Electrochemical ozone oxidation coupling wastewater treatment device and wastewater treatment method

Abstract

This invention relates to the field of fine chemical wastewater treatment technology, and discloses an electrochemical ozone oxidation coupling wastewater treatment device and method. The device includes a particle electrode bed and an anode and cathode disposed on the particle electrode bed. The anode is a rod-shaped anode and / or a tubular anode, and the cathode is a tubular cathode with aeration function. The anode and cathode are arranged perpendicular to the bottom of the particle electrode bed. Compared with traditional three-dimensional electrode systems, the device provided by this invention has more ·OH generation pathways, enabling more efficient wastewater treatment. Furthermore, by optimizing the electrode material, shape, and assembly method, the effluent quality can be further improved. In addition, the device provided by this invention has the advantages of not generating secondary pollution and requiring no additional reagents during use, making it easier to manage and promote its application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fine chemical wastewater treatment, and particularly relates to an electrochemical ozone oxidation coupling wastewater treatment device and a wastewater treatment method. BACKGROUND

[0002] Typical industries of fine chemicals, such as dyes, medicines, pesticides and the like, produce organic wastewater with high organic matter concentration, poor biodegradability, high salt content and poor biodegradability in the production process. It is difficult to meet the standard by using conventional biochemical treatment methods. The ammonia nitrogen in fine chemical wastewater is mainly due to the use of ammonia water as raw material, precipitant or detergent and the like in the production process of some fine chemical products and the conversion of aniline and other nitrogen-containing organic matter. High-concentration ammonia nitrogen, especially free ammonia, can have a toxic effect on the biological system.

[0003] Advanced oxidation technology is to produce a strong oxidizing agent ·OH to oxidize organic matter without selectivity, and even to completely mineralize organic matter. Three-dimensional electrode electrocatalytic oxidation technology is to fill particle electrodes between the cathode and the anode to form a three-dimensional electrode to increase the reaction area of the electrode, which greatly improves the treatment efficiency of wastewater compared with the traditional electrocatalytic oxidation system.

[0004] The principle of ·OH generated by the electrochemical system is: direct electron transfer to the anode surface (M), the intermediate product produced in the process of water oxidation into oxygen, including HO· strongly physically adsorbed on the anode surface, represented as M(HO·), and weaker oxidants such as H2O2 generated by the dimerization reaction of M(HO·). At the same time, when the electrochemical system treats wastewater containing ammonia nitrogen, it is necessary to contain chloride ions in the water. The principle is that the anode oxidizes chloride ions to produce active chlorine, which removes ammonia nitrogen by breakpoint chlorination.

[0005] MO+H2O→M(HO·)+H + +e -

[0006] 2M(HO·)→2MO+H2O2

[0007] However, the way of generating ·OH in this way is limited, and the treatment effect is often not ideal. Moreover, the system relies on chloride ions for ammonia nitrogen removal, and some wastewater needs to contain a certain amount of chloride ions or additional chlorine gas or the addition of sodium chloride and other reagents, which not only increases the treatment cost, but also may cause secondary pollution and other problems. SUMMARY

[0008] The present application aims to overcome the problems of the prior art, such as limited ways of generating ·OH in the wastewater treatment system using a three-dimensional electrode catalytic oxidation reactor, unsatisfactory treatment effect, and the need for additional chloride ions, and provides an electrochemical ozone oxidation coupled wastewater treatment device and a wastewater treatment method. The device provides multiple ways of generating ·OH through the coupling of electrochemical systems and ozone catalytic oxidation, and can achieve efficient oxidation treatment of organic matter in wastewater without the need for additional reagents.

[0009] To achieve the above-mentioned purpose, in one aspect, the present application provides a wastewater treatment device, which comprises a particle electrode bed layer, and an anode and a cathode arranged on the particle electrode bed layer, wherein the anode is a rod-shaped anode and / or a tubular anode, the cathode is a tubular cathode with aeration function, and the anode and the cathode are arranged vertically to the bottom of the particle electrode bed layer.

[0010] In a second aspect, the present application provides a wastewater treatment method, which comprises passing wastewater into the device as described in the first aspect above, and oxidizing organic matter in the wastewater by electrochemical and ozone oxidation coupling, so as to remove the organic matter in the wastewater.

[0011] Through the above technical solution, the present application can achieve the following beneficial effects:

[0012] (1) The device provided by the present application can realize multi-path oxidation of organic matter in wastewater. By alternately arranging rod-shaped anodes and tubular cathodes with aeration function, multiple small electrochemical systems are formed in the device. Compared with traditional treatment devices using plate-shaped electrodes, the water quality of the effluent can be effectively improved, and the area of the electrodes is increased, and the treatment time of the wastewater is reduced.

[0013] (2) The device provided by the present application does not produce secondary pollution, and does not need to add other reagents during use. Not only does it reduce the cost of reagents in the wastewater treatment process, but it also simplifies the operation steps in the treatment process, reduces the cost and secondary pollution problems caused by the introduction of reagents, and is more conducive to management and application. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is a schematic diagram of the device for ozone coupling electrocatalytic oxidation treatment of fine chemical wastewater used in the examples.

[0015] Figure 2 (a)-(g) are schematic diagrams of different electrode arrangements used in the examples, which mainly show the positional relationship between different electrodes in the wastewater treatment device, and the relative distance relationship between adjacent electrodes and between the electrodes and the side wall of the particle electrode bed layer, but do not show the proportional relationship between the diameter of the electrodes and the distance between adjacent electrodes, and the proportional relationship between the cross-sectional area of the electrodes and the bottom area of the particle electrode bed layer.

[0016] BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Figure 1 shows the schematic diagram of the wastewater treatment device of the present application, wherein 1 - water inlet tank; 2 - water inlet pump; 3 - water inlet flow meter; 4 - particle electrode B; 5 - particle electrode A; 6 - gas flow meter; 7 - ozone generator; 8 - anode; 9 - tubular cathode; 10 - direct current power supply; 11 - water outlet tank; 12 - oxygen source; 13 - tail gas destroyer.

