Media contact: Dr. Mike Williams, Departments of Animal and Poultry Science, N.C. State University,
A five-year effort at North Carolina State University to identify alternative waste management technologies for the North Carolina swine industry has singled out a combination of technologies researchers consider “environmentally superior” to the lagoons and spray fields now used.
As director of the Animal and Poultry Waste Management Center in N.C. State's College of Agriculture and Life Sciences, Dr. Mike Williams led the effort to identify alternative waste management technologies. Williams recently left the Animal and Poultry Waste Management Center and is now a member of the faculties of the departments of Poultry and Animal Science at N.C. State. The initiative was funded by pork producers Smithfield Foods and Premium Standard Farms under agreements the two companies reached with the North Carolina Attorney General's office in 2000. Since then, experts from NC State University and elsewhere have been developing and evaluating alternative swine waste management technologies.
In a report dated March 8, Williams identifies a combination of waste management technologies that he has decided meet environmental and economic feasibility criteria for new and expanding hog farm categories as spelled out in what is perhaps more commonly known as the Smithfield Agreement.
One of the technologies identified treats the liquid portion of the waste stream from a hog farm. Williams also identified four technologies that treat the solid portion of the waste stream. He said in the report that the liquid treatment technology may be combined with any of the solid treatment technologies to create what the report calls an environmentally superior swine waste treatment system.
While the Smithfield agreement spells out environmental criteria technologies must meet, it also stipulates technologies must be economically feasible. In reports issued over the last two years, Williams found that five technologies met environmental criteria to be considered superior to the lagoon and spray field system now used on the majority of North Carolina swine farms. When those earlier reports were issued, however, an economic assessment had not been completed.
The economic assessment has now been completed, although there was disagreement among members of an advisory panel appointed by Williams as to what constitutes economic feasibility. The disagreement centered on the effect adoption of a waste management technology is likely to have on North Carolina's swine herd. Some members of the advisory group felt a technology should be considered economically feasible only if its adoption would have no effect on the number of pigs in the state. Others felt a technology could be considered economically feasible even if its adoption caused a reduction in the size of North Carolina's swine herd. Williams' report contains majority and minority reports stating each view.
Williams decided that a technology may be considered economically feasible even if it costs more than a lagoon and spray field system and if adopting the new technology would cause North Carolina's swine herd to shrink by as much as 12 percent.
The liquid treatment technology Williams approved was developed by Super Soil Systems USA. The solid and liquid portions of the waste stream are separated, then the liquid portion is treated in a series of large metal tanks. A composting system developed by Super Soil Systems was among the technologies approved for solid waste treatment. Waste is mixed with bulking materials such as cotton gin residue or wood chips, while a machine called a Compost-A-Matic is then used to mix the material daily.
Two other technologies approved for solid waste treatment treat waste by burning it.
One of the two technologies that burn waste does so in a chamber called a gasifier. Gasification involves burning a substance in a low-oxygen environment, which converts complex organic compounds in the substance to gases. It is possible to collect gases such as methane, carbon monoxide and hydrogen and make ethanol.
The second burning technology goes by the acronym BEST, for Biomass Energy Sustainable Technology, and includes two methods of separating the solid and liquid portions of the waste stream. Solids are then burned in a fluidized bed combustion system. In this system, the temperature is above 1,300 degrees F.
Both combustion systems produce ash, which contains nutrients and has value as a fertilizer.
The fourth technology is a high solids anaerobic digester that is known as ORBIT. The centerpiece of this system is an enclosed anaerobic digester, a large metal container. Waste is placed in the digester, where microbial activity converts it to biogas (methane and carbon dioxide).
Smithfield Foods provided $15 million to evaluate technologies, while the attorney general allocated $2.3 million from the Premium Standard Farms agreement, for a total of $17.3 million. In 2002 the attorney general entered a third agreement with Frontline Farmers, an organization made up swine farmers. While Frontline Farmers did not provide funding, the organization's membership agreed to work with the attorney general and N.C. State University to develop and implement environmentally superior technologies.
According to the agreements, technologies must be technically, operationally and economically feasible and eliminate the discharge of animal waste to surface or groundwater in order to be designated environmentally superior. Environmentally superior technologies must also substantially eliminate the release from swine farms of ammonia, odor and disease-transmitting vectors and airborne pathogens and eliminate contamination of soil or groundwater with nutrients or heavy metals.
Seventeen technologies were evaluated. In most cases, technologies were built full-scale on hog farms, then evaluated. Williams said several technologies were close to meeting the environmental criteria to be considered environmentally superior and might be able to do so with relatively minor adjustments.
In his report, Williams suggested that technology suppliers and researchers continue efforts to bring the cost of treatment systems down to the point it would be economically feasible to retrofit existing hog farms and that a process be developed to evaluate additional technologies. Williams said the evaluation effort funded under the Smithfield Agreement is now finished.
Williams also suggested in the report that efforts be made to “identify potential institutional incentives, public policies, and markets related to the sale of byproducts (with priority on energy production) that will reward farmers for utilizing technologies … that are shown to yield improvements and environmental benefits over the current lagoon spray field system.”
He added, “ The optimal method of achieving net cost reductions and even positive revenue flows from alternative technologies is to install targeted technologies on a sufficient number of farms to facilitate engineering improvements, value-added product market development, and other cost reduction methods.”
- Dave Caldwell, 919.513.3127 or firstname.lastname@example.org -
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