硫化物沉淀法在水源突发锌污染中的应用研究

Application of Sulfide Precipitation to Sudden Water Zinc Pollution

水源遭受锌污染时,水厂常规处理工艺对溶解性的锌几乎无去除作用。硫化锌是难溶沉淀物,因此硫化物沉淀法可用作自来水厂应急除锌净水工艺。试验结果表明:采用硫化物沉淀法应急除锌时,硫化物可与混凝剂在同一位点经不同投加系统投加,无需预处理时间;硫化物投加量应根据原水锌浓度调整,当投加质量比(硫化物浓度与锌离子浓度之比)在理论比值时效果最好,可以应对原水锌浓度数十倍超标,且出水硫化物浓度能保持在标准范围内。当因原水锌浓度波动而造成投加的硫化物过量时,水厂后续消毒过程可将过量硫化物氧化成硫代硫酸盐和亚硫酸盐,不会对出水水质产生影响。

Dissolved Zn^2＋ cannot be removed by conventional water treatment processes when source water is polluted with zinc. Sulfide precipitation can be used as an emergency water purification technology because zinc sulfide is an insoluble precipitate. The experimental results showed that the sul- fide could be dosed with the coagulant at a same point by different dosing systems without pretreatment time. The concentration of the sulfide should be adjusted according to the concentration of zinc in raw water. Good treatment effect was achieved when the mass concentration ratio between the sulfate and the zinc was near the theoretical ratio. The sulfide precipitation technology could cope with the concentration of zinc, which was several dozen times higher than that of drinking water standards. The concentration of sulfate in the treated effluent would meet the standards. The excessive sulfide caused by zinc variation could be oxidized to thiosulfate and sulfite during the disinfection, which would not impact the water quality.