What is the Difference Between PAC and PAM? How to Choose?

In water treatment applications, PAC (Polyaluminium Chloride) and PAM (Polyacrylamide) are two most commonly used flocculants, but many users are confused about their differences and suitable applications.

As a professional water treatment chemicals manufacturer, we will explain the differences between PAC and PAM in detail from multiple dimensions including composition, working mechanism, application scenarios, and guide you to make the right selection based on actual needs.

 

Basic Concepts of PAC and PAM

PAC (Polyaluminium Chloride)

-Chemical Name: Polyaluminium Chloride

-Appearance: Yellow or brown powder/liquid

-Main Component: [Al2(OH)nCl6-n]m

-pH Range: 3.5-5.0 (1% aqueous solution)

PAM (Polyacrylamide)

-Chemical Name: Polyacrylamide

-Appearance: White powder/granules

-Main Types: Cationic, Anionic, Non-ionic

-Applicable pH Range: 5-14 (depending on type)

 

 Five Key Differences Between PAC and PAM

Comparison Item	PAC	PAM
Mechanism	Mainly charge neutralization	Mainly adsorption bridging
Molecular Weight	Relatively low (thousands)	Extremely high (millions to tens of millions)
Dissolution Rate	Fast (5-10 minutes)	Slow (40-60 minutes aging required)
Suitable pH	Wide range (optimal 5-9)	Type dependent (cationic optimal 5-7)
Residue	Aluminum ion residue	Nearly no residue

 

How to Choose Between PAC and PAM?

Based on Water Quality Characteristics

-High Turbidity Water: PAC+PAM combination works best

-Low Turbidity High Color Water: PAC preferred

-Oily Wastewater: Cationic PAM works better

-Sludge Dewatering: Must use cationic PAM

Based on Treatment Process

-Pretreatment Stage: Usually PAC alone

-Advanced Treatment: PAC+PAM combination recommended

-Sludge Thickening: Special cationic PAM required

Economic Considerations

-PAC has lower unit price but higher dosage

-PAM has higher unit price but lower dosage (typically 0.1-1ppm)

-Combined use can reduce total treatment cost by 15-30%

 

Usage Precautions

PAC Usage Tips

-Optimal dosage typically 10-50mg/L

-Recommended preparation concentration 5-10%

-Avoid direct mixing with alkaline substances

PAM Usage Tips

-Must be fully dissolved (recommended 0.1-0.3% concentration)

-Stirring speed control at 60-200rpm

-Prepare fresh solution (storage <24 hours)

Combination Usage Techniques

-Add PAC first, then PAM after 30-60 seconds interval

-Optimal mass ratio typically PAC:PAM=10:1 to 20:1

-Jar test required to determine best ratio

 

Frequently Asked Questions

Q: Can we use only PAM without PAC?
A: May work for low turbidity wastewater but ineffective for high turbidity water with higher cost.

Q: Why do “fish eyes” appear when dissolving PAM?
A: Indicates insufficient dissolution, need to improve dissolution process (e.g. using automatic dosing device).

Q: Which is more environmentally friendly, PAC or PAM?
A: PAM is more eco-friendly (no metal ion residue) but must select products meeting GB17514-2017 standard.