Treatment method and treatment device for effluent of landfill leachate membrane bioreactor

Abstract

The invention relates to the field of water treatment, and particularly provides a landfill leachate membrane bioreactor effluent treatment method, which sequentially comprises Fenton pretreatment, quasi-aerobic mineralized refuse bed treatment and ultraviolet radiation Fenton-like advanced treatment, and through mutual cooperation of the three treatment modes and targeted adjustment of process parameters, the effluent of the landfill leachate membrane bioreactor is treated. The effluent of the landfill leachate membrane bioreactor can be purified to be below the emission limit standard, a good operation effect is achieved, the operation is simple, and the popularization is convenient.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a method and a device for treating effluent from a garbage leachate membrane bioreactor. Background Art

[0002] In the process of urban solid waste treatment and disposal, a large amount of landfill leachate will inevitably be produced. Landfill leachate is a special type of wastewater that is extremely difficult to treat. It contains high concentrations of organic matter and nitrogen pollutants. As the landfill life increases, the molecular composition of the organic matter will become more complex and show the characteristics of being difficult to biodegrade, posing a great ecological and environmental safety hazard. At present, the combined process of "pretreatment + membrane bioreactor (MBR) + deep treatment" is often used to treat landfill leachate, but conventional membrane bioreactors are difficult to treat the difficult-to-degrade organic matter in the leachate, and the membrane deep treatment method commonly used in actual projects still has problems such as serious high-pressure membrane pollution and difficulty in treating membrane concentrate.

[0003] The quasi-aerobic mineralized garbage bed (SAARB), designed based on the concept of "waste treatment with waste", is a low-cost and easy-to-operate biotreatment technology for landfill leachate. It uses natural ventilation to form an "aerobic-anoxic-anaerobic" environment inside to improve the removal of various organic and nitrogen pollutants. However, unlike the original landfill leachate, the effluent treated by membrane biological method has a high proportion of refractory organic matter, an imbalanced carbon-nitrogen ratio, and poor biodegradability, which makes it difficult for microorganisms in SAARB to utilize these refractory organic matter, thereby reducing the treatment effect. In addition, with the improvement of environmental protection requirements, the existing treatment system is difficult to reach the limit values ​​of water pollutants directly discharged in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024) (COD is 100 mg / L, total nitrogen is 40 mg / L, and ammonia nitrogen is 25 mg / L).

[0004] Therefore, it is of great significance to develop a water treatment method that can achieve the discharge limit of landfill leachate to ensure the safety of the water environment. Summary of the invention

[0005] The purpose of the present invention is to provide a method for treating the effluent from a membrane bioreactor of landfill leachate, in view of the problem that the existing methods for treating the effluent from a membrane bioreactor of landfill leachate are difficult to meet the emission limit. The method comprises Fenton pretreatment, quasi-aerobic mineralized garbage bed treatment and ultraviolet irradiation Fenton deep treatment. Through the mutual cooperation of the three-stage treatment methods, the effluent from the membrane bioreactor of landfill leachate can be purified to below the emission limit standard. The operation is simple and easy to promote, and the problems of serious high-pressure membrane pollution, difficult concentrated liquid treatment and high energy consumption faced in the existing mainstream treatment process can be effectively solved.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A method for treating landfill leachate comprises the following steps:

[0008] Step 1: Adjust the initial pH of the effluent from the landfill leachate membrane bioreactor to 3-5, and add Fe 2+ and H2O2, and then Fenton pretreatment was performed; among them, Fe 2+ The molar ratio of the addition of Fenton reagent to H2O2 is 1:(4-8); the dosage of Fenton reagent per liter of landfill leachate membrane bioreactor effluent is 40mmol~60mmol;

[0009] Step 2: adjusting the pH of the effluent from the Fenton process to 7-9, filtering the effluent through sedimentation, and recharging the effluent into the semi-aerobic mineralized garbage bed for water treatment;

[0010] Step 3: Adjust the pH of the effluent from the semi-aerobic mineralized garbage bed to 3-5, add Fe 0 and H2O2 to adjust the pH of the treated water to 7-9, precipitate and filter to obtain purified water, wherein the power of ultraviolet light irradiation is 6-20W; per liter of quasi-aerobic mineralized garbage bed effluent, Fe 0 The dosage is 1-3 mmol, and the dosage of H2O2 is 10-20 mmol.

[0011] The method for treating the effluent from the membrane bioreactor of landfill leachate provided by the present invention comprises, in sequence, Fenton pretreatment, quasi-aerobic mineralized garbage bed treatment and ultraviolet irradiation Fenton-like deep treatment. Through the mutual coordination of the three-stage treatment methods and the targeted adjustment of the process parameters, the effluent from the membrane bioreactor of landfill leachate can be purified to below the emission limit standard, thereby achieving good operating results, being simple to operate and being easy to promote.

[0012] The study found that the effluent after Fenton pretreatment can significantly reduce the concentration of organic matter in the effluent of the landfill leachate membrane bioreactor. At the same time, it can destroy the benzene ring structure of organic matter in sewage and reduce the degree of humification, thereby improving the biodegradability of the effluent of the landfill leachate membrane bioreactor. Reinjection of Fenton effluent can alleviate the instability of SAARB operation and significantly improve the removal effect of mineralized garbage bed on organic matter and nitrogen pollutants in sewage. In addition, through high-throughput sequencing of microorganisms in mineralized garbage, it was found that the re-injection of Fenton effluent affected the composition of the 16S_bacteria community, and the enrichment of functional microorganisms Syntrophaceticus and unclassifed_f Peptococcaceae in the Firmicutes phylum and Hydrogenispora in the Proteobacteria phylum was the key to improving the operation efficiency of SAARB.

[0013] At the same time, the ultraviolet radiation Fenton type (UV / Fe 0 / H2O2) method deep treatment, UV can effectively strengthen Fe 0 / H2O2 system for the removal of organic matter in SAARB effluent, in which the main active oxygen species is HO · UV not only directly photolyzes H2O2 and promotes Fe 0 Release Fe 2+ The two effects form a homogeneous Fenton reaction, which also accelerates the Fe 0 Surface corrosion forms more iron oxides that react with H2O2 to produce HO more quickly. · HO · It can preferentially react with organic matter containing chromogenic groups or auxochrome groups, attack HA and FA containing a large amount of conjugated structures, and then convert them into small molecular organic matter, and even achieve mineralization. 0 Oxidation generates iron oxides which have a certain adsorption capacity and can also remove some organic matter. 0 As a deep treatment method for SAARB effluent, the / H2O2 method can effectively remove a variety of organic matter in the environment, reduce the generation of iron sludge or toxic and harmful by-products, and reduce reagent consumption and treatment costs. It can provide a guarantee for the discharge of landfill leachate in compliance with standards and has broad application prospects.

[0014] Furthermore, the COD of the effluent from the landfill leachate membrane bioreactor is 1000-6000 mg / L, the total nitrogen is 100-1000 mg / L, and the ammonia nitrogen is 0-1000 mg / L.

