A tower-type denitrification reaction equipment and process for landfill leachate

Abstract

The present invention provides a tower-type denitrification reaction device and process for landfill leachate, comprising a UASB reactor, a nitrification tank, a material mixer, and a denitrification tower. The UASB reactor is provided with a gas-liquid separation device to separate materials generated by landfill leachate in the reactor into waste gas and waste liquid. The waste liquid is input into the nitrification tank, which is provided with an ammonia nitrogen detector and a nitric nitrogen and total nitrogen detector. The nitrification tank is linked with an aeration device of the nitrification tank through a PLC control program to achieve intelligent control of the air intake of the aeration device, thereby saving fan energy consumption and reducing labor waste. The waste liquid discharged from the nitrification tank and the waste gas discharged from the UASB reactor are mixed in the material mixer and then discharged into the denitrification tower. The waste gas plays a stirring role in the denitrification reaction, effectively increasing the denitrification reaction rate. The denitrification tower is provided with a nitrate nitrogen separation device to separate residual nitrate nitrogen. The separated nitrate nitrogen is refluxed to the UASB reactor to react with the landfill leachate, thereby achieving full utilization of the carbon source.

Description

Technical Field

[0001] The present invention relates to the field of landfill leachate treatment, and in particular to a landfill leachate tower-type denitrification reaction device and a treatment process. Background Art

[0002] The statements herein merely provide background information related to the present disclosure and may not necessarily constitute prior art.

[0003] Eutrophication has been a global phenomenon for decades. Although biochemical treatment in urban wastewater treatment plants can eliminate most pollutants, the effluent concentration of total nitrogen remains high. Traditional single processes can no longer meet the country's growing demand for total nitrogen and carbon emission reduction goals.

[0004] To improve the water quality of receiving water bodies, nitrogen in the secondary effluent of sewage treatment processes urgently needs to be deeply treated, especially for the treatment of landfill leachate. Because landfill leachate has a high total nitrogen value, conventional denitrification processes require a large amount of carbon source and external carbon source supplementation, which indirectly leads to the production of large amounts of sludge and increases solid waste treatment costs. For example, Chinese utility model patent - CN203976580U discloses a landfill leachate treatment device that removes ammonia nitrogen from landfill leachate through nitrification and organic matter and nitrate nitrogen from landfill leachate through denitrification. However, this device has the following problems: when the denitrification technology based on heterotrophic denitrification is applied to landfill leachate with high total nitrogen influent, ammonia poisoning caused by the high total nitrogen content can occur, making it difficult to meet discharge indicators. In addition, the low level of automation in landfill leachate treatment also leads to excessive manual labor and incorrect operations, which further increases the cost of denitrification treatment. Summary of the Invention

[0005] In order to address the deficiencies of the prior art, the present invention aims to provide a tower-type denitrification reaction equipment and process for landfill leachate, thereby improving the utilization rate of elements in landfill leachate, reducing the amount of solid waste generated in the treatment process, and enhancing the efficiency of landfill leachate treatment.

[0006] In order to achieve the above object, the technical solution of the present invention is:

[0007] In a first aspect, a tower-type denitrification reaction equipment for landfill leachate includes a UASB reactor, a nitrification tank, a material mixer, and a denitrification tower;

[0008] The UASB reactor is provided with a landfill leachate inlet, a reflux material inlet is provided at the bottom of the UASB reactor, and a gas-liquid separation device is provided at the top of the UASB reactor; a liquid material outlet is provided in the middle of the gas-liquid separation device, and a gas material outlet is provided at the top of the gas-liquid separation device; a waste liquid inlet and a waste liquid outlet are provided at the top of the nitrification tank; a mixed material inlet is provided at the bottom of the denitrification tower, a nitrate nitrogen outlet is provided at the top of the denitrification tower, and the denitrification tower is provided with a landfill leachate outlet; the material mixer is provided with a waste liquid inlet and an exhaust gas inlet, and the material mixer is provided with a mixed material outlet;

