Method and system for degradation treatment of organic wastewater

Abstract

The application relates to a degradation treatment method and system of organic wastewater; the method comprises the following steps: adjusting the pH of the organic wastewater to be acidic; adding the acidic organic wastewater and hydrogen peroxide into a photoelectric oxidation unit, the hydrogen peroxide generates hydroxyl radicals for degrading the acidic organic wastewater by generating an electro-Fenton reaction with an electrode group in the photoelectric oxidation unit, and the hydroxyl radicals are regenerated through an electrochemical reaction and a conjugate effect excited by ultraviolet light; the pH of the wastewater treated by the photoelectric oxidation is adjusted to be alkaline, a flocculating agent is added into the alkaline wastewater, sludge precipitation and supernatant are obtained, and the supernatant is subjected to subsequent treatment. 2+ The application adopts a full-amount high-efficiency utilization mode of a catalyst of a trace iron sludge precipitation generated by a natural precipitation of an inductive iron electrode, electrochemistry and ultraviolet light reduction, improves the regeneration rate of ferrous ions and hydroxyl radicals, and further promotes the degradation of organic matters in the organic wastewater.

Description

Technical Field

[0001] This invention relates to the field of organic wastewater degradation technology, and in particular to a method and system for the degradation and treatment of organic wastewater. Background Technology

[0002] Resource-based treatment of wastewater has become a hot topic in the environmental protection industry. Wastewater treatment is the process of removing pollutants from wastewater or sewage and converting it into water that can be recycled or directly reused with minimal environmental impact. Its purpose is to reduce pollutants in wastewater to acceptable levels, ensuring that the water can be safely discharged back into the environment or used for other non-potable purposes, such as industrial use or irrigation. Currently, organic wastewater treatment in the industry typically employs physical or biochemical methods to remove organic matter, but these methods often fail to achieve resource recovery. Therefore, there is an urgent need for a degradation treatment method and system for organic wastewater to address the persistent organic pollutants in the current water environment and achieve water environmental safety and sustainable development. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for the degradation and treatment of organic wastewater, comprising the following steps:

[0004] Adjust the pH of the organic wastewater to acidic;

[0005] Acidic organic wastewater and hydrogen peroxide are added to the photoelectric oxidation unit. The hydrogen peroxide reacts with the electrode assembly in the unit via an electro-Fenton reaction to generate hydroxyl radicals that degrade the acidic organic wastewater. Through electrochemical reaction and ultraviolet light excitation, the Fe in the solution is activated. 2+ and hydroxyl radical regeneration;

[0006] The pH of the wastewater after photoelectro-oxidation treatment is adjusted to alkaline. Flocculants are added to the alkaline wastewater to obtain sludge sediment and supernatant. The supernatant is then subjected to further treatment.

[0007] Furthermore, the electrode group is a plurality of groups, each electrode group including a first anode, a second anode and a carbon-based cathode, the first anode and the second anode are arranged alternately, the first anode is a carbon-based anode and the second anode is an induction iron-based anode, and the spacing between each adjacent electrode is 1 to 2 mm.

[0008] Furthermore, the method for preparing the carbon-based anode is as follows:

[0009] 1) Add additives to carbon-based raw material powder, stir and mix, and extrude the mixture to obtain carbon-based products;

[0010] 2) The carbon-based product is roasted to carbonize the additives;

[0011] 3) The calcined carbon-based product is impregnated with an impregnating agent, which penetrates into the electrode pores of the carbon-based product;

[0012] 4) The impregnated carbon-based products are then subjected to a second firing to carbonize the impregnating agent;

[0013] 5) The carbon-based product after secondary roasting is subjected to high-temperature calcination at a temperature not lower than 2300℃ to obtain a carbon-based anode.

[0014] Further, step 1), specifically the extrusion molding of the mixture, includes the following steps:

[0015] Cooling: Remove volatile components from the mixture, then lower the temperature of the mixture to 90-120 ℃ and keep it warm for 20-30 min;

[0016] Loading: Compact the cooled mixture at 4-10 MPa for 2-3 min;

[0017] Pre-compression: Compact the mixture at 20-25 MPa for 3-5 min, while simultaneously applying a vacuum.

[0018] Extrusion: The pre-compressed mixture is extruded at 5-15 MPa, then sheared and cooled to obtain carbon-based products.

[0019] Furthermore, in step 3), the impregnation of the carbon-based product specifically includes the following steps:

[0020] Clean the surface of the calcined carbon-based product and preheat it to 260-380 ℃, then keep it at that temperature for 6-10 hours.

[0021] The preheated carbon-based product is placed into an impregnation tank, the tank is evacuated, and then an impregnation agent is injected into the impregnation tank.

[0022] Pressurize the tank to 1.2-1.5 MPa, immerse for 3-4 hours, and then cool to complete the impregnation of carbon-based products.

[0023] Furthermore, the carbon-based cathode is prepared by placing carbon-based raw materials in a high-temperature furnace, evacuating the furnace or introducing inert gas, heating it to 2200-2500 ℃ at a heating rate of 100-300 ℃ / h, holding it at that temperature for a period of time, and then cooling it to obtain the carbon-based cathode.

[0024] Furthermore, the measured value of ORP within the photoelectro-oxidation unit is monitored. If the measured value of ORP is less than the set value of ORP, the amount of hydrogen peroxide added is increased until the measured value of ORP equals the set value of ORP; if the measured value of ORP is greater than the set value of ORP, the amount of hydrogen peroxide added is decreased until the measured value of ORP equals the set value of ORP.

[0025] Furthermore, the iron ion concentration in the photoelectric oxidation unit is 20 mg / L to 40 mg / L. If the detected iron ion concentration is less than 20 mg / L, the anode voltage is increased; if the detected iron ion concentration is greater than 40 mg / L, the anode voltage is decreased.

