Membrane concentrated water treatment system for coal chemical wastewater

Abstract

The utility model provides a coal chemical industry wastewater membrane concentrated water treatment system which comprises a wastewater pretreatment system and an advanced oxidation system which are arranged in sequence, the wastewater pretreatment system comprises a hardness and fluorine removal dosing reaction tank, a sedimentation tank, a clear liquid tank and a tubular membrane device which are arranged in sequence, and calcium and magnesium ions, fluorine ions and suspended solids in membrane concentrated water are removed; the advanced oxidation system comprises an ozone oxidation device and a thin film diamond electrode electrocatalytic oxidation device, COD and ammonia nitrogen in the membrane concentrated water are removed through the advanced oxidation effect, the coal chemical industry wastewater membrane concentrated water treatment system can completely remove most organic pollutants difficult to degrade in the coal chemical industry wastewater membrane concentrated water, new impurities are not introduced, and the treatment effect is good. The method can effectively improve the quality of the crystallized salt produced in the subsequent quality and salt separation process, and greatly reduces the load and investment operation cost required by single system treatment through the combination of multiple advanced oxidation methods.

Description

Technical Field

[0001] This utility model belongs to the field of coal chemical wastewater treatment technology, specifically relating to a coal chemical wastewater membrane concentrate treatment system. Background Technology

[0002] Membrane concentrate treatment is the final step in achieving full-scale treatment and discharge of coal chemical wastewater. Coal chemical membrane concentrate, specifically the reverse osmosis concentrate produced by coal chemical wastewater recycling systems, can have a COD exceeding 1000 mg / L and a TDS reaching as high as 100 g / L. It also contains large amounts of recalcitrant organic matter, various salts, and heavy metals. Currently, the treatment of coal chemical concentrate mainly relies on two technologies: "membrane concentration + evaporation crystallization to prepare mixed salt" and "membrane separation + evaporation crystallization and fractional salt separation." However, the pollutants present in the membrane concentrate result in trace amounts of toxic substances and heavy metals in the mixed salt prepared by evaporation crystallization, requiring disposal as hazardous waste. Furthermore, the mixed salt disposal technology poses a secondary environmental pollution risk and fails to meet ecological and environmental protection requirements. Therefore, the treatment of membrane concentrate pollutants urgently needs to be addressed. While some highly efficient treatment technologies can achieve better environmental results, their high costs may impose significant economic pressure on enterprises. Utility Model Content

[0003] The purpose of this invention is to solve the problems of high cost and inability to reuse prepared salt in existing membrane concentrate treatment, and to provide a membrane concentrate treatment system for coal chemical wastewater.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a coal chemical wastewater membrane concentrate treatment system, comprising: a wastewater pretreatment system and an advanced oxidation system;

[0005] The wastewater pretreatment system includes a hardness and fluoride removal dosing reaction tank, a sedimentation tank, a clear liquid tank, and a tubular membrane system. The hardness and fluoride removal dosing reaction tank, sedimentation tank, clear liquid tank, and tubular membrane system are connected in sequence to remove calcium and magnesium ions, fluoride ions, and suspended solids from the membrane concentrate.

[0006] The tubular membrane system is connected to the advanced oxidation system via a first product water tank;

[0007] The advanced oxidation system includes an ozone oxidation device and an electrocatalytic oxidation device. The ozone oxidation device is connected to the electrocatalytic oxidation device through a second product water tank and is used to completely mineralize organic matter in the membrane concentrate.

[0008] Furthermore, the hardening and defluorination dosing reaction tank includes a first reaction zone, a second reaction zone, and a third reaction zone. The bottom of the first reaction zone is connected to the second reaction zone, the bottom of the second reaction zone is connected to the third reaction zone, and the upper part of the third reaction zone is connected to the sedimentation tank through a pipe.

[0009] Furthermore, the sedimentation tank is connected to the clear liquid tank via an overflow weir, and the bottom pipe of the clear liquid tank is connected to the inlet of the inlet pump of the tubular membrane system.

