Anaerobic treatment system for landfill leachate

Abstract

The utility model provides a landfill leachate anaerobic treatment system, and belongs to the technical field of landfill leachate treatment. The system comprises a pretreatment unit, an adjusting tank, an anaerobic treatment unit, a biological aerated filter, a nanofiltration membrane unit and a reverse osmosis unit which are sequentially communicated, the pretreatment unit is used for removing larger suspended matters in the landfill leachate; the anaerobic treatment unit is used for performing anaerobic treatment on the landfill leachate to decompose organic matters and generate biogas; the biological aerated filter is used for removing small molecular organic matters in the landfill leachate treated by the anaerobic treatment unit; the nanofiltration membrane unit is used for filtering the landfill leachate treated by the biological aerated filter to form concentrated water and produced water; the reverse osmosis unit is used for concentrating the concentrated water to form secondary concentrated water and produced water. The landfill leachate anaerobic treatment system is stable in mud-water separation effect, low in sludge yield, high in anti-pollution capacity, capable of reducing membrane pollution, stable in produced water flux and water quality and low in treatment cost.

Description

Technical Field

[0001] The present disclosure relates to the technical field of landfill leachate treatment, and in particular to an anaerobic treatment system for landfill leachate. Background Art

[0002] Landfill leachate is a high-concentration organic wastewater with large fluctuations in water quality and quantity. It contains a large amount of difficult-to-degrade substances such as non-chlorinated aromatic compounds such as naphthalene and phenanthrene, as well as ammonia nitrogen and some toxic substances. It is very difficult to treat, especially the heavy metal ions and organic matter it contains, which can exist in the environment for a long time, causing great and wide-ranging harm.

[0003] Common leachate treatment methods include physical treatment technologies: evaporation, coagulation and sedimentation, blowing and membrane separation; and biological treatment technologies: aerobic biological method and anaerobic biochemical method.

[0004] Anaerobic treatment technology is one of the key methods for treating landfill leachate. In anaerobic treatment units, acidogenic bacteria first convert complex macromolecules into organic acids, which are then converted by methanogenic bacteria into carbon dioxide and methane, producing a small amount of sludge. Anaerobic treatment technology offers low operating costs and expenses, minimal energy consumption, simple operation, low sludge production, and improved biodegradability, making it suitable for treating landfill leachate with poor biodegradability and high organic content.

[0005] In existing technologies, anaerobic treatment technology is limited by the separation efficiency and effectiveness of three separators, and suffers from defects such as anaerobic microbial loss and long biological stabilization time, resulting in large fluctuations in anaerobic treatment operation. To this end, traditional anaerobic treatment technology is combined with microfiltration / ultrafiltration membrane technology to form an anaerobic membrane bioreactor (AnMBR). However, due to the high concentration of anaerobic biogas slurry microorganisms and the presence of some undegraded organic matter, conventional anaerobic MBRs currently suffer from severe membrane fouling and inflexible effluent flux. Utility Model Content

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an anaerobic treatment system for landfill leachate, so as to achieve stable mud-water separation effect, reduce membrane pollution, and stabilize water production flux and water quality.

[0007] In order to achieve the above-mentioned utility model purpose, the present disclosure adopts the following technical solutions:

[0008] A landfill leachate anaerobic treatment system, comprising a pretreatment unit, a regulating tank, an anaerobic treatment unit, an aerated biological filter, a nanofiltration membrane unit, and a reverse osmosis unit connected in sequence;

[0009] The pretreatment unit is used to remove larger suspended solids in the landfill leachate;

[0010] The anaerobic treatment unit is used to perform anaerobically treatment on the landfill leachate to decompose organic matter and generate biogas;

[0011] The biological aeration filter is used to remove small molecular organic matter in the landfill leachate treated by the anaerobic treatment unit;

[0012] The nanofiltration membrane unit is used to filter the landfill leachate treated by the biological aeration filter to form concentrated water and produced water;

[0013] The reverse osmosis unit is used to concentrate the concentrated water to form secondary concentrated water and produced water.

[0014] In an exemplary embodiment of the present disclosure, the system further includes an anaerobic incineration unit, the feed port of the anaerobic incineration unit being connected to one of the discharge ports of the anaerobic treatment unit and the reverse osmosis unit, respectively, to incinerate the biogas and the secondary concentrated water.

