Treatment method of high-salinity landfill leachate

Abstract

The invention belongs to the technical field of wastewater treatment, and discloses a treatment method of high-salinity landfill leachate. The treatment method of the landfill leachate comprises the following steps: taking activated sludge of a landfill leachate treatment plant, and carrying out salt-tolerant domestication treatment to obtain salt-tolerant activated sludge; the method comprises the following steps: inoculating salt-resistant activated sludge into an anaerobic zone of a reaction system, and feeding the landfill leachate into the anaerobic zone for preliminary degradation; effluent of the anaerobic zone flows into the anoxic zone of the reaction system for denitrification; effluent of the anoxic zone flows into a biological contact oxidation zone of the reaction system for nitrification and partial nitrosation; nitrification liquid in the biological contact oxidation zone flows back into the anoxic zone; wherein the reflux ratio of the nitrification liquid is 200%-300%. According to the treatment method of the landfill leachate, the high-salinity landfill leachate can be effectively treated, and nitrogen in the high-salinity landfill leachate can be efficiently converted and removed.

Description

Technical Field

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

[0002] With the acceleration of urbanization, the problem of urban domestic waste treatment is becoming increasingly prominent. Landfill is a widely used method of waste treatment, but the leachate generated during the landfill process is a highly polluted wastewater containing a large amount of organic matter and inorganic salts. If it is not effectively treated, it will cause serious pollution to groundwater, surface water and the surrounding environment, threatening human health.

[0003] The water quality of landfill leachate is complex, and there are many kinds of organic matter, including low molecular weight fatty acids, medium molecular weight fulvic acid substances, high molecular weight carbohydrate substances, humus, etc. The organic components in landfill leachate change with the landfill time. In the early stage, short-chain volatile fatty acids are the main components. With the increase of landfill time, fulvic acid and humus components increase. In addition, the concentration of pollutants in leachate is high and the range of variation is large. The concentration of BOD5 and COD can reach tens of thousands of milligrams per liter, and it contains a variety of metal ions.

[0004] Traditional methods for treating landfill leachate include physical, chemical and biological methods. Among them, biological methods have gradually become the preferred process due to their low energy consumption and no secondary pollution. However, the high salt content and high toxicity in landfill leachate pose severe challenges to the biological treatment process. Current technologies for treating high-salinity landfill leachate mainly include traditional biological treatment processes, such as activated sludge method and biofilm method. However, these processes have obvious limitations when treating high-salinity landfill leachate: high salinity will inhibit the activity of microorganisms, reduce the efficiency of biological treatment, and even cause the death of microorganisms.

[0005] Therefore, how to effectively treat high-salinity landfill leachate is a technical problem that needs to be solved urgently in this field. Summary of the invention

[0006] The present invention aims to solve at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a method for treating high-salinity landfill leachate, which can effectively treat high-salinity landfill leachate and efficiently transform and remove nitrogen in high-salinity landfill leachate.

[0007] A first aspect of the present invention provides a method for treating landfill leachate, comprising the following steps:

[0008] Taking activated sludge from a landfill leachate treatment plant, subjecting it to salt tolerance acclimation treatment, to obtain salt-tolerant activated sludge;

[0009] Inoculate the salt-tolerant activated sludge into the anaerobic zone of the reaction system, and then send the landfill leachate into the anaerobic zone for preliminary degradation;

[0010] The effluent from the anaerobic zone flows into the anoxic zone of the reaction system for denitrification;

[0011] The effluent from the anoxic zone flows into the biological contact oxidation zone of the reaction system for nitrification and partial nitritation;

[0012] The nitrified liquid from the biological contact oxidation zone is recycled back to the anoxic zone;

[0013] Among them, the nitrified liquid reflux ratio is 200%-300%.

