Degradation treatment method and system for organic wastewater

Abstract

The invention relates to a degradation treatment method and system for organic wastewater. The method comprises the following steps: adjusting the pH of the organic wastewater to be acidic; the method comprises the following steps: adding acidic organic wastewater and hydrogen peroxide into a photoelectric oxidation unit, carrying out electro-Fenton reaction on the hydrogen peroxide and an electrode group in the photoelectric oxidation unit to generate hydroxyl radicals for degrading the acidic organic wastewater, and regenerating Fe < 2 + > and the hydroxyl radicals in the solution through electrochemical reaction and ultraviolet excitation conjugation; adjusting the pH value of the wastewater subjected to the photoelectric oxidation treatment to be alkaline, adding a flocculating agent into the alkaline wastewater to obtain sludge precipitate and supernate, and performing subsequent treatment on the supernate. The regeneration rate of ferrous ions and hydroxyl radicals is improved by adopting a catalyst full-amount efficient utilization mode of natural precipitation of an induction iron electrode, electrochemical and ultraviolet light reduction and trace iron sludge precipitation, so that the degradation of organic matters in the organic wastewater is promoted.

Description

Technical Field

[0001] The invention relates to the technical field of organic wastewater degradation, and in particular to a method and system for degradation treatment of organic wastewater. Background Art

[0002] The resource utilization of wastewater has become a hot topic in the current environmental protection industry. Wastewater treatment is a process that removes pollutants from wastewater or sewage and converts it into water circulation or direct reuse of wastewater with minimal impact on the environment. Its purpose is to reduce pollutants in wastewater to an acceptable level, ensuring that the water can be safely discharged back into the environment, or used for other non-drinking purposes, such as industry, irrigation, etc. In the current treatment of organic wastewater in the industry, physical or biochemical methods are usually used to remove organic matter, but it is difficult to achieve the purpose of resource utilization. Therefore, there is an urgent need for a degradation treatment method and system for organic wastewater to solve the difficult-to-degrade organic matter in the current water environment field and achieve water environment safety and sustainable development. Summary of the invention

[0003] In order to solve the above problems, on the one hand, the present invention provides a method for degradation treatment of organic wastewater, comprising the following steps:

[0004] Adjust the pH of 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 group in the photoelectric oxidation unit to generate hydroxyl radicals for degrading acidic organic wastewater. The Fe 2+ and hydroxyl radical regeneration;

[0006] The pH of the wastewater after the photoelectric oxidation treatment is adjusted to alkaline, and a flocculant is added to the alkaline wastewater to obtain sludge precipitation and supernatant, and the supernatant is subsequently treated.

[0007] Furthermore, the electrode groups are multiple groups, each of which includes a first anode, a second anode and a carbon-based cathode, the first anode and the second anode are arranged at intervals, the first anode is a carbon-based anode, the second anode is an induction iron-based anode, and the spacing between each adjacent electrode piece is 1 to 2 mm.

[0008] Furthermore, the preparation method of the carbon-based anode is:

[0009] 1) Adding additives to the carbon-based raw material powder, stirring and mixing, and extruding the mixture to obtain a carbon-based product;

[0010] 2) calcining the carbon-based article to carbonize the additive;

[0011] 3) impregnating the calcined carbon-based product with an impregnant, wherein the impregnant penetrates into the electrode pores of the carbon-based product;

[0012] 4) performing secondary calcination on the impregnated carbon-based product to carbonize the impregnant;

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

[0014] Furthermore, in step 1, extruding the mixture specifically comprises the following steps:

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

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

[0017] Pre-pressing: compact the mixture at 20-25 MPa for 3-5 minutes, and evacuate the mixture during compaction;

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

[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°C for 6-10 hours;

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

[0022] The tank is pressurized to 1.2-1.5 MPa, immersed for 3-4 hours, and cooled to complete the impregnation of the carbon-based product.

[0023] Furthermore, the preparation method of the carbon-based cathode is: placing the carbon-based raw material in a high-temperature furnace, evacuating the high-temperature furnace or passing an inert gas, heating it to 2200-2500°C at a heating rate of 100-300°C / h, keeping it warm for a period of time, and then cooling it to obtain the carbon-based cathode.

[0024] Further, the ORP measured value in the photoelectric oxidation unit is monitored. If the ORP measured value is less than the ORP set value, the amount of hydrogen peroxide added is increased until the ORP measured value is equal to the ORP set value; if the ORP measured value is greater than the ORP set value, the amount of hydrogen peroxide added is reduced until the ORP measured value is equal to the ORP set value.

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

[0026] Furthermore, the alkaline organic wastewater is precipitated after adding a flocculant, and the precipitate is backwashed by a backwashing device, and the backwashing intensity is 20 to 80 m 3 / (m 2 *h); returning part of the sludge sediment to the alkaline wastewater.

