Product Drying, Energy Use and Pollution Control

Proper operation of a wet-milling system requires the use of 1420-1830 L of fresh water per metric ton of corn (15-22 gal per 1001b), all added at the final hydroclone stage. This water must eventually be removed from the products by evaporation, since most wet-milled products are marketed at 10-12% moisture content. 

For many years the control of air and water pollution from biodegradable streams and streams which contain hazardous chemical residues, as well as recovery of unaccounted dry substance, has been a major concern for the wet-milling industry. These problems have been reduced gradually by the development of new by-products and by treatment of wastewater streams, so that they may be returned to the process, put into community sewers or sent to dedicated waste treatment facilities. In the 1930s, the practice of disposing of steepwater and unwanted process water in waterways was stopped, resulting in the development of the bottled up process.5,223 

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