Iowa State researchers use fungus to improve corn-to-ethanol process

Iowa State University researchers, left to right, Anthony L. Pometto III, Hans van Leeuwen and Mary Rasmussen display the 2008 Grand Prize for University Research recently presented to their research... Click here for more information.

AMES, Iowa – Growing a fungus in some of the leftovers from ethanol production can save energy, recycle more water and improve the livestock feed that’s a co-product of fuel production, according to a team of researchers from Iowa State University and the University of Hawai’i.

“The process could change ethanol production in dry-grind plants so much that energy costs can be reduced by as much as one-third,” said Hans van Leeuwen, an Iowa State professor of civil, construction and environmental engineering and the leader of the research project.

Van Leeuwen and the other researchers developing the technology – Anthony L. Pometto III, a professor of food science and human nutrition; Mary Rasmussen, a graduate student in environmental engineering and biorenewable resources and technology; and Samir Khanal, a former Iowa State research assistant professor who’s now an assistant professor of molecular biosciences and bioengineering at the University of Hawai‘i at Mânoa – recently won the 2008 Grand Prize for University Research from the American Academy of Environmental Engineers for the project.

“Those chosen for prizes by an independent panel of distinguished experts address the broad range of modern challenges inherent in providing life-nurturing services for humans and protection of the environment,” according to a statement from the academy. “… Their innovations and performance illustrate the essential role of environmental engineers in providing a healthy planet.”

The Iowa State project is focused on using fungi to clean up and improve the dry-grind ethanol production process. That process grinds corn kernels and adds water and enzymes. The enzymes break the starches into sugars. The sugars are fermented with yeasts to produce ethanol.

The fuel is recovered by distillation, but there are about six gallons of leftovers for every gallon of fuel that’s produced. Those leftovers, known as stillage, contain 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 from corn and fermentation as well as 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.