Shafted and Shaftless Screw Conveyors for Handling Residuals Amherstburg WWTP in Ontario, Canada

End User or Owner

Town of Amherstburg
Amherstburg, Ontario

Consulting Engineer

CH2M Hill Canada Ltd
Toronto, Ontario

Contractor

FACCA Inc.
Ruscom, Ontario

Plant Name and Location

Amherstburg WWTP
Amherstburg, Ontario

General Description

The Amherstburg Public Works Department in Ontario, Canada is responsible for the maintenance of the Town’s sewage collection systems working in cooperation with the Ontario Clean Water Agency (OCWA). OCWA operates the sewage treatment facilities. There are six treatment facilities within the Amherstburg town limits. They are the Amherstburg Wastewater Treatment Plant, the Big Creek Treatment Plant, the McLeod Sewage Treatment Plant, the Boblo RBC, Edgewater Lagoons and McGregor Lagoons.

A 2005 study showed the Amherstburg WWTP was reaching capacity and when there were combined sewers and storms, Amherstburg was sometimes sending sewage to the Detroit River. The plant took more than three years to improve and can now serve Amherstburg for the next 25 to 30 years.

KWS Environmental was involved with a project that included modifications and additions to the existing water reclamation facility’s primary and secondary treatment facilities including grit, screenings and biosolids residuals processing improvements. Residuals from grit classifiers, screens and centrifuges were transferred to disposal using KWS Environmental shaftless and shafted screw conveyors.

Design Parameters

Type of Residual: Dewatered Sludge/Biosolids
Material density: 63 to 70 Lbs. per Cubic Foot
Solids, percent by weight: 25-percent
Capacity (max): 3.5 Tons per Hour
Capacity: 120 Cubic Feet per Hour
Duty: 24 Hours per Day, 7 Days per Week

Type of Residual: Grit and Screenings
Material density: 50 to 110 Lbs. per Cubic Foot
Solids, percent by weight: 30-percent
Capacity (max): 1.5 Tons per Hour
Capacity: 60 Cubic Feet per Hour
Duty: 24 Hours per Day, 7 Days per Week

KWS Advantages

KWS Environmental designed and manufactured both shaftless and shafted screw conveyors for all types of residuals at the Amherstburg WWTP. The best conveying technology was chosen for each application. KWS Environmental has experience with many different types of mechanical conveyors and has the ability to design and manufacture the most appropriate conveyor and features for each unique application.

The KWS Environmental shaftless screw conveyors at the bottom of grit tanks required precise design and tolerances to support the need for a watertight conveyor while being submerged under a water head load.

KWS supported the installation, commissioning and training by providing a qualified and registered engineer familiar with the project, design requirements and equipment delivered.

Special Features

The shaftless screw conveyors at the bottom of the grit tanks required the drive shaft to penetrate the grit tank wall and for the shaft seal to be completely watertight while under pressure with a head load in the grit tank. KWS Environmental used a split mechanical seal to ensure that this requirement was met. The split seal allowed removal for maintenance without disrupting the drive or drive shaft.

KWS Environmental utilized shafted screw conveyors with the exclusive Tor-Ri-Flex bearing in an area of limited access for maintenance. It was not possible to use a shaftless screw conveyor because access from above to change liners that would be required was not available. Shafted screw conveyors were the best option given the maintenance access limitations. The KWS Tor-Ri-Flex bearing assembly eliminated any major maintenance on the conveyors, except routine lubrication. Routine lubrication is achieved automatically using spring-actuated lubrication pots which can be replaced without tools. Should major maintenance be required, the bearing assembly can be removed without interrupting the adjacent screw sections.