Chemical and Electrocoagulation for Chromium (VI) Removal from Galvanic Effluents

Susarla Venkata Ananta Rama Sastry

Abstract

Industrial effluents usually contain 10 to 500 mg/l Cr(VI); that according to internationalenvironmental rules must be set at permissible levels before being discharged into the environment.The upper permitted levels of chromium are 0.5 mg/l for effluent discharge and 0.01 mg/l for drinkingwater respectively. Hexavalent chromium is a very toxic heavy metal moiety occurring in variousindustrial wastewaters, such as electroplating, anodizing, tanning and dyeing effluents. Industrialeffluents may contain hundreds of mg/l of Cr(VI), whereas the upper allowed limit for effluentdischarge to aquatic systems is 0.5 mg/l. In the present study, the removal of chromium fromindustrial electroplating effluents is presented using the chemical coagulation with addition of ironsulfate coagulant and the electrocoagulation process with iron electrodes. Both processes achieved arapid and effective chromium removal of over 99.9%, with the electrochemical process being superiorin terms of the total operational costs.

Abstract

Keywords