Photodegradation reactor for purifying pollutants

Abstract

The invention provides a photodegradation reactor for purifying pollutants, and belongs to the technical field of environmental protection. The photodegradation reactor comprises: a filtration and purification zone, which adopts a three-stage filtration system to filter suspended solids and algae in inlet water; in the high-energy photocatalytic oxidation zone, algae and microorganisms in incoming water are killed by adopting an advanced oxidation system combining ultraviolet light and an oxidizing agent; in the algae-photocatalytic ball combined purification area, two kinds of composite algae and photocatalytic balls are combined to purify organic pollutants in the water body; and in the algae-eating area of the algae-filtering daphnia, the algae-filtering daphnia is cultivated to eat the composite algae entering the area, and the density of the algae in the outlet water is ensured to be lower than 1ug / L. According to the invention, a multi-stage and multi-region purification system is arranged, and a physical-advanced oxidation-biological combination mode is adopted, so that organic pollutants in a water body are efficiently degraded in a combined manner.

Description

Technical Field

[0001] The invention relates to the technical field of environmental protection, and in particular to a photodegradation reactor for purifying pollutants. Background Art

[0002] New antibiotic and hormone pollutants are a sub-area of ​​new pollutants, usually coming from wastewater in the fields of medical care, household breeding, agricultural breeding, etc. The new antibiotic pollutants in these wastewaters mainly include a variety of antibiotic drug residues and metabolites produced by antibiotics. These new antibiotic pollutants have strong antibacterial effects and are prone to cause bacterial resistance, posing a potential threat to human health and the environment. Effectively purifying new antibiotic pollutants in wastewater has become an urgent environmental protection task. There are tens of thousands of chemical substances in production and use, but there is little specific data on their hazards, and there is no legal basis to require companies to conduct hazard identification. In addition, my country has not yet systematically carried out environmental surveys, monitoring and environmental assessments of chemical substances, and the overall environmental risk base is unclear.

[0003] In order to reduce the impact of antibiotics on the ecological environment, various research projects have been carried out at home and abroad on the removal of antibiotic pollutants in water bodies. At present, the commonly used treatment methods for removing antibiotics from water bodies are physical, chemical and biological methods, as shown below:

[0004] (1) Physical methods: The physical methods used to remove antibiotics mainly include activated carbon adsorption, sand filtration and membrane filtration. The principle is mainly to reduce the concentration of antibiotics in wastewater through adsorption, ion exchange and other effects.

[0005] A. Activated carbon adsorption method: As a mature physical method, this method has the characteristics of no by-products, low energy consumption, and reusability. There is a certain positive correlation between the activated carbon concentration and the removal effect of antibiotics, but due to the high cost of activated carbon adsorption and the possibility of secondary pollution, this method is not widely used in antibiotic wastewater; USEPA believes that activated carbon adsorption is the best method for removing endocrine disruptors so far, but it has no removal effect on drugs with high water solubility and high polarity. SNY-DERA et al. believe that although activated carbon adsorption is effective for most environmental hormones, it is difficult to handle after adsorption, and due to economic and management difficulties, it is still not fully promoted.

[0006] B. Sand filtration: With the continuous development and progress of filter technology, sand filtration is increasingly used in sewage treatment. Nakada et al. used sand filtration to treat antibiotic wastewater. The results showed that the method had a general effect on the removal of antibiotics, with a removal rate of less than 50%.

[0007] C. Membrane filtration: Membrane filtration is mainly divided into reverse osmosis, ultrafiltration and nanofiltration, and its working principle is the interception of molecules. Yoon et al. found that membrane filtration has a better removal effect on some PPCPs when removing PPCPs by nanofiltration and ultrafiltration, and the study showed that there is a certain correlation between membrane pore size and antibiotic removal rate. Due to the high cost of this method, it is not widely used in antibiotic wastewater treatment.

[0008] (2) Chemical method: The chemical methods currently used for antibiotic wastewater treatment mainly include coagulation sedimentation method, chemical oxidation method, etc.

[0009] A. Coagulation and sedimentation method: In the treatment of pharmaceutical wastewater, coagulation and sedimentation method is widely used. It has a certain removal effect on antibiotic wastewater containing culture medium components (mainly in colloidal form). Zhang Xin et al.

