High-efficiency and low-cost treatment system for leachate of refuse landfill

Abstract

The invention discloses a high-efficiency low-cost treatment system for refuse landfill leachate, which adopts an anaerobic + MBR + nanofiltration treatment process, and comprises a filtrate regulating tank, a self-cleaning filter, a UASB reactor, a denitrification tank, a nitrification tank, an MBR membrane tank, a nanofiltration tank and a clean water tank which are communicated in sequence, and the nanofiltration tank is communicated with a concentrated solution storage tank; the UASB reactor and the MBR membrane tank are simultaneously communicated with a sludge concentration tank, and the sludge concentration tank is provided with a dehydrator; and a mixed liquid backflow system is arranged between the nitrification tank and the denitrification tank. The technical scheme can adapt to the fluctuation of the percolate concentration in different seasons and different years, and has the advantages of simple process flow, small occupied area, low operation and maintenance cost, high automatic control degree and the like, and the treated percolate can reach the emission standard of environmental protection requirements.

Description

Technical Field

[0001] The invention relates to the technical field of landfill leachate treatment, in particular to a landfill leachate treatment system with high efficiency and low cost. Background Art

[0002] Landfill leachate is a high-concentration wastewater produced in urban landfills. It has complex pollutants, high salt content, high ammonia nitrogen concentration, high organic matter concentration, and poor biodegradability. It is difficult to treat it to meet the standards using a single treatment process. The commonly used treatment system that combines multiple processes often has disadvantages such as high operating costs and secondary pollution.

[0003] Therefore, in view of the difficulties in leachate treatment, it is necessary to design an efficient and low-cost landfill leachate treatment system to solve the above problems. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a landfill leachate treatment system that can purify leachate with high efficiency and low operating cost, ensure that the pollution of the environment by the landfill leachate is reduced to a minimum, and can achieve stable operation.

[0005] To achieve the above purpose, the technical solution provided by the present invention is: a landfill leachate treatment system with high efficiency and low cost, which adopts a treatment process combining anaerobic reaction of UASB reactor + ultrafiltration membrane of MBR membrane pool + nanofiltration membrane of nanofiltration pool, and comprises the following steps: 1) The leachate enters the filtrate regulating tank, and reagents are added to the regulating tank to adjust the pH value of the leachate; 2) The leachate regulated in the regulating tank enters the self-cleaning filter through a floating pump to remove some suspended SS in the wastewater; 3) The leachate after treatment by the self-cleaning filter enters the UASB reactor to remove most of the organic matter and SS in the leachate; 4) The leachate treated by the UASB reactor enters the denitrification tank and nitrification tank in turn. Part of the mixed liquid from the nitrification tank flows back to the denitrification tank for biological denitrification to further degrade the organic matter in the leachate. ) The leachate treated by the denitrification tank and nitrification tank enters the MBR membrane tank, and the ultrafiltration membrane is used to intercept microorganisms and sludge impurities in the reactor; 6) The leachate after filtration in the MBR membrane pool enters the nanofiltration pool, where the nanofiltration membrane is used to remove organic matter that is difficult to biodegrade; 7) The leachate filtered through the nanofiltration tank enters the clean water tank and is discharged after being tested and meeting the standards; 8) The sludge produced by the UASB reactor in step 3) and the MBR membrane tank in step 5) enters the sludge thickening tank and the dehydrator in turn for dehydration treatment. After the sludge is treated, it is transported out in a centralized manner, and the supernatant and the filtrate in the thickening tank are returned to the self-cleaning filter in step 2); 9) The concentrated liquid produced by the nanofiltration tank in step 6) enters the concentrated liquid storage tank and is regularly refilled into the landfill or transported out for incineration.

[0006] In step 1), the reagents are dilute sulfuric acid and NaOH solution, and the pH value of the filtrate is adjusted to between 6.5 and 7.5; preferably, the pH value is adjusted to 7.0.

[0007] In step 2), the floating pump is a Chuanyuan CP3-65 stainless steel submersible pump with a designed maximum lifting flow of 25.2m 3 / h, the minimum head is 18m and the power is 3.7kW.

[0008] In step 3), in the UASB reactor, the pH value is 7.0, the hydraulic retention time is 24 h, and the operating temperature is 35 ± 3 °C.

[0009] In step 4), the residence time ratio of the denitrification tank to the nitrification tank is 1:3, and the mixed liquor reflux ratio is 400%.

[0010] In step 5), the flux F of the ultrafiltration membrane is 1.56 m 3 / (m 2 ·d), the membrane pore size is 30 nm, and the maximum membrane flux is 3.6m 3 / (m 2 ·d).

