Device and method for reducing biotoxicity of organic matters in tail water of sewage plant

Abstract

The invention discloses a device and a method for reducing biotoxicity of organic matters in tail water of a sewage plant, and belongs to the technical field of sewage treatment. In practical application, aerobic starved sludge with different aeration durations is selected and compounded and mixed according to a specific proportion, and the optimal functional proportion is found. The method has the core advantages that the activated sludge is treated by means of continuous aeration, the functional structure of sludge particles is changed, and the biotoxicity of organic matters in tail water of a sewage plant is reduced. Meanwhile, functional bacteria generated in the aerobic starvation treatment process are utilized, so that the biotoxicity of the tail water is further reduced. The method not only can greatly reduce resource consumption and disposal cost in the tail water treatment process, but also opens up a new path for recycling of water resources, and assists the sewage treatment field to realize green and efficient development.

Description

Technical Field

[0001] The present invention belongs to the technical field of sewage treatment, and particularly relates to a device and method for reducing the biological toxicity of organic matter in the effluent of a sewage treatment plant. Background Art

[0002] With the rapid development of industrialization and urbanization, the problems of water resource shortage and pollution have become more serious. Sewage treatment plants play a key role as a bridge in sewage treatment and reclaimed water utilization. However, due to the limited processes of most sewage treatment plants in China, the pollutant removal effect is limited. As a result, the organic pollutants that have not been completely removed are discharged into environmental water bodies with the effluent, causing hazards such as water eutrophication, fishery breeding pollution, and reduction of biodiversity. Traditional sewage effluent treatment methods often have difficulty effectively reducing the biological toxicity of refractory organic pollutants. Although the effluent of the sewage treatment plant meets the corresponding water quality standards after treatment, some trace pollutants that have not been completely removed still pose great ecological risks and health hazards. Therefore, the effluent of the sewage treatment plant needs to be deeply treated to reduce the impact of its biological toxicity.

[0003] Currently, the commonly used sewage treatment methods for sewage treatment plant effluent mainly include physical and chemical methods, biological methods, and combined treatment processes that combine multiple methods. Specifically, they mainly include membrane separation, adsorption, coagulation, photochemical oxidation, electrochemical oxidation, biofilm, constructed wetland, etc. Among them, the aerobic starvation sludge method has an efficient effect on the removal of organic matter in the effluent. By continuously aerating the activated sludge, the microorganisms in the sludge can utilize the aerobic endogenous respiration process to oxidize the cell protoplasm, and the substances released by cell decay can efficiently remove pollutants. Research shows that the degradation rate of bisphenol A (BPA) in the effluent of the sewage treatment plant treated by the aerobic starvation sludge method reaches the maximum value of 0.8 mg / g VSS·h on the 43rd day, and the degradation rates of bisphenol AF (BPAF) (11.4 mg / g VSS·h) and gabapentin (GBP) (8.9 mg / g VSS·h) are the highest.

[0004] Although the aerobic starvation sludge method can remove certain organic matters in the effluent of the sewage treatment plant to a certain extent and achieve efficient purification of the sewage effluent, there are numerous organic pollutants in the effluent of the sewage treatment plant. It is extremely laborious to test the pollutant removal effect using physical and chemical detection methods, and whether multiple mixed pollutants have joint toxicity and whether more toxic degradation products are generated during pollutant removal are still unknown. Therefore, developing a scientific evaluation method to intuitively, systematically, and comprehensively evaluate the biological toxicity of organic matter in the effluent of the sewage treatment plant and the effect of the removal process will have great social and economic benefits and broad application prospects. Summary of the Invention

[0005] At present, the processes of most sewage treatment plants in China are limited, and the pollutant removal effect is limited, resulting in the centralized discharge of organic pollutants that have not been completely removed with the tail water. The existing sewage tail water treatment methods are difficult to effectively reduce the biological toxicity of refractory organic matter in the tail water. In view of the above problems, the present invention provides a device and method for reducing the biological toxicity of organic matter in the tail water of sewage treatment plants to improve the treatment efficiency of sewage and reduce its biological toxicity. The method of the present invention uses the sludge after aerobic starvation to mix and treat the sewage tail water, changes the sludge structure through the aerobic starvation process, and the functional bacteria in the starved sludge react with the tail water organic matter to achieve the effect of reducing the biological toxicity of the sewage tail water.

