KWS Manufacturing

Inclined Shaftless Screw Conveyor for Transferring Biosolids at Devens WWTF Devens, MA

Download PDF Brochure
End User or Owner

The City of Devens, MA


Nickerson General Contractors
Torrington, CT

Plant Name and Location

Devens WWTF
Shirley, MA

General Description

The city of Devens is located in north central Massachusetts, approximately thirty-five miles northwest of Boston and twenty miles northeast of Worcester. An active military base until 1996, the former Fort Devens Main and North Posts occupy 4,400 acres in the towns of Ayer, Harvard and Shirley. The 2006 Devens Reuse Plan provided a vision and plan for future development of the Devens Regional Enterprise Zone as the Town of Devens and four parcels which revert to the Towns of Shirley, Ayer and Harvard. Development of the municipal services including wastewater treatment was part of the redevelopment plan.

In 2006, the Devens Wastewater Treatment Facility (WWTF) planned an upgrade to their dewatering facility. The upgrade included a new Belt Filter Press (BFP) and a screw conveyor to transfer dewatered biosolids from the BFP to the loading area. The problem was that space was very limited and the city did not want to elevate the BFP for reasons of access for maintenance and to monitor operation.

KWS Environmental provided a solution that required a steeply inclined shaftless screw conveyor from the BFP discharge to the loading area. The combination of a gravity feed transfer from the BFP and a steeply inclined shaftless screw conveyor required a partner who could optimize the design for the difficult requirements. KWS Environmental was excited by the opportunity to push industry conventions and delivered a robust and reliable solution that met the Customer’s unique needs.

Design Parameters

  1. Type of Sludge: Municipal Dewatered Biosolids/Sludge
  2. Material Density – max: 60-70 lbs. per Cubic Foot
  3. Solids, percent by weight: 16 to 23-percent
  4. Capacity (max): 4.0 Wet Tons per Hour
  5. Capacity (max): 150 Cubic Feet per Hour
  6. Duty: 24 Hours per Day, 7 Days per Week
Devens WWTF

KWS Advantages

KWS Environmental designed the shaftless screw conveyor to meet the specific space constraints associated with the dewatering building design. In particular, KWS coordinated the design so that the shaftless screw conveyor could be suspended from the ceiling in the loading bay while optimizing biosolids distribution in the dumpster utilizing the fewest possible slide gates.

Devens WWTF

Special Features

The inclined shaftless screw conveyor inlet was designed with sufficient size and capacity to allow for a head of biosolids to flood the inlet area. The head of biosolids was required to ensure transportation of biosolids up the steep incline. The shaftless spiral was designed with a shorter pitch and wider cross-section to increase conveying efficiency and limit material fall back which can be an issue with steeply inclined shaftless conveyors. All KWS shaftless screw conveyors are designed and manufactured to be very robust, reliable and suitable for the unique environment and operating conditions associated with a wastewater treatment plant. In particular, KWS Environmental utilized the KWS-350 high strength micro alloy spiral. The inclined shaftless screw conveyor was designed to operate at optimal speed to ensure a long, trouble-free life.


"The KWS Environmental equipment fit up, started and ran without issue. Thank you for your expertise in solving this problem."

Daniel B. Radacsi, Project Manager – C. H. Nickerson

Devens WWTF Devens WWTF
Biosolids / Sludge

Get Connected

CEMA Standard Components and Complete Engineered Systems

Contact Us Online Resources