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

Sludge Dewatering for WWTP Operators

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

Sludge Dewatering for WWTP operators is essential to operate a wastewater treatment facility. PW Tech’s Volute Dewatering Press is an innovative sludge dewatering product that offers many advantages over traditional dewatering technologies. It is designed for superior dewatering performance, long-term value, and ease of operation. Sludge is fed into a mixing tank, where the polymer is thoroughly mixed with the sludge. The sludge then passes through a floc tank where gentle mixing occurs. From there, the sludge overflows into the dewatering drum and is pressed. The key to the process is the unique dewatering drum. The drum can achieve thickening and pressing of the sludge in a single, compact operation. It can take sludge as dilute as 0.1% solids directly from the wastewater treatment process, such as a sequencing batch reactor or oxidation ditch, and produce a cake of over 25% solids.

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
  • Low Wash Water Use
  • Low Noise, Low Odor

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 over 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 manufacturer’s representative serving the municipal and industrial water and wastewater market in Pennsylvania, New Jersey, Maryland, Delaware, the District of Columbia, and Virginia.

We represent manufacturers of equipment used to pump, treat and dispose of wastewater and biosolids. We also represent manufacturers of equipment used to pump, treat, distribute and store potable water.