Landfill leachate extract as well as preparation method and application thereof in wastewater treatment

Abstract

The invention relates to a landfill leachate extract as well as a preparation method and application thereof in wastewater treatment. The landfill leachate extract is prepared by adding an extracting agent containing a mixture of sulfuric acid, tartaric acid, adipic acid and EDTA (Ethylene Diamine Tetraacetic Acid) and carrying out chemical reaction under the condition that the pH is not greater than 3.0, and further sequentially carrying out steps of high-speed stirring, low-speed stirring, aging crystallization and the like for sufficient reaction to form solid precipitate with the specific surface area of 250-350m < 2 > / g, and then carrying out leaching reaction with alkali liquor to obtain the landfill leachate extract with the average relative molecular weight of 500-20000. According to the landfill leachate extract disclosed by the invention, organic pollutants which are difficult to treat in industrial wastewater are reduced, and the treatment target can be quickly achieved; the method is used for industrial wastewater treatment, achieves an inter-process synergistic effect, improves the wastewater treatment efficiency by 20% or above, saves the treatment cost, and has good economic benefits and application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a garbage leachate extract and a preparation method thereof and application thereof in wastewater treatment. Background Art

[0002] Landfill leachate is a kind of sewage formed by the water content of the garbage itself, the water produced by the decomposition of organic matter, the surface precipitation and the water holding capacity in the overburden, and the groundwater pouring into the landfill during the collection, transportation, stacking and treatment of garbage. It is a kind of sewage formed by the water content of the garbage itself, the water produced by the decomposition of organic matter, the surface precipitation and the water holding capacity in the overburden, and the groundwater pouring into the landfill. It is recognized in the world as a high-concentration organic wastewater that is difficult to treat. It has complex components and contains non-chlorinated aromatic compounds such as humic acid, naphthalene, phenanthrene, etc. that are difficult to biodegrade, chlorinated aromatic compounds, phosphates, phthalates, phenolic compounds and aniline compounds and various metal ions, etc., especially the leachate of aging landfill garbage, which is more difficult to treat. In practice, there are still process problems for purifying humic acid and then comprehensively utilizing it. Patent applications CN100513335A Comprehensive treatment method for recycling humic acid in landfill leachate, CN101701025A A method for extracting humic acid from concentrated landfill leachate and treating wastewater, etc., are all about the way of extracting humic acid and treating it, but there is still a gap in its use for wastewater treatment.

[0003] Industrial wastewater comes from various industrial production activities, such as manufacturing, mining, chemical, pharmaceutical, textile, food processing, metallurgy, electricity, etc. Industrial wastewater may contain heavy metals, toxic compounds, suspended solids, grease, organic pollutants and other harmful substances. Among them, printing and dyeing wastewater is the wastewater discharged from printing and dyeing factories that mainly process cotton, linen, chemical fibers and their blended products. Printing and dyeing wastewater has the characteristics of large water volume, high content of organic pollutants, and large changes in water quality. It is one of the difficult industrial wastewaters to treat. The wastewater contains dyes, slurries, additives, oils, acids and alkalis, fiber impurities, sand substances, inorganic salts, etc. When treating printing and dyeing wastewater, when selecting a process method, the system operation should be simple, reliable, safe, and the operating cost should be minimized.

[0004] In view of the above, it is necessary to provide a solution that can achieve rapid, effective and economical wastewater treatment, reduce the difficult-to-biodegrade organic pollutants in industrial wastewater, achieve treatment goals in a shorter reaction time, save treatment costs, ensure the stable operation of subsequent treatment processes, and achieve wastewater and sewage discharge standards. Summary of the invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention aims to provide a landfill leachate extract and a preparation method thereof and application in wastewater treatment. The extract greatly reduces the difficult-to-biodegrade organic pollutants in the wastewater, can achieve the treatment target in a shorter reaction time, greatly saves the treatment cost, ensures the stable operation of the subsequent treatment process, and achieves the wastewater and sewage discharge meeting the standards.

[0006] In a first aspect, the present invention provides a method for preparing a landfill leachate extract, comprising the following steps:

[0007] S1, filtering the landfill leachate, adjusting the pH value of the filtrate to not more than 3.0 with an extractant, stirring, aging and crystallizing;

[0008] S2, filtering the solution after aging and crystallization in step S1 to obtain a filtrate and a filter residue;

[0009] S3, adding alkaline solution to the filter residue in step S2 for elution, and continuing to elute the filter residue with the solution generated by the elution for 3 to 5 times, and the eluent obtained after sufficient reaction is the landfill leachate extract.

[0010] Further, the extractant in step S1 is an aqueous solution including sulfuric acid, tartaric acid, adipic acid and EDTA, and the solute concentration in the aqueous solution is 50 to 300 g / L;

[0011] Furthermore, the mass ratio of the sulfuric acid, tartaric acid, adipic acid and EDTA is 92-96: 1-5: 1-3: 0.05-0.5.