[0015] Furthermore, in step 1, Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:(4-6); the dosage of Fenton reagent is 50mmol~60mmol per liter of landfill leachate membrane bioreactor effluent. 2+ The added molar ratio of H2O2 and the dosage of Fenton's reagent can better ensure the treatment quality of leachate and achieve the leachate discharge limit.

[0016] In some embodiments, Fe 2+ The solution is ferrous sulfate heptahydrate (FeSO4·7H2O) solution.

[0017] In some embodiments, the Fenton reagent includes Fe 2+ The molar ratio of addition to H2O2 is 1:4, 1:5, 1:6.

[0018] In some embodiments, the dosage of Fenton's reagent per liter of landfill leachate membrane biological process effluent is 50 mmol, 55 mmol, or 60 mmol.

[0019] Furthermore, the Fenton treatment time is 0.5-3h. Reasonable control of the Fenton treatment time can achieve good treatment effects efficiently.

[0020] In some embodiments, the Fenton treatment time is 0.5h, 1h, 2h, or 3h.

[0021] Furthermore, the semi-aerobic mineralized waste bed includes mineralized waste with a compaction density of 850-1000 kg / m 3 . Reasonable compaction density can better meet the water treatment and purification effect.

[0022] In some embodiments, the compacted density of the semi-aerobic mineralized garbage bed is 850 kg / m 3 , 900kg / m 3 , 950kg / m 3 , 1000kg / m 3 .

[0023] Furthermore, the quasi-aerobic mineralized garbage bed is obtained by repeatedly injecting domestic sewage until the effluent COD index fluctuates between 1% and 2%. The specific SAARB operation mode can be found in the disclosure of Example 1 in the specific implementation method of Chinese patent CN 108975552 A.

[0024] Furthermore, during the water treatment process of the semi-aerobic mineralized garbage bed, the hydraulic load is 1-3L / (m 3 d), the water inlet frequency is 1-2 times / d. Reasonable control of hydraulic load and water inlet frequency can better ensure that the purification quality reaches the standard limit.

[0025] Furthermore, in step 3, the power of ultraviolet light irradiation is 8-15 W. Reasonable control of the power of ultraviolet light can better ensure the quality of purification treatment.

[0026] In some embodiments, the power of the ultraviolet light is 8W, 9W, 10W, 11W, 12W, 13W, 14W, or 15W.

[0027] In some embodiments, Fe 0 The particle size is 100nm-500nm. Reasonable control of Fe 0 The particle size of Fe 0 The particle size is 200nm-500nm.

[0028] Further, in step 3, per liter of quasi-aerobic mineralized garbage bed effluent, Fe0 The dosage is 1-3mmol, and the dosage of H2O2 is 10-15mmol. Reasonable control of Fe 0 The dosage of H2O2 can better ensure that the purified water is below the discharge limit.

[0029] In some embodiments, Fe 0 The dosage is 1mmol, 2mmol, and 3mmol.

[0030] In some embodiments, the amount of H2O2 added per liter of effluent from the semi-aerobic mineralized garbage bed is 10 mmol, 11 mmol, 12 mmol, 13 mmol, 14 mmol, or 15 mmol.

[0031] Another object of the present invention is to provide a device for treating landfill leachate.

[0032] The device used in the above-mentioned method for treating landfill leachate comprises a Fenton treatment tank, a semi-aerobic mineralized landfill bed and a photoreactor connected in sequence;

[0033] The Fenton treatment tank is used to receive the landfill leachate for Fenton pretreatment; the semi-aerobic mineralized garbage bed is used to receive the effluent from the Fenton treatment for biological reaction treatment; and the photoreactor is used to receive the effluent from the semi-aerobic mineralized garbage bed for deep oxidation treatment under light.

[0034] The treatment device provided by the present invention comprises a Fenton treatment tank, a semi-aerobic mineralized garbage bed and a photoreactor connected in sequence; the Fenton treatment tank is used to receive garbage leachate for Fenton pretreatment; the semi-aerobic mineralized garbage bed is used to receive Fenton treatment effluent for biological reaction treatment; the photoreactor is used to receive effluent from the semi-aerobic mineralized garbage bed for deep oxidation treatment under light. The treatment device has a simple structure, low cost and is easy to promote.

[0035] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0036] 1. The method for treating the effluent from the membrane bioreactor of landfill leachate provided by the present invention comprises, in sequence, Fenton pretreatment, quasi-aerobic mineralized garbage bed treatment and ultraviolet irradiation Fenton deep treatment. Through the mutual coordination of the three-stage treatment methods and the targeted adjustment of the process parameters, the effluent from the membrane bioreactor of landfill leachate can be purified to below the emission limit standard, achieving good operating results, simple operation, and easy promotion.

[0037] 2. The treatment device provided by the present invention comprises a Fenton treatment tank, a semi-aerobic mineralized garbage bed and a photoreactor connected in sequence; the Fenton treatment tank is used to receive garbage leachate for Fenton treatment; the semi-aerobic mineralized garbage bed is used to receive Fenton treatment effluent for biological reaction treatment; the photoreactor is used to receive effluent from the semi-aerobic mineralized garbage bed for oxidation water treatment under light. The treatment device has a simple structure, low cost and is easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 The following are the water inlet and microbial sampling times of SAARB at each stage in Example 1.

[0039] Figure 2 The data for the removal effect and conversion characteristics of organic matter in the effluent of the landfill leachate MBR under the Fenton system in Example 1; Figure 2 (a) Organic matter removal effect; Figure 2 (b) in the figure is UV-vis; Figure 2 (c) in the figure is 3D-EEM.

[0040] Figure 3 CN and UV in the SAARB effluent in Example 1 254 、COD、NH4 + 、NO3 - , TN and FA concentration changes.

[0041] Figure 4 The ratio of (ab) Fenton reagent, (cd) Fenton reagent dosage and (ef) initial pH value to UV / Fe in Example 1 0 UV of organic matter in H2O2 system 254 and CN removal rate; SAARB effluent was treated with UV / Fe 0 / After H2O2 system treatment (g)SUV 254 , (h) Changes in TOC oxidation capacity and initial removal rate; (i) Suspended solid concentration in mixed liquor (reaction conditions: pH 0 = 3.00, [Fe 2+ ]=[Fe 0 ]=2mM,[H2O2]=12mM,UV power =10W).

[0042] Figure 5 The changes in (a) organic matter, nitrogen pollutants and (b) apparent color of the effluent from the biological treatment of landfill leachate in Example 2 after being treated by different systems.

[0043] Figure 6The diversity indicators of the microbial community alpha in the SAARB before and after the reinjection of Fenton effluent in Example 3 are (a) Ace and Chao, (b) Shannon and Simpson, and (c) Shannoneven and Simpsoneven.

[0044] Figure 7 The microbial community composition of SAARB at the (a) phylum level and (b) genus level in Example 3.

[0045] Figure 8 For example 3 (a) different system HO · The concentration of Fe 0 / H2O2 system and (c)UV / Fe 0 Concentrations of ferrous ions and total iron in the Fe / H2O2 system; 0 (d) SEM spectrum, (e) EDS spectrum, and (f) XRD spectrum before and after the reaction.

