DD285792A5 - METHOD FOR SEPARATING AND PROCESSING ORGANIC SOLVENTS FROM FERMENTATION MESDIA - Google Patents

Abstract

The invention relates to a process for separating and working up organic acids from fermentation media. The invention relates to the separation of carboxylic acids from fermentation media, as well as the subsequent separation of by-products, as they are frequently found in fermentation processes. In this case, preferably media are processed, resulting from the continuous fermentation with immobilized microorganisms. The fields of application of the invention include the food industry, pharmacy, medicine, as well as the chemical industry and biotechnology. According to the invention, the carboxylic acids are quantitatively removed from the fermentation medium by means of anion exchangers with quaternary ammonium groups, which have been converted into the bicarbonate form by treatment with bicarbonate solution. By replacing the bicarbonate ions, there is no direct loading of the fermentation medium with foreign ions, so that the treated fermentation medium can, if necessary, be returned to the reactor. Through the laundry of the exchange resin with alkanolic solvent, the uncharged contaminants adsorptively adhering to the exchanger can be removed. The elution of the organic acids, as well as the conditioning of the exchange resin for re-use is achieved by treatment with sterile bicarbonate solution. The conversion of the salts of carboxylic acids into the free acid form is carried out by treatment of the solution with cation exchanger in the proton form. citric acid; anion exchanger; Cation exchanger; Separation; separation; Fermentation}

Description

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Field of application of the invention

The invention relates to a method for the separation of organic acids from fermentation media, which are produced in continuous fermentation processes, as well as the further work-up and separation of acid mixtures in their components in a simple manner.

The process can be used in the food industry, pharmacy and medicine as well as in the chemical industry and biotechnology.

State of the art The previously used methods for the fermentation of organic acids are usually batch processes, the

do not require immediate separation of the organic acids during the formation.

Thus, the patent DD 232723 Jon., A. Benckiser GmbH describes a method which dor the previously common form Separation of organic acids after completion of the fermentation process by calcium salt precipitation from the Fermentation medium combined with a variety of steps (membrane filtration, reverse osmosis, adsorption on Adsorber resin, calcium salt precipitation, calcium sulfate and separation of the cat and anions by ion exchanger). Only media from batch fermentations are used for processing. In the patent DE 3328093 a method was presented by Hoechst AG with which by means of polymers, the tertiary Carrying amino groups, the free acids are removed directly from a continuously conducted process. The disadvantage of this Solution is that the pH in the fermentation room only by complete separation of the acids from the medium,

or permanent correction can be kept constant by means of appropriate alkaline solutions.

Complete binding of the acids, however, is not present during the entire loading phase on the exchange resin,

whereby an analysis of the quality and quantity dec bonded organic acids during the Fernentationsverlaufes difficult.

Object of the invention

The aim of the invention is a method for the continuous.-) separation of organic acids in a simple, environmentally friendly and economical way, which can be applied to continuous FermenKtionsprozessen and at the same time a determination of the quality of the Fermontationsprozesses <i ^ equips.

Darling of the essence of the invention

The invention has for its object to remove organic acids quantitatively and continuously from the fermentation medium and reuse the acid-free medium for fermentation.

According to the invention the object is achieved by the use of anion exchangers with quaternary ammonium groups, the

made sterile by treatment with sodium hydroxide solution, sterile sodium carbonate solution and sterile sodium bicarbonate solution and at the same time converted into the stable form of hydrogencarbonate.

In the continuous separation of the organic acids, the exchange of acid ions takes place against Hydrogencarbonationenquantiativ. At the beginning of the fermentation process, the organic acids formed by dilute sodium hydroxide in the usual Neutralized and enriched to a concentration of 1.5 to 3.0 g / ml fermentation medium. Will now be enriched with neutralized organic acids fermentation medium over t'en in the Hydrogen carbonate form given anion exchanger, finds a complete replacement of the Hydrogencarbonationen against acid anions on the anion exchanger instead. The fermentation solution is then added to the reactor

fed again. The excess of alkalinity of the treated solution resulting from the replacement process can be advantageously used to neutralize the further formed; Acids are used. The excess carbon dioxide, which can not be dissolved in the fermentation medium at the corresponding pH, is discharged from the fermenter with the waste gas.

The flow rate can be adjusted so that the pH remains in the desired range. The amount of the separated organic acids corresponds exactly to the formed organic acids and can be easily

calculate from the flow volumes.