[0018] Figure 2 Figure 2 shows the schematic diagram of the wastewater treatment device of the present application, wherein + represents tubular anode; - represents tubular cathode. DETAILED DESCRIPTION

[0019] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not critical to the present application. Any numerical value, however, can be expressed as a range to include any and all subranges therebetween. The ranges and / or numerical values recited herein are approximations. Although the exact dimensions need not be used in the application, the desired properties will be obtained by being within about 10% of the value recited.

[0020] In the present application, the specific shape of the electrodes used as anode and cathode in the provided device is not particularly limited, as long as it meets the following features in the present application. That is, the rod / tubular electrode used in the present application can meet the basic features of "rod" or "tube", and the specific shape of its cross section is not particularly limited. For example, its cross section can be circular, oval, square, triangular or other polygonal, etc. For the convenience of description, the following is described according to the electrode cross section being circular. When a rod / tubular electrode with other cross section shape is used, it can be regarded as a rod / tubular electrode with the cross section center as the center of the circle and the longest distance from the cross section center to the edge of the cross section as the radius, and the assembly of the wastewater treatment device is carried out according to the following features.

[0021] In the present application, the cross-sectional area of the rod electrode is the base area unless otherwise specified; the cross-sectional area of the tubular electrode is the base area calculated according to the size of its outer diameter profile.

[0022] In the present application, the height-diameter ratio of the rod electrode is the ratio of its height to the diameter of the base unless otherwise specified. The height-diameter ratio of the tubular electrode is the ratio of its height to the inner diameter of the base.

[0023] In the present application, the diameter of the electrode refers to the diameter of the rod electrode or the outer diameter of the tubular electrode unless otherwise specified.

[0024] The inventor of the present application found that the effective area of the electrode plate in the conventional three-dimensional electrode device is small, and the treatment efficiency of the organic matter in the wastewater is low. After a large amount of research, the inventor ingeniously found that the electrode is made into a rod or a tube, and is vertically arranged in the particle electrode bed (that is, the high direction of the rod / tube electrode is perpendicular to the bottom of the particle electrode bed), which not only effectively increases the electrode area, but also, on this basis, the cathode and the anode are arranged alternately, which can form multiple small electrochemical systems in the device, thereby effectively improving the treatment efficiency and the quality of the effluent. After further research, the inventor also found that by arranging the electrode of the cathode into a tube with an air inlet and an air outlet, and connecting it with an ozone supply device, the electrode used in the cathode can simultaneously function as an electrode and an aeration device, which can control the aeration mode (such as uniform aeration or concentrated aeration) through the arrangement of the tubular electrode, and also promotes the rapid and effective contact between ozone and hydrogen peroxide, the electrolysis product of the electrode, thereby providing more ·OH sources for the device, and improving the wastewater treatment efficiency and effect.

[0025] Based on the above findings, the present application provides a wastewater treatment device, which comprises a particle electrode bed and an anode and a cathode arranged on the particle electrode bed, wherein the anode is a rod-shaped anode and / or a tubular anode, the cathode is a tubular cathode with aeration function (for example, an aeration port is arranged on the tubular cathode, preferably below 1 / 4 of the bottom of the tubular cathode), and the anode and the cathode are arranged vertically to the bottom of the particle electrode bed.

[0026] According to a preferred embodiment of the present application, the anode and the cathode are uniformly arranged on the particle electrode bed in an alternating arrangement. The alternating arrangement means that at least one of the adjacent electrodes around each anode is a cathode, and preferably the electrodes adjacent to each anode in the front, back, left and right directions are all cathodes, and vice versa. Uniform means that the electrodes are evenly dispersed according to the bottom area of the particle electrode bed and the number of anodes and cathodes.

[0027] According to a preferred embodiment of the present application, the particle electrode bed is filled with particle electrodes with conductivity and catalytic activity.

[0028] Any particle electrode with the aforementioned features can be used in the device provided by the present application. According to a preferred embodiment of the present application, the particle electrode is selected from particle electrode A and / or particle electrode B, wherein the particle electrode A is a carbon fiber material loaded with polytetrafluoroethylene, and the particle electrode B is a catalyst with γ-Al2O3 as the carrier and transition metal as the active component.

[0029] In the present application, the packing mode of the particle electrode in the bed is not particularly limited. In order to improve the gas dispersion effect, strengthen the oxygen reduction in the cathode, accelerate the decomposition of ozone, and generate more ·OH, preferably, the particle electrode bed is layered with particle electrode A (which can improve the gas dispersion effect) and particle electrode B (which can catalyze the accelerated decomposition of ozone), wherein particle electrode A is packed in the lower layer and particle electrode B is packed in the upper layer, and the packing amount of the particle electrode is preferably such that the thickness ratio of the particle electrode A packing layer to the particle electrode B packing layer is 1:1-2.

[0030] According to a preferred embodiment of the present application, the loading amount of polytetrafluoroethylene in the particle electrode A is 0.1-3% by weight based on the total weight of the particle electrode A. Preferably, it is 0.5-2% by weight.

[0031] In the present application, the source of the particle electrode A used is not particularly limited, and it can be a commercially available or customized product with the above characteristics, or a related product with the above characteristics prepared according to the prior art.

[0032] According to a preferred embodiment of the present application, the preparation method of the particle electrode A comprises:

[0033] (1) Soak the clean carbon fiber material in a polytetrafluoroethylene dispersion liquid for 1-5h, preferably the content of polytetrafluoroethylene in the polytetrafluoroethylene dispersion liquid is 5-10% by weight;

[0034] (2) Place the soaking product in a muffle furnace, heat it to 400-450℃ at a rate of 1-10℃ / min, and keep it at this temperature for 50-100min.