[0046] Fig. 9 (ab) UV-Vis, (c) A 226-420 、(d) HA、(e) FA and (f) 3D-EEM changes (reaction conditions: pH0 = 3.00, [Fe 2+ ]=[Fe 0 ]=2mM,[H2O2]=12mM,UV power =10W). DETAILED DESCRIPTION

[0047] The present invention will be described in detail below in conjunction with the accompanying drawings.

[0048] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0049] Example 1

[0050] Three-stage combined treatment effect

[0051] Experimental water sample

[0052] The landfill leachate used in the experiment was taken from the effluent of the membrane bioreactor system (MBR) in a leachate treatment plant supporting a large-scale sanitary landfill in southwest China. The designed treatment capacity is 200m 3 / d. The effluent from the MBR is dark brown and alkaline; the domestic sewage is taken from a sewage well in the residential area of ​​faculty and staff of a certain university, and the water quality is light yellow with a pH value of 7.45. The detailed water quality of the water used in this example is shown in Table 1.

[0053] Table 1 Basic properties of MBR effluent from domestic sewage and landfill leachate

[0054] Water quality indicators Domestic sewage Landfill leachate MBR effluent pH 7.45 7.32 <![CDATA[CN(cm -1 )]]> 0.0634 0.2251 <![CDATA[UV 254 (cm -1 )]]> 0.57 4.3 COD(mg / L) 200 1848 <![CDATA[NH4 + (mg / L)]]> 31.312 2.827 <![CDATA[NO2 - (mg / L)]]> 1.000 4.469 <![CDATA[NO3 - (mg / L)]]> 28.2195 48.2195 TN(mg / L) 60.147 61.7422

[0055] The dilution water used was secondary reverse osmosis ultrapure water (resistivity of 18.25 MΩ·cm) produced by an ultrapure water machine (ULPS-200RO, Sichuan UPU Ultrapure Technology Co., Ltd., China).

[0056] Experimental instruments and equipment

[0057] Fenon enhanced SAARB operation device: The core components include a six-joint agitator and a mineralized garbage bed. The six-joint agitator is provided by Shanghai Shangpu Instrument Equipment Co., Ltd., China, and the model is SN-MS-6D; the mineralized garbage bed is self-built, and the main body is a PVC cylinder with a height of 110cm and a diameter of 30cm. The top is equipped with a leachate inlet and a gas sampling port, and the bottom is equipped with a drainage pipe and a natural ventilation port. The SAARB is filled with about 40kg of mineralized garbage, and the compaction density is about 850kg / m 3 .

[0058] Ultraviolet radiation reaction device: The core components include a heat-collecting digital display magnetic stirrer, a 500mL glass reaction column, an ultraviolet lamp, an external power supply, a magnetic stirrer, a sampling tube, and an external darkroom. The heat-collecting digital display magnetic stirrer is provided by Shenzhen Dingxinyi Experimental Equipment Co., Ltd., China, and the model is DF-101S; the ultraviolet lamp is provided by Heraeus Special Light Co., Ltd., Germany, with a power of 10W and a model of GPH212T5L, which is designed to emit monochromatic ultraviolet light with a wavelength of 254nm, which can meet the lighting conditions required for the experiment in this example.

[0059] Experimental operation

[0060] Before the experiment, NaOH (1M) or H2SO4 (3M) was used to adjust the initial pH value of the MBR effluent to 3.00±0.02, and 100 mL of the adjusted MBR effluent was taken into a 250 mL conical flask and placed under the same six-way stirrer, and then the required amount of Fe 2+ The ratio of Fenton's reagent to H2O2 solution is 1:6, the dosage of Fenton's reagent is 56mM, and the reaction time is 1h. After the reaction is completed, a certain amount of NaOH solution is used to adjust the pH to 9.00±0.02, followed by precipitation, standing, filtering and taking the supernatant.

[0061] Subsequently, in order to improve the biodegradability and treatment efficiency of SAARB, the experiment was divided into three stages: first, the microorganisms in SAARB were acclimated by reinjecting domestic sewage (0-48 days); second, the leachate was directly reinjected into the MBR effluent to enter the operation stage (49-88 days) until the microbial treatment capacity decreased; finally, the MBR effluent was stopped and the effluent after optimized Fenton treatment was reinjected to enter the Fenton enhancement stage (89-123 days). During the entire experiment, the inlet flow rate was maintained at 2L / (m 3 d), water is added once a day and water quality is monitored every two days. Figure 1 .

[0062] Finally, NaOH (1 M) or H2SO4 (3 M) was used to adjust the initial pH value of the SAARB effluent to 3.00 ± 0.02, 400 mL of the adjusted water sample was taken into the reaction container, and the preset amount of Fe 0 and H2O2, and stir with a magnetic stirrer at a speed of 800 rpm. Place the UV lamp in the reaction vessel, and make sure the entire device is in a dark room without light interference, quickly start the UV lamp source and start timing immediately. Take 25mL of water sample at different time points, measure its pH value and adjust it to 9.00±0.02 to remove iron to terminate the reaction. After the water sample is allowed to settle for 10 minutes, it is quickly filtered using a 0.45μm filter membrane, and the filtrate is heated in a water bath (50±2℃) for 30 minutes to remove residual H2O2. After the water sample is cooled to room temperature (20±2℃), the indicators of organic matter and nitrogen pollutants are analyzed.

[0063] Experimental analysis methods

[0064] The pH value of water samples was determined by glass electrode method (DZS-706-A multifunctional parameter meter, Leici, China). The TOC concentration of water samples was determined by TOC analyzer (Multi N / C 3100, Jena, Germany), which can reflect the mineralization degree of organic matter. The COD and TN concentrations in the leachate were determined by microwave digestion method in standard method (CJ / T 428-2013). The NH4 in the leachate was determined by Nessler reagent spectrophotometry, N-(1-naphthyl)-ethylenediamine spectrophotometry and UV spectrophotometry, respectively. + 、NO2 - and NO3 - Concentration. The free ammonia (FA) concentration is calculated using formula 1, where T represents temperature (°C), and its value is based on NH4 + concentration and pH of the sample.

[0065]

[0066] The chromaticity (CN) of the water samples was measured by a UV-Vis-NIR spectrophotometer (Alpha-1502, Shanghai Spectron Instrument Co., Ltd., Shanghai, China), and the absorbance values ​​at wavelengths of 436, 525, and 620 nm (denoted as A 436 , A 525 , A 620 ) to calculate the chromaticity of the water sample (Formula 2). CN can not only represent the color of the landfill leachate sample, but also the relative content of the chromophores of organic matter in the landfill leachate. The ultraviolet absorbance at a wavelength of 254nm (referred to as UV 254 ) to indicate the relative content of humic acid. 254 The ratio of SUV to TOC concentration can be calculated 254 (Formula 3), SUV 254 It is directly proportional to the aromaticity of organic matter.

[0067]

[0068]

[0069] Mixed Liquor Suspended Solids (MLSS) was used to characterize UV / Fe 0 / H2O2 system and Fe 0 The concentration of iron sludge generated in the / H2O2 system is calculated as shown in the following formula (4): Wherein, m is the total mass of iron sludge, mg; V is the volume of the solution, L.

