A biological treatment method for high-concentration DMF wastewater

Abstract

The present application relates to a kind of high concentration DMF waste water biological treatment method, belong to wastewater treatment technical field;Including: mixed strain screening, activation and scale-up culture are carried out;And join DMF waste water;In fermentation treatment, the growth of microorganism and the change situation of COD are monitored regularly, when microorganism growth is in logarithmic phase, extract microbial genomic DNA, high-throughput sequencing is carried out to microorganism in fermentation waste water, determine the proportion of final fermentation waste water and dominant genus;When mixed strain processing efficiency reduces in fermentation process, add certain genus according to genus proportion to make its proportion consistent, and add carbon source and growth factor;Compared with single bacteria degradation DMF, the mixed strain selected by the present application converts DMF in waste water into dimethylamine and methylamine by the process of mixed strain biological fermentation, and is finally converted into ammonia and carbon dioxide, and the biochemical property can be increased by 2-5 times, to reduce the load of subsequent conventional sludge system.

Description

Technical Field

[0001] The invention relates to a biological treatment method for high-concentration DMF wastewater, belonging to the technical field of wastewater treatment. Background Art

[0002] N,N-Dimethylformamide (DMF) boasts a high boiling point, low freezing point, and excellent chemical and thermal stability. It is an excellent organic solvent and fine chemical raw material, widely used in many industries, such as chemicals, pharmaceuticals, and textiles. Known as a "universal solvent," DMF is miscible with water and a variety of organic solvents. At room temperature, it is completely miscible with water, ethers, alcohols, ketones, esters, chlorinated hydrocarbons, aromatic hydrocarbons, and other organic compounds. However, DMF production and application processes generate DMF wastewater, which is highly toxic, difficult to degrade, and poses a significant threat to the environment.

[0003] Currently, DMF wastewater treatment primarily involves physical, chemical, and biological methods. Physical methods for treating DMF-containing wastewater primarily include distillation, extraction, and adsorption. These methods are often used to treat wastewater with high DMF content while also achieving recovery and reuse. However, these methods require high energy consumption and equipment investment. Chemical methods for treating DMF-containing wastewater primarily include alkaline hydrolysis, Fenton oxidation, photocatalytic oxidation, and supercritical water oxidation. These methods are generally used to treat wastewater containing medium to low concentrations of DMF. Compared to physical and chemical methods, biological treatment offers advantages such as environmental friendliness, mild conditions, resource conservation, non-toxic decomposition products, and the ability to achieve a virtuous cycle of substances. Even after DMF wastewater is recovered and reused, a small amount of DMF may still remain. Using physical and chemical methods would significantly increase costs. In this case, biological pretreatment can not only degrade DMF into non-toxic substances but also improve the biodegradability of the wastewater. Therefore, it is necessary to develop suitable, efficient, and low-cost treatment methods for residual DMF in wastewater. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies in the prior art and provide a biological treatment method for high-concentration DMF wastewater, which uses bacteria to treat high-concentration DMF wastewater to achieve high efficiency, low cost and environmentally friendly effects.

[0005] In order to achieve the above object, the present invention is achieved by the following technical solutions: a biological treatment method for high-concentration DMF wastewater, the method is as follows:

[0006] Step S1: sampling around the chemical plant;

[0007] Step S2: preparing enrichment culture medium with different concentrations of DMF as the sole carbon and nitrogen source, treating the sample obtained in step S1 and then adding it to the culture medium for culturing;

[0008] Step S3: When the OD600nm When the maximum value is reached, the concentration of DMF is detected;

[0009] Step S4: When the DMF degradation rate reaches 90%, high-throughput sequencing is performed to obtain the bacterial species composition; when the DMF degradation rate is less than 50%, a carbon source is added; when the DMF degradation rate increases to more than 80%, high-throughput sequencing is performed to obtain the bacterial species composition;

[0010] Step S5: preserving the mixed bacterial strain with a DMF degradation rate of 80%-90% in step S4, preparing cryovials containing 20% ​​glycerol and storing them at -80°C;

[0011] Step S6: activating and expanding the mixed bacterial strain cryopreservation tube in step S5;

