A system for reducing total nitrogen removal from leachate-produced water

Abstract

The present invention discloses a leachate water production and total nitrogen removal system, which overcomes the problem that the removal rate of nitrogen in sewage in the prior art is not high enough and cannot meet the emission standards, and includes: a primary treatment system for filtering out larger particles in the leachate and decomposing organic matter in the leachate; a nitrogen removal system for multi-stage circulation vertical partition multiplication biological nitrogen removal; a nitrification liquid reflux system for achieving precise control of the nitrogen removal system; a carbon source addition system for supplementing carbon sources to the nitrogen removal system and the organic matter removal system; and a discharge device for discharging the leachate treated by the nitrogen removal system. A high degree of decarbonization of the garbage leachate is achieved, so that the total nitrogen in the garbage leachate meets the emission standards; it is fully automatic and unmanned, reducing the operating cost and labor cost of leachate treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of garbage treatment equipment, and particularly relates to a system for reducing total nitrogen removal from leachate produced water. Background Art

[0002] The rapid increase in municipal domestic waste is one of the prominent environmental problems faced by China. As a harmless way of treating domestic waste, waste incineration power generation has attracted great attention from the state. The quality of leachate is complex, with high pollutant concentrations and difficult to treat. Direct discharge will cause serious pollution to water sources and soil. For the purpose of environmental protection, it is essential to treat leachate. However, the quality of leachate is extremely complex and the pollutant concentration is high. When this water seeps through the waste with complex components, reactions such as decomposition, dissolution, and fermentation of the waste occur, resulting in a large amount of organic pollutants, nitrogen, phosphorus, and various heavy metal substances in the leachate. Therefore, the treatment of leachate has always been a worldwide problem.

[0003] With the improvement of national environmental protection requirements and the standardization of supervision, clear requirements have been put forward for the total nitrogen index of leachate discharged into urban sewers, not exceeding 70 mg / L. As a new sewage treatment method, the anaerobic ammonium oxidation process (ANAMMOX) has the advantages of low energy consumption, no need to add carbon source, low sludge production rate, and less greenhouse gas emissions. It can make ammonia nitrogen and nitrite nitrogen react under anaerobic conditions to achieve the purpose of nitrogen removal. The partial nitrification - anaerobic ammonium oxidation process (PN - ANAMMOX) can reduce the aeration demand by 63%, the carbon source demand by 100%, and the sludge production by 90%. However, the theoretical total nitrogen removal rate of the anaerobic ammonium oxidation process is about 89%, and 11% of the nitrogen remains in the form of nitrate nitrogen, which is difficult to meet the increasingly strict emission standards in China. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem that the nitrogen removal rate of removing nitrogen from sewage in the prior art is not high enough, and provide a system for reducing total nitrogen removal from leachate produced water, which realizes high - degree decarbonization of leachate, makes the total nitrogen of leachate meet the emission standards; operates automatically without human attendance, reducing the operation cost and labor cost of leachate treatment.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: including:

[0006] A primary treatment system for filtering out larger particles in the leachate and decomposing organic matter in the leachate;

[0007] A nitrogen removal system for performing multi - stage cyclic vertical partition multiplication biological nitrogen removal;

[0008] A nitrification liquid reflux system for achieving precise control of the nitrogen removal system;

[0009] A carbon source dosing system for supplementing carbon sources to a denitrification system and an organic matter removal system;

[0010] An emission device for discharging the leachate after being treated by the denitrification system.

[0011] The primary treatment system, the denitrification system, and the emission device are connected in sequence. The carbon source dosing system is respectively connected to the denitrification system and the primary treatment system. The nitrification liquid reflux system is respectively connected to the denitrification system and the primary treatment system. The touch treatment system is connected to the emission device. The denitrification system can adopt a multi-stage circulating vertical partition doubling biological denitrification reactor for multi-stage circulating vertical partition doubling biological denitrification. The denitrified leachate is refluxed to the emission device for mud-water separation, and an external carbon source is added to the denitrification system. The nitrification liquid reflux system includes a flowmeter and a pipe valve system to achieve precise denitrification control; the carbon source dosing system can ensure that the total nitrogen in the effluent meets the standard continuously and stably. The present invention realizes high-degree decarbonization of landfill leachate, and operates fully automatically without human attendance. Personnel can be arranged for remote monitoring when needed, reducing the operation cost and labor cost of leachate treatment; and it has a simple structure, few equipment, low energy consumption, and little maintenance work.