[0015] In an exemplary embodiment of the present disclosure, the system further comprises a sludge conditioning and drying unit, wherein the feed port of the sludge conditioning and drying unit is respectively connected to one of the discharge ports of the anaerobic treatment unit and the biological aeration filter;

[0016] The sludge conditioning and drying unit is used to perform filter press treatment on the sludge discharged from the anaerobic treatment unit and the biological aeration filter to achieve mud-water separation.

[0017] In an exemplary embodiment of the present disclosure, the pretreatment unit adopts a rotary drum screen machine and a primary sedimentation tank.

[0018] In an exemplary embodiment of the present disclosure, the anaerobic treatment unit comprises:

[0019] A tank body, wherein a plurality of brackets are evenly distributed on the outer wall of the tank body, a rotating shaft is rotatably provided inside the tank body, and the bottom end of the rotating shaft extends out of the tank body and is connected to the driven wheel;

[0020] A diaphragm assembly, wherein a plurality of diaphragm assemblies are stacked together, disposed in the tank body, and sleeved on the rotating shaft;

[0021] A driving motor is provided on one side of the tank body, wherein a driving wheel is provided at the output end of the driving motor, and a belt is used to transmit the power between the driving wheel and the driven wheel;

[0022] An anaerobic treatment tank is provided on one side of the tank body, wherein the discharge port of the anaerobic treatment tank is connected to the feed port of the tank body through a feed barrel, one discharge port of the tank body is connected to the feed barrel, and an exhaust pipe is connected to the anaerobic treatment tank;

[0023] The water production barrel is arranged on one side of the tank body, and the feed port of the water production barrel is connected with another discharge port of the tank body.

[0024] In an exemplary embodiment of the present disclosure, the membrane assembly includes a mounting frame, a filter plate located in the middle of the mounting frame, drainage brackets located on both sides of the filter plate, a filter membrane located on a side of the drainage bracket away from the filter plate, and a scraper located above the filter membrane;

[0025] The cross section of the scraper is S-shaped. The rotating shaft passes through the center of the scraper and is fixedly connected to the scraper. Two through grooves are provided on the scraper, and the two through grooves are symmetrically arranged on both sides of the rotating shaft.

[0026] In an exemplary embodiment of the present disclosure, the diaphragm assembly further includes a feed hole, a first liquid outlet hole, and a second liquid outlet hole;

[0027] The feed hole is connected to the filter membrane on the upper layer;

[0028] The first liquid outlet is in communication with the filter plate;

[0029] The second liquid outlet is connected to the filter membrane;

[0030] A plurality of the feed holes are stacked to form a feed pipe, a plurality of the first liquid outlet holes are stacked to form a first discharge pipe, and a plurality of the second liquid outlet holes are stacked to form a second discharge pipe.

[0031] In an exemplary embodiment of the present disclosure, the filler of the biological aerated filter is natural zeolite, and the particle size of the natural zeolite is 3-5 mm.

[0032] In an exemplary embodiment of the present disclosure, the nanofiltration membrane unit adopts an NFDK type nanofiltration membrane.

[0033] In an exemplary embodiment of the present disclosure, the reverse osmosis unit adopts a high-pressure disc-tube reverse osmosis membrane.

[0034] Beneficial effects of the present disclosure:

[0035] (1) The utility model provides an anaerobic treatment system for landfill leachate, which adopts an upflow AnMBR to replace the traditional three-phase separator. The anaerobic treatment system has stable mud-water separation effect, high separation efficiency and low maintenance cost; the upflow AnMBR has the advantages of complete retention of biomass and pathogens, low sludge production, small footprint and good stability; the upflow AnMBR uses an amphoteric anti-pollution ion membrane to greatly reduce membrane pollution caused by adsorption and enrichment of organic matter on the membrane surface, and generates forced circulation cross-flow filtration by high-speed rotation of the scraper on the membrane surface, thereby avoiding the formation of a pollution layer to the greatest extent and destroying the formation of concentration polarization, so that the anti-pollution ability of the membrane component is greatly improved, and it is suitable for the environment with high suspended solids and high organic matter concentration of anaerobic biogas slurry.

