Device and method for treating organic wastewater by light-electricity combined catalytic oxidation technology

Abstract

The invention discloses a device and a method for treating organic wastewater by a light-electricity combined catalytic oxidation technology, and belongs to the technical field of water treatment. The invention provides a device for treating organic wastewater by a photo-electric combined catalytic oxidation technology, which comprises a reaction tank, a circulating pump, an electro-catalytic reactor and a photo-reactor which are communicated in sequence, and the reaction tank is communicated with the photo-reactor to form a liquid flow loop; the photoreactor comprises a flow channel and an ultraviolet light source arranged in the flow channel; and the thickness of the flow channel is 10 to 30 mm. According to the device for treating the organic wastewater through the photo-electric combined catalytic oxidation technology, only liquid medicine containing chloride ions needs to be added, other agents do not need to be added, the defect that hydrogen peroxide and iron need to be added in an existing ultraviolet Fenton technology is overcome, no treatment residues are generated in the using process, and no solid waste is formed; and the added liquid medicine is low in cost and wide in source, so that the use cost of the medicament is greatly reduced.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, and more specifically, relates to an apparatus and method for treating organic wastewater using a photo-electro-catalytic oxidation technology. Background Technology

[0002] In recent years, with the rapid advancement of industrialization, the discharge of high-salinity organic wastewater from industries such as petrochemicals, pharmaceuticals, electroplating, and printing and dyeing has increased significantly. This type of wastewater not only contains high concentrations of recalcitrant organic matter but also exhibits high salinity (typically greater than 1% ≈ 1 g / L), posing a serious threat to the ecological environment and human health. Traditional water treatment processes (such as biological methods, physical adsorption methods, and membrane separation methods) generally suffer from high treatment costs, high energy consumption, and low treatment efficiency when treating high-salinity organic wastewater. Furthermore, membrane separation is prone to membrane fouling, and biological methods are susceptible to secondary pollution due to the inhibition of microbial activity caused by high salinity osmotic pressure, making it difficult to meet actual treatment needs.

[0003] Advanced oxidation technologies can generate highly oxidizing hydroxyl radicals ( ). Fenton oxidation technology, with its high oxidation-reduction potential reaching 2.8V (OH-), efficiently mineralizes organic matter, becoming one of the core technologies for treating high-salt organic wastewater. Among these technologies, Fenton oxidation, a classic advanced oxidation process, is widely used due to its simple reaction mechanism and high degradation efficiency. Fenton oxidation technology utilizes Fe... 2+ It reacts with hydrogen peroxide (H2O2) to produce OH can rapidly decompose recalcitrant organic compounds such as phenols, cyanides, and dyes. However, the application of traditional Fenton technology has significant limitations: firstly, the reaction needs to be carried out under acidic conditions (pH=2~3), and the narrow pH range increases the cost of acid-base adjustment in practical engineering; secondly, Fe... 2+ First, it easily hydrolyzes to form iron-containing sludge, generating solid waste pollution; second, a large amount of H2O2 needs to be continuously added during the reaction process, resulting in high reagent costs; third, in a high-salt environment, the Cl in the wastewater... - SO4 2- Anions will quench OH affects the oxidation efficiency of the Fenton reaction, thus limiting its application in high-salt wastewater.

[0004] To solve the above-mentioned defects of traditional Fenton technology, researchers have developed two types of improved processes: one type introduces electrode catalysis process to optimize the reaction system of traditional Fenton (electrocatalysis-Fenton technology). For example, the Chinese invention patent application with publication number CN102092820A discloses a double-tank double-effect photoelectric Fenton device, which realizes the synergy of electro-Fenton reaction and photoelectric catalysis by reducing O2 to H2O2 through carbon / iron composite material cathode, and improves the treatment efficiency of printing and dyeing wastewater, but its electrolysis energy consumption is relatively high, and in high-salt environment, the electrode material is easily corroded or scaled by high-salt wastewater, resulting in short service life of the electrode; the other type is to introduce ultraviolet light irradiation to intensify Fenton reaction (ultraviolet Fenton technology). For example, the Chinese invention patent application with publication number CN114835210A discloses a method for treating cyanide by coupling ultraviolet light with electrocatalysis, which can promote the breakage of metal cyanide and release free cyanide, which can be quickly oxidized to cyanate, and the introduction of ultraviolet light can increase the utilization rate of H2O2 by more than 30%. However, it still needs to add a certain amount of H2O2, and at the same time, the penetration ability of ultraviolet light in water is weak, especially in deep-colored high-salt organic wastewater, the penetration thickness of ultraviolet light is greatly reduced, resulting in low light utilization rate in the reaction system.

[0005] In summary, although the electrocatalysis-Fenton technology can reduce the addition of reagents, it has the problems of high energy consumption and easy failure of the electrode, and the ultraviolet Fenton technology can improve the utilization rate of H2O2, but is limited by the penetration of ultraviolet light, and the efficiency still needs to be improved, and H2O2 still needs to be continuously added; both of them cannot efficiently and economically treat high-salt organic wastewater. Therefore, it is of great significance to develop a device and method for efficiently and economically treating high-salt organic wastewater. SUMMARY

[0006] 1. Problem to be solved In view of the problem that the prior art cannot efficiently and economically treat high-salt organic wastewater, the present application provides a device for treating organic wastewater by photo-electric combined catalytic oxidation technology and a method for treating organic wastewater by photo-electric combined catalytic oxidation technology.

