The treatment of landfill leachate has always been a difficult problem in the design, operation and management of landfill. Leachate is the product of liquid gravity flow in landfill, which mainly comes from precipitation and water contained in garbage itself. Because there are many factors that may affect the properties of leachate in the process of liquid flow, including physical factors, chemical factors and biological factors, the properties of leachate change in a considerable range. Generally speaking, its pH value is 4-9, COD is 2,000-62,000 mg/L, BOD5 is 60-45,000 mg/L, and the concentration of heavy metals is basically the same as that of municipal sewage. Leachate from municipal solid waste landfill is a kind of high concentration organic wastewater with complex components. If it is directly discharged into the environment without treatment, it will cause serious environmental pollution. In order to protect the environment, it is necessary to treat the leachate.
1 Present situation of leachate treatment process
The treatment methods of landfill leachate include physical and chemical methods and biological methods. Physical and chemical methods mainly include activated carbon adsorption, chemical precipitation, density separation, chemical oxidation, chemical reduction, ion exchange, membrane dialysis, air stripping wet oxidation and so on. When cod is 2000 ~ 4000? When mg/L, the COD removal rate of physicochemical method can reach 50% ~ 87%. Compared with biological treatment, physicochemical treatment is not affected by the change of water quality and quantity, and the effluent quality is relatively stable, especially for landfill leachate with low BOD5/COD ratio (0.07 ~ 0.20), which is difficult to be biologically treated. However, the cost of physical and chemical treatment is high, which is not suitable for treating large amount of landfill leachate, so the biological method is mainly used for landfill leachate.
Biological methods are divided into aerobic biological treatment, anaerobic biological treatment and their combinations. Aerobic treatment includes activated sludge process, aeration oxidation tank, aerobic stabilization tank, biological turntable and trickling filter. Anaerobic treatment includes upflow sludge bed, anaerobic immobilized bioreactor, mixing reactor and anaerobic stabilization tank.
2 Introduction of Leachate Treatment
Landfill leachate has different characteristics from ordinary urban sewage, such as high concentrations of BOD5 and COD, high metal content, great changes in water quality and quantity, high ammonia nitrogen content and unbalanced microbial nutrition. Among the treatment methods of leachate, combining leachate with municipal sewage is the simplest method. However, landfills are usually far away from towns, so there are some specific difficulties in the joint treatment of leachate and municipal sewage, and they often have to be treated separately. Common treatment methods are as follows.
2. 1 aerobic therapy
Successful experience in treating leachate by aerobic methods such as activated sludge method, oxidation ditch, aerobic stabilization pond and biological turntable. Aerobic treatment can effectively reduce BOD5, COD and ammonia nitrogen, and can also remove other pollutants such as iron and manganese. Among aerobic methods, the most widely used method is extended aeration, as well as aeration stabilization pond and biological turntable (mainly used for nitrogen removal). The following will be introduced separately.
2. 1. 1 activated sludge process
2. 1. 1. 1 traditional activated sludge process
Leachate can be treated by biological method, chemical flocculation method, activated carbon adsorption method, membrane filtration method, lipid adsorption method and gas stripping method alone or in combination, among which activated sludge method is widely used because of its low cost and high efficiency. The operation results of several activated sludge wastewater treatment plants in the United States and Germany show that the activated sludge process can achieve satisfactory landfill leachate treatment effect by increasing sludge concentration and reducing sludge organic load. For example, the influent CODCr of landfill leachate is 6000 ~ 2 1000 mg/L and BOD5 is? 3000 ~ 13000 mg/l, ammonia nitrogen 200 ~ 2000 mg/L. The sludge concentration (MLVSS) of aeration tank is 6000 ~ 12000mg/L, which is 3 ~ 6 times of the general sludge concentration. When the volume organic load is1.87kg bo D5/(m3 d), the F/M is 0.15 ~ 0.31kg BOD5/(kg mlss d), and the removal rate of BOD5 is 97%. When the volume organic load is 0.3 kg bo D5/(m3 d), the F/M is 0.03 ~ 0.05 kg BOD5/(kg mlss d), and the removal rate of BOD5 is 92%. The data of this factory show that the activated sludge process can effectively treat landfill leachate as long as the concentration of activated sludge process is properly increased and the F/M is between 0.03 ~ 0.31kgbod5/(kg mlss d) (not higher).
