Lowa State Engineer Scales Up Process That Could İmprove Economics Of Ethanol Production

Iowa State University's Hans van Leeuwen has moved his research team's award-winning idea for improving ethanol production from a laboratory to a pilot plant. Now he knows the idea, which produces a new animal feed and cleans water that can be recycled back into ethanol production, works more efficiently in batches of up to 350 gallons than on a lab bench.

"We're learning we can reliably produce good quality and good quantities," said van Leeuwen, Iowa State's Vlasta Klima Balloun Professor of Engineering in the department of civil, construction and environmental engineering.

What van Leeuwen and a team of Iowa State researchers are producing is a fungus, Rhizopus oligosporus, that makes a high-quality, high-protein animal feed from the leftovers of ethanol production. The process of growing the fungus also cleans water from ethanol production so that it can be recycled back into fuel production. And the process, called MycoMeal, could one day produce a low-cost nutritional supplement for people.

The project has two patents pending and has won several major awards, including a 2008 R&D 100 Award presented by R&D Magazine, the 2008 Grand Prize for University Research presented by the American Academy of Environmental Engineers and a 2011 Honor Award in University Research from the academy. The project also contributed to R&D Magazine naming van Leeuwen its 2009 Innovator of the Year.

The research team working on the project is led by van Leeuwen and includes Nick Gabler and Mike Persia, assistant professors of animal science; Mary Rasmussen, a post-doctoral research associate in food science and human nutrition; Daniel Erickson, Christopher Koza and Debjani Mitra, graduate students; and Brandon Caldwell, a graduate of Iowa State. The project is supported by a three-year, $450,000 grant from the Iowa Energy Center and a Smithfield grant from the Office of the Iowa Attorney General. Lincolnway Energy of Nevada, Cellencor Corp. of Ames and Iowa State's Center for Crops Utilization Research and BioCentury Research Farm are also supporting the project.

Here's how their process works to improve dry-grind ethanol production:

For every gallon of ethanol produced, there are about five gallons of leftovers known as stillage. The stillage contains solids and other organic material. Most of the solids are removed by centrifugation and dried into distillers dried grains that are sold as livestock feed, primarily for cattle.

The remaining liquid, known as thin stillage, still contains some solids, a variety of organic compounds and enzymes. Because the compounds and solids can interfere with ethanol production, only about 50 percent of thin stillage can be recycled back into ethanol production. The rest is evaporated and blended with distillers dried grains to produce distillers dried grains with solubles.

The researchers add fungus to the thin stillage and it feeds and grows into a thick mass in less than a day – van Leeuwen calls it "lightning-speed farming." The fungus removes about 60 percent of the organic material and most of the solids, allowing the water and enzymes in the thin stillage to be recycled back into production.