DMSO-containing high-concentration wastewater functional microorganism gradient targeted treatment process

Abstract

The application relates to the field of wastewater treatment, in particular to a functional microorganism gradient targeted treatment process for high-concentration wastewater containing DMSO. In the application, the strain is subjected to adaptive screening first, then pretreated through a hydrolysis acidification tank, and then treated through an AO treatment unit, so that the treatment of high-concentration DMSO wastewater can be applicable, the cost can be effectively reduced, and the stability can be improved.

Description

Technical Field

[0001] This application relates to the field of wastewater treatment, and in particular to a functional microbial gradient targeted treatment process for wastewater containing high concentrations of DMSO. Background Technology

[0002] Dimethyl sulfoxide (DMSO) is a highly polar, high-boiling-point, and thermally stable aprotic organic solvent widely used in chemical synthesis, carbon fiber preparation, and pharmaceutical extraction. Wastewater from these industries typically exhibits high DMSO concentrations, high COD levels, and poor biodegradability. Furthermore, the wastewater often contains trace amounts of suspended oils, and its degradation process easily generates highly toxic sulfur-containing intermediates, making treatment extremely difficult.

[0003] Currently, the mainstream processes for treating high-DMSO and high-COD wastewater in the industry are divided into two main categories: advanced oxidation processes and physicochemical coupled biochemical processes. Advanced oxidation processes mainly include Fenton oxidation, ozone oxidation, and electrochemical oxidation. Traditional Fenton oxidation suffers from drawbacks such as high iron sludge production, low hydrogen peroxide utilization, and high reagent consumption. While improved heterogeneous Fenton and fluidized bed Fenton processes optimize sludge production and applicable pH ranges, they are prone to incomplete CS bond breaking during DMSO degradation, generating recalcitrant methanesulfonate intermediates. Ozone oxidation struggles to achieve complete DMSO mineralization. Although microbubble ozone and UV-coupled ozone technologies can convert DMSO into readily biodegradable intermediates such as dimethyl sulfone and methanesulfonic acid, improving wastewater biodegradability, they generally suffer from low ozone utilization and high treatment costs. Electrochemical oxidation requires no external reagents, relying on electrode reactions to generate highly oxidizing active groups to degrade organic matter, resulting in low secondary pollution risk. However, it is limited by water conductivity and suffers from low energy utilization, expensive electrodes, and high operating energy consumption. Physicochemical coupling biochemical process has low operation and maintenance costs and almost no secondary pollution, but DMSO itself is biotoxic. When the mass concentration is greater than 100 mg / L, DMSO can significantly inhibit the activity of microbial metabolic enzymes, especially by interfering with cell membrane permeability and hindering substrate transport. This can easily cause inactivation of microorganisms and paralysis or collapse of the biochemical system. Summary of the Invention

[0004] Based on the above problems, the purpose of this application is to develop a combined treatment process that is synergistic, thoroughly degrades, operates at low cost, and is suitable for highly toxic DMSO wastewater, in order to solve the problems of high biological toxicity of DMSO, poor biodegradability of wastewater, and difficulty in the survival of microorganisms in the biological system.

[0005] This application provides a functional microbial gradient targeted treatment process for high-concentration DMSO wastewater, comprising the following steps: S1. Take wastewater samples and screen the bacterial strains for DMSO tolerance to obtain the first, second, third, and fourth microorganisms; S2. Wastewater is pretreated in a regulating tank; S3. The effluent from the equalization tank passes through the hydrolysis acidification tank, where DMSO and macromolecular organic matter are decomposed into small molecule organic acids. The hydrolysis acidification tank contains a first microorganism. S4. The effluent from the hydrolysis acidification tank enters the anaerobic tank, where a second microorganism is added. S5. The effluent from the anaerobic tank is treated by at least one round of AO treatment unit. The AO treatment unit includes an anoxic tank and an aerobic tank arranged in sequence. A third microorganism is added to the anoxic tank and a fourth microorganism is added to the aerobic tank. S6. After the effluent from step S5, suspended sludge, colloids and microorganisms are intercepted in the MBR membrane tank; In the hydrolysis acidification tank, anaerobic tank, anoxic tank, and aerobic tank, the addition rates of the first, second, third, and fourth microorganisms were 1×10⁻⁶. 9 For suspensions measured in CFU / mL, the concentration should not exceed 2%; Discrete biological substrates are also added to the hydrolysis acidification tank, anaerobic tank, anoxic tank and aerobic tank; The water retention time in the hydrolysis acidification tank is 48–60 h, and the dissolved oxygen in the hydrolysis acidification tank is 0.1–0.5 mg / L.

