Landfill leachate treatment system

Abstract

The utility model discloses a landfill leachate treatment system which comprises an adjusting tank, a homogenizing tank, a PH (potential of hydrogen) adjusting tank, a reduction tank, a neutralization tank, a reaction tank, a coagulation tank, a flocculation tank, an inclined tube sedimentation tank, an intermediate tank, a quartz sand filter, a hydrolysis acidification tank, an MBR (membrane bioreactor) membrane tank, an activated carbon filter, an RO (reverse osmosis) unit and a clear water tank which are sequentially connected along the water flow direction, the reduction tank is connected with a reducing agent dosing barrel, the neutralization tank is connected with an alkali liquor dosing barrel, the reaction tank is connected with a heavy supplement agent dosing barrel, the coagulation tank is connected with a PAC dosing barrel, the flocculation tank is connected with a PAM dosing barrel, the MBR membrane pool is connected with a first cleaning pipeline, the front side of the RO unit is connected with a scale inhibitor dosing pipeline, and the RO unit is further connected with a second cleaning pipeline. According to the landfill leachate treatment system disclosed by the utility model, efficient treatment of leachate, stable up-to-standard discharge and long-period stable operation of a membrane system are realized by optimizing pretreatment, strengthening membrane cleaning and scale inhibition control.

Description

Technical Field

[0001] This utility model relates to the field of waste treatment technology, and in particular to a landfill leachate treatment system. Background Technology

[0002] Landfill leachate is a high-concentration organic wastewater produced during the landfill process due to anaerobic fermentation, organic matter decomposition, and rainwater runoff. Its composition is complex, and its water quality and quantity vary greatly over time. It is a major source of pollution for landfills, and if it is not properly treated and discharged directly, it will cause serious secondary damage to the environment.

[0003] With the rise of the membrane industry, ultrafiltration, nanofiltration, and reverse osmosis membranes have been widely used in water treatment, especially in the fields of pure water and reclaimed water. However, due to the strict requirements of pretreatment processes, membrane methods have not been very effective in leachate wastewater treatment. Utility Model Content

[0004] The purpose of this invention is to provide a landfill leachate treatment system to solve the problems existing in the prior art.

[0005] The purpose of this utility model is achieved as follows: A landfill leachate treatment system includes, in sequence along the water flow direction, an equalization tank, a homogenization tank, a pH equalization tank, a reduction tank, a neutralization tank, a reaction tank, a coagulation tank, a flocculation tank, an inclined tube sedimentation tank, an intermediate tank, a quartz sand filter, a hydrolysis acidification tank, an MBR membrane tank, an activated carbon filter, an RO unit, and a clear water tank. The pH equalization tank is connected to an acid dosing tank, the reduction tank is connected to a reducing agent dosing tank, the neutralization tank is connected to an alkali dosing tank, the reaction tank is connected to a replenishing agent dosing tank, the coagulation tank is connected to a PAC dosing tank, the flocculation tank is connected to a PAM dosing tank, the MBR membrane tank is connected to a first cleaning pipeline, the RO unit is connected to a scale inhibitor dosing pipeline, and the RO unit is also connected to a second cleaning pipeline.

[0006] This utility model's landfill leachate treatment system utilizes multi-stage pretreatment units (pH adjustment, reduction, neutralization, coagulation, flocculation, sedimentation, etc.) to synergistically remove heavy metals and colloids. A hydrolysis acidification tank further decomposes complex organic matter into smaller molecules, improving the wastewater's biodegradability and creating favorable conditions for subsequent MBR and RO processes. Furthermore, the inclusion of a first cleaning pipeline, a second cleaning pipeline, and an antiscalant dosing pipeline significantly extends membrane life and reduces operating costs. In summary, this utility model's landfill leachate treatment system, through optimized pretreatment, enhanced membrane cleaning, and scale inhibition control, achieves efficient leachate treatment, stable discharge meeting standards, and long-term stable operation of the membrane system.

[0007] As a further improvement of this utility model, the RO unit includes a primary RO membrane module and a secondary RO membrane module. A high-pressure pump and a first security filter are installed upstream of the inlet of the primary RO membrane module. The first security filter removes residual suspended solids (SS < 1 mg / L), colloids, and particulate matter from the leachate, preventing membrane module clogging. An antiscalant dosing line is connected upstream of the security filter. The concentrate outlet of the primary RO membrane module is connected to the inlet of the secondary RO membrane module, and the concentrate outlet of the secondary RO membrane module is connected to a concentrate tank. The outlets of both the primary and secondary RO membrane modules are connected to a clean water tank. Through two-stage RO treatment, the system recovery rate is significantly improved (80%~85%), while the concentrate volume is reduced by 40%.

[0008] As a further improvement of this utility model, the second cleaning pipeline is connected to the chemical cleaning tank, and a chemical cleaning pump and a second security filter are provided at the front of the chemical cleaning tank. The second security filter intercepts particulate contaminants in the cleaning solution, such as undissolved crystals or impurities that may be contained in the cleaning agent itself, and dirt that falls off the membrane surface during the cleaning process. This protects the RO membrane module, prevents particles from getting stuck in the membrane gaps, affecting the uniform distribution of the cleaning solution, and prevents hard particles (such as CaCO3 fragments) from rubbing against the membrane surface and causing scratches. At the same time, it improves the cleaning efficiency, allowing the clean cleaning solution to fully contact the contaminants on the membrane surface and preventing impurities from "shielding" the reaction interface between the chemical agent and the dirt.

