Centrifugal Stillage Separation

8 Feathers Distillery explains how Kason Corporation treats their waste stream to eliminate sewage surcharges, decrease solid waste disposal fees, and provides a “free” food source for local livestock to nearby farmers in an article published across the globe in Filtration + Separation, Industrial Water World, Brewer & Distiller International, and other publications. 

Separation Evaluation – Solving for Efficiencies

8 Feathers, founded in 2004, produces a wide variety of spirits using locally-sourced grains and water from a nearby artisanal well. The distillery could not lauter because their hammer mill grinding process produces fine grains that clogged the filter media. In searching for solutions, filter presses, screw presses and chemical flocculation were investigated and ruled out. The Kason CENTRI-SIFTER proved to be the most cost-effective choice that occupied a small footprint, minimized maintenance, and offered simple cleaning options.

8 Feathers provided a 10-gallon (38-litre) sample of stillage for testing which was conducted on both circular vibratory and centrifugal separators. In the footprint desired, the vibratory separator could not produce output that was as dry as the CENTRI-SIFTER, or at nearly as high a rate — the CENTRI-SIFTER accomplished the desired target of 50 GPM (189 l/min) with capacity to spare.

8 Feathers Distillery was encouraged by the test run when the sifter processed a sample of 1500-gallons (5678-litres) and pushed 40 GPM (151 l/min) without performance degradation. 8 Feathers purchased a Kason model MO-SS CENTRI-SIFTER with a 140-mesh (105 micron) heavy-duty reinforced stainless steel screen to provide effective separation and minimize the risk of screen blinding.

Processing over 3,000 pounds of grain a week while distilling, 8 Feathers produced more than 7,500 pounds of stillage waste as a byproduct. Discharge to the municipal wastewater treatment system requires liquid which is free of solids and within an acceptable pH range to avoid increased sewage surcharges.

To minimize waste disposal costs, 8 Feathers needed a solution that would allow them to successfully separate spent grain from the liquid without contaminating solids while neutralizing the liquid waste discharged.

Installing the Sifter

Once installed, 8 Feathers was able to sustainably and economically dispose of its grain slurry waste by separating the grain from water using a centrifugal sifter and could donate grain to local farmers as livestock feed. The aggressive screening action of the CENTRI-SIFTER removes liquids to minimize both sewer surcharges and transportation costs associated with the waste while providing a “free” food source to local farmers.

The CENTRI-SIFTER was Installed 8.5 feet (2.6 meters) above the plant floor, directly over the vat that receives the water. The unit measures 21 inches (533 millimeters) wide, 33 inches (832 millimeters) tall and 75 inches (1899 millimeters) long, including its 3 hp (2.2 kW) motor.

The Separation Process

• The liquid/grain mixture is fed into the centrifugal sifter

• The liquid is acidic and

  therefore must have a pH level closer to water

• The watery/grain mixture passes into the horizontal screen cylinder. Auger and rotating paddles propel the mixture against the screen, this accelerates the passage of liquid through the screen

• The liquid then passes through a vat and is treated with ash to reduce the pH level before flowing into the public water system

• Grain solids unable to pass through screen are funneled into a tote

The centrifugal sifter’s end cover plate can be easily hinged open, allowing tool-free removal of the screen cylinder and paddle assembly from the cantilevered shaft for cleaning. The operators simply backwash the sifter with water, cleaning the pipes and the screens at the same time. This cleaning process only took 8 Feathers two or three minutes.

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