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

[0028] Acid adjustment unit, used to adjust the pH of organic wastewater to acidic;

[0029] The photoelectric oxidation unit comprises an electrolytic cell and an ultraviolet lamp arranged on the electrolytic cell, wherein the feed port of the electrolytic cell is connected to the discharge port of the acid conditioning unit, and a plurality of electrode groups are arranged in the electrolytic cell;

[0030] An alkali adjustment unit, used for adjusting the pH of the organic wastewater to alkaline, the alkali adjustment unit being connected to the electrolytic cell;

[0031] The flocculation and sedimentation unit comprises 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] Due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0033] 1) The method for degradation and treatment of organic wastewater provided by the present invention comprises an electrode group in a photoelectric oxidation unit adopting a combination of a carbon-based anode, a carbon-based cathode, an induction iron-based anode and a carbon-based cathode. An ultraviolet lamp is also provided in the photoelectric oxidation unit. The natural precipitation of the induction iron electrode, electrochemical and ultraviolet light reduction, and a catalyst full-quantity efficient utilization mode of trace iron mud precipitation are adopted to improve the regeneration rate of ferrous ions and hydroxyl radicals. The strong quenching effect of complex components of wastewater on traditional free radicals is broken through the synergistic mechanism of photoelectric coupling chemical oxidation. The circulation efficiency of the catalyst and the generation rate of free radicals are improved through the radiation effect of ultraviolet light, thereby promoting the degradation of organic matter in organic wastewater.

[0034] 2) The degradation treatment method for organic wastewater provided by the present invention prepares carbon-based anodes and carbon-based cathodes by different methods to meet different electrode usage requirements, thereby realizing 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 the operating cost by 40%, and reduces the sludge production by 60% through the interlocking control of the online monitoring of iron ions and the DC power supply.

[0036] 4) The degradation treatment method for organic wastewater provided by the present invention realizes rapid sludge precipitation and effluent stability in the flocculation and sedimentation unit of the organic wastewater through seeding and backwashing, which greatly reduces the cost of chemicals and labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

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

[0039] Figure 2 A schematic diagram of the structure of a 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 structure of a 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-sulphuric acid tank; 13-acid adjustment tank; 14-agitator; 15-pH online monitor; 16-liquid level gauge; 2-photoelectric oxidation unit; 21-electrolyzer; 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 liquid 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 fan; 47-backwash air duct. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In the drawings, the size and relative size of some parts may be enlarged for clarity.

[0043] In the description of the present invention, unless otherwise clearly stipulated and limited, the terms "connection" and "connected" should be interpreted in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] In the description of the present invention, terms such as "up", "down", "left", "right", "front", "back", etc., and the orientation or position relationship are based on the orientation or position relationship shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0045] In addition, in the description of the present invention, the terms "first" and "second" are only used to distinguish in the description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In addition, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0046] Example 1

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

[0048] Adjust the pH of 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 group 25 in the photoelectric oxidation unit 2 to generate hydroxyl radicals for degrading acidic organic wastewater. The Fe 2+ and hydroxyl radical regeneration;

[0050] The pH of the wastewater after the photoelectric oxidation treatment is adjusted to alkaline, and a flocculant is added to the alkaline wastewater to obtain sludge precipitation and supernatant, and the supernatant is subsequently treated.

[0051] In an optimized implementation mode, the electrode group 25 is a plurality of groups, each of which includes a first anode, a second anode and a carbon-based cathode, the first anode and the second anode are arranged at intervals, that is, a carbon-based cathode is arranged between the first anode and the second anode, the first anode is a carbon-based anode, the carbon-based anode is energized, the second anode is an induction iron-based anode, the induction iron-based anode does not need to be energized, and the spacing between each adjacent pole piece is 1 to 2 mm. In this embodiment, each electrode group 25 includes a carbon-based anode, an induction iron-based anode and two carbon-based cathodes, wherein the electrode sheets are arranged in the order of a carbon-based anode, a carbon-based cathode, an induction carbon-based anode and a carbon-based cathode, and the spacing between adjacent pole pieces is 1 to 2 mm, such as the spacing between an induction iron-based anode and an adjacent carbon-based cathode is 1 to 2 mm, the carbon-based anode and the carbon-based cathode form an electric field through an external power supply, and the induction iron-based anode spontaneously precipitates ferrous ions under the action of the electric field without the need for an external power supply.

[0052] Preferably, the pH of the organic wastewater is adjusted to 4-5 to obtain acidic organic wastewater, and then the acidic organic wastewater is passed into a photoelectric oxidation unit, hydrogen peroxide is passed into the photoelectric oxidation unit, and an electrolytic cell is formed with an electrode group, and the induction iron-based anode oxidation precipitates Fe 2+ , Fe 2+ The Fenton reaction with hydrogen peroxide generates hydroxyl radicals (·OH), and the reaction formula is shown in Formula 1). Hydroxyl radicals have strong oxidizing properties and can oxidize complex, difficult-to-biodegrade organic matter, thereby effectively degrading organic wastewater. The degraded organic wastewater is adjusted to alkaline, and then a flocculant is added. The pollutants in the organic wastewater are mixed with the flocculant to form alum flocs, which are then precipitated to obtain precipitated sludge and supernatant. The supernatant can enter the next treatment process, and the precipitated sludge can be concentrated and collected.