[0012] Preferably, the denitrification system includes:

[0013] The first denitrification reaction unit is used to utilize nitrate and an external carbon source to achieve first-stage high-concentration denitrification through high-fold circulation;

[0014] The second denitrification reaction unit is used to utilize nitrate and an external carbon source to complete second-stage high-concentration denitrification;

[0015] The third denitrification reaction unit is used to utilize nitrate and an external carbon source to complete third-stage medium-concentration denitrification;

[0016] The fourth denitrification reaction unit is used to utilize nitrate and an external carbon source to complete fourth-stage low-concentration denitrification.

[0017] The first denitrification reaction unit, the second denitrification reaction unit, the third denitrification reaction unit, and the fourth denitrification reaction unit are connected in sequence. The nitrate comes from the nitrate in the leachate transported after being treated by the primary treatment equipment and the nitrate in the sludge reflux liquid of the denitrification equipment. Through multi-stage circulating vertical partition denitrification, the denitrification efficiency is further improved, and high-degree denitrification is achieved.

[0018] Preferably, the fourth denitrification reaction unit is further used to synchronously remove the remaining carbon source and realize the reflux of bacteria through gas reflux and liquid level control. The bacteria are effectively utilized, so that the organic matter in the leachate is decomposed thoroughly, and the denitrification effect is more remarkable.

[0019] Preferably, the primary treatment system includes:

[0020] A leachate treatment system for preliminarily treating leachate and separating aged sludge;

[0021] An organic matter removal system for degrading the organic matter in the leachate after removing the aged sludge into inorganic matter, realizing the preliminary treatment of the leachate and ensuring the stable operation of the subsequent treatment process.

[0022] Preferably, the leachate treatment system includes:

[0023] A regulating tank for removing larger particles in the leachate and transporting the treated leachate to a comprehensive tank;

[0024] A comprehensive tank for removing insoluble inorganic matter in the leachate transported from the regulating tank and transporting the treated leachate to a UASB reactor;

[0025] A UASB reactor for removing the aged sludge in the leachate transported from the comprehensive tank, transporting the leachate after removing the aged sludge to the organic matter removal system, and transporting the aged sludge to the discharge equipment.

[0026] Since the water quality and quantity of the leachate generated by garbage stacking vary greatly in different seasons and periods, it is introduced into the regulating tank to stay for a certain time, filter and precipitate to remove inorganic matters such as fiber filaments and sediment, and make the wastewater fully mixed in the tank through pre-aeration, and heat it to the anaerobic required temperature at the outlet of the regulating tank to ensure the stable operation of the subsequent treatment process. Before the wastewater enters the UASB reactor, it is pre-acidified in the comprehensive tank to hydrolyze the complex macromolecular organic matter into small molecule substances, and the sewage is pre-regulated in the comprehensive tank, which is beneficial to the stable operation of total nitrogen removal.

[0027] Preferably, the organic matter removal system includes an anoxic tank connected to the primary treatment system and several aerobic tanks connected in sequence, where the first aerobic tank is connected to the anoxic tank, and the last aerobic tank is respectively connected to the anoxic tank and the denitrification system.

[0028] A bypass is added at the end of the last aerobic tank and a flow meter and pipe valves are set, so as to lift the effluent of the last aerobic tank to the denitrification system.

[0029] Preferably, the discharge equipment includes:

[0030] An MBR tank for removing the remaining sludge in the leachate after denitrification, realizing the separation of mud and water, discharging the remaining sludge to the sludge thickening tank, and discharging the leachate after removing the remaining sludge to the nanofiltration system;

[0031] A nanofiltration system for concentrating and separating the sewage from the leachate after removing the remaining sludge;

[0032] The sludge thickening tank is used to reduce the moisture content of the aged sludge and the excess sludge, and reduce the volume of the aged sludge and the excess sludge.

