Bio-Adipic Acid Production from Glucose (Fermentation Process)

The process under analysis comprises two major sections: (1) Fermentation; and (2) Purification.

Fermentation. The culture media used in the pre-fermentation and in the fed-batch fermentation are prepared by diluting the glucose syrup and nutrients in water. The applied recombinant microorganism is propagated in an aerobic pre-fermentation step to obtain the proper inoculum concentration. When there is a sufficient mass of bacteria colony, the microorganism inoculum from the pre-fermentation step is fed into the fermentors. Fed-batch medium is continuously supplied to the fermentors, and the main fermentation is carried out under anaerobic process conditions. The pH control is made by addition of a solution of ammonia (NH3), so as to keep the pH of the fermentation broth around 7. Due to the presence of the ammonium hydroxide, most of the Adipic Acid produced is neutralized, in such a way that the broth contains Adipic Acid mainly in its conjugate base forms.

Purification. After fermentation, biomass is separated from the broth. The clarified broth then is submitted to an ultrafiltration step, used to remove the remaining contaminants. The resulting Adipic Acid solution then passes through a salt split and two successive crystallization steps for concentration and purification. The final product obtained is 99.9 wt% Adipic Acid.