[0026] Furthermore, after adding flocculant to the alkaline organic wastewater, sedimentation is carried out, and the sediment is backwashed using a backwashing device with a backwashing intensity of 20~80 m. 3 / (m 2 *h); A portion of the sludge is precipitated and returned to the alkaline wastewater.

[0027] On the other hand, the present invention also provides a treatment system for degrading organic wastewater, comprising:

[0028] The pH adjustment unit is used to adjust the pH of organic wastewater to acidic.

[0029] The photoelectro-oxidation unit includes an electrolytic cell and an ultraviolet lamp mounted on the electrolytic cell. The feed inlet of the electrolytic cell is connected to the discharge outlet of the acid adjustment unit. Several electrode groups are provided inside the electrolytic cell.

[0030] An alkali adjustment unit is used to adjust the pH of organic wastewater to alkaline, and the alkali adjustment unit is connected to the electrolytic cell;

[0031] The flocculation and sedimentation unit includes a flocculation tank and a sedimentation tank. The flocculation tank is connected to the alkali adjustment unit, and the sedimentation tank is connected to the flocculation tank.

[0032] By employing the above technical solutions, this invention has the following advantages compared to existing technologies:

[0033] 1) The organic wastewater degradation treatment method provided by this invention adopts a combination of carbon-based anode, carbon-based cathode, induction iron-based anode, and carbon-based cathode in the electrode group of the photoelectric oxidation unit. The photoelectric oxidation unit is also equipped with an ultraviolet lamp. It adopts a catalyst full-quantity high-efficiency utilization mode of natural precipitation, electrochemical and ultraviolet light reduction of induction iron electrode and trace iron mud precipitation, thereby improving the regeneration rate of ferrous ions and hydroxyl radicals. Through the photoelectric coupling chemical oxidation synergistic mechanism, it overcomes the strong quenching effect of complex wastewater components on traditional free radicals. Through the radiation effect of ultraviolet light, it improves the catalyst circulation efficiency and free radical generation rate, thereby promoting the degradation of organic matter in organic wastewater.

[0034] 2) The organic wastewater degradation treatment method provided by the present invention prepares carbon-based anodes and carbon-based cathodes through different methods to meet different electrode usage requirements, and realizes resource recycling and low-carbon green treatment of wastewater.

[0035] 3) The degradation treatment method for organic wastewater provided by the present invention improves the utilization rate of hydrogen peroxide by 10%, reduces operating costs by 40%, and reduces sludge production by 60% through the interlocking control of online iron ion monitoring and DC power supply.

[0036] 4) The organic wastewater degradation treatment method provided by the present invention achieves rapid sludge sedimentation and stable effluent through seed crystal growth and backwashing in the flocculation sedimentation unit, which greatly reduces the cost of reagents and labor. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0038] Figure 1 A schematic diagram of the structure of the organic wastewater degradation treatment system provided by the present invention;

[0039] Figure 2 This is a schematic diagram of the photoelectric oxidation unit in the organic wastewater degradation treatment system provided by the present invention.

[0040] Figure 3 This is a schematic diagram of the flocculation and sedimentation unit in the organic wastewater degradation treatment system provided by the present invention.

[0041] 1-Acid adjustment unit; 11-Pipeline mixer; 12-Sulfuric acid tank; 13-Acid adjustment tank; 14-Agitator; 15-pH online monitor; 16-Level gauge; 2-Photoelectric oxidation unit; 21-Electrolytic cell; 22-Ultraviolet lamp; 23-Hydrogen peroxide tank; 24-Circulation pump; 25-Electrode group; 26-DC power supply; 3-Alkali adjustment unit; 31-Neutralization tank; 32-Alkali tank; 33-Buffer tank; 4-Flocculation and sedimentation unit; 41-First flocculation tank; 42-Second flocculation tank; 43-Sedimentation tank; 44-PAC tank; 45-PAM tank; 46-High-pressure pulse blower; 47-Backwash duct. Detailed Implementation

[0042] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. In the accompanying drawings, the dimensions and relative dimensions of certain parts may be enlarged for clarity.

[0043] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connection" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two elements or the interaction between two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0044] In the description of this invention, terms such as "upper," "lower," "left," "right," "front," and "rear," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0045] Furthermore, in the description of this invention, the terms "first" and "second" are used merely for descriptive distinction and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Additionally, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0046] Example 1

[0047] This invention provides a method for the degradation and treatment of organic wastewater, comprising the following steps:

[0048] Adjust the pH of the organic wastewater to acidic;

[0049] Acidic organic wastewater and hydrogen peroxide are added to the photoelectric oxidation unit 2. The hydrogen peroxide reacts with the electrode assembly 25 in the photoelectric oxidation unit 2 via an electro-Fenton reaction to generate hydroxyl radicals for degrading the acidic organic wastewater. Through electrochemical reaction and ultraviolet light excitation conjugation, Fe in the solution is reduced. 2+ and hydroxyl radical regeneration;

[0050] The pH of the wastewater after photoelectro-oxidation treatment is adjusted to alkaline. Flocculants are added to the alkaline wastewater to obtain sludge sediment and supernatant. The supernatant is then subjected to further treatment.

