Cationic Polyelectrolyte
Polyacrylamide · 1–5 mg/L
Cationic polyacrylamide (10–80% charge density) that neutralises negatively-charged organic and biological sludge — the standard conditioner for decanter centrifuges, belt presses, filter presses and screw presses. Increases cake dryness, improves filtrate clarity, and cuts polymer consumption per kg of dry solids.
Specifications
| Chemical Formula | Polyacrylamide derivative (CPAM) |
|---|---|
| Primary Function | Sludge dewatering conditioner |
| Physical Form | White granular powder / liquid emulsion |
| Application Point | Decanter / filter press / screw press |
| Typical Dosage | 1–5 mg/L |
| Solution Make-up | 0.1–0.5% stock solution |
| Packaging | 25 kg bags / drums |
Where it's used
- Sludge Dewatering
- Decanter Centrifuges
- Belt & Filter Presses
- Screw Presses
- Organic / Biological Sludge
Related solutions
What it is and when to use it
Cationic polyelectrolyte is a positively charged polyacrylamide, available with 10–80% charge density, used mainly to condition organic and biological sludge before dewatering. Use it ahead of decanter centrifuges, belt presses, filter presses and screw presses to improve cake dryness and filtrate clarity.
Biological and organic sludge particles carry a negative surface charge and hold water tightly. Cationic polymer neutralises that charge and bridges the particles into robust flocs that release water under mechanical pressure. The result is a drier cake, cleaner filtrate or centrate, and lower polymer consumption per kilogram of dry solids.
Grades vary by charge density and molecular weight, and the best choice depends on the sludge type, solids concentration and dewatering machine, so it is selected by lab screening and plant trial. It is supplied as white granular powder or liquid emulsion in 25 kg bags or drums, and is usually made up as a 0.1–0.5% stock solution. The typical dosage is 1–5 mg/L, but confirm it by trial.
Use it for
- Sludge dewatering with decanters, belt presses, filter presses or screw presses
- Biological sludge from STPs and activated-sludge ETPs
- Organic sludge from food, dairy, paper and similar industries
- Sludge thickening ahead of dewatering
How to choose
- Screen several charge densities on your sludge in the lab, then confirm on the machine
- Choose powder or emulsion based on your make-up system and handling preferences
- Prepare a 0.1–0.5% stock solution and allow full hydration
- Optimise the dose point and mixing energy for the specific dewatering machine
- Track cake dryness, filtrate clarity and polymer use per kg of dry solids
Frequently asked questions
Why is cationic polyelectrolyte used for sludge dewatering?
Organic and biological sludge particles are negatively charged and bind water tightly. Cationic polymer neutralises the charge and bridges particles into strong flocs that release water in a centrifuge or press. This gives a drier cake, clearer filtrate and lower disposal cost. The dose is optimised by trial on the actual machine.
What charge density of cationic polymer should I choose?
Cationic polyacrylamides are available from 10% to 80% charge density. The right choice depends on sludge type, age and solids concentration, as well as the dewatering machine. Lab screening of several grades on a fresh sludge sample, followed by a plant trial, is the reliable way to choose. NWPL can support the screening.
What concentration should the polymer stock solution be?
Cationic polyelectrolyte is usually made up as a 0.1–0.5% stock solution. Solutions that are too concentrated are viscous and mix poorly with sludge, while very dilute solutions need larger volumes. Allow the polymer to hydrate fully before use, and dilute it further inline if your machine supplier recommends it.
Technically reviewed by Prashant Dwivedi, Co-Founder & Director ·