Computer-based studies on bioprocess engineering : II - Tools for process operation

In this paper we review recent advances on the practice and theory of process control with particular emphasis to the operation of bioreactors. We present in detail a case-study on the modelling, model-based identification and adaptive control of fed-batch baker's yeast fermentation.Junta Nacional de Investigação Científica e Tecnológica (JNICT) - contract numbers BD/224/90-IF, BD/1476/91-RM.Instituto Nacional de Investigação Científica (INIC)

Takagi-Sugeno fuzzy observer for a switching bioprocess : sector nonlinearity approach

Mexican Consejo Nacional de Ciencia y Tecnología (CONACyT)

Adding Value to Lignocellulosic Biorefinery: Efficient Process Development of Lignocellulosic Biomass Conversion into Polyhydroxybutyrate

Polyhydroxybutyrate (PHB) is bacteria synthesized polymer that has comparable mechanical properties as petroleum-based plastics and high biocompatibility. Current commercial PHB production process is not cost effective. Raw materials make up about 50% of the production cost. Lignocellulosic biomass are cheap, abundant feedstocks that can be converted into PHB to add profit and sustainability to lignocellulosic biorefinery. Lignocellulosic biorefinery upstream process produces polymeric sugar rich stream and lignin-enriched stream. Polymeric sugars are then hydrolyzed into a sugar stream with glucose, xyloseand arabinose mainly present. To the best of the author’s knowledge, limited studies have been done on sugar mixture conversion into PHB. For lignin, previous research achieved a PHB production ranging from 0.13 to 1 g/L, which is too low to be economical. The primary objectives of this research were twofold: (1) process development of polymeric sugars conversion into PHB, with a focus on sugar mixture conversion into PHB by Burkholderia sacchari DSM 17165, and (2) process development of lignin into PHB by Cupriavidus necator DSM 545, with a focus on enhancing PHB production using various types of supplements. For sugar mixture conversion into PHB, first, shake flask (250 mL) scale statistical experimental design and modeling were performed to optimize sugar mixture ratio and process variables for maximal PHB production; second, bioreactor scale (3L) fed-batch cultivation was conducted to produce PHB from simulated corn fiber sugar mixture. The highest PHB production reached 67 g/L for 4:2:1 (glucose:xylose:arabinose) mixture at 41 h corresponding to an accumulation of 77% of cell dry weight. Corresponding sugar conversion efficiency and productivity were 0.33 g PHB/g sugar consumed and 1.6 g/L/h, respectively, which are comparable to or higher than most previous studies. For lignin conversion into PHB, first, shake scale (250 mL) study achieved 10-fold increase (0.2 to 2.1 g/L) in PHB production by optimizing supplement formulations with Plackett-Burman and central composite designs. Second, fed-batch cultivation at bioreactor scale (1.7 L) were conducted to enhance PHB production to 4.5 g/L. This is the highest PHB production from lignin that the author has been aware of in the literature. Advisor: Mark R. Wilkin

Adding Value to Lignocellulosic Biorefinery: Efficient Process Development of Lignocellulosic Biomass Conversion into Polyhydroxybutyrate

