Broth recycle in a yeast fermentation
1994
Hsiao, T.Y. | Glatz, C.E. | Glatz, B.A.
Fermentation is a water-intensive process requiring treatment of large amounts of effluent broth. It is desirable to increase the ratio of product produced to the volume of effluent by minimizing the discharge of effluent from the fermentation process. A study of recycling spent fermentation broth for the subsequent fermentation was carried out with Apiotrichum curvatum, an oleaginous yeast, as the working culture. Spent broth from a defined medium was recycled to replace as much as 75% of the water and salts for subsequent batches and this was repeated for seven sequential batches without affecting cell mass and lipid production. A 64% volume reduction of wastewater was achieved in this manner. However, when using whey permeate as the medium, lipid production dropped after three consecutive recycle operations at 50% recycle, and after two consecutive recycle operations at 75% and 100% recycle. Accumulation of ions in the broth appeared to be responsible for the inhibition. An ion exchange step was able to eliminate the ion buildup and restore fermentation performance.
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