[0033] The MBR tank is respectively connected to the denitrification system and the nanofiltration system of the sludge thickening tank, and the discharge equipment treats and discharges the leachate after denitrification.

[0034] Preferably, the denitrification system further includes a sludge reflux system for transporting the sludge in the denitrification process to the front end of the first denitrification reaction unit.

[0035] Continuously transport the sludge in the denitrification process to the front end of the first denitrification reaction unit to re-participate in the leachate treatment process. In this way, the lost sludge is continuously supplemented, the influent load is reduced, and the impact resistance of the reaction tank of the denitrification system is maximized. There is no need to set up an adjustment tank at the front end of the first denitrification reaction unit. In addition, a certain flow rate can be maintained through reflux to keep the sludge layer in a suspended state, and the extreme impact load is strong in a short time. The denitrification system operates at a high sludge concentration, and the mixed liquid reflux ratio is large, so that each unit has some advantages of plug flow type and complete mixing type, and the concentration gradient of pollutants in the whole process is small. Especially in the anoxic zone operating at a low load, the microorganisms in the activated sludge are in the endogenous respiration period, there will be no sludge bulking phenomenon, and the sludge production is low, saving investment and operating costs, and greatly reducing the workload of operation and management.

[0036] Therefore, the present invention has the following beneficial effects: 1. Through the denitrification system, high-degree decarbonization of the landfill leachate is achieved, and the total nitrogen of the landfill leachate reaches the discharge standard; 2. It has a unique sludge circulation route. Part of the activated sludge at the end of the vertical partition of the denitrification system flows back to the front end of the first denitrification reaction unit, and denitrification is very thorough in a long anoxic process, and the carbon source in the leachate is fully utilized, with high resource utilization rate; 3. It operates automatically without human attendance, reducing operating costs and labor costs; 4. Unnecessary links and equipment in the traditional leachate treatment process are removed, greatly reducing the energy consumption of the leachate treatment plant. Description of the Drawings

[0037] Figure 1 It is a schematic structural diagram of the total nitrogen removal system of the present invention.

[0038] Figure 2 It is a schematic structural diagram of the denitrification system in the present invention.

[0039] In the figure: 1. Leachate treatment system; 2. Regulation tank; 3. Comprehensive tank; 4. UASB reactor; 5. Organic matter removal system; 6. Anoxic tank; 7. First aerobic tank; 8. Second aerobic tank; 9. Third aerobic tank; 10. Fourth aerobic tank; 11. Denitrification system; 12. First denitrification unit; 13. Second denitrification unit; 14. Third denitrification unit; 15. Fourth denitrification unit; 16. Discharge equipment; 17. MBR tank; 18. Nanofiltration system; 19. Sludge thickening tank; 20. Carbon source dosing system; 21. Nitrification liquid reflux system. Specific implementation manner

[0040] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation manners:

[0041] Example 1:

[0042] This Example 1 is a total nitrogen removal system for leachate produced water. As Figure 1 shown, it includes a leachate treatment system 1, an organic matter removal system 2, a denitrification system 11, and a discharge device 16 that are connected in sequence. It also includes a carbon source dosing system 20 that is respectively connected to the denitrification system, the leachate treatment system, and the organic matter removal system, and a nitrification liquid reflux system 21 that is connected to the organic matter removal system. Among them, the leachate treatment system is used to preliminarily treat the leachate, separate the aged sludge, and discharge the aged sludge to the discharge device; the organic matter removal system is used to degrade the organic matter in the leachate after removing the aged sludge into inorganic substances; the denitrification system is used for multi-stage cyclic vertical partition multiplication biological denitrification; the nitrification liquid reflux system includes a flowmeter and a pipe valve system, which is used to achieve precise control of the denitrification system; the carbon source dosing system is used to supplement the carbon source for the denitrification system and the organic matter removal system to ensure that the total nitrogen in the effluent reaches the standard continuously and stably.

