Treatment method of dicarboxylic acid fermentation liquor

Abstract

The invention discloses a treatment method of dicarboxylic acid fermentation liquor, which comprises the following steps: controlling pH and temperature, acidifying to a specific pH value, heating, adding dicarboxylic acid single salt and controlling temperature, promoting the demulsification of the fermentation liquor, layering the solution, separating and recovering upper alkane, carrying out solid-liquid separation on the lower solution containing the dicarboxylic acid single salt to obtain dicarboxylic acid single salt filtrate, and carrying out solid-liquid separation on the lower solution containing the dicarboxylic acid single salt to obtain the dicarboxylic acid single salt filtrate. And continuously adding acid for acidification to crystallize and separate out the dicarboxylic acid, and filtering, washing and drying to obtain the dicarboxylic acid. According to the treatment method disclosed by the invention, the dicarboxylic acid fermentation liquor is milder, the energy consumption is lower, the demulsification is better realized, more dicarboxylates are released, the alkane recovery and impurity separation are realized, the nitrogen content of the obtained dicarboxylic acid is lower, and the product quality is improved.

Description

Technical Field

[0001] The invention relates to a dicarboxylic acid fermentation liquid treatment technology, in particular to a fermentation liquid pretreatment process in a dicarboxylic acid primary product extraction process. Background Art

[0002] Dicarboxylic acids are metabolites produced by fermentation of microorganisms using alkanes or fatty acids as carbon sources. Its molecular formula is C n H 2n-2 O4, where n is 8-18, dicarboxylic acid contains two terminal carboxyl groups and is a monomer raw material for synthesizing engineering plastics and hot melt adhesives.

[0003] The composition is complex and alkaline, containing a three-phase mixed emulsion composed of alkanes, dicarboxylic acid disalanine aqueous solution and bacteria, as well as culture medium, bacteria, protein, dicarboxylic acid disalanine, inorganic salts and secondary metabolites. The emulsion floats on the upper layer of the fermentation liquid to form an emulsion layer, and the lower layer is mainly dicarboxylic acid disalanine aqueous solution and most of the bacteria. Among them, the demulsification of the emulsion of the fermentation liquid is the key in the pretreatment process of the fermentation liquid, which is related to the recovery rate of residual alkanes, the yield of dicarboxylic acid, the investment and treatment efficiency of filtration equipment and the quality of subsequent products.

[0004] The methods for treating emulsion in dicarboxylic acid fermentation broth include direct acidification demulsification method, heating demulsification method, demulsifier demulsification method and direct filtration with microfiltration membrane.

[0005] Direct acidification demulsification method, such as patent CN201310669931.6, uses fermentation broth to directly add acid to acidify the pH to ≤4, and then undergoes solid-liquid separation and drying to produce a crude product with a water content of ≤5%. Although the direct acidification of this patent can demulsify the fermentation broth, a uniform mixture of alkanes, dicarboxylic acid solids, acid water, etc. is formed, and it is difficult to further completely separate the alkanes from the long-chain dibasic acids. At the same time, acidification to a lower pH during the demulsification process can easily cause bacterial cells to rupture, and impurities such as intracellular proteins and intermediate metabolites are introduced into the dicarboxylic acids, resulting in an increase in the content of impurities such as protein in the extracted dicarboxylic acid primary product, which increases the difficulty of removing impurities in the subsequent refining process.

[0006] The heating demulsification method is to adjust the fermentation liquid to a pH of above 9 and heat it to 80-100, and then let it stand for a long time to break the emulsion layer, so that the alkanes gather in the upper layer, separate and recover the alkanes, and filter the lower dicarboxylate and the aqueous solution of the bacterial layer to extract the primary dicarboxylic acid product. People in the industry know that microbial cells are very easy to rupture and autolyze under high pH alkaline conditions, and a large amount of intracellular proteins and metabolic intermediates are released, resulting in a large increase in impurities in the extracted primary dicarboxylic acid products, and increasing the difficulty of removing impurities in subsequent refining processes.

