Around 200 people gathered together for the Midwest Manure Summit held in Green Bay, Wisconsin, last month. Fresh off a Superbowl win, Packer fans were eager to get a glimpse of the Lombardi Trophy as they convened for this bi-annual event at Lambeau Field. Just as noteworthy was the wide array of topics to be covered, from air quality and application to renewable energy and runoff. or scroll down to view Bob Nagel, D.V.M. of Holsum Dairy discussing lessons learned from operating a plug-flow anaerobic digester.
John Ferguson, vice president at Conestoga-Rovers & Associates, started the event by discussing air quality regulations coming in 2011.
On a national level, everyone is waiting for the results of the National Air Emissions Monitoring Study (NAEMS) that was undertaken to address the lack of data available to estimate emissions from agricultural sources.
While the research period is complete, researchers are still working the data. Once the final report is published the EPA will begin its public review process as it develops new emission factors.
Building and using biofilters was the topic reviewed by Dr. Joseph Taraba, an extension professor at the University of Kentucky. He discussed the single-stage vertical and horizontal biofilters at work in the U.S., stating designs must maintain low pressure drop; provide sufficient void space in the media bed; be aware of the type, composition and size of the media; consider air treatment volume; and control moisture.
Research Engineer Dr. Marie-Line Daumer from Cemagref, France, shared a European perspective on recycling phosphorus. In certain areas of the continent, phosphorus is a limited resource, in other areas it is in so much abundance it is contributing to surface water eutrophication – impacting wildlife, fish farming, drinkable water sources and leisure use of waterways.
The problem stems from the fact that the phosphorus is generated in heavy livestock areas; however those areas are not the ones in need of phosphorus. In France, dairy farms typically have enough land to spread out their phosphorus levels.
Poultry and swine farms do not have enough land and have a high surplus of phosphorus at the farm level. Those industries have developed ways to dry or separate the manure to allow it to be exported to other areas for land application. She mentioned other biological treatment systems are being developed, but at this point they are not economic at the farm level.
Could sewage treatment plants serve as an emergency option for manure management? Chris Stempa, pretreatment and biosolids manager from the Appleton, Wisconsin, wastewater treatment plant, addressed members of a breakout session on this topic. He said a treatment plant could be an option in this scenario, yet it would be dependent on a number of site-specific factors.
Becky Larson, assistant professor of biological systems engineering at the University of Wisconsin – Madison, highlighted innovative practices used to research the treatment of dairy wash water from her previous work at Michigan State University (MSU).
An aerobic unit built at the MSU dairy farm consisted of settling tanks, treatment units, recirculation and disinfection. A second system was located at a 200-cow dairy and consisted of a 200-foot long bark bed that was 5 feet high.
The third system was a low-cost wetland system that had three cells – two aerobic cells and one anaerobic cell. This was built at a 50-cow dairy. She concluded that all treatment systems were capable of increasing wash water quality and reducing environmental risks, but each one needed further research.
The first day wrapped up with a presentation by Dr. Ariel Szogi of the USDA-ARS. He shared information on technologies developed to recover phosphorus from both liquid swine manure and poultry litter that were alternatives to land application.
Day two began with Dr. Joseph Harrison, professor and nutrient management specialist at Washington State University. He outlined that manure can be a valuable source of nutrients for cropland, but also a source of pathogen, which could raise bio-security and human health concerns.
Some best management practices exist, including anaerobic digestion and land application, to minimize the impact of manure management on the environment. However, as manure is moved off-farm for human crop production, greater attention needs to be given to maintain a low risk of contaminating food crops.
Bedding and co-feeding of non-farm substrates are two important factors impacting the economic sustainability of anaerobic digesters on dairy farms.
Dr. Dana Kirk, manager of the Anaerobic Digester Research and Education Center at MSU reviewed how various forms of bedding can impact digester performance and the resulting biogas production. Co-feeding can increase biogas production and add revenue through tipping fees, however it can come with additional costs as well.
He recommended sampling co-feed products as they enter the digester and keep good records of digester performance. This can increase management and labor. He also said to be sure to stay within the parameters of the digester’s permit.
Dr. Ann Wilkie and her students at the University of Florida have been researching the potential for value-added products from anaerobic digesters, specifically growing algae from the effluent. The algae produce lipids than can be used as a fuel. It could also be used for animal feed or a feedstock for the digester to increase gas production.
Wilkie also addressed ecological issues facing farms of the future. These ranged from climate change to matching manure nutrients to crop needs. They also included the potential growth of biogas and biodiesel production.
Digester technologies are typically geared towards large dairies. Charles Gould, MSU Extension educator, considered the feasibility of digesters for 125-cow dairies. These smaller dairies represent an untapped market; however it’s going to take a combination of solutions from policy to design to make digesters affordable at this size.
The event concluded with Bob Nagel, D.V.M., dairy manager of Holsum Dairy, reflecting on what he’s learned from operating a digester at this Chilton, Wisconsin, farm for the last 10 years. below to find out three things the dairy did right and three things it would do differently in setting up its plug-flow anaerobic digester. PD
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Karen Lee
- Progressive Dairyman Midwest Editor
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