Leachate treatment system suitable for sanitary landfill of household garbage

Abstract

The utility model discloses a leachate treatment system suitable for a sanitary landfill of household garbage, which comprises a homogenizing tank, and a pre-aeration system is mounted at the bottom of the homogenizing tank; the homogenizing tank is communicated with an MBR system, and the MBR system comprises a two-stage A / O unit and an MBR membrane unit; the two-stage A / O unit is communicated with a sludge treatment system, and a sludge inlet of the sludge treatment system is communicated with an advanced oxidation coagulating sedimentation unit; the MBR membrane unit is communicated with the NF nanofiltration unit, and water produced by the NF nanofiltration unit is communicated with the RO unit; a concentrated solution of the NF nanofiltration unit is communicated with the advanced oxidation coagulating sedimentation unit, and water produced by the advanced oxidation coagulating sedimentation unit returns to the two-stage A / O unit; a water outlet of the RO unit is connected with the water producing tank, a concentrated solution opening of the RO unit is connected with the RO concentrated water barrel, and the RO unit is connected with the backwashing water pipe. According to the utility model, the treatment process is optimized, the treatment on the concentrated solution is enhanced, the effluent quality is ensured, and the resource utilization of the leachate is promoted.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental engineering, and more specifically relates to a leachate treatment system applicable to domestic waste sanitary landfills. Background Technique

[0002] The leachate of domestic waste sanitary landfills mainly comes from precipitation infiltration, waste water content, and water generated by waste decomposition. The leachate belongs to high-concentration organic wastewater, contains various organic and inorganic harmful components, and has complex water quality.

[0003] Commonly used treatment processes for leachate are: ① MBR + nanofiltration, reverse osmosis; ② anaerobic biological treatment + MBR + nanofiltration, reverse osmosis; ③ pretreatment + DTRO. Process ① is not applicable to leachate with a relatively high ion concentration, and it is difficult to treat the concentrated liquid. Process ② is not applicable to leachate with poor biodegradability. Process ③ has high requirements for the process, and the operation and management costs are relatively high.

[0004] Therefore, there is an urgent need for a leachate treatment system applicable to domestic waste sanitary landfills. Content of the Utility Model

[0005] The technical problem to be solved by the utility model is to provide a leachate treatment system applicable to domestic waste sanitary landfills to solve the problems in the background technique.

[0006] To solve the above technical problems, the technical solutions adopted by the utility model are as follows.

[0007] A leachate treatment system applicable to domestic waste sanitary landfills includes a homogenization tank for mixing fresh leachate and old leachate, and a pre-aeration system is installed at the bottom of the homogenization tank; the homogenization tank is connected to an MBR membrane bioreactor system, and the MBR membrane bioreactor system includes two-stage A / O units located upstream and an MBR membrane unit located downstream, and a reflux pipe for returning liquid to the two-stage A / O units is connected to the MBR membrane unit; the two-stage A / O units are connected to a sludge treatment system, and the inlet of the sludge treatment system is connected to an advanced oxidation coagulation and precipitation unit; the MBR membrane unit is connected to an NF nanofiltration unit for intercepting solutes, and the water produced by the NF nanofiltration unit is connected to an RO reverse osmosis unit; the concentrated liquid of the NF nanofiltration unit is connected to the advanced oxidation coagulation and precipitation unit, and the water produced by the advanced oxidation coagulation and precipitation unit returns to the two-stage A / O units; the outlet of the RO reverse osmosis unit is connected to a water production tank, the concentrated liquid outlet of the RO reverse osmosis unit is connected to an RO concentrated water bucket for re-injection treatment, and an anti-flushing water pipe connected to the MBR membrane unit is connected to the RO reverse osmosis unit.

[0008] Further optimize the technical solution. The MBR membrane bioreactor system consists of three parts: a primary denitrification reactor, a nitrification reactor, a secondary denitrification reactor, a secondary nitrification reactor, and an MBR membrane reactor.

[0009] Further optimize the technical solution. The primary denitrification reactor and the nitrification reactor are two independent operating processes, and all the nitrification reactors are of steel tank structure.

