Hexavalent chromium was reduced to trivalent chromium by sodium bisulfite (NaHSO3) at pH 2~3. Then adding flaky alkali or lime to generate hydroxide precipitation; Or use a heavy metal trapping agent, which is also removed by precipitation. Add PAM and PAC to help precipitate. . .

When the pH value is about 10, nickel can be directly removed by adding alkali or recapture agent.

The price of hydroxide precipitation method is slightly lower and it is widely used, but this method has poor removal effect and is not easy to meet the standard; Using heavy metal trapping agent, the method is simple and the removal effect is good, but the price is slightly higher.