Key Tips for PAM Dosing with TNW Co., Ltd Screw Presses

Key Tips for PAM Dosing with TNW Co., Ltd screw presses

Many users purchase TNW screw presses yet face poor sludge dewatering: turbid filtrate, sticky wet sludge cake, high chemical consumption and frequent stack ring blockages. Over 90% of such issues stem from improper PAM selection, preparation, dosing and equipment linkage. Based on thousands of on-site commissioning cases from TNW Co., Ltd, we summarize practical guidelines to stabilize dewatering performance and cut chemical costs.

1. Select Proper PAM Model First

Incorrect PAM renders dosage adjustment useless.

Municipal, food and slaughter organic sludge: Cationic PAM (higher ionic degree for high organic content). Free sludge sample testing and matching available at TNW.

Sand washing, mining and river dredging inorganic slurry: Anionic PAM for fast bridging flocculation and complete mud-water separation.

Printing and oily chemical sludge: Add PAC first to neutralize charges, then PAM to form dense flocs; reverse order invalidates treatment.

Warning: Mixing cationic and anionic PAM neutralizes flocculation activity and wastes chemicals entirely.

2. Standard PAM Preparation to Avoid Undissolved Lumps

TNW three-chamber integrated dosing units deliver optimal chemical activity; simple mixing barrels easily produce insoluble agglomerates.

Strict concentration: 0.1%–0.3% (1–3 kg PAM per ton of clean water). Over-concentrated solution clogs pumps; dilute solution weakens flocculation.

Fill water and start stirring before slowly feeding PAM powder along the water vortex. Never dump whole bags at once to prevent hard undissolved lumps that damage metering pumps and pipelines.

Cure for 30–60 minutes. Optimal water temperature: 10–40°C. Water over 50°C breaks polymer chains and halves efficiency. Use heating insulation on dosing units in cold winter.

Use prepared solution within the same day; activity declines sharply after 24 hours of standing.

3. Correct Dosing Point & Mixing Control Determine Floc Quality

Dose PAM into the pipeline mixer/flocculation tank at the screw press inlet. Allow 1–3 minutes full mixing before sludge enters the main unit. Direct dosing at sludge inlet causes incomplete mixing, fine flocs and turbid filtrate.

Judge proper dosage by floc appearance: ideal flocs are 0.5–1 cm, dense and intact with clear outlet water.

Fine loose flocs + cloudy filtrate: Insufficient PAM; increase metering pump frequency gradually.

Sticky stringy flocs stuck on stack rings: Excessive PAM causing blockages; reduce dosage.

Adjust dosing rate with fluctuating sludge concentration. TNW automatic linked dosing units auto-regulate feed based on sludge flow to eliminate frequent manual adjustment.

4. Synchronized Operation of Screw Press & PAM Dosing Unit

All TNW matched sets are pre-calibrated at factory; maintain synchronized operation daily.

Startup sequence: Start dosing system to prepare cured liquid first, then sludge feed pump and screw press. Shutdown sequence reverse: Stop sludge feed, run press empty to discharge residual sludge, then close metering pumps to avoid dried chemical blockages between rings.

Keep liquid level linkage enabled. Auto preparation stops chemical shortage and raw sludge direct feeding which leads to massive sludge leakage.

Calibrate metering pumps weekly to avoid unstable dosing and inconsistent dewatering results.

5. Routine Maintenance to Cut Chemical Waste & Equipment Failures

Flush dosing tanks and pipelines weekly to remove settled chemical lumps that jam pumps and screw presses.

Store PAM powder in sealed, dry, shaded warehouses. Moist powder agglomerates severely when dissolved.

Avoid arbitrary screw speed increase: High rotation speed shears formed flocs and raises cake moisture even with sufficient PAM.

For persistent turbid filtrate or wet cake, check PAM type, curing time and mixing sufficiency before raising dosage. Blindly adding PAM only inflates long-term operation costs.

6. Supplementary Tips for Special Working Conditions

Sandy sludge: Use matched anionic PAM and tungsten carbide coated spiral for wear resistance and shear-resistant flocs.

Acid/alkaline chemical sludge: Adopt full 316L stainless steel dosing units for corrosion resistance. Neutralize sludge pH beforehand; extreme pH severely weakens PAM performance.

24-hour continuous operation: Automatic linked integrated sets reduce manual preparation and adjustment, ensuring stable compliance all day long.

Conclusion

Screw press dewatering performance depends equally on hardware quality and standardized PAM selection, dissolution and precise dosing. Many operators overlook dosing details, resulting in high chemical expenditure, frequent blockages and unqualified discharge.

TNW Co., Ltd supplies complete matched packages of TNW screw presses and integrated PAM dosing units with factory pre-linkage debugging. Our technicians provide on-site hands-on training for chemical preparation and adjustment. Send sludge samples for free lab testing to obtain customized PAM dosing schemes if you are unsure of the suitable model and optimal dosage ratio.