concentration boosts fouling of the FO membrane and diminishes cleaning efficiency.