A pretreatment device and method for full-process control of pesticide wastewater

Abstract

The present invention discloses a pretreatment device and method for the full-process control of pesticide wastewater, including a pH adjustment tank, a micro-electrolysis tank, a Fenton tank, a neutralization tank, and a secondary sedimentation tank; the pH adjustment tank adopts multi-point water distribution as the water inlet method, and the acid-base adjustment adopts DCS fully automated control. A three-phase separator and an inclined tube sedimentation device are provided on the top of the micro-electrolysis tank; the Fenton tank adopts internal circulation and external circulation, and a central tube and a sludge hopper are provided inside the secondary sedimentation tank. The present invention realizes the separation of gas, liquid, and solid phases through three-phase separation and inclined tube sedimentation, effectively making iron filings present a fully mixed state, improving the reaction efficiency and rate, the internal circulation of the Fenton tank reduces the generation of waste gas, and the external circulation further removes COD and chroma in the wastewater. On the one hand, it avoids the compaction and channeling of micro-electrolysis fillers, improves the treatment efficiency of micro-electrolysis, and on the other hand, through the control of the whole process, greatly reduces manpower, improves the accuracy of work, and reduces the difficulty of management.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and more specifically, to a pretreatment device and method for full-process control of pesticide wastewater. Background Art

[0002] Pesticide wastewater is one of the most challenging issues in modern industrial wastewater treatment and has become a focus of public attention. During the pesticide production process, there are many varieties of pesticides, with significant differences in their chemical structures, different raw materials and synthesis processes, multiple reaction steps, and a long production process. Therefore, pesticide wastewater generally has the following characteristics:

[0003] (1) High concentration of organic matter: The COD concentration of wastewater generated during pesticide production is generally 10,000 mg / L, and sometimes even as high as 10 5 mg / L.

[0004] (2) Complex organic components: Pesticide production involves many organic chemical reactions, and many wastewaters contain not only raw materials but also many by-products and intermediates.

[0005] (3) High toxicity and difficult to biodegrade: Pesticide wastewater contains a considerable amount of organic matter and some inorganic matter that have a stable chemical structure, are difficult to be degraded by microorganisms, and are highly toxic to microorganisms.

[0006] (4) Foul or irritating odor: Pesticide wastewater often has a foul or irritating odor, which is irritating to the human respiratory tract and mucous membranes. In severe cases, it can cause poisoning symptoms and endanger health.

[0007] (5) Unstable water quality and quantity: Due to unstable production processes, operational management and other issues, a large amount of wastewater is discharged per ton of product, which brings certain difficulties to wastewater treatment.

[0008] At present, the treatment methods for pesticide wastewater basically include three treatment technologies: physical-chemical method, chemical method and biochemical method. Most of them adopt the combination of physical-chemical method and biochemical method. Physical-chemical method is generally used as a pretreatment method to treat difficult biodegradable substances, so as to remove some pollutants, improve the biodegradability of wastewater and improve treatment efficiency. Physical-chemical method generally includes:

[0009] (1) Zero-valent iron (ZVI) reduction

[0010] Zero-valent iron (ZVI) reduction technology is widely used in the treatment of pollutants such as nitroaromatic compounds, chlorinated organics, azo dyes, and organochlorine pesticides. This method effectively reduces the toxicity of nitroanthraquinone to microorganisms by converting the nitro group in nitroanthraquinone into amino groups, creating conditions for further biochemical treatment and enhancing the chemical oxidation degradation of pollutants.

[0011] (2) Fenton oxidation

[0012] Add appropriate amount of H2O2 solution to the wastewater to react with Fe 2+ The Fenton reagent has a strong oxidizing ability, which is particularly suitable for the treatment of difficult-to-degrade organic wastewater. The reason why Fenton reagent has a strong oxidizing ability is that H2O2 is 2+ Catalytic decomposition produces OH (hydroxyl radical).

[0013] (3) Flocculation and precipitation

[0014] After zero-valent iron (ZVI) reduction and Fenton oxidation degradation, the COD of the wastewater was greatly reduced, and the BOD5 / COD was also greatly improved. However, a large amount of Fe 2+ and Fe 3+ , which is very detrimental to the subsequent biochemical treatment. Therefore, the final effluent of the Fenton oxidation reaction unit must first be adjusted with Ca(OH)2 emulsion or NaOH solution. Coagulation precipitation can make the Fe 2+ and Fe 3+ They exist in the form of Fe(OH)2 and Fe(OH)3 respectively. Since the new ecological Fe(OH)2 and Fe(OH)3 colloids have a large specific surface area and strong adsorption capacity, the colloidal COD and color in the wastewater can be removed by adsorption precipitation. In order to improve the sedimentation effect of flocs, PAC and PAM can be added to the wastewater after alkali addition, so that the generated fine colloids are precipitated to form larger flocs, which will settle at a faster rate.

[0015] Patent document CN217025666U discloses a wastewater treatment device that combines micro-electrolysis and biological contact oxidation. The device comprises a micro-electrolysis tank, an intermediate tank, and a biological contact oxidation tank. The micro-electrolysis tank is filled with sintered iron-carbon filler, which has a good treatment effect on wastewater. However, after a period of operation in the fixed-bed micro-electrolysis device, the iron-carbon filler is prone to passivation and compaction, resulting in blockage and channeling. Patent document CN107935308A discloses a method for treating pesticide wastewater. The method uses a "micro-electrolysis-Fenton oxidation-neutralization and precipitation treatment combined with UASB and aerobic activated sludge treatment" process, which can achieve a COD removal rate of 98% in pesticide wastewater. However, the Fenton oxidation process uses aeration and stirring, which produces a large amount of waste gas during the reaction.

