Device and method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology

Abstract

The application discloses a device and method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology, which comprises water inlet tanks, iron-carbon micro-electrolysis cells, hydrolysis acidification tanks, regulating and storing tanks, SNAD reaction tanks and water outlet tanks connected in sequence, the outlet of the water inlet tank is connected with the inlet of the iron-carbon micro-electrolysis cell through a first water inlet pump, and the outlet of the regulating and storing tank is connected with the inlet of the SNAD reaction tank through a second water inlet pump; the iron-carbon micro-electrolysis cell is filled with iron-carbon fillers, a first aeration device is arranged at the bottom of the iron-carbon micro-electrolysis cell, and the first aeration device is connected with a first air pump; a second aeration device is arranged at the bottom of the SNAD reaction tank, and the second aeration device is connected with a second air pump. The application can exhibit good nitrogen and carbon removal effects on the treatment of late-stage landfill leachate, and effectively solves the problems of high-concentration refractory organic matters and high-concentration ammonia nitrogen in the late-stage landfill leachate.

Description

Technical Field

[0001] This invention relates to the technical field of landfill leachate treatment, specifically to an apparatus and method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology. Background Technology

[0002] With the continuous advancement of urbanization in my country, the amount of urban domestic waste generated is also gradually increasing. Sanitary landfill is one of the main methods of urban waste treatment in my country. However, the landfill process generates a large amount of leachate, which is characterized by high concentrations of ammonia nitrogen, high concentrations of organic pollutants, and complex composition, posing a pollution risk to the soil and groundwater surrounding the landfill. This is especially true for late-stage leachate, which is leachate from landfills that have been used for more than ten years. Its biodegradability is extremely poor, making it difficult to treat to meet standards. The mainstream methods for treating leachate often employ anaerobic-aerobic two-stage A / O process and upflow anaerobic sludge blanket (UASB)-oxidation ditch-stabilization pond process. However, these processes often require high aeration energy consumption and large carbon source additions, and it is difficult to guarantee the effluent quality when treating late-stage leachate.

[0003] SNAD (Simultaneous Partial Nitrification, Anammox and Denitrification) technology couples ammonia nitrogen oxidation, anammox denitrification, and denitrification deep denitrification and carbon removal into a single reactor. While maintaining the low energy consumption and ease of operation of anammox, it also addresses the issue of the remaining 11.2% nitrate nitrogen in the anammox reaction through denitrification. This integrated reactor significantly reduces operating costs and tank volume, while achieving stable nitrogen and carbon removal effects. However, because the organic pollutants in late-stage landfill leachate are difficult to biodegrade, and the high biotoxicity of these organics slows down microbial growth and proliferation, applying SNAD technology to late-stage landfill leachate treatment often results in problems such as difficult reaction start-up, insufficient carbon source for denitrification, and unstable effects. Therefore, SNAD technology needs to be coupled with a suitable late-stage landfill leachate pretreatment process to shorten the reaction start-up time and simultaneously convert recalcitrant organic matter to provide a sufficient carbon source for the denitrification process. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide an apparatus and method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology. This apparatus can exhibit good denitrification and carbon removal effects in the treatment of late-stage landfill leachate, effectively solving the problem of difficult treatment of high concentrations of recalcitrant organic matter and high concentrations of ammonia nitrogen in late-stage landfill leachate.

[0005] To achieve the above objectives, the present invention provides an apparatus for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology. The apparatus comprises an inlet tank, an iron-carbon micro-electrolysis cell, a hydrolysis acidification cell, a regulating tank, an SNAD reaction tank, and an outlet tank connected in sequence. The outlet of the inlet tank is connected to the inlet at the bottom of the iron-carbon micro-electrolysis cell via a first inlet pump. The iron-carbon micro-electrolysis cell is positioned above the hydrolysis acidification cell, with its outlet located at its upper part and the inlet at its bottom. Liquid in the iron-carbon micro-electrolysis cell flows into the hydrolysis acidification cell by gravity. The outlet of the regulating tank is connected to the inlet of the SNAD reaction tank via a second inlet pump. The iron-carbon microelectrolysis cell is filled with iron-carbon packing material, and a first aeration device is provided at the bottom of the iron-carbon microelectrolysis cell, which is connected to a first air pump; a second aeration device is provided at the bottom of the SNAD reaction cell, which is connected to a second air pump.