[0007] Demulsifier demulsification method is to adjust the fermentation liquid to pH 9 or above and add demulsifiers such as urea to break the emulsion layer. It has the same disadvantages as the above-mentioned alkali demulsification, that is, cell rupture and autolysis lead to the release of protein and metabolic intermediates, and introduce new impurities, which increases the investment cost of demulsifier and the subsequent treatment cost.

[0008] Membrane filtration is the use of a nanopore membrane to filter and separate micron-sized impurities such as bacteria, oil-water emulsion microspheres, and dicarboxylate aqueous solution. The bacteria, oil-water emulsion microspheres, etc. remain on the concentrate side, and the dicarboxylate aqueous solution goes to the filtrate side. In this process, a large amount of high-concentration emulsions and bacteria continuously contaminate and clog the filtration channels during the filtration process, causing the membrane filtration rate to decay quickly, affecting the processing efficiency. The membrane filtration concentrate is a solid-liquid mixed system of high-concentration bacteria and oil-water emulsions. In order to recover alkanes, the concentrate needs to be further demulsified. The high solid content increases the difficulty of demulsification and reduces the recovery rate of alkanes. Summary of the invention

[0009] In view of the above shortcomings, the present invention provides a method for treating dicarboxylic acid fermentation broth, which controls demulsification by pH and temperature, has a simple and safe operation process, can be operated for a long time, and is easy for industrial-scale production.

[0010] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0011] A method for treating a dicarboxylic acid fermentation broth, comprising:

[0012] I. Adjusting the pH of the fermentation broth containing dicarboxylate to 5.0-7.0, and heating to 40-70° C. to obtain a fermentation broth containing dicarboxylate monosalt;

[0013] II. adding dicarboxylic acid monosalt to the fermentation liquid containing dicarboxylic acid monosalt and continuing to heat the fermentation liquid. III. separating and recovering the upper alkane after the fermentation liquid is demulsified, and the dicarboxylic acid monosalt filtrate obtained by solid-liquid separation of the lower solution containing dicarboxylic acid monosalt;

[0014] IV. Continue to add acid to the dicarboxylic acid monosalt filtrate obtained in III to acidify the dicarboxylic acid, and then crystallize the dicarboxylic acid. The dicarboxylic acid is obtained by filtering, washing and drying.

[0015] In the present invention, in step I, the pH of the fermentation liquid is adjusted to 5.0-7.0, preferably to 5.5-6.5, so that the dicarboxylic acid disalt of the fermentation liquid is converted into the dicarboxylic acid monosalt, thereby promoting the demulsification of the emulsion.

[0016] Furthermore, in step I, the fermentation liquid is preferably heated to 50-60° C. to accelerate the conversion rate of the double salt to the monosalt and simultaneously promote the movement of alkanes in the deep layer of the fermentation liquid to the liquid surface.

[0017] Furthermore, in step II, the method of heating the fermentation liquid is preferably achieved by adding hot water or steam to the upper layer of the fermentation liquid. This method can increase the temperature of the emulsion layer in a targeted manner, reduce energy consumption compared to the method of heating the fermentation liquid as a whole, and has a better demulsification effect. As a more preferred method, 80-100°C hot water or steam is added by spraying, preferably 95-100°C hot water or steam is added by spraying.

[0018] Furthermore, the volume of hot water added to the fermentation liquid is 1-10 times, preferably 2-5 times, that of the emulsified layer.

[0019] Furthermore, the dicarboxylic acid monosalt added in step II is added alone or first added to the hot water and then added to the fermentation broth, preferably mixed with hot water, wherein the weight concentration of the dicarboxylic acid monosalt is 1%-20%, preferably 6%-10%. By adding the dicarboxylic acid monosalt, the emulsion layer is demulsified faster.

[0020] Furthermore, the type of the dicarboxylic acid monosalt added in step II is consistent with the dicarboxylic acid to be purified in the fermentation broth.

[0021] Furthermore, when water or steam is added to the fermentation liquid, stirring is stopped to make the fermentation liquid static.

