A method for simultaneous denitrification and carbon removal of high-salt landfill leachate in industrial parks

Abstract

A simultaneous denitrification and carbon removal method for high-salt landfill leachate from industrial parks includes adding magnesium salt to the leachate to remove ammonia nitrogen and total phosphorus from the leachate; adding a coagulant to the leachate to agglomerate fine particles into larger ones; then using a flocculant to further enlarge and compact the particles, forming rapidly settling large flocs, thereby removing ammonia nitrogen from the leachate and adsorbing macromolecular organic matter in the leachate; and performing thiosulfate-enhanced persulfate advanced oxidation, which involves adding an oxidant to the leachate to generate sulfate radicals, destroying the structure of organic matter and effectively degrading refractory organic matter. Finally, adding sodium hypochlorite as an oxidant to the leachate to remove remaining ammonia nitrogen and organic matter, ensuring that pollutants in the leachate are substantially removed. The present invention can effectively remove ammonia nitrogen, organic matter, and heavy metals present in high-salt industrial landfill leachate, achieving harmless leachate treatment, improving treatment efficiency, and reducing treatment costs.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial waste treatment, and in particular to a method for simultaneous denitrification and decarbonization of high-salt landfill leachate in industrial parks. Background Art

[0002] With the rapid development of cities, the continuous increase in industrial production activities, and the continuous improvement of people's living standards, the output of waste and garbage in industrial parks has also increased dramatically. Currently, landfill disposal is still the main method for industrial waste treatment in my country. The leachate generated during landfilling has become a global problem that needs to be urgently treated. Because landfill materials are mainly construction waste or industrial waste, they have complex composition, high concentrations of pollutants such as organic matter and ammonia nitrogen, and contain high concentrations of heavy metals and toxic substances such as industrial production residues, making them difficult to treat.

[0003] Currently, the treatment of high-salinity industrial landfill leachate is primarily based on physicochemical and biological methods. Traditional biological methods, such as the activated sludge process, have poor resistance to environmental stresses associated with high-salinity wastewater, and microorganisms are unable to adapt to the environmental conditions of high-salinity wastewater. Pretreatment processes such as coagulation, evaporation, desalination, and even dilution are required, which undoubtedly increases the cost and procedures for treating high-salinity wastewater. Physicochemical methods such as coagulation, sedimentation, and filtration have limited effectiveness against organic matter and are typically used only as pre- or post-treatment processes. The treatment of high-salinity industrial landfill leachate has become an industry-wide and global challenge, jeopardizing both landfill safety and the stability of leachate treatment systems. Summary of the Invention

[0004] Based on the above problems, the present invention provides a method for simultaneous denitrification and decarbonization of high-salt industrial landfill leachate in industrial parks, which can effectively remove ammonia nitrogen, organic matter and heavy metals with high content in high-salt industrial landfill leachate, realize the harmless treatment of leachate, improve the treatment efficiency of high-salt industrial landfill leachate in industrial parks, and reduce the treatment cost.

[0005] A method for simultaneous denitrification and carbon removal of high-salt landfill leachate in an industrial park, comprising the following steps:

[0006] Step S1: struvite precipitation: adding magnesium salt to the leachate to remove ammonia nitrogen and total phosphorus in the leachate;

[0007] Step S2: Iron-based coagulation: A coagulant is added to the leachate to aggregate fine particles into larger particles. A flocculant is then used to further enlarge and compact the particles, forming large flocs that settle rapidly. This further removes ammonia nitrogen from the leachate and adsorbs macromolecular organic matter in the leachate, reducing the load on subsequent treatment procedures.

[0008] Step S3: Thiosulfate-enhanced persulfate advanced oxidation: adding an oxidant to the leachate to generate sulfate free radicals, which destroy the structure of organic matter and effectively degrade refractory organic matter;

[0009] Step S4: Advanced treatment: Sodium hypochlorite oxidant is added to the leachate to further remove the remaining ammonia nitrogen and organic matter, ensuring that the pollutants in the leachate are basically removed.

[0010] Preferably, in the struvite precipitation in step S1 of the present invention, the pH is adjusted to a weak alkaline state before adding the magnesium salt, and the magnesium ammonium phosphate crystals in the precipitate are recovered, thereby realizing the resource utilization of ammonia nitrogen and total phosphorus.