[0053] Fe 2+ +H2O2→Fe 3+ + OH+OH - 1)

[0054] Fe generated by electro-Fenton reaction 3+ , is reduced to Fe by the cathode 2+ , and then react with hydrogen peroxide to obtain hydroxyl radicals, which induce the iron-based anode oxidation to dissolve Fe 2+ The rate is much greater than that of Fe 3+ The reduction rate of Fe 2+ Reaction with hydrogen peroxide will generate more Fe 3+ , and then generate iron mud, which needs to be Fe 2+ and the regeneration of hydroxyl radicals. UV light and Fe 2+ Both can catalyze the decomposition of H2O2 to produce ·OH, and the two have a synergistic effect on the catalytic decomposition of H2O2 to produce ·OH. Because some hydroxyl complexes of iron at pH 3-5, Fe3+ Fe(OH) 2+ It exists in the form of photosensitive reaction, has good light absorption performance, and can generate more OH by photosensitization reaction. The reaction formula is shown in formula 2). At the same time, it can enhance the Fe 3+ The reduction of Fe 2+ This helps maintain Fe 2+ concentration to ensure that the Fenton reaction continues, thereby reducing Fe 2+ Dosage to maintain a high H2O2 utilization rate.

[0055] Fe(OH) 2+ +hv→Fe 2+ +·OH 2)

[0056] In the above formula, the reaction condition is light (hv), where h represents Planck's constant and v represents the frequency of light. 2+ As well as the regeneration of hydroxyl radicals, reducing the induction iron-based anode and hydrogen peroxide consumption, the dual anode form consisting of an iron anode and a carbon anode can form a more uniform current distribution in the electrolytic cell.

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

[0058] In an optimized implementation mode, the preparation method of the carbon-based anode is as follows:

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

[0060] Specifically, the carbon-based raw material is biostraw, graphite, etc., the additive is at least one of coal tar, asphalt, and resin, and the amount of the 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 crushed into powder, sieved, and a powder with a particle size of 0.5 to 20 mm is obtained, and then the powder is ground into fine powder, and the particle size of the fine powder is less than 0.075 mm. Additives are added to the carbon-based fine powder and stirred and mixed, wherein dry mixing is 20 to 35 minutes and wet mixing is 40 to 55 minutes to obtain a uniformly dispersed mixture. The mixture is placed in a special mold for rough molding, and the roughly molded mixture is extruded to obtain a carbon-based product.

[0061] 2) The carbon-based article is calcined to carbonize the additives.

[0062] Specifically, the formed carbon-based product is placed in a heating furnace and calcined under the protection of fillers at a calcination temperature of 1050-1360°C for 320-480 hours to carbonize the additives in the carbon-based product. The mixed material can be calcined to increase its mechanical strength, reduce its resistivity, and improve its thermal stability and chemical stability.

[0063] The calcination temperature is preferably 1250°C.

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

[0065] Specifically, the calcined carbon-based product is impregnated with a liquid impregnant, so that the impregnant penetrates into the electrode pores of the product to reduce the porosity, increase the bulk density and mechanical strength, and improve the electrical conductivity and thermal conductivity of the product. The liquid impregnant is preferably asphalt.

[0066] 4) The impregnated carbon-based product is subjected to secondary calcination to carbonize the impregnant.

[0067] Specifically, the impregnated carbon-based product is treated again and subjected to secondary calcination at a temperature of 700 to 800° C. for 120 to 280 hours, so that the asphalt impregnated in the pores of the calcined product is further carbonized.

[0068] 5) The carbon-based product after the secondary calcination is subjected to high-temperature calcination at a temperature not lower than 2300° C. 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 calcination temperature of not less than 2300°C, so that the amorphous disordered carbon is converted into a three-dimensional ordered graphite crystal structure. Finally, mechanical processing is performed to cut and grind the calcined product to a set shape and size to obtain a carbon-based anode.

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

[0071] In the optimized implementation mode, in step 1, the roughly formed mixture is extruded in a screw extruder or a horizontal hydraulic extruder, which specifically includes the following steps:

[0072] Cooling material: remove the volatile components in the mixture by using disc cooling material, cylinder cooling material, kneading cooling material and other methods, then reduce the temperature of the mixture to 90-120℃ and keep it warm for 20-30min; this can increase the cohesiveness of the mixture and make the paste block uniform, which is conducive to molding;

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

[0074] Pre-pressing: compact the mixture at 20-25 MPa for 3-5 minutes, and evacuate the mixture during compaction;

[0075] Extrusion: The pre-pressed mixture is extruded at 5-15 MPa, then sheared into the required size, and placed in a cooling water tank for cooling to obtain a carbon-based product.

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

[0077] Clean the surface of the calcined carbon-based product and preheat the carbon-based product to 260-380°C for 6-10 hours;

[0078] The preheated carbon-based product is placed in an impregnation tank, and 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, and the asphalt temperature is 180-200°C.

