高碱度水库水混凝过程中残留铝控制

针对高碱度水库水源的某水厂残留铝超标问题,选取碱化度(B)与Alb含量不同的3种铝盐絮凝剂,研究不同投量与pH值下混凝效果与残留铝浓度水平。结果表明,碱化度和Alb含量显著影响混凝效果。DOC和浊度的去除率随着3种絮凝剂AlCl3(B=0)、PACl-1(B=1.2)、PACl-2(B=2.2)投量增大而升高。3种絮凝剂投量在1.5～2.0 mg/L(以铝计)范围内,总铝和溶解铝含量最低。对于该水厂自制的絮凝剂PACl-2,可通过降低絮凝剂碱化度,或将水的pH值降低至7～7.5之间,以此可以提高PACl-2混凝效果,而且可以降低出厂水残留铝浓度。考虑工程应用可行性,可优先考虑调整絮凝剂生产工艺。

Control of residual aluminum during coagulation in treatment of reservoir source water with high alkalinity

To minimize the residual aluminum (Al) levels in the effluent of a drinking water treatment plant (DWTP) with reservoirs source water of high alkalinity,the coagulation performances and the residual Al concentrations using three flocculants,with different basicity (B) and Al_b content,were investigated under varibale Al doses and pH. The results indicate that the basicity and Al_b content significantly affect coagulation behaviors.The removal efficiency of DOC and turbidity increases with elevated doses of AlCl₃ (B=0), PACl-1 (B = 1.2), and PACl-2 (B = 2.2). The concentrations of total Al and dissolved Al are the lowest at Al doses of 1.5~2.0 mg/L for three flocculants.As for the PACl-2, which is prepared by this DWTP, both strategies of decreasing the basicity of flocculant and adjusting the solution pH to 7~7.5 are useful to enhance the coagulation performances and to decrease the residual Al levels. Moreover, the adjustment of flocculant preparation is preferred in the future application.