[0036] (2) The utility model provides an anaerobic treatment system for landfill leachate, which adopts a combined device of aerated biological filter + nanofiltration + reverse osmosis, has good mud-water separation effect, strong pollutant interception ability, ensures that organic matter and salt are discharged in compliance with standards, ensures stable water flux and water quality, does not generate additional waste, and is more environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0038] Figure 1 This is a schematic structural diagram of an anaerobic treatment system for landfill leachate in one embodiment of the present disclosure;

[0039] Figure 2 This is a schematic structural diagram of an anaerobic treatment unit in one embodiment of the present disclosure;

[0040] Figure 3 This is a top view of the connection between the tank body, the anaerobic treatment tank, the feed tank, and the water production tank in one embodiment of the present disclosure;

[0041] Figure 4 This is a schematic structural diagram of a diaphragm assembly in one embodiment of the present disclosure;

[0042] Figure 5 This is a top view of a diaphragm assembly in one embodiment of the present disclosure.

[0043] Description of reference numerals:

[0044] 1. Pretreatment unit; 2. Equalization tank; 3. Anaerobic treatment unit; 4. Biological aerated filter; 5. Nanofiltration membrane unit; 6. Reverse osmosis unit; 7. Anaerobic incineration unit; 8. Sludge conditioning and drying unit; 9. Tank body; 10. Rotating shaft; 11. Driven pulley; 12. Diaphragm assembly; 13. Driving motor; 14. Driving pulley; 15. Anaerobic treatment tank; 16. Mounting frame; 17. Filter plate; 18. Drain bracket; 19. Filter membrane; 20. Scraper; 21. Feed hole; 22. First liquid outlet; 23. Second liquid outlet; 24. Exhaust pipe; 25. Bracket; 26. Feed barrel; 27. Water production barrel. DETAILED DESCRIPTION

[0045] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0046] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0047] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0048] The present disclosure provides an anaerobic treatment system for landfill leachate. Figure 1The system includes a pretreatment unit 1, a regulating tank 2, an anaerobic treatment unit 3, an aerated biological filter 4, a nanofiltration membrane unit 5 and a reverse osmosis unit 6 which are connected in sequence; the pretreatment unit 1 is used to remove larger suspended solids in the landfill leachate; the anaerobic treatment unit 3 is used to perform anaerobically treatment on the landfill leachate to decompose organic matter and produce biogas; the aerated biological filter 4 is used to remove small molecular organic matter in the landfill leachate treated by the anaerobic treatment unit 3; the nanofiltration membrane unit 5 is used to filter the landfill leachate treated by the aerated biological filter 4 to form concentrated water and produced water; the reverse osmosis unit 6 is used to concentrate the concentrated water to form secondary concentrated water and produced water.

[0049] In the embodiment of the present disclosure, the anaerobic treatment system is composed of a pretreatment unit 1, a regulating tank 2, an anaerobic treatment unit 3, an aerated biological filter 4, a nanofiltration membrane unit 5 and a reverse osmosis unit 6 connected in sequence. The anaerobic treatment unit 3 is an upflow AnMBR. The landfill leachate flows through the pretreatment unit 1, the regulating tank 2, the anaerobic treatment unit 3, the aerated biological filter 4, the nanofiltration membrane unit 5 and the reverse osmosis unit 6 in sequence. The large suspended solids in the landfill leachate are removed by the pretreatment unit 1, the regulating tank 2 obtains a stable water volume and uniform water quality, and the anaerobic treatment unit 3 is an upflow AnMBR. The oxygen treatment unit 3 performs anaerobically treatment on the leachate flowing out of the regulating tank 2, uses anaerobic organisms to decompose organic matter in the sewage into small molecular substances and produce biogas, and removes small molecular organic matter in the leachate flowing out of the anaerobic treatment unit 3 through the aerated biological filter 4. The effluent of the aerated biological filter 4 is filtered through the nanofiltration membrane unit 5 to intercept salt and some organic matter to form concentrated water and produced water. The produced water meets the standards and is discharged. The effluent of the nanofiltration membrane unit 5 is concentrated and reduced by the reverse osmosis unit 6 to form secondary concentrated water and produced water. The produced water meets the standards and is discharged, thereby improving the recovery rate.

