Removal of arsenic(V) by nanofiltration: Impact of water salinity, pH and organic matter

Climate change will affect water quality through a change in salinity, pH and organic matter (OM) content due to seawater intrusion, temperature change and subsurface biological processes. Therefore, a systematic evaluation of the impact of water quality variations is of particular importance to maintain the performance of a treatment process designed for drinking water. In this work, nanofiltration (NF) was investigated for the treatment of arsenic (As) contaminated water with the emphasis on water chemistry. Water salinity variations had no impact on the high rejection of As(V) with the studied NF membranes (NF270, NF90). The pH affects speciation and this significantly influenced the rejection of As(V) with NF270 (10-86%). The predominant mechanism was charge exclusion, while no effect was observed with NF90 (85-94%) where size exclusion plays the major role in rejection. The presence of humic acid (HA) in water has enhanced the rejection As(V) overall (10-20%) depending on water chemistry (pH, salinity) and membrane type. This study showed that NF technology was effective for As(V) rejection from water where seasonal changes in water quality can occur.