You are here:
Application of membrane processes to alcohol-water separation: Improving the energy efficiency of biofuel production(Singapore)
VANE, L. M. Application of membrane processes to alcohol-water separation: Improving the energy efficiency of biofuel production(Singapore). Presented at National University of Singapore Nanoscience & Nanotechnology Initiative, Singapore, SINGAPORE, January 25 - 29, 2010.
To inform the public
The prospect of dwindling oil supplies, concern over the carbon balance of the planet, and the availability of waste and non-waste biomass materials has generated renewed interest in the use of fermentation processes to produce commodity chemicals and fuels. The economics of fermentative production of fuels and chemicals can be a strong function of the efficiency with which the fermentation products are removed from the biological media. Due to growth inhibition by some fermentation products, including ethanol and butanol, concentrations of these products in fermentors are generally on the order of 1 to 10 percent by weight. These low concentrations greatly increase product recovery costs using traditional separation processes, such as distillation. Furthermore, the removal of trace water from the fermentation products to meet commercial specifications may require relatively large amounts of energy. Although several separation technologies are technically capable of removing volatile products from fermentation broths, distillation remains the dominant technology. Membrane-based pervaporation and vapor permeation have been proposed as energy saving alternatives to traditional technologies, especially for smaller systems. In pervaporation, compounds in the liquid feed permeate through a nonporous or molecularly porous membrane, and evaporate into a vapor permeate stream. In vapor permeation, the feed is a vapor stream. Otherwise, pervaporation and vapor permeation operate on similar principles. The properties of the membrane dictate the separation. For example, an organic stream can be dehydrated through the use of a hydrophilic membrane. Alternatively, if a hydrophobic membrane is used, organic compounds will preferentially pass through the membrane and a purified water stream will be retained by the membrane. Options for integrating pervaporation and vapor permeation systems with fermentation processes and the state-of-the-art of these membrane systems for this application will be discussed.