[0050] Compared with existing anaerobic treatment devices for leachate, this anaerobic treatment system has stable mud-water separation effect, high separation efficiency, low maintenance cost, strong pollutant retention capacity, ensures that organic matter and salt are discharged in compliance with standards, ensures stable water production flux and water quality, does not generate additional waste, and is more environmentally friendly.

[0051] The inventors tested the performance of the anaerobic leachate treatment system of this application and obtained the optimal operating data for the anaerobic treatment system. The optimal operating data are: a treatment temperature of approximately 35°C, a hydraulic retention time of 10 days, a system design sludge concentration of 30-60 g / L, a biogas yield of 0.45 m³ / kg (COD), a COD volumetric load of 4.5 kg / (m³·d), and a carbon source of sodium acetate or glucose. This achieves optimal organic matter decomposition efficiency and improves the biodegradability of landfill leachate.

[0052] In one embodiment of the present disclosure, see Figure 1The system also includes an anaerobic incineration unit 7, whose feed port is connected to one of the discharge ports of the anaerobic treatment unit 3 and the reverse osmosis unit 6, respectively, to incinerate the biogas and secondary concentrated water. This can reduce the pollution emissions of the anaerobic treatment system and be more environmentally friendly.

[0053] In one embodiment of the present disclosure, see Figure 1 The system also includes a sludge conditioning and drying unit 8, the feed inlet of which is connected to one of the discharge ports of the anaerobic treatment unit 3 and the biological aeration filter 4. The sludge conditioning and drying unit 8 is used to filter press the sludge discharged from the anaerobic treatment unit 3 and the biological aeration filter 4 to achieve mud-water separation. This further separates the landfill leachate from the water, improving the system's mud-water separation efficiency.

[0054] Optionally, the discharge port of the sludge conditioning and drying unit 8 is connected to the feed port of the garbage bin, and the dehydrated dry sludge is incinerated to avoid generating other wastes.

[0055] Optionally, before the sludge conditioning and drying unit 8 performs filter pressing on the sludge, PAM is added to the sludge to achieve rapid sludge-water separation, facilitate dehydration of the sludge, and reduce the moisture content of the dehydrated sludge.

[0056] Optionally, the sludge conditioning and drying unit 8 realizes sludge-water separation by plate and frame filter pressing.

[0057] Optionally, the moisture content of the dehydrated dry mud is not higher than 60%.

[0058] Optionally, the clear liquid generated after sludge dehydration is introduced into a reflow tank for collection and then pumped into the aerated biological filter 4 .

[0059] In one embodiment of the present disclosure, the pretreatment unit 1 uses a rotary drum screen machine and a primary sedimentation tank. Thus, the rotary drum screen machine filters the scum in the landfill leachate, and the primary sedimentation tank settles the suspended matter in the landfill leachate, thereby removing the larger suspended matter in the landfill leachate.

[0060] In one embodiment of the present disclosure, see Figure 2 and Figure 3The anaerobic treatment unit 3 includes: a tank body 9, a plurality of brackets 25 are evenly distributed on the outer wall of the tank body 9, a rotating shaft 10 is rotatably arranged in the tank body 9, the bottom end of the rotating shaft 10 extends out of the tank body 9 and is connected to the driven wheel 11; a diaphragm assembly 12, a plurality of diaphragm assemblies 12 are stacked together, arranged in the tank body 9, and sleeved on the rotating shaft 10; a drive motor 13, arranged on one side of the tank body 9, a driving wheel 14 is provided at the output end of the drive motor 13, and a belt is driven between the driving wheel 14 and the driven wheel 11; an anaerobic treatment tank 15, arranged on one side of the tank body 9, the discharge port of the anaerobic treatment tank 15 is connected to the feed port of the tank body 9 through a feed barrel 26, one discharge port of the tank body 9 is connected to the feed barrel 26, and an exhaust pipe 24 is connected to the anaerobic treatment tank 15; a water production barrel 27, arranged on one side of the tank body 9, the feed port of the water production barrel 27 is connected to the other discharge port of the tank body 9. In this way, most of the pollutants in the leachate are degraded through the anaerobic treatment tank 15, the filtrate containing a small amount of pollutants is transported to the tank body 9 through the feed barrel 26, and the small amount of pollutants is filtered out through multiple stacked membrane assemblies 12, thereby removing organic matter from the sewage.

