A landfill leachate advanced treatment system and process for realizing effluent ultra-low ammonia nitrogen
The landfill leachate deep treatment system, which couples multi-stage membrane separation and advanced oxidation technology, has solved the problem of excessive ammonia nitrogen emissions in landfill leachate treatment, achieving ultra-low concentration emissions and pollutant reduction, simplifying the process and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA CITY ENVIRONMENT PROTECTION ENGINEERING LIMITED COMPANY
- Filing Date
- 2026-03-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing landfill leachate treatment technologies are ineffective in treating membrane concentrate, leading to excessive ammonia nitrogen emissions. Furthermore, the return of concentrated water to the incinerator corrodes the equipment and increases pollutant emissions.
The system employs a multi-stage membrane separation technology coupled with advanced oxidation technology, including a pretreatment system, a reverse osmosis unit, an evaporation system, and a low-oxygen denitrification system. Through a breakpoint chlorination tank, an MVR evaporation system, and low-oxygen denitrification treatment, it achieves deep treatment of landfill leachate, reducing the concentration of ammonia nitrogen and other pollutants.
It achieves ultra-low concentration discharge of ammonia nitrogen in landfill leachate effluent below 2 mg/L, reduces the concentration of pollutants such as COD, BOD and TSS, avoids equipment corrosion and pollutant increase, and the system is simple and low cost.
Smart Images
Figure CN122102430A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of high-concentration organic wastewater treatment technology, specifically to a deep treatment system and process for landfill leachate that achieves ultra-low ammonia nitrogen in the effluent. Background Technology
[0002] Landfill leachate is a complex wastewater with extremely high pollutant concentrations, among which ammonia nitrogen is one of the main pollutants. High concentrations of ammonia nitrogen not only seriously harm the aquatic ecosystem but also inhibit the effectiveness of subsequent biological treatment processes. Therefore, efficient removal of ammonia nitrogen from leachate has always been a technical challenge in the environmental protection field. Most domestic leachate effluent standards are based on Table 2 of the "Pollution Control Standard for Municipal Solid Waste Landfills" (GB 16889-2008), with an ammonia nitrogen emission limit of 25 mg / L. However, with increasingly stringent environmental requirements and limited environmental capacity in some areas, even stricter ammonia nitrogen emission standards have been proposed, but no such projects have yet been implemented.
[0003] Waste incineration plant leachate typically employs a combined process of "pretreatment + biological treatment + advanced treatment." Membrane treatment, as a crucial component of advanced treatment, effectively improves permeate quality. However, it inevitably generates 20%-30% of the original leachate during operation. To address the disposal of this concentrated wastewater, many waste incineration plants have adopted a method of re-injecting it into the furnace. However, with the passage of time and the accumulation of operational experience, the drawbacks of concentrated wastewater re-injection have become increasingly apparent. From an equipment perspective, the membrane concentrate has a complex composition, rich in sulfides and chlorides. In a high-temperature flue gas environment, these substances corrode the heating surfaces of the incinerator tubes, shortening the equipment's lifespan. From an environmental perspective, concentrated wastewater re-injection leads to a significant increase in pollutant content in the flue gas. With the deepening implementation of environmental protection concepts, the limitations of concentrated wastewater re-injection are becoming increasingly prominent, and advanced treatment processes for concentrated wastewater are currently under development.
[0004] Due to the high concentration of pollutants in leachate, especially ammonia nitrogen, it is difficult to achieve low-concentration emissions that meet current emission standards through efficient treatment methods. Therefore, there is an urgent need to develop a highly efficient, economical, and adaptable leachate deep treatment process to achieve ultra-low concentration emissions of ammonia nitrogen from leachate. Summary of the Invention
[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a deep treatment system and process for landfill leachate that achieves ultra-low ammonia nitrogen in the effluent, thereby solving the technical problem that the membrane concentrate obtained from landfill leachate treatment is difficult to treat and discharge in the prior art.
[0006] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a deep treatment system for landfill leachate that achieves ultra-low ammonia nitrogen in the effluent, comprising a pretreatment system, a reverse osmosis unit, an evaporation system, and a low-oxygen denitrification system connected in sequence, wherein the reverse osmosis unit is also connected to a breakpoint chlorination tank; wherein the pretreatment system is used to pretreat the landfill leachate; the reverse osmosis unit is used to treat the concentrate from the pretreatment via reverse osmosis; the evaporation system is used to evaporate the concentrate from the reverse osmosis treatment; the low-oxygen denitrification system is used to treat the condensate from the evaporation treatment via low-oxygen denitrification to achieve compliant discharge; and the breakpoint chlorination tank is used to treat the substandard permeate from the reverse osmosis treatment via breakpoint chlorination to achieve compliant discharge.
