Floc morphology and cyclic shearing recovery: comparison of alum and polyaluminum chloride coagulants.
Floc morphology and cyclic shearing recovery: comparison of alum and polyaluminum chloride coagulants.
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DOI：
10.1016/j.watres.2003.10.005
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发表时间：
2004
期刊：
影响因子：
12.8
通讯作者：
Kevin McCurdy;K. Carlson;D. Gregory
中科院分区：
文献类型：
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作者：
Kevin McCurdy;K. Carlson;D. Gregory
本研究研究了明矾、聚合氯化铝(PACl)以及这些混凝剂的混合絮凝剂的絮凝形成和再聚集潜力。实验室规模试验包括对发育良好的絮凝体、剪切后的絮凝体和不可沉降(滤池进水)絮凝体的絮体形态进行表征。观察了不同混凝剂的应用，以产生形态不同的不稳定絮体。明矾处理的平均絮体大小从混凝状态降低到不稳定状态，而PAC1和PAC1/明矾处理在这些工艺之间产生了相似大小的絮体。Zeta电位分布测量表明，明矾处理导致了从凝结状态到非稳定状态的负移，而PAC1和PAC1/明矾处理没有显着变化。使用光度色散分析仪(PDA)比较了不同混凝剂处理在剪切诱导的团聚体破碎和恢复方面的差异。PDA允许动态监测初始的絮凝体聚集，并测量循环剪切的恢复程度。PACl/明矾处理从剪切中恢复的程度最大，这可能是由于更有效的电荷中和提高了碰撞效率。
This study investigated the floc formation and re-aggregation potential for alum, polyaluminum chloride (PACl) and a blend of these coagulants. Bench-scale testing included floc morphology characterization for well-developed floc, post-shear floc, and non-settleable (filter influent) floc. Different applications of coagulants were observed to produce non-settleable floc that was morphologically different. The alum treatment had a decrease in average floc size from coagulated to non-settleable conditions, whereas the PACl and PACl/alum treatments resulted in similar sized floc between these processes. Zeta potential distribution measurements showed that the alum treatment resulted in a negative shift from coagulated to non-settleable conditions whereas the PACl and PACl/alum treatments had no significant shift. A photometric dispersion analyzer (PDA) was employed to compare the differences between coagulant treatments with respect to shear induced aggregate breakup and recovery. The PDA allowed a dynamic monitoring of initial floc aggregation and measured the degree of recovery from cyclic shearing. The degree of recovery from shearing was greatest for the PACl/alum treatment likely as a result of increased collision efficiency due to more effective charge neutralization.