[0061] Optionally, the biogas generated by the anaerobic treatment is directly discharged through the exhaust pipe 24 connected to the anaerobic treatment tank 15 and then directed to the anaerobic incineration unit 7 for combustion via a valve directional pipeline.

[0062] In one example, the diaphragm assembly 12 has a disc-plate structure.

[0063] Alternatively, see Figure 4 and Figure 5 The membrane assembly 12 includes a mounting frame 16, a filter plate 17 located in the center of the mounting frame 16, drainage brackets 18 located on either side of the filter plate 17, a filter membrane 19 located on the side of the drainage bracket 18 away from the filter plate 17, and a scraper 20 located above the filter membrane 19. The scraper 20 has an S-shaped cross-section, and the rotating shaft 10 passes through the center of the scraper 20 and is fixedly connected to the scraper 20. The scraper 20 has two through-slots, which are symmetrically arranged on either side of the rotating shaft 10. This allows for high-speed forced circulation cross-flow filtration generated by the rotation of the scraper 20, preventing the formation of a fouling layer on the surface of the filter membrane 19, reducing membrane fouling, and ensuring a stable water volume treated by the AnMBR.

[0064] Optionally, the flow rate of the membrane surface cross-flow generated by the rotation of the scraper 20 is 10-15 m / s and the temperature resistance is 80.

[0065] The inventors discovered that membrane fouling occurs, on the one hand, when wastewater particles, micelles, or certain solute molecules physically or chemically interact with the membrane during the filtration process, or when concentration polarization causes the solute to exceed its solubility on the membrane surface (this refers to the phenomenon in which, during the separation process, when the solution in the feed liquid is driven by pressure to pass through the membrane, the solute is retained, resulting in an increasingly high concentration at the interface between the membrane and the bulk solution or in the area near the membrane interface. Under the action of the concentration gradient, the solute will diffuse from the membrane surface into the bulk solution, forming a boundary layer, which increases fluid resistance and local osmotic pressure, resulting in a decrease in solvent permeation flux); on the other hand, adsorption and deposition on the inner and outer surfaces of the membrane caused by mechanical action cause the membrane pore size to become smaller or clogged, reducing membrane flux and separation performance, resulting in deposition on the inner and outer surfaces of the membrane. Therefore, membrane fouling can be divided into filter cake layer pollution deposited on the membrane surface and membrane pore blockage pollution. Therefore, the rotation of the scraper 20 generates forced circulation cross-flow filtration, and the high membrane surface flow rate avoids the formation of the pollution layer to the greatest extent, and destroys the formation of concentration polarization, so that the anti-pollution ability of the membrane assembly 12 is greatly improved, and it is suitable for the environment of high suspended solids and high organic matter concentration of anaerobic biogas slurry.

[0066] In one example, the filter membrane 19 is an amphoteric anti-pollution ion membrane, the pore size of the filter membrane 19 is 0.03 μm, and the molecular weight cut-off is 1000 Da.

[0067] Alternatively, the surface of an ordinary membrane is generally charged, and is easily electrostatically adsorbed and combined with charged pollutants in the landfill leachate, resulting in membrane pollution (generally, the membrane surface is mostly negatively charged. Under neutral pH conditions, organic pollutants such as humus and protein in water are mostly negatively charged. Therefore, a negative charge on the membrane surface is beneficial to reducing organic pollution. Studies have shown that negatively charged surfaces are prone to accumulate Ca2+, while positively charged surfaces are prone to attract negatively charged Ca3(PO4)2 particles. Uncharged membrane surfaces are more conducive to reducing Ca3(PO4)2 scaling). Therefore, the amphoteric anti-pollution ion membrane has undergone special modification treatment, and the membrane surface is uncharged, and has strong resistance to strong pollutants.

[0068] Alternatively, see Figure 4 and Figure 5 The membrane assembly 12 also includes a feed hole 21, a first liquid outlet hole 22, and a second liquid outlet hole 23. The feed hole 21 is connected to the upper filter membrane 19; the first liquid outlet hole 22 is connected to the filter plate 17; and the second liquid outlet hole 23 is connected to the filter membrane 19. Multiple feed holes 21 are stacked to form a feed pipe, multiple first liquid outlet holes 22 are stacked to form a first discharge pipe, and multiple second liquid outlet holes 23 are stacked to form a second discharge pipe. In this way, the water output from the feed barrel 26 can be transported to the membrane assembly 12 and distributed to the filter membrane 19 of each membrane assembly 12, facilitating the filtration of the water output from the feed barrel 26 and the discharge of the filtrate produced after filtration.

