After 5 years of study, a combination of manure-treatment technologies has been determined as environmentally superior and economically feasible.
One technology treats liquid manure, while any of four others may be used to treat solids. “Any one of those four may be combined with the liquid treatment,” adds Mike Williams,
Williams notes that the approved liquid-manure treatment, developed by Super Soil Systems, uses a series of large metal tanks to treat liquid manure. A composting system that the company also developed, is one of four approved to treat manure solids. Manure is mixed daily with a bulking material such as wood chips in a machine called Compost-A-Matic.
Two other approved treatments actually burn the manure solids. One involves a chamber called a gasifier in which manure is burned in a low-oxygen environment. Through this process it is possible to collect gases and make ethanol.
The second burning technology is BEST, acronym for Biomass Energy Sustainable Technology. Solids are burned in a fluidized-bed combustion system at a temperature above 1,300° F. Both treatments produce ash, which has fertilizer value.
The fourth approved technology is a high-solids anaerobic digester known as ORBIT. Microbes convert manure solids to biogas (methane and carbon dioxide).
To meet environmental standards, a technology had to eliminate the discharge of animal manure to surface or ground water. It had to substantially eliminate the release of ammonia, odor and disease-transmitting vectors and airborne pathogens. It also had to eliminate contamination of soil or groundwater with nutrients or heavy metals.
Odor measurements were collected day and night near the hog facilities, as well as at various distances. For a technology to be approved, odor had to be confined within the property boundaries at a defined low concentration. The objective was to reflect real-life challenges that would help avoid problems with neighbors.
Two out-of-state technologies also were added to the study but they did not receive a share of the funding. One is
Williams points out that several technologies of the original 17 were close to meeting environmental standards, particularly reciprocating wetlands, a closed-loop system, an ambient-digester system and a sequencing-batch-reactor system.
Total costs for the technologies noted in the final report ranged from $80 to more than $400 per thousand pounds of steady-state live weight, annualized for 10 years. Most ran much higher than the costs for a lagoon and spray field.
All of the technology costs were based on newly constructed and retrofitted hog facilities. The costs included interest, investment payback, operating expense, labor and other real-world expenses.
Williams points out that the 23-member panel reached a consensus on nearly all project issues. The only significant split was on how much increase in pork-production cost could be justified.
He concludes that any combination of the approved technologies is economically feasible, assuming that the adoption would not have a drastic effect on the state’s hog population, which he cited as not more than a 12 percent reduction in annual market hogs produced.
Williams encourages technology suppliers and researchers to work on ways to reduce the costs. The best way to drive down costs is to get the alternative technology on enough farms to facilitate engineering improvements, value-added-product market development and the like.
Developing byproducts that generate income can help make a technology more affordable, says Williams. He expects other firms to develop alternative technologies that produce value-added byproducts, specifically those related to energy production. However, for pork producers to adopt new technologies, financial incentives such as state and federal cost-sharing and tax breaks will be needed, notes Williams.
The final report on technologies, as well as two earlier reports are available at http://www.cals.ncsu.edu/waste_mgt/
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They plan to recommend a specific technology to state lawmakers by September 2007. That’s also the date when the state’s moratorium, which bans producers from building new or expanding hog facilities, finally ends.