High-efficiency biological treatment system and treatment method for landfill leachate

Abstract

The invention belongs to the technical field of garbage treatment, and particularly relates to an efficient biological treatment system and method for garbage leachate. The system comprises a primary nitrification and denitrification treatment subsystem, a secondary nitrification and denitrification treatment subsystem, efficient membrane biological reaction equipment and an ultrafiltration unit which are connected in sequence, the primary nitrification and denitrification treatment subsystem comprises primary denitrification treatment equipment and nitrification primary denitrification equipment; the secondary nitrification and denitrification treatment subsystem comprises secondary denitrification treatment equipment and nitrification deep denitrification equipment; a temperature control device is arranged in each of the nitrification primary denitrification device and the nitrification deep denitrification device to control the nitrification reaction temperature; a membrane cleaning assembly is arranged in the efficient membrane biological reaction equipment. When the system is used for treating the landfill leachate, the required energy consumption can be effectively reduced, the treatment efficiency of the landfill leachate is improved, and the cleanliness of the landfill leachate treated by the reaction tank is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of garbage treatment, and in particular relates to a high-efficiency biological treatment system and method for garbage leachate. Background Art

[0002] Leachate is a high-concentration organic wastewater formed during the stacking and landfilling process of landfills due to the moisture inside the garbage and the rainwater and snow water that penetrate into the landfill after being filtered through the garbage layer and the covering soil layer. This wastewater has a complex composition, contains high concentrations of organic pollutants and heavy metals, is dark in color and has strong toxicity. If not properly handled, it will not only pollute surface water, but may also infiltrate into groundwater, causing serious environmental pollution. The characteristics of leachate vary with local climatic conditions and the use time of the landfill, making its treatment a difficult problem in the design, operation and management of landfills. With the improvement of residents' living standards and the continuous increase in the amount of urban garbage, many areas have to build more landfills and incineration plants. The problem of leachate treatment has become more serious and has become an environmental challenge that needs to be solved urgently.

[0003] The concentration of organic pollutants in landfill leachate is very high, and its water quality composition is very complex, containing a variety of organic pollutants, such as ammonia nitrogen, heavy metals, hydrogen sulfide and a large amount of organic matter. At present, the treatment of ammonia nitrogen mainly relies on nitrification and denitrification processes. However, in the denitrification stage, heavy metals and sulfides in sewage will inhibit the microorganisms in the reactor and affect the effect of anaerobic treatment. In addition, the nitrification and denitrification process will not only produce nitrogen, but also release some volatile organic compounds. These volatile organic compounds are difficult to remove by conventional methods such as water washing. They not only pollute the environment, but also affect the performance and treatment efficiency of the membrane in the subsequent membrane bioreactor treatment stage. Summary of the invention

[0004] In order to overcome the problems existing in the background technology, the present invention provides a high-efficiency biological treatment system and method for landfill leachate, which can not only improve the overall efficiency of leachate purification, but also improve the treatment efficiency of landfill leachate, greatly improve the removal of organic pollutants, and increase the cleanliness of landfill leachate treated in the reaction tank.

[0005] In order to achieve the above technical objectives, the present invention provides the following technical solutions:

[0006] A high-efficiency biological treatment system for landfill leachate, the system comprising a primary nitrification and denitrification treatment subsystem, a secondary nitrification and denitrification treatment subsystem, a high-efficiency membrane bioreactor, and an ultrafiltration unit connected in sequence;

[0007] The primary nitrification and denitrification treatment subsystem includes a primary denitrification treatment device and a nitrification primary denitrification device; the secondary nitrification and denitrification treatment subsystem includes a secondary denitrification treatment device and a nitrification deep denitrification device; the primary nitrification and denitrification treatment subsystem and the secondary nitrification and denitrification treatment subsystem have a two-stage denitrification rate of more than 99.3% for total nitrogen removal;

[0008] A temperature control device is respectively arranged in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment to control the nitrification reaction temperature; and a membrane cleaning component is arranged in the high-efficiency membrane biological reaction equipment.

[0009] Furthermore, the primary denitrification treatment equipment, the nitrification primary denitrification equipment, the secondary denitrification treatment equipment, the nitrification deep denitrification equipment, the high-efficiency membrane bioreactor equipment, and the ultrafiltration unit are sequentially arranged along the flow direction of the wastewater.