[0022] Furthermore, the solid-liquid separation method in step III includes but is not limited to flocculation sedimentation, microfiltration, ultrafiltration, centrifugation, pressure filtration, vacuum filtration, etc., to remove impurities such as bacteria to obtain a clarified dicarboxylic acid monosalt filtrate.

[0023] Furthermore, the acidification described in step IV is carried out by a method known in the prior art. Specifically, the pH value of the acidification is 2.0-4.0. The acid used for acidification is an inorganic acid or organic acid such as H2SO4, HNO3, HCl or H3PO4, formic acid, acetic acid, propionic acid, etc. of any concentration, and a clean acid or a recycled acid can be selected, and a single acid or a compound acid can be selected. The dicarboxylic acid crystallization is carried out by first heating the liquid and then cooling it, and the dicarboxylic acid crystallizes during the cooling process.

[0024] The implementation of the embodiments of the present invention has the following advantages:

[0025] (1) Treatment of dicarboxylic acid fermentation broth is a key step in the extraction technology of dicarboxylic acid primary products. In order to efficiently utilize alkanes to convert into dicarboxylic acids, alkanes are usually dispersed into an emulsified state during the fermentation process, which can improve the efficiency of alkanes entering the cell membrane and converting into dicarboxylic acids. The inventors found that the presence of alkane emulsion in the mature fermentation broth makes the separation process of bacteria and dicarboxylates more difficult, and solid-liquid separation is basically impossible to achieve. If the emulsion is not broken, the dicarboxylates in the emulsion cannot be released, which not only affects the product yield but also affects the product quality.

[0026] The inventor found in the study that by adding acid to the fermentation broth to adjust the pH to 5.0-7.0, the dicarboxylic acid disalt is converted into a monosalt, which can effectively promote the demulsification of the emulsion. The dicarboxylic acid disalt solution is alkaline, and when extracting dicarboxylic acid, it is necessary to add acid to convert the salt into dicarboxylic acid for precipitation. The present invention directly adds acid to the fermentation broth to adjust the pH value to 5.0-7.0, which will not increase the cost of acid, and promotes the demulsification of the emulsion. The inventor conducted in-depth research and found that the dicarboxylic acid monosalt, the carboxyl group connected to the long carbon chain is insoluble in water and weakly polar, has lipophilicity, and the carboxyl salt at the other end is easily soluble in water and is hydrophilic. It is inferred that the dicarboxylic acid monosalt is a surfactant that promotes demulsification, which can promote the demulsification and stratification of the dicarboxylic acid fermentation broth, and can efficiently recover alkanes and dicarboxylic acids in the emulsion.

[0027] (2) Heating is usually beneficial to demulsification. The inventors of this case have found that adding acid to adjust the pH and heating the fermentation liquid within a certain pH range can significantly accelerate the conversion rate of double salt to monosalt, and at the same time, it is observed that the demulsification time of the emulsion is significantly shortened. In addition, heating the entire fermentation liquid not only consumes more energy and increases costs, but also increases the probability of bacterial cell breakage and the protein released into the fermentation liquid. A preferred embodiment of the present invention is to spray hot water, preferably hot water containing a monosalt of a dicarboxylic acid, onto the emulsified layer, which can not only accelerate demulsification, but also save a lot of energy.

[0028] (3) The present invention adopts the operation of adjusting pH to generate dicarboxylic acid monosalt coupled with hot water spraying. Compared with the demulsification process such as adding demulsifier and alkalizing and heating, the present invention has the advantages of milder demulsification conditions, lower energy consumption, lower cost, etc., and the obtained dicarboxylic acid nitrogen content is less, which has industrial implementation value.

[0029] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0030] The following non-limiting embodiments may enable a person skilled in the art to more fully understand the present invention, but are not intended to limit the present invention in any way.

[0031] The following examples provide the demulsification and primary product extraction process of dicarboxylic acid fermentation broth, wherein the nitrogen content of the dicarboxylic acid primary product is detected using the GB5009.5-2016 method.

[0032] Example 1

[0033] I. Stir 100 liters of fermentation liquid containing decacarboxylic acid, add sulfuric acid to adjust the pH to 6.0, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0034] II. Stop stirring and spray 20 liters of a 95°C aqueous solution in which 10% of decacarboxylic acid monosodium salt is dissolved into the dicarboxylic acid monosalt fermentation liquid.