[88] The research shows that the removal rate of some antibiotics by this method is about 40%. The research of Mccarthy et al. shows that flocculants can increase the removal rate of PPCPs by 4%-13%. The overall treatment effect of this method on antibiotic wastewater is average and can be used as a sewage pretreatment process.

[0010] B. Chemical oxidation method: Oxidation technology is an effective means to treat high-concentration maleic degradation wastewater. At present, chemical oxidation method has been widely used in the treatment of pharmaceutical wastewater. Among them, oxidation method is widely used in water disinfection and sewage deep treatment. For the treatment of PPCPs, oxidation method has been studied to a certain extent. Chamberlain et al. used chlorine as an oxidant to remove PPCPs and found that the removal effect was weak. Ozone oxidation is another commonly used chemical oxidation method. Ozone directly oxidizes and removes pollutants by generating an oxidizing substance hydroxyl free radical with water. Nakada et al. used ozone method to treat antibiotic wastewater, and the antibiotic removal rate was above 80%. When TiO2 was used as a catalyst, the removal rate was even higher. Although chemical oxidation method has a high removal rate and strong pertinence for antibiotics, it will produce intermediates with biological toxicity and has a high treatment cost. It is not the best treatment method for antibiotic wastewater.

[0011] (3) Biological method: Biological methods for treating antibiotic wastewater generally include activated sludge method, artificial wetland, etc. Biological method mainly refers to the structure of antibiotic residues changed by the action of microorganisms, and the antibiotic residues are degraded from macromolecular compounds to small molecular compounds, and finally become H2O and CO2, thus achieving harmless treatment of environmental pollution.

[0012] A. Activated sludge method: As the most commonly used biological treatment method, this method is widely used in the treatment of domestic sewage and industrial wastewater. Caballa et al. used the activated sludge method to treat PPCPs wastewater containing antibiotics, and the removal rate was between 20% and 70%, which was not satisfactory. For the treatment of antibiotic wastewater, the activated sludge method has a long startup process and complex operation and management. In addition, since some antibiotics will be deposited in the activated sludge, it has a certain inhibitory effect on the activity of microorganisms. This method has great limitations.

[0013] In general, there have been some studies at home and abroad on the treatment of new pollutants such as antibiotics, but they are still relatively small and scattered, lacking a technical system with strong purification capabilities and low treatment costs. Summary of the invention

[0014] The purpose of the present invention is to provide a photodegradation reactor for purifying pollutants, which can effectively purify and degrade pollutants by setting a multi-level and multi-region structure and adopting biological + photocatalytic + ultraviolet light + chemical methods.

[0015] The technical solution of the present invention is achieved in this way:

[0016] The present invention provides a photodegradation reactor for purifying pollutants, comprising:

[0017] In the filtration and purification area, a three-stage filtration system is used to filter suspended solids and algae in the incoming water;

[0018] In the high-energy photocatalytic oxidation zone, an advanced oxidation system combining ultraviolet light and hydrogen peroxide kills algae and microorganisms in the incoming water. Five ultraviolet lamps are evenly arranged around the pool, and the operating power of a single lamp is 2KW.

[0019] The algae-photocatalytic ball combined purification area uses two kinds of composite algae and photocatalytic balls to purify organic pollutants in the water. The outer shell of this area is made of transparent glass, with algae introduction ports and vents on the top, aeration devices at the bottom, and LED lights around.

[0020] The algae-eating area is where algae-eating daphnia are cultivated to feed on the composite algae that enter this area, ensuring that the number of algae in the effluent water is less than 100 / ml. This area adopts a multi-layer filtration mode, with aeration at the bottom and air holes on the top, and 80-mesh nets are used in each connecting area.

[0021] As a further improvement of the present invention, the filtration and purification area includes three stages of filtration, the first stage filtration uses 2-4 stainless steel filter meshes with a mesh size of 0.5-1.5 cm, the second stage filtration uses 2-4 stainless steel filter meshes with a mesh size of 0.2-0.7 cm, and the third stage filtration uses activated carbon fiber with a pore size of 20-30 ppi.

[0022] As a further improvement of the present invention, the first-stage filtration uses a stainless steel mesh with a mesh diameter of 1 cm, with one mesh spaced 10 cm apart, for a total of 3 meshes; the second-stage filtration uses a stainless steel mesh with a mesh diameter of 0.5 cm, with one mesh spaced 10 cm apart, for a total of 3 meshes; the third-stage filtration uses activated carbon fiber with a pore size of 20-30 ppi and a thickness of 0.6 m.

