微电解絮凝耦合技术处理含重金属铅锌冶炼废水

Treatment of zinc and lead smelting wastewater containing heavy metals by combined process of micro-electrolysis with flocculation

采用"石灰中和曝气微电解絮凝沉淀法"技术处理含重金属铅锌冶炼废水,考察微电解进水pH值、水力停留时间、铁炭质量比、絮凝pH值和助凝剂用量等反应条件对废水中铅、锌、镉、铜和砷离子去除率的影响。采用扫描电镜(SEM)和能谱(EDS)等测试手段,研究微电解反应前后铁屑和活性炭的表面形貌及物质组成的变化,分析铁炭微电解原理及铁炭床失效原因。结果表明:在微电解铁炭质量比为1:1.5、进水初始pH值为2.5、水力停留时间为40 min、絮凝pH值为11、助凝剂PAM用量为4×10 6(质量分数)的条件下,微电解絮凝耦合技术对废水中各离子的去除效果最佳,Cd2+出水浓度达到了《污水综合排放标准》(GB8978—1996)中的一级标准,Pb2+、Cu2+、Zn2+和总砷的出水浓度满足《地表水环境质量标准》(GB 3838—2002)中Ⅲ类水标准。

The combined process of ＂lime neutralization-micro-electrolysis-flocculation＂ was used to treat lead and zinc smelting wastewater containing heavy metal ions.The influence of the experimental conditions on the removal rate of Pb^2＋,Zn^2＋,Cd^2＋,Cu^2＋ and As ions in the wastewater was also investigated.The experimental conditions included the mass ratio of Fe to C,initial pH of the infall wastewater,and hydraulic retention time for the micro-electrolysis reactions,and pH and dosage of PAM flocculant for following flocculation reactions.The morphology and compositions of the carbon and iron surface were also characterized by SEM and EDS before and after the treatment of the micro-electrolysis reaction,the reaction mechanism of Fe/C micro-electrolysis and the invalidation cause of Fe/C wadding were analyzed.The results show that the optimal conditions of the micro-electrolysis-flocculation are the mass ratio of Fe to C of 1：1.5,initial pH 2.5 and reaction time 40 min for the micro-electrolysis reactions,and pH 11 and dosage of PAM of 4×10-6（mass fraction） for flocculation reaction,under which the combined technique has the highest removal efficiency for the heavy metal ions in this wastewater.Cd2＋concentration in the outlet wastewater satisfies the primary standard in 《Integrated Wastewater Discharge Standard》（GB8978—1996） in China,and the concentrations of Pb2＋,Zn2＋,Cu2＋ and As ions satisfy the Ⅲ surface water standard of《Environmental Quality Standard for Surface Water》（GB 3838—2002） in China.