[0016] Therefore, the following problems exist in the pretreatment of pesticide wastewater: (1) After a period of operation, the iron-carbon filler in the fixed-bed micro-electrolysis device is prone to passivation and hardening, resulting in blockage and channeling, which greatly reduces the treatment efficiency; (2) A large amount of waste gas is generated during the stirring process of the wastewater, and the stirring of the reagent is uneven, resulting in poor treatment effect and low efficiency; (3) The wastewater treatment process is complex and requires manual operation, resulting in large errors and uncontrollable. Therefore, it is necessary to propose a pretreatment device and method for pesticide wastewater with full process control to at least partially solve the problems existing in the existing technology. Summary of the Invention

[0017] The Summary of the Invention introduces a series of simplified concepts that will be further described in the Detailed Description of the Invention. The Summary of the Invention is not intended to limit the key features and essential features of the claimed technical solution, nor is it intended to determine the scope of protection of the claimed technical solution.

[0018] To at least partially solve the above problems, the present invention provides a pretreatment device for pesticide wastewater full-process control, comprising:

[0019] The pH adjustment tank, micro-electrolysis tank, Fenton tank, neutralization tank and secondary sedimentation tank are connected in sequence by several pipes.

[0020] Preferably, a raw water inlet pipe for chemical wastewater is provided on the upper part of the pH adjusting tank, a pH adjusting tank stirring device is fixedly installed on the top of the pH adjusting tank, a pH adjusting tank sewage lifting pump is provided on the outside of the pH adjusting tank, and a pH adjusting tank outlet pipe is provided at the bottom of the pH adjusting tank. The pH adjusting tank outlet pipe is connected to the input end of the pH adjusting tank sewage lifting pump, and the output end of the pH adjusting tank sewage lifting pump is connected to the micro-electrolysis tank through the micro-electrolysis inlet pipe.

[0021] Preferably, a channel steel is installed in the middle and upper part of the micro-electrolysis tank, and a guide baffle is vertically connected to the middle of the channel steel. The guide baffle divides the interior of the micro-electrolysis tank into two chambers. Ultrasonic oscillation plates are provided on both sides of the inner wall of the micro-electrolysis tank. A three-phase separator is installed on the upper part of the channel steel, and an inclined tube sedimentation is provided on the upper part of the three-phase separator, and a micro-electrolysis water outlet tank is provided on the upper part of the inclined tube sedimentation.

[0022] Preferably, the water inlet pipe at the bottom of the Fenton tank is connected to the micro-electrolysis water outlet tank through the micro-electrolysis water outlet pipe, a lower circulation pipe is provided at the bottom of the Fenton tank, a circulation pump is provided outside the Fenton tank, the lower circulation pipe is connected to the input end of the circulation pump, the output end of the circulation pump is connected to the upper circulation pipe provided on the upper part of the Fenton tank through a provided pipeline, the upper circulation pipe is provided with an upper circulation pipe electric ball valve, the output end of the circulation pump is connected to the micro-electrolysis water inlet pipe on the micro-electrolysis tank through a provided return pipe, the return pipe is provided with a return pipe electric ball valve, a Fenton tank outlet pipe is provided on the upper part of the Fenton tank, and the Fenton tank outlet pipe is connected to the neutralization tank.

[0023] Preferably, a paddle stirring device is installed in the neutralization tank. The effluent of the neutralization tank is connected to the secondary sedimentation tank through a water passing hole. A central cylinder and a sludge hopper are arranged inside the secondary sedimentation tank. A secondary sedimentation tank effluent trough is arranged at the top of the secondary sedimentation tank. A secondary sedimentation tank effluent pipe is arranged at the secondary sedimentation tank effluent trough. A sludge discharge pipe is arranged at the bottom of the secondary sedimentation tank. A secondary sedimentation tank sludge discharge pump is arranged outside the secondary sedimentation tank. The sludge inlet end of the secondary sedimentation tank sludge discharge pump is connected to the sludge discharge pipe.

[0024] Preferably, the pH adjustment tank stirring device includes a stirring motor and a shaft rod. The stirring motor is vertically arranged. The lower end of the stirring motor is fixedly connected to the upper end of the shaft rod. A spiral ribbon mixer is fixedly connected to the outer wall of the shaft rod. A hinge-opening turbine is fixedly connected to the outer wall at the bottom of the shaft rod. The blades of the hinge-opening turbine are arranged at an inclination of 45°. The spiral ribbon mixer includes an outer spiral ribbon and an inner spiral ribbon. The outer spiral ribbon rotates to push the wastewater from the upper and lower ends of the pH adjustment tank to the middle section, and the inner spiral ribbon rotates to push the wastewater from the middle section of the pH adjustment tank to the upper and lower ends.

[0025] Preferably, the micro-electrolysis inlet pipe adopts an "E"-shaped water inlet, and the upper, middle, and lower parts of the micro-electrolysis tank are simultaneously filled with water. The micro-electrolysis inlet pipe is connected to the iron powder automatic dosing device, and a check valve is installed at the micro-electrolysis inlet pipe.

[0026] Preferably, a water distribution pipe connected to the upper circulation pipe is arranged inside the Fenton tank. The water distribution pipe adopts a form of two groups of "abundant"-shaped water distribution. A hydrogen peroxide dosing tank is connected to the top of the Fenton tank.

[0027] Preferably, an ultraviolet photocatalyst is arranged on the reflux pipe.

[0028] Preferably, a pH meter and a liquid level meter for the pH adjustment tank are installed on the upper part of the pH adjustment tank. There is a 10% sulfuric acid solution in the sulfuric acid dosing tank, which is added to the pH adjustment tank through a sulfuric acid metering pump. A sulfuric acid pneumatic regulating valve is arranged on the sulfuric acid dosing pipeline. There is a 28% liquid alkali solution in the liquid alkali dosing tank, which is added to the pH adjustment tank through a liquid alkali metering pump. A liquid alkali pneumatic regulating valve I is arranged on the liquid alkali dosing pipeline. The pH meter for the pH adjustment tank, the liquid level meter for the pH adjustment tank, the sulfuric acid pneumatic regulating valve, the liquid alkali pneumatic regulating valve I, the sulfuric acid metering pump, and the liquid alkali metering pump are all electrically connected to the DCS controller.

