Superior Antifouling Capability of Hydrogel Forward Osmosis Membrane for Treating Wastewaters with High Concentration of Organic Foulants.

Wastewaters with high concentrations of organic pollutants pose a great challenge for membrane filtration due to their severe fouling propensity. In this study, a hydrogel forward osmosis (FO) membrane is explored for treating wastewaters of high concentration organic pollutants. This FO membrane has an ultrathin hydrogel selective layer, which is highly hydrophilic (water contact angle as low as 18°) and smooth (surface roughness <5 nm). Investigated with typical organic foulants (protein, alginate, humic acid, and oil) of high concentration (2000-20 000 mg/L), this hydrogel FO membrane exhibits remarkably superior antifouling capability, with its water flux decline ratio lower than a quarter that of commercial FO membrane under identical experimental conditions. The foulants on hydrogel membrane surface can be easily removed by simple physical cleaning without any chemical usage. At the same time, this hydrogel FO membrane achieves ∼2 times higher separation efficiency than commercial FO membrane in terms of specific water flux (JW/JS). The antifouling capability and separation efficiency of this FO membrane can be flexibly tailored during selective layer fabrication process. This study opens a new avenue for the treatment of high-strength organic wastewaters by developing a highly antifouling hydrogel-based FO membrane.