Consider a process to recover an extracellular product expressed in E Coli cells. The total fermentation broth volume of the mixture of product, cells, and liquor is 1000 L. In this case cell concentration is 100g/L and product concentration is 2 g/L. Data on soluble contaminants are not available. We will assume that the density of the cells and liquor is the same as that of water (1000 kgm-3). A single stage experiment using an existing centrifuge showed that the process gives 60% product yield with 100% removal of cells.

1). Calculate the required process conditions in order to increase the yield to 80% by:

(a) Increasing the dewatering level in a single centrifuge step.

(b) Prediluting the feed by buffer and using the existing centrifuge in a single step.

(c) Using the existing centrifuge and washing the sediment in a two steps setting. A concentration step using a microfiltration process yields 20% of product for a concentration factor of 2.

2). How much diafiltration liquor is needed in order to increase the yield to 80% after this concentration stage? 3). Use the calculated data above to compare and contrast the three centrifuge and microfiltration operations as methods of preparing a clarified product feed stream prior to chromatography.