[0007] Preferably, the pretreatment system includes a pretreatment unit, an anaerobic treatment unit, an MBR system, a nanofiltration unit, and a reverse osmosis unit connected in sequence.
[0008] Preferably, the reverse osmosis unit includes a butterfly reverse osmosis unit.
[0009] Preferably, a concentrate tank is provided between the reverse osmosis unit and the evaporation system. The concentrate tank is used to receive and temporarily store the concentrate from the reverse osmosis unit.
[0010] Preferably, the evaporation system includes an MVR evaporation system.
[0011] Preferably, the hypoxia denitrification system includes an aerobic treatment unit and an anoxic treatment unit connected together.
[0012] Secondly, the present invention provides a deep treatment process for landfill leachate to achieve ultra-low ammonia nitrogen in the effluent, comprising the following steps: pretreatment of landfill leachate; reverse osmosis treatment of the concentrated water from the pretreatment; evaporation treatment of the concentrated water from the reverse osmosis treatment; breakpoint chlorination treatment of the substandard permeate from the reverse osmosis treatment to achieve standard discharge; and low-oxygen denitrification treatment of the condensate from the evaporation treatment to achieve standard discharge.
[0013] Preferably, the evaporation temperature is 40–100°C.
[0014] Preferably, the breakpoint chlorination treatment involves adding sodium hypochlorite solution to the substandard wastewater, with the amount of sodium hypochlorite added being 6 to 15 times the mass of ammonia nitrogen in the substandard wastewater.
[0015] Preferred conditions for low-oxygen denitrification treatment include: pH value of 6.5–8.0, temperature of 20–30°C, and reaction time of 6–8.5 h.
[0016] Compared with the prior art, the beneficial effects of the present invention include: This invention employs a multi-stage membrane separation technology coupled with advanced oxidation technology for deep treatment of landfill leachate. Specifically, by incorporating a breakpoint chlorination tank, it ensures that ammonia nitrogen in the reverse osmosis permeate meets discharge standards. The concentrated wastewater from the reverse osmosis treatment is further treated using an evaporation system and a low-oxygen denitrification system, achieving an effluent standard with ammonia nitrogen levels below 2 mg / L. Simultaneously, the coordinated operation of the reverse osmosis unit, evaporation system, low-oxygen denitrification system, and breakpoint chlorination tank effectively reduces the concentrations of other pollutants such as COD, BOD, and TSS in the landfill leachate. This invention achieves ultra-low concentration emissions of ammonia nitrogen from landfill leachate concentrate, and the system is simple, the process is concise, the cost is low, and it has a wide range of applications. Attached Figure Description
[0017] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0019] To address the shortcomings of current landfill leachate treatment methods that make it difficult to treat and discharge the membrane concentrate, this invention provides a landfill leachate deep treatment system and process that achieves ultra-low ammonia nitrogen in the effluent, and can stably achieve a final effluent ammonia nitrogen level of less than 2 mg / L.
[0020] In a first aspect, the present invention provides a landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in the effluent, comprising a pretreatment system, a reverse osmosis unit, an evaporation system, and a low-oxygen denitrification system connected in sequence, wherein the reverse osmosis unit is further connected to a breakpoint chlorination tank; wherein... The pretreatment system is used to pretreat landfill leachate; Reverse osmosis units are used to treat the concentrate from the pretreatment process using reverse osmosis. The evaporation system is used to evaporate the concentrate from the reverse osmosis process; The low-oxygen denitrification system is used to treat the condensate from evaporation treatment with low oxygen and nitrogen before it is discharged in compliance with standards. Breakpoint chlorination tanks are used to treat substandard permeate from reverse osmosis treatment by breakingpoint chlorination until it meets discharge standards.
[0021] In some embodiments, the pretreatment system includes a pretreatment unit, an anaerobic treatment unit, an MBR system, a nanofiltration (NF) device, and a reverse osmosis (RO) device connected in sequence; the pretreatment unit is mainly a primary sedimentation tank, on which a screen is installed. It should be noted that the pretreatment system of this invention is a conventional landfill leachate pretreatment system, which will not be described in detail here.
