Ultrafiltration of Thin Stillage from Conventional and E-Mill Dry Grind Processes
- 186 Downloads
We used ultrafiltration (UF) to evaluate membrane filtration characteristics of thin stillage and determine solids and nutrient compositions of filtered streams. To obtain thin stillage, corn was fermented using laboratory methods. UF experiments were conducted in batch mode under constant temperature and flow rate conditions. Two regenerated cellulose membranes (10 and 100 kDa molecular weight cutoffs) were evaluated with the objective of retaining solids as well as maximizing permeate flux. Optimum pressures for 10 and 100 kDa membranes were 207 and 69 kPa, respectively. Total solids, ash, and neutral detergent fiber contents of input TS streams of dry grind and E-Mill processes were similar; however, fat and protein contents were different (p < 0.05). Retentate obtained from conventional thin stillage fractionation had higher mean total solids contents (27.6% to 27.8%) compared to E-Mill (22.2% to 23.4%). Total solids in retentate streams were found similar to those from commercial evaporators used in industry (25% to 35% total solids). Fat contents of retentate streams ranged from 16.3% to 17.5% for the conventional process. A 2% increment in fat concentration was observed in the E-Mill retentate stream. Thin stillage ash content was reduced 60% in retentate streams.
KeywordsBiofuels Membrane filtration Nutrient separation Ethanol
- 2.RFA (2009) Industry statistics. Renewable Fuels Association, Washington, DC. Available from: www.ethanolrfa.org/industry/statistics.
- 8.Meredith, J., Jacques, K. A., Lyons, T. P., & Kelsall, D. R. (2003). The alcohol textbook (pp. 355–361). Nottingham: Nottingham University Press.Google Scholar
- 10.Wu, Y. V., Sexson, K. R., & Wall, J. S. (1983). Reverse-osmosis of soluble fraction of corn stillage. Cereal Chemistry, 60, 248–251.Google Scholar
- 16.AACC International. (2000). Approved methods of the American Association of Cereal Chemists, 44-15A, 44-19 (10th ed.). St Paul: AACC International.Google Scholar
- 18.Zeman, L. J., & Zydney, A. L. (1996). Microfiltration and ultrafiltration: Principles and applications. New York: Marcel Dekker.Google Scholar
- 19.AOAC. (2003). Official methods of the AOAC. Methods 920.39, 942.05, 990.03 (17th ed.). Gaithersburg: The Association of Official Analytical Chemists.Google Scholar
- 20.SAS. (1989). SAS user’s guide: Statistics (5th ed.). Cary: SAS Institute.Google Scholar