[0006] To solve the above problems, the present invention provides the following technical solutions:

[0007] The present invention provides a device for reducing the biological toxicity of organic matter in the tail water of a sewage treatment plant. The device includes an aeration tank, a reaction tank, a sedimentation tank, a reservoir, and a collection tank connected in sequence; the aeration tank is used to maintain the activated sludge in an aerobic starvation state under continuous aeration conditions, generate aerobic starved sludge, and transport it to the reaction tank; the reaction tank is used to mix and aerate the aerobic starved sludge and the tail water of the sewage treatment plant to generate mixed sewage and transport it to the sedimentation tank; the sedimentation tank is used to sediment the mixed sewage, part of the generated sludge is refluxed to the reaction tank, part is discharged, and the supernatant of the generated tail water is transported to the reservoir; the reservoir is used to store the supernatant of the tail water, and the obtained tail water is filtered through a water system filter membrane and then transported to the collection tank; an organic matter extraction device is arranged in the collection tank, the bottom of the organic matter extraction device is connected with an organic matter discharge pipe, and the upper part is connected with a drain pipe; the organic matter extraction device is used for enriching the organic pollutants in the tail water, and the enriched tail water organic matter is dissolved by a solvent and flows out through the organic matter discharge pipe for toxicity detection, and the enriched tail water is discharged to the natural water body through the drain pipe; wherein, the organic matter extraction device includes a solid phase extraction column and a collection pipe arranged in sequence from top to bottom, the solid phase extraction column is further connected with a volumetric flask and a nitrogen delivery pipe, the volumetric flask is provided with an organic phase and ultrapure water, and the collection pipe is further connected with a solvent delivery pipe.

[0008] Further, a sludge inlet pipe and a sludge discharge pipe are arranged on the aeration tank, the sludge inlet pipe is used to transport the activated sludge into the aeration tank; the aeration tank is used to maintain the activated sludge in an aerobic starvation state under continuous aeration conditions, thereby generating aerobic starved sludge; the sludge discharge pipe is used to transport the aerobic starved sludge into the reaction tank;

[0009] A water inlet pipe and a water outlet pipe are arranged on the reaction tank, the water inlet pipe is used to transport the tail water of the sewage treatment plant into the reaction tank; the reaction tank is used to mix and aerate the aerobic starved sludge and the tail water of the sewage treatment plant; the water outlet pipe is used to transport the mixed sewage generated by the reaction tank to the sedimentation tank;

[0010] A sludge return pipe, an excess sludge pipe and a water collecting pipe are provided on the sedimentation tank. The sedimentation tank is used to precipitate the mixed sewage to generate sludge and supernatant of the tail water; the sludge return pipe is used to return a part of the sludge to the reaction tank; the excess sludge pipe is used to discharge another part of the sludge; the water collecting pipe is used to transport the supernatant of the tail water to the reservoir;

[0011] The reservoir is used to convert the supernatant of the tail water into tail water, and the tail water is filtered by a water system filter membrane through a water delivery pipe and then transported to the collection tank.

[0012] The present invention also provides a method for reducing the biological toxicity of the tail water of a sewage treatment plant, characterized in that the method is applied to the device for reducing the biological toxicity of the tail water of a sewage treatment plant as claimed in claim 1 or claim 2; the method includes:

[0013] S1. The aeration tank maintains the activated sludge in an aerobic starvation state under continuous aeration conditions, generates aerobic starvation sludge and transports it to the reaction tank;

[0014] S2. The reaction tank mixes and aerates the aerobic starvation sludge with the tail water of the sewage treatment plant to generate mixed sewage and transports it to the sedimentation tank;

[0015] S3. The sedimentation tank precipitates the mixed sewage, a part of the generated sludge is returned to the reaction tank, another part is discharged, and the generated supernatant of the tail water is transported to the reservoir;

[0016] S4. The reservoir stores the supernatant of the tail water, and the obtained tail water is filtered by a water system filter membrane and then transported to the collection tank; the organic matter extraction device in the collection tank enriches the organic pollutants in the tail water, and the enriched organic matter in the tail water is dissolved by a solvent and then flows out through the organic matter discharge pipe for toxicity detection, and the enriched tail water is discharged to the natural water body through the drain pipe.

