PWTech Volute Dewatering Press

Volute Dewatering Press: Dewater Sludge Efficiently

What is unique about the Volute Dewatering Press?

Volute Dewatering Press: Dewater Sludge Efficiently
Volute Dewatering Press: Dewater Sludge Efficiently

The PWTech Volute Dewatering Press is an improved version of the traditional screw press. The conventional screw press with perforated holes often clogs, requiring manual cleaning and downtime. The Volute Dewatering Press eliminates this issue with its innovative self-cleaning design. Fixed and moving rings continuously scrape the filter mesh, allowing uninterrupted dewatering.

Benefits of the Volute Press:

  • High cake solids and capture rates: Achieve drier sludge cake.
  • Simple and reliable: Robust design with minimal moving parts for easy operation and maintenance.
  • Automated operation: Requires minimal operator attention, saving time and labor costs.
  • Low power consumption: Energy-efficient compared to other dewatering technologies.
  • Low total cost of ownership: Reduced power, labor, and maintenance costs.
  • Low noise, low odors, small footprint:┬áSuitable for space-constrained environments.


Dewatered Sludge from a PW Tech Volute Dewatering Press
Dewatered Sludge from a PW Tech Volute Dewatering Press
  • Municipal sludges from wastewater treatment plant
  • Industrial sludges including food processing, paper production and oily sludges
  • Potable water treatment plant sludges

Performance and Capacity:

The amount of sludge dewatered depends on factors like sludge type, desired cake solids, and press size. Pilot testing with PWTech’s trailers helps determine the best operating parameters for your specific needs.

Operator Time Required:

The Volute Dewatering Press offers automatic, unattended operation and requires little operator attention. The only operator requirement is daily visual inspections and more comprehensive quarterly and yearly inspections.

Operating Costs:

The cost of operation includes power, overhaul costs, labor, and chemicals. These costs vary significantly for every installation. The following table is a guide with low and high cost/ton of dry solids processed:

ItemLowHighUnitUnit CostLow-Cost EstHigh-Cost Est
Chemicals1030#/ton dry solids$5.00/pound (polymer)$50.00$150.00
Labor is estimated at 1 hour/week. Assuming a labor rate of $30/hour, the labor cost is $1,560/year.

Power Costs:

Video of the Volute Dewatering Press

The Volute Press is an energy-efficient dewatering technology compared to other options like centrifuges or belt filter presses. The Volute Press typically uses about 5 kW hours of power per ton of dry sludge, significantly lower than the energy consumption of other technologies. For example, centrifuges and belt filter presses can require at least 100 kW hours and 50 kW hours of power, respectively, not including additional energy consumed by pre-thickening equipment, wash water pumps, compressors, etc. Therefore, the Volute Press offers a cost-effective solution in terms of energy consumption.

Chemical Used:

Approximately 95% of Volute Dewatering Press installations use polymer only. Polymers cause flocculation of the sludge solids to improve dewatering performance. Generally, the amount of polymer used will vary between 10 and 30 lbs/ton of dry solids dewatered, similar to a centrifuge or belt filter press.

Operation and Maintenance:

The Volute Press is designed for automatic operation and requires minimal maintenance. The main wear item, the moving rings, can be easily replaced in a matter of hours.

PWTech Volute Dewatering Press Pilot Test Trailers
PWTech Volute Dewatering Press Pilot Test Trailers

Pilot Testing:

Before investing, test the Volute Press with PWTech’s pilot trailers to evaluate its performance on your specific sludge. This helps ensure the press meets your needs and delivers desired results.

Contact Envirep

Envirep/TLC serves the municipal and industrial water and wastewater market in Pennsylvania, New Jersey, Maryland, Delaware, the District of Columbia, Virginia, and West Virginia.

Contact Envirep at 717-761-7884 or

By Michael Gillespie, President at Envirep