[0006] In traditional methods, DMSO concentrations greater than 100 mg / L can significantly inhibit the activity of microbial metabolic enzymes, particularly by interfering with cell membrane permeability and hindering substrate transport, leading to strain inactivation and system collapse. This invention employs a gradient-targeted treatment strategy, using a multi-stage progression from hydrolysis and acidification to anaerobic digestion (AO) and microbial bioreactor (MBR), combined with dedicated DMSO-tolerant microorganisms in each unit. This significantly improves the tolerance to DMSO concentrations, achieving highly efficient biodegradation of extremely toxic wastewater.

[0007] In the above scheme, the microbial control adopts the method of first screening for DMSO tolerance and then administering the drug. The microorganisms are pre-screened by wastewater samples and then subjected to gradient degradation. On the one hand, this significantly reduces the amount of microorganisms to be administered, and the operation and maintenance costs are significantly reduced. On the other hand, the enhanced tolerance of the microorganisms after the pre-screening treatment also significantly increases the retention time of the microorganisms in the water, and significantly reduces the operation and maintenance costs of the system.

[0008] Based on the above, this scheme adopts a progressive treatment process with multi-stage coupled degradation of pollutants. It is particularly effective for high-concentration DMSO wastewater, where DMSO and some large protein molecules are decomposed into organic acids in the hydrolysis acidification tank. This increases the B / C ratio to over 0.3, facilitating further degradation of pollutants in the ordered anaerobic, anoxic, and aerobic tanks, thus creating conditions for subsequent treatment. Overall, by using the hydrolysis acidification tank in conjunction with adaptive screening of microbial strains, this approach is applicable to high-concentration DMSO wastewater, improving microbial activity and maintaining operational stability. Furthermore, it reduces the amount of microorganisms required and the frequency of replenishment, saving costs.

[0009] Additionally, it should be noted that the amount of microorganisms added in this plan refers to the relative mass of the pool volume.

[0010] Preferably, the specific method of step S1 is as follows: Take activated sludge or bacterial strains and inoculate them into a culture medium containing wastewater. Based on 100 parts by weight of wastewater, the culture medium contains the following components: 1-2 parts nitrogen source; Sugar 0.1 to 1 part; After screening to an OD600 of not less than 1.5, further culture was carried out.

[0011] The above scheme uses wastewater as a substrate, directly exposing the screening process to real water quality conditions. This helps improve the natural adaptability of the obtained strains and avoids the problem of a sudden drop in activity of strains screened in the laboratory under actual working conditions. Overall, it improves the activity of the strains and reduces the frequency of microbial replenishment. In the above culture medium system, after screening to an OD600 of not less than 1.5, further culture is carried out, which can quickly establish the dominant strain in the reactor and reduce the start-up period. At the same time, the sugar content in the above system is generally low. The main purpose is to prevent the strains from preferentially utilizing sugar components and reducing the decomposition of DMSO. Overall, it can provide a biodegradation environment with good strain activity, rapid start-up, and stable survival.

[0012] Preferably, the activated sludge or strains and screening conditions used for the first, second, third, and fourth microorganisms are as follows: First microorganism: Hydrolyzed acidified tank bottom sludge; Second microorganism: sludge from anaerobic reactors was selected; Third microorganism: Denitrifying bacteria are selected; Fourth microorganism: aerobic activated sludge is selected.

[0013] In the above scheme, the most suitable original bacterial source was selected based on the metabolic characteristics of different functional units, which significantly improved the enrichment efficiency of functional bacteria in each unit. The bottom sludge of the hydrolysis acidification tank usually contains hydrolytic acid-producing bacteria, which can convert DMSO and large molecular organic matter (such as protein, cellulose, etc.) into small molecular organic acids. The second and fourth microorganisms both used sludge as a base, mainly because the bottom sludge itself contains a variety of synergistic bacterial species. Through long-term use, it has developed a certain degree of adaptability, which can significantly shorten the expansion cycle during further screening and amplification. An acclimatization period of only 3-5 days is sufficient to achieve a bacterial concentration with an OD600 of not less than 1.5. Commercially available denitrifying bacteria were selected for the third microorganism because the denitrification function requirement in this step is clear and highly standardized. Directly using commercially available products avoids the time cost of self-screening, and the bacteria themselves have a certain tolerance to DMSO, eliminating the need for pre-screening of sludge while ensuring reliable and stable nitrogen removal performance.