[0007] 2. Technical scheme In order to solve the above-mentioned problems, the technical scheme adopted by the present application is as follows: The first aspect of the present application provides a device for treating organic wastewater by photo-electric combined catalytic oxidation technology, which comprises: a reaction tank, a circulating pump, an electrocatalytic reactor and a photo reactor connected in sequence, and the reaction tank and the photo reactor are connected to form a liquid flow circuit; The electrocatalytic reactor comprises an electrolytic cell and an electrode arranged in the electrolytic cell; The photo reactor comprises a flow channel and an ultraviolet light source arranged in the flow channel; Among them, The wavelength of the ultraviolet light source comprises 180-185 nm and 250-260 nm; The irradiation intensity of the ultraviolet light source is 10-80 μW / cm²; The thickness of the flow channel is 10-30 mm.

[0008] It should be noted that the flow channel is a wastewater channel, and when the wastewater flows through, a water layer with a thickness of 10-30 mm is formed based on the thickness limitation of the flow channel. Under this thickness, the wastewater can be fully irradiated by the ultraviolet light, thus improving the utilization rate of the ultraviolet light and further improving the efficiency of the ultraviolet light in treating organic matter in the wastewater.

[0009] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the device for treating organic wastewater by the photo-electric combined catalytic oxidation technology further comprises a dosing barrel, which is in communication with the reaction tank and is used for adding a chlorine ion-containing liquid medicine into the reaction tank.

[0010] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the chlorine ion-containing liquid medicine comprises one or more of sodium chloride, potassium chloride, and calcium chloride solution.

[0011] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the anode material of the electrode comprises one or more of ruthenium iridium titanium, graphite, and diamond. The cathode material of the electrode comprises one or more of titanium, stainless steel, and graphite. The distance between the anode and the cathode is 5-20 mm.

[0012] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the anode material of the electrode is ruthenium iridium titanium.

[0013] It should be noted that the surface of the ruthenium iridium titanium anode is a composite coating of ruthenium and iridium metal oxides. Such oxides can serve as electrocatalytic active sites, greatly reducing the activation energy of the oxidation reaction in the electrolyte. The ruthenium iridium titanium anode realizes “directional selection” of the reaction through catalytic properties: in wastewater rich in chlorine ions, it preferentially catalyzes the chlorine evolution reaction to generate hypochlorous acid and active chlorine (•Cl) and other active species, having stronger organic matter degradation performance; in a low-chlorine system, it can catalyze the oxygen evolution reaction, accompanied by the generation of hydroxyl radicals, to achieve the degradation of organic matter.

[0014] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the device for treating organic wastewater by the photo-electric combined catalytic oxidation technology further comprises an adjusting tank. The adjusting tank is in communication with the reaction tank through a water inlet pump.

[0015] As a preferred embodiment of any of the technical solutions of the first aspect of the present application, the reaction tank is provided with a stirrer, a chlorine ion detector, and a magnetic float liquid level meter. The heat exchanger and the temperature sensor are arranged on the connecting passage of the reaction tank and the photo-reactor.

[0016] The second aspect of the present application provides a method for treating organic wastewater by photo-electric combined catalytic oxidation technology, comprising the following steps: S1: adjusting the concentration of chloride ions in the wastewater in the reaction tank to 10-15 g / L; S2: delivering the wastewater in the reaction tank to the electro-catalytic reactor, and performing electro-catalytic reaction for 1-3 min at a temperature of 40-60℃; delivering the wastewater in the electro-catalytic reactor to the flow channel of the photo-reactor to form a water layer with a thickness of 10-30 mm, and performing photolysis reaction under the action of ultraviolet light at a temperature of 40-60℃ for 30-60 s; S3: delivering the wastewater treated by the photo-reactor to the reaction tank, and repeating steps S1, S2 and S3 until the wastewater in the reaction tank meets the standard and is discharged.

[0017] It should be noted that the wastewater containing chloride ions generates hypochlorous acid, active chlorine, hydroxyl radicals and the like under the action of the electro-catalytic reactor, and then these active species realize efficient removal of organic matter in the wastewater in cooperation with the ultraviolet light in the photo-reactor. Meanwhile, the electro-catalytic reaction and the photolysis reaction are arranged to be performed alternately, which can utilize these active species to a greater extent and achieve better organic matter removal efficiency.

[0018] The "electro-catalytic reaction for 1-3 min" in step S2 can be realized by adjusting the single hydraulic retention time of the wastewater in the electro-catalytic reactor to 1-3 min, and the "photolysis reaction for 30-60 s" can be realized by adjusting the single hydraulic retention time of the wastewater in the photo-reactor to 30-60 s.

[0019] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, in step S1, a dosing barrel is used to add a chloride ion-containing liquid medicine to the reaction tank to adjust the concentration of chloride ions in the wastewater in the reaction tank. The chloride ion-containing liquid medicine comprises one or more of sodium chloride, potassium chloride and calcium chloride solution.

[0020] Further preferably, the chloride ion-containing liquid medicine is a sodium chloride solution.

[0021] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, the anode material of the electro-catalytic reaction comprises one or more of ruthenium, iridium and titanium, and the cathode material comprises one or more of titanium, stainless steel and graphite. The distance between the anode and the cathode is 5-20 mm.

[0022] The distance between the anode and the cathode is too small to cause short circuit, and is too large to cause insufficient wastewater treatment and poor electrocatalytic reaction effect.

[0023] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, the electrocatalytic reaction comprises: the current density is 20-25 mA / cm 2 ; and the voltage is 10-60 V.