[0017] Further, in step S1, the concentration of the activated sludge entering the aeration tank is in the range of 5000 - 8000 mg / L, the aeration time of the activated sludge is 2 - 10 d, and the dissolved oxygen is greater than 2 mg / L.

[0018] Further, in step S2, the concentration of the aerobic starvation sludge is in the range of 2000 - 3000 mg / L, and the treatment time is 2 - 16 h.

[0019] Further, in step S3, the hydraulic retention time in the sedimentation tank is 20 - 24 h.

[0020] Further, in step S4, the pore size of the water system filter membrane is 0.45 μm.

[0021] Furthermore, step S4 specifically includes: after the volumetric flask sequentially activates the organic phase and cleans the solid phase extraction column with ultrapure water, the solid phase extraction column enriches the tail water, and after the enrichment is completed, the tail water organic matter is flushed into the collection tube with the organic phase and then concentrated by nitrogen blowing through the nitrogen delivery tube, and then the solvent delivery tube delivers the solvent to dissolve the organic matter to obtain a tail water organic matter sample.

[0022] Furthermore, the solvent contained in the volumetric flask is anhydrous methanol and ultrapure water, the injection volume is 10mL, and the flow rate is 10mL / min; the specification of the solid phase extraction column is HLB (hydrophilic-hydrophobic balance) 500mg / 6mL, and the tail water flow rate is 10mL / min; the nitrogen flow rate in the nitrogen delivery tube is controlled to be 15-20L / min, and the nitrogen delivery time is 1.5-2h until dry; the solvent contained in the solvent delivery tube is 0.4% DMSO (dimethyl sulfoxide), and the delivery volume is 1 / 1000 of the tail water injection volume.

[0023] Furthermore, the organism for toxicity testing is a zebrafish embryo at the 128-cell stage; the experimental indicators of the toxicity testing include the survival of zebrafish embryos, the hatching of zebrafish embryos, the number of tail swings of 28hpf (28h after fertilization) zebrafish embryos in 1 minute, the heart rate of 72hpf zebrafish embryos in 1 minute, and the body length of 72hpf zebrafish.

[0024] In a second aspect, the present invention provides a zebrafish toxicity testing method.

[0025] The method comprises: selecting normal adult zebrafish on the night before the experiment, placing them in a mating tank at a female-to-male ratio of 1:2, separating them with a partition, and keeping them away from light overnight. Light stimulation is applied at around 9:00 in the morning of the experiment, and the female and male fish mate and lay eggs after the partition is removed. The spawning ends about 30 minutes later, and the zebrafish embryos sink to the bottom of the mating tank. The zebrafish embryos are collected, dead embryos and unfertilized embryos are removed, and well-developed 128-cell stage embryos are selected for the experiment;

[0026] The exposure experiment was conducted on zebrafish embryos using a 6-well cell culture plate, with 20 zebrafish embryos 6 hours after fertilization (6 hpf) added to each well;

[0027] The experimental groups were set as plate control group (aquaculture system water), negative control group (aquaculture system water containing 0.4% DMSO), and sample group (tail water organic matter containing 0.4% DMSO);

[0028] The working solution volume of each well of the six-well cell plate is 10mL. Three parallel experiments are set up for each experimental group. The same concentration is replaced with fresh solution every 24 hours to ensure that the concentration of the exposure test solution remains unchanged. The exposure is continuous for 72 hours, and the treatment groups are observed and counted every day, and dead embryos are removed in time;

[0029] During the experiment, the survival of zebrafish embryos at 24 hpf, 48 hpf, and 72 hpf was counted; the hatching of zebrafish embryos at 48 hpf and 72 hpf was observed; a stereomicroscope was used to record the spontaneous movement video of zebrafish embryos at 28 hpf for 1 minute, and the number of tail beats was counted; at 72 hpf, zebrafish larvae were anesthetized with tricaine and fixed with 3.5% methylcellulose, the heart rate within 1 minute was counted, and after taking the phenotype map, the body length of zebrafish was measured using Image J software.