[0043] In this embodiment, the denitrification system can adopt a multi-stage cyclic vertical partition multiplication biological denitrification reactor for multi-stage cyclic vertical partition multiplication biological denitrification. The denitrified leachate is refluxed to the discharge device for mud-water separation, and an external carbon source is added to the denitrification system. The present invention realizes highly efficient decarbonization of landfill leachate, and operates fully automatically without human attendance. Personnel can be arranged for remote monitoring when needed, reducing the operation cost and labor cost of leachate treatment; and it has a simple structure, few equipment, low energy consumption, and little maintenance work.

[0044] In this embodiment:

[0045] The leachate treatment system includes an adjustment tank 2, a comprehensive tank 3, and a USAB reactor 4 connected in sequence. The USAB reactor 4 is respectively connected to an organic matter removal system and a discharge device. The adjustment tank is used to remove larger particles in the leachate and transport the treated leachate to the comprehensive tank. The comprehensive tank is used to remove insoluble inorganic substances in the leachate transported from the adjustment tank and transport the treated leachate to the UASB reactor. The UASB reactor is used to remove the aged sludge in the leachate transported from the comprehensive tank, transport the leachate after removing the aged sludge to the organic matter removal system, and transfer the aged sludge to the discharge device.

[0046] Specifically:

[0047] The untreated leachate first enters the adjustment tank. Since the water quality and quantity of the leachate generated by garbage stacking in different seasons and different periods fluctuate greatly, it is introduced into the adjustment tank to stay for a certain period of time, and inorganic substances such as fiber filaments and sediment are removed by filtration and precipitation. The wastewater is fully mixed in the tank through pre-aeration and heated to the anaerobic required temperature at the outlet of the adjustment tank to ensure the stable operation of the subsequent treatment process. Before the wastewater enters the UASB reactor, it is pre-acidified in the comprehensive tank to hydrolyze the complex macromolecular organic matter into small molecule substances, and the wastewater is pre-adjusted in the comprehensive tank, which is beneficial to the stable operation of total nitrogen removal.

[0048] Among them, the organic matter removal system includes an anoxic tank 6, a first aerobic tank 7, a second aerobic tank 8, a third aerobic tank 9, and a fourth aerobic tank 10 connected in sequence. The anoxic tank is respectively connected to the USAB reactor and the nitrification liquid reflux system. The fourth aerobic tank is respectively connected to the nitrification liquid reflux system and the nitrogen removal system. A bypass is also provided at the end of the terminal aerobic tank, and a flow meter and pipe valves are set, so as to lift the effluent of the terminal aerobic tank to the nitrogen removal system.

[0049] The nitrogen removal system is the core system of the present invention. In this embodiment, the nitrogen removal system uses an integrated multi-stage circulating vertical partitioned biological nitrogen removal reactor for multi-stage circulating vertical partitioned biological nitrogen removal. The nitrogen removal system is divided into 4-level nitrogen removal units, including a first nitrogen removal unit 12, a second 13, a third 14, and a fourth 15 connected in sequence. The first is also connected to the carbon source dosing system and the fourth aerobic tank. The fourth nitrogen removal unit is also connected to the discharge device. The first nitrogen removal reaction unit is used to utilize nitrate and the added carbon source to achieve high-concentration nitrogen removal in the first stage through high-fold circulation. The second nitrogen removal reaction unit is used to utilize nitrate and the added carbon source to complete high-concentration nitrogen removal in the second stage. The third nitrogen removal reaction unit is used to utilize nitrate and the added carbon source to complete medium-concentration nitrogen removal in the third stage. The fourth nitrogen removal reaction unit is used to utilize nitrate and the added carbon source to complete low-concentration nitrogen removal in the fourth stage, and is also used to synchronously remove the remaining carbon source, and realize the return of bacteria through gas reflux and liquid level control. The return of bacteria is as Figure 2As shown in the figure; there is also a sludge area inside the denitrification unit, which is used to store the sludge in the leachate separated during the operation of the denitrification unit.