[0010] Furthermore, a first internal reflux pipeline is provided between the nitrification primary denitrification equipment and the primary denitrification treatment equipment, and the internal reflux liquid generated by the nitrification primary denitrification equipment is returned to the primary denitrification treatment equipment through the first internal reflux pipeline;

[0011] A second internal reflux pipeline is arranged between the secondary denitrification treatment equipment and the nitrification deep denitrification equipment, and the internal reflux liquid generated by the nitrification deep denitrification equipment is returned to the secondary denitrification treatment equipment through the second internal reflux pipeline.

[0012] Furthermore, the temperature control device includes a cooling water pipe, a water tank, a first circulating water pipe, a second circulating pipe, a cooling box, and a water pump which are wound and fixed on the outer wall of the nitrification tank; the water outlet of the water tank is connected to one end of the first circulating water pipe, the other end of the first circulating water pipe is connected to the inlet of the cooling water pipe, the outlet of the cooling water pipe is connected to the cooling box, and the cooling box and the water tank are connected through the second circulating pipe; the water pump is arranged on the first circulating water pipe.

[0013] Furthermore, the temperature control device is used to control the nitrification reaction temperature of the digestion tank in the nitrification primary denitrification device and the nitrification deep denitrification device at 30-32°C.

[0014] Furthermore, the high-efficiency membrane bioreactor equipment includes a reaction tank, a water inlet pump, a filter wall, a membrane cleaning component, a membrane component, a water outlet pump, a sludge pump, and a sludge tank;

[0015] The water inlet pump is arranged at one end of the reaction tank, and the water outlet pump is arranged at the other end of the reaction tank; in the reaction tank, the filter wall and the membrane assembly are arranged in sequence along the flow direction of the wastewater; the membrane assembly includes a plurality of permeable membranes, and the permeable membranes are vertically arranged in the reaction tank;

[0016] The sludge pool is arranged directly below the reaction pool, a mounting plate is arranged between the sludge pool and the reaction pool, a sinking hole is arranged on the mounting plate, sludge in the sludge pool flows into the sludge pool through the sinking hole, and the sludge pump is arranged at the outlet of the sludge pool.

[0017] Furthermore, a plurality of filtering and retaining channels are arranged through the filtering wall, each filtering and retaining channel comprises a filtering hole and a retaining hole which are interconnected; the filtering hole is arranged on the water-facing surface, the retaining hole is arranged on the water-receiving surface, and the aperture of the retaining hole is larger than the aperture of the filtering hole;

[0018] The sludge pool is in the shape of a square frustum and is used to hold the sludge intercepted by the filter wall and the sludge washed from the membrane assembly by the membrane cleaning assembly.

[0019] Furthermore, the membrane cleaning assembly is used to clean the sludge on the membrane assembly; the membrane cleaning assembly is arranged above the membrane assembly;

[0020] The membrane cleaning assembly includes a plurality of fixed plates, a driving assembly and a cleaning brush; one or more fixed plates are arranged between two adjacent permeable membranes; the fixed plates and the permeable membranes are arranged in parallel; a cleaning brush is arranged on both sides of each fixed plate;

[0021] All the fixed plates are connected to the driving assembly; the driving assembly is used to drive all the fixed plates to move up and down.

[0022] A method for efficiently biologically treating landfill leachate, comprising the following steps:

[0023] (1) The landfill leachate enters the primary denitrification treatment equipment for treatment and then enters the nitrification primary denitrification equipment, and the reflux liquid in the nitrification primary denitrification equipment returns to the primary denitrification treatment equipment;

[0024] Repeat the internal reflux until the chemical oxygen demand (COD) of the landfill leachate treated by the primary nitrification and denitrification treatment subsystem is less than 200 mg / L, the ammonia nitrogen content is less than 20 mg / L, the total nitrogen content is less than 50 mg / L, and it is stable within the requirements within 1 hour. Then stop the internal reflux and the landfill leachate water enters the secondary nitrification and denitrification treatment subsystem;