[0009] As a further improvement of this utility model, a buffer tank is provided on the first cleaning pipeline. An alkaline washing pipeline and an acid washing pipeline are connected in parallel to the buffer tank. The alkaline washing pipeline is connected to a sodium hypochlorite dosing tank via a suction pump, and the acid washing pipeline is connected to a hydrochloric acid dosing point. Both the alkaline washing and acid washing pipelines are equipped with control valves. By periodically alternating between alkaline and acid washing, the MBR membrane flux recovery rate is increased by more than 30%.

[0010] As a further improvement of this utility model, the clean water tank is connected to a flushing pipeline and a backwashing pipeline. The flushing pipeline is connected to the front side of the RO unit through a flushing pump, and the backwashing pipeline is connected to the front side of the buffer tank through a backwashing pump. Through regular backwashing, the membrane life is further improved. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the landfill leachate treatment system of this utility model.

[0012] The system includes: 1. Equalization tank; 2. Homogenization tank; 3. pH adjustment tank; 4. Reduction tank; 5. Neutralization tank; 6. Reaction tank; 7. Coagulation tank; 8. Flocculation tank; 9. Inclined tube sedimentation tank; 10. Intermediate tank; 11. Quartz sand filter; 12. Hydrolysis acidification tank; 13. MBR membrane tank; 14. Activated carbon filter; 15. Primary RO membrane module; 16. Secondary RO membrane module; 17. Clear water tank; 18. Concentrate tank; 19. First security filter; 20. Acid dosing tank; 21. Reducing agent dosing tank; 22. Alkali dosing tank; 23. Replenishing agent dosing tank; 24. PAC dosing tank; 25. PAM dosing tank; 26. Buffer tank; 27. Sodium hypochlorite dosing tank; 28. Hydrochloric acid dosing point; 29. ​​Scale inhibitor dosing tank; 30. Chemical cleaning tank; 31. Second security filter; 32. Flushing pump; 33. Backwash pump; 34. Sludge tank; 35. Filter press. Detailed Implementation

[0013] like Figure 1 The landfill leachate treatment system shown includes, in sequence along the water flow direction, an equalization tank 1, a homogenization tank 2, a pH equalization tank 3, a reduction tank 4, a neutralization tank 5, a reaction tank 6, a coagulation tank 7, a flocculation tank 8, an inclined tube sedimentation tank 9, an intermediate tank 10, a quartz sand filter 11, a hydrolysis acidification tank 12, an MBR membrane tank 13, an activated carbon filter 14, an RO unit, and a clear water tank 17.

[0014] The RO unit consists of a primary RO membrane module 15 and a secondary RO membrane module 16. A high-pressure pump and a first security filter 19 are installed upstream of the inlet of the primary RO membrane module 15. The first security filter 19 removes residual suspended solids (SS < 1 mg / L), colloids, and particulate matter from the leachate, preventing membrane module clogging. An antiscalant dosing line is connected upstream of the security filter. The concentrate outlet of the primary RO membrane module 15 is connected to the inlet of the secondary RO membrane module 16, and the concentrate outlet of the secondary RO membrane module 16 is connected to a concentrate tank 18. The outlets of both the primary and secondary RO membrane modules 15 are connected to a clear water tank 17. Through two-stage RO treatment, the system recovery rate is significantly improved (80%~85%), while the concentrate volume is reduced by 40%.

[0015] pH adjustment tank 3 is connected to acid dosing tank 20, reduction tank 4 is connected to reducing agent dosing tank 21, neutralization tank 5 is connected to alkali dosing tank 22, reaction tank 6 is connected to heavy additive dosing tank 23, coagulation tank 7 is connected to PAC dosing tank 24, and flocculation tank 8 is connected to PAM dosing tank 25. Thus, pH adjustment tank 3 adjusts the pH of the leachate to 3.0-4.0, providing a suitable acidic environment for subsequent heavy metal reduction reactions; reduction tank 4 reduces high-valence heavy metals to low-valence states, facilitating subsequent neutralization and precipitation; neutralization tank 5 adjusts the pH to 8.5-9.5, promoting the formation of hydroxide precipitates from the reduced heavy metal ions; reaction tank 6 deeply removes dissolved heavy metal ions, forming stable chelate precipitates; coagulation tank 7 destabilizes and aggregates fine suspended matter and colloidal particles into small flocs; and flocculation tank 8 coagulates the micro-flocs formed by coagulation into large flocs, accelerating sedimentation. Thus, through multi-stage pretreatment, heavy metals are removed in stages with a total removal rate of >99%, avoiding heavy metal poisoning of MBR microorganisms or fouling of RO membranes; at the same time, colloids are destabilized in stages with a colloid removal rate of >90%, significantly reducing the risk of membrane fouling.

