Vermont Dairy Farm Spins Manure to Take Out Phosphorus

One Vermont dairy farm is taking a novel approach to reducing polluted runoff in Lake Champlain by spinning its manure in a centrifuge to remove some of the phosphorus that has contributed to toxic algae blooms.

Machia and Sons Dairy LLC is believed to be the first farm in Vermont to use the technology for phosphorus removal after having it installed last year in a pilot project with Burlington-based Native Energy.

A screw press removes the solids from the manure that are then decomposed into bedding for the cows. The manure liquid is put through the centrifuge that rapidly spins it in a large canister to remove half of the phosphorus that then can be sold as a soil additive.

Phosphorus is a nutrient that comes from a number of sources including fertilizer and manure. An excess amount of it — in runoff from rain, snowmelt or erosion — feeds toxic algae blooms in the lake. The state says 40 percent of the phosphorus flowing into the lake comes from farms; the rest comes from roads, parking lots and discharges from municipal wastewater treatment plants.

In June, the U.S. Environmental Protection Agency released its final phosphorus reduction goals for the lake, calling for a decrease of 33.7 percent in the entire lake and 64.3 percent in Missisquoi Bay in the northern end of the lake, an area known in the state for its dairy farms.

Machia and Sons is one of the larger farms in Vermont, where 725 cows are milked. Like some other local farms, it has taken steps to reduce phosphorus runoff such as planting cover crops and expanding or adding vegetative buffer strips between fields and ditches. The effort is to help clean up the lake and to "keep us in farming, keep the community happy. At the end of the day, that's what it's all about," said Dustin Machia, one of the farmers.

The family business invested about $100,000 in the screw press and centrifuge project. The rest of the $525,000 cost is being covered by Native Energy, a seed grant from Green Mountain Power and the purchase of the expected reduction in greenhouse gases from the project by Ben & Jerry's, according to Native Energy.

Now the Machias are seeking a market for the phosphorus.

Less than a handful of centrifuge manufacturers are working with the dairy manure market in the U.S., according to Josh Gable of manufacturer Centrisys, of Kenosha, Wisconsin, which currently has 10 installations of centrifuges processing dairy manure across North America. At least four installed in the last four years have the primary purpose of removing phosphorus, he said by email.

"Despite depressed milk prices we expect to add to our installation base for manure applications removing phosphorus ... this year as environmental pressures continue to be applied to dairymen in sensitive areas across the U.S.," he said.