WASHINGTON STATE DAIRY finds success with German based innovation.

The George DeRuyter & Sons Dairy is a third-generation dairy farm that began production in 1972.

George DeRuyter and Sons Dairy is located in one of the most active dairying areas in the United States- Central Washington. Outlook, WA has been the home of this family dairy for three generations. Self sustainability has become the focal point of their operation to secure the future of their herd for years to come. In 2006, the DeRuyter & Sons became Central Washington’s first Dairy to build an anaerobic digester to convert manure into biogas.

Each day manure from thousands of DeRuyter’s cattle are pumped into a 3.3 million gallon-capacity tank, known as an anaerobic digester. Up until the past few months this gas was used to produce renewable electricity. Recent additions have allowed DeRuyter’s to clean and compress this gas to be sold as Renewable Natural Gas- “RNG” and be injected directly into the pipeline.

THE PROCESS

Anaerobic digesters operate using a process in which organic materialsbiodegrade without oxygen. Acting like the stomach of a cow, the digester tank facilitates the growth of the same bacteria used by our bovine friends to break down biomass and fodder. As the biological break down occurs, it produces a mixture of methane and carbon dioxide, referred to as biogas. The biogas is then captured to generate electricity.

When the digestion is complete, the remaining byproduct is a nutrient-rich slurry called digestate. This digestate is processed through the Boerger BioSelect RC’s for separation providing the dairy with consistent fiber to be used for direct bedding of cattle or to be composted for later use.

DeRuyter’s current separation process did not provide them with the amount of fiber bedding their dairy required. “It was just time to get something different,” said Gabriel Rivera, who performs maintenance at DeRuyter & Sons. “They wanted to upgrade the roller press they had for quite some time, to get better cow bedding.”

When DeRuyter & Sons was ready to make a change, they spoke with their digester operations group, Regenis. One of the most successful builders and operators of manure digesters in North America, Regenis had experience using the Boerger RC 75 separation technology at a site operated in Idaho. Knowing of DeRuyter’s need to update their current separation system, Regenis extended an invitation to see a Boerger system in action.

THE CHALLENGE

Prior to November 2019, there was no relationship between the George DeRuyter & Sons Dairy and Boerger, however, they did have a mutual relationship with Regenis.

“We were approached by Dan DeRuyter to come in and provide them a separation system that would be more automated and have less maintenance. This would free up some of his operators to do other things,” said Blane Braaten, agriculture & biogas manager for North America. “We downsized their entire separation system footprint. They were using the slope-screen style separators and roller presses. There was a lot of moving parts with those and his maintenance was getting costly.”

THE SOLUTION

“The Regenis company was veryhappy with their Boerger Bioselect. So much so they invited Dan DeRuyter over to take a look at it,” Braaten said. “DeRuyter saw the Bioselect in action and next thing you know, he was calling me saying, ‘Hey, I need one of these.’”

“DeRuyter had other upgrades going on around their digester so it turned out to be a good time to install the Bioselect. The timing felt right so that their operation could start 2020 with a new and up-to-date system.”

Boerger representatives made the trek from Minnesota to the Washington site when the RC 75 order was placed by DeRuyter & Sons. “We brought in the Bioselect RC 75, set it up and quickly got it running,” Braaten said. “We were handling 100 percent of his flow with one press where in the past, he was in operation with two, sometimes three slope screens to handle the flow rates.”

The media to be separated find their way through the inlet opening into the Bioselect. The outer cylinder is separated from the auger by a roundly sealed wire-wound screen pipe. The auger has a frictional connection to the drive. The imported liquid flows into the screen area next to the drive. The liquid flows through the wedge wire screen into the outer vessel area. The liquid drains
through the liquid outlet.

The solid contents remain on the screen surface. They are conveyed into the press channel by the rotating auger. Powerful subsequent dewatering takes place in the press channel. The rotating auger has a Multi Disc (sealing disk), which can be shifted in axial direction, at the non-drive end. The adjusting unit presses the Multi Disc against the auger and the compressed thick matter plug. When the thrust force of the plug is greater than the spring force of the Easy Shift unit, a slot for discharging is created by axial movement. A scraper edge is used to loosen and expel the solids.

“It isn’t like your typical screw press,” Braaten said. “We operate with a counter bearing on the discharge end of our auger. This allows for tight tolerances and keeps alignment on the auger and screens.” It’s physically impossible to have any metal on metal contact.

“Among the highlights of our screw press is that it’s a closed-loop system. The slurry is never open to atmospheric air, so we are coming right out of a digester that is being sent directly to the screw press.

The screw press is non-vented, positive pressure. The liquid never comes into contact with the air until it’s discharged into the lagoon. As far as putting the Bioselect inside a building, we’re not dealing with so much of the gaseous atmosphere.”

THE RESULT

The Bioselect RC 75 replaced the use of two slope screen separators, two conveyors and a large roller press. It currently processes 230 gallons per minute (gpm), reducing run time and providing a better and more consistent bedding solution for the cows.

“The fiber comes out with a lot less moisture than with the roller press,” Rivera said. “It saves me maintenance time. All I’ve got to do is make sure she is running. Braaten remains in communication with Rivera about the product’s operation, and Rivera praised the Boerger team for being available when issues sometimes arise. The next step for the DeRuyter & Sons team is to purchase one more unit and then enclose the separation installation in its own building.

“Due to the condensed footprint, Dan DeRuyter and his team are planning to build a small building around the RC75’s to protect them from the drastic annual temperature fluctuations. This will allow them to operate 24/7, even during the winter when it tends to occasionally freeze.” Braaten said.