[0006] Furthermore, the iron-carbon filler in the iron-carbon microelectrolysis cell is spherical or ellipsoidal, with a particle size of 2-3 cm, a porosity of not less than 65%, an iron-carbon ratio of 65%-85%, a filling ratio of 50%-55%, and an effective specific surface area of ​​350 m². 2 / m 3 ~400 m 2 / m 3 .

[0007] Furthermore, the hydrolysis acidification tank is equipped with a constant temperature control device; the SNAD reaction tank is equipped with a stirring device; the inlet of the SNAD reaction tank is equipped with a first solenoid valve, and the outlet of the SNAD reaction tank is equipped with a second solenoid valve.

[0008] Furthermore, the device for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology also includes a time control device, the signal output terminal of which is connected to the signal input terminals of the second water inlet pump, the second air pump, the stirring device, the first solenoid valve, and the second solenoid valve, respectively.

[0009] Furthermore, the iron-carbon microelectrolysis cell and the hydrolysis acidification cell are continuous flow reactors, and the SNAD reaction cell is a sequencing batch reactor.

[0010] The present invention also provides a method for treating late-stage landfill leachate using the above-mentioned device based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology, characterized by comprising the following steps: S1: Leachate from late-stage landfill is fed into the iron-carbon micro-electrolysis cell from the inlet tank via the first inlet pump. In the iron-carbon micro-electrolysis cell, oxygen is supplied by the first aeration device to convert recalcitrant organic matter and at the same time, a portion of ammonia nitrogen is converted into nitrite nitrogen to reduce ammonia nitrogen load. S2: The effluent from the iron-carbon micro-electrolysis cell flows into the hydrolysis acidification tank by gravity to hydrolyze the remaining large molecular organic matter in the water, while reducing the organic load. The effluent from the hydrolysis acidification tank flows into the regulating tank. S3: The water in the storage tank is pumped into the SNAD reaction tank through the second inlet pump for denitrification and carbon removal. The treated water is then discharged in compliance with standards.

[0011] Furthermore, in step S1, the iron-carbon microelectrolysis cell is a continuous flow CSTR reactor with a hydraulic retention time of 24-48h, the temperature inside the cell is controlled at room temperature, the pH of the influent is controlled at 7.5-9.0, the SS is less than 1000mg / L, the carbon-nitrogen ratio is less than 5:1, and the ammonia nitrogen concentration is less than the maximum nitrogen removal load of the SNAD reactor. The bottom of the iron-carbon micro-electrolysis cell is equipped with a first aeration device, which controls the flow rate at 0.15~0.20L / min and aerates through a diffusion aeration disc to control the dissolved oxygen in the cell to not exceed 1.0mg / L.

[0012] Furthermore, in step S2, the hydrolysis acidification tank is a continuous flow CSTR reactor with a hydraulic retention time of 24-48 hours. A constant temperature control device is installed in the tank, and the temperature inside the tank is controlled at 33±2℃. The sludge concentration in the tank is not less than 3000mg / L, and the ratio of the height of the static sludge layer to the height of the hydrolysis acidification tank is not less than 15%. The hydrolysis acidification tank is covered to ensure that the dissolved oxygen is below 0.2mg / L.

[0013] Further, in step S3, the SNAD reactor is a sequencing batch reactor (SBR) with a hydraulic retention time of 48-72 hours, a temperature controlled at room temperature, a sludge concentration of not less than 2000 mg / L, a height-to-diameter ratio of 3:1 to 5:1, and is covered to prevent light exposure; a stirring device is installed in the SNAD reactor with a rotation speed of 80-90 rpm / min; the volume exchange rate of the SNAD reactor is 50%-60%, and a time control device is installed in the reactor to adjust the start and stop of each device within the cycle.

[0014] Furthermore, in step S3, a second aeration device is provided at the bottom of the SNAD reactor, which aerates through a diffusion aeration disc, controls the flow rate at 0.20~0.40 L / min, and operates in an intermittent aeration mode. The aeration and aeration stop time is adjusted to maintain the dissolved oxygen in the tank at 0.2~0.4 mg / L, and the short-term shock of dissolved oxygen does not exceed 2.0 mg / L; the SNAD reactor contains one or more of ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, and denitrifying bacteria.