[0025] (2) The landfill leachate treated by the primary denitrification treatment equipment enters the secondary denitrification treatment equipment in the secondary nitrification and denitrification treatment subsystem for treatment, and then enters the nitrification deep denitrification equipment. The internal reflux liquid of the nitrification deep denitrification equipment returns to the secondary denitrification treatment equipment; the internal reflux is repeated until the chemical oxygen demand COD of the landfill leachate treated by the secondary nitrification and denitrification treatment subsystem is less than 100 mg / L, the ammonia nitrogen content is less than 10 mg / L, the total nitrogen content is less than 20 mg / L and is stable within the requirements within 1 hour, then the internal reflux is stopped, and the landfill leachate water enters the high-efficiency membrane biological reactor;

[0026] (3) The high-efficiency membrane bioreactor equipment filters the incoming high-efficiency membrane bioreactor leachate to remove sludge; then it enters the ultrafiltration unit for treatment. The COD removal rate of the effluent water quality of the ultrafiltration unit reaches 93.3%, the ammonia nitrogen removal rate reaches 99.6%, and the total nitrogen removal rate reaches more than 99.3%.

[0027] Furthermore, in step (1) and step (2), the nitrification reaction temperature of the digester in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment is controlled at 30-32°C.

[0028] The beneficial effects of the present invention are:

[0029] The high-efficiency biological treatment system for landfill leachate provided by the present invention combines a two-stage nitrification and denitrification treatment system with a membrane biological reaction treatment, and sets a temperature control device in the two-stage nitrification and denitrification system to increase the nitrification reaction rate and the landfill leachate treatment speed;

[0030] The high-efficiency biological treatment system for landfill leachate provided by the present invention sets a cleaning component in the high-efficiency membrane bioreactor to reduce the adhesion of sludge on the permeable membrane, thereby increasing the flow rate of leachate treated by the high-efficiency membrane bioreactor per unit time.

[0031] Compared with the prior art, the effluent water quality of the high-efficiency biological treatment system for landfill leachate provided by the present invention is high-quality and stable, the effluent water is free of bacteria and suspended solids, the sludge load is low, and the residual sludge output is small; it can effectively degrade the main pollutants COD, BOD, ammonia nitrogen, and total nitrogen without secondary pollution, greatly improving the treatment effect and efficiency of landfill leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of a high-efficiency biological treatment system for landfill leachate according to an embodiment of the present invention;

[0033] Figure 2 It is a schematic diagram of the structure of the temperature control device in an embodiment of the present invention;

[0034] Figure 3This is a schematic diagram of the structure of a high-efficiency membrane bioreactor in an embodiment of the present invention;

[0035] Figure 4 Schematic diagram of the structure of the membrane cleaning assembly in an embodiment of the present invention;

[0036] Figure 5 is a partial cross-sectional view of the filter wall in the transverse direction in an embodiment of the present invention;

[0037] Figure numerals: 1. nitrification tank; 2. temperature control equipment; 21. cooling water pipe; 22. water tank; 23. first circulation water pipe; 24. second circulation pipe; 25. cooling tank; 26. water pump; 3. high-efficiency membrane biological reaction equipment; 31. reaction tank; 32. water inlet pump; 33. filter wall; 34. membrane cleaning assembly; 35. membrane assembly; 36. water outlet pump; 37. sludge pump; 38. sludge tank; 331. filter hole; 332. retention hole; 341. fixing plate; 342. driving assembly; 343. cleaning brush. DETAILED DESCRIPTION

[0038] The technical solution of the present invention is further described below in conjunction with specific embodiments and drawings.

[0039] A highly efficient biological treatment system for landfill leachate, such as Figure 1 As shown, the system includes a primary nitrification and denitrification treatment subsystem, a secondary nitrification and denitrification treatment subsystem, a high-efficiency membrane bioreactor, and an ultrafiltration unit connected in sequence;

[0040] The primary nitrification and denitrification treatment subsystem includes a primary denitrification treatment device and a nitrification primary denitrification device; the secondary nitrification and denitrification treatment subsystem includes a secondary denitrification treatment device and a nitrification deep denitrification device; the primary nitrification and denitrification treatment subsystem and the secondary nitrification and denitrification treatment subsystem have a two-stage denitrification rate of more than 99.3% for total nitrogen removal;

[0041] A temperature control device is respectively arranged in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment; and a membrane cleaning component is arranged in the high-efficiency membrane biological reaction equipment.