[0070]

[0071] The removal rate (η) is used to reflect the changes in landfill leachate before and after treatment, and the specific calculation is shown in equations (5) and (6). The Behnajady-Modirshahla-Ghanbery kinetic (BMG) model is used to describe the degradation rate of organic matter in landfill leachate.

[0072]

[0073] Where η is the removal rate, %; t is the reaction time, min; c0 and c t Represent the organic matter concentration at the beginning of the water sample reaction and at reaction time t respectively; m and b are two characteristic constants, corresponding to the intercept and slope of the straight line after linear fitting. m is a characteristic constant related to the reaction rate, 1 / m is the initial rate of the reaction, and the larger the 1 / m value, the larger the initial reaction rate. b is a characteristic constant related to the oxidation capacity, 1 / b is the theoretical maximum removal rate of organic matter, which reflects the oxidation capacity of the system.

[0074] Results and Discussion

[0075] Removal effect of organic matter in MBR effluent by Fenton system

[0076] Depend on Figure 2 It can be seen that the removal rate of organic matter in Fenton effluent showed a trend of rapid increase and gradual stability with the increase of Fenton reagent ratio and dosage, and 2+ ]:[H2O2]) is 1:6, and when the dosage reaches 56mM, the UV 254 The removal rates of HO, CN and TOC were stable at 90%, 97.6% and 60.5% respectively. In addition, the 3D-EEM and UV-vis results showed that during the Fenton pretreatment process, · It will react violently with the benzene ring structure of organic matter in the MBR effluent, destroying the benzene ring structure of organic matter and reducing its complexity. · It will also react with humic acid and other difficult-to-degrade organic matter in the MBR effluent, reduce the humification degree of the leachate, and thus improve the biodegradability of the MBR effluent.

[0077] Effect of Fenton pretreatment on the treatment of MBR effluent by SAARB system

[0078] Depend on Figure 3 It can be seen that during the acclimation stage (Stage 1 0-48d), the removal effect of SAARB on pollutants gradually increased and tended to be stable over time. By the 48th day, NH4 + The removal rates of NH4+ and TN reached 99.28% and 76.13% respectively, indicating that the microorganisms in the SAARB have good pollutant degradation performance. After that, the MBR effluent was directly recharged with leachate and entered the operation stage (Stage 2 49-89d). However, long-term direct recharge of MBR effluent with low biodegradability led to the accumulation of pollutants in the SAARB and the decline of treatment performance. In the late operation stage (65-89d), NH4 + 、NO3 - , and TN concentrations increased. The microorganisms in SAARB need organic carbon sources as electron donors to carry out ammonia oxidation and denitrification processes to degrade nitrogen pollutants, but the refractory organic matter in the MBR effluent limits this process. At the same time, high salt accumulation also affects the removal effect of SAARB, which ultimately leads to a decline in the operation of SAARB and instability.

[0079] In order to improve the operation of SAARB, the landfill leachate MBR effluent was subjected to Fenton pre-oxidation, and the Fenton effluent was circulated to SAARB to enter the Fenton enhancement stage (Stage 3 89-123d). The results showed that after the Fenton effluent was reinjected, the removal effect of organic matter was rapidly improved, and the concentration of organic matter in the effluent was greatly reduced (COD concentration was reduced by 60%). In addition, the reinjection of Fenton effluent improved the removal effect of SAARB on nitrogen. Compared with 89d, the NH4 + 、NO3 - and TN concentrations decreased by 66%, 50%, and 50%, respectively. In addition, the removal efficiency of FA by SAARB was also greatly improved. After 110 days, the removal rate of FA in the effluent was stabilized at more than 95%, indicating that reinjection of Fenton effluent can effectively alleviate the inhibitory effect of SAARB on denitrifying bacteria.

[0080] UV combined with Fe 0 Treatment effect of / H2O2 system on SAARB effluent

[0081] After Fenton combined with SAARB system treatment, nitrogen pollutants in the landfill leachate were reduced, but the organic matter concentration remained at a high level, and compared with the original landfill leachate, the SAARB effluent contained more long carbon chain difficult to biodegrade organic matter. 0 / H2O2 system was used to deeply treat the effluent from SAARB to ensure the safety of the water environment. The effects of Fenton reagent ratio, dosage and initial pH value on the treatment effect were investigated by testing organic matter indicators, and the UV / Fe 0 / H2O2 system treatment effect.

[0082] from Figure 4 From (a) to (f), we can see that in UV / Fe 0 In the / H2O2 system, increasing the proportion and dosage of Fenton reagent can improve the removal rate of organic matter. 0 The increase in the concentration of Fe 2+ and the formation of iron oxides, accelerating the activation of H2O2, thereby producing more HO · When the Fenton reagent ratio was 1:6, the dosage increased from 3.5mM to 14mM. After 60min of reaction, UV 254 and CN removal rates increased by 17.24% and 23.56%, respectively. 0 The removal rate of organic matter in the / H2O2 system decreased. This is because the increase in pH value will cause H2O2 to decompose ineffectively, which directly affects the Fe 3+and Fe 2+ The complexation equilibrium of Fe 3+ / Fe 2+ The redox cycle is blocked, reducing HO · production, thereby reducing the removal effect of organic matter.

[0083] On this basis, the UV / Fe 0 / H2O2 system for the removal of organic matter, and compared the UV / H2O2, Fe 0 / H2O2、Fe 2+ / H2O2 and UV / Fe 2+ / H2O2 system. Figure 4 (g)-(i) shows that UV / Fe 0 The / H2O2 system was significantly better than other systems in removing organic matter from SAARB effluent. 254 From 2.64 to 1.10. The BMG model can well fit the CN and UV in the treated effluent 254 and TOC concentration changes over time, the determination coefficient (R 2 ) are all above 0.9. The addition of UV does not increase the Fe 0 The removal rate and oxidation capacity of the UV / Fe system also reduced the generation of secondary pollutants, iron sludge, from 264 mg / L to 190 mg / L. 0 / H2O2 system can effectively remove organic matter from SAARB effluent, reduce treatment costs and promote the recovery and utilization of iron.

[0084] Example 2

[0085] The water quality and discharge compliance of the effluent during the three-stage combined treatment process in Example 1 are shown in Table 2.

[0086] Table 2 Water quality of landfill leachate membrane bioreactor after treatment by different methods

[0087]

[0088] Note: 1 Refer to the emission limits of water pollutants directly discharged in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0089] In the process of using SAARB to treat landfill leachate, microorganisms are the key to removing organic and nitrogen pollutants, but it is difficult for microorganisms to use polycyclic and other difficult-to-degrade organic matter in landfill leachate as a carbon source. In other words, the lack of effective carbon sources in landfill leachate limits the treatment effect of SAARB. Here, the difficult-to-degrade organic matter in landfill leachate is converted into substances that are easily bioavailable through Fenton pre-oxidation, and then the effluent is re-injected into SAARB to improve its operation effect. The results are as follows Figure 5 shown.

