[Application of reverse osmosis technology for arsenic removal from drinking water]

ABSTRACT

Arsenic [As] is a highly toxic metalloid found in ground and surface waters. Arsenic contamination in drinking water leads to harmful effects on human health. In this study, the efficacy of Reverse Osmosis [RO] membrane technology was evaluated for arsenic removal from drinking water. This experimental study was carried out on RO membrane spiral- wound module [model 2521 TE, CSM Co. Korea] in pilot scale. After preparation of sodium arsenate solution in the laboratory, performance of RO membrane system in arsenic [As] removal was investigated. Experiments were conducted with five different pressures [100, 130, 160, 190, 210 Psi], pH [4, 5.5, 7, 8.5, 10], temperature [20, 25, 30, 35, 40°C] and an initial As concentration of 0.2 mg/L. The influence of different feed concentrations [0.2, 0.5, 1, 1.5, 2 mg/L] on As removal efficiency was also examined. In each step, flux was measured and after 30 minutes samples were taken. Arsenic amount in feed and permeate were measured by silver diethyldithiocarbamate [AgDDTC] method. The results of this study demonstrated that greater than 90% of As can be eliminated from drinking water. Also the results showed that the pressure of 190 psi, As concentration of 0.2-0.5mg/L, temperature of 25-30°C and pH = 6-8 were the optimal conditions. Arsenic removal efficiency in optimal conditions of system performance was up to 99%