[0014] Specifically, the present invention combines the advantages of A 2 O (anaerobic-anoxic-aerobic) and the biological contact oxidation method, and conducts salt tolerance domestication on the activated sludge to construct a suitable biological treatment system; in the A 2 O process, the anaerobic zone realizes the preliminary degradation of organic matter and the reduction of sludge; the anoxic zone uses nitrate in the nitrified liquid for denitrification and nitrogen removal, and controls the nitrified liquid reflux ratio to be 200%-300% to ensure that there is enough nitrate nitrogen in the anoxic zone for denitrification and nitrogen removal; the biological contact oxidation zone realizes the nitrification and partial nitritation of ammonia nitrogen. As a substitute and extension of aerobic, the biological contact oxidation zone further strengthens the nitritation and denitrification processes, realizes short-cut nitrification and denitrification, and thus realizes the effective treatment of high-salt landfill leachate.

[0015] In some embodiments of the present invention, it further includes the step of adding a carbon source to the anoxic zone, and the dosage of the carbon source is 0.5-1.5 kg COD / (m 3 ·d).

[0016] Specifically, in the anoxic zone, in order to meet the carbon source demand of the denitrification process, it is necessary to add a carbon source in a timely manner. The carbon source includes but is not limited to methanol, sodium acetate, and glucose, and preferably methanol. As an easily biodegradable organic carbon source, methanol can be effectively utilized by denitrifying bacteria for denitrification and nitrogen removal. If the dosage of the carbon source is insufficient, it is easy to cause limited metabolism of denitrifying bacteria; if the dosage of the carbon source is too much, it will increase the operating cost and affect COD removal.

[0017] Specifically, the activated sludge is taken from the aeration nitrification tank of a landfill leachate treatment plant. This sludge has a rich microbial population, has adapted to the water quality characteristics of landfill leachate, and has good biological activity.

[0018] In some embodiments of the present invention, the pH value of the activated sludge is 8.0 - 8.5; and / or, the MLSS of the activated sludge is 3000 - 4500 mg / L; and / or, the MLVSS of the activated sludge is 2000 - 3000 mg / L.

[0019] In some embodiments of the present invention, the steps of the salt tolerance acclimation treatment include: placing the activated sludge in wastewater with a certain salinity for acclimation, the initial value of the salinity being 5 g / L, and gradually increasing the salinity to a target value of 20 g / L. Through the acclimation process of gradually increasing the salinity, the present invention screens out activated sludge with high salt tolerance and degradation ability. During the acclimation process, by monitoring indicators such as the sedimentation performance, biological activity, and nitrogen conversion efficiency of the sludge, the acclimation conditions are optimized to ensure the stable reproduction and efficient degradation of salt-tolerant bacteria.

[0020] Specifically, the salt tolerance acclimation process is divided into three stages: preliminary acclimation, optimization acclimation, and screening and propagation.

[0021] Preliminary acclimation: Place the activated sludge in wastewater with a certain salinity for acclimation, the initial value of the salinity being 5 g / L, and gradually increase the salinity to a target value of 20 g / L at a rate of 1 - 3 g / L (simulating the environment of high-salt landfill leachate), while monitoring the growth of the sludge and the degradation efficiency. In the initial stage of acclimation, the growth of the sludge may be inhibited, but by gradually increasing the salinity and optimizing the environmental conditions, the sludge will gradually adapt to the high-salt environment.

[0022] Optimization acclimation: According to the results of the preliminary acclimation, adjust the salinity increase rate and the wastewater composition to further optimize the acclimation conditions. For example, during the process of increasing the salinity, the dosage of carbon sources (such as glucose, methanol, etc.) can be appropriately increased to provide the energy required for microbial growth. At the same time, by adjusting environmental factors such as the pH value and temperature, an environment conducive to the growth of salt-tolerant bacteria is created.

[0023] Screening and propagation: Through continuous flow experiments, screen out activated sludge with high salt tolerance and degradation ability, and carry out propagation for standby. During the screening process, indicators such as the sedimentation performance, biological activity, and nitrogen conversion efficiency of the sludge can be monitored to ensure that the screened sludge has excellent treatment performance.

[0024] After the salt tolerance acclimation of the sludge, its salt tolerance and biological activity are significantly improved, and it can efficiently treat high-salt landfill leachate.

[0025] In some embodiments of the present invention, the dissolved oxygen concentration in the biological contact oxidation zone is 1-4 mg / L. In the biological contact oxidation zone, by adjusting the aeration volume to control the dissolved oxygen concentration and controlling the dissolved oxygen concentration at a relatively low level (such as 1-4 mg / L), the formation of nitrate can be inhibited, and ammonia nitrogen can be mainly converted into nitrite nitrogen, ensuring the stable progress of the short-cut nitrification process.