[0014] Preferably, during the first microbial screening process, the pH value is first controlled at 5 to 6.5, and after culturing for 6 to 24 hours, the pH is adjusted to 7.0 to 8.0, and the dissolved oxygen in the environment is 0.1 to 0.5 mg / L.

[0015] In the initial stage of the system, microbial strains are screened using a weakly acidic environment to inhibit the excessive proliferation of acid-sensitive bacteria. Although the overall pH value in wastewater treatment can be adjusted to control the overall acidity and alkalinity of the acidification tank and improve the protection of microbial strains, the large volume of the tank often leads to localized slightly acidic environments during operation, which can cause strain inactivation. Therefore, the above scheme employs early acidic screening followed by restoration to neutral conditions to protect the activity of microbial strains. The resulting microbial community possesses both acid-producing and acid-resistant capabilities and can maintain high metabolic activity in a neutral environment. Simultaneously, microaerobic conditions with an oxygen content of 0.1–0.5 mg / L are used to further selectively screen for microbial communities with a dominant facultative anaerobic metabolic pathway. These microbial communities preferentially utilize fermentation for acid production metabolism under low-oxygen conditions rather than aerobic respiration, ensuring stable hydrolysis and acidification functions.

[0016] Preferably, during the first microbial screening process, cellulose or starch is also added to the culture medium, with the cellulose or starch content being 0.1 to 0.3 parts by weight.

[0017] Small amounts of cellulose or starch can introduce large organic molecules into the system, which cannot be directly absorbed and utilized by microorganisms. This allows for the screening of strains with extracellular enzymes, enabling them to gain a growth advantage and eliminating strains that can only utilize simple sugars. Therefore, it can simulate the environment containing large molecular residues in actual wastewater as much as possible, resulting in a broader substrate spectrum for the resulting microbial community and higher degradation efficiency in field applications.

[0018] Preferably, in step S5, the wastewater is treated sequentially through a primary AO microbial targeted treatment unit, a secondary sedimentation tank for sludge-water separation, and a secondary AO microbial targeted treatment unit. The primary AO microbial targeted treatment unit includes a primary anoxic tank and a primary aerobic tank, and the secondary AO microbial targeted treatment unit includes a secondary anoxic tank and a secondary aerobic tank.

[0019] In the above system, graded degradation by load avoids overload of a single-stage system due to high concentrations, thus improving overall degradation efficiency. The primary AO unit has a larger sludge discharge and shorter sludge age, which is conducive to the rapid proliferation of heterotrophic bacteria; the secondary AO unit has a longer sludge age, which is conducive to the enrichment of slow-growing bacteria such as nitrifying bacteria, improving denitrification efficiency. Differential regulation of sludge age between the two AO units is achieved through sludge-water separation and sludge discharge control in the secondary sedimentation tank. When influent water quality fluctuates, the primary AO unit can act as a buffer barrier to absorb shock loads, ensuring the stable operation of the secondary AO unit and preventing the inactivation of bacteria in the secondary AO unit. The clarified liquid is sent to the secondary AO system to avoid high concentrations impacting downstream processes. After passing through two AO stages and the secondary sedimentation tank, the colloidal concentration entering the MBR is significantly reduced, significantly minimizing membrane flux decline.

[0020] Preferably, with 1×10 9 For the CFU / mL suspension meter, the microbial addition amount in the primary AO microbial targeted treatment unit is 1.0–2.0%, and the microbial addition amount in the secondary AO microbial targeted treatment unit is 0.5–1.0%.

[0021] The primary AO influent still contains high concentrations of DMSO and residual COD, posing a dual challenge to microorganisms: toxicity inhibition and high operating load. A relatively high dosage of 1.0–2.0% ensures the system can quickly establish a dominant microbial species, while providing sufficient biomass to buffer against toxic shocks and shorten system start-up time. Lower dosages are used in the later stages to save costs and prevent excessive microbial growth that could lead to premature sludge age and loss of nitrifying bacteria.