[0090] In the Fenton pre-oxidation stage, the COD concentration of the landfill leachate dropped from 2248 mg / L to 552 mg / L, and the COD removal rate was as high as 75.44%. + -N、NO3 - -N and TN removal rates were only 47.05%, 21.28% and 17.40%, respectively. This indicates that the Fenton system can effectively reduce organic matter in landfill leachate, but has limited removal effects on nitrogen pollutants. After the Fenton pre-oxidation effluent was reinjected into the SAARB, it was found that the removal effects of organic matter and nitrogen pollutants were improved, especially nitrogen pollutants. Compared with the Fenton pre-oxidation effluent, the COD and NH4 + 、NO3 - and TN concentrations decreased to 468, 0.222, 16.69, and 24.22 mg / L, respectively.

[0091] Although the nitrogen pollutant concentration in the landfill leachate after treatment by the Fenton combined SAARB system can reach the direct discharge leachate standard of China's "Landfill Pollution Control Standard" (GB 16889-2024), the organic matter concentration, such as COD concentration, still far exceeds the limit of 100 mg / L. 0 / H2O2 method deep treatment of SAARB effluent, found that the final effluent COD, NH4 + and TN concentrations were reduced to 89, 0.151, and 16.39 mg / L, respectively, meeting the direct discharge limits of water pollutants, confirming the effectiveness of the engineering application of this process.

[0092] Compared with biological or advanced oxidation methods alone to treat landfill leachate, combining them to treat landfill leachate has better results, and the order and position of the combined process play a key role. Especially when using advanced oxidation methods to treat landfill leachate, the concentration of organic matter is too high, and the oxidant will inevitably be used in large doses, resulting in a significant increase in treatment costs, and a large number of toxic and harmful by-products will be formed, bringing new water environmental risks. In this study, the Fenton enhanced SAARB method was used as the first step of the process, which can reduce the concentration of organic and nitrogen pollutants, reduce the removal load of the subsequent advanced oxidation method, and avoid reducing the subsequent UV irradiation efficiency due to the darker apparent color of the landfill leachate; the UV / Fe 0 As a deep treatment method of combined process, Fenton enhanced SAARB combined with UV / Fe 0 The / H2O2 process can reduce the risk of toxic and harmful byproducts, reagent consumption and treatment costs while ensuring the treatment effect. It should be noted that due to the complex and variable water quality and quantity of landfill leachate, most of them need to adopt targeted treatment processes according to specific conditions and economic and technical requirements. This study provides a feasible solution for the discharge of landfill leachate in compliance with standards.

[0093] Example 3

[0094] Three-stage combined treatment mechanism (Fenton pretreatment + SAARB treatment + UV Fenton-like deep treatment)

[0095] Experimental water

[0096] The experimental water includes MBR effluent and domestic sewage. The detailed water quality characteristics are shown in Table 1.

[0097] This example studies the removal mechanism of organic matter in the effluent of landfill leachate MBR in a three-stage combined treatment system.

[0098] Experimental setup

[0099] The mineralized garbage bed used in this example is a PVC cylinder with a height of 110 cm and a diameter of 30 cm. The top is provided with a leachate inlet and a gas sampling port, and the bottom is provided with a drainage pipe and a natural ventilation port. The SAARB is filled with about 40 kg of mineralized garbage, and the compacted density is about 850 kg / m 3 .

[0100] Experimental analysis methods

[0101] In this example, the "acclimatization-operation-Fenton strengthening" of the SAARB is divided into three stages. The first is the acclimatization stage of the mineralized garbage bed (0-48 days); the second is the operation stage (49-88 days); and the last is the Fenton strengthening stage (89-123 days). At the end of the operation stage and the Fenton strengthening stage, the mineralized garbage in the SAARB is sampled and marked as MBR_1 to MBR_5 and Fenton_1 to Fenton_5. The specific sampling time is shown in Figure 1 . A total of 10 samples were obtained at the 77th, 78th, 79th, 82nd, 86th, 95th, 102nd, 109th, 116th and 123rd days. The samples were sequenced using the Illumina platform. After PCR amplification with primers, the 16S_rRNA sequence of the total bacteria was determined. The primers for the V3-V4 region of the detection area were 338F (5'-ACTCCTACGGGAGGCAGCAG-3') and 806R (5'-GGACTACHVGGGTWTCTAAT-3'). The sequencing platform was Illumina MiSeq.

[0102] The absorbance of water samples was scanned in the wavelength range of 200-600 nm using a UV-visible-near infrared spectrophotometer (Alpha-1502, Shanghai Spectron Instrument Co., Ltd., Shanghai, China), with a scanning interval of 1 nm. The Fe 2+ The relative content of fluorescent dissolved organic matter in the landfill leachate samples was determined by a three-dimensional fluorescence spectrometer (Aqualog-UV-800C, Horiba Scientific Japan), with fixed excitation wavelength (Ex) and emission wavelength (Em) of 200-550 nm, scanning interval of 5 nm, and scanning speed of 2400 nm / min.

[0103] The pH value of water samples was determined by glass electrode method (DZS-706-A multifunctional parameter analyzer, Leici, China). Organic matter was determined by high performance liquid chromatography (LC-2050, Shimadzu, Japan) with UV detector and equipped with 4.6 mm × 25 cm, 5 μm C18 column (TSKgel ODS-100V, Tosoh, Japan).

[0104] Scanning electron microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to analyze the Fe 0 Among them, scanning electron microscopy combined with X-ray spectrometer (JSM-5900LV, JEOL Ltd., Japan) can be used to characterize Fe0 The elemental composition, morphology and structure of the surface before and after the reaction were observed and analyzed; X-ray diffractometer (MiniFlex600, Rigaku Corporation, Japan) was used to analyze the Fe 0 The crystal structures before and after the reaction were analyzed.

[0105] Results and Discussion

[0106] Mechanisms of changes in microbial communities in SAARB by Fenton pretreatment

[0107] The length of 16S rRNA sequencing was 878120. Through the comparison of Silva 138 / 16s_bacteria database at 97% confidence level, a total of 59814 operational taxonomic units (OUT) were obtained from 10 mineralized garbage samples. The sequencing coverage of all samples exceeded 99%, which well reflected the actual situation of the samples at this sequencing depth.

[0108] The changes in alpha diversity of the microbial community in the SAARB before and after the reinjection of Fenton effluent are shown in Figure 6 . At the end of the operation stage (77d-86d), the Simpson index and Simpsoneven index of microorganisms in SAARB increased, while the Shannon index and Shannoneven index decreased, and the microbial diversity and uniformity decreased. This shows that long-term reinjection of low-biodegradable leachate MBR effluent has worsened the living environment of microorganisms in SAARB, thereby affecting the microbial diversity and uniformity. However, Fenton pre-oxidation significantly reduced the concentration of difficult-to-degrade organic matter in MBR effluent, and the alpha diversity of microorganisms was significantly improved. The Ace index, Chao index, Shannon index, Shannoneven index and Simpsoneven index were all greater than those at the end of the operation stage. This shows that after reinjection of Fenton effluent, the growth, metabolism and reproduction activities of microorganisms are more intense, the species diversity and uniformity are improved, the adaptability of microorganisms to harsh environments is improved, and the degradation effect of SAARB on pollutants is improved.

