Abstract
Simultaneous removal of oil droplets and hexavalent chromium from synthetic wastewater of chromium plating and chromate conversion coating plants by electrocoagulation in a new cell design was studied under different conditions of pH, initial Cr6+ concentration, NaCl concentration, and current density. Under optimum conditions, more than 90% of oil content and Cr6+ were removed. Percent removal was found to increase with decreasing Cr6+; high Cr6+ concentrations tend to passivate the aluminum anode and decrease the percent removal of Cr6+ and oil. The effect of NaCl concentration shows a maximum percent removal at 1.5%. The pH range 4-5 was found to give the highest percent removal. Increase of current density was found to improve the percent removal of Cr6+ and oil droplets. The favorable effect the combined oil and Cr6+ removal on the capital and operating costs of wastewater remediation was pointed out. Potential merits of the present cell design compared to the traditional parallel plate cell were highlighted.