ARS | Publication request: ECONOMICS OF FIBER SEPARATION FROM DISTILLERS DRIED GRAINS WITH SOLUBLES (DDGS) USING SIEVING AND ELUTRIATION

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 10, 2006
Publication Date: March 10, 2006
Citation: Srinivasan, R., Singh, V., Belyea, R.L., Rausch, K.D., Moreau, R.A., Tumbleson, M.E. 2006. Economics of fiber separation from distillers dried grains with solubles (ddgs) using sieving and elutriation. Cereal Chemistry.83(4):p.324-330.

Interpretive Summary: In the past three years there has been a 100% increase in the production of fuel ethanol in the US. It is expected that this rapid rate of expansion will continue. Currently, 70% of all of the ethanol made in the US is via the fermentation of corn in a "dry grind" process that yields one co-product, Distillers Grains with Solubles (DDGS). DDGS is a good animal feed for ruminants, but its high content of fiber limits it from being used as a feed for non-ruminants. If the levels of fiber in DDGS could be reduced, it could become a valuable feed for poultry, swine, and aquaculture. Earlier strategies to remove the fiber have involved size separation (sieving) and separation of particles based on density. In a previously published report, we described a two-step process which combines sieving and density separation and this was the first approach that resulted in a removal of a significant amount of fiber from DDGS. In the current study we conducted an economic analysis of our previously-reported two-step process, focusing mainly on increasing profits by increasing the protein content in DDGS. We found that the levels of protein in the enhanced DDGS fraction could be increased by about 7-8%. We estimated that this would increase the profits of a typical dry grind ethanol plant by about $ 0.9 to 1.4 million per year, with a payback period of 1-2 years.

Technical Abstract: Separation of fiber from distillers dried grains with solubles (DDGS) provides two valuable coproducts: 1) enhanced DDGS with reduced fiber, increased fat and increased protein contents and 2) fiber. Recently, the elusieve process, a combination of sieving and elutriation was found to be effective in separating fiber from two commercial samples of DDGS (DDGS 1 and DDGS 2). Separation of fiber decreased the quantity of DDGS, but increased the value of DDGS by increasing protein content and produced a new coproduct with higher fiber content. Economic analysis was conducted to determine the payback period of the elusieve process. The dependence of feed prices on their protein content was determined. Equipment prices were obtained from industrial manufacturers. Relative to crude protein content of original DDGS, crude protein content of enhanced DDGS was higher by 8.5% for DDGS-1 and by 7.0% for DDGS-2. For a dry grind plant processing corn at the rate of 2,030 metric tonnes/day (80,000 bushels/day), increase in revenue due to the elusieve process would be $0.9 to 1.4M/year. Total capital investment for the elusieve process would be $1.4M and operating cost would be $0.1M/year. Based on these estimates, the payback period would be 1.1 to 1.7 years.