[0109] like Figure 7As shown in the figure, the changes in the composition of the microbial community (16S_bacteria) at the phylum and genus levels in SAARB before and after the reinjection of Fenton effluent were analyzed. The study found that 86 days before the reinjection of Fenton effluent (MBR-5), the proportion of each bacterial genera that played an important role in the degradation of pollutants in SAARB was relatively uniform, and the top five dominant bacterial phyla were Proteobacteria (23.52%~36.81%), Firmicutes (24.09%~27.94%), Chloroflexi (9.21%~16.019%), Acidobacteriota (7.25%~8.51%) and Actinobacteriota (6.24%~13.39%). At the end of the operation stage, the relative proportion of bacterial phyla in SAARB changed, and the abundance of key bacterial genera decreased, resulting in a decrease in the treatment effect of SAARB. In the Fenton enhanced stage, the relative abundance of Proteobacteria, Firmicutes and Actinobacteriota, which play a key role in the removal of pollutants in the mineralized garbage bed, increased from 28.95%, 23.91% and 6.57% to 29.11%, 25.93% and 7.73%, respectively. With the increase of reinjection time, the dominant bacterial species continued to be enriched, and the proportion of dominant bacterial genera that had a degrading effect on nitrogen pollutants and organic matter increased significantly, thus restoring the removal effect of SAARB on pollutants.

[0110] UV / Fe 0 Degradation mechanism of organic matter by H2O2 system

[0111] Usually, HO · As the dominant reactive oxygen species in heterogeneous Fenton-like systems, it has an important influence on the degradation of organic matter in SAARB effluent. 0 HO in the H2O2 system · , quantitatively analyzed the HO generated in the system · The production situation. Figure 8 As shown in (a), at 60 min of reaction, HO · In UV / H2O2, Fe 0 / H2O2、UV / Fe 0 / H2O2 system were 0.091, 0.085 and 0.135 mM respectively, UV / Fe 0 HO generated in the H2O2 system · The most and higher than other oxidation systems. It can be seen that UV can not only photolyze H2O2 to produce HO · , and can also promote Fe 0 / H2O2 system reacts to generate more HO· .

[0112] UV-enhanced Fe 0 In the H2O2 system, HO · The production pathway of Fe 0 Released Fe 2+ It is closely related to its solid phase composition. Figure 8 In the experiments (b)-(c), it was observed that with the increase of reaction time, although Fe 0 / H2O2 system and UV / Fe 0 / H2O2 system showed a trend of gradual increase in total iron concentration, but Fe 2+ There are obvious differences in the changes in concentration. 0 In the / H2O2 system, Fe 0 Dissolved Fe 2+ Almost unchanged; in UV / Fe 0 Fe / H2O2 system 2+ The concentration increased significantly, and UV / Fe 0 Removal of Fe in H2O2 System 2+ Other soluble iron concentrations, including Fe 3+ , significantly lower than Fe 0 / H2O2 system. Through SEM-EDS and XRD analysis ( Figure 8 (d)-(f)), it is found that after the reaction, Fe 0 The surface becomes rough, a new oxidation structure is formed, and UV can enhance the Fe 0 The presence of UV promotes the oxidation of Fe 2+ / Fe 3+ cycle, increasing Fe 2+ ratio, and more iron oxides are generated, providing more active sites for the Fenton reaction, thereby producing more Fe 2+ and HO · .

[0113] UV-Vis and 3D-EEM spectroscopy were used to characterize HO · UV / Fe 0 The degradation law of organic matter in the effluent after treatment with the / H2O2 system was analyzed and compared with the Fe 0 / H2O2 system, the results are as follows Fig. 9 The SAARB effluent shows a smooth spectral response in the UV-Vis spectrum. 226-420The value is as high as 7.54, indicating that its organic matter is highly aromatic and complex in type. 3D-EEM analysis shows that the SAARB effluent contains two fluorescent components: Peak A (humic acid HA, fluorescence intensity 1345.72 au, Ex / Em = 250 / 430 nm), which is mainly low molecular weight, high fluorescence frequency organic matter; Peak C (fulvic acid FA, fluorescence intensity 1198.65 au, Ex / Em = 330 / 420 nm), which is mainly high molecular weight, multi-functional aromatic organic matter. 0 / H2O2, UV / Fe 0 / H2O2 system treated water absorbance, A 226-420 The fluorescence intensity of Peak A and Peak C decreased more significantly, the HA and FA contents decreased significantly, and the fluorescence peaks shifted to the blue. The removal rates reached 62.30% and 51.99% respectively after only 5 min of reaction. 0 / H2O2 system can more effectively destroy the functional groups and aromatic structures of organic matter and degrade humus.

[0114] Therefore, UV-strengthened Fe 0 In the H2O2 system, UV can not only directly photolyze H2O2 and promote Fe 0 Release Fe 2+ The two effects form a homogeneous Fenton reaction, which also accelerates the Fe 0 Surface corrosion forms more iron oxides (such as Fe2O3) which react with H2O2 in a heterogeneous Fenton reaction, thereby producing HO more quickly. · Organic compounds containing chromophores are preferentially oxidized by HO · Attack, then HA and FA, eventually being degraded into small molecules or mineralized.

[0115] In summary, reinjection of Fenton effluent alleviated the instability of SAARB operation, promoted the enrichment of dominant bacteria that have a degradation effect on nitrogen pollutants and organic matter, and significantly improved the removal effect of SAARB on MBR effluent. In particular, the enrichment of functional microorganisms Syntrophaceticus and unclassifed_f Peptococcaceae in the Firmicutes phylum and Hydrogenispora in the Proteobacteria phylum was crucial to improving the operation efficiency of SAARB. 0 When the SAARB effluent is deeply treated by the / H2O2 system, UV can not only directly photolyze H2O2 and promote Fe 0 Release Fe 2+ The homogeneous Fenton reaction is formed, which also accelerates the Fe 0Surface corrosion forms more iron oxides, which react with H2O2 to produce HO in a heterogeneous Fenton reaction. · HO · It preferentially reacts with organic matter containing chromophores, attacks HA and FA containing conjugated structures, converts them into small molecules, and even achieves mineralization. 0 The generated iron oxides can also adsorb and remove some organic matter.

[0116] The method for treating landfill leachate provided by the present invention comprises Fenton pretreatment, quasi-aerobic mineralized landfill bed treatment and UV / Fe 0 / H2O2 method deep treatment, through the mutual coordination of three-stage treatment methods and targeted adjustment of process parameters, can purify the landfill leachate to below the emission limit standard, has achieved good operating results, is simple to operate, and is easy to promote.

[0117] Example 4

[0118] Prepare a quasi-aerobic mineralized garbage bed: The mineralized garbage bed is a PVC cylinder with a height of 110 cm and a diameter of 30 cm. The top is equipped with a leachate inlet and a gas sampling port, and the bottom is equipped with a drainage pipe and a natural ventilation port. The SAARB is filled with about 40 kg of mineralized garbage, and the compaction density is about 850 kg / m 3 The quasi-aerobic mineralized garbage bed is obtained by repeatedly reinjecting domestic sewage until the effluent COD index fluctuates between 1% and 2%.