Many scholars also found that activated sludge can remove 99% BOD5 from leachate, and more than 80% of organic carbon can be removed by activated sludge. Even if the influent organic carbon is as high as 1000mg/L, the sludge biological phase can adapt and degrade quickly. The activated sludge system running at low load can remove 80% ~ 90% of COD from leachate and produce BOD5.
2. 1. 1.2 anoxic aerobic activated sludge process
Hypoxia? Improved activated sludge processes, such as aerobic activated sludge process and SBR process, are more effective than conventional activated sludge process because they have the characteristics of maintaining high operating load and short time consumption. Does Xu Dimin of Tongji University use hypoxia? Aerobic activated sludge process was used to treat landfill leachate. Experiments show that under controlled operating conditions, landfill leachate can pass through low oxygen? Aerobic activated sludge treatment has a good effect. The average CODCr, BOD5 and SS of the final effluent are lower than before? 6466? mg/L、3502？ Mg/L and 239.6 mg/L were reduced to CODcr.
If the treated wastewater is further treated by chemical coagulation with basic aluminum chloride, the CODCr of the wastewater can be reduced to below1000 mg/L.
The two-stage treatment of nitrogen and phosphorus in leachate is also better than the general biological method. The average removal rate of phosphorus is 90.5%; The average removal rate of nitrogen is 67.5%. In addition, how to run without oxygen? The aerobic two-stage biological treatment method forms more NH3-N in the first stage, which makes the second stage difficult and the two-stage aerobic treatment time is too long.
2. 1. 1.3 Physicochemical activated sludge composite treatment system
Because of the high proportion of refractory polymer compounds in percolating water and the inhibition of existing heavy metals, biological methods and physical methods are often used. The composite system combining chemical method was used to treat landfill leachate. For BOD5? Some scholars have used 1500m g/L, Cl-800mg/L, hardness (calculated by CaCO3) 800mg/L, total iron 600mg/L, organic nitrogen 100mg/L, TSS 300mg/L and SO2-4300mg/L. After the influent in the system passes through the regulating tank, it can avoid the instantaneous high concentration of toxic substances and inhibit activated sludge organisms; Adding lime to the clarifier can remove heavy metals and some organic substances; Blow-off tank (aeration, adding NaOH when the temperature is low) can remove 50% NH3-N from the influent, so that the NH3 concentration is lower than the inhibition level. Because the phosphorus in the wastewater is precipitated by the added lime, the pH value is too high, so it is necessary to add phosphorus and acidic substances; The activated sludge system can be used in series or in parallel, and the conventional method or extended aeration method can be selected by adjusting the proportion of returned sludge during operation, which has great operational flexibility.
2. 1.2 aeration stabilization pond
Compared with activated sludge process, aeration stabilization pond has large volume and low organic load. Although the degradation progress is slow, it is the most economical aerobic biological treatment method for landfill leachate in areas where land is not expensive because of its simple engineering. Small-scale, pilot-scale and production scale studies in the United States, Canada, Britain, Australia and Germany all show that aeration stabilization pond can achieve better treatment effect of landfill leachate.
For example, Britain invested 60,000 pounds in Bryn Posteg landfill to build an aeration oxidation pond with 1000m3, with two surface aeration devices, and the minimum hydraulic retention time was 10d. After precipitation, the effluent from the oxidation pond flows into the urban sewer through a 3 km long pipeline. The system started running on 1983. The maximum CODCr of leachate is 24000mg/L, and the maximum BOD5 is? 10000? Mg/L, F/M = 0.05 ~ 0.3 kg COD/(kg mlss d), the water quantity varies from 0 ~ 150m3/d, and the average BOD5 of the effluent is 24 mg/L. However, when it occasionally exceeds 50mg/L, the COD removal rate reaches 97%, but P needs to be added during operation. With this in mind,
The British Water Research Center conducted a survey of CODcr >: 15000mg/L leachate was also tested in the pilot aeration stabilization pond. When the load is 0.28 ~ 0.32 kg COD/(kg mlss d) or 0.04 ~ 0.64 kg COD/(kg mlss d) and the sludge age is 10d, the removal rates of COD and BOD5 are 98% and 98% respectively. Phosphoric acid also needs to be added during operation. ?
2. 1.3 biofilm method
Compared with activated sludge process, biofilm process has the advantages of resisting water and water impact load, and microorganisms such as nitrifying bacteria can grow on biofilm for a long generation. C. Petty and J. atwater of the University of British Columbia studied CODcr.