[0035] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0036] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain decacarboxylic acid.

[0037] The nitrogen content of the obtained decacarboxylic acid product is shown in Table 1.

[0038] Example 2

[0039] I. Stir 100 liters of fermentation liquid containing undecanedicarboxylic acid, add sulfuric acid to adjust the pH to 6.3, and heat to 58° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0040] II. Stop stirring and spray 20 liters of a 95°C aqueous solution in which 8% of undecanedicarboxylic acid monosodium salt is dissolved into the dicarboxylic acid monosalt fermentation liquid.

[0041] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0042] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain undecanedicarboxylic acid.

[0043] The nitrogen content of the obtained undecanedicarboxylic acid product is shown in Table 1.

[0044] Example 3

[0045] I. Stir 100 liters of fermentation liquid containing dodecanedicarboxylic acid, add sulfuric acid to adjust the pH to 6.3, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0046] II. Stop stirring and spray 25 liters of a 98°C aqueous solution in which 8% of monosodium dodecanedicarboxylate is dissolved into the dicarboxylic acid monosalt fermentation liquid.

[0047] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0048] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain dodecanedicarboxylic acid.

[0049] The nitrogen content of the obtained dodecanedicarboxylic acid product is shown in Table 1.

[0050] Example 4

[0051] I. Stir 100 liters of fermentation liquid containing tridecanedicarboxylic acid, add sulfuric acid to adjust the pH to 6.3, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0052] II. Stop stirring and spray 30 liters of a 97°C aqueous solution containing 6% sodium tridecanedicarboxylate dissolved therein into the dicarboxylic acid monosalt fermentation liquid.

[0053] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0054] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain tridecanedicarboxylic acid.

[0055] The nitrogen content of the obtained tridecanedicarboxylic acid product is shown in Table 1.

[0056] Example 5

[0057] I. Stir 100 liters of fermentation liquid containing tetradecanedicarboxylic acid, add sulfuric acid to adjust the pH to 6.5, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0058] II. Stop stirring and spray 35 liters of a 97°C aqueous solution in which 8% of tetradecanedicarboxylic acid monosodium salt is dissolved into the dicarboxylic acid monosalt fermentation liquid.

[0059] III. Separate and recover the upper layer of alkanes, and filter the lower layer of liquid to obtain the dicarboxylic acid monosalt filtrate.

[0060] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain tetradecanedicarboxylic acid.

[0061] The nitrogen content of the obtained tetradecanedicarboxylic acid product is shown in Table 1.

[0062] Example 6

[0063] I. Stir 100 liters of fermentation liquid containing 15-carbon dicarboxylic acid, add sulfuric acid to adjust the pH to 6.5, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0064] II. Stop stirring and spray 40 liters of a 97°C aqueous solution in which 10% of pentadecanedicarboxylic acid monosodium salt is dissolved into the dicarboxylic acid monosalt fermentation liquid.

[0065] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0066] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain pentadecanedicarboxylic acid.

[0067] The nitrogen content of the obtained 15-carbon dicarboxylic acid product is shown in Table 1.

[0068] Example 7

[0069] I. Stir 100 liters of fermentation liquid containing hexadecanedicarboxylic acid, add sulfuric acid to adjust the pH to 6.5, and heat to 60° C. to obtain dicarboxylic acid monosalt fermentation liquid.

[0070] II. Stop stirring and slowly inject 45 liters of 97°C aqueous solution in which 10% of hexadecanedicarboxylic acid monosodium salt is dissolved into the upper layer of the dicarboxylic acid monosalt fermentation liquid.

[0071] III. Separate and recover the upper alkane, and filter the lower liquid to obtain the dicarboxylate filtrate.

[0072] IV. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain hexadecanedicarboxylic acid.

[0073] The nitrogen content of the obtained hexadecanedicarboxylic acid product is shown in Table 1.