[0042] In this embodiment, the primary denitrification treatment equipment, the nitrification primary denitrification equipment, the secondary denitrification treatment equipment, the nitrification deep denitrification equipment, the high-efficiency membrane bioreactor equipment, and the ultrafiltration unit are arranged in sequence along the wastewater flow direction.

[0043] In this embodiment, a first internal reflux pipeline is provided between the nitrification primary denitrification equipment and the primary denitrification treatment equipment, and the internal reflux liquid generated by the nitrification primary denitrification equipment is returned to the primary denitrification treatment equipment through the first internal reflux pipeline;

[0044] A second internal reflux pipeline is arranged between the secondary denitrification treatment equipment and the nitrification deep denitrification equipment, and the internal reflux liquid generated by the nitrification deep denitrification equipment is returned to the secondary denitrification treatment equipment through the second internal reflux pipeline.

[0045] In this embodiment, if Figure 2 As shown, the temperature control device 2 includes a cooling water pipe 21, a water tank 22, a first circulating water pipe 23, a second circulating pipe 24, a cooling box 25, and a water pump 26 which are wound and fixed on the outer wall of the nitrification tank 1; the water outlet of the water tank 22 is connected to one end of the first circulating water pipe 23, the other end of the first circulating water pipe 23 is connected to the inlet of the cooling water pipe 21, the outlet of the cooling water pipe 21 is connected to the cooling box 25, and the cooling box 25 and the water tank 22 are connected through the second circulating pipe 24; the water pump 26 is arranged on the first circulating water pipe 23.

[0046] The nitrification tank is a nitrification tank in a nitrification primary denitrification device or a nitrification deep denitrification device; the cooling water pipe is wound around the outer wall of the nitrification tank and fixedly connected; the nitrification tank is arranged horizontally, and the bottom of the nitrification tank is fixedly connected to the ground. A thermometer is arranged in the digestion tank, and the opening or closing of the temperature control device is determined by the value of the thermometer.

[0047] In the present invention, water in the water tank flows along the circulating water pipe, and the water flows from the water tank to the outside of the nitrification pool. Since the cooling water pipe is wound around the outside of the nitrification pool, the water absorbs the heat generated by the nitrification reaction when it flows to the nitrification pool, and the water cools the nitrification pool. Then the water flows into the cooling box with the heat, and the cooling box cools the water flow. The cooled water re-enters the water tank, and then the water flow circulates to absorb heat and cool, saving water resources and improving the utilization rate of the water flow. At the same time, due to the setting of the cooling box, the heat generated in the nitrification pool is absorbed, and the heat is dissipated in time, so that the nitrification reaction in the nitrification pool proceeds normally, achieving the effect of improving the denitrification efficiency of the garbage leachate. Specifically, the cooling box includes a heat conducting pipe, which is fixedly connected to the cooling box, and both ends of the heat conducting pipe are connected to the circulating water pipe. The circulating water pipe passes through the heat conducting pipe, and the heat conducting pipe extracts the heat of the water flow in the circulating water pipe, thereby improving the cooling effect on the water flow in the circulating water pipe and achieving the purpose of rapidly cooling the water flow. The meandering arrangement of the heat conducting pipe increases the length of the heat conducting pipe, thereby increasing the flow path of the water in the cooling box, extending the cooling time of the water in the circulating water pipe, and enabling the cooling box to have a better cooling effect on the circulating water.

[0048] In this embodiment, the temperature control device is used to control the nitrification reaction temperature of the digestion tank in the nitrification primary denitrification device and the nitrification deep denitrification device at 30-32° C. The temperature control device is used to absorb the heat generated in the nitrification tank, so that the nitrification reaction in the nitrification tank proceeds normally, thereby achieving the effect of improving the denitrification efficiency of the garbage leachate.

