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Polyaluminium Chloride (PAC) is an inorganic polymer coagulant widely used as an efficient alternative to traditional alum.
So, what is PAC, and why is it considered one of the most effective coagulants in water treatment today?
Its high cationic charge enables it to neutralize suspended solids, enhance floc formation, and improve water clarity efficiently.
The manufacturing of PAC involves several key stages:
Raw Materials
The main raw materials include aluminium hydroxide, aluminium oxide, aluminium ash, hydrochloric acid, or hydrogen chloride gas.
Different raw materials and formulations determine the purity, color, and application of PAC.
√ Food-grade PAC: made from high-purity aluminium hydroxide, light yellow or white in color.
√ Industrial-grade PAC: made from bauxite or aluminium ash, darker yellow to brownish tone.
Production Process
Aluminium hydroxide reacts with hydrochloric acid at 90–100°C under controlled pH to form aluminium chloride.
Through polymerization, a polyhydroxy aluminum chloride polymer with high charge density is obtained.
Adjusting basicity (degree of polymerization) controls product performance.
High-basicity PAC (70–90%) shows faster floc formation and fewer impurities.
Types and Purity Levels
√ Spray-dried PAC: high purity, quick dissolving, suitable for potable water.
√ Drum-dried PAC: economical, ideal for industrial wastewater.
√ Liquid PAC: used in continuous dosing systems for municipal and industrial plants.
PAC chemical offers significant benefits:
→ Works effectively over a wide pH range (4–9)
→ Requires lower dosage than alum
→ Produces less sludge, reducing disposal costs
→ Consumes less alkalinity, minimizing pH correction
→ Rapid floc formation and fast settling
PAC is used across diverse industries:
→ Drinking water purification
→ Industrial wastewater treatment
→ Textile, paper, and dyeing wastewater
→ Food and dairy processing
→ Oil & gas, mining, sand washing, and coal washing
| Industry | Recommended Combination | Application Effect |
|---|---|---|
| Drinking Water | PAC + Activated Carbon | Removes color, odor, and organics |
| Textile & Paper | PAC + Anionic PAM | Rapid flocculation and decolorization |
| Coal/Sand Washing | PAC + Cationic PAM | Enhances clarity and sedimentation |
| Food & Dairy | PAC + Caustic Soda + Activated Carbon | Demulsifies oils, removes odor/color |
| Slaughterhouse & Livestock | PAC + Cationic PAM + Fluoride Remover | Removes ammonia nitrogen, SS, odor |
| Electroplating & Heavy Metal | PAC + Polyamine | Eliminates heavy metals and turbidity |
A1: PAC is mildly acidic but works effectively across a pH range of 4–9, reducing the need for pH adjustment compared to alum.
A2: When used at regulated dosages, PAC residual aluminium meets WHO standards, ensuring safe water for human consumption.
A3: PAC is a pre-polymerized coagulant that performs efficiently at lower dosages, has a wider pH range, and produces less sludge.
Alum (aluminium sulfate) is temperature-sensitive and requires higher dosages, making PAC more cost-effective overall.
Click below to learn more about polyaluminium chloride
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