Pressure-driven and thermally-driven membrane operations for the treatment of arsenic-contaminated waters: A comparison.

The presence of arsenic in water beyond the admitted limits is becoming an important concern for many Countries. Methods usually employed for the arsenic removal from water are based on coagulation followed by filtration, ion-exchange, adsorption. Drawbacks like the use of chemicals and the production of sludges (in case of coagulation) have, however, to be mentioned. Membrane operations, based on the features of membrane materials involved in the separation, do not need chemicals and are easy to scale-up, due to their modularity. In this contribution, the potential of membrane operations for the treatment of arsenic-polluted water is presented and discussed. In particular, two classes of membrane operations are illustrated and compared, the pressure-driven, like Nanofiltration (NF) and Reverse Osmosis (RO) and the thermally-driven ones, like Membrane Distillation (MD).