[0035] In the present application, the source of the "clean carbon fiber material" in the above method is not particularly limited. It can be a product obtained directly by commercial or customized means, or a related product obtained by cleaning the carbon fiber material according to the prior art.

[0036] Preferably, the above method can further comprise a step of cleaning the carbon fiber material before step (1) to remove impurities on the material, thereby obtaining a clean carbon fiber material. Preferably, the impurities on the material are removed by soaking the carbon fiber material in an organic solvent aqueous solution with a concentration of 15-25% by volume at 20-30℃ for 10-20min of ultrasonic treatment. Preferably, the organic solution can be selected from at least one of methanol, ethanol, acetone and other water-soluble organic solvents.

[0037] In order to achieve better cleaning effect and facilitate subsequent loading of polytetrafluoroethylene, according to a preferred embodiment of the present application, the cleaning step comprises sequentially subjecting the carbon fiber material to ultrasonic treatment in 15-25% (by volume) methanol aqueous solution, 15-25% (by volume) ethanol aqueous solution and 15-25% (by volume) acetone aqueous solution at 20-30°C, respectively, for 10-20 min each time.

[0038] Preferably, the average density of the carbon fiber material is 1.5-2 g / cm 3 , the carbon content is not less than 95% by weight, and the monofilament diameter is 5-10 μm.

[0039] In the present application, the source of the polytetrafluoroethylene dispersion used is not particularly limited. For example, it can be a commercially available product, or a commercially available product (such as a commercially available concentrated polytetrafluoroethylene dispersion) can be used after adjusting its concentration (such as dilution with deionized water).

[0040] According to a preferred embodiment of the present application, in the particle electrode B, the loading amount of the transition metal is not less than 0.2% by weight based on the total weight of the catalyst. Preferably, it is 0.2-2% by weight. More preferably, it is 0.2-1% by weight. The loading amount of the transition metal refers to its total loading amount. When only one kind of transition metal is loaded, the loading amount is the percentage of the transition metal in the total weight of the catalyst. When multiple transition metals are loaded, the loading amount is the sum of the percentages of these transition metals in the total weight of the catalyst. Preferably, the transition metal is selected from at least one of Mn, Cu, Ce and Co.

[0041] Preferably, the particle electrode B has a particle size of 3-6 mm. The present application does not particularly limit the specific shape of the particle electrode B, which can be any commonly used catalyst shape in the art. When the particle electrode B is a spherical particle, the particle size is its diameter. When the particle electrode B is a particle of other shape, the particle size is its equivalent diameter. The equivalent diameter refers to the diameter of a non-spherical particle converted into a spherical shape by a certain specific method. In the production process, in order to facilitate operation, a sieve screening method can be used to obtain the required non-spherical particle electrode B. For example, a sieve with a mesh size of 3 mm and 6 mm can be used for screening. The particle electrode B that can pass through the 6 mm sieve but cannot pass through the 3 mm sieve has a particle size of 3-6 mm.

[0042] The inventors of the present application have also found in research that when the rod / tube electrode surface used in the device provided by the present application has a porous structure, on the one hand, the electrode area is further increased, and on the other hand, the pollutants can be adsorbed on the electrode surface, thereby more effectively contacting the ·OH generated by the electrode, thereby improving the treatment efficiency and treatment effect of the pollutants (especially organic matter and ammonia nitrogen, etc.).

[0043] In the present application, the specific material of the anode is not particularly limited. According to a preferred embodiment of the present application, the anode is a Ti / PbO2 electrode. Preferably, the anode is a Ti / PbO2 electrode made of Ti supporting porous PbO2, and preferably the average pore size of the porous PbO2 is 1-10 μm.

[0044] In the present application, the source of the Ti / PbO2 electrode is not particularly limited. It can be a commercially available or custom-made product having the above-mentioned characteristics, or a product having the above-mentioned characteristics prepared according to the prior art.

[0045] According to a preferred embodiment of the present application, the preparation method of the Ti / PbO2 electrode comprises: immersing (tubular and / or rod-shaped) Ti electrode in aqueous oxalic acid solution (etching), and then using a mixed aqueous solution of Pb(NO3)2 and nitric acid as an electroplating solution to perform electrodeposition, so that PbO2 is electrodeposited on the oxalic acid-etched Ti electrode to obtain a Ti / PbO2 electrode. In this process, hydrogen bubbles are generated on the surface of the electrode, and the hydrogen adsorbed on the electrode causes PbO2 to precipitate in the interstices between the bubbles to form a porous structure.

[0046] Preferably, the content of oxalic acid in the aqueous oxalic acid solution is 5-15% by weight.

[0047] Preferably, the conditions for immersion include a temperature of 50-70°C and a time of 5-15 min.

[0048] Preferably, the electroplating solution is a mixed solution of 0.2-0.3 M Pb(NO3)2 and 0.05-0.15 M HNO3.

[0049] Preferably, the conditions for electrodeposition include a temperature of 10-30°C, a time of 5-15 min, and a current density of 15-25 mA / cm2. 2 Preferably, the electrodeposition process is carried out under constant current conditions (the difference between the maximum current and the minimum current during the process is not more than 2 mA).

[0050] The inventors of the present application have further found that by adjusting the size and distribution mode and density of the anode and the cathode, the treatment efficiency and effect of organic matter and ammonia nitrogen in wastewater can be further improved. Based on this, preferably, the cross-sectional area of the (single) anode is 0.5-8% of the total bottom area of the particle electrode bed. Preferably, it is 0.5-5%. For example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any intermediate value between any two of the above values.

[0051] More preferably, the high-diameter ratio of the anode is 10-50.

[0052] Preferably, the number of the anodes is set to 8-128 relative to 1 m 2 of the bottom surface of the particle electrode bed layer.

[0053] More preferably, the height of the rod-shaped anode covered by the particle electrode filled in the particle electrode bed layer is 25%-50% of the height of the rod-shaped anode.

[0054] According to a preferred embodiment of the present application, the cathode comprises a metal electrode and polytetrafluoroethylene loaded on the metal electrode.

