Membrane separation of ethanol/water mixtures by film vaporization to be coupled with fermentation unit

Production of bioethanol as fuel from renewable sources constitutes various sub-systems such as raw material treatment, fermentation, and alcohol separation from the fermentation broth. The conventional distillation of the fermentation broth is the most costly part of the complete procedure. This makes the production of biofuels uneconomic compared to fossil fuels. Separation carried out by membranes is considered to be one of the most promising process for energy saving separation technology. We studied the separation of ethanol by film vaporization on membrane to determine the optimum operational conditions so that the fermentation efficiency will be enhanced as much as the product ethanol is removed in case of coupling. In this separation method, the application of a partial vacuum pressure on the permeate side induces partial vaporization of ethanol on the liquid film of a microfiltration membrane sur face. Investigations focused on the effects of temperature, permeate side pressure and the ethanol feed concentration. An increase in the temperature increased the ethanol flux but decreased the separation factor. As the permeate side pressure was increased, the separation factor also increased while the ethanol flux decreased. At a well specified permeate side pressure, the separation factor changed inversely with the ethanol feed concentration.