[0012] Preferably, the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1.

[0013] Preferably, the pH in step S1 is 1.5-2.8.

[0014] Furthermore, the stirring and aging crystallization procedures of step S1 are: rapid stirring at 120-150 r / min for 30-60 min, then slow stirring at 40-60 r / min for 60-120 min, and further maintaining slow stirring at 10-20 r / min for aging crystallization for 2-12 h.

[0015] Furthermore, the specific surface area of ​​the filter residue in step S2 is 250 to 350 m 2 / g (dry basis).

[0016] Furthermore, the alkali solution in step S3 includes one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, and the mass concentration of the alkali solution is 5 to 50 g / L.

[0017] In a second aspect, the present invention provides a landfill leachate extract, which is prepared by the above-mentioned preparation method.

[0018] Furthermore, the landfill leachate extract is a dark brown liquid, which is a natural organic polymer mixture with an average relative molecular weight of 500 to 20,000.

[0019] In a third aspect, the present invention provides an application of the landfill leachate extract in wastewater treatment, wherein the wastewater includes chemical wastewater, metallurgical wastewater, pharmaceutical wastewater, printing and dyeing wastewater, electroplating wastewater, leather wastewater, etc., but is not limited to the above fields.

[0020] Furthermore, the present invention also provides a specific application method of the landfill leachate extract in wastewater treatment:

[0021] (1) adjusting the pH value of the landfill leachate to no more than 3.0 with a dilute sulfuric acid aqueous solution, then adding the landfill leachate extract of claim 5 to react, and filtering to obtain a filtrate and a filter residue;

[0022] (2) filtering the solution after the reaction in step (1) to obtain a filtrate and a filter residue;

[0023] (3) The filtrate obtained in step (2) is sent to a micro-electrolysis catalytic reactor, and the wastewater is further reacted in the micro-electrolysis catalytic reactor, and the reaction pH is 1.0 to 4.0 (the pH of the filtrate obtained in step (2) is completely matched with the micro-electrolysis catalytic reaction system, so there is no need to adjust the pH in this step, simplifying the treatment process). After the reaction is completed, the pH is adjusted to 8.0 to 8.5 for flocculation and precipitation treatment, and the treated liquid enters the next process to continue to complete the wastewater treatment normally;

[0024] (4) The filter residue obtained in step (2) is disposed of in a normal discharge yard.

[0025] (5) The treated liquid in step (2) is introduced into an ozone catalytic oxidation system for deep oxidation treatment for 40-60 minutes to achieve a COD emission standard of less than 100 mg / L.

[0026] Furthermore, in the step (1), the dosage of the landfill leachate extract is 0.5 to 10 mL per liter of wastewater.

[0027] Furthermore, in step (3), the micro-electrolysis catalytic reactor is selected from an iron-carbon micro-electrolysis catalytic reactor.

[0028] Furthermore, the filtrate in step (3) is sent to a micro-electrolysis catalytic reactor for reaction for 30 to 120 minutes, and then enters an air aeration tower for air aeration for 30 to 60 minutes.

[0029] Furthermore, the flocculation and precipitation steps in step (3) include adding 60-120 mg / L flocculant and / or 5-30 mg / L coagulant aid for treatment, the flocculant is PAC (polyaluminum chloride, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.), and the coagulant aid is PAM (polyacrylamide, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.).

[0030] The landfill leachate extract of the present invention is prepared by a method combining extraction with an extractant + flocculation + acid-base precipitation. Under acidic conditions (pH not greater than 3.0), on the one hand, the natural high-molecular organic mixture (mainly the beneficial components of humic acid, humic acid and fulvic acid) in the landfill leachate is precipitated and recycled. This type of humic acid has a high content in aged landfill leachate and can be degraded in nature for hundreds or even thousands of years. These substances are stable and difficult to biodegrade, but they are excellent natural materials. The present invention precipitates and recycles them; on the other hand, it can be coordinated with the iron-carbon micro-electrolysis reactor treatment in the wastewater treatment process, that is, the treatment The pH value of the treated filtrate is completely matched with the micro-electrolysis catalytic reaction system. No adjustment is required. It directly enters the micro-electrolysis catalytic reactor for reaction. It is first stirred quickly and then slowly. The main purpose is that the rapid stirring can make the added regulating acid and / or extract fully and evenly mixed with the treated landfill leachate to form small crystals with relatively uniform size and shape. Then slow stirring is conducive to the growth of crystals. It is further aged for a period of time. The purpose of aging is to make the chemical reaction sufficient and allow small crystals to form coarse crystals, so that the crystals containing natural high-molecular organic mixtures such as humic acid and fulvic acid have a larger specific surface area, which is convenient for filtration and washing, and economical to operate.

