What Happens If PAM Dosage Is Too High?

What Is Polyacrylamide (PAM) and Why Do We Use It?

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 works mainly through polymer bridging, connecting small flocs into larger and denser aggregates, improving sedimentation 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

   ● Bridging points are reduced

   ● Flocs break apart instead of settling

👉 This leads to poor settling and higher turbidity.

2️⃣ Poor Sludge Dewatering Performance

In sludge dewatering systems:

   ● Overdosed PAM creates loose flocs

   ● Sludge cakes contain higher moisture

   ● Filter cloths and pipes 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

   ● Does not improve treatment efficiency

   ● May negatively affect downstream filtration

What Is the Normal PAM Dosage?

There is no universal PAM dosage, but typical reference ranges are:

👉 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 dewatering

Food Processing & Livestock Wastewater

Recommended combination:

   ● pH adjustment or demulsifier

   ● PAC + PAM

   ● Activated carbon if needed

Our Professional Recommendation

Based on our field experience, we always advise:

   ● Avoid blindly increasing PAM dosage

   ● Optimize coagulant selection first

   ● Choose the correct ionic type of PAM

   ● Determine the optimal dosage window by 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 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, and polymer type all play key roles.