Succinate separation strategies

Another separation strategy uses the formation of diammonium succinate, where the ammonium ion is used to control the pH in the fermentation. The diammonium succinate can be concentrated and reacted with a sulfate ion at low pH to yield ammonium sulfate and succinic acid. Succinic acid has very low solubility in aqueous solutions with a pH below 2 and can be crystallized. The succinic acid can be purified with methanol, and the ammonium sulfate is thermally cracked into ammonia and ammonium bisulfate. The ammonia can be fed back into the fermenter, and the ammonium bisulfate can be recycled for use in succinic acid crystallization (Berglund et al. 1999). 

The downstream domain of the microbial production of FA has imposed a major economical barrier to entry into commercial trade for this multifaceted organic acid. As compared to the well-established downstream strategies for different fermented organic acids such as lactic acid, succinic acid, and citric acid, separation techniques for FA from the fermented broth have not met the conditions for scaling up in both economical and technical aspects. 

---