Poly Aluminium Chloride (PAC)
(Aln(OH)mCln-m)x · 20–80 mg/L
Pre-hydrolyzed inorganic coagulant for charge neutralisation — reacts faster than alum, performs across a wide pH 5–9 window, and needs far less pH correction. Produces 30–50% less chemical sludge and lower residual aluminium, with dense rapid-settling flocs for high-turbidity ETP and WTP streams.
Specifications
| Chemical Formula | (Aln(OH)mCln-m)x |
|---|---|
| Primary Function | Inorganic coagulant for charge neutralisation |
| Physical Form | Powder / Liquid (both available) |
| Application Point | Flash mixer / primary clarifier |
| Typical Dosage | 20–80 mg/L |
| Working pH Range | 5–9 |
| Packaging | 25 kg bags / 50 kg drums |
Where it's used
- ETP Primary Treatment
- STP Clarification
- Water Treatment Plants
- High-Turbidity Streams
- Colour & TSS Removal
Related solutions
What it is and when to use it
Poly aluminium chloride (PAC) is a pre-hydrolysed inorganic coagulant that neutralises the charge on suspended and colloidal particles so they clump together. Use it as the first chemical stage in ETPs, STPs and water treatment plants to remove turbidity, colour and TSS across a wide working pH of 5–9.
Coagulation is the first step in chemical clarification. PAC destabilises fine particles in the flash mixer, then an anionic polyelectrolyte bridges the small flocs into larger ones that settle in the clarifier. PAC is already partly hydrolysed, so it works faster than alum and consumes less alkalinity, reducing the need for pH correction.
Compared with alum, PAC typically produces less chemical sludge and lower residual aluminium. It is supplied as powder or liquid in 25 kg bags or 50 kg drums. The typical dosage is 20–80 mg/L, but the right dose depends on your water, so always confirm it with a jar test on a representative sample.
Use it for
- Primary treatment in industrial ETPs to remove TSS and colour
- Clarification in STPs and tertiary treatment
- Drinking water treatment plants with variable turbidity
- Streams where alum would need extensive pH correction
How to choose
- Run jar tests to find the dose and confirm floc formation and clarity
- Choose powder (easier storage) or liquid (easier dosing) based on your dosing system
- Check that the working pH falls within 5–9 or plan pH correction
- Pair with an anionic polyelectrolyte if faster settling is needed
- Review sludge handling, as reduced sludge is one of the main advantages over alum
Frequently asked questions
How is PAC different from alum?
PAC is pre-hydrolysed, so it forms flocs faster, works across a wider pH range (5–9) and consumes less alkalinity than alum. That means less pH correction, less chemical sludge and lower residual aluminium in treated water. Compare total treatment cost, including sludge disposal, when choosing between them.
What dose of PAC do I need?
The typical range is 20–80 mg/L, but the correct dose depends on turbidity, colour, pH and the type of solids in your water. Run a jar test on a representative sample, comparing several doses for floc size, settling speed and clarity, then fine-tune the dose on the plant. NWPL can help with jar testing.
Should PAC be used with a polyelectrolyte?
Often, yes. PAC neutralises particle charge and forms small flocs; an anionic polyelectrolyte dosed afterwards bridges those flocs into larger, heavier ones that settle faster. Dose PAC in the flash mixer and the polyelectrolyte in the flocculation zone, and confirm the combination in a jar test.
Technically reviewed by Prashant Dwivedi, Co-Founder & Director ·