[0010] Furthermore, a NaOH solution dosing tube is provided at the top of the first reaction zone, a Na2CO3 solution and PAC dosing tube is provided at the top of the second reaction zone, and a PAM dosing tube is provided at the top of the third reaction zone. Stirrers are provided inside the first, second, and third reaction zones.

[0011] Furthermore, the upper part of one side of the first reaction zone is connected to the outlet of the raw water pump, which is used to send the membrane concentrate into the first reaction zone.

[0012] Furthermore, the ozone oxidation device includes: a gas-water mixing device, an ozone generating device, and an ozone reactor;

[0013] One end of the gas-water mixing device is connected to the ozone generator and the first product water tank, and is used to mix the wastewater flowing out of the first product water tank with the ozone gas generated by the ozone generator and send it into the ozone reactor. The other end of the gas-water mixing device is connected to the ozone reactor. The upper part of the ozone reactor is connected to the second product water tank through the water outlet pipe. A side circulation pipe is provided on one side of the ozone reactor, and the side circulation pipe is connected to one end of the gas-water mixing device.

[0014] Furthermore, the gas-water mixing device is a multiphase flow mixing pump, and the ozone reactor is equipped with a dissolved gas release device at the bottom.

[0015] Furthermore, the electrocatalytic oxidation device includes a water inlet pump, an electrolytic reaction tank, and an electrolytic power supply;

[0016] The inlet of the water pump is connected to the second water production tank, the outlet of the water pump is connected to the bottom of the electrolytic reaction tank, the circulation port on the side of the electrolytic reaction tank is connected to the inlet of the water pump through a pipe, and the electrolytic power supply is connected to the electrode plate in the electrolytic reaction tank through a copper busbar.

[0017] Furthermore, the cathode plate in the electrolytic reaction cell is made of titanium electrode, and the anode plate in the electrolytic reaction cell is made of thin-film diamond electrode.

[0018] Furthermore, the number of anode plates is N, where N≥1, the number of cathode plates is N+1, and the anode plates and cathode plates are arranged alternately with a distance of 1cm between them.

[0019] Beneficial effects: In this invention, the pretreatment process combined with ozone oxidation and thin-film diamond electrode electrocatalytic oxidation can completely oxidize most of the heavy metals and organic matter in the membrane concentrate, solving the problem of pollutants in the subsequent salt production products. At the same time, the pre-ozone treatment reduces the amount of electrodes used in the electrocatalytic unit, greatly reducing investment costs. Furthermore, the post-treatment with thin-film diamond electrode electrocatalytic oxidation ensures the system's treatment effect and lays a solid foundation for subsequent water and salt treatment. The application of the pretreatment system effectively protects the electrode plates, largely preventing scaling and corrosion, and ensuring long-term stable operation of the system. Attached Figure Description

[0020] Figure 1 This is a process flow diagram of the present invention.

[0021] Figure 2 This is a process equipment diagram of this utility model.

[0022] In the diagram: 1. First reaction zone, 2. Second reaction zone, 3. Third reaction zone, 4. Sedimentation tank, 5. Clear liquid tank, 6. Tubular membrane system, 7. First product water tank, 8. Second product water tank, 9. Gas-water mixing device, 10. Oxygen generator, 11. Ozone reactor, 12. Inlet pump, 13. Electrolysis reaction tank, 14. Raw water pump. Detailed Implementation

[0023] The present invention will be further explained below with reference to the accompanying drawings.

[0024] like Figure 1 As shown, this utility model provides a membrane concentrate treatment system for coal chemical wastewater, including: a wastewater pretreatment system and an advanced oxidation system.

[0025] The wastewater pretreatment system includes a hardening and defluoridation dosing reaction tank, a sedimentation tank 4, a clear liquid tank 5, and a tubular membrane system 6. The hardening and defluoridation dosing reaction tank, sedimentation tank 4, clear liquid tank 5, and tubular membrane system 6 are connected in sequence to remove calcium and magnesium ions, fluoride ions, and suspended solids from the membrane concentrate.

[0026] The tubular membrane system 6 is connected to the advanced oxidation system via the first product water tank 7.