[0012] Step S7: adding the mixed strains in step S6 to the high-concentration DMF wastewater for biological fermentation pretreatment;

[0013] Step S8: During the fermentation process, the growth of the microorganisms and the changes in COD are regularly monitored. When the microorganisms are in the logarithmic growth phase, the microorganism genomic DNA is extracted and high-throughput sequencing is performed on the microorganisms in the fermentation wastewater to determine the proportion of bacterial genera and the dominant bacterial genera in the final fermentation wastewater;

[0014] Step S9: During the fermentation process, when the treatment efficiency of the mixed bacterial community decreases, a certain bacterial genus is added according to the bacterial genus ratio in step S8 to make the ratio consistent, and a carbon source and growth factors required for growth are added.

[0015] Preferably, the enrichment culture medium with DMF as the sole carbon and nitrogen source at different concentrations as described in step S2 is an enrichment culture medium with DMF as the sole carbon and nitrogen source at concentrations of 0.5%, 1%, 1.5%, 2%, 2.5%, and 3%.

[0016] Preferably, the culture conditions in step S2 are specifically: culture at 30° C. and pH 7.

[0017] Preferably, the mixed microorganisms in step S5 include Paracoccus, Pseudomonas, Alcaligenes, Ochrobacturm, and Bacillus.

[0018] Preferably, the carbon source in step S4 and the carbon source in step S9 include glucose and starch. Adding other carbon sources such as glucose and starch during the mixed strain screening process improves the biodegradability of DMF, helps DMF-degrading bacteria form biofilms, and thus improves the degradation rate of DMF.

[0019] Preferably, the ratio of biodegradable organic carbon to total organic carbon in the high-concentration DMF wastewater described in step S7 is greater than 50%, B / C>0.3, COD is 10,000-30,000 mg / L, and DMF concentration is 500-3,500 mg / L.

[0020] Preferably, in step S7, the fermentation system is fed with water intermittently at a low load in the early stage, and then fed with water continuously at a high load in the later stage. The intermittent feeding at a low load in the early stage allows the wastewater and the mixed bacteria to be fully mixed; then the high load is continued continuously, and the impact force of the high load is used to fully biochemically treat the wastewater.

[0021] Preferably, before adding the mixed bacterial strains in step S7, urea and phosphate are added to make the molar ratio of C:N:P in the wastewater equal to 190-210:4-6:1.

[0022] Preferably, the composition of the mixed microorganisms in step S8 is 25-36% Paracoccus genus, 23-30% Pseudomonas genus, 18-22% Alcaligenes genus, 15-20% Ochrobacturm genus, 10-15% Bacillus genus and others <5%.

[0023] Preferably, the growth factors in step S9 are vitamins, biotin and trace elements.

[0024] The present invention has the following beneficial effects: (1) The present invention performs sampling under special conditions, screens mixed bacterial strains in a targeted manner, and provides mixed bacterial strains with strong specificity and good effects for biological pretreatment, especially for wastewater with high DMF content.

[0025] (2) Compared with single bacteria for degrading DMF, the mixed strain selected in the present invention converts DMF in wastewater into dimethylamine and methylamine through the mixed strain biological fermentation process, and finally converts it into ammonia and carbon dioxide, which can improve the biodegradability by 2-5 times, and removes 60%-90% of COD and ammonia nitrogen in the wastewater, reducing the load of the subsequent conventional sludge system and improving the treatment efficiency of the subsequent conventional sludge system. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The changes in DMF in the last week before and after wastewater treatment in Example 1 are shown;

[0027] Figure 2 It is the bacterial genus ratio after the system in Example 1 is stably operated. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the examples, but they are not intended to limit the present invention.

