375 Fouling tendencies of corn wet milling steepwater subjected to membrane filtration processing.

S. R. ECKHOFF (1), M. Kakleas (1), V. Singh (1), R. Simms (2), C. B. Panchal (3), and K. D. Rausch (1). (1) Department of Agricultural Engineering, University of Illinois, Urbana, IL 6180; (2) Technology, Inc., Fort Smith, AR 72916; (3) Agronne National Lab, 9700 South Cass Avenue, Argonne, IL 60439.

In the wet milling process, concentration of steepwater in multi-effect evaporators is a capital- and energy-intensive unit operation. Additional costs in evaporator operation are incurred when the evaporator sustains buildup of proteinaceous materials, called fouling, which eventually results in evaporator down time. Maintenance work on the evaporators results in labor costs and reduced capacity of the facility. An annular fouling probe was used to measure the relative fouling tendencies of light steepwater from a commercial wet milling facility. This probe measures the rate of heat transfer through a surface, allowing the determination of the change in fouling resistance due to the buildup. Using stainless steel microfiltration membranes, light steepwater was filtered in a pilot scale feed-and-bleed system located at a wet milling facility. Samples of membrane permeate (filtered material) and concentrate were used in the fouling probe system to measure fouling tendencies and compared to unfiltered light steepwater. Benefits of passing steepwater through a microfiltration membrane prior to evaporator concentration to reduce fouling will be discussed.