Full-quantitative treatment process for landfill leachate

Abstract

The invention discloses a full-quantitative treatment process for landfill leachate, and relates to the technical field of leachate treatment. According to the invention, sodium carboxymethyl starch is used as a skeleton, acrylamide and modified vinylpyridine which is quaternized by 5-chloromethyl salicylaldehyde are grafted, secondary crosslinking is carried out, and then thiosemicarbazide is used for grafting modification, so that the modified vinylpyridine is obtained. The adsorbent has high salt tolerance and heavy metal chelating capacity, can efficiently adsorb heavy metals in a high-salt environment, can reinforce nitrate removal through the synergistic effect of pyridyl enrichment and nitrification inhibition after adsorption, realizes synchronous treatment of organic matters, ammonia nitrogen, heavy metals and nitrate in leachate, and is simple in process and environment-friendly.

Description

Technical Field

[0001] The invention relates to the technical field of leachate treatment, in particular to a fully quantitative treatment process for landfill leachate. Background Art

[0002] The current leachate quality from landfills has the following characteristics: 1. Complex pollutant composition and significant fluctuations in water quality. Due to the complex composition of the waste, the leachate contains complex pollutants. Leachate pollutants include organic matter, inorganic ions, and nutrients. Principal among these are ammonia nitrogen, various dissolved cations, heavy metals, phenols, soluble fatty acids, and other organic pollutants. 2. High organic matter concentration. BOD and COD concentrations in leachate can reach tens of thousands of mg / L, but these gradually decrease with landfill age. Even so, they still reach several thousand mg / L, which is still relatively high compared to other wastewaters. The leachate also contains significant amounts of humic acid. 3. High ammonia nitrogen concentration. Ammonia nitrogen concentration increases with landfill age, and most nitrogen in the leachate exists in the form of ammonia nitrogen. The ammonia nitrogen concentration in leachate increases with the number of years the landfill has been in operation. 4. High concentrations of heavy metal ions and salt content. When domestic waste is landfilled alone, the heavy metal content is low; however, when mixed with industrial waste or sludge, the heavy metal content and salt content are very high. Biochemical treatment will inhibit and toxic the biochemical process due to the high salt content, resulting in startup difficulties, unstable operation, or even inoperability.

[0003] Therefore, this application adopts modified denitrification resin for treatment and designs a matching process flow, in which the modified denitrification resin has high salt tolerance and the ability to chelate and adsorb heavy metal ions, and after chelating and adsorbing heavy metal ions, it can also promote the removal of nitrates to enhance the denitrification treatment capacity. Summary of the Invention

[0004] The purpose of the present invention is to provide a fully quantitative treatment process for landfill leachate to solve the problems existing in the prior art.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions: A fully quantitative treatment process for landfill leachate comprises the following steps: Pretreatment in the regulating tank: leachate is introduced into the regulating tank, water quality and quantity are adjusted by the water inlet pump, and the water level is monitored in real time using a liquid level meter; Combined treatment in biochemical pool: After pre-treatment in the regulating pool, the water enters the biochemical pool, where it is treated and degraded by an aeration fan, and combined with a reflux system to achieve biological nitrogen and phosphorus removal; SMT-DT high-efficiency catalytic oxidation deep treatment: The effluent from the biochemical pool passes through the SMT-DT high-efficiency catalytic oxidation module, which uses an external electric field to generate a magnetic field for two-phase catalytic oxidation; Integrated special-effect bacteria MBR system: The effluent from SMT-DT catalytic oxidation treatment is separated by the MBR membrane system. The water production pump improves the water quality. The backwash pump regularly maintains the membrane components. An integrated high-efficiency bacteria biological denitrification module is connected and halophilic denitrifying bacteria are added to promote denitrification. After denitrification, the wastewater enters the secondary MBR membrane, where ammonia nitrogen and carbon sources are further removed by controlling the residence time. Denitrification resin treatment: The final effluent passes through the denitrification resin tank, filled with modified denitrification resin to adsorb residual nitrates to achieve standard discharge; The modified denitrification resin comprises: sodium carboxymethyl starch, acrylamide and modified vinyl pyridine; The modified denitrification resin is prepared by grafting acrylamide and modified vinyl pyridine onto sodium carboxymethyl starch using sodium carboxymethyl starch, acrylamide and modified vinyl pyridine through reverse suspension polymerization, and then grafting and modifying the resin using thiosemicarbazide after secondary cross-linking and curing.

