Is polyaluminium chloride a safe coagulant?

Polyaluminium Chloride is a safer alternative to several other chemical coagulants. For instance, aluminium sulphate has been widely used as coagulant for many years. It removes contaminates and general turbidity from water during the water treatment process.

How does polyaluminium chloride coagulation work?

Continuous coagulation with polyaluminium chloride has long been recommended by PWTAG – especially in the light of the threat from Crytposporidium. Like all coagulants PAC works by extracting and then clumping together dissolved, colloidal and suspended matter. The resulting floc is then trapped on the filter.

Is polyaluminium chloride better than polyelectrolyte – alum-based coagulation?

At the Barekese Water Treatment Plant in Ghana, an alternative, the polyelectrolyte – polyaluminium chloride (PAC) is also used in coagulation but limited information is available on the operating conditions required to achieve better performance than alum-based coagulation.

Why is polyaluminium chloride important during water treatment process?

Polyaluminium chloride has several features important during water treatment process, and the features are outlined in the following list:- PAC helps speeding up the process of flocs formation, and the settling of the flocs at the bottom. The process makes flocs that are formed easier to be filtered out.

What is the coagulation removal rate of polyaluminium chloride (PAC)?

Without coagulation removal rates in a single pass of a medium-rate filter were about 50%. This was dramatically improved, to over 90%, by dosing polyaluminium chloride. PAC is directly and continuously dosed from the containers in which it is delivered at a rate of about 0.1ml/m 3 of the circulation flow.

How should coagulation pH be matched to raw water alkalinity?

PACl basicity should be matched to raw water alkalinity, so that coagulation pH is as close as possible to the pH of minimum solubility of the coagulant. The solids separation process used for treatment was also found to be important for coagulant selection.