[0030] Advantages of the present invention:

[0031] (1) Traditional methods generally only remove the parent substances of organic matter in the tail water. The intermediate products have complex compositions, and comprehensive indicators such as the biological toxicity of the tail water organic matter cannot be fully evaluated. In the present invention, after experiencing the starvation stage, the microorganisms in the aerobic starved sludge have a higher affinity and uptake ability for pollutants in the environment, can quickly adsorb and degrade the toxic and harmful substances in the tail water, thereby efficiently reducing the biological toxicity of the tail water and providing a new method for tail water toxicity assessment. In practical applications, aerobic starved sludge with different aeration durations is selected and mixed in a specific ratio to explore the optimal functional ratio. The core advantage of the method of the present invention lies in changing the functional structure of sludge particles by continuous aeration treatment of activated sludge, reducing the biological toxicity of organic matter in the tail water of sewage treatment plants. At the same time, the functional bacteria generated during the aerobic starvation treatment are used to further reduce the biological toxicity of the tail water. This method can not only significantly reduce the resource consumption and disposal costs during the tail water treatment process, but also open up a new path for the recycling of water resources, helping the sewage treatment field to achieve green and efficient development.

[0032] (2) The device and method for reducing the biological toxicity of organic matter in the tail water of sewage treatment plants provided by the present invention are environmentally friendly. Using the natural metabolic process of microorganisms to reduce toxicity will not cause secondary pollution to the environment, meeting the requirements of sustainable development. At the same time, in the aerobic starved state, microorganisms will consume the stored substances in their bodies through their own metabolic regulation, reducing the sludge production, which helps to relieve the pressure of sludge disposal in sewage treatment plants. Description of the Drawings

[0033] Figure 1 It is a schematic structural diagram of a device for reducing the biological toxicity of organic matter in the tail water of sewage treatment plants provided by an embodiment of the present invention;

[0034] Figure 2 It is an enlarged structural diagram of the organic matter extraction device in an embodiment of the present invention;

[0035] Figure 3 It is the heavy metal ion content in the tail water after treatment with aerobic starved sludge at different times in Example 1;

[0036] Figure 4Length change of zebrafish at 72 hpf after treatment with aerobic starved sludge in Example 1;

[0037] Figure 5 Heart rate change of zebrafish embryos at 72 hpf after treatment with aerobic starved sludge in Example 2.

[0038] In the figure: 1 - Aeration tank, 2 - Reaction tank, 3 - Sedimentation tank, 4 - Reservoir, 5 - Collection tank, 6 - Inlet sludge pipe, 7 - Sludge discharge pipe, 8 - Inlet water pipe, 9 - Sludge return pipe, 10 - Excess sludge pipe, 11 - Outlet water pipe, 12 - Collector pipe, 13 - Water delivery pipe, 14 - Water system filter membrane, 15 - Organic matter extraction device, 16 - Volumetric flask, 17 - Solid phase extraction cartridge, 18 - Collection pipe, 19 - Nitrogen delivery pipe, 20 - Solvent delivery pipe, 21 - Organic matter discharge pipe, 22 - Drain pipe. Detailed implementation manners

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the present invention claimed, but merely represents selected embodiments of the present invention.

[0040] The present invention provides a device for reducing the biological toxicity of organic matter in the effluent of a sewage treatment plant, as Figure 1 shown. The device includes an aeration tank 1, a reaction tank 2, a sedimentation tank 3, a reservoir 4 and a collection tank 5 connected in sequence.

[0041] The aeration tank 1 is used to maintain the activated sludge in an aerobic starved state under continuous aeration conditions, generate aerobic starved sludge and transport it to the reaction tank 2; the reaction tank 2 is used to mix and aerate the aerobic starved sludge with the effluent of the sewage treatment plant to generate mixed sewage and transport it to the sedimentation tank 3; the sedimentation tank 3 is used to precipitate the mixed sewage, and part of the generated sludge is refluxed to the reaction tank 2 and the other part is discharged, and the supernatant of the generated tail water is transported to the reservoir 4; the reservoir 4 is used to store the supernatant of the tail water, and the obtained tail water is filtered through the water system filter membrane 14 and then transported to the collection tank 5; an organic matter extraction device 15 is arranged in the collection tank 5, the bottom of the organic matter extraction device 15 is connected with an organic matter discharge pipe 21, and the upper part is connected with a drain pipe 22; the organic matter extraction device 15 is used for enriching the organic pollutants in the tail water, and the enriched tail water organic matter is dissolved by a solvent and flows out through the organic matter discharge pipe 21 for toxicity detection, and the enriched tail water is discharged to the natural water body through the drain pipe 22.