[0011] Preferably, the magnesium salt of the present invention is magnesium chloride.

[0012] Preferably, in the iron-based coagulation of step S2 of the present invention, the coagulant, flocculant, and leachate are thoroughly mixed by stirring under acidic conditions, and the flocculent leachate after coagulation is allowed to settle by gravity, achieving solid-liquid separation. The resulting sludge is then dehydrated and dried, and the dried sludge is incinerated.

[0013] Preferably, the coagulant of the present invention is ferric chloride; and the flocculant is anionic polyacrylamide.

[0014] Preferably, in the thiosulfate-enhanced persulfate advanced oxidation of step S3 of the present invention, a sodium persulfate oxidation method is used, the pH is adjusted to neutral, and the organic matter: sodium persulfate: thiosulfate mass ratio is 1:18:0.18. The iron ions introduced in step S2 are converted into ferrous ions by sodium thiosulfate, which activates the sodium persulfate oxidation, and the oxidant and the leachate are fully mixed by heating and stirring in the reactor. The reaction time is generally 2h.

[0015] Preferably, in the deep treatment of step S4 of the present invention, sodium hypochlorite is used to treat the remaining organic matter and ammonia nitrogen, and sodium ions and chloride ions are introduced to be recycled in the subsequent evaporation and crystallization process. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution (such as sodium hydroxide) to facilitate subsequent treatment.

[0016] Preferably, the alkaline solution of the present invention is sodium hydroxide.

[0017] The synchronous denitrification and decarbonization process for high-salt landfill leachate in industrial parks of the present invention utilizes the coupling of struvite precipitation-iron-based coagulation-thiosulfate-enhanced persulfate advanced oxidation-deep treatment and other technologies. Most of the ammonia nitrogen and total phosphorus in the leachate are recovered through struvite precipitation. Then, flocs formed in the iron-based coagulation process adsorb macromolecular organic matter and ammonia nitrogen in the leachate, thereby reducing the load of subsequent advanced oxidation and making it easier for sodium persulfate to oxidize organic matter in the leachate. Finally, deep treatment is performed using sodium hypochlorite, thereby achieving maximum denitrification and decarbonization of the high-salt landfill leachate in industrial parks, thereby achieving the technical effects of improving treatment efficiency and reducing operating costs, and solving the technical problem that high-salt landfill leachate in industrial parks is difficult to treat. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic flow chart of the simultaneous denitrification and decarbonization method of the present invention.

[0019] Figure 2 This is a three-dimensional fluorescence spectrum diagram of the removal effect of refractory organic matter in leachate using the simultaneous denitrification and carbon removal method of the present invention, wherein a is high-salt leachate, b is struvite precipitation, c is iron-based coagulation, d is thiosulfate-enhanced persulfate advanced oxidation, and e is deep treatment.

[0020] Figure 3 The figure is an ultraviolet-visible spectrum diagram of the removal effect of refractory organic matter in leachate using the simultaneous denitrification and carbon removal method of the present invention. DETAILED DESCRIPTION

[0021] The technical solution of the present invention is described in detail below with reference to the accompanying drawings:

[0022] like Figure 1 As shown, a method for simultaneous denitrification and carbon removal of high-salt landfill leachate in an industrial park comprises the following steps:

[0023] Step S1: struvite precipitation: adding magnesium salt to the leachate to remove ammonia nitrogen and total phosphorus in the leachate.

[0024] The pH is adjusted to a weak alkaline state before adding the magnesium salt, and the magnesium ammonium phosphate crystals in the precipitation are recovered, thereby realizing the resource utilization of ammonia nitrogen and total phosphorus. The magnesium salt is magnesium chloride.

[0025] Step S2: Iron-based coagulation: A coagulant is added to the leachate to agglomerate fine particles into larger particles. A flocculant is then used to further enlarge and compact the particles, forming large flocs that settle rapidly. This further removes ammonia nitrogen from the leachate and adsorbs large organic molecules in the leachate, reducing the load on subsequent treatment procedures.

[0026] Under acidic conditions, the coagulant, flocculant, and leachate are thoroughly mixed through stirring. The coagulated leachate then settles floccules by gravity, achieving solid-liquid separation. The resulting sludge is then dehydrated and dried, and the dried sludge is incinerated. The coagulant is ferric chloride, and the flocculant is anionic polyacrylamide.

