Centrifuges production scale

The yield of secondary metabolites in a large-scale fermenter typically ranges from 0.1 to lOg/L of broth. Such poor yield leads to cumbersome and expensive processes for both product separation and broth disposal. Within the last decade, several novel bioreactors have been developed for the intensification of fermentation processes. Examples include a centrifugal bioreactor, a rotating packed bed fermenter, and a sonobioreactor. Most of these, however, are yet to be implemented on a production scale because they generally lack practicality and well-defined scale-up criteria. 

After detachment of the flame from the walls, the narrow ever-diminishing hot product zone behind the flame moves owing to the free convection in the centrifugal acceleration field toward the axis of rotation, with a speed scaling with circumferential velocity at the flame location, which reduces the observed flame speed to very low values, and in some cases negative ones. 

To a first approximation, the cost of a single MPI is assumed to vary with scale (vessel volume or process throughput) on an exponent of 0.7. The value of this exponent does vary from one plant item type to another and while it typically lies in the range 0.5-0.9 [40, 42] for some equipment types (e.g., centrifuges) it may be at or above unity. This indicates that the purchased cost of equipment per unit production rate, say /(tons per year), generally increases as manufacturing scale decreases well known as economies of scale, related to large bulk chemical plants. 

In fine chemicals manufacture, batch filtration prevails. This operation is the subject of R D in various steps of process development. The aim of R D on filtration is (1) to establish an effective procedure of filtration and washing providing a filter cake and/or filtrate of desired quality, and (2) to select the most appropriate filter or centrifuge for full-scale operation and determine its productivity. The productivity is defined as ... 

The same method described in Procedure 2 (Section 12.1.2) was used for preparative-scale biotransformation of 150 mg of 2-methyl-1,4-naphthoquinone, except that reactions were incubated for only 72 h before being combined, centrifuged, extracted and chromatographically purified to give 50 % yield (92 mg) of product. 

Optimal fermentation parameters have been well established and air-lift, stirred tank, and hollow fibre systems have all been used. At commercial scale, fermentation volumes in excess of 1000 litres can be used, which can yield 100 g or more of final product. While hybridoma growth is straightforward, production levels of antibody can be quite low compared with ascites-based production systems. Typically, fermentation yields antibody concentrations of 0.1-0.5 mg/ml. Removal of cells from the antibody-containing media is achieved by centrifugation or filtration. An ultrafiltration step is then normally undertaken in order to concentrate the filtrate by up to 20-fold. 

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