A method for treating glutamic acid fermentation wastewater

Abstract

The present application belongs to the technical field of wastewater treatment, and discloses a method for treating glutamic acid fermentation wastewater, which comprises the following steps: mixing bacillus subtilis inoculum and brevitux inoculum uniformly to obtain a compound inoculum, adding the compound inoculum into the glutamic acid fermentation wastewater, and treating for more than 24 hours. The method uses high-efficiency inoculum, has simple compatibility, requires a small amount of use, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically discloses a method for treating glutamic acid fermentation wastewater. Background Technology

[0002] Fermentation is the main method for producing glutamic acid. After separation and purification, glutamic acid yields the product, generating a large amount of fermentation wastewater. This wastewater is characterized by "five highs and one low": high COD, high BOD5, high bacterial count, high sulfate (formerly chloride ion before pH adjustment with sulfuric acid), high ammonia nitrogen, and low pH (1.5-3.2). It is a highly difficult industrial wastewater to treat. Due to the inability to effectively treat monosodium glutamate (MSG) wastewater, many MSG factories have been listed as key pollution sources nationwide. The treatment of MSG wastewater has become a major problem restricting the development of MSG production enterprises. Treatment technologies for this high-concentration organic industrial wastewater have always been a research hotspot and a challenge.

[0003] The applicant has conducted extensive research on the remediation and treatment of amino acid fermentation wastewater. Microbial inoculant treatment is the most economical and environmentally friendly method, but it also has the following shortcomings: First, the effect of a single strain is poor, but it is difficult to combine multiple inoculants. Finding strains that can coexist and exert synergistic effects requires a lot of experiments; Second, the excessive number of strains in the inoculant increases the possibility of strain contamination and also increases the cost and procedures of cultivating bacteria; Third, the inoculant includes adsorbent carriers and bacteria, and the amount used is too large, which easily causes sedimentation at the bottom of the tank, resulting in flocculation and the generation of a large amount of sludge, which is difficult to clean.

[0004] CN115927073A discloses a heterotrophic nitrifying bacterium, *Pseudomonas stutzeri* SKS-22-1, capable of synergistic removal of ammonia nitrogen and pesticide residues. This strain is deposited at the Guangdong Provincial Microbial Culture Collection Center (GDMCC) under accession number No. 62696 and was isolated from riverbed sludge. The *P. stutzeri* SKS-22-1 preparation was inoculated into farmland drainage containing pesticide residues for rapid ammonia nitrogen removal. However, experiments showed that this single strain had poor treatment efficacy against glutamate fermentation wastewater.

[0005] CN105833832A discloses a biochemical preparation for treating glutamic acid fermentation wastewater, comprising a physical adsorbent and a composite microbial preparation. The composite microbial preparation comprises the following raw materials in parts by weight: 6-8 parts of *Azotobacter chroococcus*, 4-6 parts of *Rhodococcus*, 4-6 parts of *Bacillus amyloliquefaciens*, 3-5 parts of *Clostridium papillosum*, 3-5 parts of *Penicillium ochraceus*, 3-4 parts of *Pseudomonas*, and 2-3 parts of *Bacillus cereus*. It contains multiple microorganisms with excellent degradation capabilities for recalcitrant pollutants. However, this preparation contains too many strains, increasing the possibility of strain contamination and increasing the cost and procedures of cultivating the bacteria.

[0006] Developing a microbial agent for treating and managing glutamic acid fermentation wastewater to reduce wastewater pollution and turn waste into a valuable resource is a pressing technical problem that needs to be solved in this field. Summary of the Invention

[0007] The purpose of this invention is to address the shortcomings of traditional processes by providing a method for treating glutamic acid fermentation wastewater. This method uses highly efficient microbial agents, is simple to formulate, requires a small amount, and has broad application prospects.

[0008] The present invention is achieved through the following technical solution.

[0009] A method for treating glutamic acid fermentation wastewater includes the following steps:

[0010] A compound bacterial agent was prepared by mixing Bacillus subtilis inoculant and Bacillus flavus inoculant, and then added to the glutamic acid fermentation wastewater for treatment for more than 24 hours.

[0011] Furthermore,

[0012] The preparation method of the Bacillus subtilis inoculant includes:

[0013] 1) Transfer the Bacillus subtilis seed culture into the fermentation medium and culture it. When the cell concentration reaches OD600=15, stop the fermentation to obtain Bacillus subtilis fermentation broth.

[0014] 2) Take the Bacillus subtilis fermentation broth, centrifuge to remove the supernatant, add an equal weight of adsorbent carrier and mix, then dry the mixed material to obtain the final product.

[0015] Furthermore,

[0016] The fermentation medium consists of: molasses 40 g / L, corn steep liquor 10 g / L, ammonium sulfate 10 g / L, urea 6 g / L, soybean meal 2 g / L, and wheat bran 2 g / L.

[0017] Furthermore,

[0018] The preparation method of the *Bacillus flavovirens* inoculum includes:

[0019] 1) Transfer the seed culture of *Bacillus flavus* into a fermentation medium and culture it. When the cell concentration reaches OD600 = 12, stop the fermentation to obtain the fermentation broth of *Bacillus flavus*.

