Fermentation organic acids recovery

BPMs offer a solution to the cation elimination problem accompanying most organic acids They allow a salt to be split into the corresponding alkali and acid solutions. Consequently, BPMs are used in water-splitting processes and offer possibilities for organic acid recovery from fermentative production. In addition, the decrease in ionic strength induced by cation demineralization coupled with acidification of the solution was also used for the production of phospholipids. 

The incomplete comprehension of mass transfer mechanisms in ED membrane systems is in all probability responsible for the difficult design of industrial plants and for their limited diffusion. For instance, in the food biotechnology sector ED applications are still in their infancy since quite a limited number of the novel processes studied so far in laboratory- and pilot-scales and reviewed here have been converted into industrial realities yet, except for the recovery of the sodium salt of unspecified organic acid from clarified fermentation broths, as well as amino and organic acids (Gillery et al., 2002). 

It may also be economical to remove the inhibitory product directly from the ongoing fermentation by extraction, membranes, or sorption. The use of sorption with simultaneous fermentation and separation for succinic acid has not been investigated. Separation has been used to enhance other organic acid fermentations through in situ separation or separation from a recycled side stream. Solid sorbents have been added directly to batch fermentations (18,19). Seevarantnam et al. (20) tested a sorbent in the solvent phase to enhance recovery of lactic acid from free cell batch culture. A sorption column was also used to remove lactate from a recycled side stream in a free-cell continuously stirred tank reactor (21). Continuous sorption for in situ separation in a biparticle fermentor was successful in enhancing the production of lactic acid (16,22). Recovery in this system was tested with hot water (16). 

These applications are based on water dissociation at the interface of a bipolar membrane and are coupled with the action of the monopolar membrane action. Deacidification and acid production, however, entail conventional ED. In the recovery of organic acids from fermentation broths the elimination of cations has often been a major problem, as fermentation typically performs better in pHs significantly above the pfC, of the acid produced. Bipolar membranes offer a solution to the elimination... 

Fermentation broths tend to be very dilute and contain complex mixtures of inorganic or organic substances. The recovery of a soluble product (MW range 500-2500 dalton) such as an antibiotic, organic acid or animal vaccine from fermentation broth takes several processing steps. The first step is the clarification of broth to separate the low molecular weight soluble product from microorganisms and other particulate matter such as cells, cell debris, husks, colloids and macromolecules from the broth me-dium.l l In this step, microporous membrane filters (MWCO 10,000 to... 

These applications include the in-situ recovery of fermentation products. This would be particularly useful in fermentations where the major product inhibits growth or production rates. Examples include those systems which produce organic acids such as acetate and lactate. Perhaps the most useful application would be the down-... 

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. 

As expected, recovery of the calcium salt of organic acids, mainly calcium lactate, from the culture medium needs attention, but little has been reported. Calcium lactate is formed during fermentation and precipitates, which can be removed by washing. The resulting organic salts from the DM process could be used as de- and anti-icing agents and/or preservatives. 

The cost of recovery of sucdnic add will be of prime importance in determining whether a cost-effective process will allow succinate-derived chemicals to compete with petrochemicals. Most succinate fermentations need to be run at or near a neutral pH and require the addition of a salt to maintain pH. Removal of the salt to achieve the isolation of the desired add is one of the challenges of developing a low-cost separation process. Various approaches toward the recovery of organic adds have been tried, but it is beyond the scope of this chapter to review organic acid separation technology. Some work has focused specifically on succinic acid and that is what will be covered here. 

The two major weaknesses of the fermentation process for propionic acid production are the low final product concentration and the extremely low productivity due to the sensitivity of the bacterial cells to organic acids and their slow fermentation and growth rates. Two developments in fermentation technology that improve the process are the high cell density reactor and improved ultrafiltration membranes for recovery of the product. 

Orjuela A, Yanez AJ, Peereboom L, Lira CT, Miller DJ (2011) A novel process for recovery of fermentation-derived succinic acid. Sep Purif Technol 83 31-37 Otero JM, Cimini D, Patil KR, Poulsen SG, Olsson L, Nielsen J (2013) Industrial systems biology of Saccharomyces cerevisiae enables novel succinic acid cell factory. PLoS One 8 1-10 Ponnampalam E (1999) Purification of organic acids using anion exchange chromatography. Patent WO9944707... 

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