Skip to main content


Buy Article:

$9.50 plus tax (Refund Policy)

Or sign up for a free trial

In the mid-1990s, the Metropolitan Council Environmental Services (MCES) determined that improved raw sludge dewatering with new high-solids centrifuges could initiate significant changes to the solids processing system at the 250-mgd Metropolitan Wastewater Treatment Plant (Metro Plant), which is located in St. Paul, Minnesota. However, at that time, Metro Plant operations and maintenance personnel expressed skepticism about raw sludge dewatering performance, processing costs, and labor implications of the associated phase-out of the existing thermal conditioning treatment system. In response to these challenges and to prove performance and long-term costeffectiveness, a full-scale centrifuge dewatering demonstration program was implemented. This technical paper presents the findings and the associated changes now occurring at the Metro Plant, that have resulted from the success of the centrifuge demonstration program.

Representatives from MCES operations/maintenance/engineering/construction management and its consultant collaborated for several years to resolve significant issues. This effort provided the framework for procurement, installation, and evaluation of the equipment. The investment in project planning provided a smooth start-up and quick resolution to process problems during the demonstration.

Side-by-side testing was conducted on two full-scale sludge dewatering centrifuges for twelve months. Raw sludge feeding encompassed a large variety of sludge blends, including septic sludge conditions, to define performance variation. The test program also evaluated polymer usage, power requirements, auxiliary and control systems, operations and maintenance cost, and labor requirements of the centrifuge system.

Demonstration results were better than expected. The centrifuges consistently produced sludge cake of 30 to 32 percent solids with a polymer dose of only 5 to 7 active pounds per dry ton of feed sludge. Centrifuge cake burned efficiently in the existing multiple hearth incinerators and required less fuel (compared to heat-treated, roll press-dewatered cake).

With success of the demonstration program, MCES is now proceeding with major system changes at the Metro Plant. These changes include the implementation of a full-scale raw sludge centrifuge dewatering system and the eventual phase-out of the existing thermal conditioning and roll press dewatering systems. The increased efficiencies improved MCES' competitive position while fostering buy-in from Metro Plant staff.
No Reference information available - sign in for access.
No Citation information available - sign in for access.
No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 2001-01-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more