A method for treating landfill leachate membrane filtration concentrate

Abstract

The present application belongs to the technical field of landfill leachate membrane filtration concentrate treatment, and relates to a landfill leachate membrane filtration concentrate treatment method. A Ni-Al2O3 catalyst with a large specific surface area, uniform pore size distribution and uniform nickel element distribution is prepared, and the catalyst is applied to landfill leachate membrane filtration concentrate, which promotes the removal of COD in the membrane filtration concentrate, converts it into hydrogen and other gas products, promotes the degradation of aromatic ring substances and the breaking of carbon-carbon double bonds in macromolecular substances in the landfill leachate membrane filtration concentrate, is beneficial to subsequent treatment, has a significant heavy metal ion removal capacity, reduces the harmfulness of the membrane filtration concentrate, and provides a new treatment direction and idea for landfill leachate membrane filtration concentrate treatment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of landfill leachate membrane filtration concentrate treatment, more particularly relates to a landfill leachate membrane filtration concentrate treatment method. BACKGROUND

[0002] Due to the rapid increase of municipal solid waste production, the treatment of landfill leachate and membrane filtration concentrate has become one of the problems restricting the development of waste-free cities in China. Especially, membrane filtration concentrate, as the inevitable product of the effluent from the biochemical pool of landfill leachate membrane separation treatment, its treatment is a problem that must be solved in the application process of membrane treatment technology.

[0003] With the continuous improvement of the treatment and discharge requirements of landfill leachate, in order to meet the discharge standards, the combined process of biochemical method and membrane process is widely applied and studied, and the membrane filtration concentrate produced thereby has high colority, strong toxicity, high organic pollutants and low biodegradability. If not properly treated, it will cause more serious environmental problems.

[0004] Landfill leachate membrane filtration concentrate is a pollution wastewater with high COD, ammonia nitrogen and heavy metal content. At present, the treatment methods of landfill leachate membrane filtration concentrate mainly focus on the reduction and harmless treatment of organic pollutants, including transfer, reduction and harmless treatment.

[0005] The common transfer treatment is backfilling treatment, which introduces the landfill leachate membrane filtration concentrate from top to bottom into the landfill layer, and utilizes the microorganisms in the landfill to degrade the organic pollutants in the liquid, but it will pollute the groundwater. The backfilling process can only delay and change the pollution mode, but cannot properly solve the pollution caused by membrane filtration concentrate. Reduction treatment is to further reduce the membrane filtration concentrate by means of evaporation, nanofiltration, membrane distillation, ultrafiltration and other means, but the removal effect of pollutants is not good. For example, membrane distillation can achieve high distillation efficiency, but the membrane cost is high, the distillation flux is limited by the system, and the temperature change and concentration polarization will also affect the membrane distillation effect, making it difficult to maintain the stability of the running state. Membrane distillation is a process with phase change, and heat is mainly transferred to the liquid by heat conduction, so the energy conversion efficiency is low. Harmless treatment includes flocculation precipitation, advanced oxidation, incineration and other chemical and physical methods. These methods often have the problems of additional reagent addition or high cost, for example, using ozone to oxidize landfill leachate membrane filtration concentrate can effectively destroy the macromolecular organic matter in the concentrate, but there is the problem of poor economy and insufficient utilization of organic matter in the membrane filtration concentrate.

[0006] Aqueous phase reforming is a technology in which organic matter reacts with water under the action of a catalyst at a reaction temperature of 200-250 DEG C and a reaction pressure of 0-5 MPa, and hydrogen is produced by degradation of the organic matter. It has the characteristics of low energy consumption and renewable hydrogen production.

[0007] At present, the water phase reforming has been applied in the field of organic wastewater treatment with relatively simple components such as beer wastewater, cheese whey and fruit juice wastewater, but the landfill leachate membrane filtration concentrate has complex components, high concentration of organic pollutants, high content of inorganic salts and heavy metals, and low biodegradability, and there is no report that the water phase reforming is successfully applied to the landfill leachate membrane filtration concentrate.

[0008] Therefore, how to provide a landfill leachate membrane filtration concentrate treatment method, reduce the harmfulness of the membrane filtration concentrate, and fully utilize the organic matter to convert into energy material is a problem to be solved by those skilled in the art. SUMMARY

[0009] To solve the above technical problems, the present application provides a landfill leachate membrane filtration concentrate treatment method. First, a Ni-Al2O3 catalyst is prepared, which has a large specific surface area, a uniform pore size distribution, and a uniform distribution of nickel elements. The catalyst is applied to the landfill leachate membrane filtration concentrate, which promotes the removal of COD in the membrane filtration concentrate, converts it into hydrogen gas and other gas products, and promotes the rupture of carbon-carbon double bonds in macromolecular substances in the landfill leachate membrane filtration concentrate, which is beneficial to subsequent treatment. It also has a significant heavy metal ion removal capacity, reducing the harmfulness of the membrane filtration concentrate.