[0024] It should be noted that, if the current density is too small, the electrocatalytic reaction driving force is insufficient, the amount of active species generated is small, and the reaction efficiency is low; if the current density is too large, the energy consumption is increased, the electrode loss is accelerated, and harmful by-products are easily generated, such as, under the action of too high current density, excessive oxidation leads to too high concentration of active oxygen species (OH 、 OOH), which is easy to react with Cl - and organic matter in the wastewater to generate halogenated disinfection by-products (DBPs) such as chloroform (CHCl3) and chlorophenol, or oxidation intermediates such as quinones and carboxylic acids, thereby increasing the biological toxicity of the wastewater.

[0025] As a preferred embodiment of any of the technical solutions of the second aspect of the present application, the photolysis reaction satisfies one or more of the following (i)-(iii) conditions: (i) the wavelength of the ultraviolet light simultaneously contains 180-185 nm and 250-260 nm; (ii) the irradiation intensity of the ultraviolet light is 10-80 μW / cm²; (iii) the thickness of the water layer subjected to the ultraviolet light is 10-30 mm.

[0026] As a preferred embodiment of any of the technical solutions of the third aspect of the present application, the salinity of the organic wastewater is 0-100 g / L.

[0027] Further preferably, the salinity of the organic wastewater is 0-60 g / L; Further preferably, the salinity of the organic wastewater is 1-60 g / L; Further preferably, the salinity of the organic wastewater is 2-60 g / L; Further preferably, the salinity of the organic wastewater is 5-60 g / L; Further preferably, the salinity of the organic wastewater is 1-30 g / L; Further preferably, the salinity of the organic wastewater is 5-30 g / L; Further preferably, the salinity of the organic wastewater is 10-30 g / L.

[0028] 3. Beneficial effects Compared with the prior art, the present application has the following beneficial effects: (1) The device for treating organic wastewater by photo-electric combined catalytic oxidation technology provided by the application has a special structure design in the flow channel of the photo reactor, so that the water layer subjected to light is thin, which is beneficial to improving the utilization rate of ultraviolet light in the photo reactor, and a high-intensity ultraviolet light source is used, so that the photolysis reaction is further strengthened, and the problems of insufficient light utilization and poor light treatment efficiency caused by weak penetration of ultraviolet light in water in the prior art are overcome.

[0029] (2) The device for treating organic wastewater by photo-electric combined catalytic oxidation technology provided by the application only needs to add a liquid medicine containing chlorine ions, and does not need to add other reagents, so that the shortcomings of the existing ultraviolet Fenton technology, i.e. the need to add hydrogen peroxide and iron, are overcome, and no treatment residue is generated during use, so that no solid waste is formed; and the liquid medicine added has low cost and wide sources, so that the use cost of reagents is greatly reduced. (3) The device for treating organic wastewater by photo-electric combined catalytic oxidation technology provided by the application uses ruthenium iridium titanium as an anode material, which has a directional selective catalytic effect in wastewater containing Cl - , preferentially catalyzes the chlorine evolution reaction, promotes the generation of active species such as hypochlorous acid and •Cl, effectively improves the treatment efficiency of organic wastewater, and has a synergistic effect between the added liquid medicine containing chlorine ions and the use of ruthenium iridium titanium as an anode material.

[0030] (4) The method for treating organic wastewater by photo-electric combined catalytic oxidation technology provided by the application controls a reasonable chlorine ion concentration and current density, so that the efficiency of wastewater treatment is ensured, and the overall cost of equipment operation and the maintenance cost in the later period are reduced; and the method for treating organic wastewater by photo-electric combined catalytic oxidation technology provided by the application uses a process method of synergistic treatment of photolysis reaction and electrocatalytic reaction, and also sets the electrocatalytic reaction and the photolysis reaction to alternately perform, so that efficient removal of organic matter can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is a schematic diagram of the device for treating organic wastewater by photo-electric combined catalytic oxidation technology in embodiment 1. Figure 2 It is a curve of the relationship between different chlorine ion concentrations and the removal of dimethyl sulfoxide in wastewater in embodiment 2. Figure 3 It is a curve of the relationship between different current densities and the removal of dimethyl sulfoxide in wastewater in embodiment 3. Figure 4 It is the removal of dimethyl sulfoxide in wastewater under the working modes of UV, electrocatalysis and photo-electric catalysis in embodiment 4. Figure 5 It is a liquid chromatogram of dimethyl sulfoxide in wastewater under different treatment times in embodiment 5.

[0032] Explanation of reference signs: 1, conditioning tank; 2, magnetic float liquid level meter; 3, water inlet pump; 4, reaction tank; 5, stirrer; 6, chloride ion detector; 7, circulating pump; 8, electro-catalytic reactor; 9, electrode; 10, photo-reactor; 11, temperature sensor; 12, heat exchanger; 13, dosing barrel; 14, dosing metering pump; 15, stirrer. DETAILED DESCRIPTION

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs.

[0034] Unless otherwise indicated, conventional conditions or manufacturer's recommendations were used in the examples. The reagents or instruments used are not specified by the manufacturer, and are all conventional products that can be purchased on the market.

[0035] Concentrations, amounts, and other numerical data can be presented herein in a range format. It is to be understood that such range format is used merely for the convenience and brevity and should be construed as having been followed to indicate that not only the numerical values explicitly recited are the only values to be considered, but that other values or sub-ranges of the values listed are also to be considered as if explicitly recited. For example, a range of about 1 to about 4.5 should be interpreted to include not only the explicitly recited limits of about 1 to about 4.5, but also the individual numbers such as 2, 3, and 4 and the sub-ranges such as 1-3, 2-4, etc. The same applies to ranges reciting only one numerical value, such as "less than about 4.5", which should be interpreted to include all of the above-referenced values and ranges. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described.

[0036] The application will be further described below with reference to specific examples.

