Volatile fatty acid fermentation of biomass and kinetic modeling using the CPDM method /
This dissertation introduces, derives, and develops the Continuum Particle Distribution Modeling (CPDM) method of analyzing solid/fluid reaction systems. CPDM employs a particle conversion distribution function allowing a conversion-parameterized rate expression to be used. This approach is fundam...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739668311&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | This dissertation introduces, derives, and develops the Continuum Particle Distribution Modeling (CPDM) method of analyzing solid/fluid reaction systems. CPDM employs a particle conversion distribution function allowing a conversion-parameterized rate expression to be used. This approach is fundamentally different from the conventional Residence Time Distribution (RTD) method that is time parameterized. CPDM employs governing differential equations for the conversion distribution function; these are derived for various reactor configurations (batch, fed batch, continuous stirred tank reactor (CSTR), plug flow reactor (PFR), cascade CSTR, PFR-CSTR, CSTR-PFR. To demonstrate CPDM, the method was applied to simultaneous saccharification/fermentation (SSF) data from the literature in which dilute-acid treated aspenwood was converted to ethanol. For batch reactors, a hydrolysis rate model was developed with three adjustable parameters in addition to parameters taken from other literature sources. Using CPDM, this same rate model was applied to experimental CSTR data and predicted performance over a wide range of conditions with an average error in conversion of 4.4%. Volatile fatty acid (VFA) fermentations using a mixed culture of acid-forming microorganisms were modeled with CPDM including batch, fed-batch, and CSTR reactor configurations. The CSTR required a novel slurry feed delivery system. CPDM was able to describe the batch reactor performance and predict the CSTR product concentration with an average error of 0.63 g/L (9.6%). A continuous countercurrent reactor system employing bagasse/alfalfa as a feed was operated to study a countercurrent cascade CSTR. High conversions (>40%) and high VFA concentrations (>35 g/L) were obtained. Several other exploratory batch fermentations were performed to test various substrate/medium systems such as synthetic municipal solid waste and sewage sludge. Using CPDM, low pH (-5.8) was shown to inhibit fermentation most severely at high VFA concentrations and low conversions. Increasing nutrient concentration enhanced the fermentation rate by a factor of 20 at certain conditions. Pretreatment of the substrate (rye grass) with lime dramatically enhanced the fermentation rate (20x) at high conversion and low VFA concentration. CPDM is a powerful tool that can be used to compare different fermentation conditions. |
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| Item Description: | Vita. "Major Subject: Chemical Engineering". |
| Physical Description: | xx, 319 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 174-178. |