Influence of Substrate Distribution on Productivities in Computer Controlled Baker's Yeast Production

Scaling up bioprocesses is one of the most crucial steps in the commercialization of bioproducts. While it is known that concentration and shear rate gradients occur at larger scales, it is often too risky, if feasible at all, to conduct validation experiments at such scales. Using computational fluid dynamics equipped with mechanistic biochemical engineering knowledge of the process, it is possible to simulate such gradients. In this work, concentration profiles for the by-products of baker’s yeast production are investigated. By applying a mechanistic black-box model, concentration heterogeneities for oxygen, glucose, ethanol, and carbon dioxide are evaluated. The results suggest that, although at low concentrations, ethanol is consumed in more than 90% of the tank volume, which prevents cell starvation, even when glucose is virtually depleted. Moreover, long exposure to high dissolved carbon dioxide levels is predicted. Two biomass concentrations, i.e., 10 and 25 g/L, are considered where, in the former, ethanol production is solely because of overflow metabolism while, in the latter, 10% of the ethanol formation is due to dissolved oxygen limitation. This method facilitates the prediction of the living conditions of the microorganism and its utilization to address the limitations via change of strain or bioreactor design or operation conditions. The outcome can also be of value to design a representative scale-down reactor to facilitate strain studies.

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Integrated biological (anaerobic–aerobic) and physico-chemical treatment of baker's yeast wastewater

Water Science & Technology ◽

10.2166/wst.2005.0703 ◽

2005 ◽

Vol 52 (10-11) ◽

pp. 273-280 ◽

Cited By ~ 14

Author(s):

S. Kalyuzhnyi ◽

M. Gladchenko ◽

E. Starostina ◽

S. Shcherbakov ◽

B. Versprille

Keyword(s):

Separation Process ◽

Baker’S Yeast ◽

Uasb Reactor ◽

Baker's Yeast ◽

Organic Loading ◽

Cultivation Medium ◽

Loading Rates ◽

Physico Chemical ◽

Yeast Production ◽

Yeast Wastewater

The UASB reactor (35°C) was quite efficient for removal of bulk COD (52–74%) from simulated (on the basis of cultivation medium from the first separation process) general effluent of baker's yeast production (the average organic loading rates varied from 8.1 to 16g COD/l/d). The aerobic-anoxic biofilter (19–23°C) can be used for removal of remaining BOD and ammonia from anaerobic effluents; however, it suffered from COD-deficiency to fulfil denitrification requirements. To balance COD/N ratio, some bypass (∼10%) of anaerobically untreated general effluent should be added to the biofilter feed. The application of iron (III)-, aluminium- or calcium-induced coagulation for post-treatment of aerobic-anoxic effluents can fulfil the limits for discharge to sewerage (even for colour mainly exerted by hardly biodegradable melanoidins), however, the required amounts of coagulants were relatively high.

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