[0006] As an optimization, the modified vinyl pyridine is prepared by quaternizing pyridyl ammonium salt with vinyl pyridine via 5-chloromethyl salicylaldehyde.

[0007] As an optimization, the mass ratio of the sodium carboxymethyl starch, acrylamide and modified vinyl pyridine is 3:12~15:6~8.

[0008] As an optimization, the modified denitrification resin includes the following preparation steps: S1. Weigh sodium carboxymethyl starch, acrylamide, and modified vinyl pyridine in a mass ratio of 3:12-15:6-8; add sodium carboxymethyl starch to deionized water 40-45 times the mass of sodium carboxymethyl starch, stir to dissolve, add acrylamide and grafted vinyl pyridine, then add potassium persulfate 0.08-0.1 times the mass of sodium carboxymethyl starch and N, N-methylenebisacrylamide 0.004-0.006 times the mass of sodium carboxymethyl starch, stir evenly, and prepare a polymerization solution; then add the polymerization solution dropwise to the polymerization solution. The method comprises the following steps: adding epichlorohydrin in an amount of 0.2 to 0.3 times the mass of sodium carboxymethyl starch to a cyclohexane solution with a volume of 0.5 to 0.7 times the mass of the solution, stirring at a temperature of 30 to 40°C for 30 to 40 minutes, raising the temperature to 60 to 70°C, stirring and reacting for 2 to 2.5 hours to obtain a mixed mother liquor, and then adding the mixed mother liquor to a coagulation solution with a volume of 10 to 15 times the volume of the mixed mother liquor to solidify into balls, standing for 30 to 40 minutes, filtering and washing with deionized water for 3 to 5 times to obtain preliminary cross-linked microspheres, and then performing secondary cross-linking to obtain cross-linked microspheres; S2. Add thiosemicarbazide to anhydrous ethanol in an amount of 12 to 15 times the mass of thiosemicarbazide, stir evenly, then add cross-linked microspheres in an amount of 2 to 5 times the mass of thiosemicarbazide, then add acetic acid in an amount of 0.2 to 0.3 times the mass of thiosemicarbazide, then stir and reflux for 6 to 7 hours, filter, extract with ethanol through a Soxhlet extractor for 24 to 26 hours, and then vacuum dry to obtain a modified denitrification resin.

[0009] As an optimization, the coagulation solution is prepared by mixing anhydrous sodium sulfate, sodium hydroxide, deionized water and anhydrous ethanol in a mass ratio of 1:1.2~1.4:22~25:0.15~0.2 and stirring evenly.

[0010] As an optimization, the cyclohexane solution is prepared by mixing cyclohexane and polycurate in a mass ratio of 75-80:1 and stirring them evenly.

[0011] As an optimization, the secondary cross-linking includes the following preparation steps: the preliminary cross-linked microspheres are extracted with ethanol using a Soxhlet extractor for 3 to 4 hours, then washed with ethanol and deionized water 3 to 5 times respectively, dehydrated and placed in a sodium hydroxide aqueous solution with a pH of 13 that is 10 to 12 times the mass of the preliminary cross-linked microspheres, then added with epichlorohydrin at a mass of 0.1 to 0.2 times the mass of the preliminary cross-linked microspheres, stirred and reacted at a temperature of 60 to 70°C for 2 to 2.5 hours, taken out, washed with deionized water until neutral, and then dehydrated to obtain cross-linked microspheres.

[0012] As an optimization, the modified vinyl pyridine includes the following preparation steps: adding vinyl pyridine to an acetonitrile solution with a mass of 10 to 12 times that of the vinyl pyridine, stirring evenly, dropwise adding 5-chloromethyl salicylaldehyde with a mass of 1.3 to 1.5 times that of the vinyl pyridine, stirring evenly, reacting at a temperature of 65 to 75° C. for 24 to 26 hours, and after the reaction is completed, rotary evaporation and then recrystallization through acetonitrile to obtain grafted vinyl pyridine.