[0031] The invention obtains the landfill leachate extract by pre-treating the landfill leachate. The main component of the extract is humic acid, and the molecular structure thereof contains aromatic rings, heterocyclic rings and polycyclic compounds, forming a loose network structure connected by carbon chains or bond bridges. The solid extract formed by crystallization has a large specific surface area of ​​250-350m 2 / g (dry basis), and further washed with alkali solution to obtain liquid landfill leachate extract, which is a dark brown liquid natural organic polymer mixture with an average relative molecular weight of 500-20000, and has strong adsorption and flocculation capabilities. Therefore, the present invention obtains the landfill leachate extract in the process of treating landfill leachate, and has the concept of treating waste with waste and environmental protection, and has a significant effect in terms of economic benefits.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The present invention performs pre-treatment on landfill leachate, adopts chemical reaction, aging reaction, flocculation and other steps to obtain a solid landfill leachate extract containing organic matter such as humic acid, and further releases the organic matter in the solid landfill leachate extract through alkali treatment, elution and other steps, and further uses it in industrial wastewater treatment. Compared with the prior art, the landfill leachate extract prepared by the present invention has a large specific surface area, strong adsorption and flocculation capabilities, and can significantly improve the wastewater treatment effect; it can achieve the process treatment target in a shorter reaction time, greatly saving the treatment cost.

[0034] (2) The landfill leachate extract of the present invention reduces the difficult-to-biodegrade organic pollutants in the wastewater. Compared with the existing conventional wastewater treatment process, the present invention achieves a synergistic effect between processes in the field of industrial wastewater treatment by adding the landfill leachate extract, and the wastewater treatment efficiency is improved by more than 20%, which has good economic benefits and application prospects. DETAILED DESCRIPTION

[0035] The experimental methods in the following examples of the present invention, where no specific conditions are specified, are usually carried out under conventional conditions or under conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0036] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present invention. In addition, in the following description, the description of known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0038] Example 1 Preparation of landfill leachate extract

[0039] The steps of preparing the landfill leachate extract in this embodiment are as follows:

[0040] The landfill leachate is from the Huaihua landfill in Hunan, with a pH of 7.2 and a COD of 1066 mg / L.

[0041] S1. Filter the landfill leachate to remove suspended matter, add a certain amount of 300 g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1) to the filtrate, adjust the pH value of the filtrate to 2.5, stir rapidly at 120 r / min for 30 min, then stir slowly at 40 r / min for 60 min, further maintain slow stirring at 15 r / min for aging and crystallization reaction for 8 h, and set aside;

[0042] S2, filtering the solution obtained by aging and crystallization in step S1 to obtain a filtrate and a filter residue, wherein the specific surface area of ​​the filter residue is 320 m 2 / g (dry basis);

[0043] S3. Add a 50 g / L sodium hydroxide aqueous solution to the filter residue of step S2 for elution. The solution generated after elution is further used to elute the filter residue (the elution is repeated 3 to 5 times) to allow it to react fully. The eluent obtained after the reaction is a landfill leachate extract, and the average relative molecular weight of the landfill leachate extract is 12,000.

[0044] Application Example 1: Treatment of printing and dyeing wastewater

[0045] The landfill leachate extract prepared in Example 1 was used to treat printing and dyeing wastewater, with the printing and dyeing wastewater from Huizhou, Guangdong as the treatment object. The pH of the raw water was 6.8, and the COD was 670 mg / L.

[0046] The specific processing steps are:

[0047] (1) Add the landfill leachate extract prepared in Example 1 to the printing and dyeing wastewater to be treated (add 0.6 mL of landfill leachate extract per liter of filtrate), adjust the pH value of the printing and dyeing wastewater to 2.0 with a dilute sulfuric acid aqueous solution (concentration of 300 g / L), and stir the reaction for 20 minutes;

[0048] (2) filtering the solution after the reaction in step (1) to obtain a filtrate and a filter residue;

[0049] (3) The filtrate obtained in step (2) is sent to a micro-electrolysis catalytic reactor, and the reaction pH is 1.0 to 4.0 (the pH of the filtrate is completely matched with the micro-electrolysis catalytic reaction system, so there is no need to adjust the pH in this step), and the wastewater is further reacted in the micro-electrolysis catalytic reactor for 40 minutes. After the reaction is completed, aeration treatment is performed, and then the pH is adjusted to 8.0 to 8.5 for flocculation and precipitation treatment. The treated liquid enters the next process to continue to complete the wastewater treatment normally (ozone catalytic oxidation deep treatment system);

[0050] (4) The filter residue obtained in step (2) is disposed of in a normal discharge yard.

[0051] (5) The treated liquid in step (2) is introduced into an ozone catalytic oxidation system for deep oxidation treatment for 50 minutes to achieve a COD emission standard of less than 100 mg / L.

