Polyacrylamide (PAM) is one of the most widely used polymers in water treatment and industrial solid-liquid separation. It works as a flocculant, sludge dewatering polymer, retention aid and thickener.
For most industrial buyers, the question is not whether PAM works—it’s which grade works. A polymer that dewaters municipal sludge beautifully can fail completely on mining tailings. A grade suited to textile effluent may be wrong for paper-mill wastewater.
This guide covers what PAM is, the three charge types, their key specifications (molecular weight, charge density, dosage), typical applications, and a practical method for choosing the right grade—including a comparison table you can use as a quick reference.
What Is Polyacrylamide (PAM)?
Polyacrylamide is a water-soluble polymer built from acrylamide monomer units. Industrially it is supplied as white granules/powder (typical active content ≥ 88–90%) or as emulsion/liquid. Dissolved in water, its long chains bridge fine suspended particles into larger, faster-settling flocs.
That bridging action is why polyacrylamide flocculant improves floc formation, settling rate, filtration and dewatering efficiency. In short: PAM makes fine particles far easier to separate from water.
Handling note: PAM powder should be dissolved at roughly 0.1–0.3% concentration, added slowly into a vortex under moderate stirring, and given 30–60 minutes to fully hydrate. Over-mixing shears the chains; dumping powder too fast creates “fish-eyes.”
The Three Types of PAM Polymer
Different waste streams differ in particle charge, pH and organic load—so PAM is classified by ionic charge.
1. Anionic Polyacrylamide (APAM)
Negatively charged. Best for inorganic suspended solids—mineral fines, sand, clay, weakly charged particles.
- Typical molecular weight: 8–20 million
- Typical anionic (charge) degree: 10–40%
- Applications: mining wastewater, mineral processing, sand-washing and coal-washing water, many industrial effluents
- Goal: better settling, clarification and solid-liquid separation
2. Cationic Polyacrylamide (CPAM)
Positively charged. The go-to for sludge dewatering and organic-rich wastewater, where it neutralizes negatively charged organic particles and builds strong, water-releasing flocs.
- Typical molecular weight: 6–12 million
- Typical cationic (charge) degree: 10–60%
- Applications: municipal & industrial sludge dewatering, food-processing wastewater, paper-mill wastewater, biological sludge
- Goal: lower cake moisture, better dewatering on belt/screw/centrifuge presses
3. Nonionic Polyacrylamide (NPAM)
Little or no ionic charge. Used in specialized systems where charge interaction isn’t the main mechanism or where APAM/CPAM underperform—often at lower pH or with mixed particle loads.
- Typical molecular weight: 5–12 million
- Applications: complex or acidic wastewater, certain conditioning and paper processes
Quick Comparison Table
| Property | Anionic (APAM) | Cationic (CPAM) | Nonionic (NPAM) |
|---|---|---|---|
| Charge | Negative | Positive | Neutral |
| Molecular weight | 8–20 M | 6–12 M | 5–12 M |
| Charge degree | 10–40% | 10–60% | ~0% |
| Best for | Inorganic/mineral solids | Organic sludge dewatering | Complex/low-pH systems |
| Typical dosage | 0.5–3 ppm (clarification) | 3–10 kg/ton dry solids (dewatering) | Application-dependent |
| Key sectors | Mining, mineral, sand/coal wash | Municipal & industrial sludge, paper, food | Specialty industrial |
(Dosage ranges are indicative—confirm by jar test.)
Common Uses of Polyacrylamide PAM
Water & wastewater treatment. A core use of polyacrylamide water treatment is boosting flocculation, sedimentation and clarification. A common sequence: a PAC coagulant first destabilizes fine particles, then PAM builds large flocs—cutting turbidity, suspended solids and sludge volume.
Sludge dewatering. PAM binds sludge particles and drives water release ahead of belt filter presses, centrifuges, screw presses and plate-and-frame presses. Correct dosing lowers cake moisture and disposal cost; over-dosing produces sticky, poorly structured sludge.
Textile & paper-mill wastewater. In textile effluent (dyes, surfactants, solids) PAM improves post-coagulation clarification. In paper-mill wastewater it helps remove fibers and fillers and can aid retention and drainage.
Mining & mineral processing. PAM settles fine mineral particles, clarifies process water, and improves tailings-water recovery and sedimentation efficiency.
How to Choose the Right PAM Grade
Don’t pick on price or molecular weight alone—higher MW is not automatically better. Match the grade to the water and the goal:
- Wastewater type — municipal sludge vs. textile vs. mining vs. paper each behave differently.
- Particle characteristics — organic vs. mineral vs. mixed loads flocculate differently.
- Charge type — select APAM / CPAM / NPAM from the water’s charge condition.
- Molecular weight — higher MW improves bridging but raises viscosity and slows dissolution.
- Dosage economics — the best grade hits your target at a reasonable dose (see cost note below).
- Equipment — centrifuges, filter presses and clarifiers need different floc strength and size.
Why Jar Testing Matters
Jar testing is the most reliable way to select PAM, letting you compare grades under your real wastewater. Observe:
- Floc size and strength
- Settling speed and supernatant clarity
- Sludge volume and dewatering performance
- Required dosage
A small change in grade can cause a large change in results—so request samples and jar-test before any bulk order.
Common Mistakes When Buying PAM
- Buying on price per ton. A cheaper polymer often needs a much higher dose, raising total treatment cost. Compare cost-per-treated-volume, not sticker price.
- One grade for every stream. A mining-water grade rarely dewaters sludge well.
- Poor dissolution. Fast dumping or bad mixing creates fish-eyes, wastes product and cuts performance—follow the 0.1–0.3% / slow-feed / full-hydration rule above.
Final Thoughts
PAM is a highly effective polymer across water treatment, sludge dewatering, mining, textile and paper applications—but performance hinges on the right grade. For most buyers, the smart path is to jar-test anionic, cationic and nonionic samples and compare floc formation, dewatering, operating stability and total cost.
Jinxiang Chemical supplies APAM, CPAM and NPAM for water and wastewater treatment, sludge dewatering, textile, paper-mill and mining applications.
Get free selection help: Send us your wastewater conditions (type, pH, TSS, current dosage, equipment) and we’ll recommend grades.
FAQ
What is PAM used for?
As a flocculant, wastewater-treatment polymer, sludge-dewatering polymer and solid-liquid separation aid across many industries.
What is the difference between anionic and cationic polyacrylamide?
Anionic PAM suits inorganic/mineral wastewater; cationic PAM suits organic wastewater and sludge dewatering.
Can PAM be used with PAC?
Yes, PAC coagulates (destabilizes fine particles) and PAM flocculates (builds large flocs); they’re frequently used together.
How do I choose the right PAM polymer?
It depends on wastewater type, particle charge, pH, sludge characteristics and equipment—jar test before bulk purchase.
How much PAM should I dose?
Typically 0.5–3 ppm for clarification and 3–10 kg per ton of dry solids for dewatering—confirm by jar test, since real dosage varies with water quality.