Forward Osmosis Polysaccharide Fouling: Effect of Solution Viscosity and Foulant Deposit Resistance

In recent years, forward osmosis (FO) has been attracting an intensive research interest due to its potential for low-energy water desalination and wastewater treatment. Membrane fouling, especially that caused by polysaccharides, has been regarded as one of the significant challenges retarding the development of FO process in various applications. In order to efficiently alleviate polysaccharide fouling in FO separation, it is necessary to strengthen the fundamental understanding on its mechanisms. This study systematically investigated the fouling behaviors of different polysaccharides, namely alginate, xanthan and pullulan, in FO. The three selected model foulants behaved differently; specifically the polysaccharide solution of high viscosity in the presence of calcium ions are likely to lead to severe membrane fouling, due to adsorption and accumulation of the polysaccharide on the membrane surface.