A circulating reflux type integrated ultraviolet oxidation disinfection system and operation method

Abstract

The application belongs to the technical field of water treatment, and particularly relates to a circulating backflow type integrated ultraviolet oxidation disinfection system and a running method thereof, which comprises a water inlet module, a circulating water tank and a water outlet module. A mixing circulating pump and a valve are arranged between the water inlet module and the circulating water tank to communicate the water inlet module and the circulating water tank. The circulating water tank is connected with a mixing circulating backflow system. The mixing circulating backflow system is connected with an ultraviolet reaction module. The ultraviolet reaction module is connected with a dosing system for dosing a disinfecting oxidant. Valves and flow meters are arranged between the ultraviolet reaction module and the circulating water tank to communicate the ultraviolet reaction module and the circulating water tank. Valves and flow meters are arranged between the ultraviolet reaction module and the water outlet module to communicate the ultraviolet reaction module and the water outlet module. The application can achieve good disinfection effect on pathogenic microorganisms, almost no associated disinfection by-products are generated, and the reproduction of pathogenic microorganisms can be effectively reduced.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically a circulating reflux integrated ultraviolet oxidation disinfection system and its operation method. Background Technology

[0002] Domestic sewage harbors a large number of pathogenic microorganisms, including bacteria, viruses, parasites, and fungi. Once this sewage is discharged into natural water bodies, it will cause serious ecological damage to the environment. Although primary, secondary, or tertiary treatment significantly improves water quality and removes some pathogens, their concentrations remain high. Some pathogens can survive for extended periods in water bodies, soil, and on the surface of crops. Furthermore, when humans and animals come into contact with contaminated water sources, it can trigger the spread of diseases, posing a potential threat to public health and ecological health.

[0003] Disinfection is a crucial step in ensuring the safety of drinking water and reclaimed water. To prevent the spread of disease and protect the ecological environment, the "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants" (GB18918-2002) clearly stipulates that urban wastewater treatment plants should be equipped with disinfection facilities, and the effluent must undergo disinfection treatment in accordance with relevant standards. Currently, urban wastewater treatment plants in my country mainly implement either Class A or Class B standards. The Class A standard requires the fecal coliform count in the effluent to be below 1000 CFU / L, while the Class B standard requires the fecal coliform count in the effluent to be below 10000 CFU / L.

[0004] Currently, chlorination and ultraviolet (UV) disinfection are widely used disinfection technologies. Chlorination, as a common wastewater disinfection method, effectively kills pathogenic microorganisms; however, it generates harmful disinfection byproducts (DBPs) during the disinfection process, posing potential risks to human health and the environment. In contrast, UV disinfection, as a physical disinfection method, has advantages such as ease of operation and safety, achieving disinfection by destroying the genetic material of pathogenic microorganisms. However, UV disinfection cannot effectively prevent the regrowth of pathogenic microorganisms, potentially leading to photoreactivation. Therefore, UV / UV technology still involves the regeneration of disinfection byproducts, affecting water quality safety.

[0005] Peracetic acid (PAA) is a peroxide with strong oxidizing and disinfecting activity. Its oxidizing power is superior to chlorine and chlorine dioxide, and it has good disinfection effects on bacteria, viruses, fungi, and spores. It can effectively destroy the cell wall, cell membrane, and other cellular structures of bacteria, and damage the protein coat and nucleic acid of viruses, thus achieving highly efficient inactivation. Furthermore, peracetic acid produces fewer harmful byproducts during disinfection, and is considered by the International Water Association to be one of the most promising disinfectants. In recent years, peracetic acid has been increasingly used in water treatment disinfection, playing an important role in wastewater treatment. However, the use of peracetic acid alone can lead to the regeneration of pathogenic microorganisms and the co-existence of disinfection byproducts. In addition, persulfate technology can produce highly oxidizing SO4. .- It exhibits excellent removal effects on pathogenic microorganisms and disinfection byproducts, showing promising potential as a disinfection oxidant. However, the persulfate system alone has low efficiency in generating highly reactive species; therefore, it can be combined with ultraviolet disinfection processes to effectively remove disinfection pollutants.