[0037] Raw materials and instruments used in the examples Magnetic float liquid level meter: remote type magnetic float liquid level meter, Shanghai Automatic Instrument and Electrical Factory, model UQC-C10-W-R-1500-1.0; Ruthenium-iridium-titanium electrode plate: Suzhou Shulai Industrial Technology Co., Ltd., the specification used in Example 1 is 30x60mm, and the specification used in Example 5 is 600x1000mm; Mercury vapor lamp: Heraeus lamp, model QC10000 (ultraviolet light wavelength with 183nm and 254nm); Chloride ion detector: HACH chloride analyzer, model EZ3500; Online chemical oxygen demand (COD) detector: HACH, model COD-203A.

[0038] Embodiment 1 1. Device for treating organic wastewater by photo-electric combined catalytic oxidation technology As Figure 1 shown, the device for treating organic wastewater by photo-electric combined catalytic oxidation technology provided in the embodiment comprises a regulating tank 1, a reaction tank 4, a dosing barrel 13, an electro-catalytic reactor 8 and a photo-reactor 10. The regulating tank 1, the reaction tank 4, the electro-catalytic reactor 8 and the photo-reactor 10 are sequentially communicated, and the reaction tank 4 and the photo-reactor 10 are communicated to form a liquid flow loop. The regulating tank 1 and the reaction tank 4 are communicated through a water inlet pump 3, and the reaction tank 4 and the electro-catalytic reactor 8 are communicated through a circulating pump 7. Specifically: The regulating tank 1 is provided with a water inlet, a water outlet, a blowdown port at the bottom and an overflow port at the upper part. A magnetic flap liquid level meter 2 with a signal remote is also installed in the regulating tank 1, and the magnetic flap liquid level meter 2 is interlocked with a matching water inlet pump 3. The regulating tank 1 is communicated with the reaction tank 4 through the water inlet pump 3.

[0039] The reaction tank 4 is also provided with a charging port, an exhaust port, two water inlets, one water outlet and one water outlet. The reaction tank 4 is communicated with the dosing barrel 13 through the charging port, and the liquid medicine in the dosing barrel 13 can enter the reaction tank 4 from the charging port; the exhaust port of the reaction tank 4 is connected with an exhaust fan, which is used to exhaust the gas generated in the reaction process to reduce the safety hidden danger; The water outlet of the reaction tank 4 is communicated with the water inlet of the electro-catalytic reactor 8, and the circulating pump 7 is arranged on the pipeline between the water outlet of the reaction tank 4 and the water inlet of the electro-catalytic reactor 8. The wastewater in the reaction tank 4 enters the electro-catalytic reactor 8 through the circulating pump 7 from the water outlet thereof; the water outlet of the electro-catalytic reactor 8 is communicated with the water inlet of the photo-reactor 10, and the water outlet of the photo-reactor is communicated with the other water inlet of the reaction tank 4. The wastewater in the electro-catalytic reactor 8 flows into the photo-reactor 10 for treatment, and then flows back to the reaction tank 4 for the next cycle of the electro-catalytic reactor 8-photo-reactor 10-reaction tank 4. The connecting path between the reaction tank 4 and the photo-reactor 10 is provided with a heat exchanger 12 and a temperature sensor 11 for detecting and controlling the temperature. The reaction tank 4 is also provided with a stirrer 5, a magnetic flap liquid level meter, a chloride ion detector 6 and an online COD detector; the chloride ion detector 6 and the online chemical oxygen demand (COD) detector are respectively used for monitoring the chloride ion concentration and the COD value of the wastewater in the reaction tank 4. The stirrer 5 includes an acid and alkali corrosion resistant stirring rod and a stirring motor installed on the top of the reaction tank 4, which is used to ensure that the wastewater can be uniformly mixed during the dosing process; the magnetic flap liquid level meter in the reaction tank 4 is interlocked with the circulating pump 7, which is used to ensure the minimum water level in the reaction tank 4, so as to avoid damage caused by the circulating pump 7 possibly sucking air due to the too low water level in the reaction tank 4.

[0040] The dosing barrel 13 is a polyethylene barrel, and the inside of the dosing barrel 13 is provided with a stirrer 15 and a dosing metering pump 14; the dosing metering pump 14 is used for accurately controlling the quantitative addition and stable conveying of the reagent; the dosing barrel 13 stores sodium chloride solution to ensure the chloride ion concentration requirement in the electro-catalytic process.

[0041] The electro-catalytic reactor 8 includes an electrolytic cell and an electrode 9 arranged in the electrolytic cell, the electrode 9 is connected with an external power supply, and the electrolytic cell is provided with water inlet and outlet. The electrode 9 is a pair of anode and cathode, wherein the anode is a ruthenium iridium titanium electrode plate, the cathode is a titanium electrode plate, the distance between the anode and the cathode is 10 mm, and the volume of the electro-catalytic reactor 8 is 2000 ml.

[0042] The photo-reactor 10 includes a flow channel and a ultraviolet light source arranged in the flow channel. The ultraviolet light source used in the embodiment is a mercury vapor lamp, which can provide ultraviolet light with a wavelength of 183 nm and 254 nm at the same time, and the irradiation intensity is 60 μW / cm²; the thickness of the flow channel is 25 mm, that is, the thickness of the water layer formed in the flow channel when the wastewater flows through is 25 mm; so that the wastewater can be fully irradiated by the ultraviolet light, so as to improve the utilization rate of the ultraviolet light, and then improve the efficiency of the organic matter in the wastewater treated by the photo- electro combined catalytic oxidation technology.

