Plate and Screw Sludge Dewatering Machine for Surplus Sludge System

The Plate and Screw Sludge Dewatering Machine is a type of equipment used for dewatering surplus sludge, commonly found in wastewater treatment processes. It combines the principles of a plate filter press and a screw press to efficiently separate liquid from solids, reducing the volume of sludge for easier disposal or further processing.

How It Works

The sludge is pumped into a series of plates and frames, where pressure is applied to squeeze out water. The solids form a cake between the plates, while the liquid (filtrate) is discharged. This method is highly effective for achieving high dryness levels, often up to 30-80% solid content.

The plates are typically made of durable materials like stainless steel, and the process can be automated for continuous operation.

A slowly rotating screw (typically ~5 RPM) moves the sludge through a cylindrical screen or drum filter. The screw applies increasing pressure as it conveys the sludge, forcing water out through the screen while forming a dewatered sludge cake.

The screw press is designed to handle a wide range of sludge concentrations (e.g., 2000 mg/L to 50,000 mg/L) and is particularly effective for oily or difficult-to-dewater sludges.

In some designs, the plate and screw systems are integrated or used sequentially. For example, the plate press may be used for initial dewatering, followed by the screw press for further compaction and drying.

The equipment often includes a flocculation tank where polymers are added to aggregate sludge particles, enhancing solid-liquid separation.

Municipal Wastewater Treatment: Dewatering surplus activated sludge or digested sludge from aerobic/anaerobic processes. The resulting cake typically has 15-20% dry solids for municipal sludge, reducing disposal costs.

Industrial Wastewater: Effective for sludge from industries like food and beverage, petrochemical, paper, and pharmaceuticals, where sludge characteristics vary widely.

Other Uses: Can be applied to manure treatment, DAF (Dissolved Air Flotation) sludge, or even chemical industry processes like synthetic rubber production.

Advantages

High Efficiency: Achieves significant volume reduction (up to 90% less sludge volume) and high cake dryness, lowering transportation and disposal costs.

Low Energy Consumption: Screw presses operate at low speeds, reducing power usage compared to centrifuges (1/8 to 1/20 of centrifuge energy).

Clog-Free Design: The screw press’s moving rings or self-cleaning mechanisms prevent blockages, making it suitable for oily or sticky sludges.

Compact and Automated: Requires less space than traditional belt presses and can run automatically with PLC control, minimizing operator intervention.

Eco-Friendly: Low water and energy usage, plus the ability to recycle filtrate, contribute to sustainable operations.

Limitations

Sludge Variability: The final cake’s dryness depends on sludge quality (e.g., volatile solids content). Organic sludges may achieve lower dryness than mineral sludges.

Initial Cost: Equipment can be expensive, though long-term savings on disposal and energy offset this.

Maintenance: While screw presses require less maintenance than belt presses, plate filter presses may need regular cleaning of plates and cloths.

Specific Features

Materials: Typically constructed with stainless steel (SS304 or SS316) for corrosion resistance.

Capacity: Available in various sizes, from small (100 kld) to large (800 kg/h DS), depending on the model.

Optional Features: Some models include pre-thickening modules, automatic spray systems, or filtrate recycling for enhanced performance.

Conclusion

The Plate and Screw Sludge Dewatering Machine is an efficient, versatile solution for managing surplus sludge in municipal and industrial settings. Its ability to produce a dry, compact sludge cake while minimizing energy and water use makes it a cost-effective and sustainable choice.