[0022] Preferably, the water retention time of the primary AO microbial targeted treatment unit is 24-36 hours, and the water retention time of the secondary AO microbial targeted treatment unit is 12-18 hours. In the primary and secondary AO microbial targeted treatment units, the ratio of the water retention time of the anoxic tank to the aerobic tank is 1-3:1.

[0023] In the above scheme, the first-stage water retention time (HRT) is relatively long, providing sufficient time for the slow hydrolysis acidification products (such as long-chain fatty acids) to be fully degraded; the second-stage HRT is relatively short, because the remaining organic matter is mostly easily degradable small molecules, which do not need to be retained for too long. Overall, this improves efficiency while ensuring sufficient reaction time, guaranteeing sufficient nitration time, and reducing the consumption of external carbon sources.

[0024] Preferably, in steps S3 to S5, the pH value is controlled to be 7.0 to 8.0.

[0025] The pH range described above provides a stable pH interval for various bacterial species, eliminating the need for individual adjustment of each tank, thus simplifying the operation process and the amount of bacteria added. Furthermore, since the methanesulfonic acid, sulfate, and other acidic substances produced during the degradation process in the hydrolysis acidification tank can cause a decrease in the system's pH, controlling the pH range provides sufficient buffering capacity. A slightly alkaline environment is beneficial for guiding the degradation of DMSO towards the oxidation pathway, inhibiting the formation of dimethyl sulfide in the reduction pathway. Simultaneously, alkaline conditions facilitate the absorption of acidic gases such as hydrogen sulfide, reducing the emission of malodorous gases.

[0026] Preferably, in step S4, the water retention time in the anaerobic tank is 24–36 h.

[0027] This time frame ensures that acid-producing and methanogenic bacteria have sufficient time to further degrade organic acids into smaller molecules, achieving a COD removal rate of 45-55%, and further allows sulfides ample time to react with metal ions (Fe) in the sludge. 2+ (etc.) combine to form insoluble metal sulfide precipitates, which are fixed in the sludge, reducing the content of sulfides in the effluent and the release of malodorous gases.

[0028] In summary, this application, by first screening the bacterial strains for adaptability, then pretreating them in a hydrolysis acidification tank, and finally treating them in an AO treatment unit, can be applied to the treatment of high-concentration DMSO wastewater, effectively reducing costs and improving stability. Attached Figure Description

[0029] Figure 1 This is a flowchart of the wastewater treatment system in Embodiment 1 of this application. Detailed Implementation

[0030] The technical solutions in this application will be further described through the following specific embodiments.

[0031] In the following examples, the wastewater is sourced from a chemical wastewater source, with a DMSO concentration of 7600 mg / L and an influent COD of 26,000 mg / L.

[0032] In the following embodiments, the discrete biomaterial is a carbon-based biomaterial developed by Hunan Zhongfu Environmental Protection Technology Research Institute Co., Ltd., and the specific preparation method is as shown in Example 1 of patent application number CN121913595A.

[0033] Example 1, the overall flowchart is as follows Figure 1 As shown, this embodiment includes the following steps: S1. Screening of bacterial strains, as detailed below: First microbial screening: The bottom sludge of the hydrolysis acidification tank of the sewage treatment plant was used as the inoculum source, with an SVI value of 65 mL / g.

[0034] Prepare the culture medium according to the following mass proportions: 100 samples of raw wastewater; 1.0 part peptone; 0.3 parts beef extract; 0.5 parts glucose; 0.2 parts corn starch.

[0035] In the above system, the pH was controlled at 6.0 using phosphate buffer, the temperature at 30℃, the stirring rate at 50 rpm, and the dissolved oxygen at 0.3 mg / L. The system was incubated for 12 h, and then the pH was adjusted to 7.2 using sodium phosphate. The OD600 was measured every 6 h until it was not lower than 1.5, thus completing the screening.

[0036] The second microorganism was selected from the crushed UASB granular sludge in the anaerobic reactor as the inoculum source. The third microorganism was selected from commercially available denitrifying bacteria (including Paracoccus, Pseudomonas and other bacteria) as the inoculum source. The fourth microorganism was selected from the aerobic activated sludge in the aeration tank of a municipal wastewater treatment plant as the inoculum source.

[0037] The screening methods for the second, third, and fourth microorganisms are as follows: Prepare the culture medium according to the following mass proportions: 100 samples of raw wastewater; 1.0 part peptone; 0.3 parts beef extract; 0.5 parts glucose.