[0027] Step S3: Thiosulfate-enhanced persulfate advanced oxidation: adding an oxidant to the leachate to generate sulfate free radicals, destroying the structure of organic matter and effectively degrading refractory organic matter.

[0028] Using the sodium persulfate oxidation method, the pH is adjusted to neutral, and the organic matter: sodium persulfate: thiosulfate ion is added in a mass ratio of 1:18:0.18. The iron ions introduced in step S2 are converted into ferrous ions by sodium thiosulfate, which activates the sodium persulfate oxidation. The oxidant and leachate are fully mixed by heating and stirring in the reactor. The reaction time is generally 2 hours.

[0029] Step S4: Advanced treatment: Sodium hypochlorite oxidant is added to the leachate to further remove the remaining ammonia nitrogen and organic matter, ensuring that the pollutants in the leachate are basically removed.

[0030] Sodium hypochlorite is used to treat the remaining organic matter and ammonia nitrogen, while introducing sodium ions and chloride ions for recycling in the subsequent evaporation and crystallization process. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution (such as sodium hydroxide) to facilitate subsequent processing. The alkaline solution is sodium hydroxide.

[0031] Example 1

[0032] The process experiment verification was carried out using actual leachate collected in October 2024. The leachate used in this experiment was high-salt industrial waste leachate with a pH value of 8.42, an organic matter concentration of 3314.12 mg / L, an ammonia nitrogen concentration of 1724.25 mg / L, and a conductivity of 182 mS / cm.

[0033] Step S1: Struvite precipitation: Remove ammonia nitrogen and total phosphorus from the leachate. Adjust the leachate pH to a weakly alkaline pH (approximately 7-8), add an appropriate amount of magnesium chloride and struvite crystals treated at 200°C as a magnesium source and seed crystals, respectively. Stir and react for approximately 30 minutes, then allow to settle. Recover the struvite crystals from the precipitate.

[0034] Step S2: Iron-based coagulation: Adjust the pH of the leachate to a weak acidity (about 5), add an appropriate amount of coagulant ferric chloride, and coagulate at high speed for 5 minutes. Then, add an appropriate amount of flocculant polyacrylamide, coagulate at medium speed for 5 minutes, and coagulate at low speed for 10 minutes to condense the fine suspended matter into larger flocs, further remove ammonia nitrogen from the leachate, and adsorb the macromolecular organic matter in the leachate. Let it settle and achieve solid-liquid separation. The generated sludge is dehydrated and dried, and the dried sludge is incinerated to reduce the volume.

[0035] Step S3: Thiosulfate-enhanced persulfate advanced oxidation: The pH of the coagulation supernatant was adjusted to neutral (approximately 7), and sodium persulfate was added in a mass ratio of organic matter: sodium persulfate: thiosulfate of 1:18:0.18. The mixture was heated and stirred at 70°C to destroy the structure of the organic matter, improve its biodegradability, and effectively degrade the refractory organic matter. The reaction time was 2 hours.

[0036] Step S4: Advanced treatment: The pH of the advanced oxidation effluent is adjusted to acidic (about 4), and an appropriate amount of sodium hypochlorite is added for treatment. The reaction time is 60 minutes to further remove the remaining ammonia nitrogen and organic matter to ensure that the pollutants in the leachate are basically removed. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution (such as sodium hydroxide) to facilitate subsequent treatment.

[0037] After treatment with this process, the leachate had a pH of 8.5, an organic matter concentration of 120.97 mg / L, an ammonia nitrogen concentration of 11.75 mg / L, and a conductivity of 155 mS / cm. The leachate's various indicators before and after the treatment were also statistically analyzed, as shown in the table below.