[0027] The advanced oxidation system includes an ozone oxidation unit and an electrocatalytic oxidation unit. The ozone oxidation unit is connected to the electrocatalytic oxidation unit through a second product water tank 8, and is used to completely oxidize the organic matter in the membrane concentrate.

[0028] like Figure 2As shown, the hardening and defluorination dosing reaction tank includes a first reaction zone 1, a second reaction zone 2, and a third reaction zone 3. The bottom of the first reaction zone 1 is connected to the second reaction zone 2, the bottom of the second reaction zone 2 is connected to the third reaction zone 3, and the upper part of the third reaction zone 3 is connected to the sedimentation tank 4 through a pipe. The top of the first reaction zone 1 is equipped with a NaOH solution dosing pipe, the top of the second reaction zone 2 is equipped with a Na2CO3 solution and PAC dosing pipe, and the top of the third reaction zone 3 is equipped with a PAM dosing pipe. A stirrer is installed inside the first reaction zone 1, the second reaction zone 2, and the third reaction zone 3. The upper part of one side of the first reaction zone 1 is connected to the outlet of the raw water pump 14, which is used to send the membrane concentrate into the first reaction zone 1.

[0029] Sedimentation tank 4 is connected to clear liquid tank 5 via an overflow weir, and the bottom pipe of clear liquid tank 5 is connected to the inlet of the inlet pump of tubular membrane system 6.

[0030] In this embodiment, the membrane concentrate is pumped into the first reaction zone 1 by the raw water pump 14. After coagulation reaction in the first reaction zone 1, the second reaction zone 2 and the third reaction zone 3, the water enters the sedimentation tank 4 to remove calcium and magnesium ions and fluoride ions from the raw water. The supernatant overflows into the clear liquid tank 5. The clear water in the clear liquid tank 5 enters the tubular membrane system 6 for further treatment to remove suspended solids. The permeate from the tubular membrane system 6 enters the first permeate tank 7.

[0031] The ozone oxidation device includes: a gas-water mixing device 9, an ozone generator 10, and an ozone reactor 11. One end of the gas-water mixing device 9 is connected to the ozone generator 10 and the first product water tank 7, and is used to mix the wastewater flowing out of the first product water tank 7 with the ozone gas generated by the ozone generator 10 and send it into the ozone reactor 11. The other end of the gas-water mixing device 9 is connected to the ozone reactor 11. The upper part of the ozone reactor 11 is connected to the second product water tank 8 through an outlet pipe, and a side circulation pipe is provided on one side of the ozone reactor 11. The side circulation pipe is connected to one end of the gas-water mixing device 9. The ozone oxidation device oxidizes some organic matter and decolorizes the wastewater through ozone oxidation. The gas-water mixing device 9 is a multiphase flow mixing pump. The ozone gas is generated by the ozone generator 10. The wastewater flowing out of the first product water tank 7 is mixed with the ozone gas through the multiphase flow mixing pump and enters the ozone reactor 11. The bottom of the ozone reactor 11 is equipped with a dissolved gas release device to improve the ozone utilization rate and ensure that the ozone fully oxidizes the membrane concentrate.

[0032] The electrocatalytic oxidation device includes a water inlet pump 12, an electrolytic reaction tank 13, and an electrolytic power supply. The inlet of the water inlet pump 12 is connected to the second product water tank 8, and the outlet of the water inlet pump 12 is connected to the bottom of the electrolytic reaction tank 13. The circulation port on the side of the electrolytic reaction tank 13 is connected to the inlet of the water inlet pump 12 via a pipe. The electrolytic power supply is connected to the electrode plates in the electrolytic reaction tank 13 via copper busbars. The positive electrode of the electrolytic power supply is connected to the anode plate via a copper plate, and the negative electrode of the electrolytic power supply is connected to the anode plate of the electrode plate via a copper plate. The electrocatalytic oxidation device can catalytically oxidize ozone-oxidized products. The organic matter in the concentrate after ozone oxidation is completely oxidized, meeting discharge requirements. The electrolysis reactor 13 is also equipped with an overflow weir. The cathode plate in the electrolysis reactor 13 uses titanium electrodes, and the anode plate uses thin-film diamond electrodes, which have higher oxidation-reduction potentials and can completely oxidize organic pollutants in the concentrate after ozone oxidation. The number of anode plates is N, where N≥1, and the number of cathode plates is N+1. Both anode and cathode plates are arranged alternately with a spacing of 1 cm. During electrocatalysis, the current density is 60~80 mA / cm². 2 .

