PW Tech Volute Dewatering Press. Represented by Envirep in PA, MD, NJ, DE, VA, WV and DC.

Sludge Dewatering at WWTPs

PW Tech Volute Dewatering Press at a Pennsylvania Wastewater Treatment Facility
PW Tech Volute Dewatering Press at a Pennsylvania Wastewater Treatment Facility

Sludge dewatering plays a pivotal role in wastewater treatment facilities. PW Tech’s Volute Dewatering Press stands out as an innovative solution that surpasses conventional dewatering methods on multiple fronts. Engineered for exceptional dewatering efficiency, long-term cost-effectiveness, and user-friendly operation, it offers a cutting-edge approach.

Here’s how it works: Sludge initially enters a mixing tank, where it thoroughly combines with a polymer. Subsequently, the sludge progresses through a floc tank, where gentle mixing takes place. From there, it flows into the dewatering drum, where the magic happens. The key to this process lies in the unique dewatering drum itself. This drum achieves both sludge thickening and pressing in a single, streamlined operation. Remarkably, it can handle sludge with concentrations as low as 0.1% solids directly from wastewater treatment processes like sequencing batch reactors or oxidation ditches, producing a solid cake with a solids content exceeding 25%.

The Volute Dewatering Press is a screw press, but unlike traditional screw presses, the Volute Dewatering Press features a unique dewatering drum. Spacers and fixed rings are held in place on tie rods. Moving rings, slightly smaller than the outer diameter of the screw and slightly narrower than the spacers, are located between the fixed rings and are moved by the screw. The constant movement of the moving rings cleans the narrow gaps between the moving and fixed rings, preventing clogging. The moving rings also cut into the sludge cake, allowing additional surface area for the release of water.

The initial section of the dewatering drum is the thickening zone, where most of the filtrate is discharged. The pitch of the screw narrows, and the gaps between the rings decrease towards the end plate, where solids are discharged. Pressing of the sludge occurs at the end of the drum just before the end plate.

Operation and Maintenance

The Volute Dewatering Press is fully automated, requiring very little operator attention other than periodic inspection and polymer drum replacement. Depending on operating conditions, a partial overhaul of the dewatering drums may be necessary every five to ten years. This two-hour operation is accomplished in the field with minimal disruption to plant operation.


  • High Cake Solids
  • Low Power Usage
  • Low Installed Cost
  • Low O&M Requirements
  • Small Footprint
  • Fully Automated
  • Reduced Wash Water Consumption
  • Minimal Noise, Low Odors

The enclosed dewatering process operates at speeds of under 10 rpm with minimal wear. The result is high cake solids, excellent filtrate, and minimal or no manpower required. The low power usage by the press and low water usage provide savings year after year.

The entire operation is controlled by the Volute Dewatering Press control panel.

The Volute Press model sizes range from 10 GPM to 300 GPM, with a small footprint, and space for additional drums can be provided for future requirements. The Volute Press is engineered for wastewater treatment plant operators.

Learn more about the PW Tech Volute Dewatering Press

PW Tech offers free pilot testing for qualified customers. Contact Envirep to learn more about the Volute Dewatering Press.

CLICK HERE here to view our manufacturers’ line card.

by Mike Gillespie, Envirep

Envirep is a trusted manufacturer’s representative, dedicated to serving the municipal and industrial water and wastewater sectors across Pennsylvania, New Jersey, Maryland, Delaware, the District of Columbia, and Virginia.

Our mission involves representing esteemed manufacturers of cutting-edge equipment tailored for various wastewater and biosolid handling processes. Furthermore, we proudly advocate for manufacturers of equipment designed for the pumping, treatment, distribution, and storage of clean, potable water.