[0042] Among them, as Figure 2 shown, the organic matter extraction device 15 includes a solid-phase extraction column 17 and a collection tube 18 arranged in sequence from top to bottom. The solid-phase extraction column 17 is also connected to a volumetric flask 16 and a nitrogen delivery pipe 19. An organic phase and ultrapure water are provided in the volumetric flask 16, and the collection tube 18 is also connected to a solvent delivery pipe 20.

[0043] Furthermore, a sludge inlet pipe 6 and a sludge discharge pipe 7 are provided on the aeration tank 1. The sludge inlet pipe 6 is used to transport activated sludge into the aeration tank 1; the aeration tank 1 is used to maintain the activated sludge in an aerobic starvation state under continuous aeration conditions, thereby generating aerobic starvation sludge; the sludge discharge pipe 7 is used to transport the aerobic starvation sludge into the reaction tank 2;

[0044] A water inlet pipe 8 and a water outlet pipe 11 are provided on the reaction tank 2. The water inlet pipe 8 is used to transport the effluent from the sewage treatment plant into the reaction tank 2; the reaction tank 2 is used to perform mixed aeration treatment on the aerobic starvation sludge and the effluent from the sewage treatment plant; the water outlet pipe 11 is used to transport the mixed sewage generated by the reaction tank 2 to the sedimentation tank 3;

[0045] A sludge return pipe 9, a surplus sludge pipe 10, and a water collection pipe 12 are provided on the sedimentation tank 3. The sedimentation tank 3 is used to precipitate the mixed sewage to generate sludge and supernatant of the tail water; the sludge return pipe 9 is used to return a part of the sludge to the reaction tank 2; the surplus sludge pipe 10 is used to discharge another part of the sludge; the water collection pipe 12 is used to transport the supernatant of the tail water to the reservoir 4;

[0046] The reservoir 4 is used to convert the supernatant of the tail water into tail water, and it is transported to the collection tank 5 after being filtered by the water system filter membrane 14 through the water delivery pipe 13.

[0047] Example 1:

[0048] In this example, the activated sludge from a certain sewage treatment plant in Changzhou was used as the inoculated sludge in the aeration tank. The sludge concentration was about 8500 mg / L, and continuous aeration treatment was carried out. The dissolved oxygen concentration was maintained above 1.5 mg / L. During the aeration process, sludge at different time points (0 d, 2 d, 5 d, 10 d, and the above mixed sludge) was selected for the experiment on reducing the toxicity of the tail water. The characteristics of the tail water were that the Cu 2+ content was 98 mg / L, and the Zn + content was 435 mg / L. The sludge concentration in the reaction tank was maintained at 3000 mg / L to allow the tail water to fully mix and contact with the aerobic starvation sludge. The conditions such as the mixing ratio, reaction time, and temperature were controlled. The reaction time was set to 2 h, 4 h, 8 h, 16 h, and the temperature was maintained in the range suitable for the growth of microorganisms, 25°C - 35°C. After the reaction, the water sample was detected, and the heavy metal ions Zn + , Cu 2+The content of [substance] was determined, and the toxicity reduction effect of the tail water organic matter was evaluated by means of biotoxicity testing methods.

[0049] The experimental results are as Figure 3 (a) shown. The heavy metal ions Cu 2+ and Zn + in the tail water of the sewage treatment plant had relatively high contents. After treatment with aerobic starved sludge for different times, the contents of both heavy metal ions decreased. Among them, Figure 3 (b) When treated with mixed starved sludge for 16 h, the content of Cu 2+ decreased to 31 μg / L. Figure 3 (c) When treated with mixed starved sludge for 16 h, the content of Zn + decreased to 87 μg / L. The aerobic starved sludge technology has a good effect on reducing organic matter. Figure 4 Figure [X] shows the body length change of zebrafish embryos at 72 hpf. After treatment with aerobic starved sludge, the body length of zebrafish increased significantly, and the effect was the best at 10 d and with mixed sludge.

