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Pig farming doesn't have to be dirty

Posted: Sunday, April 07, 2002

Large-scale confined pig production creates the opportunity for a degree of environmental protection that cannot be achieved in smaller less intense operations. Although this potential has not been achieved in every situation, it is a potential available to a community if it wishes to make a commitment to that quality of development.

My interest is in promoting the development of livestock and poultry operations that are an economic asset to their community and are operated in a way that there are neither odor nor water-quality assaults. Technologies and management measures are available to insure these levels of performance.

Manure management is the key to both odor and water pollution control. Pigs in confinement do not perspire, and, therefore, if they are maintained in a clean environment, there is no odor from the pigs.

Most frequently, pigs in confinement buildings are housed on slotted floors so the manure and urine are immediately separated from the pigs. The manure drops into a shallow channel from which it can be flushed once or twice daily to prevent anaerobic decomposition within the building. It is important at this stage of the process that the flush water be odor free. This water is recycled in order to minimize water use and to also reduce the amount of water that needs to be stored for summer application to crop, pasture or forest land.

The flushed manure is pumped to an aerobic digester in which a mixture of bacteria breaks down the manure constituents, finally yielding a mixture of carbon dioxide and methane, commonly called biogas. This biogas in excess of that used to warm the digester can be used to heat buildings, or it can be used in an engine to power a generator to produce electricity that can be sold to the local utility company as a source of renewable energy.

Also while the manure is in the digester, the nitrogen is converted to ammonia. A large facility creates the opportunity for the ammonia, which is in the liquid effluent from the digester, to be reclaimed and marketed as ammonium sulfate or an alternate high nitrogen fertilizer ingredient. The ammonia stripping, like the anaerobic digestion, is done in an enclosed system so there is no exposure to outside air or for odor to escape.

The liquid stream from the anaerobic digester will typically be split in two streams. A portion will be placed in a small aeration basin for aerobic treatment prior to reuse as flush water, and the other will be discharged into a covered, impermeable basin for storage prior to application to land during the summer growing season.

The material in the storage basin will be covered to prevent odor escape.

The stored material may be directly land-applied using conventional irrigation equipment, or, if weather conditions are such that this would create an odor issue, it can be run back through the aeration basin prior to land application. Land-application rates are determined based on the crop and its nutrient uptake rate. Neither water nor nitrogen or phosphorus need to be added in excess.

Under these conditions, there is a high degree of protection to both the surface and groundwater resources of the area. The local air environment is protected from odors by conducting all of the odor-generating operations in an enclosed tank system.

If technologies are available to handle pig manure in these ways, why all the horror stories about massive fish-kills in North Carolina and odor complaints in the Midwest? The answer is that there are pig producers more interested in maximizing short-term profits than in creating sustainable economic enterprises.

The important ingredient in any community considering an agricultural or industrial development has to do with establishing priorities. If environmental protection is a high priority not to be traded for short-term profitability or minimal investment, an environmentally friendly pig production can be established. This goal also requires community support and education in order to be achieved.

I write this letter not to support or hamper the development of a pig industry on the Kenai Peninsula, but to encourage decision-makers to consider the real issues and not be swayed by the actions of greedy developers in other areas and other times who moved ahead without a commitment to environmental protection.

I have devoted the last 30 years of my career to the development of technologies that make it possible for the pork industry to change. I am convinced that it will change. Developers, educators, regulatory officials and local citizens all have a role in that process of change.

J. Ronald Miner is on the staff of the biosource engineering department at Oregon State University.



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