[0033] The specific working process of this utility model is as follows:

[0034] The membrane concentrate is pumped to the inlet of the wastewater pretreatment system via the raw water pump 14. It then passes through the first reaction zone 1, where 30% NaOH solution and 25% Na2CO3 solution are added through pipes to precipitate calcium and magnesium ions. Subsequently, the wastewater flows through the bottom to the second reaction zone 2, where 15% PAC solution is added through pipes to precipitate fluoride ions and other heavy metal ions. The wastewater then flows through the bottom to the third reaction zone 3, where 1.5‰ PAM solution is added through pipes for coagulation. Agitators are installed inside the first, second, and third reaction zones 1 and 2. After coagulation, the water enters the sedimentation tank 4 to remove calcium and magnesium ions, fluoride ions, and heavy metals from the raw water. The supernatant overflows into the clear liquid tank 5, where the clear water enters the tubular membrane system 6 for further treatment to remove suspended solids. The permeate from the tubular membrane system 6 enters the first permeate tank 7. After pretreatment, the concentrated membrane water flows out from the first product water tank 7 and mixes with the ozone gas through a multiphase flow mixing pump before entering the ozone reactor 11 from the bottom. The ozone reactor 11 is equipped with a dissolved gas release device at the bottom to improve ozone utilization and ensure that ozone fully oxidizes the wastewater. The upper outlet pipe of the ozone reactor 11 is connected to the second product water tank 8, and a side circulation pipe is provided below the outlet to connect to the water inlet of the gas-water mixing pump and mix with the incoming water.

[0035] The outlet of the second water tank 8 is connected to the inlet of the water pump 12. The outlet of the water pump is connected to the bottom of the electrolysis reaction tank 13. The side of the electrolysis reaction tank 13 is provided with a circulation port, which is connected to the inlet of the water pump 12 via the water inlet pipe. The electrolysis reaction tank 13 is provided with an overflow weir inside, and the water is discharged after meeting the standards. Example

[0036] The secondary membrane concentrate from a coal-to-methanol plant in Xinjiang has a COD of 399.4 mg / L, an ammonia nitrogen concentration of 215.2 mg / L, and a calcium concentration of... 2+ The concentration was 1011.86 mg / L, Mg 2+ With a concentration of 113.25 mg / L and a color intensity of 400 times, after pretreatment, Ca... 2+ The concentration was 12.4 mg / L, Mg 2+ Concentration 2.56 mg / L. Influent flow rate 1 m³ / h. 3 / h, ozone concentration is 60g / Nm 3 The gas volume is 4m³ 3 The reaction time was 7 minutes, and the COD after the reaction was 285.6 mg / L, with a color increase of 10 times. A thin-film diamond electrode was used as the anode, and titanium-plated 304 stainless steel was used as the cathode. The anode plate area was 5 m², the distance between the anode and cathode plates was 1 cm, and the current density was 60 mA / cm². 2 The electrolysis time was 1 hour. After 30 minutes of reaction, the COD of the effluent was 82.64 mg / L. After 1 hour of reaction, the COD of the effluent was 26.64 mg / L and the ammonia nitrogen was 0.95 mg / L.