[0011] In step 6), the recovery rate of the nanofiltration membrane was 80%.

[0012] In step 7), if the test fails to meet the standard, return to step 1) and repeat the process.

[0013] In step 8), the regular sludge discharge interval in the sludge thickening tank is 8 hours.

[0014] The present invention adopts the above technical solution, which has the following beneficial effects: 1. Since the COD value of the leachate is very high, the anaerobic process UASB reactor is used to degrade most of the organic matter. It has low energy consumption, does not require aeration, reduces power consumption, and saves energy. The anaerobic reaction can produce biogas, which can be used as energy. In addition, the pH value of the leachate is close to the suitable pH of the UASB reactor, which avoids or reduces pH adjustment, saves costs, and avoids the high energy consumption caused by the direct use of MBR.

[0015] 2. MBR is a highly efficient wastewater treatment process that combines biochemical reactors and membrane separation, and membrane separation replaces the secondary sedimentation tank of conventional biochemical processes. Compared with the traditional activated sludge process, MBR has a much higher removal rate for organic matter. In the membrane bioreactor, due to the greatly improved separation efficiency, the concentration of microorganisms in the biochemical reactor can be increased from 3 to 6 g / L in the conventional method to 15 to 20 g / L, and a better removal effect can be achieved in a shorter hydraulic retention time than the traditional activated sludge method, reducing the volume of the biochemical reactor, improving the efficiency of the biochemical reaction, and the effluent is free of bacteria and suspended solids, which has great advantages in improving the system processing capacity and improving the effluent water quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a schematic flow diagram of a system for efficiently and cost-effectively treating landfill leachate. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below in conjunction with the implementation modes and the accompanying drawings.

[0018] like Figure 1 As shown, a landfill leachate high-efficiency and low-cost treatment system adopts a treatment process combining the anaerobic reaction of the UASB reactor + the ultrafiltration membrane of the MBR membrane pool + the nanofiltration membrane of the nanofiltration pool. The system includes a filtrate regulating tank, a self-cleaning filter, a UASB reactor, a denitrification tank, a nitrification tank, an MBR membrane pool, a nanofiltration tank and a clear water tank which are connected in sequence. The nanofiltration tank is also connected to a concentrated liquid storage tank; the sludge outlets of the UASB reactor and the MBR membrane pool are simultaneously connected to the sludge thickening tank, and the sludge thickening tank is equipped with a dehydrator; a mixed liquid reflux system is arranged between the nitrification tank and the denitrification tank.

[0019] 1. The leachate enters the filtrate regulating tank, and dilute sulfuric acid and NaOH solution are added to the regulating tank to adjust the pH value of the leachate.

[0020] Preferably, the pH value of the leachate is adjusted to between 6.5 and 7.5. More preferably, the pH value of the leachate is adjusted to 4.0.

[0021] 2. The leachate regulated in the regulating tank enters the self-cleaning filter through the Chuanyuan CP3-65 stainless steel submersible pump to remove part of the suspended SS in the wastewater and reduce the load of the subsequent UASB reactor treatment.

[0022] Preferably, the maximum designed lifting flow is 25.2m 3 / h, the minimum head is 18m and the power is 3.7kW.

[0023] 3. The leachate treated by the self-cleaning filter enters the UASB reactor to remove most of the organic matter and SS in the leachate and improve the biodegradability of the leachate.

[0024] Preferably, the pH value is 7.0, the hydraulic retention time is 24 hours, and the operating temperature is 35°C.

[0025] 4. The leachate treated by the UASB reactor enters the denitrification tank and nitrification tank in turn. Part of the mixed liquid in the nitrification tank flows back to the denitrification tank for biological denitrification to further degrade the organic matter in the leachate. Preferably, the residence time ratio of the denitrification tank to the nitrification tank is 1:3, and the mixed liquor reflux ratio is 400%.

[0026] 5. The leachate treated by the denitrification tank and nitrification tank enters the MBR membrane tank, and the ultrafiltration membrane is used to intercept microorganisms and sludge impurities in the reactor; Preferably, the flux of the ultrafiltration membrane is 1.56 m 3 / (m 2 ·d), the membrane pore size is 30 nm, and the maximum membrane flux is 3.6 m 3 / (m 2 ·d).

[0027] 6. The leachate after filtration in the MBR membrane pool enters the nanofiltration pool, and the nanofiltration membrane is used to remove organic matter that is difficult to biodegrade, such as humic acid, benzene and other substances; Preferably, the nanofiltration membrane recovery rate is 80%.