[0009] The reflux material inlet of the UASB reactor is connected to the nitrate nitrogen outlet of the denitrification tower; the liquid phase material outlet of the gas-liquid separation device is connected to the waste liquid inlet of the nitrification tank, and the gas phase material outlet of the gas-liquid separation device is connected to the waste gas inlet of the material mixer; the waste liquid outlet of the nitrification tank is connected to the waste liquid inlet of the material mixer; the mixed material outlet of the material mixer is connected to the mixed material inlet of the denitrification tower; and the nitrate nitrogen outlet of the denitrification tower is connected to the reflux material inlet of the UASB reactor.

[0010] First, the present invention sets a gas-liquid separation device on the top of the UASB reactor to separate the materials generated by the landfill leachate in the reactor into gaseous and liquid phase materials. The separated liquid phase material enters the nitrification tank for ammonia nitrogen nitrification reaction, while the separated gas phase material passes through the nitrification tank and is connected to the material mixer. By separating the waste gas, it is possible to avoid the competition of waste gas oxidation for dissolved oxygen in the nitrification tank, thereby reducing the energy consumption of the fan of the aeration device and achieving the effect of energy conservation. In addition, the sulfide contained in the landfill leachate enters the gas phase from the liquid phase, which not only avoids the sulfide from competing for dissolved oxygen in the nitrification tank, but also prevents the toxicity of the sulfide from inhibiting the nitrification reaction, effectively improving the overall treatment efficiency of the landfill leachate. The separated waste gas finally enters the bottom of the denitrification tower, which can play a sufficient stirring role to increase the denitrification efficiency of the wastewater. The carbon dioxide contained in the waste gas dissolves in water and converts into carbonate, which can replenish a certain amount of alkalinity and play a buffering role. The sulfide contained in the waste gas can serve as a denitrification substrate, further improving the overall denitrification efficiency of the device.

[0011] The nitrate nitrogen product generated by the denitrification tower is refluxed to the UASB reactor, so that the nitrate nitrogen contacts and reacts with the landfill leachate, and the carbon source in the landfill leachate is utilized to achieve the effect of reducing total nitrogen. Compared with the conventional denitrification process which requires additional carbon source supplementation, the present invention effectively utilizes the elements contained in the landfill leachate, which not only reduces the amount of sludge solid waste, but also improves the utilization rate of sewage elements.

[0012] On the other hand, a landfill leachate denitrification process is provided. After decarbonization and desulfurization in a UASB reactor, the landfill leachate generates ammonia nitrogen-containing waste liquid and carbon and sulfur-containing waste gas. The waste liquid flows into a nitrification tank for nitrification reaction. The nitrification reaction oxidizes the ammonia nitrogen in the water into nitrite nitrogen or nitric nitrogen. The waste liquid flowing out of the nitrification tank and the waste gas separated in the UASB reactor are mixed in a material mixer and passed into the bottom of a denitrification tower. The waste liquid is denitrified in the denitrification tower, and the waste gas plays a role in stirring the waste liquid and accelerating the reaction efficiency of the waste liquid. The nitrate nitrogen generated in the denitrification tower is refluxed to the UASB reactor and reacts with the carbon source in the landfill leachate to reduce the total nitrogen content in the waste liquid, thereby overcoming the disadvantage of traditional aerobic denitrification with a large amount of solid waste.

[0013] The beneficial effects of the present invention are:

[0014] The present invention separates and discharges ammonia nitrogen-containing waste liquid from carbon and sulfur-containing waste gas, thereby preventing sulfur element in the waste gas from participating in the nitrification tank reaction and improving the generation efficiency of nitrite nitrogen and nitric nitrogen. The waste gas not only provides a substrate for a denitrification tower and adjusts the reaction conditions of the denitrification tower, but also plays a stirring role, thereby improving the overall reaction efficiency, achieving the purpose of combining the processes, fully utilizing the carbon and sulfur resources in the original waste liquid, and improving the sewage treatment efficiency. Moreover, through the pre-reflux of nitrate nitrogen, the rich carbon source in the landfill leachate is fully utilized, and the nitrogen element can be efficiently removed without adding an additional carbon source, thereby meeting the total nitrogen discharge standard and improving the water environment quality of the receiving water body. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0016] Figure 1 This is a schematic structural diagram of a tower-type denitrification reaction equipment for landfill leachate according to Example 1 of the present invention;

