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Public Radio's Environmental News Magazine (follow us on Google News)

Science Note: Recycling Manure

Air Date: Week of

Engineers in Missouri are turning pig waste into pave roads. Honah Liles reports.


GELLERMAN: Just ahead – nature gone wild thanks to scientists. But first, this note on emerging science from Honah Liles.


LILES: Pigs are about to hit the road, or at least, their waste is. Engineers at the St. Louis design firm Innoventor have created a device that converts pig waste into something useful: bio oil. The system works like a pressure cooker: The pig waste slurry is pumped from the pits under the barn, heated and pressurized.

This turns the solids into bio oil, leaving a byproduct called black water. The black water and bio oil are separated as they leave the reactor. The engineers say that because this black water retains nutrients from the waste, it could potentially be used as a fertilizer. The bio oil is also useful. It might become an energy source, and already it is being used as an asphalt-binder.

It’s currently being tested on a stretch of road outside St. Louis, Missouri. Both Innoventor and the Missouri Department of Transportation plan to monitor the condition of the road over the winter, to see if the bio oil binder can stand up to a season of freezing and thawing. The bio oil conversion process is quick, so a 10,000-hog farm could produce about 10 to 15 barrels each day. That could generate revenue for the farmers, as well as deal with an environmental problem. Because the pig waste is pumped directly to the converter, it eliminates the need for smelly manure lagoons.

If the waste-derived asphalt holds up over the winter, little piggies could soon be heading to market on a road they helped pave. That’s this week’s Note on Emerging Science. I’m Honah Liles.



Manure Manager Magazine article

Innoventor’s info page


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