[0010] To achieve the above purpose, the present application provides the following technical solutions:

[0011] One of the technical solutions of the present application is to provide a preparation method of a Ni-Al2O3 catalyst, comprising:

[0012] The pseudoboehmite is calcined and then immersed in a nickel nitrate aqueous solution to obtain a mixture;

[0013] The mixture is heated and stirred to collect a solid product;

[0014] The solid product is dried and calcined to obtain a precursor product;

[0015] The precursor product is reduced to obtain the Ni-Al2O3 catalyst.

[0016] Further, the calcination temperature is 700-900℃, and the time is 1-3h.

[0017] Further, the loading amount of Ni in the Ni-Al2O3 catalyst is 15%.

[0018] Further, the heating and stirring temperature is 70-80℃, and the time is 4-6h.

[0019] Further, the drying temperature of the solid product is 100-110 DEG C, and the time is 12-24h.

[0020] Further, the drying is followed by grinding and sieving, specifically, passing through an 80-100 mesh sieve, and taking the undersize.

[0021] Further, the calcination is performed under an air atmosphere, the calcination temperature is 500-600 DEG C, and the calcination time is 2-3h.

[0022] Further, the reduction is performed under a hydrogen atmosphere, the reduction temperature is 500-600 DEG C, and the time is 1-3h.

[0023] The second technical scheme of the present application provides a Ni-Al2O3 catalyst prepared by the above method.

[0024] The Ni-Al2O3 catalyst prepared by the above method has a large specific surface area, a uniform pore size distribution, and a uniform distribution of nickel elements, which can promote the effective combination of reactants and catalytic sites and improve the degradation rate of pollutants. When an industrial Al2O3 purchased directly is used to prepare the Ni-Al2O3 catalyst, a high and uniform specific surface area cannot be achieved, and the effect of the prepared Ni-Al2O3 catalyst in the present application cannot be achieved, because a high specific surface area can promote the reaction of catalytic active sites and reactants and improve the catalytic effect.

[0025] The third technical scheme of the present application provides an application of the above Ni-Al2O3 catalyst in the treatment and resource utilization of landfill leachate membrane filtration concentrate.

[0026] The fourth technical scheme of the present application provides a treatment method of landfill leachate membrane filtration concentrate, which comprises:

[0027] The above Ni-Al2O3 catalyst is used as a water-phase reforming reaction catalyst to treat the landfill leachate membrane filtration concentrate.

[0028] Further, the method for treating the landfill leachate membrane filtration concentrate is as follows: landfill leachate membrane filtration concentrate and Ni-Al2O3 catalyst are added to a reactor, air in the reactor is discharged, a pressure of 0.1-1 MPa is maintained, the temperature is raised to 180-250 DEG C under a rotation speed of 200-400 rpm, and the treatment is completed after heat preservation for 1-4h.

[0029] Further, the method for discharging air in the reactor is to seal the reactor and use nitrogen to purge 3-5 times.

[0030] Preferably, the mass ratio of the landfill leachate membrane filtration concentrate to the Ni-Al2O3 catalyst is 100-25:1.

[0031] Preferably, the rate of temperature increase is 5-15 DEG C / min.

[0032] The treatment method can effectively remove 30-50% of the substances in the landfill leachate membrane filtration concentrate, convert them into gas products, the proportion of hydrogen in the gas products can reach 20-50%, can promote the breaking of carbon-carbon double bonds in macromolecular substances to generate small molecular substances, reduce the difficulty of subsequent treatment, and can also significantly remove heavy metal ions in the landfill leachate membrane filtration concentrate, reduce the harmfulness of the landfill leachate membrane filtration concentrate.

[0033] Compared with the prior art, the technical scheme has the following beneficial effects:

[0034] The method for treating the landfill leachate membrane filtration concentrate can degrade the complex structure of macromolecular organic pollutants in the membrane filtration concentrate into small molecular substances after the Ni-Al2O3 catalytic aqueous phase reforming treatment, and can open ring and degrade aromatic compounds, which is beneficial to subsequent degradation and conversion.

[0035] The aqueous phase reforming technology for treating the landfill leachate membrane filtration concentrate not only realizes degradation of pollutants, but also realizes conversion of pollutants into renewable energy hydrogen, and widens the treatment path of the landfill leachate membrane filtration concentrate.

[0036] Compared with the transfer, reduction and harmless treatment in the prior art, the treatment method has the advantages of simple method, low cost, and can fundamentally solve the pollution caused by the landfill leachate membrane filtration concentrate through degradation and adsorption. DETAILED DESCRIPTION

[0037] The accompanying drawings, which form a part of the present application, are intended to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The accompanying drawings should not be regarded as a limitation of the present application. In the drawings:

[0038] Figure 1 The nitrogen adsorption desorption curve of the Ni-Al2O3 catalyst prepared for Example 3.