[0051] In an optimized implementation, the electrode group 25 comprises multiple groups, each including a first anode, a second anode, and a carbon-based cathode. The first anode and the second anode are spaced apart, i.e., a carbon-based cathode is positioned between the first anode and the second anode. The first anode is a carbon-based anode that is energized, while the second anode is an inductive iron-based anode that does not require energization. The spacing between adjacent electrodes is 1–2 mm. In this embodiment, each electrode group 25 includes a carbon-based anode, an inductive iron-based anode, and two carbon-based cathodes. The electrode sheets are arranged in the order of carbon-based anode, carbon-based cathode, inductive carbon-based anode, and carbon-based cathode, with a spacing of 1–2 mm between adjacent electrodes. For example, the spacing between the inductive iron-based anode and the adjacent carbon-based cathode is 1–2 mm. The carbon-based anode and the carbon-based cathode form an electric field through an external power source. Under the action of the electric field, the inductive iron-based anode spontaneously precipitates ferrous ions without the need for an external power source.

[0052] Preferably, the pH of the organic wastewater is adjusted to 4-5 to obtain acidic organic wastewater. This acidic wastewater is then passed into a photoelectric oxidation unit, which is circulated with hydrogen peroxide to form an electrolytic cell with the electrode assembly. The inductive iron-based anodic oxidation precipitates Fe. 2+ Fe 2+ Hydroxyl radicals (·OH) are generated by the Fenton reaction with hydrogen peroxide (see Formula 1). Hydroxyl radicals have strong oxidizing properties and can oxidize complex, difficult-to-biodegrade organic matter, thus effectively degrading organic wastewater. The degraded organic wastewater is then prepared to be alkaline, and a flocculant is added. The pollutants in the organic wastewater mix with the flocculant to form flocs, which are then precipitated to obtain precipitated sludge and supernatant. The supernatant can proceed to the next treatment step, while the precipitated sludge can be concentrated and collected.

[0053] Fe 2+ +H₂O₂→Fe 3+ +·OH+OH - 1)

[0054] Fe generated by the electro-Fenton reaction 3+ It is reduced to Fe by the cathode. 2+ The reaction continues with hydrogen peroxide to produce hydroxyl radicals, which are then induced to undergo anodic oxidation to dissolve Fe. 2+ The rate is much greater than that of Fe 3+ The reduction rate of Fe 2+ It reacts with hydrogen peroxide to produce more Fe. 3+ This leads to the formation of iron sludge, which requires Fe... 2+ And the regeneration of hydroxyl radicals. Ultraviolet light and Fe 2+ Both can catalyze the decomposition of H2O2 to produce ·OH, and they exhibit a synergistic effect on the catalytic decomposition of H2O2 to produce ·OH. This is because certain hydroxyl complexes of iron, at pH values ​​of 3–5, [are affected by / affect the formation of ·OH].3+ With Fe(OH) 2+ It exists in a form with good light absorption properties and can undergo a photosensitization reaction to generate more ·OH (the reaction formula is shown in Equation 2). At the same time, it can enhance Fe... 3+ The reduction of Fe 2+ Regeneration. This helps maintain Fe. 2+ The concentration is used to ensure the Fenton reaction continues, thereby reducing the Fe concentration. 2+ Use a sufficient amount of H2O2 to maintain a high utilization rate.

[0055] Fe(OH) 2+ + hv →Fe 2+ +·OH 2)

[0056] In the above formula, the reaction condition is light irradiation (hv), where h represents Planck's constant and v represents the frequency of light. Irradiation with ultraviolet light can promote the reaction of Fe... 2+ In addition to the regeneration of hydroxyl radicals, the consumption of induction iron-based anodes and hydrogen peroxide is reduced. The dual anode configuration consisting of iron and carbon anodes can form a more uniform current distribution in the electrolytic cell.

[0057] In this invention, ultraviolet light and electrochemical reduction techniques are introduced to accelerate the reduction of Fe. 2+ The regeneration and efficient utilization of ·OH reduce sludge production by 60%, increase hydrogen peroxide utilization by 10%, and reduce operating costs by 40%.

[0058] The optimized implementation method is as follows:

[0059] 1) Add additives to carbon-based raw material powder, stir and mix, and extrude the mixture to obtain carbon-based products.

[0060] Specifically, the carbon-based raw material is bio-stalk, graphite, etc., and the additive is at least one of coal tar, asphalt, and resin. The amount of additive added is 0.5-1% of the carbon-based raw material powder. Before adding the additive, the carbon-based raw material needs to be pulverized into powder, sieved, and the powder with a particle size of 0.5-20 mm is obtained. Then, the powder is ground into fine powder with a particle size of less than 0.075 mm. The additive is added to the carbon-based fine powder and stirred and mixed, wherein dry mixing is performed for 20-35 minutes and wet mixing for 40-55 minutes to obtain a uniformly dispersed mixture. The mixture is placed in a specially made mold for rough shaping, and the rough-shaped mixture is extruded to obtain the carbon-based product.

[0061] 2) The carbon-based products are roasted to carbonize the additives.

[0062] Specifically, the shaped carbon-based product is placed in a heating furnace and calcined under the protection of filler at a temperature of 1050–1360 °C for 320–480 hours to carbonize the additives in the carbon-based product. Calcination of the mixture increases its mechanical strength, reduces its resistivity, and improves its thermal and chemical stability.

[0063] The preferred roasting temperature is 1250 ℃.

[0064] 3) The calcined carbon-based product is impregnated with a liquid impregnating agent, which penetrates into the electrode pores of the carbon-based product.

[0065] Specifically, the calcined carbon-based products are impregnated with a liquid impregnating agent, which penetrates into the electrode pores of the product to reduce porosity, increase bulk density and mechanical strength, and improve the product's electrical and thermal conductivity. Pitch is preferably used as the liquid impregnating agent.

[0066] 4) The impregnated carbon-based products are then subjected to a second firing to carbonize the impregnating agent.

[0067] Specifically, the impregnated carbon-based products are further processed by a second firing at a temperature of 700–800 °C for 120–280 hours, which further carbonizes the asphalt impregnated in the pores of the firing product.