[0029] Preferably, a pretreatment method for the whole-process control of pesticide wastewater adopts the pretreatment device for the whole-process control of pesticide wastewater as described above. The steps are as follows:

[0030] S1: The pesticide wastewater to be treated enters the pH adjustment tank, and sulfuric acid and liquid alkali are added through DCS control to adjust the pH value of the wastewater between 3 and 4;

[0031] S2: The pH-adjusted wastewater and catalyst in the pH adjustment tank enter the micro-electrolysis tank, and the iron-carbon filler and sewage react in the micro-electrolysis tank. The mixed liquid after the reaction in the micro-electrolysis tank passes through a three-phase separator to separate the wastewater, iron-carbon filler, and exhaust gas into three phases. The wastewater is precipitated through an inclined tube to remove the iron-carbon filler and then discharged from the micro-electrolysis outlet pipe by gravity into the Fenton tank. The iron-carbon filler returns to the reaction area of ​​the micro-electrolysis tank through gravity sedimentation, and the exhaust gas is connected to the exhaust pipe network through the exhaust pipe;

[0032] S3: Hydrogen peroxide is added to the Fenton tank to fully react with the wastewater. When the COD value is higher than the set value, the wastewater in the Fenton tank is returned to the micro-electrolysis tank. When the COD value is lower than the set value, the wastewater in the Fenton tank is transported to the neutralization tank.

[0033] S4: Liquid alkali is added to the neutralization tank to adjust the pH value. PAC solution and PAM solution are added to the wastewater with liquid alkali added, so that the generated fine colloids are precipitated to form larger flocs. The wastewater in the neutralization tank is transported to the secondary sedimentation tank, and the suspended matter in the water is removed by coagulation and sedimentation. The sludge is then transported to the subsequent physicochemical sludge tank.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] The present invention provides a pretreatment device and method for full-process control of pesticide wastewater. The device achieves gas-liquid-solid three-phase separation through three-phase separation and inclined tube sedimentation, effectively making iron filings fully mixed, thereby improving reaction efficiency and rate. The internal circulation of the Fenton tank reduces the generation of waste gas, and the external circulation further removes COD and chroma in the wastewater. On the one hand, it avoids the compaction and channeling of micro-electrolysis fillers and improves the treatment efficiency of micro-electrolysis. On the other hand, through full-process control, it greatly reduces manpower, improves work accuracy, and alleviates management difficulty. The device is suitable for the pretreatment of pesticide wastewater with high organic matter concentration and high toxicity, can effectively remove organic matter in pesticide wastewater, reduce the toxicity of wastewater, and improve the biodegradability of wastewater, thereby realizing full-process control of the pretreatment device.

[0036] (1) A channel steel is installed in the middle and upper part of the micro-electrolysis tank, and a guide baffle is vertically welded in the middle of the channel steel. The guide baffle divides the interior of the micro-electrolysis tank into two chambers, effectively avoiding the loss of iron-carbon filler; ultrasonic oscillation plates are installed on both sides of the micro-electrolysis tank, and ultrasonic oscillation is performed on the iron-carbon filler and sewage through the ultrasonic oscillation plates to improve the fluidity and contact exchange efficiency between sewage and filler; a three-phase separator is installed on the upper part of the channel steel, and wastewater, iron-carbon filler and air are fully contacted in three-dimensional directions from bottom to top, in a turbulent state, and momentum is transferred. After passing through the three-phase separator, the air and the waste gas generated by the reaction enter the subsequent gas treatment process through the exhaust pipe; an inclined tube sedimentation is installed on the upper part of the three-phase separator to further remove the iron-carbon filler. A micro-electrolysis outlet trough is installed on the upper part of the inclined tube sedimentation. The micro-electrolysis outlet trough is connected to the micro-electrolysis outlet pipe, and the outlet water flows to the Fenton tank.

[0037] (2) The water inlet of the Fenton tank adopts multi-point layered water distribution. The top of the Fenton tank is connected to a hydrogen peroxide dosing tank. The Fenton tank is equipped with an external circulation device. The inlet of the external circulation device is tangential to the Fenton tank and the water inlet direction is clockwise. There is a reflux device in the upper part of the Fenton tank. The water outlet of the reflux device is connected to the micro-electrolysis tank. An ultraviolet photocatalyst is installed on the reflux device pipe section. The ultraviolet catalysis is combined to promote the decomposition of small molecular organic matter, thereby improving the COD degradation efficiency. The ultraviolet photocatalyst promotes the conversion of metal elements in the wastewater. The Fenton tank 24 uses ultraviolet radiation to promote Fe 3+ / Fe 2+ Conversion, reduction of Fe 2+ The amount of addition and the amount of iron sludge produced.

[0038] (3) A pH meter and a pH level gauge are installed on the upper part of the pH regulating tank. There is a 10% sulfuric acid solution in the sulfuric acid dosing tank, which is added to the pH regulating tank through a sulfuric acid metering pump. A sulfuric acid pneumatic regulating valve is provided on the sulfuric acid dosing pipeline. There is a 28% liquid alkali solution in the liquid alkali dosing tank, which is added to the pH regulating tank through a liquid alkali metering pump. A liquid alkali pneumatic regulating valve 1 is provided on the liquid alkali dosing pipeline. The pH meter, the pH level gauge, the sulfuric acid pneumatic regulating valve, the liquid alkali pneumatic regulating valve 1, the sulfuric acid metering pump and the liquid alkali metering pump are all electrically connected to the DCS controller. When the pH value in the pH regulating tank is higher than 4, the DCS controls the increase of the sulfuric acid pneumatic regulating valve. When the pH value in the pH regulating tank is lower than 3, the DCS controls the increase of the liquid alkali pneumatic regulating valve 1, so that the pH value in the pH regulating tank is stabilized at around 3.

