CONTACT:
John Garnett, Engineered Storage Products Company, Inc., jgarnett@cstindustries.com, 913-748-4559; or,
Jon Anderson, OPEN ROADS, janderson@openroads-bgdn.com, 414-227-1000, Ext. 4
TURN MANURE INTO ENERGY
DES MOINES, Iowa (June 8, 2006) – As livestock producers seek safer and more efficient, sustainable ways to deal with manure, anaerobic digestion might be the answer.
The University of Florida Dairy Research Unit in Hague operates an anaerobic digester, treating manure and turning it into methane gas. “This system is environmentally friendly,” said Dr. Ann Wilkie, an associate professor with the University’s Institute of Food and Agricultural Sciences. “It handles manure and gives back renewable energy.
“The increase in production and concentration of intensive livestock operations, along with increased urbanization of rural regions, have resulted in greater awareness and concern for the proper storage, treatment and utilization of livestock manure,” said Dr. Wilkie. “Livestock manure has significant resource potential -- all animal manures are valuable sources of crop nutrients and manure represents a substantial bioenergy resource if processed by anaerobic digestion.”
Dr. Wilkie discussed the technology at World Pork Expo during the Environmental Information Center session on Ag Waste and Nutrient Management, which was sponsored by Engineered Storage Products Company, manufacturers of Slurrystore® waste management systems.
According to Dr. Wilkie, anaerobic digestion uses microorganisms to transform waste under oxygen-free conditions into biogas, soluble nutrients and additional cell matter, leaving salts and refractory organic matter. Raw biogas typically consists of methane (60%) and carbon dioxide (40%), water vapor and trace amounts of hydrogen sulfide. The biogas produced can be converted to electricity or collected and used as a direct energy source. For example, the University of Florida utilizes the biogas to heat water for the dairy’s milking parlor. Biogas also can be upgraded and fed into natural gas pipelines. Unlike fossil fuels, use of renewable resources represents a closed carbon cycle and therefore does not contribute to increases in atmospheric concentrations of carbon dioxide. In effect, anaerobic digestion is a carbon dioxide neutral solution.
Anaerobic digestion occurs naturally in anaerobic environments, such as sediments, soils and animal intestinal tracts. “The biogas cycle is a natural process -- we are just learning to manage and enhance it,” explained Dr. Wilkie. The process can be used for biomethane production from animal manures, crop residues, and industrial and municipal wastewaters, as well as from purpose-grown energy crops.
Under controlled conditions, anaerobic digestion offers a holistic waste treatment solution, stabilizing wastewater, controlling odors, reducing pathogens, minimizing environmental impact from waste emissions, maximizing resource recovery and working as a net energy producer. “Many of the benefits of anaerobic digestion translate directly to practical and economic benefits that contribute to long-term sustainability,” stated Dr. Wilkie.
Odorants in livestock manure result primarily from the partial decomposition of organic matter by anaerobic microbial activity. In many storage systems for livestock manures, therefore, an unbalanced fermentation is created and objectionable odors result from the accumulation of volatile malodorous intermediates. However, in an anaerobic digestion system designed and operated for biogas production, the two phases of acid fermentation and methane production are kept in balance and odorants are degraded to achieve permanent odor reduction. Thus, at the farm level, anaerobic digestion can stabilize manure, allowing it to be stored more easily and for longer periods. Handling costs also are reduced because the digested effluent pumps more easily than raw animal manures. When applied correctly, the by-products of anaerobic digestion (liquid fertilizer and compost) decrease the need for synthetic fertilizers and soil conditioners that are produced using less sustainable methods, providing cost savings and environmental advantages. In addition, after anaerobic digestion, the nutrient content of the wastewater is more predictable, allowing it to be applied more precisely within a fertilizer management program. “Anaerobic digestion systems can provide significant benefits to aid in meeting the increasing environmental regulations and public pressures on farmers and others regarding organic waste handling and disposal, as well as providing green energy,” concluded Dr. Wilkie.
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SIDEBAR
MAKING AN ANAEROBIC DIGESTER SYSTEM WORK FOR YOU
A successful anaerobic digestion system should be easy to operate and cost-effective, according to Dick Nelles, Agricultural Sales Manager at Engineered Storage Products Company (the manufacturer of Slurrystore). It also should be characterized by a consistent and significant reduction in volatile solids and production of methane rich biogas, plus discharge an effluent with less odor, pathogenic organisms and weed seeds than what was present in the incoming waste.
If considering an anaerobic digester system, Nelles says to first select a successful team of partners. “The selection of an engineering consultant or developer is a critical decision,” said Nelles. “Find someone to manage the process of transforming a feasible idea into a functional facility.”
Second is to select the proper biogas system design and components. “The largest component of a digester system is the digester tank,” added Nelles. “Engineered Storage Products Company has been manufacturing and installing glass fused to steel structures since 1949. We have been designing tanks used in digester systems for more than 25 years. Plus, research has shown that an above-ground mixed reactor, similar to the tanks designed by Engineered Storage Products Company, is very efficient.”
Most Engineered Storage Products dealers also can supply reception pit pumps, manure storage structures, manure spreader tanks and solids separators. In addition, added Nelles, “we can help complete the installation of many of the digester components.”
To size a digester, Nelles says to take the daily manure production in an operation and multiply it by 20.
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Engineered Storage Products Company is located in Dekalb, Illinois. They are the leading manufacturer of glass-fused-to-steel structures in North America, including the well-known Harvestore® and Slurrystore® brands. For more information, please call 815-756-1551.