[0015] Compared with the prior art, the present invention has the following advantages: Firstly, the device for treating late-stage landfill leachate based on the iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology of this invention saves space, reagent consumption, and power consumption. The reaction is easy to start and can show good denitrification and carbon removal effects in the treatment of late-stage landfill leachate, effectively solving the problem of difficult treatment of high concentration of recalcitrant organic matter and high concentration of ammonia nitrogen in late-stage landfill leachate.

[0016] Secondly, when iron-carbon micro-electrolysis is used as a pretreatment method to treat late-stage landfill leachate in this invention, it can greatly reduce the toxic effects of highly biotoxic organic matter in late-stage landfill leachate on the functional microorganisms in the subsequent hydrolysis acidification tank and SNAD reactor. At the same time, it provides iron and ferrous ions for the subsequent process, ensuring the operation of hydrolysis acidification and the start-up of anaerobic ammonia oxidation in SNAD technology.

[0017] Thirdly, in this invention, the hydrolysis acidification tank can consume the dissolved oxygen of the upstream water, buffering the adverse effects of dissolved oxygen fluctuations in the effluent of the iron-carbon micro-electrolysis tank on the SNAD reactor. The iron ions contained therein can promote the hydrolysis acidification reaction, converting recalcitrant organic matter into easily biodegradable organic carbon sources through hydrolysis acidification, thus providing sufficient denitrification carbon sources for the SNAD reactor.

[0018] Fourth, in this invention, the SNAD reactor receives effluent containing ferric and ferrous ions from the hydrolysis acidification tank. Under the action of ferric and ferrous ions, the anaerobic ammonia oxidation process in the SNAD reactor is easy to start and operate stably. At the same time, the biodegradable organic carbon source converted in the hydrolysis acidification tank promotes the denitrification process in the SNAD reactor, resulting in good nitrogen and carbon removal effects.

[0019] Fifth, the method adopted in this invention combines the advantages of low energy consumption and low cost of SNAD technology, while solving the problems of difficulty in starting up, insufficient carbon source for denitrification, and unstable effect when the traditional SNAD technology is used to treat late-stage landfill leachate. It has achieved good denitrification and carbon removal effects and has broad application prospects. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a device for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology; Figure 2 This is a diagram illustrating the ammonia nitrogen removal effect in treating late-stage landfill leachate in an embodiment of the present invention. Figure 3 This is a diagram illustrating the total nitrogen removal effect of treating late-stage landfill leachate in an embodiment of the present invention; In the diagram: 1. Inlet tank; 2. Iron-carbon micro-electrolysis cell; 3. Hydrolysis acidification cell; 4. Regulating tank; 5. SNAD reaction cell; 6. Outlet tank; 7. First inlet pump; 8. Second inlet pump; 9. Iron-carbon packing material; 10. First aeration device; 11. First air pump; 12. Second aeration device; 13. Second air pump; 14. Constant temperature control device; 15. Stirring device; 16. First solenoid valve; 17. Second solenoid valve; 18. Time control device. Detailed Implementation

[0021] The following examples illustrate the implementation of the present invention in detail, but they do not constitute a limitation on the invention and are merely illustrative. Furthermore, the advantages of the present invention will become clearer and easier to understand by explaining them.

[0022] like Figure 1 The apparatus shown is for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology. It includes an inlet tank 1, an iron-carbon micro-electrolysis cell 2, a hydrolysis acidification cell 3, a regulating tank 4, an SNAD reaction tank 5, and an outlet tank 6, connected in sequence. The outlet of the inlet tank 1 is connected to the inlet at the bottom of the iron-carbon micro-electrolysis cell 2 via a first inlet pump 7. The iron-carbon micro-electrolysis cell 2 is positioned above the hydrolysis acidification cell 3, with its outlet located above it. The inlet of the hydrolysis acidification cell 3 is located at its bottom. The liquid in the iron-carbon micro-electrolysis cell 2 is discharged by gravity. The water flows into the hydrolysis acidification tank 3; the outlet of the regulating tank 4 is connected to the inlet of the SNAD reaction tank 5 through the second inlet pump 8; a constant temperature control device 14 is installed in the hydrolysis acidification tank 3; a stirring device 15 is installed in the SNAD reaction tank 5; a first solenoid valve 16 is installed at the inlet of the SNAD reaction tank 5, and a second solenoid valve 17 is installed at the outlet of the SNAD reaction tank 5; the signal output terminal of the time control device 18 is connected to the signal input terminals of the second inlet pump 8, the second air pump 13, the stirring device 15, the first solenoid valve 16, and the second solenoid valve 17, respectively.