[0055] Preferably, the polytetrafluoroethylene accounts for 0.1-1% by weight of the total weight of the cathode.

[0056] Preferably, the tubular metal electrode is a Ti or Ti / PbO2 electrode. Preferably, the Ti / PbO2 electrode is a Ti electrode loaded with porous PbO2. The preparation method is as described above and will not be repeated here.

[0057] In the present application, the source of the cathode used in the provided device is not particularly limited as long as its features meet the aforementioned requirements. It can be a commercially available or customized product with the above-mentioned features, or a related product prepared according to the prior art.

[0058] According to a preferred embodiment of the present application, the preparation method of the cathode comprises:

[0059] (1) soaking a clean (tubular) metal electrode in a polytetrafluoroethylene dispersion liquid for 1-5 h. Preferably, the content of polytetrafluoroethylene in the polytetrafluoroethylene dispersion liquid is 10-20% by weight;

[0060] (2) placing the soaking product in a muffle furnace, heating it to 500-600℃ at a rate of 1-10℃ / min, and keeping it at this temperature for 60-360 min.

[0061] In the present application, the source of the "clean" metal electrode in the above-mentioned method is not particularly limited. It can be a product directly obtained by commercialization or customization, or a related product obtained by cleaning a metal electrode with the aforementioned features according to the prior art.

[0062] Preferably, the method further comprises a step of cleaning the metal electrode before step (1) to remove impurities on the surface of the metal electrode, thereby obtaining a clean metal electrode. Preferably, the impurities on the surface of the metal electrode are removed by immersing the metal electrode in an organic solvent aqueous solution with a concentration of 15-25% by volume, and ultrasonic treatment at 20-30°C for 10-20 min. Preferably, the organic solvent can be at least one selected from the group consisting of methanol, ethanol, acetone and other water-soluble organic solvents.

[0063] In order to achieve better cleaning effect and facilitate subsequent loading of polytetrafluoroethylene, according to a preferred embodiment of the present application, the cleaning step comprises sequentially immersing the metal electrode in 15-25% by volume methanol aqueous solution, 15-25% by volume ethanol aqueous solution and 15-25% by volume acetone aqueous solution, and ultrasonic treatment at 20-30°C for 10-20 min each time.

[0064] According to a preferred embodiment of the present application, the cross-sectional area of the tubular cathode is 0.5-8% of the total bottom area of the particle electrode bed. Preferably, it is 0.5-5%. For example, it can be 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any intermediate value between any two of the above values.

[0065] More preferably, the tubular cathode has a height-diameter ratio of 10-50, and a ratio of outer diameter to inner diameter of 1.1-1.2.

[0066] More preferably, the tubular cathode is covered by the particle electrodes packed in the particle electrode bed to a height of 25-50% of the height of the tubular cathode.

[0067] Preferably, the number of tubular cathodes is 8-128 with respect to the bottom surface of the particle electrode bed of 1 m 2 .

[0068] According to a preferred embodiment of the present application, the number ratio of the rod-shaped anodes to the tubular cathodes in the device is 1:0.5-1.5. Preferably, it is 1:0.8-1.2.

[0069] According to a preferred embodiment of the present application, the distance between the anode and its adjacent cathode is 0.6-5 times the diameter of the anode.

[0070] According to a preferred embodiment of the present application, the device further comprises a direct current power supply, an ozone generator and a tail gas destroyer.

[0071] In the present application, the direct current power supply serves to power the three-dimensional electrode system. Preferably, the direct current power supply is connected to the anode and the cathode as described above, respectively.

[0072] In the present application, the ozone generator is used to provide the device with ozone source, so as to realize the coupling of ozone oxidation and three-dimensional electrode oxidation, and improve the treatment efficiency and effect of the wastewater. Preferably, the ozone generator is connected with the gas inlet at the top of the tubular cathode, so that the ozone is introduced into the device through the tubular cathode.

[0073] More preferably, the ozone generator comprises an oxygen source and an ozone generating device, and the oxygen generated by the oxygen source is converted into ozone by the ozone generating device. The generated ozone is introduced into the wastewater treatment device provided by the present application through the pipeline connected between the ozone generator and the tubular cathode.

[0074] In the present application, the tail gas destroyer is used to treat the gas (such as unoxidized ozone) generated in the wastewater treatment process, so as to avoid secondary pollution to the environment. Preferably, the tail gas destroyer is connected with the exhaust port of the device to remove the residual ozone in the tail gas.

[0075] More preferably, the device further comprises a tail gas collection device connected with the tail gas destroyer, so as to introduce the tail gas generated in the wastewater treatment process into the tail gas destroyer for treatment.

[0076] According to a particularly preferred embodiment of the present application, wherein, with reference to Figure 1 , the device comprises (rod-shaped and / or tubular) anodes (8) and (tubular) cathodes (9) which are alternately vertically arranged in the particle electrode bed. The particle electrode bed is layered with particle electrode A (5) and particle electrode B (4), wherein the particle electrode A (5) is filled in the bottom layer, and the particle electrode B (4) is filled in the upper layer of the particle electrode A (5). The device further comprises a direct current power supply (10) connected with the anode (8) and the cathode (9) respectively, an ozone generator (7) connected with the upper end of the cathode (9) through a gas pipeline, preferably a gas flow meter (6) is arranged between the cathode (9) and the ozone generator (7) for monitoring and adjusting the amount of ozone. The ozone generator is connected with an oxygen source (12) for producing ozone from oxygen and introducing the ozone into the device through the cathode. Preferably, the device can further comprise a tail gas destroyer (13) for treating the collected tail gas (mainly unoxidized ozone) to avoid secondary pollution. In use, the wastewater to be treated can be stored in the water inlet tank (1) and introduced into the device under the action of the water inlet pump (2). Preferably, a water inlet flow meter (3) is arranged between the water inlet pump (2) and the device for controlling the water inlet amount of the wastewater. The treated wastewater is introduced into the water outlet tank (11) through the water outlet for collection and sampling detection.