[0069] Alternatively, see Figure 3 The feed barrel 26 is connected to the feed pipe through a conveying pipe, the first discharge pipe is connected to the water production barrel 27 through a first external pipe, and the second discharge pipe is connected to the outside of the tank body 9 through a second external pipe.

[0070] Alternatively, see Figure 3 A three-way valve is installed at one end of the second external pipe located outside the tank body 9. One outlet of the three-way valve is connected to the drain pipe, and the other outlet of the three-way valve is connected to the feed barrel 26. The flow direction of the liquid in the second discharge pipe is controlled by the three-way valve.

[0071] It can be understood that the drive motor 13 is started to drive the rotating shaft 10 and the scraper 20 thereon to rotate, and the feed liquid anaerobically treated in the anaerobic treatment tank 15 is pumped into the tank body 9 and distributed to the filter membrane 19 of each membrane assembly 12 through the feed pipe. The filter membrane 19 filters the feed liquid, and the scraper 20 rotates at high speed to generate a high-speed cross-flow environment on the surface of the filter membrane 19. The water produced after the feed liquid is filtered by multiple filter membranes 19 is concentrated and transported to the water production barrel 27 for storage through the first discharge pipe, and the concentrated water left on the surface of the filter membrane 19 is discharged through the second discharge pipe.

[0072] It should be noted that the recovery rate of this anaerobic leachate treatment system must be higher than 50%. However, a single filtration pass of the membrane assembly 12 within the anaerobic treatment unit 3 hardly achieves a high recovery rate. Therefore, the membrane assembly 12 generally requires brine recirculation to meet the required filtrate recovery rate. To meet the required system recovery rate, a three-way valve is controlled to discharge a portion of the brine leaving the tank 9 through the drain pipe, while the remaining portion is recirculated into the feed barrel 26. This high proportion of brine recirculation improves the filtrate recovery rate, reduces the risk of contamination of the filter membrane 19, and thus reduces the recovery rate of the membrane assembly 12.

[0073] In one embodiment of the present disclosure, the filler in the biological aeration filter 4 is natural zeolite with a particle size of 3-5 mm. This reduces the investment cost of the biological aeration filter 4 and combines the excellent selective ion exchange properties of zeolite with the biochemical functions of the biological aeration filter 4, thereby achieving functions such as filtration and adsorption, ion exchange, biooxidation, and bioregeneration, ensuring that the final effluent ammonia nitrogen and total nitrogen levels meet stable standards.

[0074] It can be understood that after the landfill leachate is anaerobically treated by the anaerobic treatment unit 3, the large molecular refractory organic matter is decomposed into small molecular organic matter with high biodegradability. After the anaerobic treatment unit 3 efficiently separates the mud and water, the effluent of the anaerobic treatment unit 3 basically does not contain suspended matter, which not only meets the treatment capacity of the aerated biological filter 4, but also avoids the problem of filter blockage caused by suspended matter.

[0075] Optionally, the flow direction of the biological aeration filter 4 is upward biological filtration.

[0076] Optionally, the biological aeration filter 4 uses a special aeration head, which has the advantages of efficient oxygen supply, energy saving, safe use, easy operation and maintenance, etc.

[0077] Optionally, the biological aerated filter 4 adopts an "air + water" combined backwashing method.

[0078] In one embodiment of the present disclosure, the nanofiltration membrane unit 5 uses an NFDK nanofiltration membrane.

[0079] Optionally, the operating pressure of the NFDK nanofiltration membrane is 50 bar, the rejection rate of divalent ions is >98%, and the water recovery rate is 85%.

[0080] In one embodiment of the present disclosure, the reverse osmosis unit 6 uses a high-pressure disc-tube reverse osmosis membrane.

[0081] Optionally, the operating pressure of the high-pressure disc-tube reverse osmosis membrane is 160 bar, the salt rejection rate is >99%, and the water recovery rate is 60%.