[0023] The iron-carbon microelectrolysis cell 2 is filled with iron-carbon filler 9. The iron-carbon filler 9 in the iron-carbon microelectrolysis cell 2 is spherical or ellipsoidal, with a particle size of 2~3cm, a porosity of not less than 65%, an iron-carbon ratio of 65%~85%, a filling ratio of 50%~55%, and an effective specific surface area of ​​350m². 2 / m 3 ~400 m 2 / m 3 The bottom of the iron-carbon microelectrolysis cell 2 is equipped with a first aeration device 10, which is connected to a first air pump 11; the bottom of the SNAD reaction cell 5 is equipped with a second aeration device 12, which is connected to a second air pump 13. The iron-carbon microelectrolysis cell 2 and the hydrolysis acidification cell 3 are continuous flow reactors, while the SNAD reaction cell 5 is a sequencing batch reactor.

[0024] A method for treating late-stage landfill leachate using the aforementioned apparatus based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology, according to the present invention, includes the following steps: S1: Late-stage landfill leachate is introduced into the iron-carbon micro-electrolysis tank 2 from the inlet tank 1 via the first inlet pump 7. In the iron-carbon micro-electrolysis tank 2, oxygen is supplied through the first aeration device 10 to convert recalcitrant organic matter and convert some ammonia nitrogen into nitrite nitrogen, thereby reducing the ammonia nitrogen load. The iron-carbon micro-electrolysis tank 2 is a continuous flow CSTR reactor with a hydraulic retention time of 24-48h. The tank temperature is controlled at room temperature, the inlet pH is controlled at 7.5-9.0, SS is below 1000mg / L, the carbon-nitrogen ratio is below 5:1, and the ammonia nitrogen concentration is below the maximum nitrogen removal load of the SNAD reactor. The bottom of the iron-carbon micro-electrolysis tank 2 is equipped with the first aeration device 10, which controls the flow rate at 0.15-0.20L / min and aeration is carried out through a diffusion aeration disc to control the dissolved oxygen in the tank to not exceed 1.0mg / L.

[0025] S2: The effluent from the iron-carbon micro-electrolysis cell 2 is flowed into the hydrolysis acidification tank 3 by gravity to hydrolyze the remaining macromolecular organic matter in the water, while reducing the organic load. The effluent from the hydrolysis acidification tank flows into the regulating tank 4. The hydrolysis acidification tank 3 is a continuous flow CSTR reactor with a hydraulic retention time of 24-48h. A constant temperature control device is installed in the tank to control the temperature at 33±2℃. The sludge concentration in the tank is not less than 3000mg / L. The ratio of the height of the static sludge layer to the height of the hydrolysis acidification tank is not less than 15%. The hydrolysis acidification tank is covered to ensure that the dissolved oxygen is below 0.2mg / L.

[0026] S3: Water from the regulating tank 4 is pumped into the SNAD reactor 5 via the second inlet pump 8 for denitrification and carbon removal. The treated water meets discharge standards. The SNAD reactor 5 is a sequencing batch reactor (SBR) with a hydraulic retention time of 48-72 hours. The temperature is controlled at room temperature, and the sludge concentration in the tank is not less than 2000 mg / L. The height-to-diameter ratio of the SNAD reactor is 3:1 to 5:1, and it is covered to prevent light exposure. The SNAD reactor 5 is equipped with a stirring device with a rotation speed of 80-90 rpm. The volume exchange rate of the SNAD reactor 5 is 50%-60%. A timer device is installed in the tank to adjust the start and stop of each device within the cycle. The operating cycle is 24 hours, with 5 minutes of influent, 23.5 hours of operation, 15 minutes of sedimentation, and 10 minutes of effluent settling. The bottom of the SNAD reactor 5 is equipped with a second aeration device 12, which aerates the tank through a diffusion aeration disc. The flow rate is controlled at 0.20~0.40L / min, and the tank is operated in an intermittent aeration mode. The aeration and aeration stop time is adjusted to maintain the dissolved oxygen in the tank at 0.2~0.4mg / L, and the short-term shock of dissolved oxygen does not exceed 2.0mg / L. The SNAD reactor 5 contains one or more of ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, and denitrifying bacteria, with Nitrosomonas, Candidatus_Kuenenia and Candidatus_Brocadia being the main species.