Loading of the fermentation medium with foreign salts does not occur in this form of neutralization. The determination of Quality of the fermented organic acids is determined by sampling from the fermentation medium and suitable Realized analytical methods. It is advantageous to provide two exchanger columns which are arranged in parallel and which are bidded together. The Loading with fermentation medium is carried out in an upflow, the subsequent elution is carried out in the outflow. By flushing the exchanger column with alkanolic solvent, adsorptively bound impurities are released

Wash the fermentation medium from the cation exchange resin. The solvent can easily be recovered by distillation.

According to the invention, the organic acids bound on the exchanger are saturated by sterile Sodium bicarbonate solution eluted. Elution may also be by means of a gradient between sterile water and sterile Sodium bicarbonate solution. The application of the elution variant should be chosen according to the separation problem. The Adsorbersäule remains in the sterile state and is

immediately ready for use after elution.

In the eluate, the bicarbonate is converted into free carbonic acid by means of strongly acidic cation exchangers in the proton form

and the salts of the organic acids are converted to the free acid form. The solution of the free acids can then be concentrated by suitable methods in a known manner and brought to crystallization.

As shown in Figure 1. the sterilized columns are alternately loaded or eluted. To protect the columns

(a & b) against contamination with organic of the culture strain from dom fermentation space or foreign infections from the

Elution and wash water, the sterile filter (c u.d) are used in each case.

Exemplary embodiments Example 1

subjected to a three times Regenerier- and Beladecyclus (alternately charged with dilute sodium hydroxide solution, dilute hydrochloric acid and intermediate washing with distilled water) to remove any impurities, especially amines from the synthesis process. This is followed by the conditioning of the resin with 210 ml of 5% sodium hydroxide solution, then with 210 ml of 5% sodium carbonate solution and 210 ml of 5% sodium bicarbonate solution, which were previously sterilized. The process is complete after washing with sterilized distilled water.

After this treatment, the exchanger reads in bicarbonate form and is free of infection. From a 500 ml bioreactor with immobilized citrate-accumulating yeasts is in each case as much fermentation medium

passed the exchanger column, and returned to the reactor, that the pH in the fermenter maintains values between 5.0 and 5.2.

The specified amount of flow can be circulated for 5 to 7 days until the exchange resin with organic Loaded acids. The depletion of the exchanger becomes evident when the pH of the recycled medium has dropped from 8.2 to 7.2. The drop of the pH takes place under the conditions mentioned within a short time. After exhausting the column capacity, the column is exchanged for a second, also prepared. For the separation of the adsorptively bound to the exchange resin impurities from the fermentation, the predominantly

consist of polyalcohols, the Austai - chersäule is rinsed with 500ml of ethanol.

For the column loaded with citrates is covered with a gradient of water and saturated aqueous solution Sodium hydrogecarbonate solution eluted. The gradient is linear with a volume of 8-8.5 bed volumes. The faction

between 2.5 and 5.0 bed volume is used to remove excess bicarbonate via a column

Cationic Astacian wofatite KPS elutes in the proton form. It also adds the salt of the acid to the free acid

transferred.

In the thus treated eluate is citric acid in a concentration of 20 to 50g / l. The by-products like Ketoglutaric acid are separated. The solution of the acid can then be gobracht in known Weioe for crystallization. Example 2 A glass filter column as described in Example 1 is filled with 6OmI strongly basic anion exchanger Wofatit SZ30 and

converted into the bicarbonate form analogously to Example 1.

A 500ml bioreactor is filled with immobilized, isocitrate-accumulating yeasts and the resulting Fermentation medium prepared according to Example 1. The loading and Elutionsvorydng is analogous to Example 1, but the elution fraction contains between 2.5 and S. Bed volume primarily Isocitrst, which is worked up as the citric acid and crystallized.

Claims (6)

1. A process for the separation and workup of organic acids from fermentation media, characterized in that during the fermentation process, a certain amount of fermentation solution constantly passed through an anion exchanger with quaternary Ammon.umgruppen and recycled to the reactor. The exchanger is preferably in the form of bicarbonate, which in exchange for organic acids so much alkalinity is released that the pH value can be kept constant in the fermenter by the recirculated volume flow. 2. The method according to claim 1, characterized in that for the elution of the organic acid ions, preferably a sterile sodium bicarbonate solution is used. A process according to claim 2, characterized in that the mixtures of carboxylic acids can be separated by use of an elution gradient. 4. The method according to claim 2, characterized in that the separation of the adsorptively bound on the exchanger by-products is preferably carried out by a preceding elution step with alkanols before the actual desorption of the organic acids. 5. The method according to claim 2, characterized in that the eluate is then passed through a strongly acidic cation exchanger in the proton form, whereby the free acid form of the carboxylic acids can be obtained. 6. The method according to claim 1 to 5, characterized in that the sterility of the elution and washing waters and the refurbished Fsrmentationsmedien ensured by upstream sterile filter.