[0016] The MBR membrane tank 13 is connected to a first cleaning pipeline. A buffer tank 26 is installed on the first cleaning pipeline, with an alkaline washing pipeline and an acid washing pipeline connected in parallel to the buffer tank 26. The alkaline washing pipeline is connected to a sodium hypochlorite dosing tank 27 via a suction pump, and the acid washing pipeline is connected to a hydrochloric acid dosing point 28. Both the alkaline and acid washing pipelines are equipped with control valves. By periodically alternating between alkaline and acid washing, the MBR membrane flux recovery rate is increased by more than 30%.

[0017] The RO unit is connected to an antiscalant dosing line at the front, which is connected to the antiscalant dosing tank 29. The RO unit is also connected to a second cleaning line. This second cleaning line connects to a chemical cleaning tank 30, which has a chemical cleaning pump and a second security filter 31 at the front. The second security filter 31 intercepts particulate contaminants in the cleaning solution, such as undissolved crystals or impurities that may be present in the cleaning agent itself, and dirt that detaches from the membrane surface during cleaning. This protects the RO membrane assembly, prevents particles from getting stuck in the membrane gaps, affecting the uniform distribution of the cleaning solution, and prevents hard particles (such as CaCO3 fragments) from rubbing against the membrane surface and causing scratches. It also improves cleaning efficiency, allowing the clean cleaning solution to fully contact the contaminants on the membrane surface, preventing impurities from "shielding" the reaction interface between the chemical agents and the dirt.

[0018] The clean water tank 17 is connected to a flushing pipeline and a backwashing pipeline. The flushing pipeline is connected to the front of the RO unit via the flushing pump 32, and the backwashing pipeline is connected to the front of the buffer tank 26 via the backwashing pump 33. Regular backwashing further improves the membrane life.

[0019] The bottom of the inclined tube sedimentation tank 9 is connected to a sludge discharge pipe, which is connected to the filter press 35 via a pump. A sludge tank 34 is installed on the sludge discharge pipe, and the pump is located on both the front and rear sides of the sludge tank 34. The sludge from the sedimentation tank is discharged into the filter press 35, where solid-liquid separation is achieved, facilitating subsequent treatment.

[0020] The landfill leachate treatment system in this embodiment achieves efficient leachate treatment, stable discharge meeting standards, and long-term stable operation of the membrane system by optimizing pretreatment, enhancing membrane cleaning, and controlling scale inhibition.

[0021] This utility model is not limited to the above embodiments. Based on the technical solutions disclosed in this utility model, those skilled in the art can make some substitutions and modifications to some of the technical features without creative labor, and these substitutions and modifications are all within the protection scope of this utility model.

Claims

1. A landfill leachate treatment system, characterized in that: The system includes, in sequence along the water flow direction, an equalization tank, a homogenization tank, a pH equalization tank, a reduction tank, a neutralization tank, a reaction tank, a coagulation tank, a flocculation tank, an inclined tube sedimentation tank, an intermediate tank, a quartz sand filter, a hydrolysis acidification tank, an MBR membrane tank, an activated carbon filter, an RO unit, and a clear water tank. The pH equalization tank is connected to an acid dosing tank, the reduction tank is connected to a reducing agent dosing tank, the neutralization tank is connected to an alkali dosing tank, the reaction tank is connected to a supplementary agent dosing tank, the coagulation tank is connected to a PAC dosing tank, the flocculation tank is connected to a PAM dosing tank, the MBR membrane tank is connected to a first cleaning pipeline, the RO unit is connected to an antiscalant dosing pipeline, and the RO unit is also connected to a second cleaning pipeline.

2. The landfill leachate treatment system according to claim 1, characterized in that: The RO unit includes a primary RO membrane module and a secondary RO membrane module. A high-pressure pump and a first security filter are installed on the front side of the inlet of the primary RO membrane module. The scale inhibitor dosing pipeline is connected to the front side of the security filter. The concentrate outlet of the primary RO membrane module is connected to the inlet of the secondary RO membrane module. The concentrate outlet of the secondary RO membrane module is connected to the concentrate tank. The outlets of both the primary and secondary RO membrane modules are connected to the clear water tank.

3. The landfill leachate treatment system according to claim 2, characterized in that: The second cleaning pipeline is connected to a chemical cleaning tank, which is equipped with a chemical cleaning pump and a second security filter at the front.

4. The landfill leachate treatment system according to claim 1, characterized in that: The first cleaning pipeline is equipped with a buffer tank, and the buffer tank is connected in parallel with an alkaline washing pipeline and an acid washing pipeline. The alkaline washing pipeline is connected to a sodium hypochlorite dosing tank via a suction pump, and the acid washing pipeline is connected to a hydrochloric acid dosing point. Both the alkaline washing pipeline and the acid washing pipeline are equipped with control valves.

5. The landfill leachate treatment system according to claim 4, characterized in that: The clean water tank is connected to a flushing pipeline and a backwashing pipeline. The flushing pipeline is connected to the front of the RO unit via a flushing pump, and the backwashing pipeline is connected to the front of the buffer medicine tank via a backwashing pump.

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