[0068] 5) The carbon-based product after secondary roasting is subjected to high-temperature calcination at a temperature not lower than 2300℃ to obtain a carbon-based anode.

[0069] Specifically, the carbon-based product after secondary calcination is heated and calcined in a high-temperature furnace at a temperature not lower than 2300℃, transforming the amorphous disordered carbon into a three-dimensional ordered graphite crystal structure. Finally, the calcined product is machined, cut and polished to the set shape and size to obtain the carbon-based anode.

[0070] The carbon-based anode prepared by the above method has a bulk density of 1.70 g / cm³. 3 ~1.60g / cm 3 Resistivity 1-9 μO·m, carbon content greater than 99.9%.

[0071] In the optimized implementation method, step 1 involves extruding the coarsely formed mixture in a screw extruder or a horizontal hydraulic extruder, specifically including the following steps:

[0072] Cooling: The volatile components in the mixture are removed by methods such as disc cooling, cylindrical cooling, and kneading cooling. Then the temperature of the mixture is lowered to 90-120 ℃ and kept at that temperature for 20-30 min. This can increase the adhesive strength of the mixture and make the paste block size uniform, which is conducive to molding.

[0073] Loading: Compact the cooled mixture at 4–10 MPa for 2–3 min;

[0074] Pre-compaction: Compact the mixture at 20-25 MPa for 3-5 min, while simultaneously applying a vacuum.

[0075] Extrusion: The pre-compressed mixture is extruded at 5-15 MPa, then sheared into the required size and placed in a cooling water tank to cool, thus obtaining carbon-based products.

[0076] In the optimized implementation method, step 3, the impregnation of the carbon-based product specifically includes the following steps:

[0077] Clean the surface of the calcined carbon-based product and preheat it to 260-380 ℃, then keep it at that temperature for 6-10 hours.

[0078] The preheated carbon-based product is placed into an impregnation tank. The tank is evacuated to a pressure of 8-9 kPa and maintained for 40-50 minutes. Then, asphalt is injected into the impregnation tank at a temperature of 180-200 ℃.

[0079] Pressurize the tank to an internal pressure of 1.2-1.5 MPa, impregnate for 3-4 hours, return the asphalt, and cool the inside and outside of the tank to complete the impregnation of carbon-based products.

[0080] In an optimized implementation method, the carbon-based cathode is prepared as follows: carbon-based raw materials are placed in a high-temperature furnace, which is then evacuated or purged with an inert gas. The furnace is heated to 2200–2500 °C at a heating rate of 100–300 °C / h, held at this temperature for a period of time, and then cooled to obtain the carbon-based cathode. The carbon-based cathode prepared by the above method has a bulk density of 0.20 g / cm³. 3 ~0.10g / cm 3 It has a resistivity of 10–20 μΩ·m and a carbon content greater than 99.9%.

[0081] Preferably, the carbon-based raw material is bio-stalk, graphite, etc., and the high-temperature furnace is a graphite tube furnace, medium-frequency induction furnace, high-frequency induction furnace, or other high-temperature furnaces with heating methods.

[0082] This application presents carbon-based anodes and cathodes prepared by the aforementioned method. The carbon-based cathode, acting as an electron-accepting substrate, reduces ferric iron to ferrous iron and hydrogen ions to hydrogen gas, exhibiting excellent reduction performance. The carbon-based anode, acting as an electron-providing substrate, converts organic matter into carbon dioxide and oxidizes oxygen ions to oxygen gas. An electric field is formed between the carbon-based anode and cathode via an external power source. Under the influence of this electric field, the induced iron-based anode spontaneously precipitates ferrous ions without requiring an external power source. The induced iron-based anode provides ferrous ions to the system, while the carbon-based cathode reduces ferric ions to ferrous ions.

[0083] In an optimized implementation method, the induction iron-based anode is prepared by pressing iron filings under high pressure. The iron filings can be shavings produced during machining. The resulting induction iron-based anode has a large specific surface area and a small overpotential, which degrades pollutants in wastewater while realizing waste recycling.

[0084] The electrolytic cell of the photoelectro-oxidation unit adopts a dual-anode unipolar coupled bipolar combined electrolytic cell. The electrode group adopts a cross combination of carbon-based anodes, carbon-based cathodes, induction iron-based anodes, and carbon-based cathodes. The formula for calculating the number of induction iron-based anodes n is as follows:

[0085] n=Q×C×t / (A×h×ρ / 1000) / 1000 3)

[0086] In Equation 3), Q represents the system's water treatment capacity, in cubic meters per second (m³). 3 / d; C is the system iron ion concentration of 20–40 mg / L; A is the area of ​​the inductive iron-based anode, taken as 1–2 m². 2 h represents the thickness of the induction iron-based anode, ranging from 4 to 10 mm; ρ represents the density of the induction iron-based anode, ranging from 7 to 7.8 g / cm³. 3 t represents the replacement time of the induction iron-based anode, which is 300 to 600 days.

[0087] The spacing between each pair of adjacent electrodes is 1–2 mm. The number of carbon-based anodes is the same as the number of induction iron-based anodes. The number of carbon-based cathodes is twice the number of induction iron-based anodes. The operating voltage is 3–4 V.

[0088] In an optimized implementation method, during the reaction process, the iron ions and ORP (Oxidation-Reduction Potential) in the photoelectro-oxidation unit are monitored online, and the anode voltage and current, as well as the amount of hydrogen peroxide added, are intelligently adjusted by PID control.

[0089] Monitor the measured value of ORP in the photoelectro-oxidation unit. If the measured value of ORP is less than the set value of ORP, increase the amount of hydrogen peroxide added until the measured value of ORP equals the set value of ORP; if the measured value of ORP is greater than the set value of ORP, decrease the amount of hydrogen peroxide added until the measured value of ORP equals the set value of ORP.

