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Title: Production of ammonium lactate in an immobilized cell system
Author: Pearce, J. D.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1986
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The objective of this work was to develop a continuous immobilized cell reactor system for the high rate production of ammonium lactate using deproteinized whey as a substrate. Further that this system should use techniques other than membranes to retain cells. The fermentation was carried out using a mixed culture of homofermentative thermophilic lactic acid bacteria selected by an enrichment technique. Immobilization was achieved by retaining the culture as a slime-film supported on a needle-punched polyester fabric, placed as a pleated tube in a column reactor. Flocculation was used to obtain further improvements in biomass retention. Two reactors of volume 0.2 litres were used for most of the experiments. The height to diameter ratios of these reactors were 2.2 and 7.3. The latter was designed to encourage flocculation and the diameter at the top was slightly larger, than at the bottom. The pH was continuously controlled by the addition of ammonium lactate. The influences of temperature, pH, residence time and yeast extract (added to the feed) were studied. When both methods of hold up were combined acid productivities up to 18 kg/m3/hr at a conversion rate of 0.95 could be obtained. The system was operated for up to 850 hours without a deterioration in performance.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available