Polyhydroxybutyrate (PHB) is bacteria synthesized polymer that has comparable mechanical properties as petroleum-based plastics and high biocompatibility. Current commercial PHB production process is not cost effective. Raw materials make up about 50% of the production cost. Lignocellulosic biomass are cheap, abundant feedstocks that can be converted into PHB to add profit and sustainability to lignocellulosic biorefinery. Lignocellulosic biorefinery upstream process produces polymeric sugar rich stream and lignin-enriched stream. Polymeric sugars are then hydrolyzed into a sugar stream with glucose, xyloseand arabinose mainly present. To the best of the author’s knowledge, limited studies have been done on sugar mixture conversion into PHB. For lignin, previous research achieved a PHB production ranging from 0.13 to 1 g/L, which is too low to be economical. The primary objectives of this research were twofold: (1) process development of polymeric sugars conversion into PHB, with a focus on sugar mixture conversion into PHB by Burkholderia sacchari DSM 17165, and (2) process development of lignin into PHB by Cupriavidus necator DSM 545, with a focus on enhancing PHB production using various types of supplements. For sugar mixture conversion into PHB, first, shake flask (250 mL) scale statistical experimental design and modeling were performed to optimize sugar mixture ratio and process variables for maximal PHB production; second, bioreactor scale (3L) fed-batch cultivation was conducted to produce PHB from simulated corn fiber sugar mixture. The highest PHB production reached 67 g/L for 4:2:1 (glucose:xylose:arabinose) mixture at 41 h corresponding to an accumulation of 77% of cell dry weight. Corresponding sugar conversion efficiency and productivity were 0.33 g PHB/g sugar consumed and 1.6 g/L/h, respectively, which are comparable to or higher than most previous studies. For lignin conversion into PHB, first, shake scale (250 mL) study achieved 10-fold increase (0.2 to 2.1 g/L) in PHB production by optimizing supplement formulations with Plackett-Burman and central composite designs. Second, fed-batch cultivation at bioreactor scale (1.7 L) were conducted to enhance PHB production to 4.5 g/L. This is the highest PHB production from lignin that the author has been aware of in the literature. Advisor: Mark R. Wilkin

Hydrogen production from glucose by inhibiting hydrogenotrophic methanogens carbon-18 long-chain fatty acids.

Dark fermentation is an attractive process for hydrogen (H2) production from organic substrates. Rapid conversion of H2 to other products, particularly methane, is a major hindrance to H2 accumulation and recovery from the process. Long chain fatty acids (LCFAs) namely oleic (C18:0) acid (OA) and linoleic (C18:1) acid are inhibitors of aceticlastic methanogens and are suspected inhibitors of hydrogenotrophic methanogens. However, the effect of such inhibition on increasing H2 recovery from organic substrates has not been examined. Hence, in this study, C18 LCFAs were used to increase the quantity of H2 from glucose degradation. Batch experiments were conducted at 23 +/- 2°C to examine the effect of LCFA concentration (0 to 2,000 mg 1-1) and the initial pH (pH 5, 6 and 7.8) on the fermentative H2 production. Glucose was re-injected on day 4 or day 5 to examine the combined effect of LCFA, volatile fatty acids (VFAs) and intermittent sparging on H2 production. H2 production was a function of LCFA concentration and the initial pH. The maximum H2 yield recorded was approximately 2.7 mol H2·mol-1 glucose in cultures receiving LA at an initial pH of 6. Glucose degradation was inhibited in cultures receiving LCFA. Inhibition of glucose degradation was enhanced at lower initial pH values. Overall, the data demonstrated that LA and OA can be used to enhance H 2 accumulation and recovery from organic substrates.Dept. of Civil and Environmental Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis2005 .G87. Source: Masters Abstracts International, Volume: 44-03, page: 1472. Thesis (M.A.Sc.)--University of Windsor (Canada), 2005

An illustrative analysis of atypical gas production profiles obtained from in vitro digestibility studies using fecal inoculum

14 páginas, 2 tablas, 6 figuras.Gas production profiles typically show a monotonically increasing monophasic pattern. However, atypical gas production profiles exist whereby at least two consecutive phases of gas production or additional extraneous features that distort the typical profile are present. Such profiles are more likely to occur with the use of a fecal inoculum and are much less well described. The presence of multiple phases or non-descript extraneous features makes it difficult to apply directly recommended modeling approaches such as standard response functions or classical growth functions. To overcome such difficulties, extensions of the Mitscherlich equation and a numerical modeling option also based on the Mitscherlich are explored. The numerical modeling option uses an estimate of relative rate obtained from the smoothed data profile and an estimate of maximum gas produced together with any lag time information drawn from the raw data to construct a simple Mitscherlich equation. In summary, this article illustrates the analysis of atypical gas production profiles obtained using a fecal inoculum and explores the methodology of numerical modeling to reconstruct equivalent typical growth-like trends.This research was funded in part by The Canada Research Chairs program, grant number 045867 (Natural Sciences and Engineering Research Council of Canada, Ottawa)