[0049] In this embodiment, if Figure 3 As shown, the high-efficiency membrane biological reaction equipment 3 includes a reaction tank 31, a water inlet pump 32, a filter wall 33, a membrane cleaning component 34, a membrane component 35, a water outlet pump 36, a sludge pump 37, and a sludge tank 38;

[0050] The water inlet pump 32 is arranged at one end of the reaction tank 31, and the water outlet pump 36 is arranged at the other end of the reaction tank 31; in the reaction tank 31, along the flow direction of the wastewater, the filter wall 33 and the membrane assembly 35 are arranged in sequence; the membrane assembly 35 includes a plurality of permeable membranes, and the permeable membranes are vertically arranged in the reaction tank 31;

[0051] The sludge pool 38 is arranged directly below the reaction pool 31, a mounting plate is arranged between the sludge pool 38 and the reaction pool 31, a sink hole is arranged on the mounting plate, and the sludge in the sludge pool 38 flows into the sludge pool through the sink hole; a sludge pump 37 is arranged at the outlet of the sludge pool 38; specifically, the sludge pool 7 is in the shape of a square cone, and is used to hold the sludge intercepted by the filter wall and the sludge washed from the membrane assembly;

[0052] A plurality of filtering and retaining channels are arranged through the filter wall 33, each of which includes a filtering hole 331 and a retaining hole 332 that are interconnected; the filtering hole 331 is arranged on the water-facing side, and the retaining hole 332 is arranged on the water-retaining side, and the aperture of the retaining hole 332 is larger than the aperture of the filtering hole 331; preferably, the aperture range of the filtering hole is 4-6mm, preferably 5mm, and the aperture range of the retaining hole 332 is 7-9mm; the retaining hole 332 is arranged on the water-retaining side and has an aperture larger than the aperture of the filtering hole 331, and the angle formed at the connection between the filtering hole and the retaining hole is conducive to the retention of nitrite bacteria and nitrifying bacteria with a longer generation period in the filter wall.

[0053] In this embodiment, the membrane cleaning assembly 34 is used to clean the sludge on the membrane assembly 35; the membrane cleaning assembly 34 is arranged above the membrane assembly 35;

[0054] like Figure 3 As shown, the membrane cleaning assembly 34 includes a plurality of fixed plates 341, a driving assembly 342 and a cleaning brush 343; one or more fixed plates 341 are arranged between two adjacent permeable membranes; the fixed plates 341 and the permeable membranes are arranged in parallel; a cleaning brush 343 is arranged on both sides of each fixed plate 341;

[0055] All the fixing plates 341 are connected to the driving assembly 342; the driving assembly 342 is used to drive all the fixing plates 341 to move up and down.

[0056] Specifically, the permeable membranes in the membrane assembly 35 are arranged in groups of two, one or more fixed plates are arranged in the middle of each group of permeable membranes, and a cleaning brush is fixedly arranged on the two sides of each fixed plate close to the permeable membrane;

[0057] The driving assembly 342 includes a plurality of transmission shafts and a plurality of first bevel gears arranged on the transmission shafts; and the driving assembly 342 also includes a plurality of supporting components for supporting the transmission shafts, and the supporting components are arranged on the side walls of the reaction pool 31;

[0058] Specifically, a threaded rod with a threaded surface is fixedly connected above each fixed plate; a second bevel gear is arranged on the threaded rod; the first bevel gear and the second bevel gear are vertically meshed and connected with each other; when the transmission shaft is rotated, the first bevel gear rotates and drives the second bevel gear to rotate, thereby driving the threaded rod and the fixed plate under the threaded rod to move up and down.