[0027] Example: A method for treating late-stage landfill leachate using an apparatus based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology, wherein the apparatus employs, for example... Figure 1 As shown, the main structure consists of an iron-carbon micro-electrolysis cell 2, a hydrolysis acidification cell 3, a regulating tank 4, and an SNAD reaction cell 5. The bottom inlet of the iron-carbon micro-electrolysis cell 2 is connected to the inlet tank 1, and water is supplied to the iron-carbon micro-electrolysis cell 2 from the inlet tank 1 by the first inlet pump 7. The iron-carbon micro-electrolysis cell 2 is filled with iron-carbon packing material 9, which consists of ellipsoidal particles with a particle size of approximately 3 cm, a porosity of approximately 70%, an iron-carbon ratio of approximately 75%, a filling ratio of 50%, and an effective specific surface area of ​​350 m². 2 / m 3 A first aeration device 10 is installed in the tank, and a first air pump 11 continuously aerates the tank. The bottom inlet of the hydrolysis acidification tank 3 is connected to the upper outlet of the iron-carbon micro-electrolysis tank 2, and water is supplied from the iron-carbon micro-electrolysis tank 2 to the hydrolysis acidification tank 3 by gravity flow. A constant temperature control device 14 is arranged in the hydrolysis acidification tank 3. Activated sludge is inoculated into the tank, with an initial sludge concentration of 4000 mg / L after inoculation, and the height of the static sludge layer accounts for 30% of the height of the hydrolysis acidification tank. The regulating tank 4 receives the effluent from the upper outlet of the hydrolysis acidification tank 3 to regulate the balance of water volume before and after inoculation.

[0028] The SNAD reactor 5 has a height-to-diameter ratio of 5:1. Its bottom inlet is connected to the bottom outlet of the regulating tank 4. Water is supplied from the regulating tank 4 to the SNAD reactor 5 by the second inlet pump 8. The inlet and outlet are controlled by the first solenoid valve 16 and the second solenoid valve 17. The SNAD reactor 5 is equipped with a stirring device 15 with a rotation speed of 80~90 rpm / min. A second aeration device 12 is installed in the tank, which intermittently aerates the tank by an air pump. The aeration and aeration stop time is 1 hour each. The second inlet pump 8, the second air pump 13, the stirring device 15, the first solenoid valve 16, and the second solenoid valve 17 are controlled by a timer device 18, which operates on a 24-hour cycle. The tank is inoculated with activated sludge and anaerobic ammonia oxidation seed sludge at a ratio of 8:1, with an initial sludge concentration of 4000 mg / L after inoculation. The outlet in the middle of the SNAD reactor 5 is connected to the effluent tank 6, and the effluent enters the effluent tank 6 for discharge.

[0029] The specific steps of the method in this embodiment are as follows: S1: Late-stage landfill leachate is fed into iron-carbon micro-electrolysis tank 2 from inlet tank 1 via first inlet pump 7 to convert recalcitrant organic matter. At the same time, a portion of ammonia nitrogen is converted into nitrite nitrogen to reduce ammonia nitrogen load. The hydraulic retention time is controlled at 24h, the temperature is controlled at 25℃ (room temperature), the aeration flow rate is controlled at 0.18±0.02L / min, and the dissolved oxygen in the tank is maintained at 0.85mg / L. S2: The effluent from the iron-carbon micro-electrolysis cell 2 is flowed into the hydrolysis acidification cell 3 by gravity to hydrolyze the remaining macromolecular organic matter in the water, while reducing the organic load. The hydraulic retention time is controlled at 24 hours, the temperature is controlled at 33±2℃, and the dissolved oxygen in the cell is maintained below 0.1mg / L for a long time. The effluent from the hydrolysis acidification cell 3 flows into the regulating tank 4. S3: The water in the regulating tank 4 is introduced into the SNAD reaction tank 5 through the second inlet pump 8 for denitrification and carbon removal treatment. The temperature is controlled at 25℃ (room temperature), the aeration and aeration stop time are controlled at 1 hour, the aeration flow rate is controlled at 0.25±0.02mg / L, and the dissolved oxygen in the tank is controlled at 0.2~0.4mg / L. The operation mode is as follows: 5 minutes of water inlet, 23.5 hours of operation, 15 minutes of sedimentation, 10 minutes of water discharge and settling, with an operation cycle of 24 hours. The treated water meets the standards and is discharged into the outlet tank 6.