[0026] In some embodiments of the present invention, the operation stages of the reaction system include a startup stage and a stable operation stage. The intermittent influent mode is adopted in the startup stage, and the continuous influent mode is adopted in the stable operation stage.

[0027] In some embodiments of the present invention, the operation parameters in the startup stage include at least one of the following: the average daily treatment water volume is 30%-40% of the total effective volume of the reaction system; the ammonia nitrogen volume load is 0.3-0.4 kg N / (m 3 ·d); the sludge retention time is 15-20 d.

[0028] In some embodiments of the present invention, the operation parameters in the stable operation stage include at least one of the following: the average daily treatment water volume is 65%-75% of the total effective volume of the reaction system; the ammonia nitrogen volume load is 0.6-0.8 kg N / (m 3 ·d); the sludge retention time is 8-12 d.

[0029] Specifically, in the startup stage and the initial stage of operation, the sludge retention time can be appropriately extended (such as 15-20 d) to promote the growth and reproduction of salt-tolerant bacteria. In the stable operation stage, with the stable operation of the system and the optimization of the microbial population structure, the sludge retention time can be gradually shortened (such as 8-12 d) to improve the treatment efficiency and stability of the system.

[0030] In some embodiments of the present invention, before the landfill leachate is sent into the anaerobic zone, the landfill leachate is first sent into the regulating tank, and the regulating tank is used for regulating the flow rate and equalizing the water quality, and plays a pretreatment role.

[0031] In the second aspect of the present invention, a reaction system for the treatment method of the landfill leachate described in the first aspect of the present invention is provided. Along the water flow direction, the reaction system includes an anaerobic zone, an anoxic zone, and a biological contact oxidation zone.

[0032] In some embodiments of the present invention, stirring devices are provided in both the anaerobic zone and the anoxic zone; a packing layer is provided in the biological contact oxidation zone, and a biological film is attached to the packing layer.

[0033] In some embodiments of the present invention, the size of the anaerobic zone is 1.2 m×1.5 m×1.2 m (length×width×height), and the effective volume is 1.8 m3 The stirring device in the anaerobic zone can ensure the full mixing of leachate and sludge, promoting the preliminary degradation of organic matter and the reduction of sludge volume.

[0034] In some embodiments of the present invention, the size of the anoxic zone is 0.6m×1.5m×1.2m (length×width×height), and the effective volume is 0.9m 3 The anoxic zone receives part of the nitrified liquid refluxed from the biological contact oxidation zone for denitrification. The nitrified liquid is rich in nitrate nitrogen. Through the action of denitrifying bacteria in the anoxic zone, the nitrate nitrogen is reduced to nitrogen gas to achieve the purpose of nitrogen removal.

[0035] In some embodiments of the present invention, the size of the biological contact oxidation zone is 1.8m×1.5m×1.2m (length×width×height), and the effective volume is 2.7m 3 The biological contact oxidation zone, as an alternative and extension of aerobic treatment, further strengthens the nitritation and denitrification processes. The microorganisms in the biofilm in the biological contact oxidation zone can efficiently convert ammonia nitrogen into nitrite nitrogen and further carry out denitrification for nitrogen removal.

[0036] In some embodiments of the present invention, the reaction system further includes a regulating tank, and the water outlet end of the regulating tank is connected to the water inlet end of the anaerobic zone.

[0037] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0038] (1) High efficiency: The present invention domesticates the activated sludge to be salt-tolerant, and combines the A 2 O process with the biological contact oxidation method to treat high-salinity landfill leachate, realizing the efficient conversion and removal of nitrogen, significantly improving the removal rates of COD, ammonia nitrogen and total nitrogen, and the nitritation rate is stable above 95%.

[0039] (2) Economy: The present invention does not require complex physical or chemical treatment equipment, reducing the treatment cost; at the same time, by optimizing the operating parameters (nitrified liquid reflux ratio, carbon source dosage, sludge retention time), the treatment efficiency is improved and the energy consumption is reduced.