[0079] The pressure inside the tank is increased to 1.2-1.5MPa, and the tank is impregnated for 3-4 hours. The asphalt is returned and the inside and outside of the tank are cooled. The impregnation of the carbon-based product is completed.

[0080] In an optimized implementation method, the carbon-based cathode is prepared by placing the carbon-based raw material in a high-temperature furnace, evacuating the high-temperature furnace or introducing an inert gas, heating the furnace to 2200-2500°C at a heating rate of 100-300°C / h, keeping the temperature for a period of time, and then cooling the furnace to obtain the carbon-based cathode. The carbon-based cathode prepared by the above method has a volume density of 0.20 g / cm 3 ~0.10g / cm 3 , resistivity 10~20uQ.m, carbon content greater than 99.9%.

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

[0082] The carbon-based anode and carbon-based cathode prepared by the above method in the present application, the carbon-based cathode acts as an electron accepting substrate, reducing ferric iron to ferrous iron, and reducing hydrogen ions to hydrogen, and the carbon-based cathode has a good reduction effect; the carbon-based anode acts as an electron providing substrate, converting organic matter into carbon dioxide, and oxidizing oxygen ions to oxygen. The carbon-based anode and the carbon-based cathode form an electric field through an external power supply, and the induction iron-based anode spontaneously precipitates ferrous ions under the action of the electric field without the need for an external power supply. The induction iron-based anode provides ferrous ions to the system, and the carbon-based cathode reduces ferric ions to ferrous ions.

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

[0084] The electrolytic cell of the photoelectric oxidation unit adopts a double-anode monopolar coupled bipolar combined electrolytic cell, wherein the electrode group adopts a cross-combination of a carbon-based anode, a carbon-based cathode, an induction iron-based anode, and a carbon-based cathode. The calculation formula of the number of induction iron-based anodes n is as follows:

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

[0086] In formula 3), Q is the water volume treated by the system, unit is m 3 / d; C is the system iron ion 20-40 mg / L; A is the induction iron-based anode area, 1-2 m 2 ; h is the thickness of the induction iron-based anode, which is 4 to 10 mm; ρ is the density of the induction iron-based anode, which is 7 to 7.8 g / cm 3 ; t is the replacement time of the induction iron-based anode, which is 300 to 600 days.

[0087] The distance between each adjacent two 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, and the operating voltage is 3-4 V. The carbon-based anode, carbon-based cathode, and induction iron-based anode are connected to a DC power supply, and the current I0 of the DC power supply is calculated as follows:

[0088] I0=I2×A2×n+C×V×F / t / 28×A1×n×10000 4)

[0089] In formula 4), I2 is the anode current density, ranging from 1 to 5 A / m 2 ; A2 is the anode area, unit: m 2 , C is the mass concentration of iron ions, ranging from 20 to 40 mg / L; A1 is the area of ​​the inductive iron-based anode, in m 2 ; t is the hydraulic retention time, unit is s; F is the Faraday constant, which is 96487C / mol; V is the volume of the reaction zone, unit is L; n is the number of induction iron-based anodes.

[0090] The implementation method is optimized. During the reaction process, the iron ions and ORP (full name is Oxidation-Reduction Potential) in the photoelectric oxidation unit are monitored online, and the anode voltage and current and the amount of hydrogen peroxide added are adjusted intelligently through PID.

[0091] Monitor the ORP measured value in the photoelectric oxidation unit. If the ORP measured value is less than the ORP set value, increase the amount of hydrogen peroxide added until the ORP measured value is equal to the ORP set value; if the ORP measured value is greater than the ORP set value, reduce the amount of hydrogen peroxide added until the ORP measured value is equal to the ORP set value.

[0092] In one embodiment, the ORP setting value is 100; when the ORP measured value is less than 100, the Hz of the hydrogen peroxide dosing pump is increased by 5, and after a reaction time of 10 seconds, the ORP measured values ​​before and after 10 seconds are compared. If the ORP measured value is still less than 100, the Hz of the hydrogen peroxide dosing pump is continued to increase until the ORP measured value is 100. When the ORP measured value is greater than 100, the Hz of the hydrogen peroxide dosing pump is reduced by 5. After a reaction time of 10 seconds, the ORP measured values ​​before and after 10 seconds are compared. If the ORP measured value is still greater than 100, the Hz of the hydrogen peroxide dosing pump is continued to decrease until the ORP measured value is 100.

[0093] In one embodiment, the ion concentration of iron ions in the photoelectric oxidation unit is 20 mg / L to 40 mg / L. If the ion concentration of iron ions is detected to be less than 20 mg / L, the anode voltage is increased. If the ion concentration of iron ions is detected to be greater than 40 mg / L, the anode voltage is reduced.

