Application Research of Polyaluminium chloride

PAC coagulation is also crucial for treating water sources rich in algae in drinking water treatment plants. The removal efficiency of high-activity and low-activity microcystis was compared through the PAC coagulation experiment, and the effects of cell characteristics and extracellular organic matter (dEOM) on its removal rate were discussed. After coagulation sedimentation, the removal rate of low-activity cells (38.3% - 99.3%) was higher than that of high-activity cells (14.5% - 85.9%). This is because the buoyancy of low-activity cells decreased, and due to the presence of functional bonds such as aromatic groups, O-H, N-H, and C-N on their hydrophilic cell surfaces, The adsorption interaction with Al (OH) 3 is enhanced. Compared with in situ dEOM, after treating the two samples with PAC of the same initial concentration, the removal rate of low-activity cells (1.3% - 90.5%) was significantly lower than that of high-activity cells (2.2% - 98.2%). This is because the content of low relative molecular weight peptides <10 kDa in dEOM increased through complexation

The supply of negative charges hinders the coagulation removal of low-activity cells. Studies have shown that a decline in cell viability can strongly affect the coagulation efficiency of water sources rich in algae.

PAC, as a water treatment agent, has been widely used worldwide due to its high charge neutralization capacity. Studies show that the characteristics of raw water are important factors determining the application effect of PAC, but few studies focus on the influence of other factors of water quality on the performance of PAC. We used two typical PACs with different alkalinity to study the reasons why their performance depends on the characteristics of the raw water. Use polymer colloidal substances with high content (Alb+Alc)

The high alkalinity PAC (HB-PAC) will lead to the formation of very slow flocs in the raw water with a low concentration of sulfate ions, and the turbidity removal rate is relatively low. Although HB[1]PAC has a higher charge neutralization capacity, its performance is inferior to that of normal alkalinity PAC (NB-PAC). However, bicarbonate ions contribute very little to the hydrolyzation-precipitation process of high-alkalinity PAC, which means that the types of anions in the raw water will affect the hydrolyzation-precipitation process and flocculation capacity of PAC.