[0038] The pH of the above system was controlled at 7.2 using phosphate buffer solution. During the third microbial screening, an additional 0.3 parts of sodium nitrate were added to provide nitrate ions.

[0039] The screening conditions for the second microorganism are as follows: the dissolved oxygen content is reduced to less than 0.1 mg / L by blowing with a nitrogen / carbon dioxide mixed gas, stirred at 120 rpm at 35°C, and the OD600 is measured every 6 hours until it is not lower than 1.5, thus completing the screening.

[0040] The screening conditions for the third microorganism are as follows: control the dissolved oxygen at 0.2 mg / L, stir at 30℃ and 80 rpm, measure OD600 every 6 hours until it is not lower than 1.5, and the screening is completed.

[0041] The screening conditions for the fourth microorganism are as follows: the dissolved oxygen content is controlled at 3.0 mg / L, the mixture is stirred at 30℃ and 150 rpm, and the OD600 is measured every 6 hours until it is not lower than 1.5, thus completing the screening.

[0042] S2. Pre-treatment of raw wastewater is carried out as follows: Wastewater is filtered through a screen to remove suspended solids >5mm, and then enters an equalization tank. The pH in the equalization tank is adjusted to 7.5 with sodium hydroxide and hydrochloric acid, and then homogenized for 16 hours. The effluent then enters an acidification tank.

[0043] S3. Hydrolysis acidification tank treatment: Add 3wt‰ discrete carbon-based biological substrate and 2wt% primary microorganism to the hydrolysis acidification tank, HRT=48h, dissolved oxygen (DO)=0.3mg / L, water temperature controlled at 25~30℃, pH=7.5, sludge concentration (MLSS) controlled at 4000~5000mg / L.

[0044] S4. Anaerobic treatment: The effluent from the hydrolysis acidification tank enters the anaerobic UASB, and 3wt‰ discrete carbon-based biological substrate and 1.5wt% secondary microorganism are added. HRT=36h, water temperature is controlled at 30~35℃, pH=7.5, MLSS is controlled at 6000~8000mg / L, upflow velocity is controlled at 1.2m / h, and oxygen content is controlled below 0.1mg / L.

[0045] S5, AO System Treatment: The effluent from the anaerobic tank is treated sequentially by a primary AO microbial targeted treatment unit, a secondary sedimentation tank, and a secondary AO microbial targeted treatment unit. The primary AO microbial targeted treatment unit includes a first anoxic tank and a first aerobic tank. The first anoxic tank is treated with 2 wt‰ discrete carbon-based biological substrate and 1.5 wt% of a third microorganism, with an HRT of 24 h, an oxygen content of 0.3 mg / L, and a pH of 7.5. The effluent from the first anoxic tank enters the first aerobic tank, where 2 wt‰ discrete carbon-based biological substrate and 1.5 wt% of a fourth microorganism are added, with an HRT of 12 h, a pH controlled at 7.5, and an oxygen content controlled at 3.0 mg / L.

[0046] The effluent from the primary AO microbial targeted treatment unit enters the secondary sedimentation tank for sludge-water separation. The clarified wastewater then enters the secondary AO microbial targeted treatment unit. Returned sludge replenishes the microbial biomass in the hydrolysis and acidification tank, maintaining a stable sludge concentration in the system. Simultaneously, excess sludge is transported to the biological sludge treatment tank for disposal. The secondary AO microbial targeted treatment unit includes a second anoxic tank and a second aerobic tank. The second anoxic tank is treated with 1 wt‰ discrete carbon-based biological substrate and 0.5 wt% of a third microorganism, with a HRT of 12 h, oxygen content of 0.3 mg / L, and pH of 7.5. The effluent from the second anoxic tank enters the second aerobic tank, where 1 wt‰ discrete carbon-based biological substrate and 0.5 wt% of a fourth microorganism are added. The HRT is 6 h, pH is controlled at 7.5, and oxygen content is controlled at 3.0 mg / L.

[0047] S6. The effluent from the second aerobic tank enters the MBR membrane tank for filtration. The effluent from the MBR membrane tank is clear water and can be discharged directly. At the same time, part of the sludge produced by the MBR membrane tank is returned to the secondary anoxic tank to replenish the microbial concentration. The remaining sludge, together with the remaining sludge in the secondary sedimentation tank, enters the biological sludge tank and is then treated by plate and frame filter press.