[0043] The specifications of the device for treating organic wastewater by photo-electric combined catalytic oxidation technology are divided according to the water treatment capacity, and different specifications of the device for treating organic wastewater by photo-electric combined catalytic oxidation technology can be constructed according to the required water treatment capacity. The specification of the device for treating organic wastewater by photo-electric combined catalytic oxidation technology constructed in the embodiment is 500 ml / h.

[0044] 2. Operation instruction of the device for treating organic wastewater by photo-electric combined catalytic oxidation technology The adjusting tank 1 collects and mixes the organic wastewater from the workshop, and when the wastewater stored in the adjusting tank 1 reaches a certain volume, the device for treating organic wastewater by photo-electric combined catalytic oxidation technology is started to treat the wastewater: The influent pump 3 transports wastewater from the equalization tank 1 to the reaction tank 4. The chloride ion detector 6 in the reaction tank 4 detects the chloride ion concentration in the wastewater. If the chloride ion concentration does not meet the set requirements, the sodium chloride solution in the dosing tank 13 is added to the reaction tank 4 via the dosing metering pump 14 until the chloride ion concentration in the reaction tank 4 reaches the set concentration. During the addition process, the agitator 5 in the reaction tank 4 is activated to ensure the accuracy of the chloride ion detector 6.

[0045] Once the chloride ion concentration in reaction tank 4 reaches the set concentration, the circulation pump 7 is started, and the electrocatalytic reactor 8 and photoreactor 10 are operated. The wastewater in reaction tank 4 is sequentially pumped into the electrocatalytic reactor 8 and photoreactor 10 via the circulation pump 7, where electrocatalytic reaction takes place in the electrocatalytic reactor 8 and photolysis reaction takes place in the photoreactor 10. The reaction process is exothermic. When the temperature sensor 11 detects that the water temperature at the outlet of the photoreactor 10 exceeds the set temperature, the heat exchanger 12 controls the reaction water temperature to a suitable reaction temperature (40-60℃).

[0046] Wastewater can be circulated multiple times in the cycle of reaction tank 4-electrocatalytic reactor 8-photoreactor 10-reaction tank 4. If the chloride ion detector 6 detects that the chloride ion concentration in reaction tank 4 does not meet the set requirements during the reaction process, the dosing metering pump 14 is started to add sodium chloride solution to reaction tank 4 to replenish the chloride ion concentration.

[0047] If the goal of wastewater treatment is to reduce COD to a certain value, then when the online chemical oxygen demand (COD) detector detects that the COD value of the wastewater in reaction tank 4 meets the standard, the circulating pump 7, electrocatalytic reactor 8 and photoreactor 10 stop operating, and then the drain valve of reaction tank 4 is opened, and the treated wastewater that meets the standard is discharged from the drain outlet of reaction tank 4.

[0048] 3. Experiment on the treatment of organic wastewater using photo-electro-catalytic oxidation technology The device for treating organic wastewater using the photo-electro-catalytic oxidation technology in this embodiment was used for treatment. The organic wastewater to be treated had a COD value of 1000 mg / L and a salinity of 15 g / L. The specific experimental steps are as follows: 3-1) The wastewater in equalization tank 1 is transferred to reaction tank 4, and the chloride ion concentration in the wastewater in reaction tank 4 is adjusted to 15g / L; 3-2) The wastewater in reaction tank 4 is transferred to electrocatalytic reactor 8, and an electrocatalytic reaction is carried out at 40°C for 2 minutes (single electrocatalytic reaction); the current density of the electrocatalytic reaction is 20 mA / cm². 2 The voltage is 60V; The wastewater in the electro-catalytic reactor 8 is transported into the flow channel of the photo-reactor 10 to form a water layer with a thickness of 25 mm, and the photolysis reaction is carried out under the action of ultraviolet light at a temperature of 40°C for 40s; 3-3) The wastewater treated by the photo-reactor 10 is transported into the reaction tank 4, and the steps 3-1), 3-2) and 3-3) are repeated until the wastewater in the reaction tank 4 reaches the standard and is discharged.

[0049] In this experiment, the COD value of the wastewater is set to be less than or equal to 100 mg / L as the standard value. After the device for treating organic wastewater by the photo-electric combined catalytic oxidation technology is operated for 120 min, the COD value of the wastewater is reduced to 100 mg / L, and the COD removal rate reaches 90%.

[0050] Example 2 The concentration of chloride ions is an important factor affecting the efficiency of wastewater treatment. This example studies the influence of different concentrations of chloride ions on the removal of organic matter: Preparation of wastewater: a mixed solution containing dimethyl sulfoxide and sodium chloride is used as wastewater, the COD value of the wastewater is 1000 mg / L, the salinity is 15 g / L, and the concentration of dimethyl sulfoxide is 50 mg / L; Using the "1, device for treating organic wastewater by photo-electric combined catalytic oxidation technology" in Example 1, and based on the "3, experiment of treating organic wastewater by photo-electric combined catalytic oxidation technology" in Example 1, only the following changes are made: ① In the corresponding step 3-1), the concentration of chloride ions is adjusted to 0, 2.5, 5, 10, 15 and 25 g / L, respectively, and wastewater treatment experiments are carried out; ② In the corresponding step 3-3), the treatment endpoint is set to be the concentration of dimethyl sulfoxide being 0; Every 30 min, samples are taken from the reaction tank 4, and the concentration of dimethyl sulfoxide in the wastewater is tested by high performance liquid chromatography.

[0051] The experimental results are shown in Figure 2 . Figure 2 The middle ordinate is the ratio of the concentration of dimethyl sulfoxide in the effluent (C t ) to the concentration of dimethyl sulfoxide in the initial wastewater (C0), and the lower the ratio represents the higher the removal rate of dimethyl sulfoxide in the wastewater; the abscissa is the treatment time, which is counted from the start of the circulating pump 7 and the start of the electro-catalytic reactor 8 and the photo-reactor 10.