[0013] As an optimization, the acetonitrile solution is prepared by mixing acetonitrile and ethyl acetate in a volume ratio of 1:3 to 3.5 and stirring evenly.

[0014] Compared with the prior art, the present invention has the following beneficial effects: The technical solution of the present application uses sodium carboxymethyl starch, acrylamide and modified vinyl pyridine quaternized with 5-chloromethyl salicylaldehyde as raw materials, and is grafted by reverse suspension polymerization and subjected to secondary cross-linking and thiosemicarbazide modification to obtain a modified denitrification resin. Due to the synergistic effect of the polysaccharide skeleton and the cross-linked network, the modified denitrification resin can still maintain structural stability in a high-salt environment. Its salt resistance can adapt to the high salt content in landfill leachate, avoiding the problem of unstable operation caused by high-salt inhibition in traditional biochemical treatment, and providing a reliable material basis for the full-scale treatment of leachate.

[0015] The pyridyl functional groups in the modified denitrification resin and the thiourea groups introduced by aminothiourea grafting form multiple chelating sites, which show strong adsorption capacity for heavy metal ions in landfill leachate. Through coordination, it efficiently captures heavy metals and reduces their toxic effects on microorganisms. At the same time, the secondary cross-linking structure of the resin enhances the mechanical strength, ensuring that it is not easy to break during the heavy metal adsorption process, thereby achieving long-term and stable operation.

[0016] What is particularly important is that after the resin chelates and adsorbs heavy metal ions, the synergistic effect of the pyridyl functional groups and thiourea groups on its surface can further promote the removal of nitrates. The enrichment of nitrate ions by the pyridyl group and the changes in the microenvironment formed after heavy metal adsorption improve the contact efficiency between nitrates and the active sites of the resin. Combined with the nitrification inhibition function of aminothiourea, the conversion path of ammonia nitrogen to nitrate is blocked, forming a synergistic denitrification mechanism of "heavy metal adsorption-nitrate removal", which significantly enhances the denitrification treatment capacity of landfill leachate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The following is a flow chart of the fully quantitative treatment process of landfill leachate in this application. DETAILED DESCRIPTION

[0018] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] Example 1: S1. Add vinyl pyridine to an acetonitrile solution with a mass of 10 times that of vinyl pyridine, stir evenly, then dropwise add 5-chloromethyl salicylaldehyde with a mass of 1.3 times that of vinyl pyridine, stir evenly, and react at a temperature of 65°C for 24 hours. After the reaction is completed, rotary evaporation and then recrystallization through acetonitrile to obtain grafted vinyl pyridine; the acetonitrile solution is prepared by mixing acetonitrile and ethyl acetate in a volume ratio of 1:3 and stirring evenly.

[0020] S2, weighing sodium carboxymethyl starch, acrylamide and modified vinyl pyridine in a mass ratio of 3:12:6; adding sodium carboxymethyl starch to deionized water 40 times the mass of sodium carboxymethyl starch, stirring to dissolve, adding acrylamide and grafted vinyl pyridine, and then adding potassium persulfate 0.08 times the mass of sodium carboxymethyl starch and N, N-methylenebisacrylamide 0.004 times the mass of sodium carboxymethyl starch, stirring evenly to prepare a polymerization solution; then adding the polymerization solution dropwise to a cyclohexane solution 0.5 times the volume of the polymerization solution, and adding epichlorohydrin 0.2 times the mass of sodium carboxymethyl starch, The temperature was 30° C. and stirred for 30 minutes, then the temperature was raised to 60° C. and the mixture was stirred for 2 hours to obtain a mixed mother liquor. The mixed mother liquor was then added to a coagulation solution with a volume 10 times that of the mixed mother liquor to solidify into balls. The mixture was allowed to stand for 30 minutes, filtered, and washed three times with deionized water to obtain preliminary cross-linked microspheres. The coagulation solution was prepared by mixing and stirring anhydrous sodium sulfate, sodium hydroxide, deionized water, and anhydrous ethanol in a mass ratio of 1:1.2:22:0.15. The cyclohexane solution was prepared by mixing and stirring cyclohexane and polycus acid ester in a mass ratio of 75:1.

