REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER BY GRANULAR FERRIC HYDROXIDE

Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide from water at pH <= 7 and in 90 min contact time. Maximum adsorption of sulfate and chloride had been specified in this study, the interfering effects of these two anions had not been detected in concertrations of 200 and 400 mg/L. The absorbability of hexavalent chromium by granular ferric hydroxide could be expressed by Freundlich isotherm with R-2>0.968. However, the disadvantage was that the iron concentrantion in water was increased by the granular ferric hydroxide. Nevertheless, granular ferric hydroxide is a promising adsorbent treatment can easily be accomplished and removal of excess iron is a simple practice for conventional water treatment plants. Thus, this method could be regarded as a safe and convenient solution to the problem of chromium-polluted water resources.