A review of pervaporation for product recovery from biomass fermentation processes

Abstract

Although several separation technologies are technically capable of removing volatile products from fermentation broths, distillation remains the dominant technology. This is especially true for the recovery of biofuels such as ethanol. In this paper, the status of an emerging membrane-based technology, called pervaporation, for this application is reviewed. Several issues and research priorities which will impact the ability of pervaporation to be competitive for biofuel recovery from fermentation systems are identified and discussed. They include: increased energy efficiency; reduction of capital cost for pervaporation systems; longer term trials with actual fermentation broths; optimized integration of pervaporation with fermentor; synergy of performing both alcohol recovery and solvent dehydration by pervaporation with dephlegmation fractional condensation technology; and updated economic analyses of pervaporation at various biofuel production scales. Pervaporation is currently viable for biofuel recovery in a number of situations, but more widespread application will be possible when progress has been made on these issues.

Influence of fermentation by-products on the purification of ethanol from water using pervaporation

“…The production of fuel grade ethanol (>99.5 wt.%) from a raw feedstock is schematically depicted in Fig. 1 and involves four major steps, although some steps are sometimes redundant or can be combined (Balat et al, 2008;Vane, 2005).…”

“…Since the first step in a bio-ethanol production process involves the conversion of a feedstock into simple sugars, sugars will always be present during a coupled fermentation-pervaporation process. Glycerol and succinic acid can be present in the fermentation mixture up to 0.8 and 0.4 wt.%, respectively, while concentrations of other carboxylic acids and diols are maximally 0.1 wt.% (Maiorella, 1983;Vane, 2005). Salts are often added to a fermentation broth to act as a nitrogen or mineral source for microorganisms, and concentrations typically range between 1 and 10 g/l (Lin and Tanaka, 2006).…”

Pervaporation of methanol from methylacetate mixture using polyamide-6 membrane

“…Although the pervaporation mechanism can be explained in different ways [5,6], most researchers are in agreement with the transport of the vapor through a non-porous (dense) film involving three successive steps (solution-diffusion mechanism) as follows [7,8]:…”

“…Pervaporation (PV) process is considered an economic alternative in terms of energy consumption [1,2], and has a high separation efficiency of azeotropic mixtures, close-boiling point compounds, and isomeric or heat-sensitive liquid mixtures [3][4][5][6][7]. A feed mixture contacts one side of a non-porous permselective membrane; the permeate is removed as a vapor from the other side.…”

“…The recent researches revealed that the separation of methyl acetate-methanol azeotrope can occur in a reactive distillation column, but the refined methyl acetate cannot be obtained in the primary reactive distillation column, and a secondary column is required to break up methyl acetate from methyl acetate-methanol azeotrope [3][4][5][6]. Further problems are created in commercial processes by the presence of impurities in the methanol and acetic acid feedstocks.…”