[0029] A biological treatment method for high-concentration DMF wastewater, said method is as follows:

[0030] Step S1: sampling around the chemical plant;

[0031] Step S2: preparing 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% enrichment culture medium with DMF as the sole carbon and nitrogen source, adding the processed sample obtained in step S1 to the culture medium, and culturing at 30° C. and pH 7;

[0032] Step S3: When the OD 600nm When the maximum value is reached, the concentration of DMF is detected;

[0033] Step S4: When the DMF degradation rate reaches 90%, high-throughput sequencing is performed to obtain the bacterial species composition; when the DMF degradation rate is less than 50%, glucose and starch carbon sources are added; when the DMF degradation rate increases to more than 80%, high-throughput sequencing is performed to obtain the bacterial species composition;

[0034] Step S5: preserving the mixed bacterial strains with a DMF degradation rate of 80%-90% in step S4, preparing cryovials containing 20% ​​glycerol and storing them at -80°C; the mixed bacterial strains include the genera Paracoccus, Pseudomonas, Alcaligenes, Ochrobacturm, and Bacillus;

[0035] Step S6: activating and expanding the mixed bacterial strain cryopreservation tube in step S5;

[0036] Step S7: adding the mixed strains in step S6 to the high-concentration DMF wastewater for biological fermentation pretreatment;

[0037] Step S8: During the fermentation process, the growth of the microorganisms and the changes in COD are regularly monitored. When the microorganisms are in the logarithmic growth phase, the microorganism genomic DNA is extracted and high-throughput sequencing is performed on the microorganisms in the fermentation wastewater to determine the proportion of bacterial genera and the dominant bacterial genera in the final fermentation wastewater;

[0038] Step S9: During the fermentation process, when the mixed bacterial community treatment efficiency decreases, a certain type of bacterial genus is added according to the bacterial genus ratio in step S8 to make the ratio consistent, and microbial glucose, starch carbon source and growth factors required for growth are added to optimize the effect; the growth factors are vitamins, biotin and trace elements.

[0039] Furthermore, in the high-concentration DMF wastewater of step S7, the ratio of biodegradable organic carbon to total organic carbon is greater than 50%, B / C>0.3, COD is between 10,000 and 30,000 mg / L, and the DMF concentration is between 500 and 3,500 mg / L;

[0040] In step S7, water is fed intermittently at a low load in the early stage of the fermentation system, and then water is fed continuously at a high load in the later stage.

[0041] Before adding the mixed bacterial strains in step S7, urea and phosphate are added to make the molar ratio of C:N:P in the wastewater equal to 190-210:4-6:1;

[0042] The composition of the mixed microorganisms in step S8 is 25-36% Paracoccus genus, 23-30% Pseudomonas genus, 18-22% Alcaligenes genus, 15-20% Ochrobacturm genus, 10-15% Bacillus genus and others <5%.

[0043] Example 1: Biological pretreatment of pharmaceutical wastewater from a Zhejiang enterprise

[0044] Wastewater quality analysis: High-concentration wastewater contains difficult-to-degrade toxic substances such as dimethylformamide (DMF) and tetrahydrofuran. This type of wastewater cannot be directly fed into the company's existing conventional sludge system, limiting the company's production capacity. Water quality information is as follows:

[0045] Water quality indicators COD <![CDATA[NH3-N]]> TP content 15000mg / L 350mg / L 2mg / L

[0046] The specific method is:

[0047] C1: Activate the frozen tube of the mixed bacteria and expand the culture;

[0048] C2: adding the above mixed strains to DMF wastewater, adding urea and phosphate to make the molar ratio of C:N:P in the wastewater = 190:5:1, and performing biological fermentation pretreatment; the fermentation system is first fed intermittently at a low load in the early stage, and then continuously fed at a high load in the later stage;

[0049] C3: During the fermentation process, the growth of microorganisms and the changes in COD were monitored regularly. When the microorganisms were in the logarithmic growth phase, the microbial genomic DNA was extracted and high-throughput sequencing was performed on the microorganisms in the fermentation wastewater to determine the proportion of bacterial genus and the dominant bacterial genus in the final fermentation wastewater (see Figure 2); the dominant genera are the top four genera in terms of proportion: Paracoccus (26.31%), Pseudomonas (24.22%), Alcaligenes (19.86%), and Bacillus (17.43%), with the combined abundance of these dominant genera exceeding 80%. C4: During the fermentation process, when the mixed bacterial community processing efficiency decreases, certain genera are added to the proportions in C3 to maintain a consistent ratio. Carbon sources such as glucose and starch, as well as growth factors required for microbial growth, are also added to optimize the effect.

