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Modelling and Optimisation of Integrated Biotechnical Processes -Application to the Fermentative Production of Lactic Acid from Wheat Flour

Åkerberg, Christina LU (2000)
Abstract (Swedish)
Popular Abstract in Swedish

I den här doktorsavhandlingen presenteras ett datorprogram som utvecklats för att simulera och utvärdera biotekniska processer, där flera processteg kan vara integrerade. Speciellt har en process för framställning av mjölksyra från vetemjöl studerats. Mjölksyra har traditionellt använts i kemi-, läkemedels- och livsmedelsindustrin som t.ex. råvara, surgörare eller konserveringsmedel. Mjölksyraframställning har på senare tid också rönt stort intresse eftersom mjölksyra kan användas för att tillverka en biologiskt nedbrytningsbar plast polymjölksyra. Polymjölksyra kan användas inom det medicinska området för att tillverka suturtrådar och implantat som bryts ned automatiskt och för läkemedel där man... (More)
Popular Abstract in Swedish

I den här doktorsavhandlingen presenteras ett datorprogram som utvecklats för att simulera och utvärdera biotekniska processer, där flera processteg kan vara integrerade. Speciellt har en process för framställning av mjölksyra från vetemjöl studerats. Mjölksyra har traditionellt använts i kemi-, läkemedels- och livsmedelsindustrin som t.ex. råvara, surgörare eller konserveringsmedel. Mjölksyraframställning har på senare tid också rönt stort intresse eftersom mjölksyra kan användas för att tillverka en biologiskt nedbrytningsbar plast polymjölksyra. Polymjölksyra kan användas inom det medicinska området för att tillverka suturtrådar och implantat som bryts ned automatiskt och för läkemedel där man vill kontrollera nedbrytningshastigheten. Plasten kan också användas som förpackningsmaterial.



I processen som presenteras i den här doktorsavhandlingen, har vetemjöl använts som råvara för mjölksyratillverkningen. Vetemjölet innehåller stärkelse som kan brytas ned till socker med hjälp av enzymer. Mjölksyrabakterier kan sedan omvandla sockret till mjölksyra som därefter separeras och renas upp. För att förbättra processen så att bakterierna och enzymerna arbetar så effektivt som möjligt och för att minska tillverkningskostnaden, kan flera processteg integreras. En sådan process är komplex och det är svårt att förutsäga hur processen ska se ut för att arbeta optimalt. Därför har ett datorprogram, BioProcSim, utvecklats som underlättar beräkningar av sådana komplexa processer. Datorprogrammet har använts för att matematiskt beskriva nedbrytning av stärkelse samt omvandling av socker till mjölksyra. Det har också använts för att göra en ekonomisk utvärdering av den totala mjölksyraprocessen, jämföra flera processkonfigurationer och slutligen hitta det alternativ som ger den lägsta produktionskostnaden för mjölksyra. (Less)
Abstract
Biotechnical processes are often integrated to increase productivity and yield. It is difficult to predict the effects of process integration and to find optimum conditions for the process. A valuable tool for the evaluation of a complete process is mathematical modelling. In this thesis, a computer program developed for simulation and optimisation of integrated biotechnical processes is presented. The computer program can be used for simulation, parameter fitting, optimisation, economical evaluation and Monte Carlo simulation.



The computer program has been used to evaluate a process for the fermentative production of lactic acid from wheat flour. In this process, wheat starch is hydrolysed to glucose in two steps:... (More)
Biotechnical processes are often integrated to increase productivity and yield. It is difficult to predict the effects of process integration and to find optimum conditions for the process. A valuable tool for the evaluation of a complete process is mathematical modelling. In this thesis, a computer program developed for simulation and optimisation of integrated biotechnical processes is presented. The computer program can be used for simulation, parameter fitting, optimisation, economical evaluation and Monte Carlo simulation.



The computer program has been used to evaluate a process for the fermentative production of lactic acid from wheat flour. In this process, wheat starch is hydrolysed to glucose in two steps: liquefaction and saccharification. The glucose is fermented to lactic acid by lactic acid bacteria, using components from the wheat flour as nutrients. Fermentation is performed at a pH higher than the pKa for lactic acid and the end product of the fermentation step is thus mainly lactate. In the downstream processing the lactate is separated from cells and wheat flour particles using centrifugation and membrane techniques. The lactate is converted to lactic acid by electrodialysis and is concentrated by evaporation.



