PROCESS AND PLANT FOR CHROME REMOVAL FROM HEXAVALENT CHROME-CONTAINING WASTE WATER

摘要

The invention relates to a process and a plant for chrome removal from waste water having a content of 1...100 mg/l of Cr(VI). According to the invention, the process consists in reducing the hexavalent chrome to trivalent chrome with iron cuttings, at a contact time of 1...2 hours, at a pH value of 2 and 2.5, respectively, after which the effluent is brought with 30% NaOH to a pH of 8.3 within a basin where it is left to settle for 5 hours, the clarified treated water being finally within the maximal limits admitted for it to be discharged into the sewage systems. The plant claimed by the invention comprises a pH correcting basin (), an activation/reactivation/reduction column () with iron cuttings filler and a settling-clarifying basin ().