Applications of Cross-Linked Cationic Polyacrylamide

1. Sludge Dewatering (Municipal & Industrial Wastewater)

This is the most common application.
Cross-linked CPAM forms rigid, dense, shear-resistant flocs, which improves dewatering on:

• belt filter presses

• screw presses

• plate-and-frame presses

• centrifuges

Benefits:

• Higher solids content in the final cake

• Reduced polymer consumption compared to linear CPAM

• Stable performance even at high shear zones

• Strong resistance to floc breakage

This makes it ideal for difficult sludges such as:

• oily sludge

• chemical & petrochemical sludge

• paper mill biological sludge

• textile sludge

• municipal activated sludge with low solids

2. Sludge Conditioning Under High-Shear Systems

Some wastewater treatment systems (especially centrifuges) expose flocs to intense shear.
Linear CPAM flocs can break easily; cross-linked CPAM forms stronger floc structures due to its 3D network.

Used in:

• high-speed decanter centrifuges

• cyclone thickening units

• anaerobic digester sludge thickening

3. Oil & Gas Industry (Enhanced Oil Recovery and Drilling Fluids)

a. Enhanced Oil Recovery (EOR)

Cross-linked cationic PAM provides very high viscosity and stability in harsh reservoirs.
It is used in:

• polymer flooding

• mobility control

• profile modification

Its cross-linked structure slows down degradation, giving longer residence time in the reservoir.

b. Drilling Fluids

Used as:

• viscosifier

• fluid-loss reducer

• encapsulating agent for shale stabilization

The 3D polymer network helps maintain viscosity under high temperatures and salinity.

4. Papermaking Industry

Cationic polymers are widely used in papermaking; cross-linked CPAM serves as:

• retention & drainage aid

• dry-strength resin

• fines bonding agent

Advantages:

• Better retention of fines, fillers, and fibers

• Improved paper strength

• Faster drainage on wire section

Cross-linked CPAM performs better than linear CPAM in high-speed paper machines.

5. Mineral Processing and Solid–Liquid Separation

Although anionic flocculants dominate mining, cross-linked CPAM is used when minerals or tailings are negatively charged and require strong cationic bridging, especially in:

• kaolin clay refining

• phosphate beneficiation

• rare earth processing

• tailings thickening for specific mineral slurries

It provides faster settling and sturdier flocs in high-solid slurries.

6. Treatment of High-Organic-Load Wastewater

Cross-linked CPAM is effective where sludge contains large amounts of:

• proteins

• fats & oils

• cellulose

• organics from food or fermentation plants

Its higher charge density and 3D structure improve:

• coagulation of colloids

• rapid formation of compact sludge

• reduction of sludge volume

Industries include:

• breweries

• food and beverage

• slaughterhouses

• starch processing

• pharmaceutical wastewater

7. Process-Water Treatment in Chemical Plants

Cross-linked CPAM is used for flocculation in environments with strong chemicals, where ordinary polymers degrade quickly.
Applications include:

• polyvinyl chloride (PVC) plant wastewater

• dye & pigment wastewater

• surfactant and detergent plant effluent

• solvent-containing wastewater

The cross-linked structure provides resistance to solvent attack and high pH variation.

8. Dewatering of Difficult-to-Treat Industrial Sludges

Many industrial sludges contain oils or chemicals that reduce bonding with linear polymers.
Cross-linked CPAM is used for:

• oily refinery sludge

• tar-rich sludge

• petrochemical wastewater

• paint and pigment sludge

• metal-finishing sludge

Its network structure allows better entrapment and binding of colloids and oily particles.

Why Cross-Linked CPAM Is Used Instead of Linear CPAM

1. Stronger, more stable flocs

The cross-linked architecture creates rigid 3D flocs that do not collapse under shear.

2. Higher resistance to mechanical stress

Critical for centrifuges and high-turbulence systems.

3. Better tolerance to salinity, heat, and chemicals

Cross-linking increases molecular stability.

4. Lower dosage due to better bridging efficiency

5. Better performance with oily or organic-heavy sludges

Summary — Main Applications of Cross-Linked Cationic Polyacrylamide