[0082] In one example, the reverse osmosis unit 6 concentrates and reduces the effluent from the nanofiltration membrane unit 5, and the resulting secondary concentrated water can be used for fly ash solidification, lime slurrying, or furnace back-spraying.

[0083] In one embodiment of the present disclosure, both the NFDK nanofiltration membrane and the high-pressure disc-tube reverse osmosis membrane are pressure-driven membranes (the solvent migrates against the concentration gradient through the NF / RO membrane separation under a certain pressure, and the separated water production includes H2O and other small molecules. The remaining substances and water are further processed in the form of a concentrated liquid). By combining the nanofiltration membrane unit 5 with the reverse osmosis unit 6, the amount of water going to the anaerobic incineration unit 7 is reduced, the recovery rate of the membrane unit is improved, the operating load of the reverse osmosis unit 6 is reduced, and the investment cost of the reverse osmosis unit 6 and the heat loss of the anaerobic incineration unit 7 are reduced.

[0084] In the embodiments of the present disclosure, see Figures 1 to 5 The working process of the anaerobic treatment system for landfill leachate is briefly described as follows:

[0085] When the present invention is used, the landfill leachate to be treated is first pumped to the pretreatment unit 1, and the larger suspended solids in the landfill leachate are removed through the rotary drum screen machine and the primary sedimentation tank, and the landfill leachate is introduced into the regulating tank 2 through the pipeline. The regulating tank 2 obtains a relatively stable water volume and uniform water quality. The effluent from the regulating tank 2 is pumped to the anaerobic treatment unit 3 through a quantitative pump, and most of the pollutants are degraded by the anaerobic microorganisms in the anaerobic treatment tank 15. The anaerobic organisms are used to decompose the organic matter in the sewage into small molecular substances, such as methane, water, etc. A small part of the pollutants is filtered and removed by multiple membrane assemblies 12 stacked together. The liquid after anaerobically treated in the anaerobic treatment tank 15 is pumped into the feed barrel 26, and then pumped from the feed barrel 26 into the tank body 9, and distributed to each layer of the filter membrane 19 through the feed pipe. The liquid is filtered by the filter membrane 19, and the drive motor 13 drives the scraper 20 to rotate at high speed, thereby generating a high-speed cross-flow environment on the surface of the filter membrane 19. The produced water after filtration by the membrane 19 is concentrated and transported to the water production tank 27 through the first discharge pipe. The remaining concentrated water is discharged through the drain pipe according to the concentration ratio using a three-way valve, and the other part is returned to the feed tank 26. The biogas produced by anaerobic treatment is sent to the anaerobic incineration unit 7 through the exhaust pipe 24 and the valve directional pipeline for combustion treatment. The effluent of the anaerobic treatment unit 3 is treated by the aerated biological filter 4 to further remove small molecular organic matter. The effluent of the aerated biological filter 4 is passed through the nanofiltration membrane unit 5 to intercept salt and some organic matter to form concentrated water. The produced water meets the standards and is discharged. The concentrated water of the nanofiltration membrane unit 5 is further reduced by the reverse osmosis unit 6 to form secondary concentrated water. The produced water meets the standards and is discharged to improve the recovery rate. The secondary concentrated water is sent to the anaerobic incineration unit 7 for combustion treatment. The sludge discharged from the anaerobic treatment unit 3 and the aerated biological filter 4 is sent to the sludge conditioning and drying unit 8 for filter pressure treatment. The dehydrated dry sludge is sent to the garbage bin for incineration treatment.

[0086] The inventors tested the effluent quality of each unit in the anaerobic leachate treatment system, and the test results are shown in Table 1. These test results further demonstrate that the anaerobic leachate treatment system can improve the mud-water separation and efficiency of leachate, has a strong pollutant retention capacity, ensures that organic matter and salt discharge meet standards, maintains stable water flux and quality, generates no additional waste, and is more environmentally friendly.

