forward osmosis-challenges and opportunities of a novel technology for arsenic removal from groundwater

Forward Osmosis (FO) represents a innovative membrane technology for liquid separation driven by the osmotic pressure of aqueous solutions. This work studied at laboratory scale commercial FO membranes regarding water flux, reverse salt diffusion as well as As(III) and As(V) rejection. The findings showed that As(V) is significantly better rejected than As(III) what is in agreement with the findings on Reverse Osmosis (RO) and Nanofiltration (NF) membranes. Since FO has to be operated as combined process with regeneration of the draw solution (e.g. RO) eventually rejection is higher due to the second barrier. Hence FO may offer an alternative solution with lower energy consumption for conventional two stage membrane processes (RO, NF).