[0048] Example 2 differs from Example 1 in that, in step S1, corn starch is not added to the culture medium during the first microbial screening process.

[0049] Example 3 differs from Example 1 in that the amount of microorganisms added in the first anoxic tank and the first aerobic tank is 2.0%, while the amount of microorganisms added in the second anoxic tank and the second aerobic tank is 1.0%.

[0050] Example 4 differs from Example 1 in that the HRT of the first anoxic tank is 18h, the HRT of the first aerobic tank is 18h, the HRT of the second anoxic tank is 9h, and the HRT of the second aerobic tank is 9h.

[0051] Example 5 differs from Example 1 in that the HRT of the first anoxic tank is 27h, the HRT of the first aerobic tank is 9h, the HRT of the second anoxic tank is 13.5h, and the HRT of the second aerobic tank is 4.5h.

[0052] Example 6 differs from Example 1 in that the HRT of the first anoxic tank is 12h, the HRT of the first aerobic tank is 24h, the HRT of the second anoxic tank is 6h, and the HRT of the second aerobic tank is 12h.

[0053] Example 7 differs from Example 1 in that, in step S1, the pH is always controlled at 7.2 while the total culture time remains unchanged during the cultivation of the first microorganism.

[0054] Additionally, the comparison examples are set as follows: Comparative Example 1 differs from Example 1 in that it does not include a hydrolysis acidification tank; the pretreated wastewater is directly fed into an anaerobic tank for further treatment. The remaining process parameters are the same as in Example 1.

[0055] Comparative Example 2 differs from Example 1 in that deionized water was used instead of wastewater during the cultivation of each bacterial strain. Simultaneously, peptone was added to the culture medium to achieve the same COD as the wastewater, based on the COD of the wastewater.

[0056] Comparative Example 3 uses a traditional biochemical route, specifically including pretreatment, ozone treatment, Fenton oxidation, coagulation, AO treatment, MBR membrane tank, and clear water tank. The details of each step are as follows: Ozone treatment: An air ozone generator is used with a gas concentration of 20 mg / L and an ozone concentration of 200 mg / L. A microbubble aeration contact tower is used with a gas-to-water ratio of 3:1, a temperature control range of 20-25℃, and a contact time of 60 min.

[0057] Fenton oxidation: After ozone treatment, the product enters the oxidation tank, where ferrous sulfate (800 mg / L based on ferrous ions) and 30% hydrogen peroxide (1200 mg / L) are added. At the same time, sulfuric acid is added to adjust the pH to 3.5, and the temperature is controlled within the range of 20-25℃. The reaction is carried out for 2 hours.

[0058] Coagulation: Add polyaluminum chloride at a concentration of 300 mg / L and polyacrylamide at a concentration of 5 mg / L. At the same time, adjust the pH value to the range of 8.0-8.5 with sodium hydroxide. React for 30 min, precipitate for 120 min, and then treat the supernatant effluent with AO.

[0059] The AO processing steps are performed using the AO processing method in step S5 of Example 1.

[0060] Table 1 shows the effluent detection and operating status of each step in Examples 1-6 and Comparative Examples 1-3.

[0061]

[0062] Overall, the solution in Example 1 has lower operating costs, simpler maintenance, and stable biofilm formation on the carbon-based substrate. The specialized microbial strains are highly resistant to toxicity, eliminating the need for frequent replenishment of microbial agents. The entire process is shock-resistant and fluctuation-resistant, requiring no expensive advanced oxidizing agents, with a treatment cost of only 38.6 yuan per ton of water. Compared to the 155 yuan / ton treatment cost in Comparative Example 3, this represents a reduction of over 75%, demonstrating significant economic and practical advantages for industrial application. In contrast to Comparative Example 1, the absence of an acidification pretreatment step resulted in a direct impact of large-molecule DMSO on the anaerobic system, leading to a sharp decline in treatment efficiency. Compared to Comparative Example 2, high concentrations of DMSO are highly toxic to unselected microorganisms. On one hand, the strains have poor bioavailability, requiring frequent replenishment, significantly increasing usage and maintenance costs. On the other hand, high concentrations of unselected microorganisms have a poor decomposition effect on DMSO.

