复合聚铝处理秋季长江水脱浊研究

通过混凝烧杯实验,探讨了特征黏度系列化的聚二甲基二烯丙基氯化铵(PDM)与液体聚合氯化铝(PAC)复合得到的稳定型复合混凝剂用于对秋季微污染长江水强化混凝处理效果。结果表明,对温度为16～18℃,浊度为70 NTU左右的秋季长江水,沉淀池出水在达到6 NTU的南京某水厂现行浊度标准的情况下,PAC需1.66mg/L的投加量,质量配比分别为20∶1、10∶1、5∶1的PAC(以Al2O3计)/PDM复合混凝剂所需投加量随特征黏度变化为1.38～1.26、1.19～1.14、1.16～1.13 mg/L,相对于PAC可减少投加量16.87%～24.10%、28.31%～31.32%、30.12%～31.93%。复合混凝剂还提高了絮体密实度与沉淀性能。由此可见,PDM明显改善了PAC的混凝脱浊效果,PAC/PDM复合比例越低,PDM特征黏度越高,脱浊效果与沉淀性能越好。考虑未来社会对水质的要求,若使沉淀池出水达到2 NTU左右,则PAC需3.35 mg/L左右的投加量,而复合比例分别为20∶1、10∶1、5∶1的复合混凝剂仍能比单独使用PAC减少19.10%～30.45%的投加量。

Studies on Turbidity Removal of Tiny Polluted Autumn Yangtze River Raw Water Using Composite Coagulants of Polyaluminum Chloride

The enhanced coagulation processes to autumn Yangtze River raw water using steady composite coagulants,prepared by polyaluminum chloride(PAC) and Polydiallyldimethylammonium chloride(PDM) with different intrinsic viscosity,were reported in this paper.Jar tests were used to investigate the influences of the composite ratios of PAC to PDM and the intrinsic viscosity of PDM on the turbidity removal and settlement performance.The results showed that for the Yangtze River raw water with temperature of 16～18 ℃ and the turbidity of 70 NTU,the efficiency of turbidity removal of composite coagulants was remarkable.For the current process of potable water treatment,the residual turbidity of the supernatant from the settlement tank must be below 6 NTU.The dose of PAC and composite coagulants with the mass ratios of 20∶ 1,10∶ 1,5∶ 1 and the PDM intrinsic viscosity of 0.524,1.53,2.47 dL/g were 1.66,1.38～1.26,1.19～1.14,1.16～1.13 mg/L respectively,and the composite coagulants could decrease the PAC dose by 16.87%～24.10%,28.31%～31.32%,30.12%～31.93%.In case that the residual turbidity of 2 NTU will be required in the future,the dosage of 3.35 mg/L is necessary for treatment by PAC,but composite coagulants will decrease the PAC dose by 19.10%～30.45%.In general,PDM can assist PAC to increase the density,improved the turbidity removal efficiency and settlement performance.The lower the mass ratios of PAC to PDM and the higher the intrinsic viscosity of PDM,higher the efficiency will be.