[0023] As a further improvement of the present invention, the hydraulic retention time in the high-energy photocatalytic oxidation zone is not less than 1 minute.

[0024] As a further improvement of the present invention, the two types of composite algae in the algae-photocatalytic ball combined purification zone are Chlorella and Glechoma, the algae cell biomass is 80-120 mg / L, the photocatalytic ball is made of carbon fiber loaded with monoclinic scheelite-type bismuth vanadate, the loading mass ratio is 1:10-20, the depth of the algae-photocatalytic ball combined purification zone is 0.5-1.5m, LEDs are arranged around, the light intensity is set to 3000-7000lux, and an automatic light intensity sensing device is arranged at the bottom. When the light intensity is lower than 5000lux, the fluorescent lamps are started, and the fluorescent lamps are evenly arranged around the combined purification zone. The hydraulic retention time in this area is controlled at 2-4h.

[0025] As a further improvement of the present invention, the mass ratio of Chlorella to Dictyophyllum is 1:1-3.

[0026] As a further improvement of the present invention, the algae-photocatalytic ball combined purification zone degrades pollutants in accordance with the following pseudo-first-order reaction equation:

[0027] C t =C0×e -kt

[0028] Where: C t is the concentration of pollutants after degradation after t time; C0 is the initial concentration of pollutants; K is the degradation rate constant: 0.42d- 1 ; T is time, d.

[0029] As a further improvement of the present invention, the breeding density of the algae-filtering daphnia in the algae-filtering daphnia eating area is not less than 50 / L, an aeration system is set at the bottom, and a dissolved oxygen alarm system is set to ensure that the dissolved oxygen in the area is not less than 5 mg / L for 24 hours, and multiple layers of 80-mesh mesh are set for filtration to ensure that the algae density in the effluent water is 1ug / L.

[0030] The feeding rate of filter-dip algae and the concentration of the two algae foods are consistent with the following equation:

[0031] y=6.03×10 -5 x-0.001

[0032] Where y is the feeding rate ug / (ind·h), x is the algae density ug / L.

[0033] As a further improvement of the present invention, the photodegradation reactor for purifying pollutants is provided with a heat preservation and heating device to ensure that the temperature is 20-25°C.

[0034] The present invention has the following beneficial effects: the present invention sets up a multi-level and multi-region structure, adopts biological + photocatalytic + ultraviolet light + chemical methods, and combines physical-advanced oxidation-biological combination methods to efficiently purify and degrade pollutants, and also has a good purification and degradation effect on difficult-to-degrade pollutants such as antibiotics and hormones, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0036] Figure 1 A schematic diagram of the structure of a photodegradation reactor for purifying pollutants provided in an embodiment of the present invention;

[0037] Among them, 1. Filtration and purification system; 101. Primary filtration; 102. Secondary filtration; 103. Tertiary filtration; 2. High-energy photocatalytic oxidation zone; 3. Algae-photocatalytic ball combined purification zone; 4. Algae filtering and Daphnia pulex eating algae zone. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] like Figure 1, a photodegradation reactor for purifying pollutants, mainly including 4 components, the first part is a filtration purification area 1 (stainless steel structure), the filtration purification area includes three-stage filtration, the first-stage filtration 101 adopts a stainless steel filter mesh with a mesh diameter of 1 cm (3 layers), the second-stage filtration 102 adopts a 0.5 cm stainless steel filter mesh (3 layers), and the third-stage filtration 103 adopts activated carbon fiber (1 / 3 thickness); the second part is a high-energy photocatalytic oxidation area 2, which uses an advanced oxidation system composed of ultraviolet light and hydrogen peroxide to kill algae and microorganisms in the incoming water, and 5 ultraviolet lamps are evenly arranged around the pool body, and the operating power of a single lamp is 2KW; the third area is an algae-photocatalytic ball combined purification area 3, which uses two kinds of composite algae and photocatalytic balls to purify organic pollutants in the water body. The outer shell of this area is made of transparent glass, with an algae introduction port and a vent on the top, an aeration device on the bottom, and LED lights around. The fourth area is the algae-eating area 4, which mainly cultivates the composite algae that the algae-eating daphnia feed on to ensure that the number of algae in the effluent is less than 100 / ml. This area adopts a multi-layer filtration mode, with aeration at the bottom and vents on the top. Each connecting area uses an 80-mesh net. The entire system is equipped with insulation and heating devices to ensure that the temperature is 20-25℃.