[0039] The present invention relates to a pretreatment device and method for full-process control of pesticide wastewater. Other advantages, objectives and features of the present invention will be partially reflected in the following description, and will also be understood by technicians in this field through research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0041] Figure 1 This is a structural schematic diagram of a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0042] Figure 2 This is a schematic diagram of the first partial structure of a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0043] Figure 3 This is a schematic diagram of a second partial structure of a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0044] Figure 4 This is a structural schematic diagram of a stirring device for a pH adjustment tank in a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0045] Figure 5 This is a schematic diagram of water inlet and water distribution in a pH adjustment tank in a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0046] Figure 6 This is a top view of the raw water inlet pipe structure in a pretreatment device for full-process control of pesticide wastewater according to the present invention;

[0047] Figure 7 This is a schematic diagram of the cross-sectional structure of the raw water inlet pipe at point a in a pretreatment device for full-process control of pesticide wastewater according to the present invention.

[0048] Figure 1: pH adjustment tank; 2: Raw water inlet pipe; 3: pH meter for pH adjustment tank; 4: Liquid level gauge for pH adjustment tank; 5: Pneumatic regulating valve for sulfuric acid; 6: Pneumatic regulating valve for liquid alkali; 7: Sulfuric acid dosing tank; 8: Sulfuric acid metering pump; 9: Liquid alkali dosing tank; 10: Liquid alkali metering pump; 11: pH adjustment tank outlet pipe; 12: Sewage lifting pump for pH adjustment tank; 13: Micro-electrolysis inlet pipe; 14: Automatic iron powder dosing device; 15: Micro-electrolysis tank; 16: Diversion baffle; 17: Ultrasonic vibration Swing plate; 18. Channel steel; 19. Three-phase separator; 20. Inclined tube sedimentation; 21. Exhaust pipe; 22. Micro-electrolysis outlet tank; 23. Micro-electrolysis outlet pipe; 24. Fenton tank; 25. COD meter; 26. Fenton tank level gauge; 27. Hydrogen peroxide dosing tank; 28. Hydrogen peroxide metering pump; 29. ​​Hydrogen peroxide flow meter; 30. Hydrogen peroxide electric ball valve; 31. Lower circulation pipe; 32. Circulation pump; 33. Upper circulation pipe; 34. Water distribution pipe; 35. Return pipe electric ball valve; 36. Upper circulation pipe 37. Electric ball valve for pipe; 38. Fenton tank outlet pipe; 39. Neutralization tank; 40. pH meter for neutralization tank; 41. Paddle stirring device; 42. Frame mixer; 43. UV catalyst; 44. Second pneumatic regulating valve for liquid alkali; 45. PAC dosing tank; 46. PAC metering pump; 47. PAC dosing flow meter; 48. PAC electric ball valve; 49. PAM (female) dosing tank; 50. PAM (female) metering pump; 51. PAM (female) dosing flow meter; 5 2. PAM (female) electric ball valve; 53. Secondary sedimentation tank inlet pipe; 54. Secondary sedimentation tank; 55. Center tube; 56. Sludge hopper; 57. Secondary sedimentation tank outlet trough; 58. Secondary sedimentation tank outlet pipe; 59. Sludge outlet pipe; 60. Secondary sedimentation tank sludge pump; 61. pH adjustment tank stirring device; 61-1. Stirring motor; 61-2. Shaft; 61-3. Outer spiral band; 61-4. Inner spiral band; 61-5. Folding to open turbine; 62. Electric ball valve for Fenton tank outlet pipe; 63. Check valve. DETAILED DESCRIPTION

[0049] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments so that those skilled in the art can implement the invention with reference to the description.

[0050] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0051] like Figure 1-7 As shown, the present invention provides a pretreatment device for full-process control of pesticide wastewater, including: a pH adjustment tank 1, a micro-electrolysis tank 15, a Fenton tank 24, a neutralization tank 39 and a secondary sedimentation tank 54 connected in sequence by several pipes.

[0052] The upper part of the pH adjustment tank 1 is provided with a raw water inlet pipe 2 for chemical wastewater. The raw water inlet pipe 2 adopts an "I"-shaped water distribution form, with multiple holes with a diameter of 25 mm opened obliquely upward, a hole spacing of 200 mm, and a number of 60 holes. The upper part of the pH adjustment tank 1 is provided with a pH adjustment tank pH meter 3 and a pH adjustment tank liquid level gauge 4. There is a 10% sulfuric acid solution in the sulfuric acid dosing tank 7, which is added to the pH adjustment tank 1 through a sulfuric acid metering pump 8. A sulfuric acid pneumatic regulating valve 5 is provided on the sulfuric acid dosing pipeline. There is a 28% liquid alkali solution in the liquid alkali dosing tank 9, which is metered through the liquid alkali. The pump 10 adds liquid to the pH regulating tank 1. A liquid alkali pneumatic regulating valve 6 is provided on the liquid alkali dosing pipeline. The pH meter 3 of the pH regulating tank, the liquid level gauge 4 of the pH regulating tank, the sulfuric acid pneumatic regulating valve 5, the liquid alkali pneumatic regulating valve 6, the sulfuric acid metering pump 8 and the liquid alkali metering pump 10 are all electrically connected to the DCS controller. When the pH value in the pH regulating tank 1 is higher than 4, the DCS controls the sulfuric acid pneumatic regulating valve 5 to increase. When the pH value in the pH regulating tank 1 is lower than 3, the DCS controls the liquid alkali pneumatic regulating valve 6 to increase, so that the pH value in the pH regulating tank 1 is stabilized at around 3.

