Treatment of Chromium-containing Wastewater

We mainly use chromium reduction method to treat wastewater containing hexavalent chromium. The principle of this method is to reduce hexavalent chromium to trivalent chromium by adding reducing agents such as ferrous sulfate, sodium sulfite, sodium bisulfite and sulfur dioxide under acidic conditions, and then add sodium hydroxide, calcium hydroxide and lime to adjust the pH value so as to form trivalent chromium hydroxide precipitation to separate from wastewater.

The pH value was adjusted to 2.5-3 by adding sulphuric acid and reducing agent. The reaction end point was controlled at 300-330 MV by ORP instrument. The reaction time was about 15-20 minutes. Stirring can be done by mechanical stirring, compressed air stirring or hydraulic stirring.

Control conditions of coagulation reaction:
PH value: 7-9, reaction time: 15-20 minutes.