[0006] Therefore, a circulating reflux integrated ultraviolet oxidation disinfection system and its operation method are proposed to address the above problems. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, at least one technical problem mentioned in the background art has been solved.

[0008] The technical solution adopted by this invention to solve its technical problem is as follows: A circulating reflux integrated ultraviolet oxidation disinfection system and its operating method, comprising an inlet module, a circulating water tank, and an outlet module; a mixing circulation pump and a valve connecting the inlet module and the circulating water tank are provided; the circulating water tank is connected to a mixing circulation reflux system; the mixing circulation reflux system is connected to an ultraviolet reaction module; the ultraviolet reaction module is connected to a disinfectant oxidant dosing system; a valve and a flow meter connecting the ultraviolet reaction module and the circulating water tank are provided; the ultraviolet reaction module and the outlet module... The water modules are connected by valves and flow meters. The inlet water enters the circulating water tank through a mixing circulation pump and valves. Once the water level in the circulating water tank reaches the preset height, the mixing circulation return system is activated. The wastewater in the circulating water tank enters the ultraviolet reaction module through the mixing circulation return system, and the disinfectant oxidant dosing system begins to add disinfectant oxidant to form a mixed reaction solution. The mixed reaction solution then flows out of the ultraviolet reaction module and passes through the flow distribution system. Part of it flows back to the circulating water tank, and the other part is discharged from the outlet water module. The flow distribution system flexibly controls the flow rates of the inlet water, outlet water, circulating pump, and dosing system according to the water quality and quantity.

[0009] Preferably, the circulating water tank is equipped with either a baffle plate or a stirring system to ensure thorough mixing of wastewater and return water in the return system.

[0010] Preferably, the circulating water tank has a size of 2-4m. 3 The circulating water tank is connected to an outlet module and an inlet module. A sensor is installed in the circulating water tank to adjust the inlet and outlet water flow. When the water level in the circulating water tank is below 2m... 3 The water outlet module and circulating water pump will automatically shut down when the liquid level is above 4m. 3 The water inlet module automatically shuts off;

[0011] Preferably, to ensure sufficient mixing and mass transfer of wastewater and chemicals in the pipeline, according to Reynolds' formula, the flow rate of the mixing circulation pump needs to be greater than 1.8 m³ / s. 3 / h: Set baffles in the ultraviolet reaction module to ensure the mixing and mass transfer effect of wastewater and reagent;

[0012] Preferably, the ultraviolet reaction module is an ultraviolet reactor, which includes pipes with a diameter of 0.3-0.6m and a total folded length of 5-8m. One end of the ultraviolet reactor is built into a mixing circulation reflux system and is evenly distributed according to the volume of the ultraviolet reactor. The ultraviolet reactor consists of an ultraviolet lamp and an external quartz lamp sleeve. The even distribution of the ultraviolet reactor in the pipes can improve the uniformity of the reaction, so that the reactants are more evenly exposed to ultraviolet radiation in the ultraviolet reactor.

[0013] Preferably, the pipeline of the ultraviolet reactor is lined with an ultraviolet catalytic material, which is any one of titanium dioxide, zinc oxide, ferrous oxide, semiconductor nanomaterials, and materials with photocatalytic properties. Ultraviolet light can catalyze the reaction to produce active species such as hydroxyl radicals, thereby improving the disinfection effect of pathogenic microorganisms and disinfection by-products in the water plant, and effectively reducing the phenomenon of pathogenic microorganism regeneration and disinfection by-products.

