Chemical oxygen demand reduction in a whey fermentation

  • Mauro Moresi
  • Alberto Colicchio
  • Fabio Sansovini
  • Enzo Sebastiani


The efficiency of Chemical Oxygen Demand (COD) reduction η in the fermentation of whey by Kluyveromyces fragilis IMAT 1872 was studied at various temperatures, lactose concentrations, air dilution ratios and stirring speeds. Their effects on the biomass yield (y) has been determined previously (Moresi et al. in press).

Two different optimal sets of these variables were found according to whether the objective was the production of cell mass or the reduction of COD. The two sets were then compared to establish a strategy for the industrial development of this fermentation process.

The experimental efficiencies of COD removal were submitted to analysis in a composite design. Only the first two principal axes (i.e., the ‘oxygen transfer coefficient’ factor and the ‘stripping’ factor) of canonical analysis were found to be significant by an F-test. Therefore, the observations were fitted with a quadratic expression by using only these factors: the mean standard error was less than 6%.

The yield of cells, expressed as g of dried cells/g of COD removed, varied in this fermentation, but this parameter may be particularly useful for analyzing and optimizing any fermentation process when the culture medium is a mixture of carbohydrates or the main substrate is fully utilized during the initial stages of fermentation.


Fermentation Lactose Chemical Oxygen Demand Fermentation Process Biomass Yield 



Air dilution ratio, litre/min of air per litre of liquid, vvm


Generic coefficient of Eq. (2)


Generic eigenvalue of the matrix of coefficients bij


Chemical oxygen demand, g/l


Initial lactose concentration, g/l


stirrer speed, min−1


Direction cosine of xj and Vi


variance of regression


Temperature, °C


Generic eigenvector of the matrix of coefficients bij


Dimensionless temperature


Dimensionless lactose concentration


Dimensionless air dilution ratio


Dimensionless stirrer speed


Biomass yield, g of dried cells/g of initial lactose


Overall yield for cell growth, g of dried cells/g of COD removed

Greek letters


Net biomass accumulation, g/l


COD reduction per unit volume of liquid, g/l


Efficiency of COD reduction, (CODo-CODf)/CODo, dimensionless


Maximum efficiency of COD reduction, dimensionless


Degrees of freedom


Error variance of factorial design







Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Amundson C H (1967) Amer. Dairy Rev 29: 22Google Scholar
  2. ASTM Standards (1964) Industrial water: atmospheric analysis', Part 23. p 233, D 1252-60Google Scholar
  3. Bechte R M, Claydon T J (1971) J Dairy Sci 54: 1595Google Scholar
  4. Bernstein S, Tzeng C H Commercial production of protein by the fermentation of acid and/or sweet whey. Environmental Protection Technology Series, EPA-600/2-77-133, July 1977Google Scholar
  5. Davies O L (1956) The design and analysis of industrial experiments. Imperial Chemical Industries Limited, LondonGoogle Scholar
  6. Devos P (1960) French Pat No 1, 213, 446Google Scholar
  7. Eurostat (1977) Milk and milk products. pp 36–37Google Scholar
  8. Fonden R, Pettersson L (1974) XIX Int. Dairy Congress, 1E: 816Google Scholar
  9. Himmelblau D M (1970) Process analysis by statistical methods. J. Wiley, New YorkGoogle Scholar
  10. Moresi M, Colicchio A, Sansovini F (1979 accepted for publication) Optimization of whey fermentation in a jar fermenter. Eur J Appl Microbiol Biotechnol in pressGoogle Scholar
  11. Moresi M, Sebastiani E (1979) Eur J Appl Microbiol Biotechnol 8: 63Google Scholar
  12. Moulin G, Galzy P (1976) Ind. Aliment Agr 93: 1337Google Scholar
  13. Muller H (1976) US Pat. No 3,968,257Google Scholar
  14. Robe K (1964) Food processing, Chicago 25: 95Google Scholar
  15. Société des Alcools du Vexin (2963) French Pat No 80, 198Google Scholar
  16. Stimpson E.G., Young H. (1957) US pat. No 2,809,113Google Scholar
  17. Tomisek J, Gregr V (1961) Kvasny Prumysl 7: 130Google Scholar
  18. Vernois G (1970) Le Lait 493–494: 137Google Scholar
  19. Wasserman A E (1960) Dairy Eng 77: 374Google Scholar
  20. Yates F (1937) Design and analysis of factorial experiments. Imperial Bureau of Soil Science, LondonGoogle Scholar

Copyright information

© Springer-Verlag 1980

Authors and Affiliations

  • Mauro Moresi
    • 1
  • Alberto Colicchio
    • 1
  • Fabio Sansovini
    • 1
  • Enzo Sebastiani
    • 1
  1. 1.Instituto di Chimica Applicata e Industriale, Facolta' di IngegneriaUniversita' di RomaRomeItaly

Personalised recommendations