Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Several steps during bioethanol processing are costly, including the enzymes. It is therefore of interest to develop enzymes, which can withstand the chemical and physical factors influencing their activity and stability during the processing of lignocellulosic materials into ethanol, and hence facilitate the possibility of recycling them to reduce costs. One of the challenges during enzyme recycling is the distillation, where the increased temperatures would eventually result in severe loss of enzyme activity. Examples of distillation systems operating at lower temperatures are now available, which increase the possibilities for recycling. However, these systems may have other challenges such as mechanical forces, which may lead to inactivation of the enzymes. There is a growing interest for thermostable enzymes since they can handle increased temperatures in distillation, but also are known to be more stable and inhibitor tolerant. Applying thermostable enzymes would enable more efficient recycling since these enzymes will not be inactivated in the same way as mesophilic enzymes.
The purpose of this study was to investigate the stability and activity of two enzyme preparations (mesophilic and thermostable) when exposed to increasing temperatures and mechanical forces during distillation. The studies were mainly made in stillage cotaining high levels of lignin, but were also tested in non-lignin media. The influence of mechanical force and thermodynamic heat transfer (converting liquid to steam) were tested in a pilot distillation facility. The results can be used for more efficient design of process equipment with focus on enzyme recycling.