[0094] In an optimized implementation mode, the photoelectric oxidation unit is provided with a circulation pipeline for circulating the mixed solution in the electrolytic cell, and the ultraviolet lamp is arranged on the circulation pipeline. The solution circulation flow Q1 can be calculated according to the following formula:

[0095] Q1=3600×A×vQ 5)

[0096] In formula 5), ​​Q is the water volume treated by the system, unit is m 3 / h; v is the fluid velocity 8-10m / s; A is the cross-sectional area of ​​the fluid flow in the photoelectric oxidation unit, unit m 2 .

[0097] An optimized implementation method is to add alkali solution to the organic wastewater after degradation by the photoelectric oxidation unit, and adjust the pH to 7.5-8.5 to obtain alkaline wastewater. Flocculant is added to the alkaline wastewater, and the pollutants in the organic wastewater are mixed with the flocculant to form alum flocs, which are then precipitated to obtain sludge precipitate and supernatant. The supernatant is collected and entered into the next process for treatment, and the sludge precipitate is collected and then concentrated.

[0098] Part of the sludge sediment is returned to the alkaline waste liquid for sludge reflux. Through the crystal seed value-added effect and flocculant recycling in the sludge sedimentation, the cost of reagents can be greatly reduced. The sludge sedimentation reflux flow rate Q2 can be calculated according to the following formula:

[0099] Q2=η×Q6)

[0100] In formula 6), Q is the water volume treated by the system, in m 3 / h; η is the reflux coefficient, 3% to 5%.

[0101] Example 2

[0102] As the instruction manual Figure 1 As shown, the present invention also provides a degradation treatment system for organic wastewater, comprising:

[0103] Acid adjustment unit 1, used to adjust the pH of organic wastewater to acidic;

[0104] The photoelectric oxidation unit 2 includes an electrolytic cell 21 and an ultraviolet lamp 22 disposed on the electrolytic cell 21. The feed port of the electrolytic cell 21 is connected to the discharge port of the acid conditioning unit 1. The electrolytic cell 21 is provided with a plurality of electrode groups.

[0105] An alkali adjustment unit 3, used for adjusting the pH of the organic wastewater to alkaline, the alkali adjustment unit 3 is connected to the electrolytic cell 21;

[0106] The flocculation and sedimentation unit 4 comprises 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.

[0107] Optimized implementation mode, the acid adjustment unit 1 includes a pipeline mixer 11, a sulfuric acid tank 12, an acid adjustment tank 13 and an agitator 14, the sulfuric acid tank 12 is connected to the pipeline mixer 11, and is used to provide dilute sulfuric acid to the pipeline mixer 11, the organic wastewater enters the pipeline mixer 11, and is mixed with the dilute sulfuric acid, the feed port of the acid adjustment tank 13 is connected to the discharge port of the pipeline mixer 11, and the agitator 14 is arranged on the acid adjustment tank 13, and is used to stir and mix the organic wastewater and the dilute sulfuric acid. The pipeline between the pipeline mixer 11 and the acid adjustment tank 13 and the acid adjustment tank 13 are connected to a pH online monitor 15 for real-time monitoring of the pH value of the organic wastewater. The acid adjustment tank 13 is also provided with a liquid level meter 16 for monitoring the liquid level of the solution in the tank. The feed port of the electrolytic cell 21 is connected to the discharge port of the acid adjustment tank 13.

[0108] Preferably, a wastewater metering pump is provided on the pipeline through which the organic wastewater enters the pipeline mixer to adjust the flow of the organic wastewater, and an acid metering pump is provided on the pipeline between the sulfuric acid tank and the pipeline mixer to adjust the flow of dilute sulfuric acid.

[0109] Of course, each pipeline of the acid conditioning unit 1 is provided with a flow meter for monitoring the liquid flow in each pipeline.

[0110] In some embodiments, the pipeline mixer 11 and the acid adjustment tank 13 are both provided with dampers.

[0111] The diameter of the pipeline mixer is calculated according to the following formula:

[0112] D=(1.27×Q / v)^0.5 7)

[0113] In formula 7), Q is the amount of water treated by the system, m 3 / s; v is the water flow velocity, ranging from 0.8 to 1.2 m / s; 1.27 is the formula coefficient.

[0114] The residence time of the organic wastewater and dilute sulfuric acid in the pipeline mixer 11 is 10 to 20 seconds, and the pipeline mixer 11 includes a multi-section mixing element. The pH value of the organic wastewater to be treated is monitored, and the amount of dilute sulfuric acid added is calculated according to the flow rate of the organic wastewater flowing into the pipeline mixer. The organic wastewater and dilute sulfuric acid are preliminarily mixed in the pipeline mixer, and then enter the acid adjustment tank for further mixing. The pH online monitor 15 is interlocked with the acid addition metering pump to monitor the pH value of the mixed liquid in real time and feedback to adjust the power of the acid addition metering pump to adjust the pH value of the organic wastewater to 4 to 5. If the pH value of the mixed liquid is greater than the set range, the amount of dilute sulfuric acid added is increased. If the pH value of the mixed liquid is less than the set range, the amount of dilute sulfuric acid added is reduced. The specific adjustment process is as follows:

[0115] When the feedback signal value of the pH online monitor 15 is greater than 3.5, the hertz of the acid metering pump is increased by 5. After the reaction time is 10 seconds, the feedback signal values ​​of the pH online monitor 15 before and after 10 seconds are compared.

