A method for disposing landfill leachate based on coal water slurry gasification

Abstract

The application discloses a landfill leachate treatment method based on coal water slurry gasification, which comprises the following steps: landfill leachate pretreatment, mixed coal powder preparation, composite coal water slurry preparation and gasification. The application has the beneficial effects that the viscosity, concentration, stability and heat value of the coal water slurry prepared under certain conditions reach the requirements of industrial coal water slurry. The composite coal water slurry is subjected to gasification reaction, the organic pollutants in the landfill leachate are subjected to thermochemical reaction, carbon and gas are formed and are high-valued, and the heavy metals in the landfill leachate are effectively solidified by chelation with the carbon. Compared with the original landfill leachate, the COD, ammonia nitrogen, total phosphorus, total nitrogen and turbidity in the obtained liquid phase product are greatly reduced, and the pH is reduced to below 9.0. The toxic and harmful components in the landfill leachate are stably and safely disposed, and a large amount of water resources is saved, and the obtained liquid phase product can be recycled to a coal water slurry preparation unit for secondary utilization.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of environmental protection, and particularly relates to a waste leachate disposal method based on coal water slurry gasification. BACKGROUND

[0002] The waste leachate refers to the water formed by the water in the garbage itself, the rain and snow water infiltrating the ground, and the garbage layer and the soil layer, containing a large amount of suspended solids and high-concentration organic and inorganic components. The organic pollutants in the waste leachate mainly include organic heterocyclic compounds (heterocyclic, polycyclic aromatic hydrocarbons), acid lipids, amides, etc., accounting for more than 70% of the total organic components of the waste leachate; the inorganic pollutants include a large amount of inorganic salts, heavy metals, ammonia nitrogen, and other refractory pollutants. The waste leachate has the characteristics of complex water quality, large water quality and quantity fluctuation, serious odor, high concentration of refractory organic matter, high ammonia nitrogen content, high heavy metal content, low biodegradability, unbalanced nutrient element ratio, high color, and if not properly treated, it is easy to cause pollution of groundwater, surface water and soil, and cause great harm to the environment and human body. The waste leachate has large water quality and quantity fluctuation, high pollutant concentration and complex types, and poor biodegradability, so it is difficult to treat. The coal water slurry, which is a coal-based liquid fuel rising in the 1970s, is composed of 60% to 75% coal, 25% to 40% water, and about 1% additives, is a black slurry that can be burned, has good fluidity and stability, is easy to store, can be atomized and burned, is a clean energy with high combustion efficiency and low pollution, can replace heavy oil fuel, and can alleviate the problem of oil energy shortage. However, the research on the coupling utilization of waste leachate disposal and coal water slurry gasification is still in the blank. SUMMARY

[0003] This section is intended to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification of the present application to avoid obscuring the purpose of this section, the abstract and the title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0004] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0005] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art, and to provide a waste leachate disposal method based on coal water slurry gasification.

[0006] To solve the above technical problems, the present application provides the following technical scheme: a waste leachate disposal method based on coal water slurry gasification, comprising the following steps:

[0007] Pretreatment of waste leachate: the waste leachate is concentrated to obtain a concentrated liquid;

[0008] Preparation of mixed coal powder: grinding coal powder to different particle sizes and mixing;

[0009] Preparation of composite coal water slurry: mixing concentrated liquid, mixed coal powder and sodium lignosulfonate and stirring to obtain the composite coal water slurry;

[0010] Gasification: gasifying the composite coal water slurry in a CO2 / H2O atmosphere to obtain high-value fuel gas, activated carbon and liquid products.

[0011] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, the COD of the liquid product is reduced by 75%, the ammonia nitrogen is reduced by 60%, the total phosphorus is reduced by 68%, the total nitrogen is reduced by 50%, and the turbidity is reduced by 51% compared with the concentrated liquid.

[0012] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, the COD of the liquid product is reduced by 80%, the ammonia nitrogen is reduced by 64%, the total phosphorus is reduced by 98%, the total nitrogen is reduced by 55%, and the turbidity is reduced by 61% compared with the concentrated liquid.

[0013] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, in the waste leachate pretreatment, the waste leachate is concentrated by 10 times by a reverse osmosis membrane.

[0014] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, in the preparation of mixed coal powder, the grinding is to 100 mesh, 200 mesh, and then mixed.