[0059] In the present invention, a membrane cleaning assembly is arranged on the membrane assembly. A plurality of membrane cleaning assemblies are arranged respectively between adjacent permeable membranes. The membrane cleaning assembly includes a fixed plate, a cleaning brush and a driving member. The fixed plate is arranged between adjacent permeable membranes. The fixed plate is arranged parallel to the membrane assembly. The cleaning brush is fixedly connected to the side of the fixed plate. The surface of the cleaning brush abuts against the surface of the membrane. The driving assembly is used to drive the fixed plate to move upward or downward. The driving assembly is started to move the fixed plate up and down, so that the cleaning brush brushes the membrane surface up and down. The arrangement of the cleaning brush can not only brush off the sludge attached to the membrane, but also make the garbage filtrate fully contact with the membrane assembly, thereby reducing the adhesion of sludge, improving the filtering capacity of the membrane, and increasing the flow rate of the leachate processed per unit time. There are two cleaning brushes arranged in conjunction with each fixed plate, which are fixedly connected to the two sides of the fixed plate respectively. Since the distance between adjacent permeable membranes is small, cleaning brushes are fixedly connected on both sides of the fixed plate. When the fixed plate moves upward or downward under the action of the driving member, the two cleaning brushes can brush the adjacent sides of the permeable membrane at the same time, reducing the brushing frequency of the cleaning brushes and increasing the rate of removing sludge on the membrane, thereby reducing the adhesion of sludge on the membrane and increasing the flow rate of leachate treated by the membrane per unit time. A sludge pool is fixedly set at the bottom of the membrane assembly, and a mounting plate is set on the top surface of the sludge pool. A sludge pump is connected to the sludge pool. The sludge intercepted by the filter wall and the sludge washed on the membrane will flow into the sludge pool along the sinking holes on the mounting plate, and then the sludge in the sludge pool will be discharged by the sludge pump to clean the sludge in the sludge pool.

[0060] The setting of the filter wall, filter holes and cleaning components will reduce the sludge content of the leachate when it passes through the membrane component, thereby reducing the adhesion of sludge on the membrane, thereby increasing the flow rate of the leachate treated by the membrane per unit time; the setting of the retention holes on the back of the filter wall is conducive to the retention of nitrite bacteria and nitrifying bacteria with a longer generation period in the reactor, so that the ammonia nitrogen in the leachate can be more fully nitrified, thereby improving the cleanliness of the leachate treated in the reaction tank; the setting of the fixed plate, cleaning brush and driving parts can clean the sludge on the membrane, thereby reducing the adhesion of sludge on the membrane, thereby increasing the rate of leachate treatment by the membrane per unit time.

[0061] Example 2: A highly efficient biological treatment method for landfill leachate, using the treatment system described in Example 1, the method comprises the following steps:

[0062] (1) The landfill leachate enters the primary denitrification treatment equipment for treatment and then enters the nitrification primary denitrification equipment, and the reflux liquid in the nitrification primary denitrification equipment returns to the primary denitrification treatment equipment;

[0063] Repeat the internal reflux until the chemical oxygen demand (COD) of the landfill leachate treated by the primary nitrification and denitrification treatment subsystem is less than 200 mg / L, the ammonia nitrogen content is less than 20 mg / L, the total nitrogen content is less than 50 mg / L, and it is stable within the requirements within 1 hour, that is, the chemical oxygen demand (COD) of the landfill leachate within 1 hour is less than 200 mg / L, the ammonia nitrogen content is less than 20 mg / L, and the total nitrogen content is less than 50 mg / L. At this time, it is considered that the water quality is stable and meets the water inlet requirements of the secondary nitrification and denitrification treatment subsystem, and the internal reflux is stopped, and the landfill leachate water enters the secondary nitrification and denitrification treatment subsystem;

[0064] (2) The landfill leachate treated by the primary denitrification treatment equipment enters the secondary denitrification treatment equipment in the secondary nitrification and denitrification treatment subsystem for treatment, and then enters the nitrification deep denitrification equipment. The internal reflux liquid of the nitrification deep denitrification equipment returns to the secondary denitrification treatment equipment; the internal reflux is repeated until the chemical oxygen demand (COD) of the landfill leachate treated by the secondary nitrification and denitrification treatment subsystem is less than 100 mg / L, the ammonia nitrogen content is less than 10 mg / L, the total nitrogen content is less than 20 mg / L, and it is stable within the requirements within 1 hour, that is, the chemical oxygen demand (COD) of the landfill leachate within 1 hour is less than 100 mg / L, the ammonia nitrogen content is less than 10 mg / L, and the total nitrogen content is less than 20 mg / L. At this time, it is considered that the water quality is stable and meets the water inlet requirements of the high-efficiency membrane biological reactor system, and the internal reflux is stopped, and the landfill leachate water enters the high-efficiency membrane biological reactor;

[0065] (3) The high-efficiency membrane bioreactor equipment filters the incoming high-efficiency membrane bioreactor leachate to remove sludge; then it enters the ultrafiltration unit for treatment. The COD removal rate of the effluent water quality of the ultrafiltration unit reaches 93.3%, the ammonia nitrogen removal rate reaches 99.6%, and the total nitrogen removal rate reaches more than 99.3%.

