efficiency of removing chromium from plating industry wastewater using the electrocoagulation method

aims: chromium is one of the most important metallic pollutants in plating industry wastewater. this toxic metal is a serious threat to human health and to the environment due to its cumulative effects and non-degradability. this research intended to study the effects of ph, contact time, and voltage on the degree of chromium removal from wastewater of plating industry by using the electrocoagulation method. materials & methods: this laboratory research conducted from late may to late november 2012. a 1000cc reactor at laboratory scale was used that included 4 aluminum electrodes of 90% purity, dimensions of 5 by 10cm, and thickness of 1mm, with parallel arrangement. synthetic chromium-bearing wastewater was prepared at the initial concentration of 50mg/l. the process is done at ph values of 3, 7, and 9, electric potentials of 20, 30, and 40 volts contact durations of 20, 40, 60, and 80 minutes. findings: the degree of chromium reduction did not change linearly with time in the solution and strongly depended on the ph. the efficiency of chromium removal in the samples had an ascending trend with increases in voltage from 20 to 30 and 40 volts. the degree of chromium removal increased at longer contact times. conclusion: lower ph, more contact time and higher voltages are effective factors in the chromium removal from wastewater by coagulation method.