[0050] Example 2:

[0051] In this example, the sewage source was the secondary biological treatment tail water (treated by the A2 / O process) of a municipal sewage treatment plant in Changzhou. The activated sludge collected from this sewage treatment plant was used as the inoculated sludge in the aeration tank, with a sludge concentration of about 7000 mg / L. Continuous aeration treatment was carried out, and the dissolved oxygen concentration was maintained above 2 mg / L. During the aeration process, sludge at different time points (0 d, 2 d, 5 d, 10 d, and the above mixed sludge) was selected for the tail water toxicity reduction experiment. A sequencing batch reactor (SBR) with an effective volume of 10 L was used. The dosing ratio was that the amount of aerobic starved sludge added was 20% of the tail water volume (i.e., 2 L of sludge + 8 L of tail water), ensuring a starved sludge concentration of 6000 mg / L. The reaction temperature was 20 - 25 °C, the pH was maintained at 7.0 - 7.5, and the reaction time was 8 hours. After the reaction ended, it was left to stand for 24 h, and the supernatant was taken and concentrated for zebrafish embryo toxicity detection.

[0052] The experimental results are as Figure 5 Figure [X] shows the heart rate change of zebrafish embryos at 72 hpf. After treatment with aerobic starved sludge, the heart rate of zebrafish increased significantly, and the heart rate was the highest when treated with mixed sludge for 8 h. The microorganisms in the starved sludge secreted more extracellular polymeric substances (EPS) due to the long-term lack of substrates, enhancing the adsorption ability to toxic substances. Although the metabolic activity of microorganisms decreased under the starved state, the expression of stress response genes (such as heavy metal resistance genes) was up-regulated, enhancing the detoxification ability.

[0053] The foregoing are only preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can still adjust the technical solutions described in the foregoing embodiments or make equivalent replacements for some of the technical features. Therefore, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, the present invention is also intended to include these changes and variations.

Claims

1. A device for reducing the biological toxicity of organic matter in tail water of a sewage plant, characterized in that: The device comprises an aeration tank (1), a reaction tank (2), a sedimentation tank (3), a water storage tank (4) and a collection tank (5) which are connected in sequence; The aeration tank (1) is used to maintain the activated sludge in an aerobic starved state under continuous aeration conditions, generate aerobic starved sludge and transport it to the reaction tank (2); The reaction tank (2) is used to mix and aerate the aerobic hungry sludge with the tail water of the sewage treatment plant to generate mixed sewage and transport it to the sedimentation tank (3); The sedimentation tank (3) is used to precipitate the mixed sewage, a part of the generated sludge is returned to the reaction tank (2), the other part is discharged, and the generated tail water supernatant is transported to the water storage tank (4); The water storage tank (4) is used to store the tail water supernatant, and the obtained tail water is filtered through the water filter membrane (14) and then transported to the collection tank (5); An organic matter extraction device (15) is arranged in the collection pool (5), and the bottom of the organic matter extraction device (15) is connected to an organic matter discharge pipe (21), and the top is connected to a drainage pipe (22); the organic matter extraction device (15) is used to enrich organic pollutants in tail water, and the enriched tail water organic matter is dissolved by a solvent and then flows out through the organic matter discharge pipe (21) for toxicity detection, and the enriched tail water is discharged to a natural water body through the drainage pipe (22); The organic matter extraction device (15) comprises a solid phase extraction column (17) and a collecting tube (18) arranged in sequence from top to bottom, the solid phase extraction column (17) is also connected to a volumetric flask (16) and a nitrogen delivery tube (19), an organic phase and ultrapure water are arranged in the volumetric flask (16), and the collecting tube (18) is also connected to a solvent delivery tube (20).

