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Research Uses Kenaf To Lessen Swine Odor
MISSISSIPPI STATE -- A product needing a niche of its own may have secured a foothold in the hog industry as research is showing kenaf offers a way to reduce swine odors.
Dr. Tim Burcham, associate agricultural engineer with the Mississippi Agricultural and Forestry Experiment Station, is testing a bio-reactor he developed to filter and biologically treat wastewater from hog production facilities.
The main goal of the research is odor reduction and wastewater treatment. Burcham's interest in the versatility of the kenaf plant spurred the development of this research.
"I wanted to find something that kenaf was better at than other biological products," Burcham said. "There's potential for this system to provide a cost-effective odor control using only natural products."
Kenaf is a woody plant ideally suited to growth in Mississippi. Six to eight tons of usable kenaf can be grown per acre. The whole plant can be chopped up and used for the filter system. The biological "slimes" accumulate in the kenaf filters which are removed when full and treated in a composting facility. This compost can be used on crops or sold as a valuable fertilizer or soil amendment.
"The treated wastewater and kenaf compost can be used to provide moisture and nutrients for growing kenaf and other forage crops," Burcham said. "Swine producers can use the wastewater and kenaf compost effectively to support the agricultural process."
In most operations, hogs are kept on wire grates above a water tank. Waste falls through and the water is flushed out to lagoons every few days. Swine operations' odors come from wastewater storage lagoons, swine housing facilities and fields on which wastewater is spread.
By reducing the wastewater's odor, Burcham's system reduces the odors associated with hog production. Researchers are still collecting data, but preliminary results are promising.
The method features a kenaf filter and bio-reactor, and a pump circulating the hog wastewater through the system. It is being tested on an experimental swine facility at Mississippi State University's South Farm.
Wastewater in the test pit trickles through the filters seven times a day during a seven-day test cycle, being treated and stabilized as it passes through. Burcham said the test system is similar to those used by municipal water systems, except it uses kenaf in the filter. On the other side of the barn, a control group of pigs is used for comparisons.
Early data indicates that the filter system reduces nutrients in the wastewater. While this reduces odors, it is also a disadvantage because many swine producers use the wastewater as fertilizer for forage production.
"We have found that if we're going to reduce the odor, we may have to sacrifice some of the nutrient content," Burcham said.
Because of the reduced nutrient wastewater produced in this system, hog producers may need less acreage to spread the wastewater in an environmentally sound manner. This provides a larger buffer between the hog operation and its neighbors.
Dr. Nancy Cox, assistant MAFES director, said odor is the Mississippi hog industry's largest problem.
MSU's food science and technology department trained an odor panel to objectively assess the degree of odor and so evaluate the performance of the kenaf filter system and other technologies. Cox said the odor panel determined that the kenaf filter dramatically reduced the odor from the wastewater.
"Odor is totally subjective and you must train to really tell the difference," Cox said. "It is very important to be able to measure reliably and objectively the odor and whether there is a change. There is no machine at this time that works as well as the human nose to detect odors like these."
The research is a cooperative effort between MAFES, the Forest Products Lab, and MSU departments of food science and technology, chemical engineering, agricultural and biological engineering, plant and soil sciences and agricultural economics.