To remove higher proportions of natural organic matter (NOM) in water treatment plants, over dosing of Al-based coagulant is frequently applied. However, this leads to the risk of an excess of coagulant residue in the clean water. In this study, sequential coagulation with polyaluminum chloride (PACl) and FeCl₃ was proposed to improve the removal of NOM as well as to minimize residual Al. Single dosing with either PACl or FeCl₃ in particular was compared with sequential coagulation, with different dosing sequences of PACl–FeCl₃ (P–F) or FeCl₃–PACl (F–P). At optimum dosage, sequential coagulation P–F showed twice as much dissolved organic carbon (DOC) removal from water containing algogenic organic matter, compared to single dosing of PACl and sequential coagulation F–P. However, sequential coagulation F–P was the most effective approach for humic substance removal that improved DOC removal up to >70% compared to other dosing approaches (<60%). Practical treatment with real water also showed the advantages of sequential coagulation with P–F in improving the removal of low SUVA NOM by 18% compared to the traditional single dosing of PACl. As expected, the Al residues found in both sequential coagulation (0.07 mg/L) were significantly reduced compared to single dosing with PACl (0.15 mg/L), indicating the promising application of sequential coagulation for future safe water treatment.

为了去除水处理厂中更高比例的天然有机物（NOM），经常使用过量的Al基混凝剂。然而，这导致在清洁水中过量的凝结剂残留物的风险。在这项研究中，提出了采用聚氯化铝（PACl）和FeCl ₃进行顺序凝结的方法，以提高NOM的去除率并将残留的Al降至最低。尤其是将PACl或FeCl _3的单次给药与连续混凝进行了比较，采用了不同的PACl–FeCl ₃（PF ）或FeCl ₃给药顺序–PACl（FP）。在最佳剂量下，顺序凝结法PF从含有生藻有机质的水中去除的溶解有机碳（DOC）是单剂量的PACl和连续凝结法PF的两倍。但是，顺序凝血F–P是去除腐殖质最有效的方法，与其他给药方法（<60％）相比，DOC去除率提高了70％以上。与传统的单剂量PACl相比，用实际水进行的实际处理还显示了用P-F顺序凝结的优势，可将低SUVA NOM的去除率提高18％。正如预期的那样，与单次添加PAC1（0.15 mg / L）相比，两次连续凝结（0.07 mg / L）中发现的Al残留量均显着降低，