USER GUIDE WHEN USING PAC

1. Introduction to PAC

- PAC (Poly Aluminum Chloride) is a type of aluminum alum that exists in the form of polymers. Molecular formula [Al₂(OH)_nCl_6-n]_m. Currently, PAC is produced in large quantities and widely used in advanced countries to replace alum aluminum sulfate in domestic water treatment.

- PAC has many advantages compared with aluminum sulfate alum for the deposition process. Such as the internal sedimentation efficiency is higher than 4-5 times, the flocculation time is fast, less changes in the pH of the water, no or very little support, no need for complicated equipment and manipulations, cloudy when using lack or excess of alum. PAC is better able to remove dissolved and insoluble organic matter and heavy metals better than sulfate alum. This is particularly significant in creating high quality water sources, including treating turbid water during the flood season into domestic water. Therefore, developed countries use PACs in domestic water supply plants.

- There are solid PACs and liquid PACs. Solid is an ivory-white powder that dissolves completely in water. Users just need to mix PAC powder into a 5% or 10% solution with clear water, add the solution corresponding to the flocculation to the water to be treated, stir well and allow to settle in. Under normal storage conditions (sealed, kept in a dry place, at room temperature) can store for a long time. PAC liquid is yellow brown in color and can be stored in plastic bottles or cans for long term storage.

- The dosage of PAC used for 1m3 of surface water is 6g to 10g PAC for 15NTU - 90NTU turbid water and 10 - 30g for high turbidity> 90NTU. The exact dosage used is determined by direct testing of the treated water.

- PAC can be used to treat wastewater containing suspended residues such as industrial wastewater from ceramics, bricks, paper, dyeing, seafood processing factories, cattle slaughter factories, PACs to treat 1 m3 of wastewater. in the range of 15-30 grams, depending on the content of suspended sediment and the nature of each type of wastewater. The exact dosage should be determined through direct test with the object to be handled.

2. Advantages of PAC

- High PH stability, Easy to adjust pH when handling so it can save chemicals used to increase alkalinity and accompanying equipment such as metering pumps and chemical tanks compared to using aluminum alum.

- Reducing the volume of sludge during treatment.

- Increases water clarity, prolongs the filtration cycle, increases water quality after filtration.

- The dosage is low, the cotton is large and easy to settle.

- Less corrosive equipment.

PAC works best at around PH = 5-8.5. Therefore, in this PH, the heavy metal ions are precipitated and sink to the bottom or stick to the colloidal particles to form.

 3. Disadvantages

Because it has a very strong effect at low doses, over-PACing will melt the colloidal particles.

 4. User guide when using PAC

Blended into a 5% -10% solution and added to the source water to be treated.

- Dosage of surface water treatment: 10-25g / m3 PAC depending on the turbidity of raw water.

- The dose of wastewater treatment (paper factories, weaving, dyeing, ...) from 20-200g PAC / m3 depending on the content of suspended substances and the nature of the wastewater.

- Standard PAC content is determined practically for each type of water to be treated.

 5. Chemical composition PAC

   
Note: The quality of PAC and heavy metals have been analyzed and verified at the Center for Environmental Engineering and Chemical Safety, branch of the Institute of Industrial Chemistry of Vietnam.