[0030] A landfill has been in operation for over 10 years. Its late-stage leachate has the following characteristics: ammonia nitrogen concentration of 803±52 mg / L, COD concentration of 797±39 mg / L, carbon-to-nitrogen ratio close to 1, pH of 8.16, and SS of 466 mg / L. The denitrification of this late-stage leachate after applying the device of this invention is as follows: Figure 2 and Figure 3As shown, the device was successfully started up and operated stably after 45 days using actual late-stage landfill leachate as influent, saving 100% of chemical consumption and about 40% of electricity consumption. The highest ammonia nitrogen removal rate was 98.2%, and the highest total nitrogen removal rate was 96.9%, and it was able to maintain long-term stable operation.

[0031] This invention relates to a device and method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology. The device utilizes iron-carbon micro-electrolysis technology to degrade organic pollutants while simultaneously converting large, recalcitrant organic molecules into smaller molecules, reducing the biotoxicity of late-stage landfill leachate and minimizing its toxic impact on functional microorganisms in subsequent hydrolysis acidification and SNAD technologies. This provides iron and ferrous ions for the operation of hydrolysis acidification and the initiation of anaerobic ammonia oxidation in SNAD. The hydrolysis acidification technology further converts the organic pollutants in the late-stage landfill leachate. Under the influence of iron ions in the effluent from the iron-carbon micro-electrolysis tank, the hydrolysis acidification effect is enhanced. The process promotes the growth of nitrogen and carbon, thereby improving the biodegradability of the water body. At the same time, it consumes dissolved oxygen in the iron-carbon micro-electrolysis cell, reducing its impact on the dissolved oxygen of the subsequent SNAD technology. SNAD technology is used for denitrification and carbon removal. Under the action of iron and ferrous ions generated by the iron-carbon micro-electrolysis technology in the upstream water, anaerobic ammonia oxidation is easily initiated, its activity is improved, and the treatment effect is stable. Denitrification is carried out using the biodegradable carbon source from the hydrolyzed and acidified late-stage landfill leachate, solving the problem of difficult removal of nitrate and nitrogen from the SNAD process effluent. The integrated SNAD equipment saves space, reduces energy consumption and operating costs, and achieves good pollution removal results.

[0032] The above are merely specific embodiments of the present invention. It should be noted that any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the protection scope of the present invention. Any other aspects not described in detail are prior art.

