• 17/19 Gò Dầu, Phường Tân Quý, Quận Tân Phú, Tp. HCM

1. What is Poly Aluminium Chloride (PAC)?

2. The PAC application in water treatment

3. PAC filling system




1. What is Poly Aluminium Chloride (PAC)?

Poly aluminium chloride (PAC) is the chemical that used for water treatment, also known as a sedimentation, the general molecular formula [Al2(OH)nCl6-n]m. The aluminum content in PAC accounts for 28 – 32%, which helps to effectively coagulate the dirt in the water without causing harm to the environment.

This chemical is capable of settling flocculation compounds with suspended substances such as organic matter (soluble or insoluble), viruses, bacteria, heavy metals present in water, separate and remove these substances from the water easily.

PAC can be in liquid or powder form. In liquid form PAC is yellow-brown, while powdered PAC is yellow or white as shown below. Powdered PAC can be completely dissolved in water and can be stored under normal conditions for a long time, so it is preferred for use.


Common PAC forms and colors


Basic properties of Poly aluminium chloride (PAC):

  • Exist in liquid or powder form
  • Color: yellow brown, lemon yellow, ivory white
  • Completely soluble in water at any ratio, with exothermic
  • Strong absorbency
  • Best operations in pH 6.5 – 8.5
  • Can be preserved and stored for a long time at room temperature


2. The PAC application in water treatment


Water treatment chemicals – PAC (sedimentation aids) are widely used in the water treatment industry thanks to outstanding features such as fast flocculation time, large floc, easy settling, low dosage and can be dissolved in water in any proportion.

Besides, another outstanding advantage of PAC is the settling efficiency 4-5 times higher than other water treatment chemicals such as alum aluminum sulfate, NaOH, Hydrogen Peroxide, etc… Therefore PAC is very popularly used by water supply companies and water plants in the technological processes of domestic, supply water or wastewater treatment.



Depending on the sediment content and different properties of the water to be treated, the dose of PAC we need to use is different. However, PAC has been very effective, just using a low dose can clean a large volume of wastewater.

Thanks to the above characteristics, PAC is applied in most of the following technological processes:

  • Treatment of domestic water
  • Industrial wastewater treatment
  • Water treatment
  • Aquaculture water treatment
  • The colloid for paper industry
  • Treatment of wastewater containing suspended residues in ceramics, bricks, paper, dyeing…


3. PAC filling system


The process of treating and cleaning water with PAC


PAC action mechanism:

PAC powder after being diluted to form a solution, it will be put into the tank and mixed with raw water. PAC has the general molecular formula [Al2(OH)nCl6-n]m, when dissolved in water, dissociation and hydrolysis reactions occur, creating particles in water as follows: Al3+, Al(OH)2+, molecule Al(OH), Al(OH)4, three polymer particles: Al2 (OH)24+, Al3(OH)45+, Al13O4(OH)247+ and solid Al(OH)3.

In which, Al13O4(OH)247+  is Al13 that is the main and best flocculating agent. Because the size of the polymer particles is much larger than Al3+, the floc is formed larger and stronger, which is favorable for the next settling process.


PAC filling system in water treatment plant



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