Removal of chromium (III) from wastewater by electrocoagulation method

The industrial wastewaters mostly contain toxic compounds such as chromium which would be harmful. Among the novel technologies for removing these pollutants, electrocoagulation can be considered as an effective method. This method enjoys some advantages like less amount of produced sludge and high efficiency in removal of pollutants. In this study, electrocoagulation method was used for the removal of chromium from synthetic wastewater polluted by chromium sulfate. For this purpose, the removal of chromium (III) with different concentrations from artificial wastewater was investigated. The best concentration was obtained at removal efficiency of 99.96%. A cubic tank made of Plexiglas with an effective volume of 2.5 L was used as electrocoagulation reactor. A total number of 10 metal plates made of iron in 11 x 7 cm and 2 mm thick were placed inside the tank. Electrodes of bipolar and monopolar array were also used in the reactor. The optimal values of pH, magnetic stirrer rotation, test time and settling times, temperature and voltage parameters were specified according to the primary concentration (500 mg/L). The optimal pH was 6. The mechanism of chromium removal was also investigated, and the results showed that the reactions in the electrocoagulation process are exothermic.