[0014] Preferably, the UV dose in the UV reactor is automatically adjusted according to the turbidity of the water, with the turbidity of the influent being less than 5 NTU and the UV dose being 20-40 mJ / cm². 2 ;

[0015] Preferably, the disinfectant oxidant dosing system includes: a disinfectant oxidant storage tank (for storing the disinfectant oxidant), a flow meter, a discharge pump, and a controller. The disinfectant oxidant dosing method in the system can be either continuous flow dosing or batch dosing to save reagents; this allows for selection based on actual production needs.

[0016] Preferably, the method of adding the disinfectant oxidant is related to the concentration of pathogenic microorganisms, the dosage of the disinfectant oxidant, and the hydraulic retention time. The flow ratio of influent wastewater to influent disinfectant oxidant is set at 50:1-80:1, the dosage of the disinfectant oxidant is 5-10 mg / L, and the hydraulic retention time of wastewater and reagent in the ultraviolet reaction module is 2-12 min.

[0017] When the concentration of pathogenic microorganisms is less than 10 4 CFU / ml, using a sequential batch dosing method, with a disinfectant oxidant dosage of 5-10 mg / L, a batch dosing interval of 3-5 min, and a wastewater and reagent residence time of 8-12 min in the UV reaction module;

[0018] When the concentration of pathogenic microorganisms is greater than 10 4 CFU / ml, using a continuous flow dosing method, with a disinfectant oxidant dosage of 2-5 mg / L, and a residence time of wastewater and reagent in the UV reaction module of 2-8 min;

[0019] The types of disinfectant oxidants include, but are not limited to, peracetic acid, persulfate, perdisulfate, and chloramine. Among them, peracetic acid or persulfate is preferred as the disinfectant oxidant.

[0020] This invention provides a circulating reflux integrated ultraviolet oxidation disinfection system and its operation method, which is applied to a circulating reflux integrated ultraviolet oxidation disinfection system and its operation method. The method includes the following steps:

[0021] S1: First, the water inlet module enters the circulating water tank through the mixing circulation pump and valve;

[0022] S2: Once the water level in the circulating water tank reaches the preset level, the mixing and circulating return system will be activated.

[0023] S3: Subsequently, the sewage in the circulating water tank enters the ultraviolet reaction module through the mixed circulation reflux system, and the disinfectant oxidant dosing system begins to add disinfectant oxidant to form a mixed reaction solution;

[0024] S4: Then, after the mixed reaction solution flows out of the UV reaction module, it passes through the flow distribution system. Part of it flows back to the circulating water tank, and the other part is discharged from the outlet module. The flow distribution system flexibly controls the flow of the inlet water, outlet water, circulating pump and dosing system according to the water quality and quantity.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. The circulating reflux integrated ultraviolet oxidation disinfection system and operation method described in this invention is an integrated device that can effectively save energy and occupy space, has a high degree of freedom of movement, and is suitable for wastewater disinfection treatment or pretreatment in various occasions such as waterworks and hospital medical wastewater.

[0027] 2. The circulating reflux integrated ultraviolet oxidation disinfection system and operation method described in this invention are circulating reflux operation, which can effectively improve the mass transfer effect of sewage, disinfection oxidant and ultraviolet light source, increase the generation of active species and enhance the disinfection effect; the disinfection oxidant dosing system can adopt continuous flow or multi-point dosing sequential batch operation, which can save the amount of reagents to a certain extent.

[0028] 3. The circulating integrated ultraviolet oxidation disinfection system and operation method described in this invention can reasonably select the sewage circulation flow rate, retention time, disinfectant concentration and dosing method according to the water quality characteristics and project requirements. It has a high degree of operability and certain economic benefits.

[0029] 4. The circulating reflux integrated ultraviolet oxidation disinfection system and operation method described in this invention can achieve good disinfection effect on pathogenic microorganisms, and there are almost no associated disinfection by-products, which can effectively reduce the regeneration of pathogenic microorganisms. Attached Figure Description

[0030] The invention will now be further described with reference to the accompanying drawings.