[0010] Further optimize the technical solution. The sludge treatment system includes a sludge tank connected to the sludge outlet of the two-stage A / O unit. The sludge tank is connected to a centrifuge for making sludge cakes; the centrifuge is connected with a sludge supernatant pipe, and the other end of the sludge supernatant pipe is connected to the denitrification reactor of the two-stage A / O unit, and the centrifuge is connected with a dosing unit.

[0011] Further optimize the technical solution. An RO reverse osmosis water supply pump and a booster pump are arranged between the NF nanofiltration unit and the RO reverse osmosis unit.

[0012] Further optimize the technical solution. The outlet of the NF nanofiltration unit is connected with a product water bucket, and the outlet of the product water bucket is connected to the RO reverse osmosis unit; the concentrated liquid outlet of the NF nanofiltration unit is connected with an NF concentrated water bucket, and the outlet of the NF concentrated water bucket is connected to the advanced oxidation coagulation sedimentation unit.

[0013] Further optimize the technical solution. A nanofiltration water supply pump and a booster pump are arranged between the NF nanofiltration unit and the MBR membrane unit.

[0014] Due to the adoption of the above technical solutions, the technical progress achieved by the present utility model is as follows.

[0015] A leachate treatment system applicable to domestic waste sanitary landfills provided by the present utility model combines an advanced oxidation coagulation sedimentation unit with an MBR membrane unit. The supernatant after the treatment of the advanced oxidation coagulation sedimentation unit is refluxed to the nitrification and denitrification reactors, which improves the concentrated liquid treatment capacity and also improves the system's resistance to load shocks. The MBR concentrated water is refluxed to the primary denitrification tank, further reducing the total nitrogen. The present utility model optimizes the treatment process, strengthens the treatment of the concentrated liquid, ensures the water quality of the effluent, and promotes the resource utilization of the leachate. Description of the Drawings

[0016] Figure 1 It is a structural schematic diagram of the present utility model;

[0017] Wherein: 1. Equalization tank, 2. Two-stage A / O unit, 3. MBR membrane unit, 4. NF nanofiltration unit, 41. Product water tank, 42. NF concentrated water tank, 5. RO reverse osmosis unit, 51. RO concentrated water tank, 6. Product water pool, 7. Advanced oxidation coagulation and sedimentation unit, 8. Sludge treatment system, 81. Sludge tank, 82. Centrifugal dehydrator, 9. Chemical dosing unit, 10. Return pipe, 11. Backwash water pipe, 13. Sludge supernatant pipe. Detailed implementation mode

[0018] The present utility model will be further described in detail below in conjunction with the drawings and specific embodiments.

[0019] A leachate treatment system applicable to domestic waste sanitary landfills, combined with Figure 1 As shown, it includes an equalization tank 1, an MBR membrane bioreactor system, an NF nanofiltration unit 4, a product water tank 41, an NF concentrated water tank 42, an RO reverse osmosis unit 5, an RO concentrated water tank 51, a product water pool 6, an advanced oxidation coagulation and sedimentation unit 7, a sludge treatment system 8, a return pipe 10, a backwash water pipe 11, and a low-hardness liquid pipe 12. The MBR membrane bioreactor system includes a two-stage A / O unit 2 and an MBR membrane unit 3; the sludge treatment system 8 includes a sludge tank, a centrifugal dehydrator, a chemical dosing unit 9, and a sludge supernatant pipe 13.

[0020] A pre-aeration system is installed at the bottom of the equalization tank 1. The equalization tank 1 is used to mix fresh leachate and old leachate in a certain proportion to achieve a biodegradable carbon-nitrogen ratio.

[0021] The equalization tank 1 is connected to the MBR membrane bioreactor system. The MBR membrane bioreactor system includes a two-stage A / O unit 2 located upstream and an MBR membrane unit 3 located downstream, and the MBR membrane unit 3 is connected to a return pipe 10 for returning liquid to the two-stage A / O unit 2. The MBR membrane bioreactor system consists of a first-stage denitrification reactor, a nitrification reactor, a second-stage denitrification reactor, a second-stage nitrification reactor, and an MBR membrane reactor. The first-stage denitrification reactor and the nitrification reactor are two independent operating processes, and all the nitrification reactors are made of steel tank structures.