[0053] A pH regulating tank sewage lift pump 12 is provided on the outside of the pH regulating tank 1. A pH regulating tank outlet pipe 11 is provided at the bottom of the pH regulating tank 1. The pH regulating tank outlet pipe 11 is connected to the input end of the pH regulating tank sewage lift pump 12. The output end of the pH regulating tank sewage lift pump 12 is connected to the micro-electrolysis tank 15 via a micro-electrolysis inlet pipe 13. The pH regulating tank outlet pipe 11 transports wastewater to the micro-electrolysis tank 15 via the pH regulating tank sewage lift pump 12. The pH regulating tank liquid level meter 4 is linked to the pH regulating tank sewage lift pump 12 to control the start and stop of the pump according to the liquid level of the pH regulating tank 1. When the liquid level is lower than the designed low water level, the pH regulating tank sewage lift pump 12 is automatically shut down by the DCS control. When the liquid level is higher than the designed high water level, the pH regulating tank sewage lift pump 12 is automatically started by the DCS control.

[0054] A pH adjusting tank stirring device 61 is fixedly installed on the top of the pH adjusting tank 1. The pH adjusting tank stirring device 61 includes a stirring motor 61-1 and a shaft 61-2. The stirring motor 61-1 is vertically arranged, and the lower end of the stirring motor 61-1 is fixedly connected to the upper end of the shaft 61-2. The outer wall of the shaft 61-2 is fixedly connected to a spiral ribbon mixer, and the outer wall of the bottom of the shaft 61-2 is fixedly connected to a hinged open turbine 61-5. The blades of the hinged open turbine 61-5 are inclined at 45 degrees. The spiral ribbon mixer includes an outer spiral ribbon 61-3 and an inner spiral ribbon 61-4. The outer spiral ribbon 61-3 rotates to push the wastewater from the upper and lower ends of the pH adjusting tank 1 to the middle section, and the inner spiral ribbon 61-4 rotates to push the wastewater from the middle section of the pH adjusting tank 1 to the upper and lower ends, thereby forming convection mixing. The spiral structures of the outer spiral ribbon 61-3 and the inner spiral ribbon 61-4 cooperate with the rotation direction of the shaft 61-2 to push the wastewater inside the pH adjusting tank 1 to the pH adjusting tank outlet pipe 11.

[0055] The micro-electrolysis water inlet pipe 13 adopts an "E"-shaped water inlet, and water enters the upper, middle and lower parts of the micro-electrolysis tank 15 simultaneously, dividing the water flow into multiple parallel streams. On the one hand, it increases the probability of collision with the iron-carbon filler, and on the other hand, it plays an excellent hydraulic stirring role. The iron-carbon filler of the micro-electrolysis tank 15 uses "zero-valent iron + activated carbon filler + auxiliary metal catalyst" as the reaction carrier. When the wastewater passes through the iron-carbon filler under acidic conditions, the pollutants in the wastewater undergo redox reactions on the surface of the filler. The zero-valent iron acts as an anode to oxidize the pollutants and lose electrons to become Fe 2+ , activated carbon acts as a cathode to react with pollutants in a reduction reaction. The iron-carbon powder-composite catalyst is connected to the micro-electrolysis water inlet pipe 13 using an automatic iron powder dosing device 14. A check valve 63 is installed at the micro-electrolysis water inlet pipe 13 to prevent water backflow. A channel steel 18 is installed in the upper middle part of the micro-electrolysis tank 15. A guide baffle 16 is vertically welded to the middle of the channel steel 18. The guide baffle 16 divides the interior of the micro-electrolysis tank 15 into two chambers, effectively preventing the loss of iron-carbon filler. Ultrasonic oscillation plates 17 are installed on both sides of the micro-electrolysis tank 15. Ultrasonic oscillation is performed on the iron-carbon filler and sewage through the ultrasonic oscillation plates 17, thereby improving the fluidity between sewage and filler and the efficiency of contact exchange operations. A three-phase separator 19 is installed on the upper part of the channel steel 18. The wastewater, iron-carbon filler and air are fully contacted in three-dimensional directions from bottom to top, in a turbulent state, and momentum is transferred. The air and the waste gas generated by the reaction enter the subsequent gas treatment procedure through the waste gas pipe 21 after passing through the three-phase separator 19; an inclined tube sedimentation 20 is installed on the upper part of the three-phase separator 19 to further remove the iron-carbon filler. A micro-electrolysis water outlet trough 22 is installed on the upper part of the inclined tube sedimentation 20. The micro-electrolysis water outlet trough 22 is connected to the micro-electrolysis water outlet pipe 23, and the outlet water flows to the Fenton tank 24 by gravity.

[0056] At the lower part of the Fenton tank 24, there is a lower circulation pipe 31. The circulation pump 32 connected to the lower circulation pipe 31 transports the water in the Fenton tank 24 to the in-tank water distribution pipe 34 through the upper circulation pipe 33. The water distribution form in the Fenton tank 24 adopts a "rich" - shaped water distribution form in two groups, increasing the contact area with the reagent, enhancing the fluid disturbance, and promoting the reaction efficiency. The top of the Fenton tank 24 is connected to a hydrogen peroxide dosing tank 27. There is an 8% hydrogen peroxide solution in the hydrogen peroxide dosing tank 27. On the hydrogen peroxide dosing pipeline, there are a hydrogen peroxide metering pump 28, a hydrogen peroxide flowmeter 29, and a hydrogen peroxide electric ball valve 30. The hydrogen peroxide solution is added to the Fenton tank 24 through the hydrogen peroxide metering pump 28. The flow of hydrogen peroxide is detected by the hydrogen peroxide flowmeter 29. The hydrogen peroxide electric ball valve 30 is controlled by DCS to increase or decrease the dosing amount of hydrogen peroxide. A COD meter 25 is installed on the top of the Fenton tank 24. When the COD value in the Fenton tank 24 is higher than the set value, through the program set by DCS, the upper circulation pipe electric ball valve 36 is closed, and the reflux pipe electric ball valve 35 is opened. The wastewater in the Fenton tank 24 is transported to the micro - electrolysis inlet pipe 13 through the reflux pipe 37. An ultraviolet photocatalyst 43 is installed on the reflux pipe 37. The ultraviolet photocatalyst 43 can promote the decomposition of small - molecule organic substances, thereby improving the COD degradation efficiency. Through the promotion of the ultraviolet photocatalyst, the transformation of metal elements in the wastewater is promoted, and the Fenton tank 24 uses ultraviolet irradiation to promote the transformation of Fe 3+ / Fe 2+ transformation, reducing the dosing amount of Fe 2+ and the generation amount of iron sludge; A Fenton tank liquid level gauge 26 is installed at the upper part of the Fenton tank 24. The Fenton tank liquid level gauge 26 is linked with the circulation pump 32. According to the liquid level height of the Fenton tank 24, the start and stop of the circulation pump 32 are controlled. When the liquid level is lower than the designed low water level, the circulation pump 32 is automatically closed through DCS control. When the liquid level is higher than the designed high water level, the circulation pump 32 is automatically started through DCS control; When the COD value is lower than the set value, through the program set by DCS, the upper circulation pipe electric ball valve 36 and the Fenton tank outlet pipe electric ball valve 62 are opened, and the reflux pipe electric ball valve 35 is closed. The wastewater flows by gravity through the Fenton outlet pipe 38 to the neutralization tank 39.

