We supply PAM to municipal wastewater plants in Brazil, Southeast Asia, and the Middle East. The biggest mistake we see? Plants buying generic PAM and using the same grade for every stage. A 150,000 m³/day plant in São Paulo switched from one-grade-fits-all to stage-specific PAM and saved $158,000 in the first year. Here is exactly how they did it — and how you can do the same.
Where PAM Fits in Your Treatment Train
| Stage | PAM Type | MW | Dosage | What It Does |
|---|---|---|---|---|
| Primary clarification | APAM | 10-15M | 0.5-1.5 ppm | Bridges suspended solids into settleable flocs |
| Secondary clarification | CPAM | 8-12M | 0.5-2.0 ppm | Neutralizes activated sludge charge, speeds settling |
| Sludge thickening | CPAM | 10-15M | 2-5 ppm | Doubles underflow solids (3% → 6-8%) |
| Sludge dewatering | CPAM | 8-12M | 5-18 g/kg DS | Creates shear-resistant flocs for belt press/centrifuge |
Primary Clarification: APAM
Raw wastewater hits your primary clarifier at 200-500 mg/L TSS. Without polymer, you get 50-60% solids capture and 2-4 hour settling time. Add 0.5-1.5 ppm of our APAM (10-15M MW, 20-30% hydrolysis) and capture jumps to 70-80% in under an hour.
Why anionic here? Raw sewage particles are negatively charged, but APAM works through bridging — the long polymer chains physically connect particles into larger flocs. Charge neutralization is not the mechanism at this stage.
For projects like this, our CPAM with 40-60% charge density delivers consistent results with factory-direct pricing.
For projects like this, our high molecular weight anionic PAM delivers consistent results with factory-direct pricing.
We produce 7 APAM grades from 6M to 28M molecular weight. For primary clarification, our 12M grade with 25% hydrolysis is the workhorse — it dissolves in under 60 minutes and works across pH 6.5-8.0 without adjustment.
Secondary Clarification: CPAM
After biological treatment, your activated sludge needs to settle fast. Slow settling means turbid effluent, sludge carryover, and compliance headaches. CPAM at 0.5-2.0 ppm speeds settling by 40-60%.
Activated sludge is negatively charged (bacterial cell walls + EPS). Our CPAM neutralizes that charge. We recommend 40-60% charge density and 8-12M MW for this stage. Higher charge = faster settling, but overdosing reverses the charge and makes things worse.
The key insight from our Brazilian client: they were using 50% charge CPAM year-round. Summer sludge (higher organic load, more EPS) needed 65% charge. We custom-formulated a summer grade and a winter grade. Result: effluent TSS dropped from 25 mg/L to 8 mg/L.
Sludge Dewatering: Where the Real Money Is
Dewatering is 40-60% of your total sludge handling cost. Every 1% reduction in cake moisture saves 5-8% in disposal costs. This is where PAM selection matters most.
| Your Equipment | CPAM Charge | MW | Dosage | Expected Cake |
|---|---|---|---|---|
| Belt filter press | 40-60% | 8-10M | 5-12 g/kg DS | 75-80% |
| Centrifuge | 60-80% | 10-12M | 8-15 g/kg DS | 72-78% |
| Screw press | 60-80% | 10-12M | 10-18 g/kg DS | 70-76% |
Centrifuges need higher charge and higher MW because the shear forces inside are brutal. A floc that works perfectly in a jar test can fall apart in a centrifuge if the MW is too low. We test every batch for shear resistance — not just viscosity.
Real Numbers: Brazil Municipal WWTP
150,000 m³/day Plant — Before & After
The Problem
Client used a European brand CPAM. During rainy season, influent fluctuated wildly. Their belt press kept clogging. Cake moisture stuck at 82%. They were paying $54,000/year in flocculant and $180,000/year in sludge disposal.
What We Did
Analyzed their sludge samples (free — we do this for every new client). Found their sludge VSS/TSS ratio swings from 55% (dry season) to 72% (rainy season). One PAM grade cannot handle that range. We formulated two custom grades: 45% charge for dry season, 65% charge for rainy season. Also increased MW from 8M to 10M for better shear resistance in their belt press.
Results (6 months)
Why Generic PAM Fails in Municipal Plants
Most PAM suppliers sell you one grade and call it a day. Here is why that does not work:
- Seasonal variation. Summer sludge has 15-20% more organic content than winter sludge. Same PAM grade will underdose in summer and overdose in winter.
- Equipment mismatch. A belt press needs different floc characteristics than a centrifuge. Using centrifuge-grade PAM in a belt press wastes 30-40% of your chemical.
- Batch inconsistency. Trading companies source from whoever is cheapest this month. Batch 1 works great, batch 2 is garbage. We retain samples from every batch for 24 months — full traceability.
How We Work With Municipal Plants
- Free sludge analysis. Send us 500mL of your sludge. Our lab (5 full-time technicians, advanced testing equipment) analyzes VSS/TSS, organic content, pH, and particle charge. Results in 3-5 days.
- Custom formulation. Based on your sludge data and equipment type, we recommend specific grades. If your sludge is unusual, we adjust monomer ratios to match.
- Free samples. 2-5kg of each recommended grade, enough for proper jar tests and pilot runs.
- Remote commissioning. Video call with our technical team during your first full-scale trial. We walk you through dosing optimization in real time.
- Seasonal adjustment. We ship different grades for different seasons if your sludge characteristics change. No extra charge for the formulation work.
Our Municipal-Grade PAM Specs
| Parameter | Specification |
|---|---|
| Solid content | ≥92% |
| Dissolution time | ≤90 minutes |
| Residual monomer | ≤0.05% (500 ppm) |
| Insoluble matter | ≤0.1% |
| MW tolerance | ±0.5M (e.g., 10M grade = 9.5-10.5M) |
| CPAM charge range | 5-70% (10 grades available) |
| APAM MW range | 6-28M (7 grades available) |
Certifications: ISO 9001, ISO 14001, ISO 45001, NSF. Every batch goes through our 3-tier QC: in-process monitoring → batch testing → pre-shipment inspection.
Pricing (2026, FOB China)
- APAM (primary clarification): $1,200-1,600/MT
- CPAM 40-60% charge (belt press): $1,600-2,000/MT
- CPAM 60-80% charge (centrifuge): $1,900-2,400/MT
MOQ: 500kg first order. FCL (20MT+): 10-12% discount. Annual contract (200MT+): 15-18% discount. Delivery: 7-10 days standard, 3-5 days urgent (stock items).
Want to test with your sludge?
Send us your sludge data (or ship us a sample — we pay return shipping). We will recommend grades, send free samples, and support your jar tests via video call.
WhatsApp: +86 150-0381-8598 · Email: info@chinapolyacrylamide.com