Method of producing carboxylic acid
Efficient production of a carboxylic acid is provided by a method of producing a carboxylic acid, which includes the following steps (A) and (B): (A) filtering a carboxylic acid-containing fermentation broth by passing said fermentation broth through a nanofiltration membrane, to obtain a carboxylic acid-containing filtrate from the permeate side of the membrane; and (B) extracting the carboxylic acid from the carboxylic acid-containing filtrate obtained in the step (A) using an extraction solvent which undergoes phase separation with the filtrate, and collecting a carboxylic acid extract phase-separated from the aqueous phase.
1 . A method of producing a carboxylic acid, comprising:
(A′) removing insoluble substances from a carboxylic acid-containing fermentation broth;
(A) filtering said insoluble substances-removed carboxylic acid-containing fermentation broth by passing said insoluble substances-removed carboxylic acid-containing fermentation broth through a nanofiltration membrane to obtain an aqueous carboxylic acid-containing filtrate that is free of organic solvent from a permeate side of said nanofiltration membrane and to accelerate phase separation between an aqueous phase and an organic phase in step (B); and
(B) mixing said carboxylic acid-containing filtrate obtained in step (A) with an extraction solvent which undergoes the phase separation with said carboxylic acid-containing filtrate, and collecting a carboxylic acid extract phase-separated from the aqueous phase.
2 . The method according to claim 1 , wherein said carboxylic acid-containing fermentation broth and/or said carboxylic acid-containing filtrate is adjusted to a pH of 4.5 or less.
3 . The method according to claim 1 , wherein said step of removing the insoluble substances is a step of passing said carboxylic acid-containing fermentation broth through a microfiltration membrane.
4 . The method according to claim 1 , wherein said carboxylic acid to be produced is acetic acid, succinic acid, itaconic acid, adipic acid, 3-hydroxyadipic acid, 3-hydroxyadipic acid-3,6-lactone, α-hydromuconic acid, muconic acid, 4-hydroxybenzoic acid, phenylalanine, tyrosine, or histidine.