[0057] The neutralization tank 39 is divided into three compartments. A paddle stirring device 41 is installed on the top of the first compartment. A neutralization tank pH meter 40 is installed on the upper part of the first compartment. The top of the first compartment is connected to the liquid alkali dosing tank 9 through a pipeline. A liquid alkali pneumatic regulating valve 2 44 is provided on the liquid alkali dosing pipeline. The amount of liquid alkali added is controlled by the liquid alkali pneumatic regulating valve 2 44. The reaction water in the first compartment flows to the second compartment by gravity. A frame mixer 42 is installed on the top of the second compartment. The top of the second compartment is connected to the PAC dosing tank 45 through a pipeline. A PAC dosing pipeline is provided with a PAC metering pump 46, a PAC dosing flow meter 47 and a PAC electric ball valve 48. There is 5% PAC solution in the PAC dosing tank 45, which is added to the second compartment of the neutralization tank through the PAC metering pump 46. The flow of the PAC solution is detected by the PAC dosing flow meter 47 and the DCS is used. Control the PAC electric ball valve 48 to increase or decrease the PAC dosage; the reaction water from the second compartment flows by gravity to the third compartment. A frame mixer 42 is installed on the top of the third compartment. The top of the second compartment is connected to the PAM (anion) dosing tank 49 through a pipeline. The PAM (anion) dosing pipeline is provided with a PAM (anion) metering pump 50, a PAM (anion) dosing flowmeter 51 and a PAM (anion) electric ball valve 52. There is 0.5% PAM (anion) solution in the PAM (anion) dosing tank 49, which is added to the third compartment of the neutralization tank through the PAM (anion) metering pump 50. The flow rate of the PAM (anion) solution is detected by the PAM (anion) dosing flowmeter 51. The PAM (anion) electric ball valve 52 is controlled by the DCS to increase or decrease the PAM (anion) dosage. The water from the neutralization tank 39 flows by gravity to the secondary sedimentation tank 54.

[0058] A central tube 55 and a sludge hopper 56 are provided inside the secondary sedimentation tank 54. A secondary sedimentation tank outlet trough 57 is provided on the top of the secondary sedimentation tank 54. A secondary sedimentation tank outlet pipe 58 is provided at the secondary sedimentation tank outlet trough 57. A sludge outlet pipe 59 is provided at the bottom of the secondary sedimentation tank 54. A secondary sedimentation tank sludge pump 60 is provided outside the secondary sedimentation tank 54. The sludge inlet end of the secondary sedimentation tank sludge pump 60 is connected to the sludge outlet pipe 59. The effluent from the neutralization tank 39 flows through the secondary sedimentation tank inlet pipe 53 to the central tube 55 in the secondary sedimentation tank. The wastewater flows from the secondary sedimentation tank outlet trough 57 and the secondary sedimentation tank outlet pipe 58 to the subsequent biochemical treatment process. The side wall angle of the sludge hopper 56 is set at 45°. The suspended matter in the water is removed by coagulation and sedimentation. The sludge is transported to the subsequent physical and chemical sludge tank through the sludge outlet pipe 59 by the sludge pump 60.

[0059] In one embodiment, a pretreatment method for pesticide wastewater with full-process control employs the pretreatment device for pesticide wastewater with full-process control, and the steps are as follows:

[0060] S1: The pesticide wastewater to be treated enters pH adjustment tank 1, where sulfuric acid and liquid alkali are added under DCS control to adjust the pH value of the wastewater to between 3 and 4;

[0061] S2: The pH-adjusted wastewater and catalyst in the pH adjustment tank 1 enter the micro-electrolysis tank 15, where the iron-carbon filler and wastewater react. The reacted mixed liquid in the micro-electrolysis tank 15 passes through the three-phase separator 19 to separate the wastewater, iron-carbon filler, and exhaust gas into three phases. The wastewater passes through the inclined tube sedimentation 20 to remove the iron-carbon filler, and then flows out of the micro-electrolysis outlet pipe 23 by gravity into the Fenton tank 24. The iron-carbon filler returns to the reaction zone of the micro-electrolysis tank 15 by gravity sedimentation, and the exhaust gas is connected to the exhaust pipe network through the exhaust pipe 21.

[0062] S3: Hydrogen peroxide is added to the Fenton tank 24 to fully react with the wastewater. When the COD value is higher than the set value, the wastewater in the Fenton tank 24 is returned to the micro-electrolysis tank 15. When the COD value is lower than the set value, the wastewater in the Fenton tank 24 is transported to the neutralization tank 39.

[0063] S4: Liquid alkali is added to the neutralization tank 39 to adjust the pH value, and PAC solution and PAM (anionic) solution are added to the wastewater to which the liquid alkali is added, so that the generated fine colloids are precipitated to form larger flocs. The wastewater in the neutralization tank 39 is transported to the secondary sedimentation tank 54, and the suspended matter in the water is removed by coagulation and sedimentation, and the sludge is transported to the subsequent physicochemical sludge tank.