[0022] In some embodiments, the reverse osmosis unit includes a butterfly reverse osmosis (DTRO) unit. Specifically, the DTRO receives the concentrate from the pretreatment system (NF) and the RO unit, and further performs membrane separation. In this invention, the breakpoint chlorination tank is connected to the permeate outlet of the reverse osmosis (DTRO) unit. When the ammonia nitrogen in the permeate from the DTRO unit does not meet the standards, the ammonia nitrogen is further treated by the breakpoint chlorination tank. When the ammonia nitrogen produced by the DTRO unit meets the standards, the effluent can directly bypass the breakpoint chlorination tank, and the effluent is discharged in compliance with the standards.
[0023] In some embodiments, a concentrate tank is provided between the reverse osmosis unit and the evaporation system to receive and temporarily store the concentrate from the reverse osmosis unit.
[0024] In some embodiments, the evaporation system includes an MVR evaporation system. The MVR evaporation system is connected to a concentrate tank and separates pollutants from the concentrate in crystalline form through evaporation and crystallization. While the evaporation system can precipitate most pollutants from the concentrate in crystalline form, significantly reducing the concentration of pollutants in the condensate, the ammonia nitrogen and COD levels in the condensate still do not meet the ultra-strict emission standards. This invention incorporates a low-oxygen denitrification system to treat the condensate generated during the MVR evaporation process. Through anoxic-anaerobic biological treatment, the ammonia nitrogen concentration in the condensate can be further reduced to ultra-low levels, achieving ultra-high emission standards. The sludge from the low-oxygen denitrification system is piped to a pretreatment system and, together with the sludge generated from the pretreatment system, enters a sludge treatment system for centralized treatment.
[0025] In some embodiments, the hypoxic denitrification system includes connected aerobic and anoxic treatment units. This invention connects the influent of the hypoxic denitrification system to the condensate of the MVR evaporation system, further removing COD and ammonia nitrogen from the condensate, thereby reducing the ammonia nitrogen concentration in the effluent and achieving ultra-low concentration discharge compliance. Since the MVR evaporation system has already removed most of the COD, ammonia nitrogen, and other pollutants, but the pollutant concentration still exceeds the discharge standards, considering that the pollutant concentration in the condensate is relatively low compared to other wastewater, only a hypoxic denitrification system is needed to meet the effluent standards. The hypoxic denitrification system consists of anoxic / aerobic treatment units. In the anoxic zone, denitrifying bacteria reduce nitrates produced in the aerobic zone to nitrogen gas, achieving denitrification. In the aerobic zone, nitrifying bacteria convert ammonia nitrogen into nitrates under dissolved oxygen conditions and degrade BOD and COD.
[0026] Secondly, the present invention provides a deep treatment process for landfill leachate to achieve ultra-low ammonia nitrogen in the effluent, comprising the following steps: Pretreatment of landfill leachate; The concentrate from the pretreatment process is then subjected to reverse osmosis treatment. The concentrate from reverse osmosis is evaporated; substandard permeate from reverse osmosis is treated with breakpoint chlorination before being discharged in compliance with standards. The condensate from the evaporation process is treated with low-oxygen denitrification before being discharged in compliance with standards.
[0027] In some embodiments, the evaporation treatment temperature is 40–100°C.
[0028] In some embodiments, breakpoint chlorination treatment involves adding sodium hypochlorite solution to substandard wastewater, with the amount of sodium hypochlorite (based on available chlorine) added being 6 to 15 times the mass of ammonia nitrogen in the substandard wastewater.
[0029] In some embodiments, the conditions for low-oxygen denitrification treatment include: a pH value of 6.5–8.0, a temperature of 20–30°C, and a reaction time of 6–8.5 h. Compared with traditional denitrification processes, the low-oxygen denitrification system of the present invention requires less oxygen due to the relatively low concentration of pollutants in the influent.
[0030] The main advantages of this invention are: (1) By coupling multi-stage membrane separation technology with advanced oxidation technology, the ammonia nitrogen discharge of the effluent meets the standards with dual guarantees: A. The ammonia nitrogen in the product water meets the standards through the breakpoint chlorination tank; B. The ammonia nitrogen concentration reaches the effluent standard of less than 2 mg / L through the evaporation system + low oxygen denitrification system (the ammonia nitrogen concentration of the effluent from the conventional evaporation system is about 5 to 10 mg / L). Therefore, this invention breaks the ammonia nitrogen discharge limit of concentrated water in the traditional landfill leachate treatment technology.