2. The device for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 1, characterized in that: The aeration tank (1) is provided with a sludge inlet pipe (6) and a sludge discharge pipe (7); the sludge inlet pipe (6) is used to transport the activated sludge into the aeration tank (1); the aeration tank (1) is used to maintain the activated sludge in an aerobic starved state under continuous aeration conditions, thereby generating aerobic starved sludge; the sludge discharge pipe (7) is used to transport the aerobic starved sludge into the reaction tank (2); The reaction tank (2) is provided with an inlet pipe (8) and an outlet pipe (11), wherein the inlet pipe (8) is used to transport tail water from the sewage treatment plant to the reaction tank (2); the reaction tank (2) is used to perform mixed aeration treatment on the aerobic hungry sludge and the tail water from the sewage treatment plant; the outlet pipe (11) is used to transport the mixed sewage generated by the reaction tank (2) to the sedimentation tank (3); The sedimentation tank (3) is provided with a sludge return pipe (9), a residual sludge pipe (10) and a water collecting pipe (12); the sedimentation tank (3) is used to precipitate the mixed sewage to generate sludge and tail water supernatant; the sludge return pipe (9) is used to return a part of the sludge to the reaction tank (2); the residual sludge pipe (10) is used to discharge another part of the sludge; the water collecting pipe (12) is used to transport the tail water supernatant to the water storage tank (4); The water storage tank (4) is used to convert the tail water supernatant into tail water, and the tail water is filtered through a water filter membrane (14) through a water pipe (13) and then transported to the collection tank (5).

3. A method for reducing the biological toxicity of organic matter in tail water of a sewage plant, characterized in that: The method is applied to the device for reducing the biological toxicity of organic matter in tail water of a sewage plant as claimed in claim 1 or claim 2; the method comprises: S1, aeration tank (1) maintains the activated sludge in an aerobic starved state under continuous aeration conditions, generates aerobic starved sludge and transports it to reaction tank (2); S2, reaction tank (2) mixes the aerobic hungry sludge with the tail water of the sewage treatment plant for aeration treatment to generate mixed sewage and transport it to the sedimentation tank (3); S3, the mixed sewage is precipitated in the sedimentation tank (3), a part of the generated sludge is returned to the reaction tank (2), the other part is discharged, and the generated tail water supernatant is transported to the water storage tank (4); S4, the water reservoir (4) accumulates the tail water supernatant, and the obtained tail water is filtered through a water filter membrane (14) and then transported to a collection tank (5); the organic matter extraction device (15) in the collection tank (5) enriches the organic pollutants in the tail water, and the enriched tail water organic matter is dissolved by a solvent and then discharged through an organic matter discharge pipe (21) for toxicity detection, and the enriched tail water is discharged to a natural water body through a drainage pipe (22).

4. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: In step S1, the concentration of activated sludge entering the aeration tank (1) is in the range of 5000-8000 mg / L, the activated sludge aeration time is 2-10 days, and the dissolved oxygen is greater than 2 mg / L.

5. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: In step S2, the concentration of aerobic starved sludge is in the range of 2000-3000 mg / L, and the treatment time is in the range of 2-16 h.

6. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: In step S3, the hydraulic retention time in the sedimentation tank (3) is 20-24 hours.

7. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: In step S4, the pore size of the water filter membrane (14) is 0.45 μm.

8. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: Step S4 specifically includes: the volumetric flask (16) sequentially activates the organic phase and cleans the solid phase extraction column (17) with ultrapure water, and then the solid phase extraction column (17) enriches the tail water, and after the enrichment is completed, the organic matter in the tail water is flushed to the collection tube (18) with the organic phase and then concentrated by nitrogen blowing through the nitrogen delivery tube (19), and then the solvent delivery tube (20) delivers the solvent to dissolve the organic matter, thereby obtaining a tail water organic matter sample.

9. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 8, characterized in that: The solvent contained in the volumetric flask (16) is anhydrous methanol and ultrapure water, the injection volume is 10 mL, and the flow rate is 10 mL / min; the specification of the solid phase extraction column (17) is HLB 500 mg / 6 mL, and the tail water flow rate is 10 mL / min; the nitrogen flow rate in the nitrogen delivery tube (19) is controlled to be 15-20 L / min, and the nitrogen delivery time is 1.5-2 h until it is blown dry; the solvent contained in the solvent delivery tube (20) is 0.4% DMSO, and the delivery volume is 1 / 1000 of the tail water injection volume.

10. The method for reducing the biological toxicity of organic matter in tail water of a sewage treatment plant according to claim 3, characterized in that: The organisms for the toxicity test are zebrafish embryos at the 128-cell stage; the experimental indicators for the toxicity test include zebrafish embryo survival, zebrafish embryo hatching, the number of tail swings of 28hpf zebrafish embryos in 1 minute, the heart rate of 72hpf zebrafish embryos in 1 minute, and the body length of 72hpf zebrafish.

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