[0064] Example 1

[0065] At a pesticide factory, the main source of production wastewater in the workshop is reaction residues and reactor wash water. The COD concentration in the wastewater fluctuates between 2500 and 4500 mg / L. The pH of the wastewater is adjusted to between 3 and 4 in pH adjustment tank 1. The effluent from pH adjustment tank 1 is discharged to micro-electrolysis tank 15 with a hydraulic retention time of 60 minutes. The effluent from micro-electrolysis tank 15 then flows by gravity to Fenton tank 24, where it remains for 120 minutes. The hydrogen peroxide added is 30% concentrated at a dosage of 5 to 6 mL / L. A ferrous sulfate dosing device is also included in Fenton tank 24, allowing it to operate independently during downtime for maintenance. During tandem operation, the effluent from the iron-carbon micro-electrolysis device appears green, indicating a high concentration of iron ions. This eliminates the need for additional ferrous sulfate dosing in micro-electrolysis tank 15, saving on reagent dosage and reducing operating costs. The effluent from the micro-electrolysis tank 15 enters the neutralization tank 39, where the pH is adjusted to 7-8 with liquid alkali. The effluent then enters the secondary sedimentation tank 54 after coagulation and flocculation. The COD removal rate of the effluent from the secondary sedimentation tank 54 ranges from 41% to 52%. Table 1 shows the water quality indicators of the pretreated effluent from Example 1.

[0066] Table 1 Water quality indicators of pretreated effluent from Example 1

[0067]

[0068] Example 2

[0069] The high-concentration mixed wastewater generated during the production process of a pesticide production enterprise in Jiangsu Province was treated as follows:

[0070] The COD concentration of the wastewater fluctuates between 5500 and 8500 mg / L. The pH is adjusted between 3 and 4 in the pH adjustment tank 1. The wastewater is output to the micro-electrolysis tank 15, where the organic matter is reduced and the chlorinated organic matter removes chloride ions during the micro-electrolysis process, reducing biological toxicity. The COD value of the pesticide wastewater treated by the micro-electrolysis tank 15 will be reduced, and the large molecular organic matter will be decomposed into small molecular fragments, reducing the processing load of the subsequent treatment process. The iron-carbon volume ratio of the micro-electrolysis tank 15 is 1.2:1, and the hydraulic retention time is 2h. After micro-electrolysis, the wastewater contains Fe 2+ After H2O2 is added to the Fenton tank 24, Fenton oxidation is carried out; hydrogen peroxide is quantitatively added using the hydrogen peroxide metering pump 28 to improve the biodegradability of the wastewater and reduce the COD value of the wastewater. The hydraulic retention time in the Fenton tank 24 is 5 hours.

[0071] Wastewater from Fenton tank 24 enters neutralization tank 39. Alkali is first added to the neutralization tank using caustic soda metering pump 10 to adjust the pH of the wastewater to the optimal flocculation pH of 8-9, forming relatively stable flocs. Coagulant and flocculant are then added to the wastewater using PAC metering pump 46 and PAM (anionic) metering pump 50. Solid particles in the wastewater are removed using a coagulation sedimentation tank. The COD removal rate of the sedimentation tank effluent ranges from 42% to 49%. Table 2 shows the water quality indicators of the pretreated effluent from Example 2.

[0072] Table 2 Water quality indicators of pre-treated effluent from Example 2

[0073]

[0074] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, 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 should not be understood as limiting the present invention.

[0075] In the present invention, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; internal communication between two elements or interaction between two elements, unless otherwise specified. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0076] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.

Claims

1. A pretreatment device for full-process control of pesticide wastewater, characterized in that: include: A pH adjustment tank (1), a micro-electrolysis tank (15), a Fenton tank (24), a neutralization tank (39) and a secondary sedimentation tank (54) are sequentially connected by a plurality of pipes. A channel steel (18) is installed in the middle upper part of the micro-electrolysis tank (15). A guide baffle (16) is vertically connected to the middle part of the channel steel (18). The guide baffle (16) divides the inside of the micro-electrolysis tank (15) into two chambers. Ultrasonic oscillation plates (17) are provided on both sides of the inner wall of the micro-electrolysis tank (15). A three-phase separator (19) is installed on the upper part of the channel steel (18). An inclined tube sedimentation (20) is provided on the upper part of the three-phase separator (19). A micro-electrolysis water outlet tank (22) is provided on the upper part of the inclined tube sedimentation (20); A raw water inlet pipe (2) for chemical wastewater is provided on the upper portion of the pH regulating tank (1), a pH regulating tank stirring device (61) is fixedly installed on the top of the pH regulating tank (1), a pH regulating tank sewage lifting pump (12) is provided outside the pH regulating tank (1), a pH regulating tank outlet pipe (11) is provided at the bottom of the pH regulating tank (1), the pH regulating tank outlet pipe (11) is connected to the input end of the pH regulating tank sewage lifting pump (12), and the output end of the pH regulating tank sewage lifting pump (12) is connected to the micro-electrolysis tank (15) via a micro-electrolysis inlet pipe (13); The pH adjustment tank stirring device (61) includes a stirring motor (61-1) and a shaft (61-2), the stirring motor (61-1) is vertically arranged, the lower end of the stirring motor (61-1) is fixedly connected to the upper end of the shaft (61-2), the outer wall of the shaft (61-2) is fixedly connected with a spiral mixing agitator, the outer wall of the bottom of the shaft (61-2) is fixedly connected with a hinged opening turbine (61-5), the blades of the hinged opening turbine (61-5) are inclined at 45 degrees, the spiral mixing agitator includes an outer spiral belt (61-3) and an inner spiral belt (61-4), the outer spiral belt (61-3) rotates to push the wastewater from the upper and lower ends of the pH adjustment tank (1) to the middle section, and the inner spiral belt (61-4) rotates to push the wastewater from the middle section of the pH adjustment tank (1) to the upper and lower ends; The micro-electrolysis water inlet pipe (13) adopts an "E"-shaped water inlet, and water is simultaneously inletted into the upper, middle, and lower parts of the micro-electrolysis tank (15). The micro-electrolysis water inlet pipe (13) is connected to the iron powder automatic dosing device (14), and a check valve (63) is installed at the micro-electrolysis water inlet pipe (13).

