螯合沉淀法处理含铬电镀废水

Treatment of plating wastewater containing chromium by chelating precipitation

以NaHSO3为还原剂,新型重金属离子捕集剂DTCR为螯合剂,采用螯合沉淀法处理含铬电镀废水。研究了还原剂投加量、还原反应阶段的废水pH、螯合剂投加量、絮凝剂(PAM)投加量、螯合沉淀阶段的废水pH和搅拌时间对处理效果的影响。还原反应的较优工艺为:NaHSO3200mg/L,废水pH1.84,搅拌时间30min。螯合沉淀的最佳工艺条件为:DTCR70mg/L,PAM8mg/L,废水pH8.0,搅拌时间40min。采用最佳螯合沉淀工艺处理含铬电镀废水时,总铬去除率在95%以上,出水总铬为0.14mg/L,且未检测到其他重金属离子,可达标排放。

Plating wastewater containing chromium was treated by chelating precipitation method, using NaHSO3 as reductant and a heavy metal capturing agent DTCR as chelating agent. The influence of reductant dosage, wastewater pH at reduction reaction stage, chelating agent and flocculant （PAM） dosages, wastewater pH and stirring time at chelating precipitation stage on treatment effect was studied. The optimal process conditions of reduction reaction are as follows： NaHSO3200 rag/L, wastewater pH 1.84, and stirring time 30 min. The optimal process conditions of chelating precipitation are as follows： DTCR 70 mg/L, PAM 8 rag/L, wastewater pH 8.0, and stirring time 40 min. After the treatment of Cr-containing plating wastewater under optimal conditions, the total chromium in effluent is 0.14 mg/L with a total chromium removal rate not less than 95%, and no other heavy metal ions being detected, meeting the national discharge standard.