[0040] (3) Adaptability: The treatment method of the present invention is applicable to the treatment of high-salinity landfill leachate, solving the application problems of traditional biological treatment processes in high-salt environments.

[0041] (4) Environmental protection: The present invention has no secondary pollution and meets the environmental protection requirements. Brief Description of the Drawings

[0042] Figure 1 It is a schematic structural diagram of the reaction system adopted by the treatment method of the present invention.

[0043] Reference numerals: 100, regulating pond; 200, anaerobic zone; 300, anoxic zone; 400, biological contact oxidation zone. Detailed implementation manners

[0044] The content of the present invention will be further described in detail below through specific embodiments. The raw materials, reagents or devices used in the embodiments can be obtained from conventional commercial channels or can be obtained by existing technical methods without special instructions. Unless otherwise specified, the test or measurement methods are all conventional methods in the art.

[0045] Embodiment 1

[0046] The leachate of this embodiment is taken from the raw leachate of a domestic waste sanitary landfill, and its main water quality indicators are shown in Table 1.

[0047] Table 1

[0048] Parameter Value COD (Chemical Oxygen Demand) (mg / L) 2145±151 Ammonia Nitrogen (mg / L) 504±45 Total Nitrogen (mg / L) 810±71 Salinity (mg / L) 20058±1050 pH 7.5-8.5 Total Phosphorus (mg / L) 15±2 SS (Suspended Solids) (mg / L) 1200±200

[0049] The activated sludge of this embodiment is taken from the aeration nitrification tank of the same leachate treatment plant, and its initial parameters are as follows: pH value is 8.24, MLSS (mixed liquor suspended solids concentration) is 3637 mg / L, MLVSS (mixed liquor volatile suspended solids concentration) is 2562 mg / L, and MLVSS / MLSS is 0.70.

[0050] The reaction system for treating leachate in this embodiment is as Figure 1 shown. Along the water flow direction, the reaction system includes a regulating pond 100, an anaerobic zone 200, an anoxic zone 300, and a biological contact oxidation zone 400; wherein, stirring devices are provided in both the anaerobic zone 200 and the anoxic zone 300; a packing layer is provided in the biological contact oxidation zone 400, and a biological film is attached to the packing layer.

[0051] The method for treating leachate provided in this embodiment includes the following steps:

[0052] Placing the activated sludge in wastewater containing a certain salinity for salt tolerance acclimation treatment, wherein the initial salinity of the wastewater is 5 g / L, and the salinity is gradually increased to the target value of 20 g / L at a rate of 1 g / L. After the acclimation is completed, salt-tolerant activated sludge is obtained;

[0053] Inoculating the salt-tolerant activated sludge into the anaerobic zone of the reaction system;

[0054] Start the reaction system. After the landfill leachate is pretreated in the regulating tank, it is sent to the anaerobic zone for preliminary degradation. The effluent from the anaerobic zone flows into the anoxic zone of the reaction system for denitrification, and the effluent from the anoxic zone flows into the biological contact oxidation zone of the reaction system for nitrification and partial nitritation. The nitrified liquid in the biological contact oxidation zone is recycled back to the anoxic zone. During the startup phase, by gradually increasing the influent load and adjusting the operating parameters, the system gradually adapts to the treatment of high-salinity landfill leachate. The specific operating parameters are as follows:

[0055] Startup phase (30 days): Average daily treatment volume: 1.8 m 3 / d; Ammonia nitrogen volume load: 0.3 kg N / (m 3 ·d); Dissolved oxygen concentration: 2 mg / L; Nitrified liquid reflux ratio: 200%; Methanol dosage: 0.5 kg COD / (m 3 ·d); Sludge retention time: 15 d;

[0056] Steady operation phase (180 days): Average daily treatment volume: 3.6 m 3 / d; Ammonia nitrogen volume load: 0.6 kg N / (m 3 ·d); Dissolved oxygen concentration: 1 mg / L; Nitrified liquid reflux ratio: 200%; Methanol dosage: 1.0 kg COD / (m 3 ·d); Sludge retention time: 8 d.

[0057] For the landfill leachate treatment method provided in this example, the treatment effect on landfill leachate is shown in Table 2.

