Managing Manure

CELINA - County officials have applied for a nearly $1 million federal grant to conduct an extensive yearlong exploration of technology that removes nutrients from manure after two summer pilot tests yielded positive results.

Ag Solutions Coordinator Theresa Dirksen said she has applied for $900,000 through the U.S. Environmental Protection Agency Science to Achieve Results program.

If awarded the grant, Ag Solutions would facilitate a yearlong pilot test at a Mercer County swine farm in the Grand Lake Watershed. It would, among other inquiries, further assess potential operational costs of a KDS unit and QuickWash technology.

Summer pilot tests of the equipment showed that it's capable of removing phosphorus - the preferred food source of toxic blue-green algae that have plagued Grand Lake - at about a penny per treated gallon, an amount considered affordable for adoption at the local level.

Still, a more in-depth, yearlong assessment of the equipment is necessary to determine its economic and operational viability.

"I don't fully understand the demands that it would have on a farmer yet. It's got to be something that's simple to operate if it's going to be implemented on a wide-scale basis," Dirksen told the newspaper. "And I think we've got to find that market for the off-products, too."

A KDS unit separates manure solids from liquids. QuickWash technology involves adding acid to manure to drop the pH level and to make the phosphorus soluble. Solids are then separated with a dewatering machine, the pH level is restored using lime, and phosphorus is then precipitated out as calcium phosphate.

"You solubilize the manure, which forces your phosphorus into the liquid form and then you precipitate that phosphorus out using lime. So you're adding an acid, then you're adding a lime to form calcium phosphate," Dirksen explained.

This summer, the two units were tested at a swine farm in McComb and a dairy farm in Forest, Dirksen said. They cost $50,000 and were largely funded by Blanchard Demonstration Farms - a Great Lakes Restoration Initiative project designed to showcase and demonstrate leading-edge conservation practices - Ohio Dairy Producers Association and other entities.

"The ultimate goal of both of these was to demonstrate the ability to reduce phosphorus in the manure and look at the economics," Dirksen said. "How low could we push the cost by still achieving at least a 50% or greater reduction in phosphorus?"

During the course of the pilot tests officials discovered they could still achieve good results without adding acid, which could lower the cost of the process. The lime, to which the calcium and magnesium bind and pull out the phosphorous, was sufficient by itself, she said.

"We're just able to pull out a significant amount of soluble phosphorus without having to acidify, and that's probably just based on the characteristics of the manure, in and of itself." she said. "We're not using any polymers and we're mixing lime on site."

Officials were able to remove phosphorus from the swine manure at a cost ranging from 0.14 to 1.23 cents per gallon treated and from the dairy manure at a cost ranging from 0.75 to 1.27 cents per gallon treated.

To offset the capital and operating investment of the process, farmers would likely need to sell the phosphorus that is precipitated out as calcium phosphate, which can be used as fertilizer.

"This has got value, so we want to develop the market around this," Dirksen said.

The pilot test results were good, but many unknowns remain, she said.

"Are we going to be able to sell the calcium phosphate, and how do we get the calcium phosphate dry?" she asked. "What we did at the pilot was basically siphoned it off, and then we would air dry this or dry it in the sun, which worked fine. We could get it nice and dry. But when you're taking a full-scale installation that's running all the time that's not feasible."

Dirksen's job is to search for affordable manure-management methods to help area farmers reduce nutrient runoff blamed for toxic algal blooms in Grand Lake.

Nutrient runoff comes from many sources, but in the Grand Lake Watershed, studies show it's mostly from farmland in the 58,000-acre, livestock-heavy watershed. Phosphorus found in manure is the algae's favorite food source. The toxins can harm the liver, cause gastrointestinal symptoms and rashes, and can sicken people and kill small animals.