[0039] Figure 2 The pore size distribution graph of the Ni-Al2O3 catalyst prepared for Example 3.

[0040] Figure 3 The XRD graph of the Ni-Al2O3 catalyst prepared for Example 3.

[0041] Figure 4 The concentration comparison graph of heavy metal elements in the membrane filtration concentrate before and after the catalytic aqueous phase reforming treatment of Example 3.

[0042] Figure 5A molecular weight comparison chart of the composition substances in the membrane filtration concentrated liquid before and after the catalytic aqueous phase reforming treatment of Example 3.

[0043] Figure 6 A gas composition and proportion chart generated in Examples 1-3 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be apparently and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without any creative work fall within the protection scope of the present application.

[0045] Example 1

[0046] A treatment method of the landfill leachate membrane filtration concentrated liquid:

[0047] 1) After calcining the pseudo-boehmite at 700℃ for 2h, immerse it in a nickel nitrate solution to obtain a mixture; heat and stir the mixture in a water bath at 80℃ for 6h, collect the solid product; send the solid product into an oven at 105℃ for drying for 24h, then grind and pass through an 80-mesh sieve to take the undersize; calcine the undersize in a muffle furnace at 600℃ in an air atmosphere for 2h to obtain a precursor product; finally, reduce the precursor product in a fixed bed at 600℃ in a hydrogen atmosphere for 3h to obtain a Ni-Al2O3 catalyst.

[0048] 2) Put the landfill leachate membrane filtration concentrated liquid and the Ni-Al2O3 catalyst into a batch hydrothermal reaction kettle at a mass ratio of 50:1, seal, use nitrogen to purge 3 times to expel the air in the reaction kettle, maintain a pressure of 0.5MPa, heat to 230℃ at a rotation speed of 300rpm, and keep the temperature for 1h to complete the treatment.

[0049] Example 2

[0050] A treatment method of the landfill leachate membrane filtration concentrated liquid:

[0051] Compared with Example 1, the only difference is that in step 2), the mass ratio of the landfill leachate membrane filtration concentrated liquid and the Ni-Al2O3 catalyst is 100:1.

[0052] Example 3

[0053] A treatment method of the landfill leachate membrane filtration concentrated liquid:

[0054] Compared with Example 1, the only difference is that in step 2), the mass ratio of the landfill leachate membrane filtration concentrated liquid and the Ni-Al2O3 catalyst is 25:1.

[0055] Comparative Example 1

[0056] The difference compared with Example 3 is only that the pseudo-boehmite is replaced by aluminum hydroxide.

[0057] Comparative Example 2

[0058] The difference compared with Example 1 is only that the calcination temperature of the pseudo-boehmite is 1100℃.

[0059] Test Example

[0060] 1. Gas detection

[0061] The gas composition and proportion generated by the treatment method of Examples 1-3 and Comparative Examples 1-2 are detected, and the results are shown in Table 1 and Figure 6

[0062] Table 1

[0063]

[0064] In Table 1, the results of Examples 1-3 can be seen that increasing the mass ratio of landfill leachate membrane filtration concentrate and Ni-Al2O3 catalyst helps to increase the proportion of hydrogen and reduce the proportion of carbon dioxide in the membrane filtration concentrate, which shows that the increase of the catalyst ratio promotes the breaking of the C-H bond.

[0065] In Table 1, the data comparison of Comparative Examples 1-2 and Example 3 can be seen that the carrier prepared from different raw materials and the calcination temperature of the pseudo-boehmite will affect the performance of the catalyst and the proportion of hydrogen.

[0066] 2. Treatment effect

[0067] The parameter comparison of the landfill leachate membrane filtration concentrate before and after the catalytic aqueous phase reforming treatment in Examples 1-3 and Comparative Examples 1-2 is shown in Table 2.

[0068] Table 2

[0069]

[0070] From Table 2, the data comparison of Comparative Examples 1-2 and Example 3 can be seen that the catalyst prepared by the present application has better performance in aqueous phase reforming, and the treatment result is better.

[0071] Although the data of Comparative Example 1 and Comparative Example 2 are better than Example 2, because more catalysts are added in Comparative Examples 1-2, the quantitative change causes the qualitative change, compared with the same amount of Example 3, it can be seen that the technical effect of the present application is better.

[0072] Figure 1 ​This is the nitrogen adsorption analysis curve of the Ni-Al2O3 catalyst prepared in Example 3. Figure 1 It can be seen that the adsorption curve is an IV isotherm, indicating that the catalyst contains a large number of micropores and mesopores.