[0058] Table 2

[0059] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2145 805 62.5％ Ammonia Nitrogen 504 53 89.5％ Total Nitrogen 810 201 75.2％ Nitrification Rate / / Above 95%

[0060] As can be seen from Table 2, in this example, by subjecting the activated sludge to salt tolerance domestication and combining AO with the biological contact oxidation method and optimizing the operating parameters, high-salinity landfill leachate can be effectively treated, significantly improving the removal rates of COD, ammonia nitrogen, and total nitrogen, and the nitritation rate is stable above 95%. 2 Example 2

[0061] The landfill leachate in this example is taken from the original leachate of a certain landfill incineration plant, and its main water quality indicators are shown in Table 3.

[0062] Table 3

[0063] Table 3

[0064]

[0065]

[0066] The activated sludge in this example was taken from the aeration nitrification tank of the same landfill leachate treatment plant, and its initial parameters were as follows: the pH value was 8.01, the MLSS (mixed liquor suspended solids concentration) was 4052 mg / L, the MLVSS (mixed liquor volatile suspended solids concentration) was 2863 mg / L, and the MLVSS / MLSS was 0.71.

[0067] The reaction system for treating landfill leachate in this example was the same as that in Example 1.

[0068] The treatment method for landfill leachate provided in this example includes the following steps:

[0069] The activated sludge was placed in wastewater with a certain salinity for salt tolerance acclimation treatment. The initial salinity of the wastewater was 5 g / L, and the salinity was gradually increased by 1 g / L to the target value of 20 g / L. After the acclimation was completed, salt-tolerant activated sludge was obtained;

[0070] The salt-tolerant activated sludge was inoculated into the anaerobic zone of the reaction system;

[0071] The reaction system was started. The landfill leachate was pretreated in the regulating tank and then sent to the anaerobic zone for preliminary degradation. The effluent from the anaerobic zone flowed into the anoxic zone of the reaction system for denitrification, and the effluent from the anoxic zone flowed into the biological contact oxidation zone of the reaction system for nitrification and partial nitritation. The nitrification liquid in the biological contact oxidation zone was refluxed to the anoxic zone; During the startup stage, by gradually increasing the influent load and adjusting the operating parameters, the system was gradually adapted to the treatment of high-salinity landfill leachate; The specific operating parameters were as follows:

[0072] Startup stage (30 days): Average daily treatment volume: 2.0 m 3 / d; Ammonia nitrogen volume load: 0.4 kg N / (m 3 ·d); Dissolved oxygen concentration: 4 mg / L; Nitrification liquid reflux ratio: 300%; Methanol dosage: 1.0 kg COD / (m 3 ·d); Sludge retention time 20 d;

[0073] Stable operation stage (240 days): Average daily treatment volume: 4.0 m 3 / d; Ammonia nitrogen volume load: 0.8 kg N / (m 3 ·d); Dissolved oxygen concentration: 2 mg / L; Nitrification liquid reflux ratio: 300%; Methanol dosage: 1.5 kg COD / (m 3 ·d); Sludge retention time 12 d.

[0074] The treatment effect of the landfill leachate by the treatment method provided in this example is shown in Table 4.

[0075] Table 4

[0076] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2618 997 61.9％ Ammonia Nitrogen 617 61 90.1％ Total Nitrogen 1160 244 79％ Nitrification Rate / / Above 95%

[0077] As can be seen from Table 4, this embodiment further verifies the high efficiency and stability of the present invention in the treatment of high-salinity landfill leachate. By subjecting the activated sludge to salt tolerance domestication and combining A 2 / O with the biological contact oxidation method and optimizing the operating parameters, COD, ammonia nitrogen, and total nitrogen can be effectively removed, and the nitritation rate is stable above 95%, which is applicable to the treatment of landfill leachate with higher salinity.

[0078] Comparative Example 1

[0079] The difference from Example 1 is only that in Comparative Example 1, the nitrified liquid reflux ratio in the stable operation stage is adjusted to 180%, and the other treatment conditions are the same as those in Example 1.

[0080] The treatment effect of Comparative Example 1 on landfill leachate is shown in Table 5.