[0077] The device provided by the application realizes multi-path generation of ·OH on the basis of electrochemical (three-dimensional electrode) coupling ozone oxidation, effectively improves the generation amount of ·OH, and thus improves the treatment effect of wastewater. For example, the device provided by the application can generate ·OH through the following several ways:

[0078] (a) Electrochemical cathode production of hydrogen peroxide

[0079]

[0080]

[0081] (b) Electrochemical anode production of ·OH

[0082] M+H2O→M(HO·)+H + +e - Formula (3)

[0083] 2M(HO·)→2MO+H2O2Formula (4)

[0084] (c) Catalytic ozone oxidation to produce ·OH

[0085]

[0086]

[0087]

[0088]

[0089]

[0090] (d) Ozone / hydrogen peroxide oxidation to produce ·OH

[0091] O3+H2O2→H2O+O2+HO2·+HO·Formula (10)

[0092] Since the device provided by the application has multiple ways to generate ·OH and a large amount of ·OH, the oxidation effect on ammonia nitrogen is good (the ammonia nitrogen oxidation principle is shown in the following formulas (11)-(13)), so that efficient oxidation treatment of ammonia nitrogen can be realized without additional addition of Cl-.

[0093] 2NH3+M(·OH)6→N2+6H2O+MFormula (11)

[0094]

[0095]

[0096] The second aspect of the present application provides a wastewater treatment method, which comprises passing wastewater into the device as described in the first aspect above, and oxidizing organic matters in the wastewater by electrochemical coupling with ozone oxidation, so as to remove the organic matters in the wastewater.

[0097] The method provided by the present application can be used for treating wastewater containing organic matters. In order to ensure the treatment effect, according to the preferred embodiment of the present application, the COD content in the wastewater is 200-2000 mg / L, the conductivity is not less than 3000 μS / cm, preferably 3000-10000 μS / cm, the ammonia nitrogen content is 80-400 mg / L, and the pH is 6-8.5. Generally, when the TDS (soluble solids) in the wastewater is detected, the conductivity can be measured, so the conductivity of the wastewater reflects the content of TDS in the wastewater to a certain extent. The conductivity is proportional to the TDS content (mg / L), and when the conductivity is <10 ms / cm, it is generally considered that the TDS content (mg / L) = 0.5 x conductivity (mS / cm).

[0098] Since the wastewater treatment device provided by the present application has multiple ·OH generation pathways, the oxidation effect is good, and the treatment efficiency of ammonia nitrogen in the wastewater is high, the dependence on chlorine ions (additional addition) is small. According to the preferred embodiment of the present application, the method does not include the operation of additionally adding a chlorine-containing compound to the device. The chlorine-containing compound refers to a compound that provides Cl - for the wastewater treatment system, which can be a gas (such as Cl2, HCl, etc.), or a liquid or solid (such as hydrochloric acid, hypochlorous acid and its salts, etc., or its aqueous solution, etc.).

[0099] According to the preferred embodiment of the present application, the method comprises oxidizing organic matters (such as COD, ammonia nitrogen, etc.) in the wastewater by at least one of the following products:

[0100] (a) hydrogen peroxide generated at the cathode under the action of electrochemistry;

[0101] (b) ·OH generated at the anode under the action of electrochemistry;

[0102] (c) passing ozone into the wastewater through the tubular cathode to generate ·OH by catalytic ozone oxidation;

[0103] (d) passing ozone into the wastewater through the tubular cathode to generate ·OH by the reaction of ozone and hydrogen peroxide generated in (a).

[0104] The conditions for treating wastewater in the present application are not particularly limited, and can be adjusted according to actual conditions and water quality of the influent and effluent. In order to improve the treatment efficiency and effect of organic matter in wastewater, while controlling the consumption of electricity and ozone, and reducing the treatment cost, according to a preferred embodiment of the present application, the treatment conditions in the method (when treating wastewater with the above water quality) include: a hydraulic retention time of 10-100 min, an ozone flow rate of 0.1-1 L / min / L of wastewater, an ozone concentration of 10-100 mg / L, and a current density of 10-100 mA / cm 2 .

[0105] Preferably, the treatment conditions in the method include: a hydraulic retention time of 10-30 min, an ozone flow rate of 0.1-0.5 L / min / L of wastewater, an ozone concentration of 20-50 mg / L, and a current density of 10-30 mA / cm 2 .

[0106] The present application will be described in detail below by way of examples. It should be understood that the following examples are only used to exemplarily further explain and illustrate the content of the present application, and are not used to limit the present application.

[0107] In the following examples, the concentrated polytetrafluoroethylene dispersion liquid (concentration 60% by weight) was purchased from Aladdin Biochemical Technology Co., Ltd., CAS No. 9002-84-0. Unless otherwise specified, the reagents used were commercially available products purchased from regular chemical reagent suppliers, with a purity of analytical grade.

[0108] In the following examples, the detection method of water quality refers to "Determination of Chemical Oxygen Demand in Water by Dichromate Method" (HJ828-2017) and "Determination of Ammonia Nitrogen in Water by Distillation-Neutralization Titration Method" (HJ537-2009). The COD removal rate and ammonia nitrogen removal rate were calculated using the following formulas:

[0109] COD removal rate = (influent COD - effluent COD) / influent COD x 100%

[0110] Ammonia nitrogen removal rate = (influent ammonia nitrogen - effluent ammonia nitrogen) / influent ammonia nitrogen x 100%

[0111] Preparation Example 1

[0112] (I) Preparation of particle electrode A

[0113] (1) The carbon fiber material (purchased from Shenzhen Yatade Technology Co., Ltd., with an average density of 1.7±0.05 g / cm 3, carbon content greater than 98%, monofilament diameter 7 μm) was sequentially immersed in 20% by volume methanol, 20% by volume ethanol, and 20% by volume acetone for 15 minutes each at 25°C.