[0015] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, in the preparation of composite coal water slurry, 34.5-38.5% of the waste leachate, 0.5% of the sodium lignosulfonate, and 61-65% of the mixed coal powder are mixed according to weight.

[0016] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, in the preparation of composite coal water slurry, 34.5-36.5% of the waste leachate, 0.5% of the sodium lignosulfonate, and 63-65% of the mixed coal powder are mixed according to weight.

[0017] As a preferred scheme of the waste leachate treatment method based on coal water slurry gasification, the gasification is carried out at 800-1100℃ in a CO2 / H2O atmosphere.

[0018] As a preferred scheme of the garbage leachate treatment method based on the coal water slurry gasification, the gasification is carried out at 900 DEG C with the composite coal water slurry at 100 mL / min and water at 1.0 mL / min.

[0019] As a preferred scheme of the garbage leachate treatment method based on the coal water slurry gasification, the fuel heat value of the composite coal water slurry is greater than or equal to 20 MJ / kg.

[0020] The garbage leachate treatment method based on the coal water slurry gasification has the following advantages: the viscosity of the prepared coal water slurry is less than 1000 mPa s, the concentration is greater than 60%, the stability is greater than 99.5%, and the heat value is greater than 20 MJ / kg, which meets the requirements of industrial coal water slurry. The organic pollutants in the garbage leachate are subjected to thermochemical reaction to form carbon and gas, which are high-value utilization, and the heavy metals in the garbage leachate are effectively solidified by chelation with the carbon. Compared with the original garbage leachate, the COD in the obtained liquid product is reduced by 80%, the ammonia nitrogen is reduced by 64%, the total phosphorus is reduced by 98%, the total nitrogen is reduced by 55%, the turbidity is reduced by 61%, and the pH is less than 9.0. The toxic and harmful components in the garbage leachate are stably and safely disposed, and a large amount of water resources are saved. The obtained liquid product can be recycled to the coal water slurry preparation unit for secondary utilization. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative labor. Among them:

[0022] Figure 1 The flow chart for preparing high-value fuel gas for the embodiments of the present application. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned purposes, features and advantages of the present application more apparent and easy to understand, the specific embodiments of the present application will be described in detail in the following with reference to the embodiment description.

[0024] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited to the specific embodiments disclosed below.

[0025] Second, the "one embodiment" or "an embodiment" referred to herein can include a particular feature, structure, or characteristic. The various embodiments are not mutually exclusive, but a single embodiment can be selected from a plurality of mutually exclusive or alternative embodiments.

[0026] The landfill leachate in the present application is a landfill leachate taken from a landfill incineration power plant in the north of Jiangsu, and the concentrated liquid concentrated by 10 times of permeation-reverse osmosis membrane.

[0027] Example 1

[0028] The preparation of the finished product is carried out according to the following steps:

[0029] The coal powder is ground to 100 mesh and 200 mesh respectively, and the 100 mesh coal powder is mixed with the 200 mesh coal powder at a mass ratio of 6:4 to prepare a mixed coal powder;

[0030] The concentrated landfill leachate, the mixed coal powder of 100 mesh and 200 mesh, and the wood sodium lignosulfonate are uniformly mixed at a ratio of 34.5-38:62-65:0-0.5 to prepare a slurry. The slurry is prepared by mechanical stirring at a stirring rate of 200-300 r / min, and the stability, viscosity, and solid content are used to characterize the slurry properties, and the calorific value is used as an index to characterize the performance of the composite coal water slurry;

[0031] The gasification is carried out at a CO2 flow rate of 100 mL / min, with water being introduced at a rate of 1.0 mL / min, under a CO2 / H2O atmosphere, at a temperature of 800-1100℃, to obtain high-value fuel gas, activated carbon, and liquid phase products.

[0032] The specific parameters of the present embodiment are as follows:

[0033] According to the mass, 35.5% of the landfill leachate is mixed with 0.5% of the sodium lignosulfonate and 64% of the mixed coal powder, and then stirred in a DW-2 multifunctional electric stirrer at a stirring rate of 200-300 r / min for 20 min and static for 3 min to obtain a landfill leachate composite coal water slurry. The calorific value of the prepared composite coal water slurry fuel is 22.32 MJ / kg, the solid content is 62%, the viscosity is 996 mPa·s, and the stability is 99.87%, which is better than some of the traditional coal water slurry. The gasification is carried out at a CO2 flow rate of 100 mL / min, with water being introduced at a rate of 1.0 mL / min, under a CO2 / H2O atmosphere, at a temperature of 900℃, to obtain high-value fuel gas, activated carbon, and liquid phase products. Compared with the original landfill leachate, the COD in the obtained liquid phase product is reduced by 80%, the ammonia nitrogen is reduced by 64%, the total phosphorus is reduced by 98%, the total nitrogen is reduced by 55%, the turbidity is reduced by 61%, and the pH is 8.9.

