What is Poly Aluminium Chloride?

Poly Aluminium Chloride (PAC) is a water-soluble inorganic polymer coagulant widely used in the treatment of drinking water, wastewater, and industrial effluents. It is produced through the reaction of aluminium hydroxide or aluminium oxide with hydrochloric acid or by the electrolysis of an aluminium chloride solution.

Chemically, it has the general formula [Al2(OH)nCl6-n]m where n varies from 1 to 5, and m refers to its degree of polymerization. The compound exists as a highly charged polynuclear aluminum complex that exhibits excellent flocculation properties due to its high charge density.

In water treatment processes, Poly Aluminium Chloride is mainly applied for:

1.Coagulation: 

PAC neutralizes the negative charges on suspended particles, destabilizing them and causing them to aggregate into larger flocs.

2. Flocculation: 

Once the smaller particles have aggregated, PAC promotes the formation of large, stable flocs which can then be easily removed by sedimentation or filtration.

3. Clarification: 

By removing turbidity, color, and microorganisms, PAC helps clarify water and improve its overall quality.

The effectiveness of Poly Aluminium Chloride depends on factors such as pH, temperature, dosage, and the type of contaminants present in the water. Different grades of PAC are available to suit different applications, varying in their basicity and Al content.