Enzyme study shows DDGS dewatering applications
Ethanol Producer Magazine
By Holly Jessen November 22, 2011
A one-month plant trial showed a commercial enzyme could help extract water from distillers grains, saving natural gas, electricity and water used in the ethanol process. More work needs to be done, said David Johnston, a sustainable biofuels and co-products food technologist for the USDA Agricultural Research Service, adding that now that the idea is out there, ethanol plants can start testing the idea internally. “I think that there would be some other process benefits that we couldn’t tell in a one-month trial,” he said. “The enzyme does something that should actually help in some of the unit operations, as far as maintenance and that sort of thing, but it’s something that you would really need to do in the long run to show and prove.”
The study was conducted at Center Ethanol Co. LLC, a 54 MMgy ethanol plant in Sauget, Ill. For the study, one pound of an enzyme supplied by Genencor was added for each 1,000 pounds of corn. Similar products from other ethanol enzyme makers could also be used, Johnston said. The enzyme, which typically is used as a cellulose preparation, was added as an additional enzyme during fermentation with no added equipment necessary.
As a result, scientists found that the natural gas usage for the dryer was reduced by 14 percent because the enzyme boosted water extraction in the centrifuge. “The enzyme is believed to disrupt that physical structure that the water is binding to, basically it makes it so it doesn’t hold on to the water as tightly,” he said. Using an existing economic model of ethanol production, researchers found that using the enzyme to dewater the stillage resulted in a reduction of natural gas usage by 12 percent and a reduction of electricity consumption by 2.4 percent. Water recycling opportunities can also be increase because more suspended solids are removed during the decanter centrifuge operation, Johnston added. In all, researchers calculated a 10 percent water reduction with the use of the enzyme for dewatering.
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