铁铝复配型混凝剂去除地下水高As(Ⅴ)试验

As(Ⅴ) Removal by Fe-Al Compound Coagulants in Groundwater

为建立完整的高砷地下水处理流程,在生物氧化滤柱实现了As （Ⅲ）至As（Ⅴ）的高效氧化后,进行了复配型混凝剂对As（Ⅴ）去除的最优条件筛选试验.在原水As（Ⅴ）的质量浓度为2.0 mg/L的条件下,铁铝复配混凝剂对As（Ⅴ）的去除性能较铁盐、铝盐等单—混凝剂投加量减少50％以上,且复配混凝剂强化了其对砷的吸附、沉淀性能及对絮体的沉淀及网捕卷扫功能,对于出水痕量砷,铝盐对于去除效果的提升作用更为明显,2种混凝剂交叉效应显著;采用5.0 mg/L三氯化铁和3.0 ～4.0 mg/L聚合硫酸铝2种混凝剂复合投加,除砷效果最好,出水As（Ⅴ）质量浓度稳定小于10.0000 μg/L;对复配型混凝剂最优条件的研究表明,在pH为6.00～7.00、浊度大于30.0 NTU或小于10.0 NTU时,复配混凝剂除砷效果最高,能稳定达到国家饮用水卫生标准（小于10 μg/L）.

To complete high quantity arsenic disposal process in groundwater, after As（ Ⅲ ） oxidized into As（V） by biological filter effectively, the optimal conditions for compound coagulants to remove As（Ⅴ） were conducted. Under the condition of As（Ⅴ） in the raw water of 2 mg/L, iron-aluminum compound coagulants were better than the single coagulant such as the iron salt or the aluminum salt for the removal of As （V）, which could save more than 50% adding. Besides, compound coagulants improved the absorption and sedimentation performance for As （V） and sedimentation performance for floc. For the trace of As（Ⅴ） in the effluent, Al played more important role in As removal and cross interaction for the two coagulants was also prominent. When combined the iron trichloride （5 mg/L） with the polymer aluminum sulfate （3 mg/L） , the effect of arsenic removal was the best. The optimal conditions for the compound coagulants show that when pH is 6.00 -7.00 and turbidity is more than 30 NTU or less than 10 NTU, the efficiency of compound coagulants for removal of the arsenic is the highest, which is stable to meet the request of the national hygienic standards for drinking water（ 10 μg/L）.