[0114] (2) The carbon fiber material was removed and immersed in a polytetrafluoroethylene dispersion (prepared by diluting a concentrated polytetrafluoroethylene dispersion with deionized water to a polytetrafluoroethylene content of 10% by weight) for 3 hours.

[0115] (3) The carbon fiber material after immersion was removed and placed in a muffle furnace and heated at a rate of 5°C / min to 420°C and held at 420°C for 60 minutes. Particle electrode A was obtained.

[0116] (B) Preparation of a tubular anode

[0117] A tubular Ti electrode with an inner diameter of 2 cm, an outer diameter of 2.2 cm, and a height of 30 cm was etched by immersion in an aqueous oxalic acid solution (10% by weight) at 60°C for 10 minutes. The surface of the electrode rod was observed to be gray. The rod was removed and placed in an electroplating solution (0.25 M Pb(NO3)2+ 0.1 M HNO3) and a current of 20 mA / cm2was applied under constant current conditions (the current varied by no more than 2 mA during the electrolysis process) at 20°C for 10 minutes. Hydrogen was generated on the surface of the electrode during the electrodeposition process, resulting in a porous structure of the PbO2coating on the surface. A Ti / PbO2tubular anode was obtained. The average pore diameter of the porous PbO2on the surface was determined to be 5 ± 2 μm. 2 Current, electrodeposition for 10 minutes. Hydrogen was generated on the surface of the electrode during the electrodeposition process, resulting in a porous structure of the PbO2coating on the surface. A Ti / PbO2tubular anode was obtained. The average pore diameter of the porous PbO2on the surface was determined to be 5 ± 2 μm.

[0118] (C) Preparation of a tubular cathode

[0119] A Ti metal tube or a Ti / PbO2metal tube (the Ti / PbO2metal tube was prepared in the same manner as the rod-shaped anode) with an inner diameter of 2 cm, an outer diameter of 2.2 cm, and a height of 30 cm was used to prepare a tubular cathode by loading 0.5% by weight of polytetrafluoroethylene on the inner and outer surfaces of the tube.

[0120] The polytetrafluoroethylene was loaded as follows:

[0121] (1) The above tubular metal electrode was sequentially immersed in 20% by volume methanol, 20% by volume ethanol, and 20% by volume acetone for 15 minutes each at 25°C.

[0122] (2) The clean tubular metal electrode was removed and immersed in a polytetrafluoroethylene dispersion (prepared by diluting a concentrated polytetrafluoroethylene dispersion with deionized water to a polytetrafluoroethylene content of 10% by weight) for 3 hours.

[0123] (3) The tubular metal electrode loaded with polytetrafluoroethylene was taken out and placed in a muffle furnace, and heated to 520°C at a rate of 5°C / min, and kept at 520°C for 240 min. A tubular cathode loaded with polytetrafluoroethylene was obtained.

[0124] (IV) Assembly of the wastewater treatment device

[0125] Reference Figure 1 The tubular anode (8) and the tubular cathode (9) were evenly and alternately vertically arranged on the particle electrode bed layer with a bottom area of 400 cm 2 (20 cm x 20 cm) (the electrode height direction is perpendicular to the bed layer bottom surface), wherein the bottom of the tubular cathode was provided with an aeration port located at 1 / 4 of the electrode bottom. The particle electrode A (5) and the particle electrode B (4) were layered and loaded in the particle electrode bed layer, wherein the particle electrode A was loaded in the lower layer and the particle electrode B was loaded in the lower layer. The direct current power supply (10) was connected to the tubular anode and the tubular cathode, respectively. The ozone generator (7) connected to the oxygen source (12) was connected to the top of the tubular cathode through a pipeline, and a gas flow meter (6) was arranged between the tubular cathode and the ozone generator. The wastewater was taken from the water inlet tank (1) and entered the wastewater treatment device under the action of the water inlet pump (2), and a water inlet flow meter (3) was arranged between the water inlet pump (2) and the treatment device. The treated effluent entered the effluent tank (11). An exhaust gas destroyer (13) was also arranged above the device for treating unoxidized ozone.

[0126] Example 1

[0127] A wastewater treatment device assembled in Preparation Example 1 was used to treat a certain pesticide production wastewater. In the wastewater, the COD was 956 mg / L, the ammonia nitrogen was 297 mg / L, the pH was 7.4, the conductivity was 3545 μS / cm, and the B / C was 0.1. In the device, the tubular cathode was made of a Ti / PbO2 metal tube, and 8 tubular anodes and 8 tubular cathodes were evenly and alternately distributed on the bottom surface of the particle electrode bed layer (for details, see Figure 2 (a)), the distance between adjacent two electrodes was 2 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed layer was 2.6 cm. The particle electrode B used was a spherical catalyst of γ-Al2O3 loaded with CuO and Co (particle size 3-6 mm, screened by a sieve with a pore size of 3 mm and 6 mm), and the loading amount of Cu and Co in the particle electrode B was 0.2% and 0.5% by weight, respectively. The loading layer thickness of the particle electrode A and the particle electrode B was 5 cm, and the height of the tubular anode and the tubular cathode covered by the particle electrode A and B was 10 cm.

[0128] The process parameters during the treatment process include: hydraulic retention time of 15 min, ozone flow of 0.2 L / min / L wastewater, ozone concentration of 40 mg / L, and current density of 20 mA / cm 2 .

[0129] The effluent water quality is detected, and B / C is increased to 0.35, reaching the biodegradability treatment standard (B / C>0.3). According to the detection results, the COD removal rate is 82.5%, and the ammonia nitrogen removal rate is 96.3%.

[0130] Example 2

[0131] The wastewater treatment device in Example 1 is used to treat a certain dye production wastewater. In the wastewater, COD is 1642 mg / L, ammonia nitrogen is 368 mg / L, pH is 8.3, conductivity is 4657 μS / cm, and B / C is 0.08. The difference is that the particle electrode B loaded in the device is a spherical catalyst (particle size 3-6 mm) of γ-Al2O3 loaded with CuO and Mn, and the loading amount of Cu and Mn is 0.3% by weight in terms of elements.