[0066] In step (1) and step (2), the nitrification reaction temperature of the digester in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment is controlled at 30-32°C.

[0067] Experimental analysis: The effluent effect of the high-efficiency biological treatment system for landfill leachate provided by the present invention is shown in Table 1. Through the two-stage biological denitrification process, the COD removal rate in the biochemical stage reaches 93.3%, the ammonia nitrogen removal rate reaches 99.6%, and the total nitrogen removal rate reaches more than 99.3%.

[0068] Table 1 Water quality of inlet and outlet water in high-efficiency biological treatment system for landfill leachate

[0069]

[0070]

[0071] The high-efficiency biological treatment system for landfill leachate provided by the present invention adopts two-stage biological denitrification, which ensures the effective removal of total nitrogen from the source, focuses on the total nitrogen compliance, and the application of two-stage biological denitrification, especially the application of secondary deep denitrification, deeply denitrifies the small amount of nitrate nitrogen remaining in the primary biological denitrification, and ensures that the final effluent total nitrogen complies with the compliance standard to the greatest extent. The two-stage nitrification and denitrification treatment system and the membrane module combined process enable the reactor to have extremely strong biological denitrification capacity and organic pollutant degradation capacity, and the reactor volume is relatively small, which effectively reduces the floor space and civil engineering investment, and has extremely strong feasibility and promotion in landfill applications.

[0072] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A highly efficient biological treatment system for landfill leachate, characterized in that: The system comprises a primary nitrification and denitrification treatment subsystem, a secondary nitrification and denitrification treatment subsystem, a high-efficiency membrane bioreactor, and an ultrafiltration unit connected in sequence; The primary nitrification and denitrification treatment subsystem includes a primary denitrification treatment device and a nitrification primary denitrification device; The secondary nitrification and denitrification treatment subsystem includes secondary denitrification treatment equipment and nitrification deep denitrification equipment; the removal rate of total nitrogen by the two-stage denitrification of the primary nitrification and denitrification treatment subsystem and the secondary nitrification and denitrification treatment subsystem reaches more than 99.3%; A temperature control device is respectively arranged in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment to control the nitrification reaction temperature; and a membrane cleaning component is arranged in the high-efficiency membrane biological reaction equipment.

2. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: The primary denitrification treatment equipment, the nitrification primary denitrification equipment, the secondary denitrification treatment equipment, the nitrification deep denitrification equipment, the high-efficiency membrane bioreactor equipment, and the ultrafiltration unit are sequentially arranged along the flow direction of the wastewater.

3. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: A first internal reflux pipeline is provided between the nitrification primary denitrification equipment and the primary denitrification treatment equipment, and the internal reflux liquid generated by the nitrification primary denitrification equipment is returned to the primary denitrification treatment equipment through the first internal reflux pipeline; A second internal reflux pipeline is arranged between the secondary denitrification treatment equipment and the nitrification deep denitrification equipment, and the internal reflux liquid generated by the nitrification deep denitrification equipment is returned to the secondary denitrification treatment equipment through the second internal reflux pipeline.

4. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: The temperature control device (2) comprises a cooling water pipe (21) wound and fixed on the outer wall of the nitrification tank (1), a water tank (22), a first circulating water pipe (23), a second circulating water pipe (24), a cooling box (25), and a water pump (26); the water outlet of the water tank (22) is connected to one end of the first circulating water pipe (23), the other end of the first circulating water pipe (23) is connected to the inlet of the cooling water pipe (21), the outlet of the cooling water pipe (21) is connected to the cooling box (25), and the cooling box (25) and the water tank (22) are connected via the second circulating water pipe (24); the water pump (26) is arranged on the first circulating water pipe (23).

5. The high-efficiency biological treatment system for landfill leachate according to claim 4 is characterized in that: The temperature control device is used to control the nitrification reaction temperature of the digestion tank in the nitrification primary denitrification device and the nitrification deep denitrification device at 30-32°C.

6. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: The high-efficiency membrane bioreactor (3) comprises a reaction tank (31), a water inlet pump (32), a filter wall (33), a membrane cleaning assembly (34), a membrane assembly (35), a water outlet pump (36), a sludge pump (37), and a sludge tank (38); The water inlet pump (32) is arranged at one end of the reaction tank (31), and the water outlet pump (36) is arranged at the other end of the reaction tank (31); in the reaction tank (31), the filter wall (33) and the membrane assembly (35) are arranged in sequence along the flow direction of the wastewater; the membrane assembly (35) includes a plurality of permeable membranes, and the permeable membranes are vertically arranged in the reaction tank (31); The sludge pool (38) is arranged directly below the reaction pool (31), a mounting plate is arranged between the sludge pool (38) and the reaction pool (31), a sinking hole is arranged on the mounting plate, sludge in the sludge pool (38) flows into the sludge pool through the sinking hole, and the sludge pump (37) is arranged at the outlet of the sludge pool (38).

7. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: A plurality of filtering and retaining channels are arranged through the filtering wall (33), each filtering and retaining channel comprising a filtering hole (331) and a retaining hole (332) which are interconnected; the filtering hole (331) is arranged on the water-facing surface, the retaining hole (332) is arranged on the water-receiving surface, and the aperture of the retaining hole (332) is larger than the aperture of the filtering hole (331); The sludge pool (7) is in the shape of a square frustum and is used to hold the sludge intercepted by the filter wall and the sludge washed from the membrane assembly by the membrane cleaning assembly.

8. The high-efficiency biological treatment system for landfill leachate according to claim 1, characterized in that: The membrane cleaning component (34) is used to clean the sludge on the membrane component (35); the membrane cleaning component (34) is arranged above the membrane component (35); The membrane cleaning assembly (34) comprises a plurality of fixed plates (341), a driving assembly (342) and a cleaning brush (343); one or more fixed plates (341) are arranged between two adjacent permeable membranes; the fixed plates (341) and the permeable membranes are arranged in parallel; and a cleaning brush (343) is arranged on both sides of each fixed plate (341); All the fixing plates (341) are connected to the driving assembly (342); the driving assembly (342) is used to drive all the fixing plates (341) to move up and down.

9. A highly efficient biological treatment method for landfill leachate, using the treatment system according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: (1) The landfill leachate enters the primary denitrification treatment equipment for treatment and then enters the nitrification primary denitrification equipment, and the reflux liquid in the nitrification primary denitrification equipment returns to the primary denitrification treatment equipment; Repeat the internal reflux until the chemical oxygen demand (COD) of the landfill leachate treated by the primary nitrification and denitrification treatment subsystem is less than 200 mg / L, the ammonia nitrogen content is less than 20 mg / L, the total nitrogen content is less than 50 mg / L, and it is stable within the requirements within 1 hour. Then stop the internal reflux and the landfill leachate water enters the secondary nitrification and denitrification treatment subsystem; (2) The landfill leachate treated by the primary denitrification treatment equipment enters the secondary denitrification treatment equipment in the secondary nitrification and denitrification treatment subsystem for treatment, and then enters the nitrification deep denitrification equipment. The internal reflux liquid of the nitrification deep denitrification equipment returns to the secondary denitrification treatment equipment; the internal reflux is repeated until the chemical oxygen demand COD of the landfill leachate treated by the secondary nitrification and denitrification treatment subsystem is less than 100 mg / L, the ammonia nitrogen content is less than 10 mg / L, the total nitrogen content is less than 20 mg / L and is stable within the requirements within 1 hour, then the internal reflux is stopped, and the landfill leachate water enters the high-efficiency membrane biological reactor; (3) The high-efficiency membrane bioreactor equipment filters the incoming high-efficiency membrane bioreactor leachate to remove sludge; then it enters the ultrafiltration unit for treatment. The COD removal rate of the effluent water quality of the ultrafiltration unit reaches 93.3%, the ammonia nitrogen removal rate reaches 99.6%, and the total nitrogen removal rate reaches more than 99.3%.

10. The method for efficient biological treatment of landfill leachate according to claim 9, characterized in that: In step (1) and step (2), the nitrification reaction temperature of the digester in the nitrification primary denitrification equipment and the nitrification deep denitrification equipment is controlled at 30-32°C.

Images