[0028] 7. The leachate filtered by the nanofiltration tank enters the clean water tank and is discharged after the test meets the standard. If the test does not meet the standard, return to step 1 and repeat the process.

[0029] 8. The sludge produced by the UASB reactor and the MBR membrane tank enters the sludge thickening tank and the dehydrator in turn for dehydration treatment. After the sludge is treated, it is transported out in a centralized manner, and the supernatant and filtrate in the thickening tank are returned to the sewage treatment system; Preferably, the regular sludge discharge interval of the sludge thickening tank is 8 hours.

[0030] 9. The concentrated liquid produced by the nanofiltration tank enters the concentrated liquid storage tank and is regularly re-injected into the landfill or transported out for incineration.

[0031] The above implementation modes are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with this technology to understand the content of the present invention and implement it, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A landfill leachate high-efficiency and low-cost treatment system, characterized in that: The treatment process using the anaerobic reaction of the UASB reactor + the ultrafiltration membrane of the MBR membrane pool + the nanofiltration membrane of the nanofiltration pool includes the following steps: 1) The leachate enters the filtrate regulating tank, and reagents are added to the regulating tank to adjust the pH value of the leachate; 2) The leachate regulated in the regulating tank enters the self-cleaning filter through a floating pump to remove some suspended SS in the wastewater; 3) The leachate after treatment by the self-cleaning filter enters the UASB reactor to remove most of the organic matter and SS in the leachate; 4) The leachate treated by the UASB reactor enters the denitrification tank and nitrification tank in turn. Part of the mixed liquid from the nitrification tank flows back to the denitrification tank for biological denitrification to further degrade the organic matter in the leachate. 5) The leachate treated in the denitrification tank and nitrification tank enters the MBR membrane tank, and the ultrafiltration membrane is used to intercept microorganisms and sludge impurities in the reactor; 6) The leachate after filtration in the MBR membrane pool enters the nanofiltration pool, where the nanofiltration membrane is used to remove organic matter that is difficult to biodegrade; 7) The leachate filtered through the nanofiltration tank enters the clean water tank and is discharged after being tested and meeting the standards; 8) The sludge produced by the UASB reactor in step 3) and the MBR membrane tank in step 5) enters the sludge thickening tank and the dehydrator in turn for dehydration treatment. After the sludge is treated, it is transported out in a centralized manner, and the supernatant and the filtrate in the thickening tank are returned to the self-cleaning filter in step 2); 9) The concentrated liquid produced by the nanofiltration tank in step 6) enters the concentrated liquid storage tank and is regularly refilled into the landfill or transported out for incineration.

2. A landfill leachate high-efficiency and low-cost treatment system according to claim 1, characterized in that: In step 1), the reagents are dilute sulfuric acid and NaOH solution, and the pH value of the filtrate is adjusted to between 6.5 and 7.5; preferably, the pH value is adjusted to 7.

0.

3. The landfill leachate high-efficiency and low-cost treatment system according to claim 1 is characterized in that: In step 2), the floating pump is a Chuanyuan CP3-65 stainless steel submersible pump with a designed maximum lifting flow of 25.2m 3 / h, the minimum head is 18m and the power is 3.7kW.

4. The landfill leachate high-efficiency and low-cost treatment system according to claim 1 is characterized in that: In step 3), in the UASB reactor, the pH value is 7.0, the hydraulic retention time is 24 h, and the operating temperature is 35 ± 3 °C.

5. The landfill leachate high-efficiency and low-cost treatment system according to claim 1 is characterized in that: In step 4), the residence time ratio of the denitrification tank to the nitrification tank is 1:3, and the mixed liquor reflux ratio is 400%.

6. The landfill leachate high-efficiency and low-cost treatment system according to claim 1, characterized in that: In step 5), the flux F of the ultrafiltration membrane is 1.56 m 3 / (m 2 ·d), the membrane pore size is 30 nm, and the maximum membrane flux is 3.6 m 3 / (m 2 ·d).

7. The landfill leachate high-efficiency and low-cost treatment system according to claim 1, characterized in that: In step 6), the recovery rate of the nanofiltration membrane was 80%.

8. The landfill leachate high-efficiency and low-cost treatment system according to claim 1, characterized in that: In step 7), if the test fails to meet the standard, return to step 1) and repeat the process.

9. The landfill leachate high-efficiency and low-cost treatment system according to claim 1, characterized in that: In step 8), the regular sludge discharge interval in the sludge thickening tank is 8 hours.

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