Removal of chromate from cooling tower blowdown by reaction with electrochemically generated ferrous hydroxide

Treatment of cooling tower blowdown with electrochemically generated ferrous hydroxide was found to reduce hexavalent chromium quantitatively to trivalent chromium which was precipitated without adjustment of the pH value. The final effluent contained less than 0.005 mg of hexavalent chromium per litre. The treatment also removed 80 per cent of phosphate and 40 per cent of total dissolved solids. The advantages and disadvantages of this method are indicated.