[0040] The first part uses a stainless steel filtration and purification system 1, which mainly uses a three-stage filtration system to filter suspended matter and algae in the incoming water. The first-stage filtration 101 uses a stainless steel mesh with a mesh diameter of 1 cm, with a design interval of 10 cm, and a total of 3 paths. The second-stage filtration 102 uses a stainless steel mesh with a mesh diameter of 0.5 cm, with a design interval of 10 cm, and 3 paths, mainly filtering and purifying large suspended matter. The third-stage filtration 103 uses activated carbon fiber with a pore size of 25ppi and a thickness of 0.6m, which mainly absorbs small suspended particles and some nutrients in the water.

[0041] The second part is the high-energy photocatalytic oxidation zone 2, which uses ultraviolet light + hydrogen peroxide to disinfect and control algae in this area. The designed hydraulic retention time of this area is not less than 1 minute.

[0042] The third part is the algae-photocatalytic ball combined purification area 3, which uses two kinds of composite algae, namely Chlorella vulgaris and Glechoma gloeosporium (1:2), with an algae cell biomass of 80-120mg / L. The photocatalytic ball is made of carbon fiber loaded with monoclinic scheelite-type bismuth vanadate, with a loading mass ratio of 1:10-20. The depth of the algae-photocatalytic ball combined purification area is 1m, and an aeration device and a heating device are set at the bottom to maintain the temperature of the area stable at 25℃. LEDs are set around the area, and the light intensity is set to 5000lux. An automatic light intensity sensing device is set at the bottom. When the light intensity is lower than 5000lux, the fluorescent lamps are started. The fluorescent lamps are evenly arranged around the combined purification area. The hydraulic retention time of this area is controlled at 2-4h.

[0043] The degradation of new pollutants in this area conforms to the following pseudo-first-order reaction equation:

[0044] C t =C0×e -kt

[0045] Where: C t is the concentration of pollutants after degradation after t time; C0 is the initial concentration of pollutants; K is the degradation rate constant: 0.42d- 1 ; T is time, d.

[0046] The fourth part is the algae-eating area 4: This area mainly cultivates algae-eating daphnia to feed on Chlorella and Glechoma. The density of algae-eating daphnia is 150 / L, an aeration system is set at the bottom, and a dissolved oxygen alarm system is set to ensure that the dissolved oxygen in this area is not less than 5mg / L for 24 hours. A multi-layer 80-mesh filter is set to ensure that the algae density in the effluent is 1ug / L.

[0047] The feeding rate of filter-dip algae and the concentration of the two algae foods are consistent with the following equation:

[0048] y=6.03×10 -5 x-0.001

[0049] Where y is the feeding rate ug / (ind·h), x is the algae density ug / L.

[0050] The third part is the removal of organic matter by the combined action of algae and carbon fiber loaded with monoclinic scheelite-type bismuth vanadate in the algae-photocatalytic ball combined purification zone 3. The removal efficiency of SD (sulfonamide) and SM2 (sulfadimethoxine) by Glechoma reticulata is 26.59% and 42.71%, respectively, which is greater than the removal efficiency of SD (sulfonamide) and SM2 (sulfadimethoxine) by Chlorella vulgaris, which is 20.23% and 23.27%, respectively. It can be seen from Table 3 that the removal efficiency of SM2 (sulfadimethoxine) by g-C3N4 (carbon nitride) at three concentrations is greater than that of SD, and the removal efficiency of SM2 is as high as more than 90%, while the removal efficiency of SD increases with the increase of its concentration.

