The Studies On Kaolin Suspension Coagulation Of PACI

Polyaluminum chloride (PACl) is widely used in water coagulation process. Butthere were diverse reports on its effectiveness under different water conditions. Basedon measuremets of characteristics of PACl hydrolysis flocculation system, the effects ofZeta potential, particle size distribution and turbidity removal efficiency versus varingfactors, such as different kaolin particle sizes and different water conditions, werestudied using laboratory-made PACl coagulation kaolin suspension.The main conclusions are summarized below:(A) under the best PACl dosagecoagulation of small particle size kaolin in pure water is less effective. The turbidityremoval of coagulation with PACl in B=2.5at pH=9reached14.89%; The turbidityremoval of coagulation with PACl in tap water at pH=9was enhanced up to45.3%.Addition of NaCl and CaSO4in certain amount can improve the turbidity removal ofcoagulation in pure water.(B) Compared with kaolin suspension with489nm in size,the turbidity removal of kaolin suspension with2.7μm size is not much different in thesame PACl dosage; But when the dosage of PACl increased into0.4mM, the turbidityremoval of coagulation can achieve greater value with91.79%at pH=9; Addition of HAreduced slightly turbidity removal at pH=8, and the more the HA’s content the lessturbidity removal. The addition of sulfate with10mg/L can increase the turbidityremoval of coagulation by PACl in0.2mM dosage at pH=9, at PACl dosage of0.4mM, the turbidity removal reached93.7%; Inintial turbidity of kaolin suspension hadnot signicficant effects on turbidity removal in PACl coagulation.(C) The turbidityremoval of coagulation with industrial PACl is not as good as that with laboratory-madePACl.