[0038] index Ammonia nitrogen (mg / L) COD (mg / L) Cu (mg / L) Fe (mg / L) Ni (mg / L) As (mg / L) Cost (yuan) Raw water quality 1724.25 3314.12 7.47 131.11 23.27 109.51 500-600 Water quality after process treatment 11.75 120.97 0.19 1.25 0.24 0.35 235.88

[0039] At the same time, the effect diagram of removing refractory organic matter in leachate by using the simultaneous denitrification and carbon removal method of the present invention is shown. Figure 2 A three-dimensional fluorescence spectrum showing the removal effect of difficult-to-degrade organic matter in leachate using the simultaneous denitrification and carbon removal method of the present invention, wherein a is high-salt leachate, b is struvite precipitation, c is iron-based coagulation, d is thiosulfate-enhanced persulfate advanced oxidation, and e is deep treatment. Figure 3 What is shown is the UV-visible spectrum of the removal effect of the simultaneous denitrification and carbon removal method of the present invention on the refractory organic matter in the leachate.

[0040] From the three-dimensional fluorescence spectrum, it can be seen that the main components of the high-salt leachate are fulvic acid-like and humic acid-like substances. After treatment with the process of the present invention, the fulvic acid-like and humic acid-like substances are completely removed, leaving only some biosoluble byproducts. From the ultraviolet-visible spectrum, it can be seen that the organic matter content in the treated high-salt leachate is greatly reduced, and the ultraviolet absorption peak before and after treatment has undergone a blue shift, indicating that the molecular conjugation effect in the treated water sample is reduced, indicating that the process of the present invention has a high removal efficiency for organic matter with a conjugated benzene ring structure, and the molecular weight and degree of polymerization of the organic matter are reduced after treatment. It shows that the process system of the present invention can effectively degrade difficult-to-degrade organic matter in industrial waste leachate.

[0041] Example 2

[0042] The process experiment verification was carried out using actual leachate collected in April 2024. The leachate used in this experiment was high-salt industrial waste leachate with a pH value of 8.83, an organic matter concentration of 2760.12 mg / L, an ammonia nitrogen concentration of 1754.25 mg / L, and a conductivity of 181.1 mS / cm.

[0043] Step S1: Struvite precipitation: Remove ammonia nitrogen and total phosphorus from the leachate. Adjust the leachate pH to a weakly alkaline pH (approximately 7-8), add an appropriate amount of magnesium chloride and struvite crystals treated at 200°C as a magnesium source and seed crystals, respectively. Stir and react for approximately 30 minutes, then allow to settle. Recover the struvite crystals from the precipitate.

[0044] Step S2: Iron-based coagulation: Adjust the pH of the leachate to a weak acidity (about 5), add an appropriate amount of coagulant ferric chloride, and coagulate at high speed for 5 minutes. Then, add an appropriate amount of flocculant polyacrylamide, coagulate at medium speed for 5 minutes, and coagulate at low speed for 10 minutes to condense the fine suspended matter into larger flocs, further remove ammonia nitrogen from the leachate, and adsorb the macromolecular organic matter in the leachate. Let it settle and achieve solid-liquid separation. The generated sludge is dehydrated and dried, and the dried sludge is incinerated to reduce the volume.

[0045] Step S3: Thiosulfate-enhanced persulfate advanced oxidation: The pH of the coagulation supernatant was adjusted to neutral (approximately 7), and sodium persulfate was added in a mass ratio of organic matter: sodium persulfate: thiosulfate of 1:18:0.18. The mixture was heated and stirred at 70°C to destroy the structure of the organic matter, improve its biodegradability, and effectively degrade the refractory organic matter. The reaction time was 2 hours.

[0046] Step S4: Advanced treatment: The pH of the advanced oxidation effluent is adjusted to acidic (about 4), and an appropriate amount of sodium hypochlorite is added for treatment. The reaction time is 60 minutes to further remove the remaining ammonia nitrogen and organic matter to ensure that the pollutants in the leachate are basically removed. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution (such as sodium hydroxide) to facilitate subsequent treatment.

[0047] After treatment with this process, the leachate had a pH of 8.5, an organic matter concentration of 98.68 mg / L, an ammonia nitrogen concentration of 8.17 mg / L, and a conductivity of 143.2 mS / cm. The leachate's various indicators before and after the process were also statistically analyzed, as shown in the table below.

[0048] index Ammonia nitrogen (mg / L) COD (mg / L) Cu (mg / L) Fe (mg / L) Ni (mg / L) As (mg / L) Raw water quality 1754.25 2760.12 17.47 51.11 42.27 89.51 Water quality after process treatment 8.17 98.68 1.21 0.74 0.59 0.11

[0049] Example 3

[0050] The process experiment verification was carried out using actual leachate collected in December 2024. The leachate used in this experiment was high-salt industrial waste leachate with a pH value of 5.23, an organic matter concentration of 2445.37 mg / L, an ammonia nitrogen concentration of 1527.25 mg / L, and a conductivity of 172.8 mS / cm.