2.2 Anaerobic biological treatment
The purposeful application of anaerobic biological treatment has a history of nearly a hundred years. However, in recent 20 years, with the development of microbiology, biochemistry and other disciplines and the accumulation of engineering practice, new anaerobic treatment processes have been continuously developed, which has overcome the characteristics of long hydraulic retention time and low organic load of traditional processes and made great progress in theory and practice. Mg/L) organic wastewater has achieved good results.
Anaerobic biological treatment has many advantages, the most important of which is low energy consumption and simple operation, so the investment and operation cost are low. Moreover, due to the small amount of excess sludge, less nutrients are needed, such as its BOD5/P ratio is only 4000:1. Although the content of P in leachate is usually less than 1mg/L, it can still meet the requirements of microorganisms for P. Under the conditions of 35℃, load1kg COD/(m3 d) and residence time 10d, the removal rate of COD in leachate can reach 90%.
Developed anaerobic biological treatment methods include: anaerobic biofilter, anaerobic contact tank, upflow anaerobic sludge bed reactor and staged anaerobic nitrification.
2.2. 1 anaerobic biofilter
Anaerobic filter is suitable for treating dissolved organic matter. Halifax highway101landfill leachate in Canada has an average COD of 12850mg/L, a BOD5/COD of 0.7 and a pH of 5.6. The leachate is adjusted to pH=7.8 with limewater to precipitate 1h, and then passes through an anaerobic filter (this process also plays a role in removing heavy metals such as Zn). When the load is 4 kg COD/(m3 d), the COD removal rate can reach above 92%. When the load increases again, its removal rate drops sharply.
J. G. Henry of the University of Toronto, Canada, etc. The landfill leachate of 1.5 years and 8 years was successfully treated by anaerobic filter at room temperature, and its COD was 14000mg/L and 4000? The mg/L and BOD5/COD are 0.7 and 0.5, respectively. When the load is1.26 ~1.45 kg COD/(m3 d) and the hydraulic retention time is 24 ~ 96h, the COD removal rate can reach over 90%. When the load increases again, its removal rate also drops sharply. It can be seen that although the load of anaerobic filter can reach 5 ~ 20kg COD/(m3 d) when treating high-concentration organic wastewater, the load of leachate must be kept at a low level in order to obtain ideal treatment effect.
2.2.2 Upflow Anaerobic Sludge Bed
The British Water Research Center reported that the upflow anaerobic sludge bed (UASB) was used to treat leachate with COD >:10000 mg/L. When the load was 3.6 ~19.7 kg COD/(m3 d), the average sludge age was 1.0 ~ 4.3d at 30℃. Their load is much larger than that of anaerobic filters.
During anaerobic decomposition, organic nitrogen is transformed into ammonia nitrogen, NH4+? NH3+H？ +reaction. If NH3 in equilibrium is dominant at pH>7, it can be removed by blowing. However, in the process of anaerobic decomposition, the pH value is about 7, so the effluent may contain more NH4+, which will consume the dissolved oxygen in the receiving water.
2.3 the combination of anaerobic and aerobic way
Although the practice has proved the effectiveness of anaerobic biological method in treating high concentration organic wastewater, it is rare to treat leachate by anaerobic method alone. The anaerobic aerobic treatment process for high concentration landfill leachate is economical and reasonable, and the treatment efficiency is high. The removal rates of COD and BOD are 86.8% and 97.2% respectively.
2.3. 1 anaerobic? Aerobic biological oxidation process (anaerobic nitrification and biological oxidation pond)
The Department of Biology of Southwest Normal University treated the leachate with pH of 8.0 ~ 8.6, COD of 16 124mg/L, BOD5 of 2 14 ~ 406 mg/L and NH3-N of 475mg/L, and the effluent pH was 7./kloc-0.
2.3.2 anaerobic? Oxidation ditch? Bianxingtang craft
The following description and analysis are combined with Guangzhou Likeng landfill. The sewage treatment plant of Likeng Landfill is designed according to the flow rate of 300m3/d, and the influent BOD5 is 2500mg/L, CODCr is 4000mg/L, and NH3-N is? 1000mg/L, SS 600mg/L, chroma 1000 times; The effluent BOD5 is 30mg/L, CODCr is 80mg/L, NH3-N is 10mg/L, SS is 70mg/L, and the chroma is 40 times. The selected technological process is: anaerobic oxidation ditch+facultative pond flocculation and sedimentation. When the influent water quality is good and the effluent from the facultative tank reaches the standard, the facultative tank water can be directly discharged; However, when the influent water quality is poor and the effluent from the facultative tank cannot meet the discharge standard, the coagulation and sedimentation system is started, and then the supernatant of the sedimentation tank is discharged.
