Brenneman, Greg

Karsten, Arlin W.

Steinhart, Terry L.

English

Steinhart, Terry

Karsten, Arlin

Digital Repository @ Iowa State University (ISU)

Iowa State University Management/EconomicsBio-filter effectiveness on Ten-Stall Farrowing Building PitExhaust a Demonstration ProjectTerry L. Steinhart, ISU Field Specialist/Swine,Dr. Greg Brennenman, ISU FieldSpecialist/Agriculture Engineer, Arlin W.Karsten, D.V.M. Assistant Professor AgriculturalSciences Kirkwood Swine Education CenterASL-R1785Summary and ImplicationsA demonstration project at the Kirkwood SwineFacility at Kirkwood Community College in Cedar Rapidsis pleasing to both smell and sight. A biofilter was designedfor the exhaust system at the college's 10-stall farrowinghouse to decrease odors and blend in visually with thesurroundings. The biofilter was successful in reducing thepit fan odor to a smell of fresh turned soil. The biofilterdesign was acceptable to the college and facility manager.IntroductionThe idea of using a biofilter is to cut down or eliminatethe odor from the pit exhaust fans. The pit fan from thisfarrowing house blows directly to doors from the showerand personal changing room for the facility. Because of thehog facility on campus and site location, the bio-filterneeded to blend in with its surroundings. The objective ofthis project is to demonstrate the effectiveness of a bio-filteron farrowing room exhaust. “Odors from livestock facilities are an issue for manycommunities and livestock producers. Odor sources forlivestock production systems include buildings, manurestorage, and land application of manure. Most complaintshave focused on emissions from outside manure storages.Therefore, the current trend in swine production is to usedeep pit manure storage beneath the slatted floor in thelivestock building that then becomes the major odor source.Biofiltration is an odor reduction technique that can beadapted to reduce emissions from these mechanicallyventilated facilities” (1).After consultation with Richard Nicolai of theUniversity of Minnesota’s Biosystems and AgriculturalEngineering Department his recommendations were usedwhen designing this biofilter. The recommendations areavailable in a document called Biofilter Design Informationat http://www.bae.umn.edu/extens/aeu/baeu18.html.Results and DiscussionBuilding the biofilter wasn’t a difficult process and thecost is relatively low when comparing other odor reducingtechniques. It took three people a total of five hours toconstruct the biofilter. This demonstration project is a bitmore costly because we chose to build a “box” to containthe biofilter material for its visible on-campus location.Picture 1: Base of biofilter being constructed.In picture 1, the Kirkwood biofilter base is made of aplywood floor and 2x6 boards on end. In picture 2, the 2x6boards are covered with quarter-inch mesh wire. The fanhousing and biofilter plenum is being attached. The buildingpit air is forced into the space below the mesh and throughthe biofilter material between the 2x6 boards. The wiremesh keeps the wood chips and compost material fromfalling into the area where the exhaust air enters thebiofilter. In picture 3, the seams are caulked and a 12-inchstrip of landscape plastic (6 inches up the side and 6 incheson top of the mesh wire) is placed around the bottom of thebox. This is to keep the air from “escaping” up the side. Theplastic forces the air away from the edge and into the filter.The plenum acts like a chimney to push the air through thefilter material. Current biofilter material includes woodchips, composted horse manure, woodchips, and cornstalks.The mixture will vary according to what is available andhow much moisture is contained within the material itself.Results and DiscussionOn a farm design, there wouldn’t necessarily be a needfor sides. Pallets could be used and covered with _” meshwire. A plenum could be constructed of plywood todistribute the air under the pallets and up through thecompost material. For best results about 75% compost and25% wood chips should be available at little or no cost. Picture 4 shows the filter being loaded with a mixtureof 75% compost and 25% wood chips. The reason for thewood chips is to prevent compaction of the compost.  TheBiofiltration process involves bacteria and fungi that live onthe media surface. “As the exhaust air passes by this biofilmon the media, the bacteria eat or oxidize the odorous gasses.Therefore, a biofilter is not like a dust filter, which fills upand must be cleaned; instead, it is a living ecosystem ofmicroorganisms that continually feed on odorous gases. Tosupport this living ecosystem, a biofilter needs the correctmoisture content, oxygen level, temperature, and foodsource to stay alive” (2). This design requires about 1 inchof water sprinkled over the top per week. Learning howmuch moisture the biofilter requires is more experience thanknowledge. The filter needs to stay moist, but over-wateringcauses the compost to compact. Compaction will not allowenough airflow through the biofilter. Cornstalks were addedwhen the filter was over-watered, compaction occurred andairflow was severely restricted. Adding the cornstalks andmixing the filter material allowed the biofilter to againfunction properly.Picture 2: Plenum being attached to exhaust fan housing.Brennenman suggest a good rule of thumb is that youneed about one square foot of biofilter material for every 10cubic feet per minute (cfm) of ventilation. Your exhaust fanwill need to operate against a higher static pressure whenyou’re using a biofilter. This means your fan should be ableto provide adequate airflow at least 0.25 inches andpreferably up to 0.5 inch of static pressure. Replacing yourfan with a more powerful one is where the cost comes in fora producer. However the specifications on your fan shouldbe obtained to see if it would be adequate. Fan replacementcost is estimated at $350-400.Picture 3: Plastic inside filter forces air away from sides.Picture 4: 75% compost and 25% wood chips added to thebiofilter.As shown in picture 5, the biofilter continued to workduring the winter. No moisture is added in the winter,because the building generates enough humidity to keep thebiofilter working properly.Picture 5: Snow melted off in winter from exhaust heat.AcknowledgmentsThis demonstration project was funded and supported by theIowa Pork Industry Center. Dr. Arlin Karsten and thestudents in his swine program maintained the biofilter. Aspecial thank you to Sherry Hoyer for her help indeveloping news releases and web site design. The web sitewith more pictures and the biofilter plan is located at:http://www.extension.iastate.edu/ipic/projects/bf/index.htmReferences1. Nicolai, R. E. and K. A. Janni. 1997. Development of aLow Cost Biofilter on Swine Production Facilities.ASAE Paper No. 97-4040. St. Joseph, MI: ASAE.2. Nicolai, R.E. 1998. Biofilter Design InformationBAEU-18, Department of Biosystems and AgriculturalEngineering University of Minnesota.http://www.bae.umn.edu/extens/aeu/baeu18.html

Bio-filter effectiveness on Ten-Stall Farrowing Building Pit Exhaust a Demonstration Project

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Bio-filter effectiveness on Ten-Stall Farrowing Building Pit Exhaust a Demonstration Project

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