[0050] The nitrate comes from the nitrate in the leachate transported after being treated by the primary treatment equipment and the nitrate in the sludge return liquid of the denitrification equipment. Through multi-stage circulating vertical partition denitrification, the denitrification efficiency is further improved, and high-level denitrification is achieved.

[0051] In this embodiment, the discharge equipment includes an MBR tank 15 connected to the fourth denitrification unit, a sludge thickening tank 19 and a nanofiltration system 18 connected to the MBR tank. The sludge thickening tank is also connected to the UASB reactor; the MBR tank is used to remove the remaining sludge in the leachate after denitrification, achieve mud-water separation, discharge the remaining sludge to the sludge thickening tank, and discharge the leachate after removing the remaining sludge to the nanofiltration system; the nanofiltration system is used to concentrate and separate the sewage from the leachate after removing the remaining sludge. The sludge thickening tank is used to reduce the moisture content of the aged sludge and the remaining sludge, and reduce the volume of the aged sludge and the remaining sludge.

[0052] In the present invention, a bypass is added at the end of the fourth aerobic tank, and a flow meter and pipe valves are set. The effluent of the fourth aerobic tank is lifted to the denitrification system (integrated multi-stage circulating vertical partition biological denitrification reactor) for multi-stage circulating vertical partition biological denitrification. The denitrification system is divided into a 4-stage denitrification system. The mud and water after denitrification are returned to the existing MBR tank for mud-water separation, and an external carbon source is added to the first denitrification unit. The denitrification unit removes the nitrogen in the leachate, and the leachate after denitrification is lifted to the MBR tank for subsequent treatment.

[0053] Embodiment 2:

[0054] On the basis of Embodiment 1, a sludge return system is added to the denitrification system in this embodiment. The sludge return system is used to transport the sludge during the denitrification process to the front end of the first denitrification reaction unit.

[0055] The sludge return system continuously transports the sludge during the denitrification process to the front end of the first denitrification reaction unit, and participates in the leachate treatment process again. In this way, the lost sludge is continuously supplemented, the influent load is reduced, and the impact resistance of the reaction tank of the denitrification system is maximized. There is no need to set an adjustment tank at the front end of the first denitrification reaction unit. In addition, a certain flow rate can be maintained through reflux, so that the sludge layer is in a suspended state, and the ultimate impact load is strong in a short time. The denitrification system operates at a high sludge concentration, and the mixed liquid reflux ratio is large, so that each unit has some advantages of plug flow type and complete mixing type, and the concentration gradient of pollutants in the whole process is small. Especially the anoxic zone operates at a low load, and the microorganisms in the activated sludge are in the endogenous respiration period, without sludge bulking phenomenon, and the sludge production is low, saving investment and operating costs, and greatly reducing the workload of operation and management.

[0056] The nitrogen removal system of the present invention adopts a vertical flow maze structure, which makes the anaerobic and anoxic zones in the nitrogen removal system have the longest flow path under the same effective volume, so that the leachate will not short-circuit and is in the most sufficient contact with the sludge; pulsed water inlet is adopted at the front end of the first nitrogen removal unit, so that the leachate is mixed and reacted with the newly supplemented sludge. By adopting sludge circulation, a part of the activated sludge at the end of the vertical partition of the nitrogen removal system (the end of the fourth nitrogen removal unit) flows back to the front end of the first nitrogen removal unit, and denitrification is carried out very thoroughly in a relatively long anoxic process, and the carbon source in the leachate is fully utilized. In addition, the sludge in the middle of the anoxic zone of the nitrogen removal system continuously flows back to the very front end of the maze grid, the sludge maintains fluidity along the maze grid, and due to the up-and-down folding structure of the maze, a high sludge concentration is maintained, and the microbial concentration in the maze part is 15,000 - 30,000 mg / L. This makes the organic matter in the leachate degraded thoroughly and the nitrogen removal effect excellent. At the same time, the odor control is better, no any deodorization device needs to be set, and the cost is saved.

