硫酸铝/PDM复合混凝剂对夏季太湖水的混凝脱浊

Turbidity removal of summer Taihu Lake raw water using composite coagulants of aluminum sulfate and polydimethyldiallylammonium chloride

采用混凝烧杯实验，考察了硫酸铝（AS）／聚二甲基二烯丙基氯化铵（PDM）复合混凝剂的复合比例、PDM特征黏度对夏季太湖含藻水脱浊效果及絮团沉淀性能的影响，并与预加氯工艺条件下的混凝脱浊效果进行了比较．结果表明，对浊度22-26NTU、温度28～30℃、藻含量2．5×10^7个几的太湖水，在与某市水厂混凝强度相近的搅拌强度下，PDM明显提高了AS的混凝脱浊效果与沉淀性能，且AS（以A12O3计）／PDM复合配比越低，PDM特征黏度越高，脱浊效果与沉淀性能越好．在达到2NTU沉淀出水剩余浊度的情况下，AS需4．27mg／L的投加量，而质量复合比例为20：1—5：1的AS／PDM的复合混凝剂需AS投加量3．99-2．07mg／L，减少6．56％～51．52％的AS投加量；在沉淀出水浊度要求提高至1NTU的情况下，AS需7．1lmg／L的投加量，而质量复合比例为20：1～5：1的AS／PDM复合混凝剂需6．61～3．38mg／L的投加量，减少AS投加量13．36％-52．46％．复合混凝剂能够在一定程度上取代预加氯的助凝脱浊功能，尽可能地减少预加氯投加量．

Adopting Jar tests, the influence of composite proportion of aluminum sulfate （AS）/polydimethyldiallyl ammonium chloride （PDM） composite coagulant, and PDM intrinsic viscosity on turbidity removal effect and precipitating performance for summer Taihu Lake high algae contain water were studied, and the turbidity removal effect under the condition of pre-chlorination technique was compared. For the Taihu water of turbidity of 22-26 NTU, temperature of 28-30℃. algae content of 2.5× 10^7/L. PDM enhanced markedly the coagulated turbidity removal effect and the, precipitating performance of AS. and AS （calculated using AI2O3）/PDM composite proportion much lower, and PDM intrinsic viscosity much higher, the turbidity removal effect and the precipitating performance much better. Under the condition of reaching 2NTU precipitating outflow residual turbidity, AS needed dosage of 4.27 mg/L, while composite proportion was 20：1-5：1 AS/PDM composite coagulant needed dosage of 3.99-2.07mg/L, decreasing 6.56%-51.52% AS dosage. Under the condition of reaching 1NTU precipitating outflow residual turbidity, AS needed dosage of 7.11 mg/L, while composite proportion was 20：1-5：1 AS/PDM composite coagulant needed dosage of 6.61-3.38mg/L, decreasing 13.36%-52.46% AS dosage. Composite coagulant could partly replaced the pre-chlorination coagulation-aid function, decreased the dosage of advance chlorine.