From the operation of the process, when the influent COD is high, the effluent quality is better; Once COD is reduced, especially in winter, when the temperature is low and there is little rain, it is not conducive to biochemical treatment, and the effluent water quality components all exceed the standard, and the effluent is brown. Although the flocculation and sedimentation system has been started, the effect is still not ideal. It can be seen that the effective removal of chroma and NH3-N in leachate will have a favorable impact on biochemical treatment.
2.3.3 Anaerobic? Floating? Aerobic process
This process is used to treat leachate in Datianshan Waste Sanitary Landfill. According to the detection data and simulation test of leachate from similar landfill sites by Guangzhou Institute of Environmental Health, the design parameters of leachate sewage treatment are determined in combination with the actual situation of the site. The influent water quality CODCr is 8000mg/L, BOD5 is 5000mg/L, SS is 700mg/L, and pH is 7.5; The effluent quality is CODCr 100mg/L, BOD5 60mg/L, SS 500mg/L, and pH 6.5 ~ 7.5. ? In view of the fact that the site is far away from the urban area, in order to facilitate management and save energy consumption, anaerobic and aerobic combined treatment processes are selected after comparison. The anaerobic stage is an upflow anaerobic sludge bed reactor, and the aerobic stage is a biological contact oxidation process. Increase chemical coagulation and sedimentation and biological oxidation ponds, and purify and discharge them up to standard. The remaining sludge is concentrated and sent back to the landfill for treatment.
Considering the great change of leachate quality, air flotation process was added after anaerobic stage to improve the treatment capacity and cope with the high influent quality.
UASB？ Oxidation ditch stabilization pond
1995 Fuzhou has built the largest modern comprehensive municipal waste treatment plant in China-Fuzhou Hongmiaoling Waste Sanitary Landfill. The amount of water for treating landfill leachate is1000 m3/d; The water quality (inlet) of landfill leachate is CODCr 8000mg/L and BOD5 5500mg/L; The treatment water quality requirements (export) are CODCr removal rate of 95% and BOD5 removal rate of 97%.
This design adopts upflow anaerobic sludge bed. Aubert oxidation ditch? Process flow of stabilization pond. Landfill leachate is concentrated in the storage bin, flows to the water collecting basin and grid by the high terrain of the storage yard, flows to the distribution basin by potential energy after being metered by the Bartholian metering box, and then flows to the upflow anaerobic sludge bed by the static head. After anaerobic treatment, the sewage flows into the sedimentation tank for solid-liquid separation, the supernatant flows to the Ober oxidation ditch by itself, the precipitated sludge is discharged into the sludge pool by gravity, and the sludge is regularly sent to the landfill or composted by a tanker.
Aubert oxidation ditch is used for aerobic biochemical treatment of sewage, and three ditch A/O process is adopted, which has advanced nitrogen removal effect. The outstanding advantage of this process is that the first ditch can nitrify ammonia nitrogen, and BOD can denitrify nitrate, and the total nitrogen removal rate can reach 80%. Because BOD in sewage is used as carbon source, BOD5 in sewage is removed and oxygen demand in sewage is reduced. In order to improve the denitrification effect of oxidation ditch, the effluent from the third ditch was pumped to the first ditch by submersible pump for reflux denitrification in the first ditch.
Sewage treated by oxidation ditch flows into the secondary sedimentation tank for solid-liquid separation, and clarified water flows into the stabilization pond for biological treatment. Excess sludge from the secondary sedimentation tank is discharged to the concentration tank by gravity. The supernatant in the concentration tank flows back to the oxidation ditch for treatment, and the concentrated sludge is pumped to the tanker by submersible pump and transported to the landfill for landfill or composting. ?