[0031] Figure 1 This is a schematic diagram of the operation process of a circulating reflux integrated ultraviolet oxidation disinfection system in this invention;

[0032] Figure 2 This is a schematic diagram of the circulation pipeline in this invention;

[0033] Figure 3 This is a flowchart of the circulating reflux integrated ultraviolet oxidation disinfection system and its operation method.

[0034] Figure 4 The graph shows the effect of peracetic acid dosage on the logarithmic inactivation rate of total coliform bacteria.

[0035] Figure 5 A comparison chart showing the generation of DBPs in peracetic acid / UV and sodium hypochlorite / UV disinfection processes.

[0036] In the diagram: 1. Inlet water module; 2. Circulating water tank; 3. Outlet water module; 4. Mixed circulation reflux system; 5. Ultraviolet reaction module; 51. Ultraviolet lamp; 52. External quartz lamp cover; 53. Ultraviolet catalytic material; 61. Disinfection oxidant storage tank; 62. Controller. Detailed Implementation

[0037] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0038] like Figures 1 to 2 As shown in the embodiment of the present invention, an integrated ultraviolet oxidation disinfection system and its operation method with a circulating reflux system includes an inlet module 1, a circulating water tank 2, and an outlet module 3. A mixing circulation pump and valve are provided between the inlet module 1 and the circulating water tank 2, connecting them. The circulating water tank 2 is connected to a mixing circulation reflux system 4, which is connected to an ultraviolet reaction module 5. The ultraviolet reaction module 5 is connected to a disinfection oxidant dosing system. A valve and flow meter are provided between the ultraviolet reaction module 5 and the circulating water tank 2, and a valve and flow meter are provided between the ultraviolet reaction module 5 and the outlet module 3. During operation, the inlet module 1 enters the circulating water tank 2 through the mixing circulation pump and valve. After the water volume in the circulating water tank 2 reaches a preset liquid level, the mixing circulation reflux system 4 is activated. Wastewater in the circulating water tank 2 enters the ultraviolet reaction module 5 through the mixing circulation reflux system 4, and the disinfection oxidant dosing system begins to add disinfection oxidant to form a mixture. The reaction solution, after flowing out of the UV reaction module 5, is mixed and distributed through a flow distribution system. Part of the solution flows back to the circulating water tank 2, while the other part is discharged from the effluent module 3. The flow distribution system flexibly controls the flow rates of the inlet, outlet, circulating pump, and dosing system based on water quality and quantity. This invention is an integrated device that effectively saves energy and floor space, has a high degree of mobility, and is suitable for wastewater disinfection or pretreatment in various settings such as waterworks and hospital medical wastewater. The circulating operation effectively improves the mass transfer between wastewater, disinfectant oxidant, and UV light source, increasing the generation of active species and enhancing the disinfection effect. The disinfectant oxidant dosing system can operate continuously or in a multi-point batch operation, saving on reagent dosage to some extent. The wastewater circulation flow rate, residence time, disinfectant oxidant concentration, and dosing method can be rationally selected based on water quality characteristics and project requirements. It is highly operable, has certain economic benefits, and provides good disinfection for pathogenic microorganisms with almost no associated disinfection byproducts, effectively reducing the regeneration of pathogenic microorganisms.

[0039] Furthermore, the circulating water tank 2 is equipped with either a baffle plate (not shown in the figure) or a stirring system (not shown in the figure) to ensure that the sewage and return water in the return system are fully mixed.

[0040] Furthermore, the specifications of the circulating water tank 2 are 2-4m. 3 The circulating water tank 2 is connected to the water outlet module 3 and the water inlet module 1. A sensing device (not shown in the figure) is installed in the circulating water tank 2 to flexibly adjust the water inlet and outlet conditions. When the water level in the circulating water tank 2 is below 2m...3 The water outlet module 3 and the circulating water pump will automatically shut off when the liquid level is above 4m. 3 The water inlet module 1 shuts off automatically.