[0052] Comparative application example 1: Conventional treatment of printing and dyeing wastewater

[0053] The printing and dyeing wastewater from Huizhou, Guangdong was taken as the treatment object. The pH of the raw water was 6.8 and the COD was 670 mg / L.

[0054] The specific processing steps are:

[0055] (1) In the printing and dyeing wastewater to be treated, the pH value of the landfill leachate is adjusted to 2.2 with a dilute sulfuric acid aqueous solution (300 g / L);

[0056] (2) The treated liquid obtained in step (1) is sent to a micro-electrolysis catalytic reactor for reaction for 40 minutes, and then enters the air aeration tower for air aeration for 30 minutes, and then the pH is adjusted to 8.0-8.5, and a flocculant PAC (polyaluminum chloride, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.) is added at an amount of 60 mg / L, and the mixture is quickly stirred evenly. A coagulant aid PAM (polyacrylamide, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.) is added at an amount of 10 mg / L, and the mixture is stirred evenly. The mixture is flocculated and precipitated, and filter-filtered to obtain a treated filtrate. The treated filtrate is tested and entered into the next step to continue to normally complete the wastewater treatment (ozone catalytic oxidation deep treatment system).

[0057] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 1 and comparative application example 1

[0058] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater in Example 1 and Comparative Application Example 1 were tested. The specific determination methods are as follows:

[0059] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0060] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0061] Wastewater color: visual comparison;

[0062] The results obtained by the above determination method are shown in Table 1;

[0063] Table 1: Results of effluent treatment of printing and dyeing wastewater

[0064]

[0065] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0066] By comparing Application Example 1 and Comparative Application Example 1, it can be seen from the results in Table 1 that the treatment of printing and dyeing wastewater by adding landfill leachate extract is better than that of conventional wastewater treatment process (without adding landfill leachate extract), and the COD in the final effluent is lower, and the COD removal rate exceeds 70%. The COD removal rate of Application Example 1 is 23.2% higher than that of Comparative Application Example 1, and part of the color of the printing and dyeing wastewater is removed at the same time; the COD value of the effluent of the ozone catalytic oxidation deep treatment system is lower than 100 mg / L in Application Example 1, which meets the emission standards; while the COD value of Comparative Application Example 1 is 169 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 130 minutes.

[0067] Example 2 Preparation of landfill leachate extract

[0068] The steps of preparing the landfill leachate extract in this embodiment are as follows:

[0069] The landfill leachate is from the Huaihua landfill in Hunan, with a pH of 7.2 and a COD of 1066 mg / L.

[0070] S1, the landfill leachate was filtered to remove suspended matter, a certain amount of 300g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA was 94:3.9:2:0.1) was added to the filtrate to adjust the pH value of the filtrate to 2.0, and the mixture was rapidly stirred at 140r / min for 30min, then slowly stirred at 60r / min for 120min, and further maintained at a slow stirring speed of 20r / min for aging and crystallization reaction for 5.5h, and then used for standby;

[0071] S2, filtering the solution after aging and crystallization in step S1 to obtain a filtrate and a filter residue, wherein the specific surface area of ​​the filter residue is 295m 2 / g (dry basis);

[0072] S3. Add a 50 g / L sodium hydroxide aqueous solution to the filter residue of step S2 for elution. The solution generated after elution is further used to elute the filter residue (the elution is repeated 3 to 5 times) to allow it to react fully. The eluent obtained after the reaction is a landfill leachate extract, and the average relative molecular weight of the landfill leachate extract is 8900.

[0073] Application Example 2: Treatment of Printing and Dyeing Wastewater with Leachate Extract

[0074] The landfill leachate extract prepared in Example 2 was used to treat printing and dyeing wastewater, with the printing and dyeing wastewater from Huizhou, Guangdong as the treatment object. The pH of the raw water was 6.8, and the COD was 670 mg / L.

[0075] The specific governance steps are:

[0076] (1) Add the landfill leachate extract prepared in Example 2 to the printing and dyeing wastewater to be treated (1.2 mL of landfill leachate extract per liter of filtrate), adjust the pH value of the printing and dyeing wastewater to 2.0 with a dilute sulfuric acid aqueous solution (concentration of 300 g / L), and stir the reaction for 20 minutes;

[0077] (2) filtering the solution after the reaction in step (1) to obtain a filtrate and a filter residue;

[0078] (3) The filtrate obtained in step (2) is sent to a micro-electrolysis catalytic reactor, and the reaction pH is 1.0 to 4.0 (the pH of the filtrate is completely matched with the micro-electrolysis catalytic reaction system, so there is no need to adjust the pH in this step), and the wastewater is further reacted in the micro-electrolysis catalytic reactor for 40 minutes. After the reaction is completed, aeration treatment is performed, and then the pH is adjusted to 8.0 to 8.5 for flocculation and precipitation treatment. The treated liquid enters the next process to continue to complete the wastewater treatment normally (ozone catalytic oxidation deep treatment system);

[0079] (4) The filter residue obtained in step (2) is disposed of in a normal discharge yard.