[0116] A. If the feedback signal value decreases, the hertz of the acid metering pump decreases by 1. After the reaction time continues for 10s, compare the feedback signal value of the pH online monitor and the reduction acceleration before and after 10s. If the reduction acceleration becomes smaller (the reduction acceleration formula a=(lg10s before feedback signal value-lg10s after 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 feedback signal value of the pH online monitor is greater than 3.5, the wastewater metering pump stops, and the acid metering pump operates in accordance with the hertz that ensures the reduction acceleration becomes zero. When the feedback signal value of the pH online monitor is 3.5, the wastewater metering pump is started. When the reduction acceleration becomes zero, if the feedback signal value of the pH online monitor is less than 3.5, the acid metering pump stops, and the wastewater metering pump continues to take in water until the feedback signal value of the pH online monitor is 3.5, then the acid metering pump is started and operates in accordance with the hertz that ensures the reduction acceleration becomes zero.

[0117] B. If the feedback signal value increases, the acid metering pump Hz continues to increase by 5 until the feedback signal value decreases, and then proceed according to step A.

[0118] When the feedback signal value of the pH online monitor is less than 3.5, the acid metering pump stops and the wastewater metering pump starts to take in water until the feedback signal value of the pH online monitor is greater than 3.5 and the above steps are followed.

[0119] As the instruction manual Figure 2 As 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, the acidic organic wastewater flows into the electrolytic cell, and the hydroxyl radicals generated in the electrolytic cell degrade the organic matter therein, and each electrode group is arranged in sequence in the electrolytic cell 21, and the electrode group includes a first anode 25, a first cathode 26, a second anode 27 and a second cathode 28 arranged in sequence, the first cathode 26 and the second cathode 28 are both carbon-based cathodes, the first anode 25 is a carbon-based anode, and the second anode 27 is an induction iron-based anode. The plates used for each cathode and anode are all arranged vertically, and the preparation method of each electrode and the arrangement of the electrodes in 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 provide hydrogen peroxide to the electrolytic cell 21. The organic wastewater is adjusted to acidity in the acid adjustment unit 1 and sent to the electrolytic cell 21. The hydroxyl radicals generated in the electrolytic cell 21 can degrade organic matter in the organic wastewater, thereby purifying the organic wastewater. A circulation pipeline is provided on the electrolytic cell 21 to circulate the solution in the electrolytic cell 21. The circulation pump 24 is provided on the circulation pipeline, and the ultraviolet lamp 22 is provided on the circulation pipeline.

[0120] 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 and the amount of hydrogen peroxide added.

[0121] Preferably, the electrolytic cell is connected to two circulation pipelines, which are controlled separately, one for use and one for standby. The circulation pump is mainly used to enhance the mass transfer effect of the photoelectric oxidation unit and reduce the concentration range in the electrolytic cell. The flow rate of the circulation pump is shown in Formula 5). The ultraviolet lamp is arranged at the outlet of the circulation pump, and the wavelength of the ultraviolet lamp is 200-300nm, preferably in the form of one for use and one for standby. A valve is provided on the circulation pipeline, and the ultraviolet lamp is provided with an inspection port. By switching the valve, the sludge attached to the ultraviolet lamp can be cleaned in time. The ultraviolet lamp acts on the mixed solution in the circulation pipeline, which can effectively promote Fe 2+ and the regeneration of hydroxyl radicals.

[0122] The photoelectric oxidation unit 2 also includes a DC power supply 29 connected to the electrode plates in the electrode group. The electrolytic cell is also connected to a liquid level meter for monitoring the liquid level of the solution in the electrolytic cell. Each pipeline of the photoelectric oxidation unit is provided with a flow meter and a valve for adjusting the flow on the pipeline.

[0123] The alkali adjustment unit 3 includes a neutralization tank 31. The organic wastewater degraded by the photoelectric oxidation unit enters the neutralization tank 31. The neutralization tank 31 is provided with a stirrer. The neutralization tank 31 is connected to an alkali liquid tank 32. An alkali adding pipeline is connected between the neutralization tank 31 and the alkali liquid tank 32. The neutralization tank 31 is also connected to a pH online monitor for monitoring the pH of the solution in the neutralization tank. The pH online monitor is interlocked with the alkali adding metering pump on the alkali adding pipeline. The organic wastewater adjusts the pH to 7.5-8.5 in the neutralization tank. The specific adjustment process is as follows:

[0124] (1) When the feedback signal value of the pH online monitor is less than 8.5, the alkali metering pump hertz is increased by 5. After the reaction time is 10 seconds, the feedback signal value of the pH online monitor before and after 10 seconds is compared.

