The McLanahan Nutrient Separation System, developed at Michigan State University (MSU), combines an anaerobic digester with an ultrafiltration, air stripping and reverse osmosis system to produce clean water.
“If you have 1,000 cows on your operation, they produce about 10 million gallons of manure a year,” said Steve Safferman, MSU associate professor of biosystems and agricultural engineering. “About 90 percent of the manure is water but it contains large amounts of nutrients, carbon and pathogens that can have an environmental impact if not properly managed.”
While turning the manure into clean water makes environmental sense, the team also is conducting research on how it can make good financial sense for farmers. And in some cases, it could have a significant impact on the long-term viability of the farm.
“Here in Michigan we have a tendency to take water for granted,” Safferman said. “But out west, for example, where drought remains an issue, the accessibility of clean water could make the difference between a farm remaining viable or going out of business.”
The process “goes beyond a typical digester,” said Jim Wallace, a former MSU student who earned his doctorate under the direction of Safferman and William Bickert, former professor of agricultural engineering. And it does this by extracting nutrients from the manure that can be harmful to the environment and can be re-used as fertilizer. “For example, we’re able to capture a large percentage of the ammonia that would otherwise be lost in the atmosphere,” said Wallace, who now works for the McLanahan Corp., which is working to develop the technology. “Ammonia is a negative from an air-quality standpoint.”
Currently the system produces about 50 gallons of water from 100 gallons of manure. Wallace said the goal is to increase that number to about 65 gallons.
Work on the project began about 10 years ago at MSU, under the direction of Bickert, who saw the potential of anaerobic digesting.
It’s hoped the Nutrient Separation System will be ready for commercialization by the end of this year.