As a professional water treatment chemical manufacturer, we have seen that polyacrylamide (PAM) is one of the most effective, yet frequently misused, flocculants in wastewater treatment. PAM mainly works through polymer bridging, connecting small flocs into larger and denser aggregates. This improves sedimentation efficiency and sludge dewatering performance.
However, more PAM does not mean better results.
Side Effects of Excessive PAM Dosage
1️⃣ Floc Restabilization and Turbid Effluent
When PAM dosage is too high:
- Polymer chains fully coat floc surfaces
- Effective bridging points are reduced
- Flocs become unstable and break apart
👉 This leads to poor settling and increased effluent turbidity.
2️⃣ Poor Sludge Dewatering Performance
In sludge dewatering systems:
- Overdosed PAM forms loose and fluffy flocs
- Sludge cakes retain higher moisture
- Filter cloths and pipelines clog more easily
👉 Operating costs increase instead of decreasing.
3️⃣ Higher Chemical Cost With No Efficiency Gain
PAM is a high-value polymer:
- Excess dosage increases chemical consumption
- Treatment efficiency does not improve
- Downstream filtration performance may decline
👉 Overdosing directly reduces cost-effectiveness.
What Is the Normal PAM Dosage?
There is no universal PAM dosage, but typical reference ranges are:
| Application | PAM Dosage |
|---|---|
| Coal washing wastewater | 1–5 g/m³ |
| Industrial wastewater | 0.5–3 g/m³ |
| Sludge dewatering | 2–6 kg / ton DS |
| Food & slaughterhouse wastewater | 1–4 g/m³ |
👉 Jar tests are strongly recommended before full-scale dosing.
How to Properly Combine PAM With Other Chemicals?
Coal & Sand Washing Wastewater
Recommended combination:
- PAC or PFS
- Anionic PAM as flocculant aid
Municipal Wastewater & Sludge
Recommended combination:
- PAC or aluminum sulfate
- Cationic PAM for sludge dewatering
Food Processing & Livestock Wastewater
Recommended combination:
- pH adjustment or demulsifier
- PAC + PAM
- Activated carbon if necessary
Our Professional Recommendation
Based on extensive field experience, we always advise:
- Do not blindly increase PAM dosage
- Optimize coagulant selection first
- Choose the correct ionic type of PAM
- Determine the optimal dosage window through testing
👉 Correct PAM dosing means lower cost and stable performance.
FAQ
Q1: Is overdosed PAM harmful to treated water?
A1: It is not toxic, but it may cause turbidity increase and COD rebound.
Q2: Can PAM be used alone?
A2: Not recommended. PAM works best with coagulants such as PAC or PFS.
Q3: Why does PAM performance vary so much?
A3: Water quality, pH, mixing conditions, and polymer type all play key roles.
Article Summary
Excessive PAM dosage does not improve wastewater treatment performance. Instead, it can cause floc restabilization, poor sludge dewatering, higher operating costs, and unstable system operation. Proper PAM selection, correct chemical combination, and dosage optimization through testing are the keys to achieving stable, cost-effective treatment results.
