Stan Mayfield Biorefinery: update and current status

The Stan Mayfield Biorefinery is a facility managed by the University of Florida created with the purpose of scaling-up and assessing the production of lignocellulosic chemicals and fuels.  Here we have successfully scaled-up a liquefaction plus simultaneous saccharification and co-fermentation (L+SScF) process for lignocellulosic ethanol production. The plant was designed to handle different feedstocks and operate continuously processing between 3-5 tons of biomass per day.  Based on previous data obtained in the lab, the pretreatment technology selected consists of dilute phosphoric acid combined with steam explosion.  After most of the hemicellulose is solubilized during pretreatment, a continuous liquefaction with a 6-h retention time solubilizes the cellulose fraction, resulting in a pumpable slurry that has a high concentration of hemicellulose and cellulose sugars.  The biomass slurry is then temperature-and-pH-adjusted to the fermentation values and transferred into one of three 8000 gal (~30000 L) fermentors.  The fermentor is inoculated once the level in the fermentation tank reaches 15%, and it is continually fed until it has been completely filled.  The fermentation is completed within 48 h with almost total utilization of xylose and glucose by the engineered ethanologenic strain Escherichia coli SL100.  In this work we will be presenting the results obtained during the optimization of the process using sugarcane bagasse as feedstock.  Future work will include the use of other lignocellulosic materials, such as sorghum bagasse, in the process.