2.4 Land treatment
Land treatment method, namely soil irrigation method, is the earliest sewage treatment method adopted by human beings, but the application of land treatment system in urban sewage treatment is more common. For the treatment method of leachate, the leachate is collected by sprinkler irrigation and returned to the landfill. The leachate from the circulating landfill increases the humidity of the garbage, thus improving the biological activity and accelerating the generation of methane and the decomposition of the garbage. Secondly, because of evaporation in sprinkler irrigation, the volume of leachate is reduced, which is beneficial to the operation of sewage treatment system and can save energy costs. Part of Seamer Carr landfill in northern England uses leachate for recycling. After 20 months, the COD value and metal concentration of leachate in the circulating area decreased significantly, while the concentrations of NH3-N and Cl- changed little. It shows that the reduction of metal concentration is not only caused by dilution, but also by the adsorption of inorganic components in garbage.
Because of the advantages of circulating leachate, the top of landfill should not be completely closed in design, but ditches should be arranged regularly to avoid pollution to surrounding water sources. Low-concentration leachate cannot be directly discharged, because the concentrations of NH3-N and Cl- are still high, the seasonal temperature is low, the evaporation is low, and the biological activity is weak, so the reuse effect of leachate needs further study.
2.5 nitrification and denitrification
The old landfill is often in the stage of biogas fermentation, and the ammonia nitrogen content in its leachate is high, usually100 ~1000 mg/L. There are two main methods to remove ammonia nitrogen: one is nitrification and denitrification; The other is to raise the pH value to above 9, and then blow it off with air. Robinson and Maris aerated the landfill leachate for 20 years at the temperature of 65438 00℃ and the sludge age of 60 days (in fact, this is similar to the operating conditions of oxidation pond), and it can be completely nitrated. Other aerobic methods such as biological rotary table have also achieved success, so it is generally considered that nitrification of leachate is not a problem.
Common processing flow:
(1) nitrification/denitrification system +MBR+RO
Nitrification/denitrification process is a biochemical treatment method to remove ammonia nitrogen. Through the joint action of nitrification and denitrification, COD and ammonia nitrogen can be completely removed simultaneously. Through MBR mud-water separation and RO deep ion interception, the effluent finally reaches the national discharge standard.
(2) Two-stage reverse osmosis process (or two-stage DTRO process or full membrane treatment process)
This process is a purely physical treatment method, which occupies a small area and has a short construction and debugging period. However, it is easy to cause the enrichment of pollutants, it is difficult to achieve long-term stable effluent standards, and the one-time investment and operating costs are high.
(3) Flocculation and sedimentation+nitrification/denitrification system +MBR+NF+RO
This process is mostly made into integrated equipment, and chemical pretreatment is added at the front end, which makes the process route longer and increases the overall control difficulty. The integrated equipment has poor adaptability to the fluctuation of water quality and quantity, and is prone to problems such as small tank capacity and poor biochemical effect.
(4) mesophilic anaerobic system+nitrification/denitrification +MBR+RO
The removal effect of high concentration COD is good, and it is often used to treat fresh landfill leachate such as garbage incineration plants and garbage transfer stations. The process requires high influent stability, and the anaerobic system should be kept at 35℃, which has high investment and operation costs.
2.6 British Rochem Reverse Osmosis Treatment Plant
The British landfill leachate treatment plant adopts the disc-tube reverse osmosis system patented by Rochem to treat the primary leachate. This treatment technology is a Rochem separation membrane system designed and produced by Winterton Landfill in South Humberside.
The core of this system is Rochem's patented disc tube. The cylinder is composed of plate, octagonal steel and wear-resistant membrane pad in a circular tube, which can treat leachate that quickly blocks the common reverse osmosis membrane system. Under the pressure of membrane, leachate enters the treatment system of Rochem for aeration and pH correction. When the leachate containing pollutants flows through the inner surface of the cylinder, the pollutants in the leachate are separated by reverse osmosis and discharged through the membrane. The cleaning operation of the whole system is automatic. When the system needs chemical cleaning, the control indicator will display information, and the automatic cleaning system will use programmed chemicals to clean the system internally to restore its original function. Because the leachate forms turbulence on the membrane surface under closed conditions, reducing oxidation and producing stench, it needs to be cleaned internally within a certain period of time, but the interval of such cleaning is long. Rochem's separation membrane system can remove heavy metals, solid suspended solids, ammonia nitrogen and harmful refractory organic substances, and the treated water meets strict discharge standards.
Rochem's treatment system was installed and put into use in Ihlenbery landfill in Germany, with a treatment capacity of 50m3/h and a water recovery rate of 90%.
Introduction of Municipal Landfill Leachate Treatment Process from Free paper net
Analysis and comparison of three treatment processes
Compared with aerobic method, anaerobic biological treatment has the following advantages.