[0020] 2) Take the fermentation broth of *Bacillus flavovirens*, centrifuge to remove the supernatant, add an equal weight of adsorbent carrier and mix, then dry the mixed material to obtain the final product.

[0021] Furthermore,

[0022] The fermentation medium consists of: molasses 40 g / L, corn steep liquor 15 g / L, ammonium sulfate 10 g / L, wheat bran 2 g / L, and KH2PO4 1 g / L.

[0023] Preferably,

[0024] The Bacillus subtilis used was Bacillus subtilis CGMCC No. 23581.

[0025] Preferably,

[0026] The selected strain of *Syntrophus flavus* is *Syntrophus flavus* CGMCC No. 27546.

[0027] Preferably,

[0028] The processing time is 48 hours.

[0029] Preferably,

[0030] The amount of the compound microbial agent added is more than 100g per ton of glutamic acid fermentation wastewater.

[0031] More preferably,

[0032] The dosage of the compound microbial agent is 200g per ton of glutamic acid fermentation wastewater. Detailed Implementation

[0033] To enable those skilled in the art to better understand the technical solutions in this application, the present invention will be described more clearly and completely below in conjunction with specific embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0034] Example 1

[0035] It is known that Bacillus subtilis has a certain ability to degrade pollutants in wastewater. This invention compares the performance of several Bacillus subtilis strains.

[0036] The specific strains of Bacillus subtilis selected are as follows: Bacillus subtilis CGMCC No. 23581, Bacillus subtilis CGMCC 1.1630, Bacillus subtilis CGMCC No. 0954, Bacillus subtilis ACCC04178, and Bacillus subtilis ATCC9372; the above strains were obtained through laboratory preservation or purchase.

[0037] Preparation of Bacillus subtilis inoculant:

[0038] 1) Obtain Bacillus subtilis seed culture through conventional culture. Transfer the above-mentioned Bacillus subtilis seed culture (OD600nm=2) into a fermenter containing fermentation medium at an inoculation rate of 10%. The pH value is 7.0, the temperature is 37℃, the pressure is 0.05MPa, and the dissolved oxygen is controlled at 10%. When the bacterial concentration reaches OD600=15, the fermentation is stopped to obtain Bacillus subtilis fermentation broth. The components of the fermentation medium are: molasses 40g / L, corn steep liquor 10g / L, ammonium sulfate 10g / L, urea 6g / L, soybean meal 2g / L, and wheat bran 2g / L.

[0039] 2) Take the Bacillus subtilis fermentation broth, centrifuge at 3000 rpm for 5 min, remove the supernatant, add an equal weight of bentonite and mix, dry the mixed material at 30℃ until the moisture content is 20%, and you will get the product.

[0040] Example 2

[0041] Artificially simulated glutamic acid fermentation wastewater was prepared with COD 2100 mg / L and ammonia nitrogen 500 mg / L.

[0042] Add Bacillus subtilis inoculant to the fermentation wastewater at concentrations of low (20g per ton of wastewater), medium (100g per ton of wastewater), and high (500g per ton of wastewater). Treat for 48 hours and then test for pollutant indicators. Specific parameters are shown in Tables 1-3.

[0043] Table 1 (Low Concentration)

[0044] strain type COD mg / L ammonia nitrogen mg / L CGMCC No. 23581 626 165 CGMCC 1.1630 1157 226 CGMCC No. 0954 579 197 ACCC04178 864 246 ATCC9372 1421 379

[0045] Table 2 (Medium Concentration)

[0046] strain type COD mg / L ammonia nitrogen mg / L CGMCC No. 23581 189 76 CGMCC 1.1630 731 148 CGMCC No. 0954 362 127 ACCC04178 298 205 ATCC9372 545 230

[0047] Table 3 (High Concentration)

[0048] strain type COD mg / L ammonia nitrogen mg / L CGMCC No. 23581 167 71 CGMCC 1.1630 558 122 CGMCC No. 0954 271 98 ACCC04178 219 147 ATCC9372 432 206

[0049] As can be seen from Table 1-3 above, the CGMCC No.23581 strain has a significantly better ability to degrade pollutants than other Bacillus subtilis strains.

[0050] Example 3

[0051] The *Bacillus flavus* CGMCC No. 27546 is a high-yield valine strain obtained by the applicant through mutagenesis. To verify other properties of this strain, an artificially simulated glutamic acid fermentation wastewater (COD 2100 mg / L, ammonia nitrogen 500 mg / L) was used to determine whether it has the ability to degrade pollutants.

[0052] Preparation of *Bacillus flavovirens* inoculum:

[0053] 1) Obtain the seed culture of *Bacillus flavus* through conventional culture. Transfer the seed culture (OD600nm=2) at an inoculation rate of 10% into a fermenter containing fermentation medium and culture at pH 6.7, temperature 36℃, pressure 0.04MPa, and dissolved oxygen controlled at 15%. Stop fermentation when the cell concentration reaches OD600=12 to obtain the fermentation broth of *Bacillus flavus*. The fermentation medium consists of: molasses 40g / L, corn steep liquor 15g / L, ammonium sulfate 10g / L, wheat bran 2g / L, and KH2PO4 1g / L.

