Category Archives: PROCESS SYNTHESIS. FOR FUEL ETHANOL. PRODUCTION

ANALYSIS OF FED-BATCH ETHANOLIC FERMENTATION

In Section 7.1.2.2., the principle and applications of fed-batch fermentation tech­nologies for ethanol production were discussed. The operation of fermenters under fed-batch conditions is very difficult to model due to the fact that micro­bial cells grow under permanently changing conditions including volume changes explained by feeding of fresh medium into the bioreactor (Cardona and Sanchez, 2007). To tackle this problem, […]

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Case Study. Development of a Short-Cut Method for Extractive Fermentation

One of the approaches highlighted in Chapter 2 for accomplishing process synthe­sis consists of the application of the principles of topologic thermodynamics (see Section 2.2.6). In the work mentioned above (Sanchez et al., 2006), a preliminary short-cut method to analyze the extractive co-fermentation was developed. In par­ticular, the main components (substrate-water-product-solvent) can be represented in a quaternary diagram in order […]

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ROLE OF ENERGY INTEGRATION DURING PROCESS SYNTHESIS

Described types of integration in Chapter 9 are related to the integration of mate­rial flows either for their transformation or for the separation of their components. Similarly, the energy integration of the different steps for ethanol production is possible. Energy integration, particularly heat integration, looks for the best utili­zation of energy flows (heat, mechanical, and electrical) generated or consumed inside […]

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Starch Sources for Ethanol Production

As the starch is a polymer exclusively composed of glucose residues, it has become a very important feedstock for ethanol production. For this, the breakdown of starch into glucose with the subsequent conversion of glucose into ethanol using appropriate fermenting microorganisms is required. The technologies for starch hydrolysis will be discussed in Chapter 5. The grains are the feedstock most […]

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Bacteria

Some bacteria have the capacity to produce ethanol in significant amounts mak­ing them potential microorganisms for industrial purposes (see Table 6.2). Among bacteria, the most promising microorganism is Zymomonas mobilis. This facul­tative anaerobe presents higher ethanol yields than yeasts, which is related to the metabolic pathways involved. Z. mobilis makes use of the Entner-Doudoroff pathway converting 1 mol of hexose […]

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EVALUATION OF SEPARATION AND DEHYDRATION SCHEMES

For process synthesis procedures intended for the design of fuel ethanol pro­duction processes, the selection of the technological scheme for ethanol separa­tion and dehydration has paramount importance. Thus, the utilization of salts as extractive agents (saline extractive distillation) has demonstrated certain energetic advantages compared to other dehydration schemes, according to some reports (Barba et al., 1985; Llano-Restrepo and Aguilar-Arias, 2003). […]

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Wastewater Treatment of Biomass-to-Ethanol Process

In general, it is considered that the characteristics of the stillage produced from lignocellulosic materials are comparable to those of the stillage obtained when conventional feedstocks are employed, thus the treatment and utilization methods of this latter type of stillage can be applied to the lignocellulosic stillage (Wilkie et al., 2000). The flowsheets proposed for the treatment of the stillage […]

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