[0073] Figure 2 This is the pore size distribution diagram of the Ni-Al2O3 catalyst prepared in Example 3. Figure 2 It can be seen that the Ni-Al2O3 catalyst has a microporous structure below 2 nm, and also contains a large number of mesopores of 2 to 8 nm. The overall pore size is small, providing a larger specific surface area and enhancing the ability of reactants to bind to catalytic sites.

[0074] Figure 3 The XRD pattern of Ni-Al2O3 catalyst prepared in Example 3. Figure 3 It can be seen that three obvious Ni diffraction peaks are found at 44.5°, 51.8° and 76.4°, showing the uniform loading of Ni on the support.

[0075] Figure 4 The figure is a comparison of the concentration of heavy metal elements in the membrane filtration concentrate before and after the catalytic aqueous phase reforming treatment in Example 3. Figure 4 It can be seen that the heavy metal elements are removed through the treatment of catalytic aqueous phase reforming. They may be reduced to metal elements during the reaction process and removed by filtration after the reaction.

[0076] Figure 5 The figure is a comparison of the molecular weights of the components in the membrane filtration concentrate before and after the catalytic aqueous phase reforming treatment in Example 3. Figure 5 It can be seen that after catalytic aqueous phase reforming treatment, the substances in the membrane filtration concentrate are converted into small molecular substances, demonstrating the catalyst's ability to break carbon-carbon bonds.

[0077] Figure 6 The gas composition and proportion diagrams generated in Examples 1-3 and Comparative Examples 1-2 are shown. Figure 6 It can be seen that increasing the mass ratio of landfill leachate membrane filtration concentrate and Ni-Al2O3 catalyst helps to increase the proportion of hydrogen and reduce the proportion of carbon dioxide in the membrane filtration concentrate, indicating that the increase in the catalyst ratio promotes the breaking of the CH bond. It can be seen from Comparative Examples 1-2 that the selection of raw materials for carrier preparation and the calcination temperature of pseudo-boehmite will affect the performance of the catalyst and the hydrogen ratio.

[0078] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0079] The foregoing description of the disclosed embodiments enables a person skilled in the art to make or use the application. Modifications of these embodiments will occur to persons of skill in the art, and that the appended claims are intended to cover all such modifications that do not depart from the true spirit and scope of the application. Therefore, the application is not limited to the embodiments shown but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. Application of a Ni-Al2O3 catalyst in the treatment and resource utilization of landfill leachate membrane filtration concentrate, characterized in that: The Ni-Al2O3 catalyst is used as a catalyst for aqueous phase reforming reaction, and the preparation steps include: The pseudo-boehmite is calcined and then immersed in a nickel nitrate aqueous solution to obtain a mixture; The mixture is heated and stirred, and then a solid product is collected; The solid product is dried and calcined to obtain a precursor product; The Ni-Al2O3 catalyst is obtained by reducing the precursor product; The calcination temperature is 700-900° C., and the time is 1-3 hours; the heating and stirring temperature is 70-80° C., and the time is 4-6 hours.

2. The use according to claim 1, characterized in that The solid product is dried at a temperature of 100 to 110° C. for 12 to 24 hours. After drying, the solid product is ground and sieved, specifically through an 80 to 100 mesh sieve, and the sieve residue is taken. The calcination is carried out in an air atmosphere at a temperature of 500 to 600° C. for 2 to 3 hours.

3. The use according to claim 1, characterized in that The reduction is carried out under hydrogen atmosphere, the reduction temperature is 500-600° C., and the time is 1-3 hours; the Ni loading amount in the Ni-Al 2 O 3 catalyst is 15%.

4. A method for treating landfill leachate membrane filtration concentrate, characterized in that: include: Using Ni-Al2O3 catalyst as aqueous phase reforming catalyst to treat landfill leachate membrane filtration concentrate; The preparation steps of the Ni-Al2O3 catalyst include: calcining pseudo-boehmite and then immersing it in a nickel nitrate aqueous solution to obtain a mixture; heating and stirring the mixture and then collecting a solid product; The solid product is dried and calcined to obtain a precursor product; the precursor product is reduced to obtain the Ni-Al2O3 catalyst; the calcination temperature is 700-900°C and the time is 1-3h; the heating and stirring temperature is 70-80°C and the time is 4-6h.

5. The processing method according to claim 4, characterized in that: The steps of treating the landfill leachate membrane filtration concentrate are: adding the landfill leachate membrane filtration concentrate and the Ni-Al2O3 catalyst into the reactor, exhausting the air in the reactor, maintaining a pressure of 0.1 to 1 MPa, heating to 180 to 250° C. at a rotation speed of 200 to 400 rpm, and maintaining the temperature for 1 to 4 hours to complete the treatment.

6. The processing method according to claim 5, characterized in that: The mass ratio of the landfill leachate membrane filtration concentrate to the Ni-Al2O3 catalyst is 100 to 25:

1.

7. The processing method according to claim 5, characterized in that The heating rate is 5-15°C / min.

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