PAC & ACH
PT Beta Pramaesti Asia
1. PAC (Polyaluminum Chloride)
Full name: Polyaluminum Chloride
General chemical formula: Alₙ(OH)ₘCl₍₃ₙ₋ₘ₎
Function and use:
PAC is a coagulant used to purify water by binding fine colloidal particles to form flocs that are easily deposited.
PAC is used in:
- 
Drinking water treatment 
- 
Industrial wastewater treatment 
- 
Paper industry (for fiber separation) 
- 
Textile industry (process water purification) 
Advantages of PAC:
- 
Effective over a wider pH range (pH 5-9) 
- 
Lower usage dose compared to alum 
- 
Produces less sludge 
- 
Does not lower the pH of the water too much 
Disadvantages:
- 
Relatively higher price than alum 
- 
Can leave aluminum residue if the dose is excessive 
2. ACH (Aluminum Chlorohydrate)
Full name: Aluminum Chlorohydrate
General chemical formula: Al₂(OH)₅Cl
Function and use:
ACH is also an aluminum-based coagulant, with a higher active aluminum content than PAC.
ACH is widely used for:
- 
Premium drinking water treatment (e.g. bottled water) 
- 
Industrial applications with high hygiene standards (food, pharmaceutical) 
- 
Cosmetics (especially antiperspirants/deodorants) 
Advantages of ACH:
- 
Has high basicity (70-83%), meaning it is more stable and efficient 
- 
Produces faster and larger flocs 
- 
Reduces dissolved organic content (DOC/TOC) better 
- 
More dose-efficient than PAC 
Disadvantages:
- 
More expensive than PAC 
- 
Sensitive to pH extremes (less effective at pH < 5) 
Brief Comparison of PAC vs ACH
| Aspect | PAC | ACH | 
|---|---|---|
| General form | Liquid or solid | Liquid | 
| Basicity (OH- content) | 50-70% | 70-83% | 
| Coagulation efficiency | Good | Very good | 
| Required dosage | Medium | Low | 
| Stability | Good | Very good | 
| General application | Drinking water, waste water | Premium drinking water, cosmetics | 
Conclusion
- 
PAC is suitable for general use in water treatment plants as it is economical and effective. 
- 
ACH is used for premium grade applications or high hygienic standards, where clarity and aluminum residues are strictly controlled. 
