微污染原水中各类有机物在铁盐混凝过程中的去除效果

Study on removal effect of different organic fractions from light-polluted raw water by coagulation

通过XAD-8/XAD-4吸附树脂联用技术将黄浦江微污染原水中溶解性有机物分为疏水酸、非酸疏水物质、弱疏水物质及亲水物质4类有机物,研究了铁盐混凝工艺对黄浦江水中这4类有机物的去除效果。三氯化铁在最佳混凝条件下,即投加量为8 mg/L(以Fe计)和pH=5时,水中的溶解性有机碳(DOC)和UV254去除率分别达到39%和51%。有机物的亲疏水性对混凝工艺有较大影响,混凝法倾向于优先去除水中疏水性有机物,而疏水性有机物的酸碱性对混凝工艺而言,没有明显影响,酸性和非酸疏水物质均能被混凝工艺有效去除。疏水酸是水中最主要的三氯甲烷类消毒副产物的前体物质,混凝工艺对于三氯甲烷类消毒副产物有良好的控制作用,总体减少了52%的生成量。而不同类的有机物之间,混凝工艺对消毒副产物控制效果不同,其中对疏水酸的三氯甲烷消毒副产物的控制效果最好,减少了71%的生成量,对亲水物质的控制效果最差,三氯甲烷生成量仅减少了12%。黄浦江原水中疏水酸表现出比亲水物质更强的生物毒性,混凝工艺能明显地降低原水的毒性。

Removal effects of four different DOM fractions,hydrophobic acids,non-acid hydrophobics,tasnsphilics and hydrophilics separated by XAD-8 and XAD-4 resins,in a ligh-polluted raw water from Huangpu River through coagulation process were studied.The best coagulation condition by the coagulant of ferric chloride occurred at the dosage of 8 mg/L,and pH=5,while the removal rate of the DOC and UV254 reached 39% and 51% respectively.It was indicated that the hydrophobicity of organic fractions had noticeable effect on coagulation process,with highest removal efficiency of hydrophobic acids,then followed by non-acid hydrophobics and tasnsphilics,and the least of hydrophilics.However,coagulation didn’t exhibit obvious preference between acidic and basic hydrophobic organic fractions.Although the coagulation process could effectively control the production of trihalomethanes by about 52%,the potential removal rates of trihalomethanes by coagulation from different organic fractions varied very much,with the highest from hydrophobic acids,the most reactive precursors,by 71%,and the least from hydrophilics by only 12%.The hydrophibics from the Huangpu River water showed higher toxicity than the hydrophilics.After coagulation process,the toxicity of the raw water was obviously reduced.