Cationic Polyacrylamide for Sludge Dewatering | Henan Saifu
Municipal and industrial sludge dewatering requires efficient solid-liquid separation. Cationic Polyacrylamide (CPAM) supplied by Henan Saifu (Henan Saifu.com) is a high-molecular-weight synthetic copolymer carrying positive amine functional groups.
During sludge conditioning, positive charges neutralize negative surface sites on suspended organic colloids and microbial cells. This charge neutralization collapses hydration layers, allowing polymer chains to bridge multiple particles into dense, shear-resistant flocs that release interstitial water under mechanical pressure.
Cationic PAM Grades for Sludge Treatment
Henan Saifu manufactures tailored CPAM grades classified by charge density and molecular weight to match varying sludge organic fractions.
|
Grade Designation |
Molecular Weight (Million Daltons) |
Cationic Charge Density (%) |
Primary Sludge Application |
|
PC-310 |
10 - 12 |
10 - 20 (Low) |
Inorganic-heavy primary municipal sludge; Paper mill primary sludge |
|
PC-330 |
13 - 15 |
30 - 40 (Medium) |
Mixed municipal secondary biological sludge; Food processing wastewater |
|
PC-350 |
16 - 18 |
50 - 60 (High) |
Highly organic secondary waste-activated sludge (WAS); Petrochemical sludge |
Flocculation & Water Release Mechanism
Charge Neutralization
Polymer active sites adsorb onto negatively charged colloidal particles, reducing zeta potential.
Bridging Effect
Long-chain polymer molecules bind multiple suspended particles simultaneously, forming large three-dimensional micro-flocs.
Capillary Water Release
Dense floc structures trap free water within interstitial spaces, releasing water rapidly under mechanical shear without breaking polymer chains.
Technical Specifications
|
Parameter |
Specification |
|
Appearance |
White free-flowing powder |
|
Solid Content |
≥ 88% |
|
Dissolution Time |
≤ 60 minutes in clean water at 20°C |
|
Recommended Dosing Concentration |
0.1% to 0.5% stock solution |
|
Residual Monomer |
< 0.05% |
|
Packaging |
25 kg multi-wall paper-plastic bags with inner polyethylene lining; 750 kg jumbo bags available upon request. |
Sludge Dewatering Applications
Municipal WWTP: Conditioning of digested and undigested secondary waste-activated sludge (WAS) prior to final disposal.
Pulp & Paper: Dewatering primary clarifier sludge and deinking sludge with high mineral filler content.
Food & Beverage: Handling organic-rich biological sludge from slaughterhouses, breweries, and dairy facilities.
Petrochemical: Breaking oil-in-water emulsions and conditioning oily sludge from DAF units and biological basins.
Selection by Sludge Type
Municipal Sludge: Requires medium molecular weight (12-15 million) and moderate cationic charge (30-40%) to handle fluctuating volatile suspended solids (VSS).
Industrial Sludge (High Oil/Fat): Requires high charge density (40-60%) to break persistent lipid-water emulsions.
Inorganic Mineral Sludge: Requires low charge density (10-20%) with ultra-high molecular weight to promote rapid sedimentation.
Belt Filter Press, Centrifuge & Screw Press
Decanter Centrifuge: Operates at high gravitational forces (2000--3000×g). Requires high molecular weight CPAM (PC-350) to form high-tensile flocs resisting high shear stress inside the bowl.
Belt Filter Press: Relies on gravity drainage and progressive pressure zones. Requires resilient flocs forming a porous cake structure for rapid filtrate drainage without belt blinding.
Multi-Disk Screw Press: Operates at low rotational speeds with high internal pressure. Requires steady polymer dosing to form compact, non-sticky flocs that maintain smooth sludge discharge.
Polymer Preparation & Dosing System
Wetting: Feed dry powder through an automated multi-stage feeder into the wetting cone to disperse particles before contact.
Dissolution: Maintain gentle mechanical agitation (300--400 rpm) in a primary tank for 45 to 60 minutes at ambient water temperature (10°C to 30°C). Avoid high-shear centrifugal pumps.
Aging: Transfer stock solution (0.2%) to an aging tank for complete polymer chain unwinding.
Secondary Dilution: Dilute down to 0.05%--0.1% inline immediately prior to the sludge injection point.
Jar Test & Dewatering Performance Testing
Measure 500 mL of representative liquid sludge into a beaker.
Add a measured volume of 0.1% CPAM test solution using a graduated syringe.
Flash mix at 200 rpm for 10 seconds, then flocculate at 40 rpm for 30 seconds.
Evaluate supernatant clarity, floc size, settling velocity, and free-drainage release time through a standard 100 mesh screen.
Production, Quality Control & Supply
Manufacturing Standards: Produced under ISO 9001 and ISO 14001 systems. Full regulatory compliance support for REACH in European markets.
Production Process: Aqueous solution polymerization under controlled temperature to ensure uniform molecular weight distribution.
Drying & Milling: Indirect steam drying followed by mechanical grinding and pneumatic classification to guarantee uniform particle size (20--80 mesh).
Batch Traceability: Every lot undergoes internal testing for solid content, intrinsic viscosity, and residual monomer. Each bag features a distinct lot code linked to archived laboratory retention samples and downloadable Certificate of Analysis (COA) records.
FAQ
Q: How do I determine whether to use cationic, anionic, or non-ionic PAM?
A: Sludge surfaces carry a negative electrical charge due to microbial cell walls. Cationic PAM neutralizes these negative sites, making it mandatory for municipal and organic industrial sludges. Anionic PAM is reserved for positively charged inorganic mineral slurries (e.g., metal mining tailings).
Q: What causes polymer solution to lose viscosity during storage?
A: Shear degradation from high-speed centrifugal pumps, bacterial degradation in dilute stock solutions stored beyond 48 hours, and exposure to iron or copper piping will break polymer chains. Prepare fresh stock daily and use progressive cavity or peristaltic pumps.
Q: Why are filter press cakes still wet despite increasing polymer dosage?
A: Over-dosing cationic polymer causes charge reversal, turning sludge particles positive and causing redepsersion. This creates a sticky, gel-like cake that blocks filter cloth pores. Perform a jar test to verify optimal stoichiometric demand.
Q: What is the shelf life of solid cationic polyacrylamide powder?
A: Unopened bags stored in a cool, dry, well-ventilated indoor warehouse (5°C to 30°C) remain stable for up to 24 months. Keep bags elevated off concrete floors on pallets to prevent moisture absorption.
Q: Can Henan Saifu supply custom grades?
A: Yes. For specialized industrial waste streams that standard commercial grades cannot condition effectively, our laboratory formulates customized copolymer ratios based on customer-supplied sludge samples.
Q: What documentation is provided with commercial shipments?
A: Each shipment includes a Certificate of Analysis (COA) specifying batch-specific solid content and molecular weight metrics, alongside a Material Safety Data Sheet (MSDS) and commercial shipping documents.
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