[0125] A. If the feedback signal value increases, the Hz of the alkali metering pump decreases by 1. After the reaction time continues for 10s, compare the feedback signal value of the pH online monitor and the increase acceleration before and after 10s. If the increase acceleration becomes smaller (the formula for the decrease acceleration is a = (lg10s before feedback signal value - lg10s after feedback signal value) / 10), the Hz of the alkali metering pump continues to decrease by 1 until the decrease acceleration becomes zero. When the decrease acceleration becomes zero, if the feedback signal value of the pH online monitor is less than 8.5, the neutralization tank stops the entry of organic wastewater, and the alkali metering pump operates at a Hz that ensures the increase acceleration becomes zero. When the feedback signal value of the pH online monitor is 8.5, start the water inlet pump at the feed end of the neutralization tank. When the decrease acceleration becomes zero, if the feedback signal value of the pH online monitor is less than 8.5, the alkali metering pump stops, and the water inlet pump continues to take in water until the feedback signal value of the pH online monitor is 8.5, then start the alkali metering pump and operate at a Hz that ensures the increase acceleration becomes zero.

[0126] B. If the feedback signal value remains unchanged, continue to increase the Hz of the alkali metering pump by 5 until the feedback signal value decreases, and then follow step A.

[0127] (2) When the feedback signal value of the pH online monitor is greater than 8.5, the alkali metering pump stops and the water inlet pump continues to inlet water until the feedback signal value of the pH online monitor is less than 8.5 and then the steps in (1) are executed.

[0128] Preferably, the alkali adjustment unit 3 further comprises a buffer tank 33, which is connected to the neutralization tank 31 to facilitate the full mixing of the alkali solution and the organic wastewater. In order to facilitate the precipitation of alum flowers in the organic wastewater, part of the sludge precipitation is returned to the buffer tank 33, and the crystal seed value-added effect in the precipitate is utilized to facilitate precipitation and sedimentation, thereby reducing the cost of the reagent.

[0129] The flocculation and sedimentation unit 4 includes an integrated flocculation and sedimentation tank, as shown in the attached manual. Figure 3As shown, it includes a flocculation tank and a sedimentation tank 43. The flocculation tank includes a first flocculation tank 41 and a second flocculation tank 42. The first flocculation tank 41 is connected to the buffer tank 33. The feed port of the second flocculation tank 42 is connected to the discharge port of the first flocculation tank 41. The first flocculation tank 41 is connected to a PAC tank 44 (PAC: polyaluminium chloride) for preliminary precipitation of pollutants in organic wastewater. The second flocculation tank is connected to a PAM tank 45 (PAM: polyacrylamide) for further precipitation of organic matter in organic wastewater. The sedimentation tank 43 is connected to the second flocculation tank 42. Pollutants in organic wastewater are mixed with flocculants in the flocculation tank to form alum flowers, which are sent to the sedimentation tank 43. The sedimentation tank 43 is precipitated to obtain sludge sediment and supernatant. The sludge sediment can be collected in the sludge concentration tank for further treatment. Part of the sludge sediment can be returned to the buffer tank, and the supernatant overflows to the next process. The precipitates in the buffer tank, the first flocculation tank, and the second flocculation tank can also be collected in the sludge concentration tank for further treatment. The sludge precipitates are returned to the buffer tank 33 through the sludge return pipe, which can effectively utilize the unreacted flocculants therein and greatly reduce the cost of the reagents. The sludge return pipe is provided with a sludge return pump, and the sludge return pump flow Q2 can be calculated according to the following formula:

[0130] Q2=η×Q 8)

[0131] In formula 8), Q is the water volume treated by the system, in m 3 / h; η is the reflux coefficient, which ranges from 3% to 5%.

[0132] The organic wastewater is flocculated and precipitated in the flocculation sedimentation tank using alum flower mirror technology, an image recognition alum flower particle size and density model is established, the dosage is intelligently adjusted, and the cost of chemicals and labor is greatly reduced.

[0133] The specific method is as follows:

[0134] 1. Establish the particle size and density per unit volume of alum flowers under different PAC and PAM conditions, and establish a generalized model;

[0135] 2. Continuously optimize model parameters through machine learning based on actual water quality operation conditions;

[0136] 3. Utilize the characteristics of alum flowers captured by underwater high-definition cameras, automatically feedback the operating status through digital models, adjust the frequency of PAC and PAM dosing pumps, greatly improve the water quality of the effluent, and save more than 30% of the dosing amount.

[0137] Preferably, the sedimentation tank 43 is preferably an inclined tube sedimentation tank, and a backwashing device is provided in the sedimentation tank 43, and the backwashing device includes a high-pressure pulse fan 46 and a backwashing air duct 47, and the flushing method adopts an intermittent cross-cleaning mode. The air volume Q3 of the high-pressure pulse fan can be calculated according to the following formula:

[0138] Q3=q×L×b 9)

[0139] In formula 9), q is the backwash intensity, ranging from 20 to 801 m 3 / (m 2 *h); L is the length of the inclined tube sedimentation tank; b is the distance between the backwash air ducts, which is 1 to 2m.