[0090] In one embodiment, the ORP setting is 100. When the measured ORP value is less than 100, the hertz of the hydrogen peroxide dosing pump is increased by 5. After a reaction time of 10 seconds, the measured ORP values ​​before and after 10 seconds are compared. If the measured ORP value is still less than 100, the hertz of the hydrogen peroxide dosing pump is increased until the measured ORP value is 100. When the measured ORP value is greater than 100, the hertz of the hydrogen peroxide dosing pump is decreased by 5. After a reaction time of 10 seconds, the measured ORP values ​​before and after 10 seconds are compared. If the measured ORP value is still greater than 100, the hertz of the hydrogen peroxide dosing pump is decreased until the measured ORP value is 100.

[0091] In one embodiment, the iron ion concentration in the photoelectro-oxidation unit is 20 mg / L to 40 mg / L. If the detected iron ion concentration is less than 20 mg / L, the anode voltage is increased; if the detected iron ion concentration is greater than 40 mg / L, the anode voltage is decreased.

[0092] In the optimized implementation, the photoelectro-oxidation unit is equipped with a circulation pipeline for circulating the mixed solution in the electrolytic cell, and an ultraviolet lamp is installed on the circulation pipeline. The solution circulation flow rate Q1 can be calculated using the following formula:

[0093] Q1 = 3600 × A × vQ 5)

[0094] In Equation 5), Q represents the system's water treatment capacity, in cubic meters per second (m³). 3 / h; v is the fluid velocity, 8–10 m / s; A is the cross-sectional area of ​​the fluid flow in the photoelectro-oxidation unit, in m². 2 .

[0095] In the optimized implementation method, the organic wastewater after degradation by the photoelectric oxidation unit is mixed with alkaline solution to adjust the pH to 7.5-8.5, resulting in alkaline wastewater. Flocculant is added to the alkaline wastewater, and the pollutants in the organic wastewater mix with the flocculant to form flocs, which then precipitate to obtain sludge precipitate and supernatant. The supernatant is collected and enters the next process for treatment, and the sludge precipitate is collected and then concentrated.

[0096] Part of the sludge is returned to the alkaline waste liquid for sludge recirculation. Through the seed crystal growth effect in the sludge sediment and the recycling of flocculants, the cost of reagents can be significantly reduced. The sludge sedimentation recirculation flow rate Q2 can be calculated using the following formula:

[0097] Q2=η×Q 6)

[0098] In Equation 6), Q represents the system's water treatment capacity, in cubic meters per second (m³). 3 / h; η is the reflux coefficient, 3%~5%.

[0099] Example 2

[0100] As per the instruction manual Figure 1 As shown, the present invention also provides a degradation treatment system for organic wastewater, comprising:

[0101] Acidity adjustment unit 1 is used to adjust the pH of organic wastewater to acidic.

[0102] The photoelectro-oxidation unit 2 includes an electrolytic cell 21 and an ultraviolet lamp 22 disposed on the electrolytic cell 21. The feed inlet of the electrolytic cell 21 is connected to the discharge outlet of the acid adjustment unit 1. The electrolytic cell 21 is provided with a plurality of electrode groups.

[0103] Alkalinity adjustment unit 3 is used to adjust the pH of organic wastewater to alkalinity, and the alkali adjustment unit 3 is connected to the electrolytic cell 21;

[0104] The flocculation and sedimentation unit 4 includes a flocculation tank and a sedimentation tank 43. The flocculation tank is connected to the alkali adjustment unit 3, and the sedimentation tank 43 is connected to the flocculation tank.

[0105] In an optimized implementation, the acid-adjusting unit 1 includes a pipeline mixer 11, a sulfuric acid tank 12, an acid-adjusting tank 13, and a stirrer 14. The sulfuric acid tank 12 is connected to the pipeline mixer 11 and is used to supply dilute sulfuric acid into the pipeline mixer 11. Organic wastewater enters the pipeline mixer 11 and mixes with the dilute sulfuric acid. The inlet of the acid-adjusting tank 13 is connected to the outlet of the pipeline mixer 11. The stirrer 14 is installed on the acid-adjusting tank 13 for stirring and mixing the organic wastewater and dilute sulfuric acid. A pH online monitoring instrument 15 is connected to the pipeline between the pipeline mixer 11 and the acid-adjusting tank 13, as well as to the acid-adjusting tank 13, for real-time monitoring of the pH value of the organic wastewater. The acid-adjusting tank 13 is also equipped with a level gauge 16 for monitoring the solution level inside the tank. The inlet of the electrolytic cell 21 is connected to the outlet of the acid-adjusting tank 13.

[0106] Preferably, a wastewater metering pump is installed on the pipeline through which the organic wastewater enters the pipeline mixer to regulate the flow rate of the organic wastewater, and an acid metering pump is installed on the pipeline between the sulfuric acid tank and the pipeline mixer to regulate the flow rate of dilute sulfuric acid.

[0107] Of course, each pipeline of the acid adjustment unit 1 is equipped with a flow meter to monitor the liquid flow rate in each pipeline.

[0108] In some embodiments, both the pipe mixer 11 and the acid adjusting tank 13 are provided with dampers.

[0109] The diameter of the pipe mixer is calculated using the following formula:

[0110] D = (1.27 × Q / v)^0.5 7)

[0111] In Equation 7), Q represents the system's water treatment capacity, in m³. 3 / s; v is the water flow velocity, ranging from 0.8 to 1.2 m / s; 1.27 is the formula coefficient.