[0021] S3. The preliminary cross-linked microspheres were extracted with ethanol using a Soxhlet extractor for 3 hours, and then washed with ethanol and deionized water three times each. After dehydration, they were placed in a sodium hydroxide aqueous solution with a pH of 13 that was 10 times the mass of the preliminary cross-linked microspheres. Then, epichlorohydrin was added at a mass of 0.1 times the mass of the preliminary cross-linked microspheres. The mixture was stirred and reacted at a temperature of 60°C for 2 hours. The mixture was taken out, washed with deionized water until neutral, and then dehydrated to obtain cross-linked microspheres.

[0022] S4. Add thiosemicarbazide to anhydrous ethanol with a mass of 12 times that of thiosemicarbazide, stir evenly, then add cross-linked microspheres with a mass of 2 times that of thiosemicarbazide, and then add acetic acid with a mass of 0.2 times that of thiosemicarbazide. After stirring and refluxing for 6 hours, filter and extract with ethanol through a Soxhlet extractor for 24 hours, and then vacuum dry to obtain a modified denitrification resin.

[0023] Example 2: S1. Add vinyl pyridine to an acetonitrile solution with a mass of 11 times that of vinyl pyridine, stir evenly, then dropwise add 5-chloromethyl salicylaldehyde with a mass of 1.4 times that of vinyl pyridine, stir evenly, and react at 70°C for 25 hours. After the reaction is completed, rotary evaporation and then recrystallization through acetonitrile to obtain grafted vinyl pyridine; the acetonitrile solution is prepared by mixing acetonitrile and ethyl acetate in a volume ratio of 1:3.25 and stirring evenly.

[0024] S2, weighing sodium carboxymethyl starch, acrylamide and modified vinyl pyridine in a mass ratio of 3:13.5:7; adding sodium carboxymethyl starch to deionized water 42.5 times the mass of sodium carboxymethyl starch, stirring to dissolve, adding acrylamide and grafted vinyl pyridine, and then adding potassium persulfate 0.09 times the mass of sodium carboxymethyl starch and N, N-methylenebisacrylamide 0.005 times the mass of sodium carboxymethyl starch, stirring evenly to prepare a polymerization solution; then adding the polymerization solution dropwise to a cyclohexane solution 0.6 times the volume of the polymerization solution, and adding epichlorohydrin 0.25 times the mass of sodium carboxymethyl starch, at a temperature of 100 ° C. The method comprises the following steps: stirring at 35° C. for 35 minutes, heating to 65° C., stirring for 2.25 hours to obtain a mixed mother liquor, and then adding the mixed mother liquor to a coagulation solution with a volume 12.5 times that of the mixed mother liquor to solidify into balls. The mixed mother liquor is allowed to stand for 35 minutes, filtered, and washed four times with deionized water to obtain preliminary cross-linked microspheres; the coagulation solution is prepared by mixing and stirring anhydrous sodium sulfate, sodium hydroxide, deionized water, and anhydrous ethanol in a mass ratio of 1:1.3:23.5:0.175; and the cyclohexane solution is prepared by mixing and stirring cyclohexane and polycus acid ester in a mass ratio of 77.5:1.

[0025] S3. The preliminary cross-linked microspheres were extracted with ethanol using a Soxhlet extractor for 3.5 hours, and then washed with ethanol and deionized water four times respectively. After dehydration, they were placed in a sodium hydroxide aqueous solution with a pH of 13 that was 11 times the mass of the preliminary cross-linked microspheres. Then, epichlorohydrin was added in an amount of 0.15 times the mass of the preliminary cross-linked microspheres. The mixture was stirred and reacted at a temperature of 65°C for 2.25 hours. The mixture was taken out, washed with deionized water until neutral, and then dehydrated to obtain cross-linked microspheres.

[0026] S4. Add thiosemicarbazide to anhydrous ethanol with a mass of 13.5 times that of thiosemicarbazide, stir evenly, then add cross-linked microspheres with a mass of 3.5 times that of thiosemicarbazide, and then add acetic acid with a mass of 0.25 times that of thiosemicarbazide. After stirring and reflux for 6.5 hours, filter and extract with ethanol through a Soxhlet extractor for 25 hours, and then vacuum dry to obtain a modified denitrification resin.