[0031] (2) Other pollutant indicators are reduced simultaneously: Through DTRO, MVR evaporation system, low oxygen denitrification system and breakpoint chlorination tank, the concentration of pollutants such as COD, BOD and TSS in wastewater is reduced simultaneously, so that they all meet the stricter effluent standards.
[0032] The present invention will be further described in detail below through specific embodiments. The landfill leachate was designed with parameters of influent COD≈10000mg / L, BOD≈1000mg / L, NH4-N≈3300mg / L, TSS≈1500mg / L, and the final effluent test indicators were COD≤80mg / L, BOD≤4mg / L, NH4-N≤2mg / L, and TSS≤11mg / L.
[0033] Example 1 A deep treatment process for landfill leachate that achieves ultra-low ammonia nitrogen in the effluent, such as Figure 1 As shown, it includes the following steps: (1) Landfill leachate enters the pretreatment system for conventional pretreatment, which includes "bar + primary sedimentation tank + anaerobic treatment unit + MBR system + nanofiltration (NF) + and reverse osmosis (RO)". The pretreatment process removes most of the pollutants in the landfill leachate. The influent and effluent parameters are shown in Table 1 below: Table 1. Influent and Effluent Parameters for Landfill Leachate Pretreatment
[0034] (2) The concentration of pollutants in the concentrate from nanofiltration and reverse osmosis in the pretreatment system is too high and cannot meet the discharge standards. It needs to be further treated by advanced treatment processes. The concentrate from nanofiltration and reverse osmosis in the pretreatment system is treated by reverse osmosis using a butterfly reverse osmosis (DTRO) system. The influent and effluent parameters are shown in Table 2 below: Table 2. Inlet and outlet water parameters for reverse osmosis treatment
[0035] (3) Evaporation treatment of the concentrate from reverse osmosis: The inlet water of the MVR evaporation system is connected to the concentrate pipe of the DTRO unit. The pollutants in the DTRO concentrate are precipitated out in the form of crystals through the evaporation process. The evaporation temperature range is 80℃, thereby reducing pollutants such as COD, BOD, and ammonia nitrogen in the wastewater. However, the COD and ammonia nitrogen in the effluent still cannot meet the ultra-strict discharge standards. The condensate needs to be connected to the low-oxygen denitrification system for further treatment. The resulting concentrate can be landfilled. The specific inlet and outlet water parameters for evaporation treatment are shown in Table 3 below: Table 3. Evaporation Treatment Inlet and Outlet Water Parameters
[0036] Substandard permeate from reverse osmosis (RO) treatment is treated with breakpoint chlorination before being discharged in compliance with standards: Permeate from the DTRO unit is received via a breakpoint chlorination tank. When ammonia nitrogen levels in the DTRO permeate are below standard, the ammonia nitrogen is further treated in the breakpoint chlorination tank. When the ammonia nitrogen levels in the DTRO permeate meet standards, the effluent can bypass the breakpoint chlorination tank directly, and the effluent is discharged in compliance with standards. Sodium hypochlorite solution is added to the breakpoint chlorination tank to oxidize ammonia nitrogen into nitrate nitrogen. The dosage of sodium hypochlorite (based on available chlorine) is approximately nine times the amount of ammonia nitrogen in the permeate. The influent and effluent parameters after breakpoint chlorination treatment are shown in Table 4 below. Table 4. Breakpoint Chlorination Inlet and Outlet Water Parameters
[0037] (4) The condensate from the evaporation treatment undergoes low-oxygen denitrification treatment to meet discharge standards. Specific conditions include: pH maintained at around 7, temperature at around 20℃, and reaction time of 8.5 hours. The sludge from the low-oxygen denitrification system is discharged through a pipeline and can be further treated together with the biochemical sludge from the pretreatment system via a sludge dewatering system. The influent and effluent parameters of the evaporation treatment are shown in Table 5 below: Table 5 Influent and Effluent Parameters for Low-Oxygen Denitrification Treatment
[0038] Comparative Example 1 Compared to Example 1, the chlorination treatment at the inflection point was removed, while the other steps and conditions were the same as in Example 1.
