Enhanced ethanol production: In-situ ethanol extraction using selective adsorption

Abstract

In order to produce ethanol derived from lignocellulosic feeds at a cost that is competitive with current gasoline prices, the fermentation process, converting sugars to produce ethanol and the subsequent purification steps, must be enhanced. Due to their comparatively lower costs, the widespread availability across a range of climates, and their status as a dedicated energy crop, lignocellulosic biomass feeds are ideal raw materials that can be used to produce domestic fuels to partly displace our dependence on non-renewable sources. Currently, a major drawback of the technology is the relatively low ethanol tolerance of the micro-organisms used to ferment xylose and glucose.

To alleviate the ethanol inhibition of Escherichia coli KO11 (ATCC 55124) during fermentation, online ethanol sequestration was achieved through the implementation of an externally located packed bed adsorber for the purpose of on-line ethanol removal (using F-600 activated carbon).

By removing ethanol from the broth during the fermentation, inhibition due to the presence of ethanol could be alleviated, enhancing the substrate utilization and fermentation rate and the ethanol production of the fermentation.

This study details a comprehensive adsorbent screening to identify ethanol selective materials, modelling of multi-component adsorption systems, and the design, implementation and modelling of a fermentation unit coupled with an externally located packed bed adsorber.