[0081] Table 5

[0082] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2187 1210 44.7％ Ammonia Nitrogen 512 102 80.1％ Total Nitrogen 823 345 58.1％ Nitrification Rate / / 85％

[0083] As can be seen from Table 5, when the nitrified liquid reflux ratio is reduced to 180%, the denitrification efficiency decreases significantly, resulting in the total nitrogen removal rate dropping from 75.2% in Example 1 to 58.1%. Due to the insufficient supply of nitrate in the anoxic zone, the nitritation rate synchronously decreases to 85%.

[0084] Comparative Example 2

[0085] The difference from Example 1 is only that in Comparative Example 2, the nitrified liquid reflux ratio in the stable operation stage is adjusted to 320%, and the other treatment conditions are the same as those in Example 1.

[0086] The treatment effect of Comparative Example 2 on landfill leachate is shown in Table 6.

[0087] Table 6

[0088] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2187 980 55.2％ Ammonia Nitrogen 512 75 85.4％ Total Nitrogen 823 298 63.8％ Nitrification Rate / / 88％

[0089] As can be seen from Table 6, too high a reflux ratio (320%) causes fluctuations in the dissolved oxygen concentration in the aerobic zone, inhibits the activity of nitrifying bacteria, and the nitritation rate drops to 88%. At the same time, the excessive reflux of nitrified liquid dilutes the carbon source concentration in the anoxic zone, reducing the denitrification efficiency, and the total nitrogen removal rate is only 63.8%, significantly lower than 75.2% in Example 1.

[0090] Comparative Example 3

[0091] The difference from Example 1 is only that in Comparative Example 3, the methanol dosage in the stable operation stage is adjusted to 0.3 kg COD / (m 3 ·d), and the other treatment conditions are the same as those in Example 1.

[0092] The treatment effect of Comparative Example 3 on landfill leachate is shown in Table 7.

[0093] Table 7

[0094] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2095 1320 37.0％ Ammonia Nitrogen 501 120 76.0％ Total Nitrogen 802 420 47.6％ Nitrification Rate / / 82％

[0095] As can be seen from Table 7, insufficient carbon source leads to limited metabolism of denitrifying bacteria, and the total nitrogen removal rate drops significantly to 47.6%, and the nitritation rate decreases to 82%.

[0096] Comparative Example 4

[0097] The difference from Example 1 is only that in Comparative Example 4, the methanol dosage in the stable operation stage is adjusted to 2.0 kg COD / (m 3 ·d), and the remaining treatment conditions are the same as those in Example 1.

[0098] The treatment effect of Comparative Example 4 on landfill leachate is shown in Table 8.

[0099] Table 8

[0100] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2095 890 57.5％ Ammonia Nitrogen 501 68 86.4％ Total Nitrogen 802 235 70.7％ Nitrification Rate / / 93％

[0101] As can be seen from Table 8, although the excessive carbon source has little effect on the total nitrogen removal rate (70.7%), it causes the effluent COD to increase (890 mg / L), and the operating cost increases significantly, resulting in a decline in economy. It shows that the upper limit of the carbon source dosage in the present invention (1.5 kg COD / (m 3 ·d)) is the optimal value for balancing efficiency and economy.

[0102] Comparative Example 5

[0103] The difference from Example 1 is only that in Comparative Example 5, the sludge retention time in the stable operation stage is adjusted to 5 d (days), and the remaining treatment conditions are the same as those in Example 1.

[0104] The treatment effect of Comparative Example 5 on landfill leachate is shown in Table 9.

[0105] Table 9

[0106] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2128 1150 46.0％ Ammonia Nitrogen 511 95 81.4％ Total Nitrogen 822 380 53.8％ Nitrification Rate / / 93％

[0107] As can be seen from Table 9, too short sludge retention time leads to insufficient reproduction of salt-tolerant bacteria, reduced biological activity, the total nitrogen removal rate drops to 53.8%, and the nitritation rate is only 84%.

[0108] Comparative Example 6

[0109] The difference from Example 1 is only that in Comparative Example 6, the sludge retention time in the stable operation stage is adjusted to 15 d (days), and the remaining treatment conditions are the same as those in Example 1.

[0110] The treatment effect of Comparative Example 6 on landfill leachate is shown in Table 10.