[0052] Figure 2 The results show that when the concentration of Cl - in the wastewater in the reaction tank 4 is 0 g / L, the dimethyl sulfoxide is hardly degraded. When the concentration of Cl - begins to rise, as shown in Figure 2 , the concentration of Cl -At concentrations of 2.5, 5, and 10 g / L, the removal rate of dimethyl sulfoxide increased with the change in Cl... - The concentration increases with increasing Cl; this is because - The production of highly oxidizing substances such as sodium hypochlorite and active chlorine (•Cl) under the synergistic effect of light and electricity is specifically due to the following reasons: When Cl in wastewater - At a concentration of 0 g / L, sodium hypochlorite and Cl cannot be generated in the wastewater. It only has a small amount of hydroxyl radicals (•OH) generated by water electrolysis, which have almost no degradation effect on dimethyl sulfoxide. When Cl in wastewater - As the concentration gradually increases, the conductivity of the wastewater increases, thus increasing the rate of electrocatalytic production of •OH. On the other hand, the concentration of Cl... - The amount of hypochlorous acid and Cl produced also increases, which intensifies the degradation of dimethyl sulfoxide; However, with Cl - When the concentration increases to 15 g / L or higher, the removal rate of dimethyl sulfoxide decreases, indicating that Cl... - Excessive concentrations can inhibit the degradation of dimethyl sulfoxide (DMSO), due to the high concentration of Cl... - It has a quenching effect on •OH, thereby reducing the degradation rate of dimethyl sulfoxide; Cl - The inhibitory effect was more pronounced at a concentration of 25 g / L compared to 15 g / L.

[0053] In summary, within a certain range, as the Cl in the wastewater... - As the concentration increases, the removal rate of organic matter also increases, but when the Cl concentration in the wastewater increases... - When the concentration exceeds this range, the removal rate of organic matter actually increases with Cl. - The concentration of Cl in the wastewater decreases with increasing concentration. This experimental result shows that, under otherwise constant conditions, the concentration of Cl in the wastewater... - The degradation effect of dimethyl sulfoxide is relatively ideal when the concentration is 10~15g / L.

[0054] Example 3 The different current densities of the electrocatalytic reaction carried out in electrocatalytic reactor 8 also affect the removal efficiency of organic matter in wastewater. This embodiment studies the effect of different current densities on the removal efficiency of organic matter in wastewater: Wastewater preparation: A mixture containing dimethyl sulfoxide and sodium chloride is used as wastewater, wherein the wastewater has a COD value of 1000 mg / L, a salinity of 10 g / L, and a dimethyl sulfoxide concentration of 50 mg / L; Using "1. Apparatus for treating organic wastewater using photo-electro-catalytic oxidation technology" in Example 1, the only difference from "3. Experiment on treating organic wastewater using photo-electro-catalytic oxidation technology" in Example 1 is as follows: ①The current density of the electrocatalytic reaction corresponding to step 3-2) is 5, 10, 15, 20, 25, 30 mA / cm 2 , respectively, and wastewater treatment experiments are carried out.

[0055] ②The treatment endpoint in step 3-3) is set as the concentration of dimethyl sulfoxide being 0; Every 30 minutes, samples are taken from the reaction tank 4, and the concentration of dimethyl sulfoxide in the wastewater is tested by high performance liquid chromatography.

[0056] The experimental results are shown in Figure 3 : Figure 3 The ordinate is the ratio of the concentration of dimethyl sulfoxide in the effluent (C t ) to the concentration of dimethyl sulfoxide in the initial wastewater (C0), and the lower the ratio, the higher the removal rate of dimethyl sulfoxide in the wastewater; the abscissa is the treatment time, which is counted from the start of the circulating pump 7 and the start of the electrocatalytic reactor 8 and the light reactor 10.

[0057] Figure 3 The results show that as the current density of the electrocatalytic reaction increases from 5 mA / cm 2 to 30 mA / cm 2 , the removal rate of dimethyl sulfoxide increases significantly. When the current density is 20 mA / cm 2 , 25 mA / cm 2 and 30 mA / cm 2 , respectively, and the treatment time is 90 min, the removal rate of dimethyl sulfoxide in the high-salt wastewater is as high as 84%, 90% and 92%, respectively; and when the treatment time is continuously extended to 120 min, dimethyl sulfoxide in the high-salt wastewater is completely removed.

[0058] When the current density is 5 mA / cm 2 , 10 mA / cm 2 and 15 mA / cm 2 , respectively, and the treatment time is 90 min, the removal rate of dimethyl sulfoxide in the high-salt wastewater is all below 40%, and when the treatment time is continuously extended to 180 min, the removal rate of dimethyl sulfoxide in the high-salt wastewater is 38%, 37% and 62%, respectively, and the treatment effect is poor.

[0059] Therefore, a current density of 20 mA / cm 2 or above is required to achieve a higher removal effect of organic matter. Figure 3 The current density is 20 mA / cm 2 , 25 mA / cm 2 and 30 mA / cm 2At this time, the removal efficiency of dimethyl sulfoxide at each time point is relatively close, and the curve coincidence degree is high. Considering energy saving and cost reduction, the current density is preferably 20-25 mA / cm 2 .