[0027] Example 3: S1. Add vinyl pyridine to an acetonitrile solution with a mass of 12 times that of vinyl pyridine, stir evenly, then dropwise add 5-chloromethyl salicylaldehyde with a mass of 1.5 times that of vinyl pyridine, stir evenly, and react at a temperature of 75°C for 26 hours. After the reaction is completed, rotary evaporation and then recrystallization through acetonitrile to obtain grafted vinyl pyridine; the acetonitrile solution is prepared by mixing acetonitrile and ethyl acetate in a volume ratio of 1:3.5 and stirring evenly.

[0028] S2, weighed sodium carboxymethyl starch, acrylamide and modified vinyl pyridine in a mass ratio of 3:15:8; added sodium carboxymethyl starch to 45 times the mass of sodium carboxymethyl starch in deionized water, stirred and dissolved, added acrylamide and grafted vinyl pyridine, then added potassium persulfate 0.1 times the mass of sodium carboxymethyl starch and N, N-methylenebisacrylamide 0.006 times the mass of sodium carboxymethyl starch, stirred evenly, and prepared into a polymerization solution; then the polymerization solution was added dropwise to a cyclohexane solution 0.7 times the volume of the polymerization solution, and 0.3 times the mass of sodium carboxymethyl starch was added epichlorohydrin, and heated at room temperature. The reaction mixture was stirred at a temperature of 40°C for 40 minutes, then heated to 70°C and stirred for 2.5 hours to obtain a mixed mother liquor, which was then added to a coagulation solution 15 times the volume of the mixed mother liquor to solidify into balls. The mixture was allowed to stand for 40 minutes, filtered, and washed 5 times with deionized water to obtain preliminary cross-linked microspheres. The coagulation solution was prepared by mixing and stirring anhydrous sodium sulfate, sodium hydroxide, deionized water, and anhydrous ethanol in a mass ratio of 1:1.4:25:0.2. The cyclohexane solution was prepared by mixing and stirring cyclohexane and polycus acid ester in a mass ratio of 80:1.

[0029] S3. The preliminary cross-linked microspheres were extracted with ethanol using a Soxhlet extractor for 4 hours, and then washed with ethanol and deionized water 5 times each. After dehydration, they were placed in a sodium hydroxide aqueous solution with a pH of 13 that was 12 times the mass of the preliminary cross-linked microspheres. Then, epichlorohydrin was added in an amount of 0.2 times the mass of the preliminary cross-linked microspheres. The mixture was stirred and reacted at a temperature of 70°C for 2.5 hours. The mixture was taken out, washed with deionized water until neutral, and then dehydrated to obtain cross-linked microspheres.

[0030] S4. Add thiosemicarbazide to anhydrous ethanol with a mass of 15 times that of thiosemicarbazide, stir evenly, then add cross-linked microspheres with a mass of 5 times that of thiosemicarbazide, and then add acetic acid with a mass of 0.3 times that of thiosemicarbazide. After stirring and refluxing for 7 hours, filter and extract with ethanol through a Soxhlet extractor for 26 hours, and then vacuum dry to obtain a modified denitrification resin.

[0031] Example 4: The only difference from Example 2 is that the "modified vinyl pyridine" in step S2 is changed to "vinyl pyridine", and step S4 is not performed; Example 5:

[0032] The only difference from Example 2 is that step S4 is not performed; The materials prepared in Examples 1 to 5 were subjected to the following performance tests. The test methods are as follows and the test results are shown in Table 1 below: Prepare multiple groups of 50 mg of the materials prepared in Examples 1 to 5 and add them to 50 mL of nitrate (56.4 mg / L) solution, 50 mL of mixed salt (nitrate (56.4 mg / L) + Cl-1 (250mg / L)) solution, 50mL of mixed salt (nitrate (56.4mg / L) + Cl -1 (250 mg / L)) + metal ion (50 mg / L) solution was added and continuously shaken. After 60 minutes, the supernatant was extracted and the nitrate adsorption amount was measured using an electrochemical workstation; Table 1 ; The data in Table 1 show that the denitrification resins prepared in Examples 1 to 3 of the present application have good salt tolerance and denitrification treatment capabilities.

