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Simple BioFilter Cleans Up Manure Odor
Dick Nicolai's pigs don't smell any sweeter than any other pigs, but you'll never hear a complaint about smells from any of his neighbors. That's because he vents his hog houses and the manure pits under them through a network of pallets covered with a mix of compost and wood chips.
"Since we set up our biofilte
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Simple BioFilter Cleans Up Manure Odor MANURE HANDLING Equipment 28-3-28 Dick Nicolai's pigs don't smell any sweeter than any other pigs, but you'll never hear a complaint about smells from any of his neighbors. That's because he vents his hog houses and the manure pits under them through a network of pallets covered with a mix of compost and wood chips.
"Since we set up our biofilter, neighbors have been constantly monitoring the site as they drive by and say they haven't smelled anything," says Nicolai, who began work on his system in 1997. "It takes out about 90 percent of the odor."
The simple system was not so simple to develop. After 27 years of farming, Nicolai was working on a Ph.D. at the University of Minnesota. At the same time, he was expanding his Hector, Minnesota hog operation.
"The toughest thing was getting the correct air flow and the correct mix of compost and chips," he recalls.
He installed a system of exhaust fans that pull odor down through the slats into the pits beneath the barns and then out laterally through air ducts. Wood pallets form an air plenum that distributes the odor-rich air beneath the chips and compost. Plastic netting with 1/2-in. grids on top of the pallets keeps the material from falling through.
Nicolai used a TMR feed mixer to mix wood chips and compost in a 70:30 to 50:50 ratio. The more chips, the less fan pressure needed to force the air up and through the biofilter. The mixer's side discharge auger was used to cover each row of pallets.
Nicolai recommends 1 sq. ft. of biofilter 1 ft. deep to treat about 10 cfm of air. Cost estimates for materials and labor run from $150 to $250 per 1,000 cfm.
"The major thing to think about is that biofilters are hard to retrofit," warns Nicolai. "Even if you don't want to install one yet, a few changes during construction will let you add one at a later time."
In addition to hay farming, Nicolai is now on staff at South Dakota State University. He is working to refine his biofilter.
"We have started work on a vertical biofilter," he explains. "We want to get down to a smaller footprint, something like an old double corn crib or a cylinder where we blow the air through the center and out the walls."
Contact: FARM SHOW Followup, Dick Nicolai, Agricultural & Biosystems Engineer, P.O. Box 2120, SDSU, Brookings, S. Dak. 57007 (ph 605 688-5663; email: nicolaid@sdstate.edu).
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