[0119] Example 4 provides a treatment device, including a Fenton treatment tank, a quasi-aerobic mineralized garbage bed and a photoreactor connected in sequence; the Fenton treatment tank is used to receive leachate for Fenton treatment; the quasi-aerobic mineralized garbage bed is used to receive Fenton treatment effluent for biological reaction treatment; the photoreactor is used to receive effluent from the quasi-aerobic mineralized garbage bed for oxidation water treatment under light.

[0120] The wastewater from the membrane biological method of the leachate produced by a waste treatment plant (COD is 5987 mg / L, total nitrogen is 1960.7 mg / L, and ammonia nitrogen is 1985.6 mg / L) is treated for sewage. The specific treatment process is as follows:

[0121] Step 1: Adjust the initial pH of the effluent from the landfill leachate membrane bioreactor to 3, add Fenton reagent, and perform Fenton treatment for 2 hours; Fenton reagent includes Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:6; the dosage of Fenton reagent in each liter of landfill leachate membrane bioreactor effluent is 50 mmol.

[0122] Step 2: Adjust the pH of the Fenton treated water to 7, filter the sediment, and re-inject it into the semi-aerobic mineralized garbage bed for water treatment; during re-injection, the hydraulic load is 2L / (m3 d), the water inlet frequency is once per day.

[0123] Step 3: Adjust the pH of the effluent from the semi-aerobic mineralized garbage bed to 3, add Fe 0 React with H2O2, Fe 0 The dosage is 2 mmol, the dosage of H2O2 is 12 mmol, the pH of the treated water is adjusted to 7, the precipitate is filtered, and purified water is obtained.

[0124] The purified water was tested for water quality using the test method of Example 1, and the test results are as follows:

[0125] The COD is 97 mg / L, the total nitrogen is 38.64 mg / L, and the ammonia nitrogen is 23.73 mg / L; it has met the direct discharge water pollutant emission standards in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0126] Example 5

[0127] Prepare a quasi-aerobic mineralized garbage bed: The mineralized garbage bed is a PVC cylinder with a height of 110 cm and a diameter of 30 cm. The top is equipped with a leachate inlet and a gas sampling port, and the bottom is equipped with a drainage pipe and a natural ventilation port. The SAARB is filled with about 40 kg of mineralized garbage, and the compaction density is about 1000 kg / m 3 The quasi-aerobic mineralized garbage bed is obtained by repeatedly reinjecting domestic sewage until the effluent COD index fluctuates between 1% and 2%.

[0128] The wastewater from the membrane biological process of the leachate produced by a waste treatment plant (COD is 2035 mg / L, total nitrogen is 113.5 mg / L, and ammonia nitrogen is 82.4 mg / L) is treated for sewage. The specific treatment process is as follows:

[0129] Step 1: Adjust the initial pH of the effluent from the landfill leachate membrane bioreactor to 4, add Fenton reagent, and perform Fenton treatment for 0.5 h; Fenton reagent includes Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:4; the dosage of Fenton reagent in each liter of landfill leachate membrane bioreactor effluent is 60mmol.

[0130] Step 2: The pH of the Fenton treated water was adjusted to 8, precipitated and filtered, and then re-injected into the semi-aerobic mineralized garbage bed for water treatment; during re-injection, the hydraulic load was 1 L / (m 3 d), the water inlet frequency is 2 times / d.

[0131] Step 3: Adjust the pH of the effluent from the semi-aerobic mineralized garbage bed to 4, add Fe 0React with H2O2, Fe 0 The dosage is 1 mmol, the dosage of H2O2 is 10 mmol, the pH of the treated water is adjusted to 8, the precipitate is filtered, and purified water is obtained.

[0132] The purified water was tested for water quality using the test method of Example 1, and the test results are as follows:

[0133] The COD is 65 mg / L, the total nitrogen is 12.34 mg / L, and the ammonia nitrogen is 7.22 mg / L; it has met the direct discharge water pollutant emission standards in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0134] Example 6

[0135] Prepare a quasi-aerobic mineralized garbage bed: The mineralized garbage bed is a PVC cylinder with a height of 110 cm and a diameter of 30 cm. It is equipped with a leachate inlet and a gas sampling port on the top, and a drainage pipe and a natural ventilation port at the bottom. The SAARB is filled with about 40 kg of mineralized garbage, and the compaction density is about 900 kg / m 3 The quasi-aerobic mineralized garbage bed is obtained by repeatedly reinjecting domestic sewage until the effluent COD index fluctuates between 1% and 2%.

[0136] The wastewater from the membrane biological method of the leachate produced by a waste treatment plant (COD is 2643 mg / L, total nitrogen is 163.7 mg / L, and ammonia nitrogen is 128.5 mg / L) is treated for sewage. The specific treatment process is as follows:

[0137] Step 1: Adjust the initial pH of the effluent from the landfill leachate membrane bioreactor to 5, add Fenton reagent, and perform Fenton treatment for 3 hours; Fenton reagent includes Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:8; the dosage of Fenton reagent in each liter of landfill leachate membrane biological process effluent is 40mmol.

[0138] Step 2: Adjust the pH of the Fenton treated water to 9, filter the sediment, and re-inject it into the semi-aerobic mineralized garbage bed for water treatment; during re-injection, the hydraulic load is 3L / (m 3 d), the water inlet frequency is once per day.

[0139] Step 3: Adjust the pH of the effluent from the semi-aerobic mineralized garbage bed to 5, add Fe 0 React with H2O2, Fe 0 The dosage is 3 mmol, the dosage of H2O2 is 20 mmol, the pH of the treated water is adjusted to 8, the precipitate is filtered, and purified water is obtained.

[0140] The purified water was tested for water quality using the test method of Example 1, and the test results are as follows:

[0141] The COD is 82 mg / L, the total nitrogen is 15.33 mg / L, and the ammonia nitrogen is 10.44 mg / L; it has met the direct discharge water pollutant emission standards in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0142] Comparative Example 1

[0143] Comparative Example 1 uses the same quasi-aerobic mineralized garbage bed and landfill leachate membrane biological process effluent as Example 4. The difference from Example 4 is that the treatment process provided in Comparative Example 1 adjusts the Fe 2+ The molar ratio of addition to H2O2 is 1:2, and the other processes are exactly the same as in Example 4.

[0144] After testing, the effluent after purification in Comparative Example 1 had a COD of 131 mg / L, a total nitrogen of 52.41 mg / L, and an ammonia nitrogen of 26.34 mg / L; it did not meet the direct discharge water pollutant emission standards in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0145] Comparative Example 2

[0146] Comparative Example 2 uses the same quasi-aerobic mineralized garbage bed and landfill leachate membrane biological process effluent as Example 4. The difference from Example 4 is that the treatment process provided in Comparative Example 2 adjusts the Fe content per liter of quasi-aerobic mineralized garbage bed effluent in step 3. 0 The dosage was 5 mmol, the dosage of H2O2 was 9 mmol, and the other processes were exactly the same as in Example 4.

[0147] After testing, the effluent after purification in Comparative Example 2 had a COD of 105 mg / L, a total nitrogen of 56.12 mg / L, and an ammonia nitrogen of 28.44 mg / L; it did not meet the direct discharge water pollutant emission standards in China's "Pollution Control Standards for Municipal Solid Waste Landfills" (GB 16889-2024).