[0033] Among them, the various indicators of Example 4 also performed well. The main reason for its performance degradation may be that it was not modified with 5-chloromethyl salicylaldehyde, resulting in poor hydrophilicity. In Example 5, since thiosemicarbazide modification was not used, the nitrification inhibition ability was lacking. Although the denitrification ability of each group of experiments was significantly improved after the addition of metal ions, the data improvement in Examples 4 and 5 was obviously lower than that of the denitrification resins in Examples 1 to 3. This is because the metal ions themselves have a certain degree of denitrification ability, but in Examples 4 and 5, since thiosemicarbazide was not grafted, although they have a certain degree of heavy metal adsorption ability, they lack synergistic effect and do not produce good nitrification inhibition.

[0034] Example 6: Currently, there are roughly three process routes for full-scale treatment: 1. Pretreatment + biochemical treatment + advanced oxidation (Fenton and other chemical oxidation) + biochemical treatment (safety section); 2. Pretreatment + membrane concentration + MVR evaporation + mother liquor solidification; 3. Pretreatment + biochemical treatment + SMT-DT high-efficiency catalytic oxidation + biochemical treatment (safety section). The advantages and disadvantages of these three treatment approaches are shown in Table 2 below: project Pretreatment + biochemical treatment + advanced oxidation Pretreatment + membrane concentration + MVR evaporation + mother liquor solidification Pretreatment + biochemical treatment + SMT-DT high-efficiency catalytic oxidation + biochemical treatment (safety section) Process Introduction First, a portion of COD, ammonia nitrogen, and total nitrogen are degraded through biochemical treatment. At the end of the treatment, catalytic oxidation and other processes are used to generate hydroxyl radicals to force the oxidation of organic matter and ammonia nitrogen in the leachate. The leachate is then treated in a biochemical system to achieve standard discharge. Through pretreatment to remove hardness, the suspended solids and hardness of the leachate meet the requirements of the membrane system, and then the concentration is reduced through the membrane system, and then the concentrated liquid is evaporated to achieve the discharge standard of the effluent. First, a portion of COD, ammonia nitrogen, total nitrogen, etc. are degraded through biochemical treatment. At the end of the treatment, electrocatalytic oxidation is used to utilize the catalytic activity of electrodes or catalytic materials to produce a large number of highly oxidizing free radicals to degrade organic pollutants. At the same time, ammonia nitrogen and total nitrogen can be removed. Then, the leachate is further treated through a biochemical system to achieve standard discharge. Investment costs Higher Higher Higher Running costs Higher Higher Higher Outlet water quality Generally, there is a risk of exceeding the total nitrogen standard Excellent Excellent System stability The entire process uses biological and chemical methods, which have extremely low tolerance to water quality fluctuations. Operating parameters such as dosage change dynamically, resulting in poor system stability and the risk of exceeding the total nitrogen standard. The whole process is a physical reaction, the system is extremely stable, and the salt in the leachate is removed at the same time. The entire process adopts biological and electrical methods, and does not require the addition of hazardous chemicals such as acids and oxidants. It can achieve full automatic control of the oxidation stage and has good system stability. Demand for hazardous chemicals sulfuric (hydrochloric) acid, hydrogen peroxide sulfuric acid (hydrochloric acid) none Hazardous waste generation Sludge containing a large amount of iron salts needs to be tested to see if it is a hazardous waste component. Whether the salt from evaporation and crystallization or the solid from solidified mother liquor is a hazardous waste component needs to be tested none This application combines the three aforementioned fully automated processes and optimizes their design. The optimized process flow is as follows: pretreatment + biochemical treatment + SMT-DT high-efficiency catalytic oxidation + integrated special-effect bacteria MBR system (safety section) + denitrification resin treatment (safety section). This design combines the advantages of the three aforementioned fully automated processes and introduces two safety sections as follow-up safeguards to improve system redundancy. Specific reference for the full quantitative treatment process of landfill leachate Figure 1 : Pretreatment in the regulating tank: leachate is introduced into the regulating tank, water quality and quantity are adjusted by the water inlet pump, and the water level is monitored in real time using a liquid level meter; Combined treatment in biochemical pool: After pre-treatment