[0041] Furthermore, to ensure thorough mixing and mass transfer of wastewater and chemicals in the pipeline, according to Reynolds' formula, the flow rate of the mixing circulation pump needs to be greater than 1.8 m³ / s. 3 / h: A baffle (not shown in the figure) is set in the UV reaction module 5 to ensure the mixing and mass transfer effect of wastewater and reagent;

[0042] Furthermore, the ultraviolet reaction module 5 is an ultraviolet reactor, which includes pipes with a diameter of 0.3-0.6m and a total folded length of 5-8m. One end of the ultraviolet reactor is built into the mixing circulation reflux system 4 and is evenly distributed according to the volume of the ultraviolet reactor. The ultraviolet reactor consists of an ultraviolet lamp 51 and an external quartz lamp sleeve 52. During operation, the even distribution of the ultraviolet reactor in the pipes can improve the uniformity of the reaction, so that the reactants are more evenly exposed to ultraviolet radiation in the ultraviolet reactor.

[0043] Furthermore, the pipeline of the ultraviolet reactor is lined with ultraviolet catalytic material 53, which can be any one of titanium dioxide, zinc oxide, ferrous oxide, semiconductor nanomaterials, and materials with photocatalytic properties. During operation, ultraviolet light can catalyze the reaction to produce active species such as hydroxyl radicals, thereby improving the disinfection effect of pathogenic microorganisms and disinfection by-products in the water plant, and effectively reducing the phenomenon of pathogenic microorganism regeneration and disinfection by-products.

[0044] Furthermore, the UV dose in the UV reactor is automatically adjusted according to the turbidity of the water, ensuring that the turbidity of the influent is less than 5 NTU and the UV dose is 20-40 mJ / cm³. 2 ;

[0045] Furthermore, the disinfectant oxidant dosing system includes: a disinfectant oxidant storage tank 61 (for storing disinfectant oxidant), a flow meter, a discharge pump, and a controller 62. The disinfectant oxidant dosing method in the disinfectant oxidant dosing system can be either continuous flow dosing or batch dosing to save reagents; during operation, it is convenient to select and use according to the actual wastewater treatment needs.

[0046] Furthermore, the method of adding the disinfectant oxidant is related to the concentration of pathogenic microorganisms, the dosage of the disinfectant oxidant, and the hydraulic retention time. The flow ratio of influent wastewater to influent disinfectant oxidant is set at 50:1-80:1, the dosage of disinfectant oxidant is 5-10 mg / L, and the hydraulic retention time of wastewater and reagent in the ultraviolet reaction module 5 is 2-12 min.

[0047] When the concentration of pathogenic microorganisms is less than 104 CFU / ml, using a sequential batch dosing method, with a disinfectant oxidant dosage of 5-10 mg / L, a batch dosing interval of 3-5 min, and a wastewater and reagent residence time of 8-12 min in UV reaction module 5;

[0048] When the concentration of pathogenic microorganisms is greater than 10 4 CFU / ml, using a continuous flow dosing method, with a disinfectant oxidant dosage of 2-5 mg / L, and a residence time of wastewater and reagent in UV reaction module 5 of 2-8 min;

[0049] This invention also provides a circulating reflux integrated ultraviolet oxidation disinfection system and its operation method, which are applied in the circulating reflux integrated ultraviolet oxidation disinfection system and its operation method. The method includes the following steps:

[0050] S1: First, the water inlet module 1 enters the circulating water tank 2 through the mixing circulation pump and valve;

[0051] S2: Once the water level in the circulating water tank 2 reaches the preset liquid level, the mixing and circulating return system 4 will be activated.

[0052] S3: Subsequently, the sewage in the circulating water tank 2 enters the ultraviolet reaction module 5 through the mixed circulation return system 4, and the disinfection oxidant dosing system begins to add disinfection oxidant to form a mixed reaction liquid;

[0053] S4: Then the mixed reaction solution flows out of the ultraviolet reaction module 5 and passes through the flow distribution system. Part of it flows back to the circulating water tank 2, and the other part is discharged from the outlet module 3. The flow distribution system flexibly controls the flow of water inlet, water outlet, circulating pump and dosing system according to water quality and quantity.