[0132] The process parameters during the treatment process include: hydraulic retention time of 20 min, ozone flow of 0.2 L / min / L wastewater, ozone concentration of 30 mg / L, and current density of 25 mA / cm 2 .

[0133] The effluent water quality is detected, and B / C is increased to 0.32, reaching the biodegradability treatment standard. According to the detection results, the COD removal rate is 81.5%, and the ammonia nitrogen removal rate is 95.7%.

[0134] Example 3

[0135] The method in Example 1 is used to treat a certain pesticide production wastewater. The wastewater has the same water quality as the wastewater treated in Example 1. The difference is that in the device used, 4 rod-shaped anodes and 4 tubular cathodes are evenly and alternately distributed on the bottom surface of the particle electrode bed (see Figure 2 (b) for details of electrode position distribution), the distance between the front and rear two rows of electrodes is 6 cm, the distance between the adjacent two electrodes in the same horizontal row is 2 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed is 4.8 cm / 2.6 cm.

[0136] The remaining parameters and conditions are the same as those in Example 1. The effluent water quality is detected, and B / C is increased to 0.31. According to the detection results, the COD removal rate is 75.5%, and the ammonia nitrogen removal rate is 86.4%.

[0137] Example 4

[0138] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that in the device used, 12 rod-shaped anodes and 13 tubular cathodes were evenly and alternately distributed on the bottom surface of the particle electrode bed (the electrode position distribution diagram is shown in detail in Figure 2 (c)), the distance between the front and rear rows of electrodes was 0.8 cm, the distance between the adjacent two electrodes in the same horizontal row was 2 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed was 2.6 cm / 1.4 cm.

[0139] The rest of the parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.39. According to the detection results, the COD removal rate was 85.1%, and the ammonia nitrogen removal rate was 99%.

[0140] Example 5

[0141] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that in the device used, 12 rod-shaped anodes and 13 tubular cathodes were evenly and alternately distributed on the bottom surface of the particle electrode bed (the electrode position distribution diagram is shown in detail in Figure 2 (d)), the distance between the adjacent two electrodes was 1.5 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed was 1.5 cm.

[0142] The rest of the parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.39. According to the detection results, the COD removal rate was 87.1%, and the ammonia nitrogen removal rate was 99.1%.

[0143] Example 6

[0144] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that in the device used, 12 rod-shaped anodes and 13 tubular cathodes were evenly and alternately distributed on the bottom surface of the particle electrode bed (the electrode position distribution diagram is shown in detail in Figure 2 (e)), the distance between the adjacent two electrodes was 1.5 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed was 1.5 cm.

[0145] The rest of the parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.38. According to the detection results, the COD removal rate was 86.9%, and the ammonia nitrogen removal rate was 99%.

[0146] Example 7

[0147] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the tubular cathode in the device was not loaded with polytetrafluoroethylene on the inner and outer surfaces.

[0148] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.25. According to the detection results, the COD removal rate was 50.2%, and the ammonia nitrogen removal rate was 70.4%.

[0149] Example 8

[0150] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the tubular Ti electrode with an inner diameter of 2 cm, an outer diameter of 2.2 cm, and a height of 30 cm was directly used as the anode in the device.

[0151] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.28. According to the detection results, the COD removal rate was 72.2%, and the ammonia nitrogen removal rate was 84.3%.

[0152] Example 9

[0153] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the tubular cathode in the device was made of Ti metal pipe according to the method in Preparation Example 1.

[0154] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.33. According to the detection results, the COD removal rate was 84.7%, and the ammonia nitrogen removal rate was 97.8%.

[0155] Example 10

[0156] The method in Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that NaCl 4000 mg / L was added to the wastewater during the treatment process.

[0157] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.35. According to the detection results, the COD removal rate was 82.8%, and the ammonia nitrogen removal rate was 96.4%.

[0158] By comparing the treatment effects of this example and Example 1, it can be seen that although the COD and ammonia nitrogen removal rates in this example are slightly higher than those in Example 1, NaCl needs to be added during the treatment process. This not only makes the operation cumbersome, but also increases the reagent cost of wastewater treatment, which is not conducive to industrial application.

[0159] Example 11

[0160] The method of Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the tubular cathode in the device was centrally arranged in the catalytic reactor (the electrode position distribution diagram is shown in detail in Figure 2 (f)), the distance between adjacent electrodes was 2 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed was 2.6 cm.

[0161] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.27. According to the detection results, the COD removal rate was 70.7%, and the ammonia nitrogen removal rate was 74.3%.

[0162] Example 12

[0163] The method of Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the rod-shaped anode and the tubular cathode in the device were arranged separately, and the ozone generator in the device was not connected to the tubular cathode, but was arranged with 8 dispersed pipelines for aeration (the electrode position distribution diagram is shown in detail in Figure 2 (g)), the distance between adjacent electrodes was 2 cm, and the distance between the outermost electrode and the side wall of the particle electrode bed was 2.6 cm.

[0164] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.27. According to the detection results, the COD removal rate was 70.7%, and the ammonia nitrogen removal rate was 74.3%.

[0165] Comparative Example 1

[0166] The method of Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the direct current power connected to the rod-shaped anode and the tubular cathode was turned off during the treatment process (i.e., the treatment was carried out without applying current).

[0167] The remaining parameters and conditions were the same as in Example 1. The effluent quality was detected, and the B / C was increased to 0.19. According to the detection results, the COD removal rate was 61.2%, and the ammonia nitrogen removal rate was 42.4%.

[0168] Comparative Example 2

[0169] The method of Example 1 was used to treat a certain pesticide production wastewater. The wastewater was the same as the wastewater treated in Example 1. The difference was that the ozone generator was not turned on during the treatment process (i.e., the treatment was carried out without ozone).