[0112] The residence time of organic wastewater and dilute sulfuric acid in the pipeline mixer 11 is 10-20 s. The pipeline mixer 11 includes multiple mixing elements. The pH value of the organic wastewater to be treated is monitored, and the amount of dilute sulfuric acid to be added is calculated based on its flow rate into the pipeline mixer. The organic wastewater and dilute sulfuric acid are initially mixed in the pipeline mixer, and then further mixed in the acid adjustment tank. The online pH monitor 15 is interlocked with the acid metering pump, which monitors the pH value of the mixture in real time and adjusts the power of the acid metering pump accordingly to adjust the pH value of the organic wastewater to 4-5. If the pH value of the mixture is greater than the set range, the amount of dilute sulfuric acid added is increased; if the pH value of the mixture is less than the set range, the amount of dilute sulfuric acid added is decreased. The specific adjustment process is as follows:

[0113] When the feedback signal value of the pH online monitoring instrument 15 is greater than 3.5, the Hertz of the acid metering pump is increased by 5. After a reaction time of 10 seconds, the feedback signal values ​​of the pH online monitoring instrument 15 before and after 10 seconds are compared.

[0114] A. If the feedback signal value decreases, the hertz of the acid metering pump decreases by 1. After a further reaction time of 10 seconds, compare the feedback signal value of the pH online monitoring instrument before and after 10 seconds with the reduction acceleration. If the reduction acceleration decreases (reduction acceleration formula a = (lg10s feedback signal value - lg10s feedback signal value) / 10), the hertz of the acid metering pump continues to decrease by 1 until the reduction acceleration becomes zero. When the reduction acceleration becomes zero, if the pH online monitoring instrument feedback signal value is greater than 3.5, the wastewater metering pump stops, and the acid metering pump operates at the hertz required to ensure the reduction acceleration becomes zero. When the pH online monitoring instrument feedback signal value is 3.5, the wastewater metering pump starts. When the reduction acceleration becomes zero, if the pH online monitoring instrument feedback signal value is less than 3.5, the acid metering pump stops, and the wastewater metering pump continues to supply water until the pH online monitoring instrument feedback signal value is 3.5, at which point the acid metering pump starts and operates at the hertz required to ensure the reduction acceleration becomes zero.

[0115] B. If the feedback signal value increases, the Hertz of the acid metering pump continues to increase by 5 until the feedback signal value decreases, and then proceed according to step A.

[0116] When the pH online monitoring instrument feedback signal value is less than 3.5, the acid metering pump stops, and the wastewater metering pump starts to supply water until the pH online monitoring instrument feedback signal value is greater than 3.5, then the above steps are executed.

[0117] As per the instruction manual Figure 2As shown, the photoelectric oxidation unit 2 also includes a hydrogen peroxide tank 23 and a circulation pump 24. The hydrogen peroxide tank 23 is connected to the electrolytic cell 21. Acidic organic wastewater flows into the electrolytic cell, where hydroxyl radicals generated degrade the organic matter. Electrode groups are arranged sequentially and at intervals within the electrolytic cell 21. Each electrode group includes a first anode, a first cathode, a second anode, and a second cathode arranged sequentially and at intervals. Both the first and second cathodes are carbon-based cathodes. The first anode is a carbon-based anode, and the second anode is an induction iron-based anode. The electrode plates used for each cathode and anode are vertically arranged. The preparation method of each electrode and the arrangement of the electrodes within the electrolytic cell have been described in Example 1 and will not be repeated here. The hydrogen peroxide tank 23 is connected to the electrolytic cell 21 and is used to supply hydrogen peroxide to the electrolytic cell 21. The organic wastewater is adjusted to acidity in the acidification unit 1 and then sent to the electrolytic cell 21. The hydroxyl radicals generated in the electrolytic cell 21 can degrade the organic matter in the organic wastewater, thereby purifying the organic wastewater. The electrolytic cell 21 is equipped with a circulation pipeline for circulating the solution in the electrolytic cell 21. The circulation pump 24 is located on the circulation pipeline, and the ultraviolet lamp 22 is located on the circulation pipeline.

[0118] Preferably, the electrolytic cell is also connected to an online iron ion monitor and an online ORP monitor to adjust the anode voltage and current as well as the amount of hydrogen peroxide added.

[0119] Preferably, the electrolytic cell is connected to two circulation pipelines, each controlled independently, with one in operation and one on standby. The circulation pump primarily enhances the mass transfer effect of the photoelectro-oxidation unit and reduces the concentration gradient within the electrolytic cell. The circulation pump flow rate is detailed in Formula 5). The ultraviolet lamp is located at the outlet of the circulation pump, with a wavelength of 200–300 nm, preferably in a one-in-one-on-standby configuration. Valves are installed on the circulation pipelines, and the ultraviolet lamps have inspection ports. By switching the valves, sludge adhering to the ultraviolet lamps can be cleaned promptly. The ultraviolet lamp, acting on the mixed solution in the circulation pipeline, can effectively promote Fe… 2+ And the regeneration of hydroxyl radicals.

[0120] The photoelectro-oxidation unit 2 also includes a DC power supply 26, which is connected to the electrode plates in the electrode assembly. A level gauge is also connected to the electrolytic cell to monitor the solution level within the cell. Flow meters and valves are installed on each pipeline of the photoelectro-oxidation unit to regulate the flow rate.

[0121] The alkali adjustment unit 3 includes a neutralization tank 31. Organic wastewater degraded by the photoelectric oxidation unit enters the neutralization tank 31. The neutralization tank 31 is equipped with a stirrer and connected to an alkali tank 32. An alkali addition pipeline connects the neutralization tank 31 and the alkali tank 32. An online pH monitor is also connected to the neutralization tank 31 to monitor the acidity and alkalinity of the solution. This online pH monitor is interlocked with an alkali metering pump on the alkali addition pipeline. The pH of the organic wastewater in the neutralization tank is adjusted to 7.5–8.5. The specific adjustment process is as follows:

[0122] (1) When the pH online monitoring instrument feedback signal value is less than 8.5, the Hertz of the alkali metering pump is increased by 5. After a reaction time of 10 s, the pH online monitoring instrument feedback signal value is compared before and after 10 s.