[0148] In some embodiments, the COD of the landfill leachate is 1000-6000 mg / L, the total nitrogen is 100-1000 mg / L, and the ammonia nitrogen is 0-1000 mg / L.

[0149] Furthermore, in step 1, Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:(4-6); the dosage of Fenton reagent is 50mmol~60mmol per liter of landfill leachate membrane bioreactor effluent. 2+The added molar ratio of H2O2 and the dosage of Fenton's reagent can better ensure the treatment quality of leachate and achieve the leachate discharge limit.

[0150] In some embodiments, Fe 2+ The solution is ferrous sulfate heptahydrate (FeSO4·7H2O) solution.

[0151] In some embodiments, the Fenton reagent includes Fe 2+ The molar ratio of addition to H2O2 is 1:4, 1:5, 1:6.

[0152] In some embodiments, the dosage of Fenton's reagent per liter of landfill leachate membrane biological process effluent is 50 mmol, 55 mmol, or 60 mmol.

[0153] Furthermore, the Fenton treatment time is 0.5-3h. Reasonable control of the Fenton treatment time can achieve good treatment effects efficiently.

[0154] In some embodiments, the Fenton treatment time is 0.5h, 1h, 2h, or 3h.

[0155] Furthermore, the semi-aerobic mineralized waste bed includes mineralized waste with a compaction density of 850-1000 kg / m 3 . Reasonable compaction density can better meet the water treatment and purification effect.

[0156] In some embodiments, the compacted density of the semi-aerobic mineralized garbage bed is 850 kg / m 3 , 900kg / m 3 , 950kg / m 3 , 1000kg / m 3 .

[0157] Furthermore, the quasi-aerobic mineralized garbage bed is obtained by repeatedly injecting domestic sewage until the effluent COD index fluctuates between 1% and 2%. The specific operation mode of SAARB can be found in the disclosure of Chinese patent CN 108975552 A.

[0158] Furthermore, during the water treatment process of the semi-aerobic mineralized garbage bed, the hydraulic load is 1-3L / (m 3 d), the water inlet frequency is 1-2 times / d. Reasonable control of hydraulic load and water inlet frequency can better ensure that the purification quality reaches the standard limit.

[0159] Furthermore, in step 3, the power of ultraviolet light irradiation is 8-15 W. Reasonable control of the power of ultraviolet light can better ensure the quality of purification treatment.

[0160] In some embodiments, the power of the ultraviolet light is 8W, 9W, 10W, 11W, 12W, 13W, 14W, or 15W.

[0161] In some embodiments, Fe 0 The particle size is 100nm-500nm. Reasonable control of Fe 0 The particle size of Fe 0 The particle size is 200nm-500nm.

[0162] Further, in step 3, per liter of quasi-aerobic mineralized garbage bed effluent, Fe 0 The dosage is 1-3mmol, and the dosage of H2O2 is 10-15mmol. Reasonable control of Fe 0 The dosage of H2O2 can better ensure that the purified water is below the discharge limit.

[0163] In some embodiments, Fe 0 The dosage is 1mmol, 2mmol, and 3mmol.

[0164] In some embodiments, the amount of H2O2 added per liter of effluent from the semi-aerobic mineralized garbage bed is 10 mmol, 11 mmol, 12 mmol, 13 mmol, 14 mmol, or 15 mmol.

[0165] The method for treating the effluent from the membrane bioreactor of landfill leachate provided by the present invention comprises, in sequence, Fenton pretreatment, quasi-aerobic mineralized garbage bed treatment and ultraviolet irradiation Fenton deep treatment. Through the mutual coordination of the three-stage treatment methods and the targeted adjustment of the process parameters, the effluent from the membrane bioreactor of landfill leachate can be purified to below the emission limit standard, and good operating effect has been achieved. The operation is simple and easy to promote. Through a large number of experimental explorations, it has been found that if the order of the three-stage treatment methods is adjusted or the process parameters are adjusted outside a reasonable range, the effect of failing to reach the emission limit standard will occur.

[0166] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for treating effluent from a landfill leachate membrane bioreactor, characterized in that: The following steps are involved: Step 1: Adjust the initial pH of the effluent from the landfill leachate membrane bioreactor to 3-5, and add Fe 2+ solution and H2O2, and then treated by Fenton method; among them, Fe 2+ The molar ratio of the addition of Fenton reagent to H2O2 is 1:(4-8); the dosage of Fenton reagent per liter of landfill leachate membrane bioreactor effluent is 40mmol~60mmol; Step 2: adjusting the pH of the effluent from the Fenton process to 7-9, filtering the effluent through sedimentation, and recharging the effluent into the semi-aerobic mineralized garbage bed for water treatment; Step 3: Adjust the pH of the effluent from the semi-aerobic mineralized garbage bed to 3-5, add Fe 0 and H2O2 to adjust the pH of the treated water to 7-9, precipitate and filter to obtain purified water; wherein, the power of ultraviolet light irradiation is 6-20W; per liter of quasi-aerobic mineralized garbage bed effluent, Fe 0 The dosage is 1-3 mmol, and the dosage of H2O2 is 10-20 mmol.

2. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 1, characterized in that: The COD of the effluent from the landfill leachate membrane bioreactor is 1000-6000 mg / L, the total nitrogen is 100-1000 mg / L, and the ammonia nitrogen is 0-1000 mg / L.

3. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 1, characterized in that: In step 1, Fe 2+ The molar ratio of Fenton reagent to H2O2 is 1:(4-6); the dosage of Fenton reagent in the effluent of the membrane bioreactor of landfill leachate is 50mmol-60mmol.

4. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 3, characterized in that: The Fenton treatment time is 0.5-3h.

5. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 1, characterized in that: The semi-aerobic mineralized garbage bed consists of mineralized garbage with a compaction density of 850-1000kg / m 3 .

6. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 5, characterized in that: During the water treatment process of the semi-aerobic mineralized garbage bed, the hydraulic load is 1-3L / (m 3 d), the water inlet frequency is 1-2 times / d.

7. The method for treating effluent from a landfill leachate membrane bioreactor according to any one of claims 1 to 6, characterized in that: In step 3, the power of ultraviolet light irradiation is 8-15W.

8. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 7, characterized in that: Fe 0 The particle size is 100nm-500nm.

9. The method for treating effluent from a landfill leachate membrane bioreactor according to claim 7, characterized in that: In step 3, Fe 0 The dosage is 1-3 mmol, and the dosage of H2O2 is 10-15 mmol.

10. The treatment device used in the method for treating effluent from a landfill leachate membrane bioreactor according to any one of claims 1 to 9, characterized in that: It includes a Fenton treatment tank, a semi-aerobic mineralized garbage bed and a photoreactor connected in sequence; The Fenton treatment tank is used to receive the effluent from the landfill leachate membrane bioreactor for Fenton treatment; the semi-aerobic mineralized garbage bed is used to receive the effluent from the Fenton treatment for biological reaction treatment; and the photoreactor is used to receive the effluent from the semi-aerobic mineralized garbage bed for oxidation water treatment under light.

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