CHILTON — DVO Inc. continues garnering headlines with installations of its patented anaerobic digesters throughout the country and around the globe.

But recent accolades and high-profile projects aren’t necessarily the company’s biggest source of pride.

“One of the things we’re most proud of is the fact that the first digester we ever built in 2001 is still running today (at Gordondale Farms in Nelsonville), and there are very few people anywhere who can say that,” said Melissa VanOrnum, vice president of marketing for DVO, which is based in Calumet County.

“Our track record of successful digesters and repeat business at farms that expanded shows we are committed to quality service and being a great partner with our customers. That’s really important to us.”

During the past 18 years, the family-operated company has installed more than 120 of its patented Two-Stage Linear Vortex digesters in 19 states, including 26 sites throughout Wisconsin. The company’s digesters also can be found in Canada, Australia, China, South Korea, Serbia and Chile.

The majority of DVO digesters are installed on dairy farms, including 10 dairies in Fair Oaks, Ind. Poultry, swine and beef cattle farms also are on DVO’s agricultural list.

DVO digesters were developed under the direction of company president Steve Dvorak, who began working with traditional “upright” digesters in 1985. In 1999, he began a 1½-year process working in labs and on farms to perfect a new system. The result: Two-Stage Linear Vortex digesters.

In layman’s terms, DVO digesters use bacteria to first break down complex materials into simple acids like vinegar. Then, methanogens convert those simple acids into carbon dioxide and methane. Hence the first part of the name: Two-Stage.

Linear Vortex refers to material flowing horizontally. The system is then agitated with the injection of biogas, causing a vertical lift. DVO’s patented process then creates a circular mixing, or corkscrew (vortex) effect.

Manure and other organic wastes are converted into three valuable byproducts: a biogas that can be burned in a genset or turbine to create electricity or scrubbed to make natural gas (for example, CNG for transportation fuels); a biosolid, used as high-quality bedding for cows or as a soil amendment; and a liquid stream that is non-odorous and can be applied as a fertilizer to growing crops.

“One of the main reasons places have these digesters is for the bedding for cows,” Dvorak said. “A lot of people use the separated solids after the digester for bedding. It gives them more income by replacing the cost of buying bedding and also then selling the surplus bedding.”

VanOrnum, who is Dvorak’s daughter, said his creation has stood the test of time.

“He worked hard to combine those two traditional types of digesters (upright/mixed digesters and plug flow digesters) into one,” VanOrnum said. “So when people look at our digester they think it’s just a plug flow, because that’s what plug flow digesters look like from the outside. But what they can’t see is that corkscrew mixing, that vortex, inside the digester.

“So he basically took a plug flow digester and added mixing to it. He got the benefits of both without the drawbacks of either one of them. That’s what makes us unique — he combined the two. Nobody else is mixing a plug flow with biogas like this.”

Dvorak said the Two-Stage Linear Vortex digester also accommodates sand-bedded dairies.

Before buying a DVO digester, customers often want to know how much biogas they’ll make, how much they’ll get for bedding, the project’s cost, whether there are any government programs available for cost sharing and how much labor is required.

Dvorak said the simplicity of his digester design means, “Typically every dairy has somebody who’s already handling the manure and bedding for their cows. That person could easily take care of the digester because it only takes half an hour a day to run it.”

Farm digesters usually can be built in about six months. Dvorak said they can be designed to accommodate any size farm; it just depends on the volume of waste.

The largest individual farm with a DVO digester is in Idaho with 16,000 cows, whereas the smallest is in Vermont with 400 cows.

DVO made headlines this winter in California, where the California Public Utilities Commission, California Air Resources Board and California Department of Food and Agriculture announced funding for six pilots projects in the San Joaquin and Sacramento valleys designed to demonstrate the efficient production of biomethane from dairy digesters and its injection into natural gas pipelines.

DVO, in conjunction with JG Weststeyn Dairy (2,200 milking cows) in Willows, Calif., was awarded funding for one of the pilots. Biomethane generated by the digester will eventually be used as vehicle fuel in California, replacing about 1.25 million gallons per year of fossil fuels.

Another significant benefit of the digester, VanOrnum said, is its ability to better handle nutrients.

“A digester doesn’t destroy nutrients,” she said. “The fertilizer value, it’s the same amount of NPK, but what happens inside the digester is the bacteria will convert the fertilizer from an organic to an inorganic form, so it comes out like 85 percent inorganic.

“What that means is now this digested liquid is no longer like raw manure. You can put it right onto a growing crop. So we have our customers applying their digested liquid during growing season. It allows them to play Mother Nature. If it’s the middle of July and we haven’t had rain in three weeks, they can go to their lagoons and put the digested liquid onto their crops.

“It’s 98 percent water, and it doesn’t smell when they’re applying it because we killed the odor at the digester. So it allows them to put nutrients on when the plants need it, so they increase their crop yield. But it also allows them to put a greater volume of liquid onto the land.

“So not only are they increasing their crop yield and reducing their likelihood of runoff and reducing the odor when they spread … but we’ve had customers be able to add cows without purchasing additional land.”

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