Succinic electrodialysis

There are several companies and groups that are developing bio-based succinic acid production for commercial use. The Showa group possesses a unique technology for purification of succinic acid from fermentation broth. This is the fractional crystallization method starting from sodium succinate. The yield by this method is around 70%, but we can recycle the residual solution so that we can minimize the loss of the product. We also compared the cost-effectiveness of this method with the bipolar electrodialysis method. The cost of our purification process seemed to be about half (our internal data). 

Separations research has resulted in the development of a two-stage desalting and water-splitting electrodialysis system that concentrates, purifies, and acidifies the succinic acid. The base is recycled back to the fermentation, where it is used for neutralization, eliminating the generation of gypsum salt, an unwanted neutralization byproduct that must be disposed of or sold (38). 

Electrodialysis uses stacks of pairs of anion- and cation-exchange membranes in deionizing water and in recovery of formic, acetic, lactic, gluconic, citric, succinic, and glutamic acids from their sodium and potassium salts in fermentation broths.114 This may have an advantage over processes that involve purification through calcium salts. Electrodialytic bipolar membranes have been used to recover concentrated mineral acids from dilute solution.115 They can be used to convert sodium chloride to hydrogen chloride and sodium hydroxide in a process that avoids the use of chlorine.116 Soy protein has been precipitated by... 

The main objective of this development was to produce a purified succinic acid product for the catalytic conversion and a solution of ammonium succinate for a new application. TTie process used was a two-stage desalting and watersplitting electrodialysis process. This double-dialysis process avoids the generation of large quantities of salt wastes, which is a common problem in the recovery of fermentation-derived organic acid such as citric acid by the gypsum process (21). The actual fermentation broths from the 75-liter and 500-liter scale-up experiments performed at ORNL were sent to ANL for use in the development of the product recovery and purification process. 

The water-splitting electrodialysis products still contained small amounts of impurities, and aliquots of them were further purified by using different polishing schemes to evaluate the efficacy of each scheme. Table II shows the impurity profiles of purified succinic acid products obtained from different polishing schemes. 

Water-splitting electrodialysis can be improved by using a supersaturated solution of the fi-ee acid. Sodium acetate inhibits crystallization of succinic acid, but free acetic acid, which is produced by water-splitting electrodialysis, promotes crystallization of succinic acid (Berglund et al. 1991). 

The costs of separation of succinic acid will be a critical component in economical production of this acid. As acids are neutralized in the fermentation to maintain an appropriate pH for the microorganism, the salts formed must eventually be removed and can be a waste generation problem. Promising separation technology is the use of liquid-liquid extraction and water-splitting electrodialysis. Key also to lowering separation costs is the development of microorganisms that produce as few by-products as possible which need to be removed from the final product stream. 

Membrane filtration/ electrodialysis Relatively mild conditions can be used for continuous separation High energy consumption high cost of the membranes low selectivity for succinate Wang et al. (2012, 2014)... 

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