In the separation of microorganisms from fermentor growth media, a separating agent such as an alcohol, is added to the fermentor effluent to facilitate separation of the cellular material. A portion of the spent media and separating agent is recycled to the fermentor as carbon energy source therein. Further alcohol separating agent is separated from the balance of the spent media and reused for separation purposes or for use in the fermentor.
Alcohol is suitable for the extraction of salt from biomass-containing suspensions, in particular from the salt-containing lower phase of an aqueous 2-phase extraction of intracellular proteins after cell disruption, with the formation of a salt-containing alcoholic upper phase. It is possible to use ethanol, propanol, isopropanol or tert.-butanol, but especially ethanol, as the alcohol. The upper phase is separated from the lower phase by disk separators or decanters. The extraction is carried out, in particular, as a countercurrent extraction in at least three stages, and uses 10 to 30% by weight salt-containing suspension or liquid with 30 to 50% by weight alcohol, in particular ethanol, remainder water. The alcohol is removed from the resulting salt-rich upper phase by evaporation, and the salt solution is recycled where appropriate after further concentration to obtain proteins.
A continuous fermentation process for the production of single cell protein employing fermentation apparatus for improved oxygen utilization comprising a fermentation section and an upper contiguous absorber section communicating therewith wherein a gas contacting zone is employed to contact cooled recycled fermentation liquid and make up nutrients with partially oxygen depleted oxygenating gas in countercurrent flow whereby the oxygen content of the fermentation liquid is enriched.
A single cell protein plant is operated to produce high density cell growth and a substantially pure stream of generally high pressure carbon dioxide for further use, for example, in enhanced oil recovery operations. The plant employs an air separator producing substantially pure streams of oxygen and nitrogen. The oxygen stream is used to enrich a carrier fluid and used for aeration of the fermenter. The off-gases from the fermenter are separated into a generally high pressure, substantially pure carbon dioxide stream which can be used for enhanced oil recovery and a residual recycle stream to which oxygen is again added and which is returned to the fermenter. The single cell protein is dried and further processed as required for human or animal consumption.
A fermentation apparatus comprising a fermentation section; and a contiguous upper absorber section comprising a gas-contacting zone, gas-venting means, liquid knock-out zone, means adapted to receive recycle lean fermentation liquor, means adapted to receive makeup water and nutrients, and means to pass gaseous effluent from the fermentation section through the absorber section.