[0060] Example 4 The researchers found that light-electric combined catalytic oxidation was needed to achieve good high-salinity wastewater organic matter removal efficiency, and single photolysis reaction or single electrocatalytic reaction could not achieve the purpose of the application, which is verified as follows: Preparation of wastewater: a mixed solution containing dimethyl sulfoxide and sodium chloride is used as wastewater, the COD value of the wastewater is 1000 mg / L, the salinity is 10 g / L, and the concentration of dimethyl sulfoxide is 50 mg / L; Experimental method: The "1, device for treating organic wastewater by light-electric combined catalytic oxidation technology" in Example 1 is used to set up three groups of experiments, which are: (1) Single photolysis reaction (UV): the electrocatalytic reactor 8 is not started, and only the light reactor 10 is turned on; (2) Single electrocatalytic reaction (electrocatalysis): the light reactor 10 is not started, and only the electrocatalytic reactor 8 is turned on; (3) Light-electric combined catalysis (photoelectrocatalysis): both the electrocatalytic reactor 8 and the light reactor 10 are turned on, and the control conditions of the electrocatalytic reactor 8 are the same as in (2); the control conditions of the light reactor 10 are the same as in (1).

[0061] Other parameters to be set are the same as in "3, experiment of treating organic wastewater by light-electric combined catalytic oxidation technology" in Example 1.

[0062] In the experiment, samples are taken from the reaction tank 4 every 30 minutes, and the concentration of dimethyl sulfoxide in the wastewater is tested by high performance liquid chromatography.

[0063] Figure 4 The vertical coordinate is the ratio of the concentration of dimethyl sulfoxide in the effluent (C t ) to the concentration of dimethyl sulfoxide in the initial wastewater (C0), and the lower the ratio, the higher the removal rate of dimethyl sulfoxide in the wastewater; the horizontal coordinate is the treatment time, which is counted from the start of the circulating pump 7 and the start of the electrocatalytic reactor 8 and the light reactor 10.

[0064] Figure 4 The results show that single photolysis reaction (corresponding to UV in Figure 4 ) cannot remove dimethyl sulfoxide in the wastewater; single electrocatalytic reaction (corresponding to electrocatalysis in Figure 4The removal effect of dimethyl sulfoxide in the wastewater by the electro-catalysis is slightly higher than that by the single photolysis, but the removal rate is still limited, and the removal rate of dimethyl sulfoxide is only 10% after 180 min of treatment; while the removal rate of dimethyl sulfoxide by the photo-electric combined catalysis (corresponding to the photo-electric combined catalytic oxidation technology for treating the organic wastewater) is 100%. Figure 4 The removal rate of the organic matter in the wastewater by the photo-electric combined catalysis is significantly improved, and the removal rate is close to 100% after 180 min.

[0065] This shows that the photolysis reaction by using the photoreactor 10 alone and the electro-catalysis reaction by using the electro-catalysis reactor 8 alone cannot achieve the ideal effect for treating the organic matter in the wastewater, and the photo-electric combined catalytic oxidation technology is required to achieve a better effect for removing the organic matter in the wastewater, because the photolysis reaction and the electro-catalysis reaction have a significant synergistic effect on degrading the organic matter, which greatly improves the degradation efficiency, and also verifies the feasibility and superiority of the photo-electric combined catalytic oxidation technology.

[0066] Example 5 This embodiment constructs a device with the same structure as the device for treating the organic wastewater by the photo-electric combined catalytic oxidation technology in Example 1, but the size of the device is enlarged, and the specification is 20 t / d (the daily wastewater treatment capacity is 20 tons), and the distance between the anode and the cathode is 20 mm, and the volume of the electro-catalysis reactor 8 is 200 L.

[0067] The device is used to run under the actual working condition to perform the wastewater treatment experiment, and specifically: The wastewater source is the high-salt wastewater containing a large amount of dimethyl sulfoxide generated in the production process of a pharmaceutical factory in Nanjing, wherein the COD value is 1600 mg / L, the ammonia nitrogen concentration is 11.56 mg / L, the total nitrogen is 70.25 mg / L, the chloride ion concentration is 12 g / L, and the salinity is 20 g / L.

[0068] The device for treating the organic wastewater by the photo-electric combined catalytic oxidation technology with the specification of 20 t / d is started to treat the wastewater, and specifically includes the following steps: S1: The wastewater in the adjusting tank 1 is transported to the reaction tank 4, and the chloride ion concentration of the wastewater in the reaction tank 4 is adjusted to 10 g / L; if it is lower than 10 g / L, the sodium chloride solution is added. Since the initial chloride ion concentration of the wastewater in this embodiment is 12 g / L, the sodium chloride solution does not need to be added for the first time; S2: The wastewater in the reaction tank 4 is transported to the electro-catalysis reactor 8, and the electro-catalysis reaction is performed at a temperature of 40°C for 2 min (single electro-catalysis reaction); the current density of the electro-catalysis reaction is 20 mA / cm 2 , and the voltage is 60 V; The wastewater in the electro-catalysis reactor 8 is transported to the flow channel of the photoreactor 10 to form a water layer with a thickness of 25 mm, and the photolysis reaction is performed under the action of the ultraviolet light at a temperature of 40°C for 40 s. S3: deliver the wastewater treated by the photoreactor 10 into the reaction tank 4, and repeat the step S1, the step S2 and the step S3 until the wastewater in the reaction tank 4 reaches the standard, and then discharge.

[0069] To verify the wastewater treatment effect, the COD value, the ammonia nitrogen concentration, the total nitrogen concentration and the dimethyl sulfoxide concentration in the wastewater are all set as 0 as the standard value.