(1) Aerobic method requires energy (air compressor, rotary brush, etc. ), and anaerobic treatment can produce energy (methane gas). The higher the COD concentration, the more energy is consumed by aerobic process. The larger the capacity of anaerobic process, the more obvious the difference between them.
(2) The ratio of organic matter to sludge in anaerobic treatment (0. 1kgMLSS/kgCODCr) is much less than that in aerobic treatment (0.5kgMLSS/kgCODCr), so the cost of sludge treatment and disposal is greatly reduced.
(3) Anaerobic treatment is suitable for treating landfill leachate with low phosphorus content, because the sludge growth is small and the requirements for inorganic nutrients are much lower than those of aerobic treatment.
(4) It is reported that many halogen organic compounds which are difficult to treat under aerobic conditions can be biodegraded under anaerobic conditions.
(5) The organic load of anaerobic treatment is high, and the occupied area is relatively small.
However, the concentration of COD and ammonia nitrogen in the effluent from anaerobic treatment is still high, and the dissolved oxygen is very low, which is not suitable for direct discharge into rivers or lakes, and generally requires subsequent aerobic treatment. In addition, most of the landfill leachate in the world is acidic (pH value is generally 5.5 ~ 7.0). When the pH is lower than 7, methanogenic bacteria will be inhibited or even killed, which is not conducive to anaerobic treatment. However, aerobic treatment has less strict requirements on pH, and the optimal temperature for anaerobic treatment is 35℃. When the temperature is lower than 35℃, the treatment efficiency drops rapidly. Comparatively speaking, aerobic treatment does not need high temperature, and even if the water temperature is not controlled in winter, it can still achieve better effluent quality.
In view of the above reasons, anaerobic treatment (post-aerobic treatment) is recommended for high-concentration landfill leachate with COD concentration above 50 000mg/L, and aerobic biological treatment is recommended for landfill leachate with COD concentration below 5 000 mg/L. For landfill leachate with COD between 5 000 and 50 000 mg/L, aerobic or anaerobic methods can be adopted, and other factors are mainly considered when selecting the process.
4 Conclusions and suggestions
Through the analysis and comparison of the above treatment methods and processes, the following conclusions can be drawn, and suggestions and opinions on water quality and quantity are put forward:
(1) Landfill Leachate has the characteristics of complex composition, great variation of water quality and quantity, high concentration of organic matter and ammonia nitrogen, and imbalance of microbial nutrients. Therefore, when selecting the biological treatment process of landfill leachate, it is necessary to determine the composition of landfill leachate in detail and analyze its characteristics in order to take corresponding countermeasures. It is also necessary to obtain reliable optimized process parameters through small-scale test and pilot test in order to obtain ideal treatment effect.
(2) It is feasible to treat leachate by various methods. It can not only save investment, but also reduce operating cost to build a biological pool and use aquatic plant system to treat leachate where conditions permit. People also pay attention to land treatment, but it is rarely used for leachate treatment. Biofilm process and activated sludge process have mature operation and management experience, and more leachate is treated by anaerobic aerobic process. However, the construction of a special leachate treatment plant has a large investment, high operation and management costs, and with the closure of the landfill, the water treatment facilities will eventually be scrapped, so it should be carefully selected.
(3) There are not many landfills that can really meet the sanitary landfill standards in China. Due to limited investment, many landfills cannot build leachate collection systems that can meet the environmental protection requirements according to the design requirements. Therefore, it is desirable to develop leachate treatment technology with less investment and good effect. Leachate from landfill is reinjected into landfill and degraded by land adsorption, soil biodegradation and anaerobic filter bed in landfill, which has the characteristics of low investment, good effect and no need for special treatment facilities investment. In addition, leachate recharge can keep the garbage moist and accelerate the stability of landfill. Recharge method is rarely used, so it can be further studied to clarify the use conditions, treatment efficiency and engineering design parameters of recharge method.
(4) The treatment of landfill leachate is one aspect of the problem, on the other hand, we should consider reducing the amount of leachate. It is suggested to develop landfill technology that can reduce leachate production, such as aerobic landfill or semi-aerobic landfill.
(5) The treatment of landfill leachate is still in the stage of research and exploration in China. In order to build a standardized sanitary landfill of municipal solid waste, it is necessary to conduct in-depth research on the treatment of landfill leachate.