[0123] A. If the feedback signal value increases, the Hertz of the alkali metering pump decreases by 1. After a further 10 seconds of reaction time, compare the pH online monitoring signal value and the acceleration before and after 10 seconds. If the acceleration decreases (acceleration reduction formula a = (lg feedback signal value before 10 seconds - lg feedback signal value after 10 seconds) / 10), the Hertz of the alkali metering pump continues to decrease by 1 until the acceleration decreases to zero. When the acceleration decreases to zero, if the pH online monitoring signal value is less than 8.5, the neutralization tank stops receiving organic wastewater, and the alkali metering pump operates at the Hertz required to ensure the acceleration decreases to zero. When the pH online monitoring signal value is 8.5, the inlet pump at the neutralization tank feed end is started. When the acceleration decreases to zero, if the pH online monitoring signal value is less than 8.5, the alkali metering pump stops, and the inlet pump continues to supply water until the pH online monitoring signal value is 8.5, at which point the alkali metering pump is started again and operates at the Hertz required to ensure the acceleration decreases to zero.

[0124] B. If the feedback signal value remains unchanged, continue to increase the Hertz of the alkali metering pump by 5 until the feedback signal value decreases, and then proceed according to step A.

[0125] (2) When the pH online monitoring instrument feedback signal value is greater than 8.5, the alkali metering pump stops, and the water inlet pump continues to supply water until the pH online monitoring instrument feedback signal value is less than 8.5, then proceed with step (1).

[0126] Preferably, the alkali adjustment unit 3 further includes a buffer tank 33, which is connected to the neutralization tank 31 to facilitate thorough and uniform mixing of the alkali solution and the organic wastewater. To facilitate the precipitation of flocs in the organic wastewater, some sludge is returned to the buffer tank 33. Utilizing the seed crystal growth effect in the precipitate, precipitation and sedimentation can be promoted, reducing reagent costs.

[0127] The flocculation and sedimentation unit 4 includes an integrated flocculation and sedimentation tank, as shown in the attached instruction manual. Figure 3As shown, the system includes a flocculation tank and a sedimentation tank 43. The flocculation tank comprises a first flocculation tank 41 and a second flocculation tank 42. The first flocculation tank 41 is connected to a buffer tank 33, and the inlet of the second flocculation tank 42 is connected to the outlet of the first flocculation tank 41. The first flocculation tank 41 is connected to a PAC tank 44 (PAC: polyaluminum chloride) for preliminary sedimentation of pollutants in the organic wastewater. The second flocculation tank is connected to a PAM tank 45 (PAM: polyacrylamide) for further sedimentation of organic matter in the organic wastewater. The sedimentation tank 43 is connected to the second flocculation tank 42. Pollutants in the organic wastewater mix with flocculant in the flocculation tank to form flocs, which are then sent to the sedimentation tank 43 for sedimentation, resulting in sludge sediment and supernatant. The sludge sediment can be collected in a sludge thickening tank for further treatment, and some of the sludge sediment can be returned to the buffer tank. The supernatant overflows to the next process. The sediment in the buffer tank, the first flocculation tank, and the second flocculation tank can also be collected in the sludge thickening tank for further treatment. The sludge sediment is returned to the buffer tank 33 through a sludge return pipe, effectively utilizing the unreacted flocculant and significantly reducing reagent costs. A sludge return pump is installed on the sludge return pipe, and the flow rate Q2 of the sludge return pump can be calculated using the following formula:

[0128] Q2=η×Q 8)

[0129] In Equation 8), Q represents the system's water treatment capacity, in cubic meters per second (m³). 3 / h; η is the reflux coefficient, which takes a value of 3%~5%.

[0130] Organic wastewater undergoes flocculation and sedimentation in a flocculation sedimentation tank using floc sight glass technology. This involves establishing an image recognition model of floc particle size and density to intelligently adjust the dosage, significantly reducing both chemical and labor costs. The specific method is as follows:

[0131] 1. Establish the particle size and density per unit volume of floc under different PAC and PAM conditions, and build a generalized model;

[0132] 2. Based on actual water quality conditions, continuously optimize model parameters through machine learning;

[0133] 3. By utilizing the characteristics of floc captured by an underwater high-definition camera, the system automatically feeds back the operating status through a digital model, adjusts the frequency of PAC and PAM dosing pumps, significantly improves the quality of the effluent, and can save more than 30% of the dosage.

[0134] Preferably, the sedimentation tank 43 is an inclined tube sedimentation tank, and the sedimentation tank 43 is equipped with a backwashing device, which includes a high-pressure pulse blower 46 and a backwashing duct 47. The backwashing method adopts an intermittent cross-cleaning mode. The air volume Q3 of the high-pressure pulse blower can be calculated according to the following formula:

[0135] Q3 = q × L × b 9)

[0136] In Equation 9), q represents the backwash intensity, ranging from 20 to 80 μm. 3 / (m 2 *h); L is the length of the inclined tube sedimentation tank; b is the spacing of the backwash ducts, ranging from 1 to 2 m.