[0063] In Example 2, no starch was added during the cultivation process, resulting in slightly lower stability of the bacterial strain during acidification compared to the strain in the hydrolysis acidification tank. This decreased stability also led to a higher frequency of strain replenishment. In Example 7, neutral conditions were used directly during the bacterial cultivation process, resulting in poor strain stability in the hydrolysis acidification tank, and a slight increase in the final DMSO content. In Examples 4-6, the water retention times in the anoxic and aerobic tanks were adjusted. It was observed that if the water retention time in the aerobic tank was too long, or the water retention time in the anoxic tank was too short, the final filtered water would still contain a high COD, resulting in a slight decrease in purification efficiency.

[0064] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A functional microbial gradient targeted treatment process for high-concentration DMSO wastewater, characterized in that, The steps include the following: S1. Take wastewater samples and screen the bacterial strains for DMSO tolerance to obtain the first, second, third, and fourth microorganisms. The specific method of step S1 is as follows: Take activated sludge or bacterial strains and inoculate them into a culture medium containing wastewater. The culture medium contains the following components per 100 parts by weight of wastewater: 1-2 parts nitrogen source; Sugar 0.1 to 1 part; After screening to a level with an OD600 of not less than 1.5, further expansion culture is carried out. The activated sludge or bacterial strains used for the first, second, third, and fourth microorganisms are as follows: the first microorganism is selected from the bottom sludge of the hydrolysis acidification tank; the second microorganism is selected from the sludge of the anaerobic reaction tank; the third microorganism is selected from denitrifying bacteria; and the fourth microorganism is selected from aerobic activated sludge. During the screening of the first microorganism, the pH value was first controlled at 5-6.5, and after culturing for 6-24 hours, the pH was adjusted to 7.0-8.0, and the dissolved oxygen in the environment was 0.1-0.5 mg / L. S2. Wastewater is pretreated in a regulating tank; S3. The effluent from the equalization tank passes through the hydrolysis acidification tank, where DMSO and macromolecular organic matter are decomposed into small molecule organic acids. The hydrolysis acidification tank contains a first microorganism. S4. The effluent from the hydrolysis acidification tank enters the anaerobic tank, where a second microorganism is added. S5. The effluent from the anaerobic tank is treated by at least one round of AO treatment unit. The AO treatment unit includes an anoxic tank and an aerobic tank arranged in sequence. A third microorganism is added to the anoxic tank and a fourth microorganism is added to the aerobic tank. S6. After the effluent from step S5, suspended sludge, colloids and microorganisms are intercepted in the MBR membrane tank; In the hydrolysis acidification tank, anaerobic tank, anoxic tank, and aerobic tank, the addition rates of the first, second, third, and fourth microorganisms were 1×10⁻⁶. 9 For suspensions measured in CFU / mL, the concentration should not exceed 2%; Discrete biological substrates are also added to the hydrolysis acidification tank, anaerobic tank, anoxic tank and aerobic tank; The water retention time in the hydrolysis acidification tank is 48–60 h, and the dissolved oxygen in the hydrolysis acidification tank is 0.1–0.5 mg / L.

2. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 1, characterized in that, During the first microbial screening process, cellulose or starch was also added to the culture medium, with a mass fraction of 0.1 to 0.3 parts of cellulose or starch.

3. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 1, characterized in that, In step S5, the wastewater is treated sequentially through a primary AO microbial targeted treatment unit, a secondary sedimentation tank for sludge-water separation, and a secondary AO microbial targeted treatment unit. The primary AO microbial targeted treatment unit includes a primary anoxic tank and a primary aerobic tank, and the secondary AO microbial targeted treatment unit includes a secondary anoxic tank and a secondary aerobic tank.

4. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 3, characterized in that, With 1×10 9 For the CFU / mL suspension meter, the microbial addition amount in the primary AO microbial targeted treatment unit is 1.0–2.0%, and the microbial addition amount in the secondary AO microbial targeted treatment unit is 0.5–1.0%.

5. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 3, characterized in that, The water retention time in the primary AO microbial targeted treatment unit is 24–36 h, and the water retention time in the secondary AO microbial targeted treatment unit is 12–18 h. In the primary and secondary AO microbial targeted treatment units, the ratio of water retention time in the anoxic tank to that in the aerobic tank is 1–3:

1.

6. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 1, characterized in that, In steps S3 to S5, the pH value is controlled to be 7.0 to 8.

0.

7. The functional microbial gradient targeted treatment process for high-concentration DMSO wastewater according to claim 1, characterized in that, In step S4, the water retention time in the anaerobic tank is 24–36 hours.

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