[0017] Among them, 1-UASB reactor, 2-gas-liquid separation device, 3-ammonia nitrogen detector, 4-nitrogen and total nitrogen detector, 5-nitrification tank, 6-aeration device, 7-denitrification tower, 8-filling carrier, 9-nitrate nitrogen separation device, 10-gas distribution pipe, 11-material mixer, 12-reflux pipe, 13-flow meter. DETAILED DESCRIPTION

[0018] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0019] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0020] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0021] Example 1

[0022] In order to improve the utilization rate of elements in landfill leachate, reduce the amount of solid waste generated in the treatment process, and enhance the treatment efficiency of landfill leachate, the present invention proposes a landfill leachate tower denitrification reaction equipment and process.

[0023] A typical embodiment of the present invention provides a tower-type denitrification reaction equipment for landfill leachate, comprising a UASB reactor 1, a nitrification tank 5, a material mixer 11, and a denitrification tower 7;

[0024] The UASB reactor 1 is provided with a wastewater inlet, a reflux material inlet is provided at the bottom of the UASB reactor 1, and a gas-liquid separation device 2 is provided at the top of the UASB reactor 1; a liquid material outlet is provided in the middle of the gas-liquid separation device 2, and a gas material outlet is provided at the top of the gas-liquid separation device 2; a waste liquid inlet and a waste liquid outlet are provided at the top of the nitrification tank 5; a mixed material inlet is provided at the bottom of the denitrification tower 7, a nitrate nitrogen outlet is provided at the top of the denitrification tower 7, and a landfill leachate outlet is provided at the denitrification tower 7; the material mixer 11 is provided with a waste liquid inlet and an exhaust gas inlet, and the material mixer 11 is provided with a mixed material outlet;

[0025] The reflux material inlet of the UASB reactor 1 is connected to the nitrate nitrogen outlet of the denitrification tower 7; the liquid phase material outlet of the gas-liquid separation device 2 is connected to the waste liquid inlet of the nitrification tank 5, and the gas phase material outlet of the gas-liquid separation device 2 is connected to the waste gas inlet of the material mixer 11; the waste liquid outlet of the nitrification tank 5 is connected to the waste liquid inlet of the material mixer 11; the mixed material outlet of the material mixer 11 is connected to the mixed material inlet of the denitrification tower 7; and the nitrate nitrogen outlet of the denitrification tower 7 is connected to the reflux material inlet of the UASB reactor 1;

[0026] Specifically, in this embodiment, a gas-liquid separation device 2 is provided on top of the UASB reactor 1. The separated liquid-phase material enters the nitrification tank 5 for ammonia nitrogen nitrification reaction, while the separated gas-phase material passes through the nitrification tank 5 and is connected to the material mixer 11. By separating the waste gas, it is possible to prevent the oxidation of the waste gas from competing with the dissolved oxygen in the nitrification tank 5, thereby reducing the fan energy consumption of the aeration device 6 and achieving the effect of energy conservation. In addition, the sulfide contained in the landfill leachate enters the gas phase from the liquid phase. In addition to preventing the sulfide from competing with the dissolved oxygen in the nitrification tank 5, it also prevents the toxicity of the sulfide from inhibiting the nitrification reaction, effectively improving the overall landfill leachate treatment efficiency.

[0027] The nitrification tank 5 described in this embodiment is provided with an ammonia nitrogen detector 3 and a nitric nitrogen and total nitrogen detector 4, and an aeration device 6 is also installed at the bottom of the nitrification tank 5; the ammonia nitrogen detector 3 and the nitric nitrogen and total nitrogen detector 4 are linked with the aeration device 6 at the bottom of the nitrification tank 5 through a PLC control program to realize automatic control of the nitrification rate, thereby solving the problem of conventional devices lacking automated design and being prone to incorrect manual operation, thereby reducing the cost of additional denitrification treatment.