[0070] During the experiment, the wastewater in the reaction tank 4 is sampled every 0.5 hour, and the COD value, the ammonia nitrogen concentration, the total nitrogen concentration and the dimethyl sulfoxide concentration in the treated wastewater are detected, and the results are shown in Table 1, Figure 5 Table 1: treatment results of high-salinity wastewater containing dimethyl sulfoxide

[0071] The results in Table 1 show that the device for treating organic wastewater by using the photo-electric combined catalytic oxidation technology provided by the application and the method for treating organic wastewater by using the photo-electric combined catalytic oxidation technology provided by the application can effectively remove the organic matter in the high-salinity wastewater in the actual working condition, and also has a good removal rate for the pollutants such as ammonia nitrogen and total nitrogen which depend on oxidation decomposition.

[0072] Figure 5 The liquid chromatogram for detecting dimethyl sulfoxide in the wastewater treatment process is shown in the figure, wherein the peak time corresponding to dimethyl sulfoxide is 3.7 min.

[0073] It can be known from the analysis of the chromatogram that in the actual wastewater treatment process, the peak area corresponding to the dimethyl sulfoxide peak in the wastewater gradually decreases with the increase of the reaction time, and the peak area of the small molecule substance peak with a peak time of about 3 min increases, which indicates that the content of dimethyl sulfoxide in the wastewater decreases with the increase of the reaction time, and the dimethyl sulfoxide is degraded into other small molecule substances. After 1.5 h of reaction, the dimethyl sulfoxide in the wastewater is almost completely decomposed, and no irritating odor is generated in the whole treatment process.

[0074] The above description is a schematic description of the application and its embodiments, which is not restrictive, and the embodiments shown in the examples are only one of the embodiments of the application, and the actual embodiments are not limited thereto. Therefore, if a person skilled in the art is inspired thereby, without departing from the purpose of the application, similar embodiments and examples of the technical solutions can be designed without creativity, which should all belong to the protection scope of the application.​

Claims

1. The device for treating organic wastewater by photo-electric combined catalytic oxidation technology, characterized in that, The device comprises: a reaction tank (4), a circulating pump (7), an electro-catalytic reactor (8) and a photo-reactor (10) connected in sequence, and the reaction tank (4) and the photo-reactor (10) form a liquid flow circuit; the electro-catalytic reactor (8) comprises an electrolytic cell and an electrode (9) arranged in the electrolytic cell; the photo-reactor (10) comprises a flow channel and a UV light source arranged in the flow channel; wherein, the wavelength of the UV light source comprises 180-185 nm and 250-260 nm; the irradiation intensity of the UV light source is 10-80 μW / cm²; the thickness of the flow channel is 10-30 mm.

2. The apparatus for treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 1, characterized in that, a dosing tank (13) is further included, which is in communication with the reaction tank (4) and used for adding a chlorine ion-containing liquid medicine into the reaction tank (4).

3. The apparatus for treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 1 or 2, characterized in that, the anode material of the electrode (9) comprises one or more of ruthenium iridium titanium, graphite and diamond; the cathode material of the electrode (9) comprises one or more of titanium, stainless steel and graphite; the distance between the anode and the cathode is 5-20 mm.

4. The apparatus for treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 3, characterized in that, The device for treating organic wastewater by the photo-electric combined catalytic oxidation technology further comprises a regulating tank (1). The regulating tank (1) is in communication with the reaction tank (4) through a water inlet pump (3).

5. The apparatus for the treatment of organic wastewater by photo-electric combined catalytic oxidation technology according to claim 4, characterized in that, The reaction tank (4) is provided with a stirrer (5), a chlorine ion detector (6) and a magnetic float liquid level meter. A heat exchanger (12) and a temperature sensor (11) are arranged on the connecting passage between the reaction tank (4) and the photo-reactor (10).

6. A method for treating organic wastewater by photo-electric combined catalytic oxidation technology, characterized in that, The method comprises the following steps: S1: adjusting the chlorine ion concentration of the wastewater in the reaction tank (4) to 10-15 g / L; S2: conveying the wastewater in the reaction tank (4) to the electro-catalytic reactor (8) to perform electro-catalytic reaction at a temperature of 40-60 ℃ for 1-3 min; conveying the wastewater in the electro-catalytic reactor (8) to the flow channel of the photo-reactor (10) to form a water layer with a thickness of 10-30 mm, and performing photolysis reaction under the action of UV light at a temperature of 40-60 ℃ for 30-60 s; S3: conveying the wastewater treated by the photo-reactor (10) to the reaction tank (4) to repeat the steps S1, S2 and S3 until the wastewater in the reaction tank (4) reaches the standard and is discharged.

7. The method of treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 6, characterized in that, In step S1, the chlorine ion-containing liquid medicine is added into the reaction tank (4) by the dosing tank (13) to adjust the chlorine ion concentration of the wastewater in the reaction tank (4); the chlorine ion-containing liquid medicine comprises one or more of sodium chloride, potassium chloride and calcium chloride solution.

8. The method for treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 7, characterized in that, The anode material of the electro-catalytic reaction comprises one or more of ruthenium iridium titanium, graphite and diamond, and the cathode material comprises one or more of titanium, stainless steel and graphite; the distance between the anode and the cathode is 5-20 mm.

9. The method of treating organic wastewater by photo-electric combined catalytic oxidation technology according to claim 8, characterized in that, The electrocatalytic reaction includes: current density is 20~25mA / cm 2 ; voltage is 10~60 V.

10. The method for treating organic wastewater by photo-electric combined catalytic oxidation technology according to any one of claims 7-9, characterized in that, The photolysis reaction satisfies one or more of the following (i)-(iii) conditions: (i) the wavelength of the UV light comprises 180-185 nm and 250-260 nm; (ii) the irradiation intensity of the UV light is 10-80 μW / cm²; (iii) the thickness of the water layer under the action of the UV light is 10-30 mm.

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