Manure separation shows promise for better nutrient management

By Dusty Sonnenberg, Ohio Field Leader

For every 1,000 gallons of manure produced on Dwayne Stateler’s Hancock County hog operation, there are 50 pounds of nitrogen, 28 pounds of potassium, 20 pounds of phosphorus, and 5 pounds of sulfur available to benefit crops produced on the farm.

Duane and Anthony Stateler grow corn, soybeans and wheat on approximately 600 acres in Hancock County and also operate a 7,200-head wean to finish swine operation. The Stateler farm is one of three operations in the Blanchard River Demonstration Farms Network — a joint partnership between U.S. Department of Agriculture Natural Resources Conservation Services and the Ohio Farm Bureau Federation. The Blanchard River Demonstration Farms Network is a Great Lakes Restoration Initiative project designed to showcase and demonstrate leading edge conservation practices to improve Great Lakes water quality. The Statelers have committed 243 acres to the Blanchard River Demonstration Farms Network and they are always looking to improve the efficiency of nutrient management in their operation.

Over the years, the Statelers have used various conservation practices on the farm to better manage those valuable nutrients in the manure including: variable rate manure application, planting cover crops, and water control structures for drainage water management. They also have installed a phosphorus removal bed and conduct edge-of-field monitoring of the water coming off their farm both through the tile and from surface drainage. One of the more recent areas of manure management the Statelers are exploring deals with treating their swine manure to remove the solids and lower the phosphorus and nitrogen components.

“We are always open to try new things. The goal is to improve the environmental impact as well as enhance the economic returns to the farm,” Stateler said. “If there is any way we can get away from running a full manure tanker for each acre to get the nutrients we need, or even condense it to cover more acres, that would be a benefit. Hopefully this technology will allow us to be more efficient in how we deliver these nutrients.”

To accomplish this, the Stateler’s are working with Rick Johnson, a researcher with Applied Environmental

Solutions, an Ohio based company that uses existing technologies and attempts to align them with agricultural applications. Johnson’s background is in the municipal waste industry, but in recent years he has shifted his focus to agriculture. Johnson has worked with a dairy farm’s lagoons and anaerobic digester, a poultry operation with the egg wash water and manure solids, and now with the Statelers he is focusing on better managing the nutrients in swine manure.

“The key is to make it cost effective,” Johnson said. “We know the technology works, but we want to be able to determine what it will cost, per unit of phosphorus, to lower the manure to a specific level. I would like to be able to develop an economic curve and tell a farmer what the amount of phosphorus is that can be removed at a given price and percentage based on this data. The goal is not for the farmer to change his operation, but find a technology that is robust enough and economical enough to make it fit his operation.”

Johnson and his team at Applied Environmental Solutions are testing two different technologies. The first is a KDS Multi-Disk Roller Separator manufactured by Kendensha Co., Ltd in Japan. The KDS Separator is compact, energy efficient and self-cleaning.

“This is a low-cost solid separator that is cheaper than a centrifuge or other technologies,” Johnson said. “For some operations, mechanically separating the solids in the manure from the liquids is sufficient to lower the phosphorus to their desired level. The two products — solids from the manure and the liquid — can then be stored and applied separately.”

Manure is poured into the upper section of the machine and the movement through a series of

contiguously placed oval plates separates the solids from the liquids. Additionally, through the continuous rotation of multiple oval plates between the slits, the separated solid is transferred while preventing the slits from clogging. The solids emerge from the separator with moisture contents from 20% to 30% moisture for hog manure and 25% to 30% for cattle manure, according to Kendensha Co. specs.

Once processed in the KDS Separator, Johnson and the Statelers are also looking at a second technology being tested to further refine the liquid portion of the manure. The equipment is contained in a trailer.

“Because every farm is unique in terms of the type of animals raised, the feed rations, and thus characteristics of the manure, the liquid initially is tested in a mobile laboratory to determine specific parameters of the product and measure the pH,” Johnson said.

Based on the specifics of the liquid portion of the manure, it is then run through a series of stages in which the pH is adjusted and additional fine particles are removed. Then the remaining phosphorus is precipitated out of the solution with the addition of a hydrated lime product. The reaction creates a slurry containing calcium phosphate and water.

“Initial testing has found that this two-step approach removes as much as 87% of the phosphorus,” Johnson said. “The calcium phosphate can be used on the farm or potentially sold as an additional revenue stream. We are also looking at the nitrogen component that remains in the water and the value in that.”

Theresa Dirksen is the coordinator for Mercer County Ag Solutions, and initially coordinated projects with Johnson and farmer cooperators in Mercer County. She said, once separated, the different components of the manure can be used accordingly based on the needs and situation of the cooperating farmers.

“Ideally the water could be used for irrigation or fertigation of growing crops and the solids separated from the manure could be transported to areas with less livestock concentration where it is needed,” she said.

Projects like this are just one part of the broad nutrient management efforts being researched and put on display through Blanchard River Demonstration Farms Network. The manure separation technology demonstration on the Stateler farm was part of a Manure Spill Training Day held this summer for farmers, manure applicators and any organization/government agency that is potentially involved with a manure discharge or spill. At the event, Terry Mescher with the Ohio Department of Agriculture Review of Rules and Authorities of Government Agencies talked about the importance of contacting the local Soil and Water Conservation district in the case of a manure spill and following the proper chain of command. He

pointed out the importance of documenting every step (including an up-to-date weather forecast) and following all protocols in all cases in the event that a problem could arise. Matt Heckler, with the Mercer Soil and Water Conservation District conducted an in-field demonstration of how to remediate manure discharges through in-channel aeration, damming stream and/or surface flow in field, and the careful use of a tile plug and pump out pits from tile lines. When things do not go as planned, he emphasized the extreme importance of rapid response to a manure spill to minimize environmental impacts and costs to the farmer.

For more on the KDS Separator visit kendensha.com/pdf/slit_english.pdf. For more on the Blanchard River Demonstration Farms visit blancharddemofarms.org.

Ohio Field Leader is a project of the Ohio Soybean Council. For more, visit ohiofieldleader.com.

Manure separation shows promise for better nutrient management