Comparing Chemical Coagulation and Electrocoagulation on removal efficiency of Chromium (VI) from Galvanic Effluents

Abstract

Hexavalent chromium is a very toxic heavy metal moiety occurring in various industrial wastewaters, such as electroplating, anodizing, tanning dyeing effluents.Industrial effluents may contain hundreds mg/L of Cr(VI), whereas the upper allowed limit for effluent discharge to aquatic systems is 0.5 mg/L.In the present study, the removal of chromium from real electroplating effluents is presented using the chemical coagulation with addition of iron sulfate coagulant and the electrocoagulation process with iron electrodes.The optimal affecting parameters for the chemical coagulation process were found to be solution pH 11 and coagulant dose 500 mg/L, whereas for electrocoagulation pH 11 and applied current density 15 mA/cm2.Both processes achieved a rapid and effective chromium removal of over 99.9 % with the electrochemical process being superior in terms of total operational costs.