[0051] Step S1: Struvite precipitation: Remove ammonia nitrogen and total phosphorus from the leachate. Adjust the leachate pH to a weakly alkaline pH (approximately 7-8), add an appropriate amount of magnesium chloride and struvite crystals treated at 200°C as a magnesium source and seed crystals, respectively. Stir and react for approximately 30 minutes, then allow to settle. Recover the struvite crystals from the precipitate.

[0052] Step S2: Iron-based coagulation: Adjust the pH of the leachate to a weak acidity (about 5), add an appropriate amount of coagulant ferric chloride, and coagulate at high speed for 5 minutes. Then, add an appropriate amount of flocculant polyacrylamide, coagulate at medium speed for 5 minutes, and coagulate at low speed for 10 minutes to make the fine suspended matter condense into larger flocs, further remove ammonia nitrogen from the leachate, and remove the macromolecular organic matter in the leachate. Let it settle and achieve solid-liquid separation. The generated sludge is dehydrated and dried, and the dried sludge is incinerated to reduce the volume.

[0053] Step S3: Thiosulfate-enhanced persulfate advanced oxidation: The pH of the coagulation supernatant was adjusted to neutral (approximately 7), and sodium persulfate was added in a mass ratio of organic matter: sodium persulfate: thiosulfate of 1:18:0.18. The mixture was heated and stirred at 70°C to destroy the structure of the organic matter, improve its biodegradability, and effectively degrade the refractory organic matter. The reaction time was 2 hours.

[0054] Step S4: Advanced treatment: The pH of the advanced oxidation effluent is adjusted to acidic (about 4), and an appropriate amount of sodium hypochlorite is added for treatment. The reaction time is 60 minutes to further remove the remaining ammonia nitrogen and organic matter to ensure that the pollutants in the leachate are basically removed. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution (such as sodium hydroxide) to facilitate subsequent treatment.

[0055] After treatment with this process, the leachate had a pH of 8.43, an organic matter concentration of 132.11 mg / L, an ammonia nitrogen concentration of 5.26 mg / L, and a conductivity of 129.2 mS / cm. The leachate's various indicators before and after the treatment were also statistically analyzed, as shown in the table below.

[0056] index Ammonia nitrogen (mg / L) COD (mg / L) Cu (mg / L) Fe (mg / L) Ni (mg / L) As (mg / L) Raw water quality 1527.25 2445.37 11.37 84.17 29.55 64.89 Water quality after process treatment 5.26 132.11 0.81 1.34 0.67 0.29

[0057] Comparative example (compared with other processes)

[0058] The existing processes were compared using actual leachate collected in December 2024. The leachate used in this comparative experiment was high-salt industrial waste leachate with a pH of 5.23, an organic matter concentration of 2445.37 mg / L, an ammonia nitrogen concentration of 1527.25 mg / L, and a conductivity of 172.8 mS / cm. The processes compared were the Fenton advanced oxidation process and the activated carbon adsorption-sodium hypochlorite oxidation process.

[0059] Fenton advanced oxidation process: adjust the leachate to 2-3, add ferrous salt and hydrogen peroxide in a certain proportion, stir in the reactor to fully mix the ferrous salt and hydrogen peroxide, the reaction time is 60 minutes, and after the reaction is completed, adjust the pH to neutral or alkaline.

[0060] After treatment with the Fenton advanced oxidation process, the leachate pH was 7.5, the organic matter concentration was 189.14 mg / L, the ammonia nitrogen was 281.75 mg / L, and the conductivity was 161.4 mS / cm.

[0061] Activated carbon adsorption-sodium hypochlorite oxidation process: adjust the pH of the leachate to about 4, add powdered activated carbon in a certain proportion, aerate and stir in the reactor to allow the activated carbon to fully contact with the leachate, and the adsorption time is 120 minutes. After the adsorption is completed, stand and filter, add sodium hypochlorite in a certain proportion to the filtrate, and stir in the reactor to allow the sodium hypochlorite and the filtrate to fully react. The reaction time is 60 minutes.

