Arsenic removal from drinking water by direct contact membrane distillation

Abstract

In this study, the treatability of arsenic (As) contaminated water by direct contact membrane distillation (DCMD) at different delta temperatures (Delta T) 30, 40 and 50 degrees C has been investigated. Two different pore sizes (0.22 mu m and 0.45 mu m) of hydrophobic membranes made of polyvinylidene fluoride (PVDF) were used. The membrane pore sizes, the operating temperatures, the feed solution As concentration and conductivity have been varied during the experimental tests to follow the removal efficiency and flux behavior. Both membranes tested had high removal efficiency of arsenite (As (III)) and arsenate (As (V)) and all permeates presented As concentration far lower than recommended 10 mu g/L of world health organization (WHO). As concentration was below detection limit in many permeates. Conductivity reduction efficiency was over 99% and the transmembrane flux (TMF) reached 19 L/m(2). h at delta temperature (Delta T) of 50 degrees C with PVDF 0.45 mu m membrane. The experimental results also indicated that 0.45 mu m pore sizes PVDF membranes presented higher flux than 0.22 mu m pore sizes membranes. Regardless of all operating conditions, highest fluxes were observed at highest Delta T (50 degrees C).