Anionic Polyelectrolyte
Polyacrylamide · 0.5–3 mg/L
High-molecular-weight (12–22M Da) anionic polyacrylamide flocculant. Bridging-flocculates inorganic and mineral suspended solids into heavy, fast-settling flocs — dosed downstream of coagulants in secondary clarifiers and settling tanks. Performs best at neutral-to-high pH.
Specifications
| Chemical Formula | Polyacrylamide derivative (APAM) |
|---|---|
| Primary Function | Flocculant — forms heavy settled flocs |
| Physical Form | White granular powder |
| Application Point | Secondary clarifier / settling tanks |
| Typical Dosage | 0.5–3 mg/L |
| Best pH Range | 6–10+ |
| Packaging | 25 kg paper/plastic bags |
Where it's used
- Secondary Clarifiers
- Settling Tanks
- ETP & STP
- Mineral / Inorganic Solids
- High-Turbidity Wastewater
Related solutions
What it is and when to use it
Anionic polyelectrolyte is a high-molecular-weight (12–22 million Da) anionic polyacrylamide flocculant. It links small coagulated particles into large, heavy flocs that settle quickly. Use it after a coagulant such as PAC or ferric chloride in clarifiers and settling tanks, especially for inorganic and mineral solids.
Flocculation follows coagulation. After a coagulant neutralises particle charge, long anionic polymer chains adsorb onto several particles at once and bridge them together. The result is a bigger, stronger floc that settles quickly and leaves clearer water. Anionic polymers work best on inorganic and mineral solids at neutral to high pH, typically 6–10+.
It is supplied as a white granular powder in 25 kg bags. Dissolve it slowly into water with gentle mixing to form a dilute solution, allowing it to hydrate fully before dosing. Too much shear breaks the chains, and overdosing can restabilise particles. The typical dosage is 0.5–3 mg/L; confirm the product grade and dose by jar test.
Use it for
- Secondary clarifiers and settling tanks after coagulation
- Effluent with mineral or inorganic suspended solids
- High-turbidity wastewater that needs faster settling
- ETP and STP clarification at neutral to alkaline pH
How to choose
- Jar-test several grades to compare floc size, settling speed and clarity
- Choose anionic for mineral solids; choose cationic for organic or biological sludge
- Use a proper polymer make-up system with gentle mixing and adequate hydration time
- Dose into a gently mixed zone after the coagulant, not into the flash mixer
- Avoid overdosing, which can worsen settling and carry polymer downstream
Frequently asked questions
What is the difference between anionic and cationic polyelectrolyte?
Anionic polyelectrolyte carries a negative charge and is mainly used as a flocculant for inorganic and mineral solids in clarifiers, after a coagulant. Cationic polyelectrolyte carries a positive charge and is mainly used to condition negatively charged organic and biological sludge before dewatering. The right choice depends on the solids, and a jar test confirms it.
How do I prepare an anionic polyelectrolyte solution?
Add the powder slowly into the vortex of stirred water so each granule wets separately, preventing lumps (fish-eyes). Mix gently and allow time for full hydration before dosing. Too much shear breaks the long polymer chains and weakens performance. Follow the supplier guidance on concentration and preparation time.
Why is polyelectrolyte dosed after the coagulant?
The coagulant neutralises the charge on fine particles so they can come together. The polyelectrolyte then bridges those small flocs into larger ones. If the order is reversed, or both are added at the same point, the flocs are weaker and settling is poorer. Dose the polymer into a gently mixed flocculation zone downstream of the flash mixer.
Technically reviewed by Prashant Dwivedi, Co-Founder & Director ·