[0080] (5) The treated liquid in step (2) is introduced into an ozone catalytic oxidation system for deep oxidation treatment for 50 minutes to achieve a COD emission standard of less than 100 mg / L.

[0081] Comparative Application Example 2: Conventional Treatment of Printing and Dyeing Wastewater

[0082] The printing and dyeing wastewater from Huizhou, Guangdong was taken as the treatment object. The pH of the raw water was 6.8 and the COD was 670 mg / L.

[0083] The specific processing steps are:

[0084] (1) In the printing and dyeing wastewater to be treated, the pH value of the landfill leachate containing the landfill leachate extract is adjusted to 2.0 with a 300 g / L dilute sulfuric acid aqueous solution;

[0085] (2) The treated liquid obtained in step (1) is sent to a micro-electrolysis catalytic reactor for reaction for 40 minutes; then it is sent to an air aeration tower for 30 minutes, and then the pH is adjusted to 8.0-8.5, and a flocculant PAC (polyaluminum chloride, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.) is added at an amount of 60 mg / L, and the mixture is quickly stirred evenly. A coagulant aid PAM (polyacrylamide, purchased from Henan Qianyuexing Chemical Technology Co., Ltd.) is added at an amount of 10 mg / L, and the mixture is stirred evenly. The mixture is flocculated and precipitated, and filter-filtered to obtain a treated filtrate. The treated filtrate is tested and the mixture is sent to the next step to continue to normally complete the wastewater treatment (ozone catalytic oxidation deep treatment system).

[0086] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 2 and comparative application example 2

[0087] The COD, pH value and wastewater odor of the final effluent of the printing and dyeing wastewater in Application Example 2 and Comparative Application Example 2 were tested. The specific determination methods are as follows:

[0088] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0089] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0090] Wastewater color: visual comparison;

[0091] The results obtained by the above determination method are shown in Table 2;

[0092] Table 2: Final effluent results of printing and dyeing wastewater treatment

[0093]

[0094] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0095] By comparing Application Example 2 and Comparative Application Example 2, it can be seen from the results in Table 2 that the treatment process of printing and dyeing wastewater with the addition of landfill leachate extract is better than the conventional wastewater treatment process (without adding landfill leachate extract), and the COD in the final effluent is lower, and the COD removal rate exceeds 70%, which is 22.6% higher than the COD removal rate of Comparative Test Example 4, and part of the color of the printing and dyeing wastewater is removed at the same time; the COD value of the effluent of the ozone catalytic oxidation deep treatment system is lower than 100 mg / L in Application Example 2, which meets the emission standards; while the COD value of Comparative Application Example 2 is 164 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 125 min.

[0096] Comparative Example 1 Preparation of landfill leachate extract (pH below 1.5)

[0097] When preparing the landfill leachate extract, an excess amount of an aqueous solution of an extractant having a concentration of 300 g / L (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA being 94:3.9:2:0.1) was added to the landfill leachate (consistent with Example 1) to adjust the pH value of the filtrate to 1.0, and the other steps were consistent with Example 1.

[0098] The specific surface area of ​​the filter residue obtained in step S2 is 180 m 2 / g (dry basis), the average relative molecular weight of the landfill leachate extract obtained in step S3 is 5500.

[0099] Application Example 3

[0100] The operation is consistent with that of Application Example 1.

[0101] Comparative Application Example 3

[0102] The operation is consistent with that of comparative application example 1.

[0103] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 3 and comparative application example 3

[0104] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater in Example 3 and Comparative Application Example 3 were tested. The specific determination methods are as follows:

[0105] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0106] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0107] Wastewater color: visual comparison;

[0108] The results obtained by the above determination method are shown in Table 3;

[0109] Table 3: Results of effluent treatment of printing and dyeing wastewater

[0110]

[0111] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0112] Through the comparison between Application Example 3 and Comparative Application Example 3, it can be seen from the results in Table 3 that the COD removal rate of Application Example 3 is not significantly improved compared with Comparative Application Example 3 (less than 10%); the COD value of the effluent from the ozone catalytic oxidation deep treatment system is 142 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 110 minutes.

[0113] Comparative Example 2 Preparation of landfill leachate extract (pH exceeds 3.0)

[0114] When preparing the landfill leachate extract, a small amount of 300 g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1) is added to the landfill leachate (consistent with Example 1) to adjust the pH value of the filtrate to 5.5, and the other parameters are consistent with Example 1.

[0115] The specific surface area of ​​the filter residue obtained in step S2 is 110 m 2 / g (dry basis), the average relative molecular weight of the landfill leachate extract obtained in step S3 is lower than 2500.