[0034] Example 2

[0035] This example is basically the same as Example 1, the only difference is that:

[0036] According to the mass, 36.5% of the landfill leachate is mixed with 0.5% of sodium lignosulfonate and 63% of mixed coal powder;

[0037] The obtained composite coal water slurry fuel has a heat value of 20.09 MJ / kg, a solid content of 60.5%, a viscosity of 868 mPa·s, and a stability of 99.27%, and some indexes are better than those of traditional coal water slurry. In the CO2 / H2O atmosphere, the gasification is carried out at 900℃, and high-value fuel gas, activated carbon and liquid phase products are obtained. Compared with the original landfill leachate, the COD in the obtained liquid phase product is reduced by 75%, the ammonia nitrogen is reduced by 60%, the total phosphorus is reduced by 98%, the total nitrogen is reduced by 50%, the turbidity is reduced by 51%, and the pH is 8.9.

[0038] Example 3

[0039] This example is basically the same as Example 1, the only difference is that:

[0040] According to the mass, 34.5% of the landfill leachate is mixed with 0.5% of sodium lignosulfonate and 65% of mixed coal powder;

[0041] The prepared composite coal water slurry fuel has a heat value of 23.15 MJ / kg, a viscosity of 1132 mPa·s, a solid content of 62.5%, and a stability of 99.87%, and some indexes are better than those of traditional coal water slurry. In the CO2 / H2O atmosphere, the gasification is carried out at 900℃, and high-value fuel gas, activated carbon and liquid phase products are obtained. Compared with the original landfill leachate, the COD in the obtained liquid phase product is reduced by 78%, the ammonia nitrogen is reduced by 65%, the total phosphorus is reduced by 99%, the total nitrogen is reduced by 56%, the turbidity is reduced by 63%, and the pH is 8.5.

[0042] Example 4

[0043] This example is basically the same as Example 1, the only difference is that:

[0044] According to the mass, 38% of the landfill leachate is mixed with 0.5% of sodium lignosulfonate and 61.5% of mixed coal powder;

[0045] The prepared composite coal water slurry fuel has a heat value of 19.43 MJ / kg, a viscosity of 856 mPa·s, a solid content of 60%, and a stability of 98.94%. In the process of gasification, CO2 flows at 100 mL / min, and water flows at 1.0 mL / min. The gasification is carried out under the CO2 / H2O atmosphere at 900℃, and high-value fuel gas, activated carbon, and liquid phase products are obtained. Compared with the original landfill leachate, the COD of the obtained liquid phase product is reduced by 85%, the ammonia nitrogen is reduced by 68%, the total phosphorus is reduced by 99%, the total nitrogen is reduced by 60%, the turbidity is reduced by 68%, and the pH is 8.6.

[0046] Example 5

[0047] This example is basically the same as Example 1, the only difference is that:

[0048] When the liquid phase product is mixed with sodium lignosulfonate and mixed coal powder, there is a difference in mass ratio:

[0049] The liquid phase product is recycled to the coal water slurry preparation unit, and 38.5% of the liquid phase product is mixed with 0.5% of sodium lignosulfonate and 61% of mixed coal powder to prepare a coal water slurry. The prepared composite coal water slurry fuel has a heat value of 19.15 MJ / kg, a solid content of 59%, a viscosity of 789 mPa·s, and a stability of 98.87%. Under the gasification conditions at 900℃, compared with the original landfill leachate, the COD of the obtained liquid phase product is reduced by 90%, the ammonia nitrogen is reduced by 68%, the total phosphorus is reduced by 99%, the total nitrogen is reduced by 65%, the turbidity is reduced by 75%, and the pH is 8.5.

[0050] From the data in Examples 1-5, it can be seen that the proportions of landfill leachate, sodium lignosulfonate, and mixed coal powder are relatively free, and the preparation of the finished product can be carried out within a relatively wide range of raw material proportions. And about 34-36% of the mixing ratio can prepare a composite coal water slurry with high heat value, moderate viscosity, and good stability. The coal water slurry meets the standard of industrial coal water slurry, and some of its performance is better than that of industrial coal water slurry.