[0137] Those skilled in the art will understand that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the invention. Although embodiments of the invention have been described, it should be understood that the invention is not limited to these embodiments, and those skilled in the art can make changes and modifications within the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for degrading and treating organic wastewater, characterized in that, Includes the following steps: Adjust the pH of the organic wastewater to acidic; Acidic organic wastewater and hydrogen peroxide are added to the photoelectric oxidation unit. The hydrogen peroxide reacts with the electrode assembly in the unit via an electro-Fenton reaction to generate hydroxyl radicals that degrade the acidic organic wastewater. Through electrochemical reaction and ultraviolet light excitation, the Fe in the solution is activated. 2+ The photoelectric oxidation unit regenerates hydroxyl radicals. Multiple electrode groups are used, each including a first anode, a second anode, and a carbon-based cathode. The first and second anodes are arranged alternately. The first anode is a carbon-based anode, and the second anode is an inductive iron-based anode. The electrode groups are arranged in the order of carbon-based anode, carbon-based cathode, inductive iron-based anode, and carbon-based cathode, with a spacing of 1–2 mm between adjacent electrodes. The iron ion concentration in the photoelectric oxidation unit is 20 mg / L–40 mg / L. The carbon-based anode and carbon-based cathode form an electric field through an external power source. Under the influence of the electric field, the inductive iron-based anode spontaneously precipitates ferrous ions without the need for an external power source. The pH of the wastewater after photoelectro-oxidation treatment was adjusted to alkaline, and flocculant was added to the alkaline wastewater to obtain sludge sediment and supernatant. The supernatant was then subjected to further treatment. The formula for calculating the number n of the induction iron-based anodes is as follows: n=Q×C×t / (A×h×ρ / 1000) / 1000 Q represents the system's water processing capacity, in cubic meters (m³). 3 / d; C is the system iron ion concentration of 20–40 mg / L; A is the area of ​​the inductive iron-based anode, taken as 1–2 m². 2 h represents the thickness of the induction iron-based anode, ranging from 4 to 10 mm; ρ represents the density of the induction iron-based anode, ranging from 7 to 7.8 g / cm³. 3 t represents the replacement time of the induction iron-based anode, which is 300–600 days. The method for preparing the carbon-based anode is as follows: 1) Add additives to carbon-based raw material powder, stir and mix, and extrude the mixture to obtain carbon-based products; 2) The carbon-based product is roasted to carbonize the additives; 3) The calcined carbon-based product is impregnated with a liquid impregnating agent, which penetrates into the electrode pores of the carbon-based product; 4) The impregnated carbon-based products are then subjected to a second firing to carbonize the impregnating agent; 5) The carbon-based product after secondary roasting is subjected to high-temperature calcination at a temperature not lower than 2300℃ to obtain a carbon-based anode.

2. The method for degrading and treating organic wastewater according to claim 1, characterized in that, Step 1) of extruding the mixture specifically includes the following steps: Cooling: Remove the volatile components from the mixture, then lower the temperature of the mixture to 90-120 ℃ and keep it warm for 20-30 minutes; Loading: Compact the cooled mixture at 4-10 MPa for 2-3 min; Pre-compression: Compact the mixture at 20-25 MPa for 3-5 min, while simultaneously applying a vacuum. Extrusion: The pre-compressed mixture is extruded at 5-15 MPa, then sheared and cooled to obtain carbon-based products.

3. The method for degrading and treating organic wastewater according to claim 1, characterized in that, Step 3) of the impregnation of carbon-based products specifically includes the following steps: Clean the surface of the calcined carbon-based product and preheat it to 260-380 ℃, then keep it at that temperature for 6-10 hours. The preheated carbon-based product is placed into an impregnation tank, the tank is evacuated, and then an impregnation agent is injected into the impregnation tank. Pressurize the tank to 1.2-1.5 MPa, immerse for 3-4 hours, and then cool to complete the impregnation of carbon-based products.

4. The method for degrading and treating organic wastewater according to claim 1, characterized in that, The carbon-based cathode is prepared by placing carbon-based raw materials in a high-temperature furnace, evacuating the furnace or introducing inert gas, heating it to 2200-2500 ℃ at a heating rate of 100-300 ℃ / h, holding it at that temperature for a period of time, and then cooling it to obtain the carbon-based cathode.

5. The method for degrading and treating organic wastewater according to claim 1, characterized in that, Monitor the measured value of ORP in the photoelectro-oxidation unit. If the measured value of ORP is less than the set value of ORP, increase the amount of hydrogen peroxide added until the measured value of ORP equals the set value of ORP; if the measured value of ORP is greater than the set value of ORP, decrease the amount of hydrogen peroxide added until the measured value of ORP equals the set value of ORP.

6. The method for degrading and treating organic wastewater according to claim 1, characterized in that, The iron ion concentration in the photoelectric oxidation unit is 20 mg / L to 40 mg / L. If the detected iron ion concentration is less than 20 mg / L, the anode voltage is increased; if the detected iron ion concentration is greater than 40 mg / L, the anode voltage is decreased.

7. The method for degrading and treating organic wastewater according to claim 1, characterized in that, The alkaline organic wastewater is treated with flocculant and then precipitated. The precipitate is then backwashed using a backwashing device at an intensity of 20-80 m. 3 / (m 2 *h); A portion of the sludge is precipitated and returned to the alkaline wastewater.

8. A system applicable to the degradation treatment method of organic wastewater according to any one of claims 1-7, characterized in that, include: The pH adjustment unit is used to adjust the pH of organic wastewater to acidic. The photoelectro-oxidation unit includes an electrolytic cell and an ultraviolet lamp mounted on the electrolytic cell. The feed inlet of the electrolytic cell is connected to the discharge outlet of the acid adjustment unit. Several electrode groups are provided inside the electrolytic cell. An alkali adjustment unit is used to adjust the pH of organic wastewater to alkaline, and the alkali adjustment unit is connected to the electrolytic cell; The flocculation and sedimentation unit includes a flocculation tank and a sedimentation tank. The flocculation tank is connected to the alkali adjustment unit, and the sedimentation tank is connected to the flocculation tank.

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