Manure Covers and Biofilters for Managing Odor and Air Emissions

Covers and biofilters are two techniques that can be used to help manage odors and other airborne emissions from animal feeding operations and manure storage units. Watch these two videos to learn about covers and biofilters, how they work, and related costs and benefits of different methods to reduce airborne emissions. Links to additional techniques and information are given below.

Manure Storage Covers for Reducing Odor Emissions

Visit the Feedlot Air Emissions Treatment Cost Calculator website to download a spreadsheet to help calculate costs and benefits of installing technologies to treat odors and gas emissions from animal feeding operations. A good tool to assess current management practices and their impact on air emissions, including odor, is to use the National Air Quality Site Assessment Tool (NAQSAT). Manure Storage Covers includes many more resources on this topic.

Biofilters for Reducing Odors and Gas Emissions

More is available on Biofilters. There are several methods that can be used to manage odor and other airborne emissions from animal feeding operations. Additional techniques and management information include:

More Videos in This Series

Additional educational materials are available at Air Quality in Animal Agriculture including an archived webinar on “Clearing the Air on Biofilters

Acknowledgements

For more information about this video or these resources, contact Dr. Kevin Janni, University of Minnesota kjanni@umn.edu

These materials were based upon work supported by the by the National Institute of Food and Agriculture, U.S. Department of Agriculture under Agreement No. 2010-85112-20520.

Any opinions, findings, conclusions, or recommendations expressed in this video are those of the speaker and do not reflect the view of the U.S. Department of Agriculture.

Manure Storage Covers Curriculum Materials

Air emissions from animal agriculture operations and their associated manure storage are being examined more closely as a way to mitigate potentially harmful gases. Covers are becoming popular as a way to collect methane (a potent greenhouse gas) for beneficial reuse as a renewable energy source.  The materials on this page were developed to assist educators and professors who include manure storage covers as a topic in their classrooms or educational programs.

Fact Sheets

Rose Stenglein, Charles J. Clanton, David R. Schmidt, Larry D. Jacobson, and Kevin A. Janni, University of Minnesota

Video: Manure Storage Covers for Reducing Odor Emissions

Photo Galleries

Positive Air Pressure Covers

Negative Air Pressure Covers

Technology Summaries

These are from a 2008 conference hosted by Iowa State University

Acknowledgements

These materials were developed by the Air Quality Education in Animal Agriculture (AQEAA) project with with financial support from the National Research Initiative Competitive Grant 2007-55112-17856 from the USDA National Institute of Food and Agriculture. For questions about the materials on this page contact Dr. Kevin Janni, University of Minnesota (kjanni@umn.edu). For questions about the AQEAA project, contact Dr. Rick Stowell, Unviersity of Nebraska (rstowell2@unl.edu). If you have presentations, photos, video, publications, or other instructional materials that could be added to the curricula on this page, please contact Dr. Janni or Jill Heemstra (jheemstra@unl.edu).

Gas Impermeable Film and Sheet for Control of Methane and Odors in Agricultural Applications

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Swine, Dairy, Beef, Poultry
Use Area: Manure Storage, Manure Treatment
Technology Category: Covers
Air Mitigated Pollutants: Odors, Methane, Ammonia

System Summary

For many years, food packaging has incorporated barrier layers to contain odors, flavors, oils and moisture along with the food contents while excluding contamination and oxygen. Until recently, agricultural films and geomembranes were monolithic structures employing only a single polymer or blend. Recent advances in extrusion and lamination equipment allow the incorporation of these barrier layers in large scale agricultural structures and operations such as floating covers over animal waste storage, containment geomembranes for biogas generation, silage storage and fumigation films.

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Co-extruding a thin layer of ethylene vinyl alcohol (EVOH) in a linear low density polyethylene (LLDPE) geomembrane dramatically reduces the permeability to a wide range of gases and volatile organic carbon molecules including: methane, ammonia, carbon dioxide, oxygen, aromatic hydrocarbons, aliphatic hydrocarbons, methyl bromide and most odorous compounds. Methane permeabilites for four geomembranes are given below.

Methane Permeability (cc/(m2*day))
PVC LLDPE HDPE Barrier LLDPE
0.76 mm (30 mils) 1.0 mm (40 mils) 1.0 mm (40 mils) 0.5 mm (20 mils)
900 690 300 <1

Applicability and Mitigating Mechanism

  • Barrier to noxious gases and odors
  • Useful in cover and containment systems

Limitations

  • EVOH is a crystalline polymer and is not elastic. It is flexible but should not be used as part of an elastomeric structure.

Cost

Engineered floating covers with ballasted weight systems, gas extraction systems and rainwater removal systems costs vary greatly. For waste lagoon of about 1/2 acre in size, the cover system can cost from $150,000 to $200,000. Addition of the barrier layer to the geomembrane adds less than $5,000.