[0051] Example 6

[0052] This example is basically the same as Example 1, the only difference is that:

[0053] The temperature used in the gasification process is different, and the temperature during gasification is 800℃;

[0054] The high-value fuel gas, activated carbon and liquid phase product are obtained by gasification under the CO2 / H2O atmosphere at the above temperature conditions. Compared with the original landfill leachate, the COD in the obtained liquid phase product is reduced by 75%, the ammonia nitrogen is reduced by 60%, the total phosphorus is reduced by 96%, the total nitrogen is reduced by 50%, the turbidity is reduced by 54%, and the pH = 8.0.

[0055] Example 7

[0056] This example is basically the same as Example 1, the only difference is that:

[0057] The temperature used in the gasification process is different, the temperature during gasification is 1100℃;

[0058] The high-value fuel gas, activated carbon and liquid phase product are obtained by gasification under the CO2 / H2O atmosphere at the above temperature conditions. Compared with the original landfill leachate, the COD in the obtained liquid phase product is reduced by 82%, the ammonia nitrogen is reduced by 65%, the total phosphorus is reduced by 99%, the total nitrogen is reduced by 56%, the turbidity is reduced by 63%, and the pH = 8.8.

[0059] From the data in Examples 1 and 5, 6, it can be seen that the temperature during gasification can be used for processing at 800-1100℃, which can adapt to the requirements of various temperatures and processing equipment. Because of the increasing trend of fuel and performance required by the increase of gasification temperature, 900℃ is selected as the preferred processing temperature during gasification.

[0060] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limited. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

[0061] It should be noted that the above examples are only used to illustrate the technical solutions of the present application and are not limited. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A method for disposing of landfill leachate based on coal water slurry gasification, characterized by: The method comprises the following steps: The garbage leachate is pretreated by concentration to obtain concentrated liquid; The coal powder is ground and mixed with coal powder of different particle sizes to prepare mixed coal powder; The concentrated liquid, mixed coal powder and sodium lignosulfonate are mixed and stirred to prepare composite coal water slurry; The composite coal water slurry is gasified in a CO2 / H2O atmosphere to obtain high-value fuel gas, activated carbon and liquid phase products; In the preparation of the composite coal water slurry, 34.5-38.5% of the garbage leachate, 0.5% of the sodium lignosulfonate and 61-65% of the mixed coal powder are mixed by weight, or In the preparation of the composite coal water slurry, 34.5-36.5% of the garbage leachate, 0.5% of the sodium lignosulfonate and 63-65% of the mixed coal powder are mixed by weight. The gasification of the composite coal water slurry is carried out at 900℃ under the conditions of a CO2 flow rate of 100 mL / min and a water flow rate of 1.0 mL / min. The organic pollutants in the garbage leachate are subjected to a thermochemical reaction to form carbon and gas, which are high-value utilization, and the heavy metals in the garbage leachate are effectively solidified by chelation with the carbon.

2. The water coal slurry gasification based leachate disposal method according to claim 1, characterized in that: Compared with the concentrated liquid, the COD of the liquid phase product is reduced by 75%, the ammonia nitrogen is reduced by 60%, the total phosphorus is reduced by 68%, the total nitrogen is reduced by 50%, and the turbidity is reduced by 51%.

3. The water coal slurry gasification based leachate disposal method according to claim 1 or 2, characterized by: Compared with the concentrated liquid, the COD of the liquid phase product is reduced by 80%, the ammonia nitrogen is reduced by 64%, the total phosphorus is reduced by 98%, the total nitrogen is reduced by 55%, and the turbidity is reduced by 61%.

4. The method for disposing of landfill leachate by coal water slurry gasification according to claim 1, characterized by: In the garbage leachate pretreatment, the garbage leachate is concentrated 10 times by a permeation-reverse osmosis membrane.

5. The method for disposing of landfill leachate by coal water slurry gasification according to claim 1, wherein: In the preparation of the mixed coal powder, the grinding is carried out to 100 mesh and 200 mesh respectively and then mixed.

6. The method for disposing of landfill leachate by coal water slurry gasification according to claim 1, wherein: The fuel heat value of the composite coal water slurry is ≥20 MJ / kg.

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