[0054] To make the present invention more apparent and understandable, preferred embodiments and comparative examples are described in detail below with reference to the accompanying drawings:

[0055] Example 1:

[0056] This embodiment uses secondary effluent from the biological treatment stage of a wastewater treatment plant in Suzhou. The water quality is as follows: pH 6.32–7.28, color 9.0–15.0 times, color 3 NTU, COD 3–21 mg / L, ammonia nitrogen 0.13–1.02 mg / L, total nitrogen 4.12–12.65 mg / L, total phosphorus 0.15–0.36 mg / L, and fecal coliform count (1.2–4.5) x 10⁻⁶. 5 MPN / L. Set the UV dose to 20 mJ / cm². 2The residence time in UV reaction module 5 was 2 minutes. Peracetic acid was added in a continuous flow manner. The effect of the circulating reflux integrated UV / peracetic acid disinfection system on total coliform bacteria was investigated at different peracetic acid concentrations of 0-10 mg / L. The results are as follows: Figure 1 As shown, UV alone is not very effective against Escherichia coli. When the concentration of peracetic acid is increased from 2 mg / L to 4, 6, 8, and 10 mg / L, the logarithmic inactivation rate of total coliforms increases from 1.40-1g to 1.45-1g, 2.23-1g, 2.42-1g, 2.72-1g, and 3.01-1g, respectively.

[0057] Example 2:

[0058] This embodiment uses secondary effluent from the biological treatment stage of a wastewater treatment plant in Suzhou, with effluent quality identical to that in Example 1. To verify the long-term stability of this system, it was operated continuously for 15 days under the following conditions to investigate its removal efficiency against pathogenic microorganisms such as total coliforms, fecal coliforms, and Hercules coli. The operating conditions were: UV light dose set at 20 mJ / cm². 2 The peracetic acid dosage was 15 mg / L, the sequential batch dosing interval was 3-5 min, and the residence time of wastewater and reagent in UV reaction module 5 was 8-12 min. After 15 days of continuous operation, the influent and effluent results are shown in Table 1. Pathogenic microorganisms such as total Escherichia coli, fecal Escherichia coli, and Hercules coli were all well removed, and the relevant indicators were below the detection limit.

[0059] Comparative Example 1:

[0060] This comparative example uses secondary effluent from the biological treatment stage of a wastewater treatment plant in Suzhou, with effluent quality identical to that in Example 1. This comparative example tests typical disinfection byproducts in the raw water and the peracetic acid / UV disinfection effluent, and compares them with sodium hypochlorite / UV technology. Operating conditions: UV dose set at 20 mJ / cm². 2 The dosage of the reagent (peracetic acid or sodium hypochlorite) was 15 mg / L, and the residence time of the wastewater and reagent in the UV reaction module 5 was 8 min. The results are shown in the figure below. By comparison, it can be found that the traditional sodium hypochlorite / UV disinfection process significantly increases the concentration of trihalomethanes (HAAs) and haloacetic acids (THMs) in the effluent. The peracetic acid / UV disinfection process has a smaller impact on the concentration of HAAs and THMs in the effluent, resulting in higher water quality safety.

[0061] Table 1: Changes in total coliforms, fecal coliforms, and Escherichia coli before and after PAA / UV disinfection:

[0062]

[0063]