[0062] After treatment with activated carbon adsorption-sodium hypochlorite oxidation process, the leachate pH was 3.24, the organic matter concentration was 414.34 mg / L, the ammonia nitrogen was 28.44 mg / L, and the conductivity was 157.9 mS / cm.

[0063] The final results of the three processes are compared in the table below.

[0064]

[0065] The advanced oxidation method used in the simultaneous denitrification and carbon removal method of the present invention is a sodium persulfate oxidation technology, in which ferrous ions are introduced for co-activation at the same time as traditional thermal activation.

[0066] The simultaneous denitrification and carbon removal method of the present invention, in step S2, by adding an iron salt coagulant, while removing ammonia nitrogen and macromolecular organic matter in the leachate by coagulation and precipitation, introduces trivalent iron ions, and then by adding a reducing agent sodium thiosulfate in step 3, the trivalent iron ions are reduced to divalent ferrous ions, which play an activating role in the sodium persulfate advanced oxidation process in step 3.

[0067] The simultaneous denitrification and carbon removal method of the present invention includes the recycling and utilization of resources such as ammonia nitrogen and total phosphorus in the leachate.

[0068] The simultaneous denitrification and carbon removal method of the present invention is applied in the field of high-salt landfill leachate treatment.

Claims

1. A method for simultaneous denitrification and carbon removal of high-salt landfill leachate in industrial parks, characterized in that: The steps include: Step S1: struvite precipitation: adding magnesium salt to the leachate to remove ammonia nitrogen and total phosphorus in the leachate; Step S2: Iron-based coagulation: A coagulant is added to the leachate to aggregate fine particles into larger particles. A flocculant is then used to further enlarge and compact the particles, forming large flocs that settle rapidly. This further removes ammonia nitrogen from the leachate and adsorbs macromolecular organic matter in the leachate, reducing the load on subsequent treatment procedures. Step S3: Thiosulfate-enhanced persulfate advanced oxidation: adding an oxidant to the leachate to generate sulfate radicals, which destroy the structure of organic matter and effectively degrade refractory organic matter; Step S4: Advanced treatment: Sodium hypochlorite oxidant is added to the leachate to further remove the remaining ammonia nitrogen and organic matter, ensuring that the pollutants in the leachate are basically removed.

2. The method for simultaneous denitrification and carbon removal of high-salt landfill leachate from an industrial park according to claim 1, characterized in that: In the struvite precipitation in step S1, the pH is adjusted to a weak alkaline state before adding the magnesium salt, and the magnesium ammonium phosphate crystals in the precipitate are recovered, thereby realizing the resource utilization of ammonia nitrogen and total phosphorus.

3. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 2, characterized in that: The above-mentioned magnesium salt is magnesium chloride.

4. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 1, characterized in that: In step S2, iron-based coagulation, the coagulant, flocculant, and leachate are thoroughly mixed by stirring under acidic conditions. Gravity settles the flocculent leachate after coagulation, achieving solid-liquid separation. The resulting sludge is then dehydrated and dried, and the dried sludge is incinerated.

5. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 4, characterized in that: The above-mentioned coagulant is ferric chloride; the flocculant is anionic polyacrylamide.

6. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 5, characterized in that: In the above-mentioned step S3 thiosulfate-enhanced persulfate advanced oxidation, a sodium persulfate oxidation method is used, the pH is adjusted to neutral, and the organic matter: sodium persulfate: thiosulfate ion is added in a mass ratio of 1:18:0.

18. The iron ions introduced in step S2 are converted into ferrous ions by sodium thiosulfate, which activates the sodium persulfate oxidation. The oxidant and the leachate are fully mixed by heating and stirring in the reactor. The reaction time is generally 2 hours.

7. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 1, characterized in that: In the above-mentioned step S4 deep treatment, sodium hypochlorite is used to treat the remaining organic matter and ammonia nitrogen, and sodium ions and chloride ions are introduced to be recycled in the subsequent evaporation and crystallization process. After the reaction is completed, the pH value is adjusted to neutral or weak alkaline with an alkaline solution to facilitate subsequent treatment.

8. The method for simultaneous denitrification and decarbonization of high-salt landfill leachate from an industrial park according to claim 7, characterized in that: The above alkaline solution is sodium hydroxide.

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