铁盐沉淀-絮凝法处理矿山低浓度含砷废水

采用铁盐沉淀-絮凝法处理某矿山低浓度含砷废水,研究了沉淀剂种类、铁与砷的摩尔比(铁砷比)、砷的价态、反应pH以及添加高分子絮凝剂对除砷效果的影响。与其他铁盐沉淀剂(聚合硫酸铁、氯化铁)相比,高铁酸钾具有优异的除砷性能。铁盐对砷(Ⅲ)的去除率明显低于砷(Ⅴ)。砷去除率随铁砷比的增大而提高。反应pH对除砷效果影响显著。以高铁酸钾为砷沉淀剂,在铁砷比为12∶1、反应pH为5~7、聚丙烯酰胺投加量为0.5~1.0 mg/L的最适条件下,废水的砷去除率达98%以上。处理后出水中砷质量浓度低于0.05 mg/L,达到GB3838—2002《地表水环境质量标准》中Ⅲ类水质标准。

Treatment of low concentration arsenic-containing mine wastewater by iron salt precipitation-flocculation process

The low concentration arsenic-containing mine wastewater was treated by iron salt precipitation-flocculation process. The factors affecting As removal were investigated,such as：the type of precipitant,the mole ratio of Fe to As（Fe/As）,the valence of As,the reaction pH and the addition of polymer flocculant. Compared with polymeric ferric sulfate and ferric chloride,potassium ferrate had excellent performance to As removal. The removal rate of As（Ⅲ）was more less than that of As（Ⅴ）by iron salt. The As removal rate was increased with the increase of Fe/As. The effect of reaction pH on As removal was significant. Under the optimum conditions of using potassium ferrate as precipitant,Fe/As 12,reaction pH 5-7,polyacrylamide amount 0.5-1.0 mg/L,the As removal rate reached over 98%. The mass concentration of As in the effluent was below 0.05 mg/L,which met the third grade standard of GB 3838-2002.