Removal of hexavalent chromium from ferrochrome dust effluent by chemical precipitation method

The dust produced by the electric arc method in the ferrochrome factory contains high amounts of hexavalent chromium, which has a high solubility in water and causes high environmental pollution. The present research has proposed a new method for neutralization of hexavalent chromium present in ferrochrome dust in solution environment by using chemical precipitation method. After checking conventional and non-conventional additives for neutralization by co-precipitation method, Iron sulfate is added to the aforementioned wastewater before release into the environment as a reducing agent of hexavalent chromium to trivalent chromium. Next, calcium sulfate was used as a stable complex forming factor in the system to remove chromium. XRD and XRF analyzes were used to characterize the dust and UV-Visible to determine the amount of chromium removed from the wastewater. The results showed that for ۱۰۰ g/l of dust dissolved in water, adding ۳۰ g of iron sulfate in the first stage and ۲۰ g of calcium sulfate in the second stage reduces the content of hexavalent chromium from high values to below ۱۰ ppm. Easy, high speed, cheapness and availability of additives are the merits of this method.

کلیدواژه ها:

Chromium removal ، Hexavalent chromium ، Co-precipitation ، Iron sulfate ، Calcium sulfate.