[0054] 2) Take the fermentation broth of *Bacillus flavovirens*, centrifuge at 3000 rpm for 5 min, remove the supernatant, add an equal weight of bentonite and mix, dry the mixed material at 30℃ until the moisture content is 20%, and you will get the product.

[0055] Adding *Bacillus flavonoids* to artificially simulated fermentation wastewater at low, medium, and high concentrations (20g / ton of wastewater, 100g / ton of wastewater, and 500g / ton of wastewater) for 48 hours revealed that the low concentration had little impact on various pollutant indicators, the medium concentration reduced COD by approximately 5% and ammonia nitrogen by 8%, and the difference between the high and medium concentrations was minimal.

[0056] Example 4

[0057] The ability of Bacillus subtilis and Bacillus flavus to degrade pollutants was determined by artificially simulating the fermentation wastewater (COD 2100 mg / L, ammonia nitrogen 500 mg / L).

[0058] The treatment process is as follows: Bacillus subtilis inoculant (Example 1) and Bacillus flavus inoculant (Example 3) are mixed in equal mass ratio to obtain a compound inoculant. Then, 200g of the compound inoculant is added per ton of wastewater, and the treatment is carried out for 48 hours. See Table 4 for details.

[0059] Table 4

[0060]

[0061]

[0062] Example 5

[0063] Treatment of glutamic acid fermentation wastewater.

[0064] Take the glutamic acid fermentation wastewater from Fufeng's production workshop as an example (COD is 2321 mg / L, ammonia nitrogen is 517 mg / L, and sulfide is 106 mg / L).

[0065] The treatment process is as follows: Bacillus subtilis inoculant (prepared according to Example 1) and Bacillus flavus inoculant (prepared according to Example 3) are mixed in equal mass ratio to obtain a compound inoculant. Then, 200g of the compound inoculant is added per ton of wastewater, and the treatment lasts for 48 hours. See Table 5 for details.

[0066] Table 5

[0067]

[0068] As shown in Table 5 above, the performance of *Bacillus flavus* CGMCC No. 27546 in treating pollutants in wastewater varies greatly when used in combination with different strains of *Bacillus subtilis*. Specifically, *Bacillus subtilis* CGMCC No. 23581 and *Bacillus flavus* CGMCC No. 27546 work together to degrade pollutants in wastewater, exhibiting a symbiotic and synergistic relationship. However, other *Bacillus subtilis* strains do not show a significant symbiotic and synergistic effect when combined with *Bacillus flavus* CGMCC No. 27546, and are not suitable for use as a compound bacterial agent. This demonstrates that even strains of the same species can exhibit significant differences in certain aspects of their performance.

[0069] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for treating glutamic acid fermentation wastewater, comprising the following steps: A compound bacterial agent was prepared by mixing Bacillus subtilis inoculum and Bacillus flavus inoculum in an equal mass ratio and adding it to the glutamic acid fermentation wastewater for treatment for more than 24 hours. The preparation method of the Bacillus subtilis inoculant includes: 1) Transfer the Bacillus subtilis seed culture into the fermentation medium and culture it. When the cell concentration reaches OD600=15, stop the fermentation to obtain Bacillus subtilis fermentation broth. 2) Take the Bacillus subtilis fermentation broth, centrifuge to remove the supernatant, then add an equal weight of adsorbent carrier and mix. Dry the mixed material to obtain the final product. The Bacillus subtilis strain is Bacillus subtilis CGMCC No. 23581; The preparation method of the *Bacillus flavovirens* inoculum includes: 1) Transfer the seed culture of *Bacillus flavus* into a fermentation medium and culture it. When the cell concentration reaches OD600 = 12, stop the fermentation to obtain the fermentation broth of *Bacillus flavus*. 2) Take the fermentation broth of *Bacillus flavus*, centrifuge to remove the supernatant, then add an equal weight of adsorption carrier and mix. Dry the mixed material to obtain the final product; the *Bacillus flavus* is *Bacillus flavus* CGMCC No. 27546. The amount of the compound microbial agent added is more than 100g per ton of glutamic acid fermentation wastewater.

2. The method according to claim 1, characterized in that, The components of the Bacillus subtilis fermentation medium are: molasses 40 g / L, corn steep liquor 10 g / L, ammonium sulfate 10 g / L, urea 6 g / L, soybean meal 2 g / L, and wheat bran 2 g / L.

3. The method according to claim 1, characterized in that, The fermentation medium for *Bacillus flavus* consists of the following components: molasses 40 g / L, corn steep liquor 15 g / L, ammonium sulfate 10 g / L, wheat bran 2 g / L, and KH2PO4 1 g / L.

4. The method according to claim 1, characterized in that, The processing time is 48 hours.

5. The method according to any one of claims 1-4, characterized in that, The dosage of the compound microbial agent is 200g per ton of glutamic acid fermentation wastewater.

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