[0039] As shown in Table 2, removing the inflection point and adding chlorine to the DTRO permeate water poses a risk of exceeding the ammonia nitrogen concentration standard.
[0040] Similarly, as shown in Table 5, if the low-oxygen denitrification treatment is removed, the ammonia nitrogen in the effluent from the evaporation treatment exceeds the standard and cannot be directly discharged.
[0041] Unlike existing technologies, this invention couples multi-stage membrane separation technology with advanced oxidation technology to deeply treat landfill leachate, especially the concentrated water obtained after pretreatment. By incorporating a breakpoint chlorination tank, it ensures that the ammonia nitrogen in the reverse osmosis permeate meets discharge standards. The concentrated water from the reverse osmosis treatment is further treated through an evaporation system and a low-oxygen denitrification system, achieving an effluent standard with ammonia nitrogen levels below 2 mg / L, thus ensuring compliant discharge. Simultaneously, the coordinated operation of the reverse osmosis unit, evaporation system, low-oxygen denitrification system, and breakpoint chlorination tank reduces the concentrations of other pollutants such as COD, BOD, and TSS in the landfill leachate. This invention achieves ultra-low concentration emissions of ammonia nitrogen from landfill leachate concentrate, and the system is simple, the process is concise, the cost is low, and the application range is wide.
[0042] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A deep treatment system for landfill leachate that achieves ultra-low ammonia nitrogen in the effluent, characterized in that, It includes a pretreatment system, a reverse osmosis unit, an evaporation system, and a low-oxygen denitrification system connected in sequence. The reverse osmosis unit is also connected to a breakpoint chlorination tank; among which, The pretreatment system is used for pretreatment of landfill leachate; The reverse osmosis device is used to treat the concentrated water from the pretreatment process using reverse osmosis. The evaporation system is used to evaporate the concentrate from the reverse osmosis treatment. The low-oxygen denitrification system is used to treat the condensate from the evaporation process with low-oxygen denitrification before it is discharged in compliance with standards. The breakpoint chlorination tank is used to treat substandard permeate water from reverse osmosis treatment with breakpoint chlorination until it meets discharge standards.
2. The landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in effluent according to claim 1, characterized in that, The pretreatment system includes a pretreatment unit, an anaerobic treatment unit, an MBR system, a nanofiltration unit, and a reverse osmosis unit connected in sequence.
3. The landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in effluent according to claim 1, characterized in that, The reverse osmosis device includes a butterfly reverse osmosis device.
4. The landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in effluent according to claim 1, characterized in that, A concentrate tank is provided between the reverse osmosis unit and the evaporation system. The concentrate tank is used to receive and temporarily store the concentrate from the reverse osmosis unit.
5. The landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in effluent according to claim 1, characterized in that, The evaporation system includes an MVR evaporation system.
6. The landfill leachate deep treatment system for achieving ultra-low ammonia nitrogen in effluent according to claim 1, characterized in that, The hypoxia denitrification system includes an aerobic treatment unit and an anoxic treatment unit connected together.
7. A deep treatment process for landfill leachate achieving ultra-low ammonia nitrogen in effluent using the system described in any one of claims 1-6, characterized in that, Includes the following steps: Pretreatment of landfill leachate; The concentrate from the pretreatment process is then subjected to reverse osmosis treatment. The concentrate from the reverse osmosis treatment is evaporated; the substandard permeate from the reverse osmosis treatment is treated with breakpoint chlorination before being discharged in compliance with standards. The condensate from the evaporation process is treated with low-oxygen denitrification before being discharged in compliance with standards.
8. The deep treatment process for landfill leachate to achieve ultra-low ammonia nitrogen in effluent according to claim 7, characterized in that, The evaporation process is carried out at a temperature of 40–100°C.
9. The deep treatment process for landfill leachate to achieve ultra-low ammonia nitrogen in effluent according to claim 7, characterized in that, The breakpoint chlorination treatment involves adding sodium hypochlorite solution to substandard wastewater, with the sodium hypochlorite dosage being 6 to 15 times the mass of ammonia nitrogen in the substandard wastewater.
10. The deep treatment process for landfill leachate to achieve ultra-low ammonia nitrogen in effluent according to claim 7, characterized in that, The conditions for the low-oxygen denitrification treatment include: pH value of 6.5-8.0, temperature of 20-30℃, and reaction time of 6-8.5h.