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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Ph on Fouling Charateristics and Deposit Compositions in Dry Grind Thin Stillage

Authors
item Wilkins, Mark
item Buriak, Philip - UNIC OF IL, GRAD STUDENT
item Wallig, Matthew - UNIV OF IL
item Belyea, Ronald - UNIV OF MISSOURI
item Singh, Vijay - UNIV OF IL, GRAD STUDENT
item Tumbleson, M - UNIV OF IL
item Rausch, Kent - UNIV OF IL

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 1, 2006
Publication Date: February 15, 2006
Citation: Wilkins, M.R., Singh, V., Buriak, P., Belyea R.L., Wallig, M.A., Tumbleson, M.E., Rausch, K.D. 2006. Effect of ph on fouling charateristics and deposit compositions in dry grind thin stillage. Cereal Chemistry. 83:311-314.

Interpretive Summary: Demand for fuel ethanol has increased in recent years as the use of methyltertbutylether (MTBE) as a fuel oxygenate has been discontinued for environmental reasons. As a result, numerous dry grind corn (DGC) processing facilities have been constructed to produce ethanol from corn starch. DGC facilities produce ethanol, CO2 and distillers dried grains with solubles (DDGS), an animal food. To produce DDGS, DGC processors condense thin stillage, which contains solubles not converted to ethanol in fermentation, in evaporators. Thin stillage evaporators collect deposits on their surfaces in a process known as fouling. Fouling deposits must be removed from evaporators periodically to maintain maximum efficiency. Deposit cleaning costs processors time and money through cleaning costs and lost production time. This study evaluated how pH affects fouling deposit formation. Three batches of thin stillage were collected from a DGC facility. Tests were conducted at pH 3.5, 4.0 or 4.5, which represents the normal range of thin stillage pH. An annular fouling probe was used to measure fouling rates. Fouling occured at a faster rate at pH 3.5 than at 4.0 and 4.5. Protein contents of fouling deposits decreased and ash contents of fouling deposits increased as pH increased.

Technical Abstract: Demand for fuel ethanol has increased in recent years as the use of methyltertbutylether (MTBE) as a fuel oxygenate has been discontinued for environmental reasons. As a result, numerous dry grind corn (DGC) processing facilities have been constructed to produce ethanol from corn starch. DGC facilities produce ethanol, CO2 and distillers dried grains with solubles (DDGS), an animal food. To produce DDGS, DGC processors condense thin stillage, which contains solubles not converted to ethanol in fermentation, in multi effect evaporators. Thin stillage evaporators collect deposits on their surfaces in a process known as fouling. This study evaluated how thin stillage pH affected fouling using an annular fouling probe. Fouling tests were conducted at pH of 3.5, 4.0 and 4.5. Induction periods were shorter at pH 3.5 than at pH 4.0 and 4.5. Protein contents of fouling deposits decreased and ash contents of fouling deposits increased as pH increased. Phosphorus was the most abundant mineral element in fouling deposits.

Last Modified: 8/19/2014
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