[0051] The combination of two kinds of green algae and g-C3N4 (carbon nitride) has a significant promoting effect on the removal of SAs (sulfonamide drugs) compared with algae alone (sulfonamide drug SAs include many types, and the present invention has made two types, SD and SM2); there is no significant change compared with the removal efficiency of g-C3N4 for SM2 (Table 1); compared with the removal efficiency of low and medium concentrations of g-C3N4 for SD, it is significantly increased (Table 1). The removal efficiency of HA for SM2 is greater than that for SD at three concentrations, and the removal efficiency of HA for SM2 and SD at medium concentration is the highest, which are 68.49% and 48.49%, respectively (Table 2). The combined action of two kinds of green algae and HA will inhibit the efficiency of algae in removing antibiotics. The removal efficiency of BiVO4 (bismuth vanadate) for SM2 and SD increases with the increase of concentration. At three concentrations, the combination of two green algae and BiVO4 significantly promoted the removal efficiency of SAs by algae alone and BiVO4 alone, which could be as high as more than 90%, and the removal efficiency of SAs by the group of Glechoma reticulum + BiVO4 was slightly higher than that of the group of Chlorella + BiVO4 (Table 3). The removal efficiency of Cu-TiO2 for SM2 was greater than that for SD (Table 4). The combination of two green algae and Cu-TiO2 can promote the removal of SAs by algae alone to a small extent. However, it is significantly different from the removal efficiency of SAs by Cu-TiO2 (copper-titanium dioxide): in Glechoma reticulum, the removal efficiency increased under low and medium concentrations of Cu-TiO2; in Chlorella, the removal efficiency decreased (Table 4). In summary, the removal efficiency of the four photocatalysts for SAs is as follows: g-C3N4>BiVO4>HA (humic acid)>Cu-TiO2; the photocatalysts that play an active role in the removal of SAs by Chlorella and Glechoma are: g-C3N4, BiVO4 and Cu-TiO2; the effects of algae combined with different photocatalysts on the removal of SAs are different. The photocatalysts that play an active role in the removal of SM2 and SD by the combined system of Chlorella are BiVO4; g-C3N4 and BiVO4, while the photocatalysts that play an active role in the removal of SM2 and SD by the combined system of Glechoma are BiVO4 and Cu-TiO2; g-C3N4, BiVO4 and Cu-TiO2 (Tables 1 to 8).

[0052] Table 1 Removal efficiency of SM2 by g-C3N4 alone and in combination with two algae

[0053]

[0054] Table 2 Removal efficiency of SM2 by HA alone and in combination with two algae

[0055]

[0056]

[0057] Table 3 Removal efficiency of SM2 by BiVO4 alone and in combination with two algae

[0058] Group <![CDATA[BiVO4]]> +Chlorella +Dictyophora Low concentration group 71.95％ 99.19％ 99.41％ Medium concentration group 74.42％ 96.03％ 99.44％ High concentration group 93.16％ 97.50％ 99.11％

[0059] Table 4 Removal efficiency of SM2 by Cu-TiO2 alone and in combination with two algae

[0060] Group <![CDATA[Cu-TiO2]]> +Chlorella +Dictyophora Low concentration group 43.49％ 29.94％ 61.39％ Medium concentration group 49.14％ 37.12％ 70.07％ High concentration group 81.29％ 55.26％ 78.86％

[0061] Table 5 Removal efficiency of SD by g-C3N4 alone and in combination with two algae

[0062] Group <![CDATA[g-C3N4]]> +Chlorella +Dictyophora Low concentration group 74.45％ 93.91％ 91.09％ Medium concentration group 88.81％ 96.91％ 97.43％ High concentration group 95.70％ 97.42％ 97.63％

[0063] Table 6 Removal efficiency of SD by HA alone and in combination with two algae

[0064] Group HA +Chlorella +Dictyophora Low concentration group 41.73％ 7.34％ 25.93％ Medium concentration group 48.49％ 12.81％ 23.78％ High concentration group 43.38％ 5.70％ 16.92％

[0065] Table 7 Removal efficiency of SD by BiVO4 alone and in combination with two algae

[0066] Group <![CDATA[BiVO4]]> +Chlorella +Dictyophora Low concentration group 66.33％ 93.32％ 96.53％ Medium concentration group 82.60％ 95.60％ 99.17％ High concentration group 97.49％ 98.59％ 99.22％

[0067] Table 8 Removal efficiency of SD by Cu-TiO2 alone and in combination with two algae

[0068] Group <![CDATA[Cu-TiO2]]> +Chlorella +Dictyophora Low concentration group 22.91％ 19.58％ 27.60％ Medium concentration group 23.86％ 27.12％ 37.45％ High concentration group 58.29％ 47.59％ 49.00％

