Method for extracting molecules produced by anaerobic fermentation from fermentable biomass
Process for extracting volatile fatty acids (VFA), organic molecules called precursors produced by microorganisms (M) in a fermentation reactor ( 2 ) by anaerobic fermentation ( 3 ) using fermentable biomass ( 1 ), said molecules being fermentative metabolites, comprising at least the following steps: a) selecting an extraction means ( 8 ) from extraction means that is, at least, insoluble in the fermentation medium and the processing conditions of which preserve the capacity of the microorganisms (M) present in the fermentation medium to produce the molecules, b) bringing the chosen extraction means ( 8 ) into contact ( 9 ) with the fermentation medium without interrupting the fermentation ( 3 ), c) recovering ( 12 ) the extracted molecules, at a pH lower than 4.5, by the extraction means ( 8 ) outside the fermentation reactor ( 2 ). The invention also relates to an installation for implementing the method.
1. A process for extracting volatile fatty acids (VFA) produced by microorganisms in a fermentation reactor by anaerobic fermentation using fermentable biomass, said volatile fatty acids (VFA) being fermentative metabolites, the process comprising the following steps:
a) selecting liquid or solid extraction means that is insoluble in the fermentation medium and which preserves the capacity of the microorganisms present in the fermentation medium to produce said volatile fatty acids (VFA),
b) bringing the extraction means into contact with the fermentation medium without interrupting the fermentation, thereby extracting the volatile fatty acids (VFA) from the fermentation medium,
c) recovering the extracted volatile fatty acids (VFA) from the extraction means at a pH lower than 4.5, outside the fermentation reactor wherein the extraction means is a solvent having a boiling point lower than 70° C. and having a boiling point lower than the fermentation temperature.
2. The process according to claim 1 , wherein the extraction means is a solvent whose density is less than a density of the fermentation medium.
3. The process according to claim 1 , wherein the extraction means is a solid, and the extraction process is a solid-liquid type.
4. The process according to claim 1 , wherein bringing the extraction means into contact with the fermentation medium takes place in the reactor.
5. The process according to claim 1 , wherein bringing the extraction means into contact with the fermentation medium takes place outside the reactor, and the fermentation medium being is sampled continuously.
6. The process according to claim 1 , wherein bringing the extraction means into contact with the fermentation medium takes place outside the reactor, and the fermentation medium is sampled sequentially.
7. The process according to claim 1 , wherein, after step c), at least one part of a liquid phase resulting from the extraction process is reintroduced into the fermentation reactor and incorporated into the fermentation medium.
8. The method according to claim 1 , wherein the extraction process is a liquid-liquid type.