[0028] In this embodiment, an air distribution system 10 is provided at the bottom of the denitrification tower 7; the denitrification tower 7 is also provided with a filler carrier 8, and the filler carrier 8 carries denitrification bacteria, so that the waste liquid is denitrified when the waste liquid passes through the carrier; the air distribution system 10 is connected to the mixed material inlet of the denitrification tower 7, and the waste liquid and the waste gas are filled into the denitrification tower 7 together, and the waste liquid and the waste gas pass through the filler carrier 8; the carrier contains domesticated low-carbon denitrification autotrophic bacteria, and under the influence of the denitrification bacteria in the carrier, the nitrogen in the waste liquid is gradually fixed, and the waste gas can play a sufficient stirring role to increase the number of contacts between the carrier, microorganisms and wastewater, thereby effectively improving the reaction rate; and because the waste gas contains carbon and sulfur elements, it can play a role in regulating alkalinity and supplementing substrates, further improving the reaction efficiency.

[0029] The denitrification tower 7 of this embodiment is provided with a nitrate nitrogen separation device 9 at the top of the tower. After denitrification is completed, the residual nitrate nitrogen is separated by the tower top separation device, and the separated nitrate nitrogen is refluxed to the UASB reactor 1. The UASB reactor 1 is filled with landfill leachate rich in carbon elements, and the nitrate nitrogen reacts with the landfill leachate to achieve the effect of reducing total nitrogen. Compared with the conventional denitrification process that requires additional carbon source, the present invention effectively utilizes the elements contained in the landfill leachate, which not only reduces the amount of sludge solid waste, but also improves the utilization rate of elements in sewage.

[0030] Furthermore, the nitrate nitrogen enters the UASB reactor through a reflux pipe 12. A flow meter 13 is provided on the reflux pipe 12. The flow meter 13 is used to monitor the nitrate nitrogen flow rate to ensure a stable mixing ratio of nitrate nitrogen and landfill leachate, so that the landfill leachate can provide sufficient carbon elements to ensure sufficient reaction of the reflux nitrate nitrogen and effectively reduce the nitrogen content of the waste liquid.

[0031] Example 2

[0032] Another embodiment of the present invention provides a landfill leachate denitrification process. After decarbonization and desulfurization in a UASB reactor 1, the landfill leachate generates ammonia nitrogen-containing waste liquid and carbon and sulfur-containing waste gas. The waste liquid flows into a nitrification tank 5 for a nitrification reaction. The nitrification reaction oxidizes the ammonia nitrogen in the water into nitrite nitrogen or nitric nitrogen. The waste liquid flowing out of the nitrification tank 5 and the waste gas separated in the UASB reactor 1 are mixed in a material mixer 11 and passed into the bottom of a denitrification tower 7. The waste liquid is denitrified in the denitrification tower 7, and the waste gas serves to agitate the waste liquid and accelerate the reaction efficiency of the waste liquid. The nitrate nitrogen generated in the denitrification tower 7 is refluxed to the UASB reactor 1 and reacts with the carbon source in the landfill leachate to reduce the total nitrogen content in the waste liquid, thereby overcoming the disadvantage of traditional aerobic denitrification with a large amount of solid waste.

[0033] Specifically, the nitrification tank 5 described in this embodiment is provided with an ammonia nitrogen detector 3 and a nitric nitrogen and total nitrogen detector 4, and is linked to the aeration device 6 at the bottom of the nitrification tank 5 through a PLC control program; when the ammonia nitrogen value exceeds the upper limit, the ammonia nitrogen detector 3 feedbacks a signal, and the PLC module controls the aeration device 6 to increase the air volume; when the ammonia nitrogen value is lower than the lower limit, and the difference between the total nitrogen and nitric nitrogen values ​​is less than the limit value, the PLC module controls the aeration device 6 to reduce the air volume, in order to control the ammonia nitrogen nitrification rate, and at the same time control part of the ammonia nitrogen nitrification in the nitrite stage to reduce the fan energy consumption of the aeration device 6.