[0116] Application Example 4

[0117] The pH value of the filtrate entering the micro-electrolysis catalytic reactor was adjusted to 2.5, and the other operations were the same as those in Application Example 1, wherein the specific surface area of ​​the filter residue obtained in step S2 was 65 m 2 / g (dry basis), the average relative molecular weight of the landfill leachate extract obtained in step S3 is about 3800.

[0118] Comparative Application Example 4

[0119] The operation is consistent with that of comparative application example 1.

[0120] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 4 and comparative application example 4

[0121] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater of Example 4 and Comparative Application Example 4 were tested. The specific determination methods are as follows:

[0122] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0123] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0124] Wastewater color: visual comparison;

[0125] The results obtained by the above determination method are shown in Table 4;

[0126] Table 4: Results of effluent treatment of printing and dyeing wastewater

[0127]

[0128] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0129] By comparing Application Example 4 and Comparative Application Example 4, it can be seen from the results in Table 4 that the COD removal rate of Application Example 4 is not significantly improved compared with Comparative Application Example 4 (less than 10%); the COD value of the effluent from the ozone catalytic oxidation deep treatment system is 150 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 120 min.

[0130] Comparative Example 3 Preparation of landfill leachate extract (slow stirring omitted)

[0131] The difference between this comparative example and Example 1 is that the step S1 of preparing the landfill leachate extract is different, specifically:

[0132] S1. Filter the landfill leachate to remove suspended matter, add a certain amount of 300 g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1) to the landfill leachate (consistent with Example 1), adjust the pH value of the filtrate to 2.5, stir rapidly at 120 r / min for 30 min, further maintain slow stirring at 15 r / min for aging and crystallization for 8 h, and set aside.

[0133] The other steps are consistent with those in Example 1;

[0134] The specific surface area of ​​the filter residue obtained in step S2 is 175 m 2 / g (dry basis), and the average relative molecular weight of the landfill leachate extract obtained in step S3 is 9500.

[0135] Application Example 5

[0136] The operation is consistent with that of Application Example 1.

[0137] Comparative Application Example 5

[0138] The operation is consistent with that of comparative application example 1.

[0139] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 5 and comparative application example 5

[0140] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater in Example 5 and Comparative Application 5 were tested. The specific determination methods are as follows:

[0141] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0142] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0143] Wastewater color: visual comparison;

[0144] The results obtained by the above determination method are shown in Table 5;

[0145] Table 5: Results of effluent treatment of printing and dyeing wastewater

[0146]

[0147] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0148] Through the comparison between Application Example 5 and Comparative Application Example 5, it can be seen from the results in Table 5 that the COD removal rate of Application Example 5 is not significantly improved compared with Comparative Application Example 5 (less than 10%); the COD value of the effluent from the ozone catalytic oxidation deep treatment system is 155 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 125 min.

[0149] Comparative Example 4 Preparation of landfill leachate extract (rapid stirring omitted)

[0150] The difference between this comparative example and Example 1 is that the step S1 of preparing the landfill leachate extract is different, specifically:

[0151] S1, filtering the landfill leachate to remove suspended matter, adding a certain amount of 300 g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1) to the landfill leachate (consistent with Example 1), adjusting the pH value of the filtrate to 2.5, stirring slowly at 40 r / min for 60 min, further maintaining slow stirring at 15 r / min for aging and crystallization for 8 h, and setting aside;

[0152] The other steps are consistent with those in Example 1;

[0153] The specific surface area of ​​the filter residue obtained in step S2 is 85 m 2 / g (dry basis), the average relative molecular weight of the landfill leachate extract obtained in step S3 is 7500.

[0154] Application Example 6

[0155] The operation is consistent with that of Application Example 1.

[0156] Comparative Application Example 6

[0157] The operation is consistent with that of comparative application example 1.

[0158] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 6 and comparative application example 6

[0159] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater of Example 6 and Comparative Application Example 6 were tested. The specific determination methods are as follows:

[0160] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0161] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0162] Wastewater color: visual comparison;

[0163] The results obtained by the above determination method are shown in Table 6;

[0164] Table 6: Results of effluent treatment of printing and dyeing wastewater

[0165]

[0166]

[0167] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0168] By comparing Application Example 6 and Comparative Test Example 6, it can be seen from the results of Table 7 that the COD removal rate of Application Example 6 is not significantly improved compared with Comparative Application Example 6 (less than 10%); the COD value of the effluent from the ozone catalytic oxidation deep treatment system is 146 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 115 min.