The work presented in this thesis comprises the development of kinetic models for the saccharification of wheat starch and for the fermentation of glucose to lactic acid. The computer program has been used to determine the values of the parameter in the kinetic models, using experimental data. These models have been used to study the integration of the saccharification and fermentation steps. The computer program has also been used to perform an economical evaluation of the entire process for the production of lactic acid with a concentration of 70 wt-%. A number of process configurations have been suggested and compared, and the optimal wheat flour concentration has been determined. To investigate the influence of variations in operational and investment costs on the lactic acid production cost, a Monte Carlo simulation has been performed. (Less)
Please use this url to cite or link to this publication:
author
opponent
  • Professor Heinzle, Elmar, Biochemical Engineering, Universität des Saarlandes, Tyskland
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Chemical technology and engineering, economy, wheat flour, starch, lactic acid, kinetics, simulation, modelling, optimisation, Kemiteknik och kemisk teknologi
pages
60 pages
publisher
Prof. Guido Zacchi, Deparment of Chemical Engineering 1, Chemical Center, Lund University
defense location
Lecture Hall C, Chemical Center, Getingevägen 60, Lund
defense date
2000-06-09 10:15
external identifiers
  • other:ISRN: LUTKDH/TKKA-1003/1-60/(2000)
ISSN
1100-2778
ISBN
91-7874-045-2
language
English
LU publication?
yes
id
6dc42223-a5c1-46fc-aebd-6ee38031d54c (old id 40641)
date added to LUP
2007-10-13 13:48:51
date last changed
2016-09-19 08:44:53
@phdthesis{6dc42223-a5c1-46fc-aebd-6ee38031d54c,
  abstract     = {Biotechnical processes are often integrated to increase productivity and yield. It is difficult to predict the effects of process integration and to find optimum conditions for the process. A valuable tool for the evaluation of a complete process is mathematical modelling. In this thesis, a computer program developed for simulation and optimisation of integrated biotechnical processes is presented. The computer program can be used for simulation, parameter fitting, optimisation, economical evaluation and Monte Carlo simulation.<br/><br>
<br/><br>
The computer program has been used to evaluate a process for the fermentative production of lactic acid from wheat flour. In this process, wheat starch is hydrolysed to glucose in two steps: liquefaction and saccharification. The glucose is fermented to lactic acid by lactic acid bacteria, using components from the wheat flour as nutrients. Fermentation is performed at a pH higher than the pKa for lactic acid and the end product of the fermentation step is thus mainly lactate. In the downstream processing the lactate is separated from cells and wheat flour particles using centrifugation and membrane techniques. The lactate is converted to lactic acid by electrodialysis and is concentrated by evaporation.<br/><br>
<br/><br>
The work presented in this thesis comprises the development of kinetic models for the saccharification of wheat starch and for the fermentation of glucose to lactic acid. The computer program has been used to determine the values of the parameter in the kinetic models, using experimental data. These models have been used to study the integration of the saccharification and fermentation steps. The computer program has also been used to perform an economical evaluation of the entire process for the production of lactic acid with a concentration of 70 wt-%. A number of process configurations have been suggested and compared, and the optimal wheat flour concentration has been determined. To investigate the influence of variations in operational and investment costs on the lactic acid production cost, a Monte Carlo simulation has been performed.},
  author       = {Åkerberg, Christina},
  isbn         = {91-7874-045-2},
  issn         = {1100-2778},
  keyword      = {Chemical technology and engineering,economy,wheat flour,starch,lactic acid,kinetics,simulation,modelling,optimisation,Kemiteknik och kemisk teknologi},
  language     = {eng},
  pages        = {60},
  publisher    = {Prof. Guido Zacchi, Deparment of Chemical Engineering 1, Chemical Center, Lund University},
  school       = {Lund University},
  title        = {Modelling and Optimisation of Integrated Biotechnical Processes -Application to the Fermentative Production of Lactic Acid from Wheat Flour},
  year         = {2000},
}