[0022] The two-stage A / O unit 2 is connected to the sludge treatment system 8. The sludge treatment system 8 includes a sludge tank connected to the sludge outlet of the two-stage A / O unit 2. The sludge tank is connected to a centrifugal dehydrator for making sludge cakes. The water content of the dehydrated sludge cakes is 60%. The sludge cakes are transported out or landfilled. The clear liquid outlet of the centrifugal dehydrator is connected to a sludge supernatant pipe 13. The other end of the sludge supernatant pipe 13 is connected to the denitrification reactor of the two-stage A / O unit 2, and the centrifugal dehydrator is connected to a chemical dosing unit 9.

[0023] The sludge inlet of the sludge treatment system 8 is connected to the advanced oxidation coagulation sedimentation unit 7, and the advanced oxidation adopts the Fenton oxidation process. The water produced by the advanced oxidation coagulation sedimentation unit 7 returns to the two-stage A / O unit 2 after hardness removal, and the produced sludge is discharged into the sludge pool.

[0024] The MBR membrane unit 3 is connected to the NF nanofiltration unit 4 for intercepting solutes. A nanofiltration water supply pump and a booster pump are arranged between the NF nanofiltration unit 4 and the MBR membrane unit 3. The interception of solutes by the NF nanofiltration unit 4 reduces various pollution indexes to meet the discharge standards. The water outlet of the NF nanofiltration unit 4 is connected to a water production bucket 41, and the water outlet of the water production bucket 41 is connected to the RO reverse osmosis unit 5; the concentrated liquid outlet of the NF nanofiltration unit 4 is connected to an NF concentrated water bucket 42, and the water outlet of the NF concentrated water bucket 42 is connected to the advanced oxidation coagulation sedimentation unit 7.

[0025] The water produced by the NF nanofiltration unit 4 is connected to the RO reverse osmosis unit 5. A reverse osmosis water supply pump and a booster pump are arranged between the NF nanofiltration unit 4 and the RO reverse osmosis unit 5. The water outlet of the RO reverse osmosis unit 5 is connected to a water production pool 6, the concentrated liquid port of the RO reverse osmosis unit 5 is connected to an RO concentrated water bucket 51 for re-injection treatment, and the RO reverse osmosis unit 5 is connected to a backwash water pipe 11 communicating with the MBR membrane unit 3.

[0026] When the utility model is actually used, the homogenization tank 1 is built into a reinforced concrete structure with all-underground construction, and the effective volume is 300 - 400 m 3 , and a pre-aeration system, a water inlet pump, a bag filter, etc. are configured. There are two first-stage denitrification reactors in the MBR membrane bioreactor system, with an effective volume of 700 m 3 , four first-stage nitrification reactors, with an effective volume of 1000 m 3 . The reactor material is a carbon steel tank, the design temperature is 25 °C, the design sludge concentration is 15 g / l, the design maximum reflux is 18.2, and the design nitrification sludge age is 18 d. There is one second-stage denitrification reactor and one second-stage nitrification reactor, with an effective volume of 500 m 3 , the reactor material is a carbon steel tank, and the design temperature is 25 °C, and the design sludge concentration is 15 g / l. The treatment scale of the MBR membrane unit 3 is set to 800 m 3 / d, the membrane filtration flux is 67 l / (m 2 ·h), and the total membrane area is 467.5 m 2 . The treatment scale of the NF nanofiltration unit 4 is set to 800 m 3 / d, the water production rate is 85%, and the total membrane area is 1600 m 2 . The RO reverse osmosis unit is designed with a reverse osmosis treatment scale of 400 m 3 / d, the water production rate is 75%, and the total membrane area is 1100 m 2 . The advanced oxidation coagulation sedimentation unit 7 is provided with one oxidation tank and two coagulation sedimentation tanks, with an effective volume of 500 m3 。In the sludge treatment system 8, the sludge pool has an effective volume of 40 m 3 , and is equipped with a centrifugal pump.