Authors

Gary Kolbasuk, Raven Industries, Engineered Films Division
Point of Contact:
Gary.Kolbasuk@Ravenind.com

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

Negative Air Pressure Cover for Preventing Odor Emission from Earthen Manure Storage

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Swine
Use Area: Manure Storage
Technology Category: Covers
Air Mitigated Pollutants: Odors

System Summary

An impermeable synthetic cover system was developed by DGH Engineering in Manitoba, Canada for mitigating odor emission from earthen manure storage basins (EMSB). The system uses lightweight plastic as the cover so that it is affordable to producers. An air pumping system creates negative pressure between the cover and the manure surface to hold down the cover to ensure the cover is robust enough to withstand wind forces. The air pumping system consists of small exhaust fans (four to six fans of 50 – 70 L/s each) and perforated ducts placed about the EMSB perimeter. Odor emission from the NAP covered EMSB (due to the air pumping system) is negligible (1%) in comparison with the open EMSB. Additional benefits of the NAP cover system include the retention of manure nitrogen, thus increasing the fertilizer value of manure; isolating precipitation from the manure, thereby increasing storage volume; and reducing greenhouse gas (methane) emissions.

 

Applicability and Mitigating Mechanism

  • Large surface areas of earthen manure storage basins emit large amount of odor to the atmosphere
  • A NAP cover forms a physical barrier between the manure surface and the atmosphere to prevent odor release into the atmosphere
  • The negative pressure between the cover and the manure surface holds the cover down to resist wind forces.

 

Limitations

  • When using traditional agitation and pump-out equipment, removing and replacing the cover for pump-out may increase the wear on the cover and add labor and time to the pump-out operation.
  • An air assisted agitation system should be used.

 

Cost

The capital cost varies from $10.00 to $15.00 per m², installed. The annual cost per pig marketed for typical 5,000 and 10,000 head swine finisher operations is estimated to be $1.40 and $1.13.

Authors

Q. Zhang1, D. Small 2
1University of Manitoba, 2 DGH Engineering
Point of Contact:
Doug Small, dgh@dghengineering.com

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

A Review of Permeable Cover Options for Manure Storage

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Beef, Dairy, Swine
Use Area: Manure Treatment
Technology Category: Covers
Air Mitigated Pollutants: Ammonia, Odors, Hydrogen Sulfide

System Summary

Covers have been demonstrated to provide effective odor and air emissions control for manure storage structures. Impermeable covers made from flexible synthetic materials provide excellent odor and emissions control, but typically have a high capital cost requirement. Permeable covers provide an alternative to impermeable synthetic covers. Permeable covers will typically not provide as great a level of odor control as impermeable covers, but the initial capital cost is lower. Permeable covers do not require gas or rain water collection systems since gases are allowed to migrate through the cover and rainwater will infiltrate through the cover into the storage. Permeable covers have been successfully constructed from a variety of materials including straw, light weight expanded clay aggregate (LECA), ground rubber and geotextile materials. Materials such as straw, have a short lifespan (from two to six months depending on manure solids content and rainfall levels), while materials such as LECA have been shown to remain viable for more than ten years. Various permeable cover materials have been shown to reduce odor from 40% – 90%, and to reduce ammonia from 40% to 80% depending on permeable cover material and depth.

 

Applicability and Mitigating Mechanism

  • Permeable covers provide a layer on the manure surface that shields the manure surface from contact with the air
  • Most permeable cover materials provide an aerobic zone in the cover material that will help control odor
  • No gas or water collection systems are required since both gases and rain water will pass through the permeable cover material
  • Some permeable cover materials such as straw provide a short-term solution, while other like LECA can last more than ten years

 

Limitations

  • Some permeable cover materials (such as straw) have very short effective lives (2 – 6 months)
  • Long-term permeable cover materials (such as LECA) can have costs near those of synthetic impermeable covers
  • If a permeable cover material sinks into the stored manure, it must be dealt with during land application
  • Rainwater volume must be accounted for in the manure storage since direct precipitation will infiltrate into the manure storage

A permeable straw cover on an earthen manure storage structure.

Cost

Permeable covers can provide reductions in odor, ammonia and hydrogen sulfide emissions from manure storage facilities. A wide variety of organic and manmade materials have been utilized to construct permeable covers with variable results and costs ranging from $0.10 to $1.75 per square foot installed. Straw is the least cost permeable cover material with an approximate cost of $0.10 per square foot installed. Longer lasting materials such as LECA have installed costs that can exceed $1.00 per square foot installed. Permeable cover materials are typically floated on the stored manure surface and can provide an aerobic zone that manure gases must pass through when released. Permeable covers can be used with earthen, concrete and steel manure storage systems and with slurry manures generated by swine, dairy and beef animals.

Lightweight expanded clay aggregate (LECA) cover on a concrete swine manure storage tank.

Authors

Robert Burns and Lara Moody, Iowa State University
Point of Contact:
Robert Burns, rburns@iastate.edu

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.

Manure Storage Covers for Mitigating Air Emissions from Animal Agriculture

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

 

Manure Storage Covers for Air Emission Mitigation

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.