THE EFFECTS OF FERRIC IRON AND ORGANIC MATTER ON ARSENITE REMOVAL FROM WATER BY DIRECT CONTACT MEMBRANE

Abstract

The present study investigated the influence of ferric iron (Fe (III)) and organic matter (OM) on arsenite (As (III)) rejection from a synthetic contaminated water by direct contact membrane distillation (DCMD). Two different pore sizes (0.22 mu m and 0.45 mu m) of hydrophobic membranes made of Polytetrafluoroethylene (PTFE) were used at different feed temperature (40, 50 and 60 degrees C). The operating temperatures, the feed solution Fe (III) and OM concentration have been varied during the study to follow pollutants rejection efficiency and flux behavior. Fe (III) and OM concentration in the solution did not affect negstively As(III) rejection; both membranes used had high rejection efficiency and permeate arsenic (As) concentration was lower than recommended 10 mu g/L. As (III) concentration was below detection limit in many permeates. Fe(III) and OM contributed to higher rejection of As(III) and better transmembrane flux. Conductivity and As(III) was rejected up to 99%. In presence of Fe(III) and at feed temperature of 40 and 50 degrees C, As(III) was non-detectable in the permeate.