in the regulating pool, the water enters the biochemical pool, where it is treated and degraded by an aeration fan, and combined with a reflux system to achieve biological nitrogen and phosphorus removal; SMT-DT high-efficiency catalytic oxidation deep treatment: The effluent from the biochemical pool passes through the SMT-DT high-efficiency catalytic oxidation module, and uses an external electric field to generate a magnetic field for two-phase catalytic oxidation. The SMT-DT high-efficiency catalytic oxidation deep treatment adopts an SME-DT high-efficiency catalytic oxidation wastewater treatment device introduced in CN202510398742.2. When in use, the water flows through the gap between the axis of the first disc and the positive electrode cylinder, and the gap between the second disc and the negative electrode cylinder in turn. The water flow is in full contact with the surfaces of the first disc and the second disc. At the same time, when the electromagnet slides, it can change the position of the magnetic field so that the magnetic lines of force cut the water flow, which is beneficial to improving the efficiency of catalytic oxidation and optimizing the effluent water quality. In addition, the electromagnet can slide on the outer wall of the fixed tube, and a magnetic field can be generated by the electromagnet. Under the synergistic effect of the magnetic field and the electric field, the water flow is subjected to two-phase catalytic oxidation, thereby improving the treatment efficiency. Integrated special-effect bacteria MBR system: The effluent from SMT-DT catalytic oxidation treatment is separated by the MBR membrane system. The water production pump improves the water quality. The backwash pump regularly maintains the membrane components. An integrated high-efficiency bacteria biological denitrification module is connected and halophilic denitrifying bacteria are added to promote denitrification. After denitrification, the wastewater enters the secondary MBR membrane, where ammonia nitrogen and carbon sources are further removed by controlling the residence time. Denitrification resin treatment: The final effluent passes through the denitrification resin tank, filled with modified denitrification resin to adsorb residual nitrates and achieve standard discharge.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be encompassed therein. Any reference in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A fully quantitative treatment process for landfill leachate, characterized in that: The following steps are involved: Pretreatment in the regulating tank: leachate is introduced into the regulating tank, water quality and quantity are adjusted by the water inlet pump, and the water level is monitored in real time using a liquid level meter; Combined treatment in biochemical pool: After pre-treatment in the regulating pool, the water enters the biochemical pool, where it is treated and degraded by an aeration fan, and combined with a reflux system to achieve biological nitrogen and phosphorus removal; SMT-DT high-efficiency catalytic oxidation deep treatment: The effluent from the biochemical pool passes through the SMT-DT high-efficiency catalytic oxidation module, which uses an external electric field to generate a magnetic field for two-phase catalytic oxidation; Integrated special-effect bacteria MBR system: The effluent from SMT-DT catalytic oxidation treatment is separated by the MBR membrane system. The water production pump improves the water quality. The backwash pump regularly maintains the membrane components. An integrated high-efficiency bacteria biological denitrification module is connected and halophilic denitrifying bacteria are added to promote denitrification. After denitrification, the wastewater enters the secondary MBR membrane, where ammonia nitrogen and carbon sources are further removed by controlling the residence time. Denitrification resin treatment: The final effluent passes through the denitrification resin tank, filled with modified denitrification resin to adsorb residual nitrates to achieve standard discharge; The modified denitrification resin comprises: sodium carboxymethyl starch, acrylamide and modified vinyl pyridine; The modified denitrification resin is prepared by grafting acrylamide and modified vinyl pyridine onto sodium carboxymethyl starch using sodium carboxymethyl starch, acrylamide and modified vinyl pyridine through reverse suspension polymerization, and then grafting and modifying the resin using thiosemicarbazide after secondary cross-linking and curing.

2. The full-scale treatment process for landfill leachate according to claim 1, characterized in that: The modified vinyl pyridine is prepared by quaternizing pyridyl ammonium salt with vinyl pyridine through 5-chloromethyl salicylaldehyde.

3. The fully quantitative treatment process for landfill leachate according to claim 1, characterized in that: The mass ratio of the sodium carboxymethyl starch, acrylamide and modified vinyl pyridine is 3:12-15:6-8.