[0050] The main indicators after treatment are as follows: the overall stay time is several days. Figure 1 As shown in the figure (the horizontal axis is the number of operating days, and the vertical axis is the DMF content in %), the DMF removal rate in the wastewater is over 90%, the COD removal rate is over 65%, and the total nitrogen removal rate is over 70%. The entire biological pretreatment system operates stably, which greatly improves the treatment efficiency of the subsequent system and increases the capacity of the entire sewage treatment system by more than 50%.

[0051] Example 2

[0052] Wastewater quality analysis: High-concentration wastewater contains difficult-to-degrade toxic substances such as dimethylformamide (DMF) and tetrahydrofuran. The water quality information is as follows:

[0053] Water quality indicators COD <![CDATA[NH3-N]]> TP content 18000mg / L 350mg / L 2.4mg / L

[0054] The specific method is:

[0055] C1: Activate the frozen tube of the mixed bacteria and expand the culture;

[0056] C2: adding the above mixed strains to DMF wastewater, adding urea and phosphate to make the molar ratio of C:N:P in the wastewater = 210:6:1, and performing biological fermentation pretreatment; the fermentation system is first fed intermittently at a low load in the early stage, and then continuously fed at a high load in the later stage;

[0057] C3: During the fermentation process, the growth of microorganisms and the changes in COD are monitored regularly. When the microbial growth is in the logarithmic phase, the microbial genomic DNA is extracted, and the microorganisms in the fermentation wastewater are subjected to high-throughput sequencing to determine the proportion of bacterial genera and the dominant genera in the final fermentation wastewater; the dominant genera are the top three genera ranked in terms of proportion, namely Paracoccus (26.74%), Alcaligenes (23.86%), and Ochrobacturm (28.45%), and the total abundance of the dominant genera exceeds 70%.

[0058] C4: During the fermentation process, when the treatment efficiency of the mixed bacterial community decreases, a certain type of bacterial genus is added according to the bacterial genus ratio in C3 to make the ratio consistent, and carbon sources such as microbial glucose and starch and growth factors required for growth are added to optimize the effect.

[0059] The main indicators after treatment are as follows: after a total stay of several days, the DMF removal rate in the wastewater reaches more than 99%, the COD removal rate reaches more than 80%, and the total nitrogen removal rate reaches more than 80%. The entire biological pretreatment system operates stably, which greatly improves the treatment efficiency of subsequent systems and increases the capacity of the entire sewage treatment system by more than 60%.

[0060] Example 3

[0061] Wastewater quality analysis: High-concentration wastewater contains difficult-to-degrade toxic substances such as dimethylformamide (DMF) and tetrahydrofuran. The water quality information is as follows:

[0062] Water quality indicators COD <![CDATA[NH3-N]]> TP content 20000mg / L 400mg / L 3mg / L

[0063] The specific method is:

[0064] C1: Activate the frozen tube of the mixed bacteria and expand the culture;

[0065] C2: adding the above mixed strains to DMF wastewater, adding urea and phosphate to make the molar ratio of C:N:P in the wastewater = 190:5:1, and performing biological fermentation pretreatment; the fermentation system is first fed intermittently at a low load in the early stage, and then continuously fed at a high load in the later stage;

[0066] C3: During the fermentation process, the growth of microorganisms and the changes in COD are monitored regularly. When the microbial growth is in the logarithmic phase, the microbial genomic DNA is extracted, and the microorganisms in the fermentation wastewater are subjected to high-throughput sequencing to determine the bacterial genus ratio and dominant genera in the final fermentation wastewater; the dominant genera are the top three genera ranked in terms of proportion, namely Paracoccus (26.35%), Pseudomonas (23.48%), and Alcaligenes (18.49%), and the total abundance of the dominant genera exceeds 60%.

[0067] C4: During the fermentation process, when the treatment efficiency of the mixed bacterial community decreases, a certain type of bacterial genus is added according to the bacterial genus ratio in C3 to make the ratio consistent, and carbon sources such as microbial glucose and starch and growth factors required for growth are added to optimize the effect.