[0064] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for operating a recirculating backflow integrated ultraviolet oxidative disinfection system, comprising: The method comprises the following steps: S1: firstly, the water module (1) enters into the circulating water tank (2) through the mixing circulating pump and the valve; S2: after the water volume of the circulating water tank (2) reaches the preset liquid level height, the mixing circulating backflow system (4) is started; S3: then, the sewage in the circulating water tank (2) enters the ultraviolet reaction module (5) through the mixing circulating backflow system (4), and the disinfecting oxidant adding system starts to add disinfecting oxidant to form a mixed reaction solution; S4: then, the mixed reaction solution flows out of the ultraviolet reaction module (5) and passes through the flow distribution system, part of which flows back to the circulating water tank (2), and the other part is discharged from the water outlet module (3); the flow distribution system flexibly controls the flow of the water inlet, the water outlet, the mixing circulating pump and the dosing system according to the water quality and water volume; The disinfecting oxidant adding system can add the disinfecting oxidant in any one of the continuous flow adding mode and the sequence batch adding mode for saving the disinfecting oxidant; The adding mode of the disinfecting oxidant is related to the concentration of the pathogenic microorganism, the adding amount of the disinfecting oxidant and the hydraulic retention time; the flow ratio of the inlet wastewater to the disinfecting oxidant is 50:1-80:1, the adding amount of the disinfecting oxidant is 2-10 mg / L, and the hydraulic retention time of the wastewater and the disinfecting oxidant in the ultraviolet reaction module (5) is 2-12 min; When the concentration of pathogenic microorganisms is less than 10 4 CFU / ml, the disinfecting oxidant is added in a batch mode for multiple times, the dosage of the disinfecting oxidant is 5-10 mg / L, the interval time of batch addition is 3-5 min, and the residence time of the wastewater and the disinfecting oxidant in the UV reaction module (5) is 8-12 min. When the concentration of pathogenic microorganisms is greater than 10 4 When the concentration of pathogenic microorganisms is greater than 10 4 CFU / ml, the continuous flow medicament adding mode is adopted, the disinfection oxidant adding amount is 2-5 mg / L, and the residence time of wastewater and medicament in the ultraviolet reaction module (5) is 2-8 min. The disinfecting oxidant includes, but is not limited to, any one of peracetic acid, peroxymonosulfate, peroxymonosulfate, chloramine.

2. The integrated recirculating backflow ultraviolet oxidative disinfection system according to claim 1, wherein the method for operating the integrated recirculating backflow ultraviolet oxidative disinfection system comprises the following steps: The method comprises the following steps: ​ 3. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 2, characterized in that: The method comprises the following steps:

4. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 3, characterized in that: The circulating water tank (2) is 2-4m 3 The circulating water tank (2) is connected with the water outlet module (3) and the water inlet module (1), and the inductive device is arranged in the circulating water tank (2) to adjust the water inlet and outlet conditions.

5. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 4, characterized in that: To ensure the sufficient mixing and mass transfer of wastewater and reagent in the pipeline, according to the Reynolds formula, the flow of the mixing circulating pump needs to be greater than 1.8 m 3 / h: Baffles are arranged in the ultraviolet reaction module (5).

6. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 5, characterized in that: The circulating water tank (2) is arranged with any one of the baffle and the stirring system.

7. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 6, characterized in that: The ultraviolet reaction module (5) is an ultraviolet reactor, which comprises a pipeline with a diameter of 0.3-0.6 m and a total length of 5-8 m; the ultraviolet reactor is arranged in the mixing circulating backflow system (4) at one end and is evenly distributed according to the volume of the ultraviolet reactor; the ultraviolet reactor is composed of an ultraviolet lamp (51) and an additional quartz lamp sleeve (52).

8. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 7, characterized in that: The UV dose in the ultraviolet reactor is automatically adjusted according to the turbidity of the water quality, the turbidity of the inlet water is less than 5 NTU, and the dose of ultraviolet light is 20-40 mJ / cm 2 .

9. The recirculating backflow integrated ultraviolet oxidative disinfection system according to claim 8, characterized in that: The pipeline of the ultraviolet reactor is lined with ultraviolet catalytic material (53), which is any one of materials with photocatalytic properties. The disinfecting oxidant adding system comprises a disinfecting oxidant storage tank (61), a flow meter, a discharge pump and a controller (62).

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