[0034] In one or more examples of this embodiment, the upper limit of the ammonia nitrogen value is 10 mg / L.

[0035] In one or more examples of this embodiment, the lower limit of the ammonia nitrogen value is 5 mg / L, and the limit value of the difference between the total nitrogen and nitrate nitrogen values ​​is 20 mg / L.

[0036] In one or more examples of this embodiment, the ammonia nitrogen nitrification rate is controlled at 98%.

[0037] In one or more examples of this embodiment, the nitrite-nitrogen content of ammonia is controlled at 30-70%.

[0038] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0039] The implementation steps of a landfill leachate denitrification process are as follows:

[0040] 1) Landfill leachate wastewater was added to a UASB reactor 1. The leachate contained 820 mg / L ammonia nitrogen, 1400 mg / L organic nitrogen, approximately 2220 mg / L total nitrogen, and approximately 12,000 mg / L chemical oxygen demand. After the reaction was completed, the preliminarily treated landfill leachate was separated into waste liquid, which was input to a nitrification tank 5, and waste gas, which was input to a material mixer 11, via a gas-liquid separator 2.

[0041] 2) The air intake of the aeration device 6 is controlled by the ammonia nitrogen detector 3 and the nitrate nitrogen and total nitrogen detector 4. When the ammonia nitrogen value exceeds 10 mg / L, the feedback signal increases the air intake; when the ammonia nitrogen value is less than 5 mg / L and the difference between the total nitrogen and nitrate nitrogen values ​​is less than 20 mg / L, the air intake is reduced to achieve a nitrification rate of more than 98% for ammonia nitrogen, and at the same time control the proportion of nitrite nitrogen in the nitrification tank 5 to 30-70% and nitrate nitrogen to 20-40%.

[0042] 3) The waste liquid discharged from the nitrification tank 5 and the waste gas discharged from the UASB reactor 1 are mixed in a material mixer 11. After mixing, the mixed gas is discharged into the denitrification tower 7 through a gas distribution system 10 connected to the material mixer 11. The gas distribution system 10 is 50 cm thick. The gas distribution system 10 discharges the liquid and gas materials into a packing carrier 8 for denitrification. The packing carrier 8 is 2 m thick.

[0043] 4) After the waste liquid is denitrified, the nitrate nitrogen in the waste liquid is extracted by the nitrate nitrogen separation device 9 and the nitrate nitrogen is refluxed to the UASB reactor 1. During operation, the water inlet volume and the nitrate nitrogen reflux volume of the UASB reactor 1 are controlled to be maintained at 1: (2-6).

[0044] After treatment with the landfill leachate denitrification process described in this embodiment, the total nitrogen content of the system effluent is less than 35 mg / L, solving the problem of excessively high total nitrogen content in treated wastewater. Furthermore, this embodiment intelligently controls the air volume of the aeration device 6, effectively controlling the fan energy consumption of the aeration device 6, thereby saving 20-45% of fan energy consumption and 20-45% of labor. Furthermore, this embodiment reflows the nitrate nitrogen generated after the reaction in the denitrification tower 7 to the UASB reactor 1, utilizing the carbon in the landfill leachate without the need for an external carbon source, thereby reducing sludge production by 30-40%.