[0068] The main indicators after treatment are as follows: after a total stay of several days, the DMF removal rate in the wastewater reaches more than 95%, the COD removal rate reaches more than 60%, the total nitrogen removal rate reaches more than 60%, and the entire biological pretreatment system operates stably, which greatly improves the treatment efficiency of the subsequent system and increases the capacity of the entire sewage treatment system by more than 40%.

[0069] The above shows and describes the basic principles, main features, and advantages of the present invention. However, the above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other implementation methods derived by any person skilled in the art without departing from the technical solution of the present invention should be included in the patent scope of the present invention.

Claims

1. A biological treatment method for high-concentration DMF wastewater, characterized in that, The method is as follows: Step S1: sampling around the chemical plant; Step S2: preparing enrichment culture medium with different concentrations of DMF as the sole carbon and nitrogen source, treating the sample obtained in step S1 and then adding it to the culture medium for cultivation; Step S3: When the OD 600nm When the maximum value is reached, the concentration of DMF is detected; Step S4: When the DMF degradation rate reaches 90%, high-throughput sequencing is performed to obtain the bacterial species composition; when the DMF degradation rate is less than 50%, a carbon source is added; when the DMF degradation rate increases to more than 80%, high-throughput sequencing is performed to obtain the bacterial species composition; Step S5: preserving the mixed bacterial strain with a DMF degradation rate of 80%-90% in step S4, preparing cryovials containing 20% ​​glycerol and storing them at -80°C; Step S6: activating and expanding the mixed bacterial strain cryopreservation tube in step S5; Step S7: adding the mixed strains in step S6 to the high-concentration DMF wastewater for biological fermentation pretreatment; Step S8: During the fermentation process, the growth of the microorganisms and the changes in COD are regularly monitored. When the microorganisms are in the logarithmic growth phase, the microorganism genomic DNA is extracted and high-throughput sequencing is performed on the microorganisms in the fermentation wastewater to determine the proportion of bacterial genera and the dominant bacterial genera in the final fermentation wastewater; Step S9: During the fermentation process, when the treatment efficiency of the mixed bacterial community decreases, a certain bacterial genus is added according to the bacterial genus ratio in step S8 to make the ratio consistent, and a carbon source and growth factors required for growth are added.

2. a biological treatment method for high-concentration DMF wastewater according to claim 1, is characterized in that, The enrichment culture medium with DMF as the sole carbon and nitrogen source at different concentrations as described in step S2 is respectively 0.5%, 1%, 1.5%, 2%, 2.5%, and 3% of the enrichment culture medium with DMF as the sole carbon and nitrogen source.

3. a biological treatment method for high-concentration DMF wastewater according to claim 1, is characterized in that, The culture conditions in step S2 are specifically: culture at 30° C. and pH 7.

4. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, The microorganisms of the mixed strains in step S5 include Paracoccus, Pseudomonas, Alcaligenes, Ochrobacturm, and Bacillus.

5. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, The carbon source in step S4 and the carbon source in step S9 include glucose and starch.

6. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, In the high-concentration DMF wastewater described in step S7, the ratio of biodegradable organic carbon to total organic carbon is greater than 50%, B / C>0.3, COD is 10,000-30,000 mg / L, and the DMF concentration is 500-3,500 mg / L.

7. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, In step S7, the fermentation system is fed with water intermittently at a low load in the early stage, and then fed with water continuously at a high load in the later stage.

8. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, Before adding the mixed bacterial strains in step S7, urea and phosphate are added to make the molar ratio of C:N:P in the wastewater equal to 190-210:4-6:

1.

9. a biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, The composition of the mixed microorganisms in step S8 is 25-36% Paracoccus genus, 23-30% Pseudomonas genus, 18-22% Alcaligenes genus, 15-20% Ochrobacturm genus, 10-15% Bacillus genus and others <5%.

10. A biological treatment method for high-concentration DMF wastewater according to claim 1, characterized in that, The growth factors described in step S9 are vitamins, biotin and trace elements.

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