[0087]

[0088] Table 1

[0089] Other embodiments of the present disclosure will readily occur to those skilled in the art after considering the specification and practicing the utility model disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A landfill leachate anaerobic treatment system, characterized in that: The system comprises a pretreatment unit (1), a regulating tank (2), an anaerobic treatment unit (3), an aerated biological filter (4), a nanofiltration membrane unit (5) and a reverse osmosis unit (6) which are connected in sequence; The pretreatment unit (1) is used to remove larger suspended solids in the landfill leachate; The anaerobic treatment unit (3) is used to perform anaerobically treatment on the landfill leachate to decompose organic matter and generate biogas; The aerated biological filter (4) is used to remove small molecular organic matter in the landfill leachate treated by the anaerobic treatment unit (3); The nanofiltration membrane unit (5) is used to filter the landfill leachate treated by the biological aeration filter (4) to form concentrated water and produced water; The reverse osmosis unit (6) is used to concentrate the concentrated water to form secondary concentrated water and produced water.

2. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The system further comprises an anaerobic incineration unit (7), the feed port of the anaerobic incineration unit (7) being connected to one of the discharge ports of the anaerobic treatment unit (3) and the reverse osmosis unit (6) respectively, so as to incinerate the biogas and the secondary concentrated water.

3. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The system further comprises a sludge conditioning and drying unit (8), wherein the feed port of the sludge conditioning and drying unit (8) is respectively connected to one of the discharge ports of the anaerobic treatment unit (3) and the aerated biological filter (4); The sludge conditioning and drying unit (8) is used to perform filter press treatment on the sludge discharged from the anaerobic treatment unit (3) and the biological aeration filter (4) to achieve mud-water separation.

4. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The pretreatment unit (1) adopts a rotary drum screen machine and a primary sedimentation tank.

5. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The anaerobic treatment unit (3) comprises: A tank body (9), wherein a plurality of brackets (25) are evenly distributed on the outer wall of the tank body (9), a rotating shaft (10) is rotatably provided in the tank body (9), and the bottom end of the rotating shaft (10) extends out of the tank body (9) and is connected to a driven wheel (11); A diaphragm assembly (12), wherein a plurality of the diaphragm assemblies (12) are stacked together, arranged in the tank body (9), and sleeved on the rotating shaft (10); A driving motor (13) is provided on one side of the tank body (9); a driving wheel (14) is provided at the output end of the driving motor (13); and a belt is used to transmit power between the driving wheel (14) and the driven wheel (11); An anaerobic treatment tank (15) is provided on one side of the tank body (9), wherein the discharge port of the anaerobic treatment tank (15) is connected to the feed port of the tank body (9) via a feed barrel (26), one discharge port of the tank body (9) is connected to the feed barrel (26), and an exhaust pipe (24) is connected to the anaerobic treatment tank (15); The water production barrel (27) is arranged on one side of the tank body (9), and the feed port of the water production barrel (27) is connected to another discharge port of the tank body (9).

6. The anaerobic treatment system for landfill leachate according to claim 5, characterized in that: The membrane assembly (12) comprises a mounting frame (16), a filter plate (17) located in the middle of the mounting frame (16), drainage brackets (18) located on both sides of the filter plate (17), a filter membrane (19) located on a side of the drainage bracket (18) away from the filter plate (17), and a scraper (20) located above the filter membrane (19); The cross section of the scraper (20) is S-shaped, the rotating shaft (10) passes through the center of the scraper (20) and is fixedly connected to the scraper (20), and two through grooves are provided on the scraper (20), and the two through grooves are symmetrically arranged on both sides of the rotating shaft (10).

7. The anaerobic treatment system for landfill leachate according to claim 6, characterized in that: The diaphragm assembly (12) further includes a feed hole (21), a first liquid outlet hole (22), and a second liquid outlet hole (23); The feed hole (21) is in communication with the upper filter membrane (19); The first liquid outlet (22) is in communication with the filter plate (17); The second liquid outlet (23) is in communication with the filter membrane (19); A plurality of the feed holes (21) are stacked to form a feed pipe, a plurality of the first liquid outlet holes (22) are stacked to form a first discharge pipe, and a plurality of the second liquid outlet holes (23) are stacked to form a second discharge pipe.

8. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The filler of the biological aeration filter (4) is natural zeolite, and the particle size of the natural zeolite is 3-5 mm.

9. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The nanofiltration membrane unit (5) adopts an NFDK type nanofiltration membrane.

10. The anaerobic treatment system for landfill leachate according to claim 1, characterized in that: The reverse osmosis unit (6) adopts a high-pressure disc-tube reverse osmosis membrane.

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