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Determination of growth and coupled nitrification/denitrification by immobilized Thiosphaera pantotropha using measurement and modeling of oxygen profiles

Hooijmans, C.M.; Geraats, S.G.M.; van Niel, Ed LU ; Robertson, L.A. ; Heijnen, J.J. and Luyben, K.Ch.A.M. (1990) In Biotechnology and Bioengineering 36. p.931-939
Abstract
An oxygen microsensor in combination with mathematical modeling was used to determine the behavior of immobilized Thiosphaera pantotropha. This organism can convert ammonia completely to nitrogen gas under aerobic conditions (coupled nitrification/denitrification) and denitrifies nitrate at highest rates under anaerobic conditions. Immobilization of T. pantotropha can result in aerobic and anaerobic zones inside the biocatalyst particle which will be advantageous for the conversion of ammonia and nitrate from wastewater. However, information of the effects of immobilization on the physiology of T. pantotropha is necessary for the development of such a system. This article gives the extension of a model developed to describe the behavior of... (More)
An oxygen microsensor in combination with mathematical modeling was used to determine the behavior of immobilized Thiosphaera pantotropha. This organism can convert ammonia completely to nitrogen gas under aerobic conditions (coupled nitrification/denitrification) and denitrifies nitrate at highest rates under anaerobic conditions. Immobilization of T. pantotropha can result in aerobic and anaerobic zones inside the biocatalyst particle which will be advantageous for the conversion of ammonia and nitrate from wastewater. However, information of the effects of immobilization on the physiology of T. pantotropha is necessary for the development of such a system. This article gives the extension of a model developed to describe the behavior of chemostat cultures of T. pantotropha so that it can be used for immobilized cells. The original model was based on metabolic reaction equations. Kinetic and diffusion equations have now been added. Experimental verification was carried out using a stirred tank reactor and a Kluyver flask. After immobilization in agarose, the cells were grown in the particles under continuous culture conditions for 3 days. After 24 h the oxygen penetration depth showed a constant value of 100 μ, indicating that a steady state was reached. Scanning electron micrographs showed that large colonies of cells were present in this 100-μm aerobic layer.

From the dynamics of the start-up phase, several parameters were determined from measurements of the oxygen concentration profiles made every few hours. The profiles simulated by the model were fitted to the measured data. The average value for the maximum specific growth rate was 0.52 h−1, and the maximum oxygen conversion rate was 1.0 mol Cmol−1 h−1. The maximum specific acetate uptake rate was 2.0 mol Cmol−1 h−1, and the Monod constant for acetate was 2.9 × 10−2 mol m−3. The maximum specific nitrification rate was 0.58 × 10−1 mol Cmol−1 h−1, and the amount of oxygen necessary for nitrification was 11% of the total oxygen uptake rate. Most of the kinetic parameters determined for the immobilized cells were in good agreement with those for the suspended cells. Only the maximum specific growth rate was significantly higher, and the maximum specific nitrification rate was some what lower than for suspended cells. The experimental results clearly show that an oxygen microsensor, in combination with mathematical modeling, can successfully be used to elucidate the kinetic behavior of immobilized, oxygen-consuming, cells.
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author
publishing date
type
Contribution to journal
publication status
published
keywords
nitrification, denitrification, Thiosphaera pantotropha, immobilization, oxygen profiles
in
Biotechnology and Bioengineering
volume
36
pages
9 pages
publisher
John Wiley & Sons
external identifiers
  • scopus:0025514224
ISSN
0006-3592
DOI
10.1002/bit.260360908
language
English
LU publication?
no
id
c781739d-65e0-4866-b390-49125e0adc39
date added to LUP
2016-08-26 13:16:02
date last changed
2017-09-03 05:11:41
@article{c781739d-65e0-4866-b390-49125e0adc39,
  abstract     = {An oxygen microsensor in combination with mathematical modeling was used to determine the behavior of immobilized Thiosphaera pantotropha. This organism can convert ammonia completely to nitrogen gas under aerobic conditions (coupled nitrification/denitrification) and denitrifies nitrate at highest rates under anaerobic conditions. Immobilization of T. pantotropha can result in aerobic and anaerobic zones inside the biocatalyst particle which will be advantageous for the conversion of ammonia and nitrate from wastewater. However, information of the effects of immobilization on the physiology of T. pantotropha is necessary for the development of such a system. This article gives the extension of a model developed to describe the behavior of chemostat cultures of T. pantotropha so that it can be used for immobilized cells. The original model was based on metabolic reaction equations. Kinetic and diffusion equations have now been added. Experimental verification was carried out using a stirred tank reactor and a Kluyver flask. After immobilization in agarose, the cells were grown in the particles under continuous culture conditions for 3 days. After 24 h the oxygen penetration depth showed a constant value of 100 μ, indicating that a steady state was reached. Scanning electron micrographs showed that large colonies of cells were present in this 100-μm aerobic layer.<br/><br/>From the dynamics of the start-up phase, several parameters were determined from measurements of the oxygen concentration profiles made every few hours. The profiles simulated by the model were fitted to the measured data. The average value for the maximum specific growth rate was 0.52 h−1, and the maximum oxygen conversion rate was 1.0 mol Cmol−1 h−1. The maximum specific acetate uptake rate was 2.0 mol Cmol−1 h−1, and the Monod constant for acetate was 2.9 × 10−2 mol m−3. The maximum specific nitrification rate was 0.58 × 10−1 mol Cmol−1 h−1, and the amount of oxygen necessary for nitrification was 11% of the total oxygen uptake rate. Most of the kinetic parameters determined for the immobilized cells were in good agreement with those for the suspended cells. Only the maximum specific growth rate was significantly higher, and the maximum specific nitrification rate was some what lower than for suspended cells. The experimental results clearly show that an oxygen microsensor, in combination with mathematical modeling, can successfully be used to elucidate the kinetic behavior of immobilized, oxygen-consuming, cells.<br/>},
  author       = {Hooijmans, C.M. and Geraats, S.G.M. and van Niel, Ed and Robertson, L.A.  and Heijnen, J.J. and Luyben, K.Ch.A.M.},
  issn         = {0006-3592},
  keyword      = {nitrification,denitrification,Thiosphaera pantotropha,immobilization,oxygen profiles},
  language     = {eng},
  pages        = {931--939},
  publisher    = {John Wiley & Sons},
  series       = {Biotechnology and Bioengineering},
  title        = {Determination of growth and coupled nitrification/denitrification by immobilized Thiosphaera pantotropha using measurement and modeling of oxygen profiles},
  url          = {http://dx.doi.org/10.1002/bit.260360908},
  volume       = {36},
  year         = {1990},
}