When Manure Happens, Scientists Convert it to Products

If you thought cow patties were just something to avoid stepping in, consider: In the future they could help make plastics, antifreeze, cosmetics, even deodorants.

Funded by a grant from the Department of Energy, engineers and animal scientists at Washington State University and Pacific Northwest National Laboratory in Richland, Wash., are exploring ways of extracting valuable chemicals from manure. The waste could also provide undigested and purified proteins for making fresh feed for cattle.

"Look at what's in manure," says Don Stevens, project manager with the Richland lab. "There's a lot of carbohydrates and proteins … of course the product is real wet."

A single cow produces about 100 pounds of wet manure a day, of which about 20 pounds is dry waste, according to Joe Harrison, an animal scientist at WSU. A cow's diet includes about 18 percent protein and 30 percent carbohydrates, and about a third to a half of what a cow eats comes back out.

Researchers at WSU are looking at ways of extracting proteins and amino acids from manure for processing new animal feed. Harrison says such recycled feed would only be fed to non-dairy cows to safeguard against any possible contamination of milk products.

Other Products, Too

Meanwhile, Stevens and his team are exploring using manure's carbohydrates for making chemicals.

Glycols, diols and other chemicals are used in many plastic products and cosmetics and are normally processed from petroleum. Rather than drawing a resource from underground, the researchers hope to scoop up another, cheaper material from farm stalls. They say the abundance of carbohydrates in animal manure could provide the building blocks for chemical production.

The process that would be used to process the patties is not new. The Richland lab has already developed ways of extracting chemical building blocks from corn mash left over from ethanol production and grains remaining from wheat mills. Manure processing would employ similar methods, although it would be a messier product.

"Manure is a dirtier stock," says Stevens. "It not only has carbohydrates but also rocks and stones and sticks and who knows what."

Plentiful Resource

Why bother tinkering with such a stinky resource? Because it's plentiful. In fact, about 160 million tons of animal waste is deposited in the United States annually. Farmers usually spread the manure for drying or funnel it into lagoons and then extract and dry it for spraying on farmland as fertilizer.

But dried manure isn't ideal fertilizer and the product is worth only about a penny a pound. If used to manufacture chemicals, Stevens estimates cow's, chicken's and pigs' leavings could be valued at up to 40 cents a pound.

Most important, the process could provide one way to reduce harmful leaching of phosphates and sulfates from wet manure into waterways and lakes. Stevens says federal protection laws for salmon have forced farmers to stop the common practice of draining liquid manure into streams and rivers.

Rather than polluting fresh water sources, Stevens hopes manure could instead be carted to chemical processing plants and converted into more useful materials. There are no estimates yet on the cost of processing the manure for chemicals, but Stevens says it should be less costly and twice as energy efficient as using petroleum.

While the Richmond lab and WSU are starting with cow manure, Harrison says they won't discriminate when it comes to waste since hog and poultry manure could prove equally valuable.

Although Harrison adds, when it comes to handling manure, some kinds are preferable to others.

"Swine and poultry waste, I'd rather not touch," he says. "I'd rather handle cow manure. But that's just a personal thing."

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