Claims

1. A method for treating late-stage landfill leachate based on iron-carbon micro-electrolysis-hydrolysis acidification coupled SNAD technology, characterized in that, The apparatus includes an inlet tank (1), an iron-carbon micro-electrolysis cell (2), a hydrolysis acidification cell (3), a storage tank (4), an SNAD reaction cell (5), and an outlet tank (6) connected in sequence. The outlet of the inlet tank (1) is connected to the inlet at the bottom of the iron-carbon micro-electrolysis cell (2) through a first inlet pump (7). The iron-carbon micro-electrolysis cell (2) is located above the hydrolysis acidification cell (3). The outlet of the iron-carbon micro-electrolysis cell (2) is located at its upper part, and the inlet of the hydrolysis acidification cell (3) is located at its bottom. The liquid in the iron-carbon micro-electrolysis cell (2) flows into the hydrolysis acidification cell (3) by gravity. The outlet of the storage tank (4) is connected to the inlet of the SNAD reaction cell (5) through a second inlet pump (8). The iron-carbon micro-electrolysis cell (2) is filled with iron-carbon filler (9), and a first aeration device (10) is provided at the bottom of the iron-carbon micro-electrolysis cell (2). The first aeration device (10) is connected to a first air pump (11); a second aeration device (12) is provided at the bottom of the SNAD reaction tank (5), and the second aeration device (12) is connected to a second air pump (13). The iron-carbon microelectrolysis cell (2) contains spherical or ellipsoidal iron-carbon filler (9) with a particle size of 2-3 cm, a porosity of not less than 65%, an iron-carbon ratio of 65%-85%, a filling ratio of 50%-55%, and an effective specific surface area of ​​350 m². 2 / m 3 ~400 m 2 / m 3 ; The hydrolysis acidification tank (3) is equipped with a constant temperature control device (14); the SNAD reaction tank (5) is equipped with a stirring device (15), and the height-to-diameter ratio of the SNAD reaction tank (5) is 3:1 to 5:1; the inlet of the SNAD reaction tank (5) is equipped with a first solenoid valve (16), and the outlet of the SNAD reaction tank (5) is equipped with a second solenoid valve (17). It also includes a time control device (18), the signal output terminal of which is connected to the signal input terminals of the second water pump (8), the second air pump (13), the stirring device (15), the first solenoid valve (16) and the second solenoid valve (17), respectively. The iron-carbon microelectrolysis cell (2) and the hydrolysis acidification cell (3) are continuous flow reactors, and the SNAD reaction cell (5) is a sequencing batch reactor; the method includes the following steps: S1: Late-stage landfill leachate is fed into the iron-carbon micro-electrolysis cell (2) through the inlet tank (1) via the first inlet pump (7). In the iron-carbon micro-electrolysis cell (2), oxygen is supplied by the first aeration device (10) to convert recalcitrant organic matter. At the same time, a portion of ammonia nitrogen is converted into nitrite nitrogen to reduce the ammonia nitrogen load. The pH of the inlet water of the iron-carbon micro-electrolysis cell (2) is controlled at 7.5~9.0, SS is less than 1000mg / L, and the carbon-nitrogen ratio is less than 5:

1. S2: The effluent from the iron-carbon micro-electrolysis cell (2) is flowed into the hydrolysis acidification cell (3) by gravity to hydrolyze the remaining macromolecular organic matter in the water and reduce the organic load. The effluent from the hydrolysis acidification cell flows into the regulating tank (4). The hydrolysis acidification cell (3) is a continuous flow CSTR reactor with a hydraulic retention time of 24-48h. A constant temperature control device is installed in the cell to control the temperature at 33±2℃. The sludge concentration in the cell is not less than 3000mg / L. The ratio of the height of the static sludge layer to the height of the hydrolysis acidification cell is not less than 15%. The hydrolysis acidification cell is covered to ensure that the dissolved oxygen is less than 0.2mg / L. S3: The water in the regulating tank (4) is fed into the SNAD reactor (5) via the second inlet pump (8) for denitrification and carbon removal. The treated water is discharged after meeting the standards. The SNAD reactor (5) is a sequencing batch reactor (SBR) and operates in an intermittent aeration mode. The aeration and aeration stop times are adjusted to maintain the dissolved oxygen in the tank at 0.2~0.4 mg / L and the volume exchange rate at 50%~60%. The hydraulic retention time of the SNAD reactor (5) is 48-72 h, and the temperature is controlled at room temperature. The sludge concentration inside the tank is not less than 2000 mg / L, and it is covered to avoid light. The stirring device (15) in the SNAD reactor (5) rotates at 80~90 rpm. The second aeration device (12) at the bottom of the SNAD reactor (5) aerates through a diffusion aeration disc, and the flow rate is controlled at 0.20~0.40 L / min. The short-term shock of dissolved oxygen is not higher than 2.0 mg / L. The SNAD reactor (5) contains one or more of ammonia oxidizing bacteria, anaerobic ammonia oxidizing bacteria, and denitrifying bacteria.

2. The method according to claim 1, characterized in that: In step S1, the iron-carbon microelectrolysis cell (2) is a continuous flow CSTR reactor with a hydraulic retention time of 24-48h and the temperature inside the cell is controlled at room temperature. The iron-carbon micro-electrolysis cell (2) is equipped with a first aeration device (10) at the bottom, which controls the flow rate at 0.15~0.20L / min and aerates through a diffusion aeration disc to control the dissolved oxygen in the cell to not exceed 1.0mg / L.

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