[0111] Table 10

[0112] Parameter Inlet Concentration (mg / L) Outlet Concentration (mg / L) Removal Rate (%) COD 2128 920 56.8％ Ammonia Nitrogen 511 60 88.3％ Total Nitrogen 822 260 68.4％ Nitrification Rate / / 94％

[0113] As can be seen from Table 10, although a too long sludge retention time has a relatively high ammonia nitrogen removal rate (88.3%), the treatment efficiency of the system decreases (the daily average treatment volume decreases), and the risk of sludge aging increases, resulting in the total nitrogen removal rate (68.4%) still being lower than 75.2% of Example 1.

[0114] Through the comprehensive analysis of the above-mentioned examples and comparative examples, the present invention optimizes the key parameters of the nitrification liquid reflux ratio (200%-300%), the carbon source dosage (0.5-1.5 kg COD / (m 3 ·d)), and the sludge retention time (8-12 d) in the stable operation stage, and realizes more efficient treatment of high-salt landfill leachate.

[0115] The above has specifically described the preferred embodiments of the present invention, but the present invention is not limited to the described embodiments. Those skilled in the art can also make various equivalent variations or substitutions without departing from the spirit of the present invention, and these equivalent variations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A method for treating landfill leachate, characterized in that: The following steps are involved: Taking activated sludge from a landfill leachate treatment plant, subjecting it to salt tolerance acclimation treatment, to obtain salt-tolerant activated sludge; Inoculating the salt-tolerant activated sludge into the anaerobic zone of the reaction system, and then sending the landfill leachate into the anaerobic zone for preliminary degradation; The effluent from the anaerobic zone flows into the anoxic zone of the reaction system for denitrification; The effluent from the anoxic zone flows into the biological contact oxidation zone of the reaction system for nitrification and partial nitrite formation; The nitrification liquid in the biological contact oxidation zone flows back into the anoxic zone; Wherein, the reflux ratio of the nitrifying liquid is 200%-300%.

2. The method for treating landfill leachate according to claim 1, characterized in that: The step of adding a carbon source to the anoxic zone is also included, wherein the amount of the carbon source added is 0.5-1.5 kg COD / (m 3 ·d).

3. The method for treating landfill leachate according to claim 1, characterized in that: The pH value of the activated sludge is 8.0-8.5; and / or, the MLSS of the activated sludge is 3000-4500 mg / L; and / or, the MLVSS of the activated sludge is 2000-3000 mg / L.

4. The method for treating landfill leachate according to claim 1, characterized in that: The step of salt tolerance acclimation treatment comprises: placing the activated sludge in wastewater with a certain salinity for acclimation, wherein the initial value of the salinity is 5 g / L, and gradually increasing the salinity to a target value of 20 g / L.

5. The method for treating landfill leachate according to claim 1, characterized in that: The dissolved oxygen concentration in the biological contact oxidation zone is 1-4 mg / L.

6. The method for treating landfill leachate according to claim 1, characterized in that: The operation phases of the reaction system include a startup phase and a stable operation phase. The startup phase adopts an intermittent water inlet mode, and the stable operation phase adopts a continuous water inlet mode.

7. The method for treating landfill leachate according to claim 6, characterized in that: The operating parameters of the startup phase include at least one of the following: the average daily treated water volume is 30%-40% of the total effective volume of the reaction system; the ammonia nitrogen volume load is 0.3-0.4 kg N / (m 3 d); The sludge retention time is 15-20 days.

8. The method for treating landfill leachate according to claim 6, characterized in that: The operating parameters of the stable operation stage include at least one of the following: the average daily treated water volume is 65%-75% of the total effective volume of the reaction system; the ammonia nitrogen volume load is 0.6-0.8 kg N / (m 3 d); The sludge retention time is 8-12 days.

9. A reaction system for the method for treating landfill leachate according to any one of claims 1 to 8, characterized in that: Along the water flow direction, the reaction system includes an anaerobic zone, an anoxic zone and a biological contact oxidation zone.

10. The reaction system according to claim 9, characterized in that: The anaerobic zone and the anoxic zone are both provided with stirring devices; the biological contact oxidation zone is provided with a packing layer, and a biological film is attached to the packing layer.

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