[0057] The above-described embodiments are only two preferred solutions of the present invention, and do not impose any form of limitation on the present invention. There are other variations and modifications without exceeding the technical solutions recorded in the claims.

Claims

1. A total nitrogen removal system for leachate produced water, characterized in that, it includes: A primary treatment system for filtering out larger particles in the leachate and decomposing the organic matter in the leachate; A nitrogen removal system that performs multi-stage cyclic vertical partition multiplication biological nitrogen removal, including four nitrogen removal reaction units. All four nitrogen removal reaction units utilize nitrate and an external carbon source to complete nitrogen removal. The first nitrogen removal reaction unit achieves high-concentration nitrogen removal at the first stage through high-fold circulation; the second nitrogen removal reaction unit completes high-concentration nitrogen removal at the second stage; the third nitrogen removal reaction unit completes medium-concentration nitrogen removal at the third stage; the fourth nitrogen removal reaction unit completes low-concentration nitrogen removal at the fourth stage. The fourth nitrogen removal reaction unit controls the reflux of bacteria to the input ends of the four nitrogen removal reaction units. There is a sludge area inside each nitrogen removal reaction unit to store the sludge in the separated leachate; a part of the activated sludge at the end of the vertical partition of the nitrogen removal system flows back to the front end of the first nitrogen removal reaction unit; A nitrification liquid reflux system for achieving precise control of the nitrogen removal system; A carbon source dosing system for supplementing the carbon source to the nitrogen removal system and the organic matter removal system to ensure continuous and stable discharge of the total nitrogen in the effluent up to the standard; Discharge equipment for discharging the leachate treated by the nitrogen removal system.

2. A total nitrogen removal system for leachate produced water according to claim 1, characterized in that, the fourth nitrogen removal reaction unit is also used to synchronously remove the remaining carbon source and achieve the reflux of bacteria through gas reflux and liquid level control.

3. A total nitrogen removal system for leachate produced water according to claim 1, characterized in that, the primary treatment system includes: A leachate treatment system for preliminarily treating the leachate, separating the aged sludge, and discharging the aged sludge to the discharge equipment; An organic matter removal system for degrading the organic matter in the leachate after removing the aged sludge into inorganic matter.

4. A total nitrogen removal system for leachate produced water according to claim 3, characterized in that, the leachate treatment system includes: A regulating tank for removing larger particles in the leachate and transporting the treated leachate to the comprehensive tank; A comprehensive tank for removing the insoluble inorganic matter in the leachate transported by the regulating tank and transporting the treated leachate to the UASB reactor; A UASB reactor for removing the aged sludge in the leachate transported by the comprehensive tank, transporting the leachate after removing the aged sludge to the organic matter removal system, and transporting the aged sludge to the discharge equipment.

5. A total nitrogen removal system for leachate produced water according to claim 3 or 4, characterized in that, the organic matter removal system includes an anoxic tank connected to the primary treatment system and several aerobic tanks connected in sequence, where the first aerobic tank at the head is connected to the anoxic tank, and the last aerobic tank at the end is connected to the anoxic tank and the nitrogen removal system respectively.

6. A total nitrogen removal system for leachate produced water according to claim 1, characterized in that, the discharge equipment includes: An MBR tank for removing the remaining sludge in the leachate after nitrogen removal, realizing the separation of mud and water, discharging the remaining sludge to the sludge thickening tank, and discharging the leachate after removing the remaining sludge to the nanofiltration system; A nanofiltration system for concentrating the leachate after removing the excess sludge and separating the sewage; A sludge thickening tank for reducing the moisture content of the aged sludge and the excess sludge and decreasing the volume of the aged sludge and the excess sludge.

7. An overall nitrogen removal system for leachate water production according to claim 1 or 2, characterized in that, the nitrogen removal system further includes a sludge reflux system for transporting the sludge in the nitrogen removal process to the front end of the first nitrogen removal reaction unit.

Images