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Membrane Filtration of Corn Steep Water

¹Agricultural Bioprocess Laboratory, University of Illinois, 1302 West Pennsylvania Avenue, Urbana, IL 61801. ²Present address: Novo Nordisk BioChem North America, Inc., Franklinton, NC. ³Corresponding author. E-mail: mcheryan@uiuc.edu Phone: 217-333-9332. Fax: 217-333-9592.

Membrane filtration is a cost-effective alternative to heat pasteurization of corn steep water. Trials were done in an operating ethanol plant with commercial spiral-wound modules. Flux increased with transmembrane pressure and became independent of pressure at >10 psi (69 kPa) with flux being higher at higher cross-flow velocities. Average flux at 4× concentration factor over 24-hr operating cycles was 34 L/m²/hr under optimum conditions. Capital cost of the membrane system is expected to be lower because it eliminates the heat pasteurizer and centrifuge and reduces cooling requirements. Operating cost of the microfilter are about one-third of a heat pasteurization system and provides the opportunity to recover insoluble protein and starch for use in corn gluten feed. Microfiltered steep water could improve ethanol fermentation efficiency and reduce fouling of heat exchangers in the fermenters, beer still, and steep evaporators.