4. The full-scale treatment process for landfill leachate according to claim 1, characterized in that: The modified denitrification resin comprises the following preparation steps: S1. Weigh sodium carboxymethyl starch, acrylamide, and modified vinyl pyridine in a mass ratio of 3:12-15:6-8; add sodium carboxymethyl starch to deionized water 40-45 times the mass of sodium carboxymethyl starch, stir to dissolve, add acrylamide and grafted vinyl pyridine, then add potassium persulfate 0.08-0.1 times the mass of sodium carboxymethyl starch and N, N-methylenebisacrylamide 0.004-0.006 times the mass of sodium carboxymethyl starch, stir evenly, and prepare a polymerization solution; then add the polymerization solution dropwise to the polymerization solution. The method comprises the following steps: adding epichlorohydrin in an amount of 0.2 to 0.3 times the mass of sodium carboxymethyl starch to a cyclohexane solution with a volume of 0.5 to 0.7 times the mass of the solution, stirring at a temperature of 30 to 40°C for 30 to 40 minutes, raising the temperature to 60 to 70°C, stirring and reacting for 2 to 2.5 hours to obtain a mixed mother liquor, and then adding the mixed mother liquor to a coagulation solution with a volume of 10 to 15 times the volume of the mixed mother liquor to solidify into balls, standing for 30 to 40 minutes, filtering and washing with deionized water for 3 to 5 times to obtain preliminary cross-linked microspheres, and then performing secondary cross-linking to obtain cross-linked microspheres; S2. Add thiosemicarbazide to anhydrous ethanol in an amount of 12 to 15 times the mass of thiosemicarbazide, stir evenly, then add cross-linked microspheres in an amount of 2 to 5 times the mass of thiosemicarbazide, then add acetic acid in an amount of 0.2 to 0.3 times the mass of thiosemicarbazide, then stir and reflux for 6 to 7 hours, filter, extract with ethanol through a Soxhlet extractor for 24 to 26 hours, and then vacuum dry to obtain a modified denitrification resin.

5. The full-scale treatment process for landfill leachate according to claim 4, characterized in that: The coagulation solution is prepared by mixing anhydrous sodium sulfate, sodium hydroxide, deionized water and anhydrous ethanol in a mass ratio of 1:1.2-1.4:22-25:0.15-0.2 and stirring evenly.

6. The full-scale treatment process for landfill leachate according to claim 4, characterized in that: The cyclohexane solution is prepared by mixing cyclohexane and polycubic acid ester in a mass ratio of 75-80:1 and stirring them uniformly.

7. The full-scale treatment process for landfill leachate according to claim 4, characterized in that: The secondary crosslinking comprises the following preparation steps: extracting the preliminary crosslinked microspheres with ethanol using a Soxhlet extractor for 3 to 4 hours, then washing them with ethanol and deionized water for 3 to 5 times respectively, dehydrating them and then placing them in a sodium hydroxide aqueous solution with a pH of 13 that is 10 to 12 times the mass of the preliminary crosslinked microspheres, then adding epichlorohydrin that is 0.1 to 0.2 times the mass of the preliminary crosslinked microspheres, stirring and reacting at a temperature of 60 to 70° C. for 2 to 2.5 hours, taking them out, washing them with deionized water until neutral, and then dehydrating them to obtain crosslinked microspheres.

8. The fully quantitative treatment process for landfill leachate according to claim 4, characterized in that: The modified vinyl pyridine comprises the following preparation steps: adding vinyl pyridine to an acetonitrile solution with a mass of 10 to 12 times that of the vinyl pyridine, stirring evenly, dropwise adding 5-chloromethyl salicylaldehyde with a mass of 1.3 to 1.5 times that of the vinyl pyridine, stirring evenly, reacting at a temperature of 65 to 75° C. for 24 to 26 hours, and after the reaction is completed, rotary evaporation and then recrystallization through acetonitrile to obtain grafted vinyl pyridine.

9. The full-scale treatment process for landfill leachate according to claim 8, characterized in that: The acetonitrile solution is prepared by mixing acetonitrile and ethyl acetate in a volume ratio of 1:3-3.5 and stirring evenly.

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