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Development of a large‐scale biocalorimeter to monitor and control bioprocesses
Author(s) -
Voisard D.,
Pugeaud P.,
Kumar A. R.,
Jenny K.,
Jayaraman K.,
Marison I. W.,
von Stockar U.
Publication year - 2002
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.10351
Subject(s) - calorimeter (particle physics) , calibration , bioreactor , process engineering , temperature control , scale up , instrumentation (computer programming) , scale (ratio) , environmental science , nuclear engineering , computer science , mechanical engineering , chemistry , engineering , electrical engineering , physics , organic chemistry , classical mechanics , quantum mechanics , detector , operating system
Abstract Calorimetry has shown real potential at bench‐scale for chemical and biochemical processes. The aim of this work was therefore to scale‐up the system by adaptation of a standard commercially available 300‐L pilot‐scale bioreactor. To achieve this, all heat flows entering or leaving the bioreactor were identified and the necessary instrumentation implemented to enable on‐line monitoring and dynamic heat balance estimation. Providing that the signals are sufficiently precise, such a heat balance would enable calculation of the heat released or taken up during an operational (bio)process. Two electrical Wattmeters were developed, the first for determination of the power consumption by the stirrer motor and the second for determination of the power released by an internal calibration heater. Experiments were designed to optimize the temperature controller of the bioreactor such that it was sufficiently rapid so as to enable the heat accumulation terms to be neglected. Further calibration experiments were designed to correlate the measured stirring power to frictional heat losses of the stirrer into the reaction mass. This allows the quantitative measurement of all background heat flows and the on‐line quantitative calculation of the (bio)process power. Three test fermentations were then performed with B. sphaericus 1593M, a spore‐forming bacterium pathogenic to mosquitoes. A first batch culture was performed on a complex medium, to enable optimization of the calorimeter system. A second batch culture, on defined medium containing three carbon sources, was used to show the fast, accurate response of the heat signal and the ability to perfectly monitor the different growth phases associated with growth on mixed substrates, in particular when carbon sources became depleted. A maximum heat output of 1100 W was measured at the end of the log‐phase. A fed‐batch culture on the same defined medium was then carried out with the feed rate controlled as a function of the calorimeter signal. A maximum heat output of 2250 W was measured at the end of the first log‐phase. This work demonstrates that real‐time quantitative calorimetry is not only possible at pilot‐scale, but could be readily applied at even larger scales. The technique requires simple, readily available devices for determination of the few necessary heat flows, making it a robust, cost‐effective technique for process development and routine monitoring and control of production processes. © 2002 Wiley Periodicals, Inc. Biotechnol Bioeng 80: 125–138, 2002