[0169] Comparative Example 5 Preparation of landfill leachate extract (aging and crystallization omitted)

[0170] The difference between this comparative example and Example 1 is that the step S1 of preparing the landfill leachate extract is different, specifically:

[0171] S1, filtering the landfill leachate to remove suspended matter, adding a certain amount of 300 g / L aqueous extractant solution (the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 94:3.9:2:0.1) to the landfill leachate (consistent with Example 1), adjusting the pH value of the filtrate to 2.5, rapidly stirring at 120 r / min for 30 min, then slowly stirring at 40 r / min for 60 min, without aging and crystallization reaction, and set aside;

[0172] The other steps are consistent with those in Example 1;

[0173] The specific surface area of ​​the filter residue obtained in step S2 is 55m 2 / g (dry basis), the average relative molecular weight of the landfill leachate extract obtained in step S3 is less than 500.

[0174] Application Example 7

[0175] The operation is consistent with that of Application Example 1.

[0176] Comparative Application Example 7

[0177] The operation is consistent with that of comparative application example 1.

[0178] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 7 and comparative application example 7

[0179] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater in Example 7 and Comparative Application Example 7 were tested. The specific determination methods are as follows:

[0180] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0181] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0182] Wastewater color: visual comparison;

[0183] The results obtained by the above determination method are shown in Table 7;

[0184] Table 7: Results of effluent treatment of printing and dyeing wastewater

[0185]

[0186] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0187] Through the comparison between Application Example 7 and Comparative Application Example 7, it can be seen from the results in Table 7 that the COD removal rate of Application Example 7 is not significantly improved compared with Comparative Application Example 7 (less than 10%); the COD value of the effluent from the ozone catalytic oxidation deep treatment system is 158 mg / L, which cannot meet the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be achieved, the reaction time needs to be increased to 120 min.

[0188] In summary, according to Application Examples 5 to 7, it can be seen that in the preparation process of landfill leachate extract, rapid stirring, slow stirring and aging crystallization are indispensable. The comparative example 5 omits the aging crystallization step, and the prepared landfill leachate extract wastewater treatment effect is not good. The main reason may be that the reaction of fine crystals to form coarse crystals is insufficient, which reduces the crystal specific surface area of ​​natural high-molecular organic mixtures containing humic acid and fulvic acid, and the effect is significantly reduced; the effluent of the ozone catalytic oxidation deep treatment system, Application Examples 3 to 7 and Comparative Application Example 7 are all higher than the effluent requirement of 100 mg / L. If the effluent requirement of 100 mg / L is to be met, the reaction time needs to be increased to 100-130 min.

[0189] Comparative Example 6 Preparation of Leachate Extract (Different Extractants)

[0190] The difference between this comparative example and Example 1 is that the aqueous extractant solution in step S1 of preparing the landfill leachate extract is different.

[0191] The extractant aqueous solution of this comparative example is: the concentration of the extractant aqueous solution is 300g / L, and the mass ratio of sulfuric acid, tartaric acid, adipic acid and ED is 88:5.9:5:0.1;

[0192] A certain amount of the above-mentioned aqueous extractant solution was added to the landfill leachate (consistent with Example 1) to adjust the pH value of the filtrate to 2.5. Other operations were consistent with Example 1.

[0193] The specific surface area of ​​the final filter residue is 318m 2 / g (dry basis); the average relative molecular weight of the leachate extract is 11600.

[0194] Application Example 8

[0195] The operation is consistent with that of Application Example 1.

[0196] Comparative Application Example 8

[0197] The operation is consistent with that of comparative application example 1.

[0198] Determination and analysis of the treatment effect of printing and dyeing wastewater in application example 8 and comparative application example 8

[0199] The COD, pH value and wastewater color of the final effluent of the printing and dyeing wastewater of Example 8 and Comparative Application Example 8 were tested. The specific determination methods are as follows:

[0200] COD (chemical oxygen demand) determination: HJ 828-2017 Determination of chemical oxygen demand of water quality-dichromate method;

[0201] pH determination: GB 6920-86 Determination of pH value of water quality glass electrode method;

[0202] Wastewater color: visual comparison;

[0203] The results obtained by the above determination method are shown in Table 8;

[0204] Table 8: Results of effluent treatment of printing and dyeing wastewater

[0205]

[0206] Note: In the table, pre-treatment refers to the treatment process before the biochemical system; ozone system refers to the ozone catalytic oxidation deep treatment system (time 50 minutes).

[0207] Through the comparison between Application Example 8 and Comparative Application Example 8, it can be seen from the results in Table 8 that the treatment of printing and dyeing wastewater by adding landfill leachate extract is better than the conventional wastewater treatment process (without adding landfill leachate extract), and the COD in the final effluent is lower, and the COD removal rate exceeds 70%. The COD removal rate of Test Example 8 is 22.6% higher than that of Comparative Test Example 8, and part of the color of the printing and dyeing wastewater is removed at the same time; the COD value of the effluent of the ozone catalytic oxidation deep treatment system is lower than 100mg / L in Application Example 8, which meets the emission standards; while the COD value of Comparative Application Example 8 is 169mg / L, which cannot meet the effluent requirement of 100mg / L. If the effluent requirement of 100mg / L is to be achieved, the reaction time needs to be increased to 130min. It is worth noting that due to the change in the composition of the extractant, the filtration operation during extraction is more difficult, which affects the work efficiency and operating cost, but has no obvious effect on the final experimental data.

