The 1,000-liter (left) and 500-liter fermentors.
The 1,000-liter (left) and 500-liter fermentors.

Biofuels Research Trials Underway With New BCRF Fermentors

The U.S. Department of Agriculture funded the acquisition of a 500-liter and a 1,000-liter fermentor for the BioCentury Research Farm (BCRF). The Center for Crops Utilization Research (CCUR) and the College of Agriculture and Life Sciences (CALS) received two USDA special appropriation grants this past year for the purchase. The two grants covered $470,000 of the $622,000 total cost, with the balance provided by CCUR, CALS, and the Plant Sciences Institute.

The 500-liter fermentor is fully installed and, to date, four projects have made use of it. Former food science and human nutrition faculty member Sam Beattie led two of the projects. The first project used oleaginous yeast to produce oil from glycerol, a byproduct of biodiesel production.

"The concept of the project was to take biodiesel byproducts to create oil that could be processed into more biodiesel," said Larry Johnson, director of CCUR and the BCRF

The other project headed by Beattie grew oleaginous yeast on fish oil. The yeast encapsulated the fish oil and was fed to cattle.

"This new feed should changed the composition of the milk, causing the cattle to produce milk high in omega-3 fatty acids," said Johnson.

"The 500-liter fermentor performed well during these trials and showed that oleaginous yeast can readily utilize biodiesel glycerol and also incorporate fish oil in larger scale fermentation schemes," said John Strohl, assistant scientist and fermentation facility manager.

Hans van Leeuwen, Vlasta Klima Balloun professor of civil, construction and environmental engineering, headed the other two projects. One project focused on fungal fermentation based on thin stillage from corn ethanol production. An inoculum of Rhizopus oligosporus fungi was added to thin stillage, aerated and grown to about 15 grams of dry weight fungal biomass per liter within 24 hours, and was harvested by passing through a relatively course screen.

"This project produced high-value feed products and reduced energy and water usage," stated van Leeuwen.

Van Leeuwen's team won an R&D 100 Award for the fungal research development work in 2008 and awards from the American Academy of Environmental Engineers (AAEE) in 2008 and 2011.

Van Leeuwen's other project converted lignocellulose to oil via oleaginous yeast.

"Corn fiber was pretreated by cultivating white-rot fungi on the material during solid-state fermentation," said van Leeuwen.

The hydrolysate was then used as substrate to cultivate Cryptococcus curvatus yeasts in the fermentor. These were harvested by centrifugation and found to contain oil, about 35% of the dry mass.

"The triglyceride oil was found to be quite suitable for biodiesel production," stated van Leeuwen. The fungal oil production research won an AAEE award and an R&D 100 Award in 2009. Van Leeuwen was named Innovator of the Year in 2009 by R&D Magazine.

The 1,000-liter fermentor has been installed and recently underwent initial trials to determine a baseline using ethanol fermentations.

"The initial trials have been completed and we are currently running a corn ethanol fermentation in which soy skim is used in place of the standard water component," said Strohl.

According to Johnson, this fermentor will be used very soon to test a new corn degerming process that could allow recovery of edible corn oil in a dry grind ethanol plant. Another upcoming project will evaluate new corn and soybean biorefinery concepts.

The fermentors are available for research and fee-for-service projects. Contact John Strohl at 515-294-0306 or jstrohl@iastate.edu to schedule use of the fermentors.


Hui Wang, CCUR pilot plant manager, and John Strohl are running a 1,000-liter corn ethanol fermentation and downstream decanting.