[0074] Comparative Example 1

[0075] I. Filter 1 liter of fermentation broth containing dodecanedicarboxylic acid, add 10 g of urea, and heat to 98°C.

[0076] II. Slowly cool to 20°C, let stand for 1 hour, then separate and recover the unreacted alkane, and filter the lower layer of dodecanedicarboxylic acid solution.

[0077] III. Add sulfuric acid to the dicarboxylate filtrate, adjust the pH to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain dodecanedicarboxylic acid.

[0078] The nitrogen content of the obtained dodecanedicarboxylic acid product is shown in Table 1.

[0079] Comparative Example 2

[0080] I. Add 98% sulfuric acid to 1 liter of fermentation broth containing dodecanedicarboxylic acid to acidify the pH to 4.0.

[0081] II. Filter, wash and dry the acidified solution obtained in the previous step to obtain dodecanedicarboxylic acid.

[0082] The nitrogen content of the obtained dodecanedicarboxylic acid product is shown in Table 1.

[0083] Comparative Example 3

[0084] I. Heat 10 liters of fermentation broth containing dodecanedicarboxylic acid to 95°C and keep warm for 30 minutes.

[0085] II. The above feed liquid is filtered through a ceramic membrane to obtain a filtrate.

[0086] III. Add sulfuric acid to the filtrate of dodecanedicarboxylate, adjust the pH value to 4.0, heat to 95° C., then cool to room temperature, filter, wash and dry to obtain dodecanedicarboxylic acid.

[0087] The nitrogen content of the obtained dodecanedicarboxylic acid product is shown in Table 1.

[0088] Comparative Example 4

[0089] Except for not carrying out step II, the other steps are the same as those in Example 3. The nitrogen content of the obtained dodecanedicarboxylic acid product is shown in Table 1.

[0090] Table 1.

[0091]

Claims

1. A method for treating a dicarboxylic acid fermentation broth, comprising: I. Adjusting the pH of the fermentation broth containing dicarboxylate to 5.0-7.0, and heating to 40-70° C. to obtain a fermentation broth containing dicarboxylate monosalt; II. Adding dicarboxylic acid monosalt to the fermentation broth containing dicarboxylic acid monosalt and continuing to heat the fermentation broth III. Separating and recovering the upper alkane after the fermentation liquid is demulsified, and performing solid-liquid separation on the lower layer of the solution containing the dicarboxylic acid monosalt to obtain the dicarboxylic acid monosalt filtrate; IV. Continue to add acid to the dicarboxylic acid monosalt filtrate obtained in III to acidify the dicarboxylic acid so that the dicarboxylic acid crystals are precipitated, and then filter, wash and dry to obtain the dicarboxylic acid.

2. The processing method according to claim 1, characterized in that: In step I, the pH of the fermentation broth is adjusted to 5.5-6.

5.

3. The processing method according to claim 2, characterized in that: In step I, the fermentation broth is heated to 50-60°C.

4. The processing method according to claim 1, characterized in that: In step II, the fermentation liquid is heated by adding hot water or steam to the upper layer of the fermentation liquid.

5. The processing method according to claim 4, characterized in that: In step II, the fermentation liquid is heated by adding 80-100° C. hot water or steam in a spraying manner.

6. The processing method according to claim 5, characterized in that: The volume of hot water added to the fermentation broth is 1-10 times that of the emulsion layer.

7. The processing method according to claim 6, characterized in that: The dicarboxylic acid monosalt added in step II is mixed with hot water and added, wherein the weight concentration of the dicarboxylic acid monosalt is 1%-20%.

8. The processing method according to claim 4, characterized in that: When adding water or steam to the fermentation liquid, stop stirring and allow the fermentation liquid to be static.

9. The processing method according to claim 1, characterized in that: The solid-liquid separation method in step III is selected from one or a combination of flocculation sedimentation, microfiltration, ultrafiltration, centrifugation, pressure filtration and vacuum filtration.

10. The processing method according to claim 1, characterized in that: The dicarboxylic acid crystallization in step IV is carried out by first heating the liquid and then cooling it, and the dicarboxylic acid crystallization is precipitated during the cooling process.

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