[0045] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A tower type denitrification reaction equipment for landfill leachate, characterized in that: Including UASB reactor, nitrification tank, material mixer, denitrification tower; The UASB reactor is provided with a landfill leachate inlet and a reflux material inlet; the UASB reactor is provided with a gas-liquid separation device, and the gas-liquid separation device is provided with a liquid material outlet and a gas material outlet; the nitrification tank is provided with a waste liquid inlet and a waste liquid outlet; the denitrification tower is provided with a mixed material inlet, a nitrate nitrogen outlet, and a landfill leachate outlet; the material mixer is provided with a waste liquid inlet and a waste gas inlet, and the material mixer is provided with a mixed material outlet; The reflux material inlet of the UASB reactor is connected to the nitrate nitrogen outlet of the denitrification tower; the liquid phase material outlet of the gas-liquid separation device is connected to the waste liquid inlet of the nitrification tank, and the gas phase material outlet of the gas-liquid separation device is connected to the waste gas inlet of the material mixer; the waste liquid outlet of the nitrification tank is connected to the waste liquid inlet of the material mixer; the mixed material outlet of the material mixer is connected to the mixed material inlet of the denitrification tower; The nitrification tank is equipped with an ammonia nitrogen detector and a nitric nitrogen and total nitrogen detector, and the nitrification tank is also equipped with an aeration device; The denitrification tower is provided with an air distribution system, and the air distribution system is connected to the material mixer through the mixed material inlet of the denitrification tower.

2. The tower type denitrification reaction equipment for landfill leachate according to claim 1, characterized in that: The ammonia nitrogen detector and the nitric nitrogen and total nitrogen detectors are linked with the aeration device through a PLC control program to control the air intake of the aeration device.

3. The tower type denitrification reaction equipment for landfill leachate according to claim 1, characterized in that: The denitrification tower is further provided with a filler carrier, which carries denitrifying bacteria, and achieves denitrification of the waste liquid when the waste liquid passes through the filler carrier.

4. The tower type denitrification reaction equipment for landfill leachate according to claim 3, characterized in that: The denitrification tower is provided with a nitrate nitrogen separation device, which is connected to a nitrate nitrogen outlet; the nitrate nitrogen separation device separates residual nitrate nitrogen from the denitrified waste liquid, and the separated nitrate nitrogen is refluxed to the UASB reactor.

5. A landfill leachate denitrification process, characterized in that: After decarbonization and desulfurization in the UASB reactor, the landfill leachate generates ammonia-nitrogen waste liquid and carbon- and sulfur-containing waste gas. The waste liquid flows into the nitrification tank for nitrification reaction. The nitrification reaction oxidizes the ammonia nitrogen in the water into nitrite nitrogen or nitric nitrogen. The waste liquid flowing out of the nitrification tank and the waste gas separated in the UASB reactor are mixed in a material mixer and passed into the denitrification tower. The waste liquid is denitrified in the denitrification tower, and the waste gas stirs the waste liquid and accelerates the reaction efficiency of the waste liquid. The nitrate nitrogen generated in the denitrification tower is refluxed to the UASB reactor and reacts with the carbon source in the landfill leachate to reduce the total nitrogen content in the waste liquid.

6. A landfill leachate denitrification process as claimed in claim 5, characterized in that: The nitrification tank is equipped with an ammonia nitrogen detector and a nitric nitrogen and total nitrogen detector, and is linked to the aeration device of the nitrification tank through a PLC control program; when the ammonia nitrogen value exceeds the upper limit, the ammonia nitrogen detector feedback signal, and the PLC module controls the aeration device to increase the air volume; when the ammonia nitrogen value is lower than the lower limit, and the difference between the total nitrogen and nitric nitrogen values ​​is less than the limit value, the PLC module controls the aeration device to reduce the air volume, thereby controlling the ammonia nitrogen nitrification rate and controlling the nitrite nitrogen content in the nitrification tank to reduce the air intake energy consumption of the aeration device.

7. A landfill leachate denitrification process as claimed in claim 6, characterized in that: The upper limit of the ammonia nitrogen value is 10 mg / L.

8. The landfill leachate denitrification process according to claim 6, wherein: The lower limit of the ammonia nitrogen value is 5 mg / L, and the limit value of the difference between the total nitrogen and nitrate nitrogen values ​​is 20 mg / L.

9. The landfill leachate denitrification process according to claim 7, wherein: The nitrite nitrogen content is controlled at 30-70%.

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