PWTech – Volute Dewatering Press

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PWTech – Volute Dewatering Press

About the Company:

Process Wastewater Technologies LLC was formed in December, 2006 as the residual manufacturer of wastewater and combined sewer overflow (CSO) products when the parent company in the U.S., CDS Technologies, Inc. was sold to CONTECH Construction Products Inc.

PWTech has a rich heritage in the storm water, waste water, CSO, and SSO treatment industry. Their success is based on a high-rate screening technology known as continuous deflective separation (CDS). Developed during the early 1990s, continuous deflective separation rapidly became the number one technology across the country for storm water treatment, and then was adapted to be utilized in the treatment of CSOs as well.

While the CDS Technologies name and the storm water treatment portion of the business was sold in 2006, Process Wastewater Technologies continues to be a leading manufacturer of products for the wastewater and CSO treatment industry. With over $50 million in projects at its start-up, PWTech continues to grow and develop its wastewater and CSO/SSO treatment and sludge thickening and dewatering technologies.

About the Solution:

This innovative sludge dewatering product offers many advantages over conventional sludge management methods. Originally developed in Japan, the Volute Dewatering Press is patented worldwide, with more than 650 installations. The key to the process is the unique dewatering drum design. This drum is able to achieve both thickening and pressing (dewatering) of the sludge in a single, compact operation. It can take sludge as dilute as 0.1% solids, directly from a biological process, such as an oxidation ditch, and produce a cake of over 25% solids.


The PWTech® Volute Dewatering Press has been installed to handle a wide range of sludges. It is especially useful when sludges have a high oil and fat content that would bind filter materials. Types of sludge the Dewatering Press has been utilized to dewater:

  • Waste biological sludges (including WAS, fixed film, MBR, aerobic and anaerobic digested)
  • Potable water sludges (including alum, ferric, and PAC sludges)
  • DAF float from slaughter houses and other agricultural processes
  • Oil sludge from machining operations
  • Wastes from textile processingFood processing and wash-down wastes

  • Highly efficient dewatering
  • Eliminate thickening and storage tanks
  • 24-hour unattended operation
  • Reduced running costs
  • Can handle feed sludges from <0.2% to >4%
  • Less noise, less odor
  • Low power and wash water consumption
  • Rapid installation
A Fully Automated System

The Volute Dewatering Press is a fully automated system capable of starting up, operating, and shutting down with no operator intervention. This is possible because the control panel is designed to control the operation of wasting sludge directly from the biological processor or clarifier, the automated polymer feed system, flocculation, dewatering, and any conveyors required to remove dewatered cake. Thus, all components of the dewatering system work together, automatically starting up, operating, and shutting down as required.

Design Criteria

PWTech can provide complete systems or work with other suppliers to provide an integrated package. In addition, unit operating and alarm outputs for connection to plant PLC/SCADA systems are standard. Several models are available.

PWTech 9004 Yellow Brick Road, Suite D Rosedale, MD USA 410-238-7977 Visit Company Website

Solution Type

  • Chemical Flocculation


  • Equipment Vendor


  • Concentrated Nutrients


  • GHG
  • Nitrogen
  • Odor
  • Phosphorous
  • Storage

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Solution Strengths, Weaknesses and Critical Indicators

Chemical flocculation technologies remove the non-dissolved particles from the waste stream typically resulting in irrigation quality “tea water”:

  • Produces a clay like cake which is high in phosphorus and with significant amounts of organic nitrogen.
  • Supported technologies include belt presses, centrifuges, dissolved air flotation systems and others; all requiring flocculants to achieve high rates of solids removal
  • There is significant variation of chemical and energy use depending on site and by technology
  • There is significant variation of operational intensity depending on site and by technology
  • There is significant variation of cost depending on site and by technology
  • Proven technology for nitrogen recovery, phosphorous recovery, storage reduction, GHG reduction, and odor control

Newtrient Comments/Opinions:

PWTech has not been evaluated using Newtrient's 9-point scoring process because, although their process appears to be suited for use on dairy manure, Newtrient is not aware of any current dairy based projects.

Newtrient will continue to work with PWTech to further refine the cost and performance information as more information becomes available and as new commercial dairy installations come on line.

Newtrient 9-Point Scoring Rating

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