Effect of Control Flow Cavitation and Cellulose Hydrolysis on Commercial Scale Dry Mill Ethanol Yield

Abstract.

Dry mill corn ethanol production generates nearly 14 billion gal/yr of biofuel in the US representing nearly 10% of transportation fuel used. However, during this process as much as 5% of the starch remains unconverted after fermentation. In addition, the cellulose present in the grain is not converted by the enzymes used for starch hydrolysis. The objective of this study was to evaluate the effects of controlled flow cavitation and cellulase addition on ethanol yields at a commercial scale dry mill ethanol plant. Samples were collected at a 100 million gal/yr plant with a cavitation unit installed both before and after controlled flow cavitation but prior to liquefaction. Results showed that cavitation significantly increased DP4+, DP3 and total sugar concentrations by 2%, 6% and 3% (CI>98%), respectively, during liquefaction. Ethanol yields from cavitated fermented slurries were significantly greater (CI=99.8%) by 2.2% than yields from uncavitated samples. Uncavitated samples amended with cellulase also exhibited a significant increase in ethanol yield of 2.5% as compared to unamended, non-cavitated samples (CI=99.8). The greatest yield improvement of 4.1% (CI=99.9%) was observed in samples that were both cavitated and amended with cellulase enzymes. These results indicate that controlled flow cavitation and cellulase amendment could significantly improve the economics and resource use efficiency of bioethanol production at dry mill ethanol plants.