KWS Manufacturing

Biosolids Load Out System for Big Ox Energy Dakota City, NE

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End User or Owner

Big Ox Energy
Dakota City, NE

System Supplier

Centrisys Corporation
Kenosha, WI

General Description

Centrisys is an Original Equipment Manufacturer (OEM) and system supplier of decanter centrifuge systems located in Kenosha, Wisconsin. Founded in 1978, Centrysis provides leading edge technology in decanter centrifuge design by continually improving performance while reducing energy consumption. Centrisys provides dewatering equipment and technology to many industries including wastewater treatment, oil & gas, mining and industrial manufacturing. Centrisys and KWS have had a long, successful partnership in providing solutions for many difficult applications. Since both Centrisys and KWS are ISO 9001 certified companies, equipment and service quality are the best in their respective industries.

Centrisys provided an engineered dewatering load out system for Big Ox Energy in Dakota City, NE. Big Ox Energy converts industrial food and agricultural waste into clean-burning, pipeline-grade, renewable natural gas, known as “green gas.” Good for the economy, the environment, and the industries it supports, “green gas” is a renewable, domestic energy source. At the Dakota City plant, Big Ox Energy converts waste from Beef Products, Tyson Foods and other producers into natural gas.

KWS provided a complete shaftless screw conveyor load out system for the Big Ox Energy project. The KWS load out system was designed to efficiently and reliably convey de-watered biosolids from centrifuges to loadout trailers. The load out system had several design issues to overcome. There were existing structures in the path of the load out system, multiple space constraints within the building causing steep angles for the incline for the shaftless screw conveyors and a roll up door installed in the loadout bay that was affecting truck load out. Engineers from Centriys and KWS worked closely together and coordinated efforts to solve the design issues and provide a successful load out system.

Design Parameters

  1. Product Type: Anaerobically Digested Sludge (Manure / Paunch)
  2. Material Density: 55 to 65 Lbs. per Cubic Foot
  3. Percentage of Solids: 23-percent Solids
  4. System Capacity: 1,090 Cubic Feet per Hour (60,000 Lbs. per Hour)
  5. Duty: 7 Days per Week, 24 Hours per Day

KWS Advantages

Biosolids Load Out System for Big Ox Energy in Dakota City, NE - KWS

Two Centrisys centrifuges were required to meet the processing requirements for the Big Ox Energy project. Engineers from Centrisys and KWS traded 3D CAD models of centrifuges and shaftless screw conveyors and worked together to create the load out system. KWS shaftless screw conveyors are ideal for handling sticky and sluggish materials such as dewatered manure. Shaftless spirals are supported by UHMW trough liners and the bulk material is conveyed without the need for hanger bearings.

Multiple conference calls and meetings resolved any layout issues. The use of Autodesk Inventor 3D Solid Modeling by both Centrisys and KWS made the design of the load out system much easier. KWS was able to determine the exact angle of incline, elevations and spans to meet the requirements to properly load trailers. Upon final layout review, we discovered that the roll up door was directly in the path of the last conveyor drive unit. The conveyor had to clear the roll up door in order for trailers to be loaded. A few design modifications were made and the design was complete.

Special Features

The existing space constraints required KWS to maximize every inch of available space. The Centrifuge Discharge Conveyor located underneath the centrifuges utilized a newly developed low-profile side inlet for ease of alignment and installation. This conveyor discharged directly into the side of the Inclined Screw Conveyor, eliminating any transition between the two conveyors. The Inclined Screw Conveyor then discharged to the Lateral Transfer Conveyor. The Lateral Transfer Conveyor was located on a 5-degree incline in order for the Load Out Conveyor to meet the minimum vertical clearance requirements for loading the dewatered manure into trailers. Ceiling supports with anti-sway lateral supports were used to stabilize the final two conveyors. The Load Out Conveyor had four discharges with three pneumatically controlled stainless steel slide gates with one open discharge at the end of the conveyor to evenly load the disposal trailers.


"The conveyors are working as intended. All of the KWS shaftless screw conveyors fit together and were installed with no problems. We enjoy working with KWS!."

Donald Stade, Lead Mechanical Engineer – Centrisys Corporation

Biosolids Load Out System for Big Ox Energy in Dakota City, NE - KWS Biosolids Load Out System for Big Ox Energy in Dakota City, NE - KWS
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