Chemical oxygen demand reduction in a whey fermentation

Moresi, Mauro; Colicchio, Alberto; Sansovini, Fabio; Sebastiani, Enzo

doi:10.1007/bf00508103

Cited by 13 publications

References 5 publications

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Optimal design of airlift fermenters

Moresi

1981

Biotech & Bioengineering

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SummaryIn this article a modeling of a draft-tube airlift fermenter (ALF) based on perfect backmixing of liquid and plugflow for gas bubbles has been carried out to optimize the design and operation of fermentation units at different working capacities. With reference to a whey fermentation by yeasts the economic optimization has led to a slim ALF with an aspect ratio of about 15. As far as power expended per unit of oxygen transfer is concerned, the responses of the model are highly influenced by kLa. However, a safer use of the model has been suggested in order to assess the feasibility of the fermentation process under study.

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Optimal design of airlift fermenters

Moresi

1981

Biotech & Bioengineering

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The ejector‐loop fermenter: Description and performance of the apparatus

Moresi¹,

Gianturco²,

Sebastiani³

1983

Biotech & Bioengineering

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A novel fermentation unit, the ejector-loop fermenter (ELF), consisting of an outer-loop tower fermenter, a centrifugal pump, a plate-heat exchanger, and a gas-liquid ejector, was designed and constructed. Aeration was achieved by continuously recirculating the fermentation medium through two different nozzle devices instead of using the traditional expensive air compressor. By carrying out a whey fermentation with Kluyveromyces fragilis as the test organism, either in the ELF or in conventional stirred fermenter, it was possible to confirm that the high sheat streses and mixing shock occurring in the ejector nozzle and diffuser sections did not affect microbial growth. Within the range of experimental power consumption per unit volume (-0.1-5 kW/m(3)), the oxygen transfer capability of the ELF per unit power input was found to vary from 1 to 2.5 kg O(2) kW(-1)h(-1). Moreover, it is shown that there is suficient room for improvement in the performance of the ELF unit by care fully designing the aeration device. In fact, at constant volumetric oxygen transfer coefficient, the power consumpotion per unit volume in a 4-mm nozzle was found to be about 40% less than that in a 6-mm nozzle.

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