Recovery of organic acid salts from impure process streams by addition of bases

An improved process for the recovery of an organic acid salt from a fermentation broth containing such organic acid and/or salt thereof, comprising the steps of:

• a. fermenting an appropriate carbon and hydrogen source as a substrate in the presence of an appropriate microorganism to produce a fermentation broth containing a desired organic acid and/or salt thereof together with impurities including the biomass residue of the microorganism;
• b. treating the fermentation broth to substantially remove the biomass, thereby providing a partially purified fermentation broth containing the organic acid and/or salt thereof, unreacted substrate and other impurities;
• and the steps c and d in either order,
• c. neutralizing any residual organic acid in the partially purified fermentation broth to produce the desired organic acid salt with a neutralizing base in which the cation is the same as that in the desired salt;
• d. treating the neutralized partially purified fermentation broth to provide a solution of the desired organic acid salt, concentrated to within about ten percent (by weight) of the saturation point;
• e. adding a sufficient amount of a crystallizing base to the concentrated solution to produce the organic acid salt crystals;
• and
• f. separating the organic acid salt crystals from mother liquor.

An improved process for the recovery of an alkali metal or alkaline earth metal salt of citric acid from a fermentation broth containing citric acid and/or a salt thereof, comprising the steps of:

• a. fermenting an appropriate carbon and hydrogen source as a substrate in the presence of an appropriate microorganism to produce a fermentation broth containing citric acid and/or a salt thereof together with impurities including the biomass residue of the microorganism;
• b. treating the fermentation broth to substantially remove the biomass, thereby providing a partially purified fermentation broth containing citric acid and/or salt thereof, unreacted substrate and other impurities;
• and the steps c and d in any order,
• c. neutralizing any residual citric acid present in the partially purified fermentation broth with a base in which the cation is the desired alkali metal or alkaline earth metal cation to produce the desired alkali metal or alkaline earth metal citrate salt;
• d. treating the neutralized fermentation broth to provide a solution of the desired alkali metal or alkaline earth metal citrate salt, concentrated to within about ten percent (by weight) of the saturation point;
• e. adding a sufficient amount of a crystallizing base to the concentrated solution to produce alkali metal or alkaline earth metal citrate salt crystals;
• and
• f. separating the alkali metal or alkaline earth metal citrate salt crystals from mother liquor.

An improved process for recovering an alkali metal or alkaline earth metal salt of citric acid from an impure process stream, comprising the steps of:

• the steps a and b in any order,
• a. obtaining a solution of a desired alkali metal or alkaline earth metal citric acid salt, concentrated to within about ten percent (by weight) of the saturation point;
• b. adding a sufficient amount of a crystallizing base to the concentrated solution of the alkali metal or alkaline earth metal citric acid salt to crystallize the salt;
• and
• c. separating the salt crystals from mother liquor.

An improved process for the recovery of an alkali metal salt of citric acid in combination with the fermentation of citric acid and recovery by a solvent extraction or lime sulfuric process, comprising the steps of:

• the steps a and b in any order,
• a. treating an impure process stream resulting from a solvent extraction or lime-sulfuric recovery process to obtain a saturated solution of an alkali metal citric acid salt which solution also contains other impurities;
• b. adding a crystallizing base chosen from the group consisting of sodium hydroxide, potassium hydroxide and ammonia to the concentrated solution to produce the alkali metal citric acid salt;
• and
• c. separating the alkali metal salt crystals from the mother liquor.