优化混凝处理低温低浊黄河水及对余铝的控制

考察了4种混凝剂，高效聚合氯化铝（HPAC），聚合氯化铝（PACl），硫酸铝（Al2（SO4）3），混合PACl和氯化铁（FeCl3），对低温低浊黄河原水的混凝效果与沉后水残留铝含量的关系。结果表明，当采用Al2（SO4）3或PACl做混凝剂时，在取得较好浊度去除的投药量下，水中余铝浓度会超过国家标准（0．2131g／L）。而采用HPAC或FeCl3和PACl复配药剂，在取得与Al2（SO4）3或PACl类似的浊度去除效果的同时，也能较好地控制水中的余铝含量。当HPAC投加量为21mg／L时，沉后水浊度降至1．3NTU，残留铝含量为0．147mg／L。复配投加PACl 15mg／L和FeCl3 12mg／L后，沉后水浊度为1．18NTU，残留铝含量为0．074mg／L。PACl和氯化铁的复配比例需要精确的调控，否则容易导致出水余铁余铝含量增加。而HPAC投加量小于21mtg／L时出水余铝浓度均低于国家标准。因此，在这4种混凝剂中，就混凝效果及余铝控制而言，HPAC更适合充当低温低浊水源水的混凝处理药剂。

Optimization of coagulation performance and residual aluminum control for Yellow River water with low temperature and low turbidity

The performance of four types of coagulants, high performance polyaluminum chloride （HPAC）, polyaluminum chloride （PACl）, Al2 （SO4）3, and a mixture of PAC and FeCl2, was tested with low temperature and low turbidity raw water from Yellow River for their relative coagulative effectiveness and residual aluminum in finished water. The results indicate that when the optimal dosage for turbidity removal by using Al2 （SO4）3 or PACl, the residual aluminum concentration would exceed the national standard （0.2 mg/L）. Both HPAC and composite coagulants of FeCl3 and PACl could reduce the residual aluminum concentration while being able to ob- tain a similar turbidity removal efficiency of Al2 （SO4） 3 or PACl. When dosage of HPAC was 21mg/L, a turbidity of 1.3 NTU and a residual aluminum concentration of 0. 147 mg/L in the coagulated water after sedimentation could be obtained. Similarly, when the composite coagulant of PACl （12 mg/L） and FeCl3 （15 mg/L） were used, a turbidity of 1.18 NTU and a residual aluminum concentration of 0. 074mg/L could be obtained. The ratio of PACl to FeCl3 should be optimized when the composite coagulant was employed, otherwise both the residual alumi- num and ferric iron in settled water would increase. For HPAC, when the dose of addition was less than 21 mg/L, the residual aluminum concentration would be below the limits of national drinking water standards. Therefore, a- mong the four types of coagulants, HPAC was a better coagulant for treating the source water with low temperature and turbidity in terms of both coagulative effects and residual aluminum control in treated water.