[0027] The treatment scale of the leachate treatment project of the present utility model is 250 - 400 m 3 / d. The water quality index of the effluent after leachate treatment should meet the discharge limit requirements in Table 2 of the "Pollution Control Standard for Domestic Waste Landfills" (GB16889 - 2008). As shown in the following table.

[0028] Leachate effluent water quality standard (mg / l)

[0029] Project COD <![CDATA[BOD5]]> SS Ammonia nitrogen TN Index ≤100 ≤30 ≤30 ≤25 ≤40

Claims

1. A leachate treatment system applicable to domestic waste sanitary landfills, characterized in that: It includes a homogenization tank (1) for mixing fresh leachate and old leachate, and a pre-aeration system is installed at the bottom of the homogenization tank (1); the homogenization tank (1) is connected to an MBR membrane bioreactor system, and the MBR membrane bioreactor system includes two-stage A / O units (2) located upstream and an MBR membrane unit (3) located downstream, and a reflux pipe (10) for returning liquid to the two-stage A / O units (2) is connected to the MBR membrane unit (3); the two-stage A / O units (2) are connected to a sludge treatment system (8), and an advanced oxidation coagulation and sedimentation unit (7) is connected to the sludge inlet of the sludge treatment system (8); the MBR membrane unit (3) is connected to an NF nanofiltration unit (4) for intercepting solutes, and the water produced by the NF nanofiltration unit (4) is connected to an RO reverse osmosis unit (5); the concentrated liquid of the NF nanofiltration unit (4) is connected to the advanced oxidation coagulation and sedimentation unit (7), and the water produced by the advanced oxidation coagulation and sedimentation unit (7) returns to the two-stage A / O units (2); the water outlet of the RO reverse osmosis unit (5) is connected to a product water tank (6), the concentrated liquid outlet of the RO reverse osmosis unit (5) is connected to an RO concentrated water bucket (51) for re-injection treatment, and an anti-flushing water pipe (11) connected to the MBR membrane unit (3) is connected to the RO reverse osmosis unit (5).

2. The leachate treatment system applicable to domestic waste sanitary landfill according to claim 1, wherein: The MBR membrane bioreactor system consists of three parts: a primary denitrification reactor, a nitrification reactor, a secondary denitrification reactor, a secondary nitrification reactor and an MBR membrane reactor.

3. The leachate treatment system applicable to domestic waste sanitary landfill according to claim 2, wherein: The primary denitrification reactor and the nitrification reactor are two independent operating processes, and all the nitrification reactors are of steel tank structure.

4. The leachate treatment system applicable to domestic waste sanitary landfill according to claim 1, wherein: The sludge treatment system (8) includes a sludge tank connected to the sludge outlet of the two-stage A / O units (2), and the sludge tank is connected to a centrifuge for making sludge cakes; the centrifuge is connected to a sludge clear liquid pipe (13), the other end of the sludge clear liquid pipe (13) is connected to the denitrification reactor of the two-stage A / O units (2), and the centrifuge is connected to a dosing unit (9).

5. The leachate treatment system applicable to domestic waste sanitary landfill site according to claim 1, characterized in that: An RO feed water pump and a booster pump are arranged between the NF nanofiltration unit (4) and the RO reverse osmosis unit (5).

6. The leachate treatment system applicable to domestic waste sanitary landfill according to claim 5, characterized in that: The water outlet of the NF nanofiltration unit (4) is connected to a product water bucket (41), and the water outlet of the product water bucket (41) is connected to the RO reverse osmosis unit (5); the concentrated liquid outlet of the NF nanofiltration unit (4) is connected to an NF concentrated water bucket (42), and the water outlet of the NF concentrated water bucket (42) is connected to the advanced oxidation coagulation and sedimentation unit (7).

7. The leachate treatment system applicable to domestic waste sanitary landfill according to claim 1, characterized in that: An NF feed water pump and a booster pump are arranged between the NF nanofiltration unit (4) and the MBR membrane unit (3).

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