[0170] The rest of the parameters and conditions are the same as those in Example 1. The effluent water quality is detected, and the B / C is increased to 0.18. According to the detection results, the COD removal rate is 25.7%, and the ammonia nitrogen removal rate is 62.4%.

[0171] The above describes the preferred embodiments of the present application, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A wastewater treatment apparatus, characterized by, The device comprises a particle electrode bed layer, an anode and a cathode arranged on the particle electrode bed layer, wherein the anode is a rod-shaped anode and / or a tubular anode, the cathode is a tubular cathode with aeration function, and the anode and the cathode are arranged perpendicularly to the bottom of the particle electrode bed layer. The particle electrode bed layer is layered with particle electrode A and particle electrode B, the particle electrode A is a carbon fiber material loaded with polytetrafluoroethylene, and the particle electrode B is a catalyst with γ-Al2O3 as carrier and transition metal as active component.

2. The apparatus of claim 1, wherein, The particle electrode A is loaded in the lower layer and the particle electrode B is loaded in the upper layer in the particle electrode bed layer. The loading amount of the particle electrode is such that the thickness ratio of the particle electrode A loading layer to the particle electrode B loading layer is 1:1-2.

3. The apparatus of claim 1 or 2, wherein, The loading amount of polytetrafluoroethylene in the particle electrode A accounts for 0.1-3% of the total weight of the particle electrode A.

4. The apparatus of claim 3, wherein, The preparation method of the particle electrode A comprises: (1) soaking clean carbon fiber material in polytetrafluoroethylene dispersion liquid for 1-5h; (2) placing the soaking product in a muffle furnace, heating at a rate of 1-10℃ / min to 400-450℃, and keeping at the temperature for 50-100min; The loading amount of the transition metal in the particle electrode B is not less than 0.2% based on the total weight of the catalyst.

5. The apparatus of claim 4, wherein, The content of polytetrafluoroethylene in the polytetrafluoroethylene dispersion liquid is 5-10%; The transition metal is at least one selected from Mn, Cu, Ce, Co, and Co.

6. The apparatus of claim 1, wherein, The anode is a Ti / PbO2 electrode; The cross-sectional area of the anode is 0.5-8% of the total bottom area of the particle electrode bed layer; And / or, relative to 1m 2 The bottom surface of the particle electrode bed, wherein the number of anodes is set to 8-128.

7. The apparatus of claim 6, wherein, The material of the anode is Ti loaded with porous PbO2; The height-diameter ratio of the anode is 10-50, and the ratio of the outer diameter to the inner diameter of the tubular anode is 1.1-1.

2.

8. The apparatus of claim 7, wherein, The average pore size of the porous PbO2 is 1-10μm; The height of the anode covered by the particle electrode loaded in the particle electrode bed layer is 25-50% of the height of the anode.

9. The apparatus of claim 1, wherein, The cathode comprises a tubular metal electrode and polytetrafluoroethylene loaded on the tubular metal electrode; The cross-sectional area of the cathode is 0.5-8% of the total bottom area of the particle electrode bed layer; and / or, relative to 1 m 2 of the particle electrode bed floor, the number of cathodes is set to 8-128 The preparation method of the cathode comprises: (1) soaking clean tubular metal electrode in polytetrafluoroethylene dispersion liquid for 1-5h; (2) placing the soaking product in a muffle furnace, heating at a rate of 1-10℃ / min to 500-600℃, and keeping at the temperature for 60-360min.

10. The apparatus of claim 9, wherein, The polytetrafluoroethylene accounts for 0.1-1% of the total weight of the cathode; The tubular metal electrode is a Ti or Ti / PbO2 electrode; The height-diameter ratio of the tubular cathode is 10-50, and the ratio of the outer diameter to the inner diameter is 1.1-1.2; The height of the cathode covered by the particle electrode loaded in the particle electrode bed layer is 25-50% of the height of the cathode; The content of polytetrafluoroethylene in the polytetrafluoroethylene dispersion liquid is 10-20%.

11. The apparatus of any of claims 1 and 6-10, wherein, The distance between the anode and its adjacent cathode is 0.6-5 times of the diameter of the anode; And / or, in the device, the number ratio of the anode to the cathode is 1:0.5-1.

5.

12. The apparatus of claim 1, wherein, The device further comprises a direct current power source, an ozone generator and a tail gas destroyer.

13. The apparatus of claim 12, wherein, The direct current power source is connected to the anode and the cathode respectively; And / or, the ozone generator is connected to the gas inlet at the top of the tubular cathode, so that the ozone is introduced into the device through the tubular cathode; And / or, the tail gas destroyer is connected to the exhaust outlet of the device to remove the residual ozone in the tail gas.

14. A method of wastewater treatment, characterized by, The method comprises introducing the wastewater into the device of any one of claims 1-13, and oxidizing the organic matters in the wastewater by electrochemical and ozone oxidation coupling, so as to remove the organic matters in the wastewater.

15. The method of claim 14, wherein, The COD content of the wastewater is 200-2000 mg / L, the conductivity is not less than 3000 μS / cm, the ammonia nitrogen content is 80-400 mg / L, and the pH is 6-8.5; And / or, the method does not comprise the operation of adding chlorine-containing compounds into the device.

16. The method of claim 15, wherein, The conductivity of the wastewater is 3000-10000 μS / cm.

17. The method of claim 14, wherein, The method comprises oxidizing the organic matters and ammonia nitrogen in the wastewater by at least one of the following products: (a) hydrogen peroxide generated at the cathode under electrochemical action; (b) ·OH generated at the anode under electrochemical action; (c) ozone introduced into the wastewater through the tubular cathode, and ·OH is generated by the catalytic action of the particle electrode on the ozone; (d) ozone introduced into the wastewater through the tubular cathode, and ·OH is generated by the reaction of the ozone and the hydrogen peroxide generated in (a).

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