2. A pretreatment device for full-process control of pesticide wastewater according to claim 1, characterized in that: The water inlet pipe at the lower part of the Fenton tank (24) is connected to the micro-electrolysis water outlet tank (22) through the micro-electrolysis water outlet pipe (23). A lower circulation pipe (31) is provided at the bottom of the Fenton tank (24). A circulation pump (32) is provided outside the Fenton tank (24). The lower circulation pipe (31) is connected to the input end of the circulation pump (32). The output end of the circulation pump (32) is connected to the upper circulation pipe (33) provided at the upper part of the Fenton tank (24) through a set pipeline. An electric ball valve (36) for the upper circulation pipe is provided on the upper circulation pipe (33). The output end of the circulation pump (32) is connected to the micro-electrolysis water inlet pipe (13) on the micro-electrolysis tank (15) through a set return pipe (37). A return pipe electric ball valve (35) is provided on the return pipe (37). A Fenton tank water outlet pipe (38) is provided at the upper part of the Fenton tank (24). The Fenton tank water outlet pipe (38) is communicated with the neutralization tank (39).

3. A pretreatment device for full-process control of pesticide wastewater according to claim 1, characterized in that: A paddle type stirring device (41) is installed in the neutralization tank (39). The water outlet of the neutralization tank (39) is communicated with the secondary sedimentation tank (54) through a water passing hole. A central cylinder (55) and a sludge hopper (56) are provided inside the secondary sedimentation tank (54). A secondary sedimentation tank water outlet tank (57) is provided at the top of the secondary sedimentation tank (54). A secondary sedimentation tank water outlet pipe (58) is provided at the secondary sedimentation tank water outlet tank (57). A sludge discharge pipe (59) is provided at the bottom of the secondary sedimentation tank (54). A secondary sedimentation tank sludge discharge pump (60) is provided outside the secondary sedimentation tank (54). The sludge inlet end of the secondary sedimentation tank sludge discharge pump (60) is connected to the sludge discharge pipe (59).

4. A pretreatment device for full-process control of pesticide wastewater according to claim 2, characterized in that: A water distribution pipe (34) connected to the upper circulation pipe (33) is provided inside the Fenton tank (24). The water distribution pipe (34) adopts a form of two groups of "丰" shaped water distribution. A hydrogen peroxide dosing tank (27) is connected to the top of the Fenton tank (24).

5. A pretreatment device for full-process control of pesticide wastewater according to claim 2, characterized in that: An ultraviolet photocatalyst (43) is provided on the return pipe (37).

6. A pretreatment device for full-process control of pesticide wastewater according to claim 2, characterized in that: A pH meter (3) for the pH adjustment tank and a liquid level meter (4) for the pH adjustment tank are installed at the upper part of the pH adjustment tank (1). There is a 10% sulfuric acid solution in the sulfuric acid dosing tank (7), which is added to the pH adjustment tank (1) through a sulfuric acid metering pump (8). A sulfuric acid pneumatic regulating valve (5) is provided on the sulfuric acid dosing pipeline. There is a 28% liquid alkali solution in the liquid alkali dosing tank (9), which is added to the pH adjustment tank (1) through a liquid alkali metering pump (10). A liquid alkali pneumatic regulating valve I (6) is provided on the liquid alkali dosing pipeline. The pH meter (3) for the pH adjustment tank, the liquid level meter (4) for the pH adjustment tank, the sulfuric acid pneumatic regulating valve (5), the liquid alkali pneumatic regulating valve I (6), the sulfuric acid metering pump (8) and the liquid alkali metering pump (10) are all electrically connected to the DCS controller.

7. A pretreatment method for the whole-process control of pesticide wastewater, using a pretreatment device for the whole-process control of pesticide wastewater as described in any one of claims 1-6, and the steps are as follows: S1: The pesticide wastewater to be treated enters the pH adjustment tank (1), and sulfuric acid and liquid alkali are added through DCS control to adjust the pH value of the wastewater between 3 and 4; S2: The wastewater and catalyst with adjusted pH in the pH adjustment tank (1) enter the micro-electrolysis tank (15), the iron-carbon filler and the wastewater react in the micro-electrolysis tank (15), and the mixed liquid after the reaction in the micro-electrolysis tank (15) is separated into three phases of wastewater, iron-carbon filler and waste gas through the three-phase separator (19). The wastewater is removed from the iron-carbon filler by the inclined tube sedimentation (20) and then discharged from the micro-electrolysis outlet pipe (23) into the Fenton tank (24) by gravity. The iron-carbon filler returns to the reaction zone of the micro-electrolysis tank (15) by gravity sedimentation, and the waste gas is connected to the waste gas network through the waste gas pipe (21); S3: hydrogen peroxide is added to the Fenton tank (24) to fully react with the wastewater. When the COD value is higher than the set value, the wastewater in the Fenton tank (24) is returned to the micro-electrolysis tank (15). When the COD value is lower than the set value, the wastewater in the Fenton tank (24) is transported to the neutralization tank (39); S4: Liquid alkali is added to the neutralization tank (39) to adjust the pH value. PAC solution and anionic PAM solution are added to the wastewater to which the liquid alkali is added, so that the generated fine colloids are precipitated to form larger flocs. The wastewater in the neutralization tank (39) is transported to the secondary sedimentation tank (54), and the suspended solids in the water are removed by coagulation and sedimentation, and the sludge is transported to the subsequent physicochemical sludge tank.

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