A Study on Artificial Hexavalent Chromium Removal by Using Zero Valent Iron Reactor and Sand Filter in Electrochemical Reduction Process

Abstract

Hexavalent Chromium (Cr(IV)) is found in industrial discharges and must be removed before being discharged into receiving waters. Removing Cr(VI) means removing risk of cancer and other ill-health effects associated with it. This research describe column experiment in laboratory which quantify the rate of Cr(VI) removal by zero valence Ion (ZVI) reactor and sand filter from an artificial Cr(VI) waste-water using electrochemical reduction process. The main goal for this study are to study the effectiveness of ZVI in removing Cr(VI) and sand filter for polishing Cr(VI) remaining in ZVI reactor. Test of Cr(VI) were conducted under the following conditions: Cr(VI) concentration for experiments 1, 2, 3 and 4 for feed solution in 1–10 mg/l range; 3 cases of column experiment; The flow rate decided is 2 ml/min and pH adjusted at 7.7 for the feed solution. Three cases of column experiment are column ZVI (1 column), Column ZVI and Sand Filter (2 columns) and Column ZVI mixed with sand (1 column). The result indicate ZVI reduces Cr(VI) to Cr(III) under alkaline conditions. The removal rate efficiencies for all of cases in range 80.33–100 %. The most effective experiment column (individually or in combination) has been chosen for removing Cr(VI) is Column ZVI and sand filter in two columns which is satisfied all of parameters (Cr(VI), iron total and pH) with standard of drinking and river water. The Cr(VI) removal attained for this two columns case is range from 99.8 to 100 %. In conclusion, All of the results in this case were found that the concentration of Cr(VI) effluent lower than the threshold limit 0.05 mg/l except for case of ZVI mixed with sand in one column.