[0208] Based on the above embodiments, test examples and comparative experimental examples, the landfill leachate extract prepared under a specific range of conditions in the present invention can significantly improve the wastewater pretreatment effect and achieve a synergistic effect between processes, wherein the COD removal efficiency is increased by more than 20%, and the emission requirements can be met within a shorter reaction time. It has obvious effects in the treatment of printing and dyeing wastewater. Therefore, the technical solution of the present invention is very suitable for the treatment of various industrial wastewaters.

[0209] Obviously, the above embodiments are merely examples for the purpose of clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived therefrom are still within the scope of protection of the invention.

Claims

1. A method for preparing a landfill leachate extract, characterized in that: The steps include: S1, filtering the landfill leachate, adding an extractant to adjust the pH value of the filtrate to no more than 3.0, stirring, aging and crystallizing, wherein the extractant is an aqueous solution containing sulfuric acid, tartaric acid, adipic acid and EDTA; S2, filtering the solution after aging and crystallization in step S1 to obtain a filtrate and a filter residue; S3, adding alkaline solution to the filter residue in step S2 for elution, and filtering the elution liquid obtained as the landfill leachate extract.

2. The method for preparing the landfill leachate extract according to claim 1, characterized in that: In step S1, the mass ratio of sulfuric acid, tartaric acid, adipic acid and EDTA is 92-96:1-5:1-3:0.05-0.5, and the concentration of the aqueous solution of the extractant is 50-300 g / L.

3. The method for preparing the landfill leachate extract according to claim 1, characterized in that: The stirring and aging crystallization procedure in step S1 is: rapid stirring at 120-150 r / min for 30-60 min, then slow stirring at 40-60 r / min for 60-120 min, and further maintaining slow stirring at 10-20 r / min for aging crystallization for 2-12 h.

4. The method for preparing the landfill leachate extract according to claim 1, characterized in that: The pH in step S1 is 1.5 to 2.

8.

5. The method for preparing the landfill leachate extract according to claim 1, characterized in that: The specific surface area of ​​the filter residue in step S2 is 250-350m 2 / g; the alkali solution in step S3 includes one or more of sodium hydroxide, potassium hydroxide, and calcium hydroxide, and the mass concentration of the alkali solution is 5 to 50 g / L.

6. A landfill leachate extract, characterized in that: The invention comprises a method for preparing the landfill leachate extract according to any one of claims 1 to 5, wherein the landfill leachate extract is a dark brown liquid with an average relative molecular weight of 500 to 20,000.

7. The use of the landfill leachate extract in wastewater treatment according to claim 6, characterized in that: The wastewater includes chemical wastewater, metallurgical wastewater, pharmaceutical wastewater, printing and dyeing wastewater, electroplating wastewater and leather wastewater.

8. The use according to claim 7, characterized in that: The application of the landfill leachate extract comprises the following steps: (1) adjusting the pH value of the wastewater to no more than 3.0 with a dilute sulfuric acid aqueous solution, and then adding the landfill leachate extract of claim 6 to react; (2) filtering the solution after the reaction in step (1) to obtain a filtrate and a filter residue; (3) The filtrate obtained in step (2) is sent to a micro-electrolysis catalytic reactor, and the wastewater is further reacted in the micro-electrolysis catalytic reactor, and the reaction pH is 1.0 to 4.0 (the pH of the filtrate is completely matched with the micro-electrolysis catalytic reaction system, so there is no need to adjust the pH in this step, which has a synergistic effect). After the reaction is completed, aeration treatment is performed, and then the pH is adjusted to 8.0 to 8.5 for flocculation and precipitation treatment. The treated liquid enters the next process to continue to complete the wastewater treatment normally; (4) disposing the filter residue obtained in step (2) into a normal discharge yard; (5) The treated liquid in step (2) is introduced into an ozone catalytic oxidation system for deep oxidation treatment for 40-60 minutes to achieve a COD emission standard of less than 100 mg / L.

9. The use according to claim 8, characterized in that: In the step (1), the dosage of the landfill leachate extract is 0.5 to 10 mL per liter of wastewater.

10. The use according to claim 8, characterized in that: The micro-electrolysis catalytic reactor in step (3) is an iron-carbon micro-electrolysis catalytic reactor, the reaction time in the micro-electrolysis catalytic reactor is 30 to 120 minutes, the aeration is air aeration, and the aeration time is 30 to 60 minutes; the flocculation and precipitation treatment includes adding 60 to 120 mg / L of flocculant and / or 5 to 30 mg / L of coagulant aid.

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