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 inmeeting drinking water standards. for this study, granular ferric hydroxide was used as adsorbent forremoval of hexavalent chromium. besides, the effects of changing contact time, ph and concentrations ofcompetitive anions were determined for different amounts of granular ferric hydroxide. it was found thatgranular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from water at ph<7and in 90 min contact time. maximum adsorption capacity was determined to be 0.788 mg cr+6fg granularferric hydroxide. although relatively good adsorption of sulfate and chloride had been specified in thisstudy, the interfering effects of these two anions had not been detected in concentrations of 200 and 400mg/l. the absorbability of hexavalent chromium by granular ferric hydroxide could be expressed byfreundlich isotherm with r2>o.968. however, the disadvantage was that the iron concentration in waterwas increased by the granular ferric hydroxide. nevertheless, granular ferric hydroxide is a promisingadsorbent for chromium removal, even in the presence of other interfering compounds, because granularferric hydroxide treatment can easily be accomplished and removal of excess iron is a simple practice forconventional water treatment plants. thus, this method could be regarded as a safe and convenientsolution to the problem of chromium-polluted water resources.