Use of reverse osmosis for removal of chromium from electroplating industrial sewages

Chromium is a transitional element of group 6 and is the 21rst common element in the nature which occurs in two forms: a three valent and a 6 valent form. Electroplating industry contributes much to the pollution of the environment. The aim of this study was to evaluate the efficiency of reverse osmosis membrane in the removal of chromium from industrial sewages. We also studied the optimum condition for reverse osmosis membrane for removal of chromium. At first, synthetic chromium solutions with concentrations of 5, 10, 15, 20 g/l were prepared and injected into the spiral module of 2521 TE model RO system made in Korea by CSM Company. The influence of operating pressure, feed concentration, temperature, and pH on chromium removal efficiency for each concentration was determined. Our study revealed that a 200psi pressure (α=0.01), 10 g/l concentration (α=0.05), 25˚C temperature (α=0.05) and a pH of 6-7 gave rise to the optimum condition for removal chromium. The efficiency of chromium removal by reverse osmosis membrane was about 99%. Therefore this method of chromium removal, when compared to other methods, is more suitable and effective.