[0069] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photodegradation reactor for purifying pollutants, It is characterized in that include: In the filtration and purification area, a three-stage filtration system is used to filter suspended solids and algae in the incoming water; The high-energy photocatalytic oxidation zone uses an advanced oxidation system combining ultraviolet light and hydrogen peroxide to kill algae and microorganisms in the incoming water. Five ultraviolet lamps are evenly arranged around the pool, and the operating power of a single lamp is 2KW. The algae-photocatalytic ball combined purification area uses two kinds of composite algae and photocatalytic balls to purify organic pollutants in the water. The shell of the algae-photocatalytic ball combined purification area is made of transparent glass, with an algae introduction port and a vent on the top, an aeration device at the bottom, and LED lights around it. The algae-eating area for filtering algae is used to cultivate the composite algae that filter algae daphnia feed on, ensuring that the number of algae in the effluent water is less than 100 / ml; the algae-eating area for filtering algae adopts a multi-layer filtration mode, aeration is arranged at the bottom, air holes are arranged on the top, and 80-mesh nets are used in each connecting area.

2. The photodegradation reactor for purifying pollutants according to claim 1, It is characterized in that The filtration and purification area includes three stages of filtration. The first stage filtration uses 2-4 stainless steel filter meshes with a mesh size of 0.5-1.5 cm, the second stage filtration uses 2-4 stainless steel filter meshes with a mesh size of 0.2-0.7 cm, and the third stage filtration uses activated carbon fibers with a pore size of 20-30 ppi.

3. The photodegradation reactor for purifying pollutants according to claim 2, It is characterized in that The first-stage filtration uses a stainless steel mesh with a mesh diameter of 1 cm, with a spacing of 10 cm, and a total of 3 layers are designed. The second-stage filtration uses a stainless steel mesh with a mesh diameter of 0.5 cm, with a spacing of 10 cm, and a total of 3 layers are designed. The tertiary filtration uses activated carbon fiber with a pore size of 20-30ppi and a thickness of 0.6m.

4. The photodegradation reactor for purifying pollutants according to claim 1, It is characterized in that The hydraulic retention time in the high-energy photocatalytic oxidation zone is not less than 1 minute.

5. The photodegradation reactor for purifying pollutants according to claim 1, It is characterized in that The two types of composite algae in the algae-photocatalytic ball combined purification area are Chlorella and Glechoma, the algae cell biomass is 80-120 mg / L, the photocatalytic ball is made of carbon fiber loaded with monoclinic scheelite-type bismuth vanadate, and the loading mass ratio is 1:10-20. The depth of the algae-photocatalytic ball combined purification area is 0.5-1.5m, LEDs are arranged around, the light intensity is set to 3000-7000lux, and an automatic light intensity sensing device is arranged at the bottom. When the light intensity is lower than 5000lux, the fluorescent lamps are started. The fluorescent lamps are evenly arranged around the combined purification area, and the hydraulic retention time in this area is controlled at 2-4h.

6. The photodegradation reactor for purifying pollutants according to claim 5, It is characterized in that The mass ratio of Chlorella vulgaris to Dictyophyllum is 1:1-3.

7. The photodegradation reactor for purifying pollutants according to claim 5, It is characterized in that The algae-photocatalytic ball combined purification area conforms to the following pseudo-first-order reaction equation for pollutant degradation: C t =C 0 ×e -kt Where: C t is the concentration of pollutants after degradation after t time; C 0 is the initial concentration of pollutants; K is the degradation rate constant: 0.42d -1 ; T is time, d.

8. The photodegradation reactor for purifying pollutants according to claim 1, It is characterized in that The algae-eating area has a cultivation density of no less than 50 daphnia per liter, an aeration system is provided at the bottom, and a dissolved oxygen alarm system is provided to ensure that the dissolved oxygen in the area is no less than 5 mg per liter for 24 hours, and multiple layers of 80-mesh filtration are provided to ensure that the algae density in the effluent water is 1 ug per liter. The feeding rate of filter-dip algae and the concentration of the two algae foods are consistent with the following equation: y=6.03×10 -5 x-0.001 Where: y is the feeding rate ug / (ind·h), x is the algae density ug / L.

9. The photodegradation reactor for purifying pollutants according to claim 1, It is characterized in that The photodegradation reactor for purifying pollutants is provided with heat preservation and heating devices to ensure the temperature is 20-25°C.

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