[0037] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A coal chemical wastewater membrane concentrated water treatment system, characterized in that, include: Wastewater pretreatment systems and advanced oxidation systems; The wastewater pretreatment system includes a hardening and defluoridation dosing reaction tank, a sedimentation tank (4), a clear liquid tank (5), and a tubular membrane system (6). The hardening and defluoridation dosing reaction tank, sedimentation tank (4), clear liquid tank (5), and tubular membrane system (6) are connected in sequence to remove calcium and magnesium ions, fluoride ions, and suspended solids from the membrane concentrate. The tubular membrane system (6) is connected to the advanced oxidation system via the first product water tank (7); The advanced oxidation system includes an ozone oxidation device and an electrocatalytic oxidation device. The ozone oxidation device is connected to the electrocatalytic oxidation device through a second product water tank (8) and is used to completely mineralize organic matter in the membrane concentrate.

2. The coal chemical wastewater membrane concentrated water treatment system according to claim 1, characterized in that, The hardening and defluorination dosing reaction tank includes a first reaction zone (1), a second reaction zone (2) and a third reaction zone (3). The bottom of the first reaction zone (1) is connected to the second reaction zone (2), the bottom of the second reaction zone (2) is connected to the third reaction zone (3), and the upper part of the third reaction zone (3) is connected to the sedimentation tank (4) through a pipe.

3. The coal chemical wastewater membrane concentrated water treatment system according to claim 2, characterized in that, The sedimentation tank (4) is connected to the clear liquid tank (5) through an overflow weir, and the bottom pipe of the clear liquid tank (5) is connected to the inlet of the water pump of the tubular membrane system (6).

4. The coal chemical wastewater membrane concentrated water treatment system according to claim 2, characterized in that, The top of the first reaction zone (1) is provided with a NaOH solution dosing tube, the top of the second reaction zone (2) is provided with a Na2CO3 solution and a PAC dosing tube, the top of the third reaction zone (3) is provided with a PAM dosing tube, and a stirrer is provided inside the first reaction zone (1), the second reaction zone (2) and the third reaction zone (3).

5. The coal chemical wastewater membrane concentrated water treatment system according to claim 2, characterized in that, The upper part of one side of the first reaction zone (1) is connected to the outlet of the raw water pump (14), which is used to send the membrane concentrate into the first reaction zone (1).

6. The coal chemical wastewater membrane concentrated water treatment system according to claim 1, characterized in that, The ozone oxidation device includes: a gas-water mixing device (9), an ozone generating device (10), and an ozone reactor (11). One end of the gas-water mixing device (9) is connected to the ozone generator (10) and the first water production tank (7) to mix the wastewater flowing out of the first water production tank (7) with the ozone gas generated by the ozone generator (10) and send it into the ozone reactor (11). The other end of the gas-water mixing device (9) is connected to the ozone reactor (11). The upper part of the ozone reactor (11) is connected to the second water production tank (8) through the water outlet pipe. A side circulation pipeline is provided on one side of the ozone reactor (11), and the side circulation pipeline is connected to one end of the gas-water mixing device (9).

7. The coal chemical wastewater membrane concentrated water treatment system according to claim 6, characterized in that, The gas-water mixing device (9) is a multiphase flow mixing pump, and the ozone reactor (11) is equipped with a dissolved gas release device at the bottom.

8. The coal chemical wastewater membrane concentrated water treatment system according to claim 1, characterized in that, The electrocatalytic oxidation device includes a water inlet pump (12), an electrolytic reaction tank (13), and an electrolytic power supply; The inlet of the water pump (12) is connected to the second water production tank (8), the outlet of the water pump (12) is connected to the bottom of the electrolytic reaction tank (13), the circulation port on the side of the electrolytic reaction tank (13) is connected to the inlet of the water pump (12) through a pipe, and the electrolytic power supply is connected to the electrode plate in the electrolytic reaction tank (13) through a copper busbar.

9. The coal chemical wastewater membrane concentrated water treatment system according to claim 8, characterized in that, The cathode plate in the electrolytic reaction cell (13) is made of titanium electrode, and the anode plate in the electrolytic reaction cell (13) is made of thin-film diamond electrode.

10. The coal chemical wastewater membrane concentrated water treatment system according to claim 9, characterized in that, The number of anode plates is N, where N≥1, and the number of cathode plates is N+1. The anode plates and cathode plates are arranged alternately, and the distance between them is 1cm.

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