Dompé Ghislain Ahoulé^1,, Franck Lalanne²

The influence of operating conditions on the performance of nanofiltration (NF270) and reverse osmosis (TW30) membranes for arsenite [As (III)] removal was studied. This study aimed at following the evolution of membrane performance, especially, solute rejection and water flux with the change of operating parameters. The operating parameters as applied pressure, recovery, feed pH, feed As (III) concentration and ionic strength were considered. As (III) rejection and water flux were determined at each operating condition. Results show that increasing applied pressure contributes to improve As (III) rejection and water flux through the membrane. As (III) rejection increased from 40.2 to 71.1% and water flux from 11.65 to 38.59 Lh^-1m^-2 when applied pressure changed from 2 to 6 bar with TW30 membrane. In the same sense, an increase of pH at a value of 10 considerably improves As (III) removal whereas water flux was slightly impacted. On the other hand, an increase of recovery and feed As (III) concentration leads to the decrease of the system performance in term of As (III) rejection. As for ionic strength, its increase does not affect As (III) rejection but can contribute to the decrease of water flux. It was put in evidence that applied pressure and feed pH are the most important parameters which must be considered if As (III) removal wants to be improved.

As (III) rejection, nanofiltration, reverse osmosis, operating parameters