[0140] Those skilled in the art will appreciate that the present invention can be implemented in many other specific forms without departing from the spirit and scope of the present invention. Although embodiments of the present invention have been described, it should be understood that the present invention should not be limited to this embodiment, and those skilled in the art can make changes and modifications within the spirit and scope of the present invention as defined by the appended claims.

Claims

1. A method for degradation of organic wastewater, characterized in that: The following steps are involved: Adjust the pH of organic wastewater to acidic; Acidic organic wastewater and hydrogen peroxide are added to the photoelectric oxidation unit. The hydrogen peroxide reacts with the electrode group in the photoelectric oxidation unit to generate hydroxyl radicals for degrading acidic organic wastewater. The Fe 2+ and hydroxyl radical regeneration; The pH of the wastewater after the photoelectric oxidation treatment is adjusted to alkaline, and a flocculant is added to the alkaline wastewater to obtain sludge precipitation and supernatant, and the supernatant is subsequently treated.

2. The method for degradation of organic wastewater according to claim 1, characterized in that: There are multiple electrode groups, each of which includes a first anode, a second anode and a carbon-based cathode. The first anode and the second anode are arranged at intervals. The first anode is a carbon-based anode, and the second anode is an induction iron-based anode. The spacing between each adjacent electrode piece is 1 to 2 mm.

3. The method for degradation of organic wastewater according to claim 2, characterized in that: The preparation method of the carbon-based anode is: 1) Adding additives to the carbon-based raw material powder, stirring and mixing, and extruding the mixture to obtain a carbon-based product; 2) calcining the carbon-based article to carbonize the additive; 3) impregnating the calcined carbon-based product with a liquid impregnant, wherein the impregnant penetrates into the electrode pores of the carbon-based product; 4) performing secondary calcination on the impregnated carbon-based product to carbonize the impregnant; 5) The carbon-based product after the secondary calcination is subjected to high-temperature calcination at a temperature not lower than 2300° C. to obtain a carbon-based anode.

4. The method for degradation of organic wastewater according to claim 3, characterized in that: In step 1, extruding the mixture specifically comprises the following steps: Cooling: discharge the volatile components in the mixture, then reduce the temperature of the mixture to 90-120℃ and keep it warm for 20-30min; Loading: Compact the cooled mixture at 4-10 MPa for 2-3 min; Pre-pressing: compact the mixture at 20-25 MPa for 3-5 minutes, and evacuate the mixture during compaction; Extrusion: The pre-pressed mixture is extruded at 5-15 MPa, and then sheared and cooled to obtain a carbon-based product.

5. The method for degradation of organic wastewater according to claim 3, characterized in that: In step 3, the impregnation of the carbon-based product specifically includes the following steps: Clean the surface of the calcined carbon-based product and preheat it to 260-380°C for 6-10 hours; The preheated carbon-based product is placed in an impregnation tank, the tank is evacuated, and then an impregnating agent is injected into the impregnation tank; The tank is pressurized to 1.2-1.5 MPa, immersed for 3-4 hours, and cooled to complete the impregnation of the carbon-based product.

6. The method for degradation of organic wastewater according to claim 2, characterized in that: The preparation method of the carbon-based cathode is as follows: placing the carbon-based raw material in a high-temperature furnace, evacuating the high-temperature furnace or introducing an inert gas, heating to 2200-2500° C. at a heating rate of 100-300° C. / h, keeping the temperature for a period of time, and then cooling to obtain the carbon-based cathode.

7. The method for treating degraded organic wastewater according to claim 1, characterized in that: Monitor the ORP measured value in the photoelectric oxidation unit. If the ORP measured value is less than the ORP set value, increase the amount of hydrogen peroxide added until the ORP measured value is equal to the ORP set value; if the ORP measured value is greater than the ORP set value, reduce the amount of hydrogen peroxide added until the ORP measured value is equal to the ORP set value.

8. The method for treating organic wastewater according to claim 1, characterized in that: The ion concentration of iron ions in the photoelectric oxidation unit is 20 mg / L to 40 mg / L. If the ion concentration of iron ions is detected to be less than 20 mg / L, the anode voltage is increased. If the ion concentration of iron ions is detected to be greater than 40 mg / L, the anode voltage is reduced.

9. The method for treating degraded organic wastewater according to claim 1, characterized in that: The alkaline organic wastewater is added with a flocculant to precipitate, and a backwashing device is used to backwash the precipitate. The backwashing intensity is 20 to 80 m 3 / (m 2 *h); returning part of the sludge sediment to the alkaline wastewater.

10. A degradation treatment system for organic wastewater, characterized in that: include: Acid adjustment unit, used to adjust the pH of organic wastewater to acidic; The photoelectric oxidation unit comprises an electrolytic cell and an ultraviolet lamp arranged on the electrolytic cell, wherein the feed port of the electrolytic cell is connected to the discharge port of the acid conditioning unit, and a plurality of electrode groups are arranged in the electrolytic cell; An alkali adjustment unit, used for adjusting the pH of the organic wastewater to alkaline, the alkali adjustment unit being connected to the electrolytic cell; The flocculation and sedimentation unit comprises 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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