Method for accelerating aerobic stabilization of refuse landfill

Abstract

The invention provides a method for accelerating aerobic stabilization of a refuse landfill, which belongs to the technical field of refuse landfill treatment, and comprises the following steps: arranging a leachate recharge well in a refuse layer, and arranging two water injection pipes at different positions in the leachate recharge well; covering the garbage layer with soil; and respectively refluxing percolate added with different microbial complex microbial inoculants into the water injection pipes with different adding positions. By adopting the acceleration method for treatment, the degradation time of organic matters in the garbage can be shortened, the stabilization of the garbage yard is accelerated, and the stable operation cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of landfill management, in particular to a method for accelerating aerobic stabilization of a landfill. Background Art

[0002] At present, there are a large number of informal landfills in my country. These informal landfills fail to meet the requirements of sanitary landfill technical specifications and standards, and fail to cover the landfills in a timely manner and properly dispose of pollutants such as leachate and landfill gas, causing serious environmental pollution. These pollutions manifest themselves in the pollution of surface water and groundwater, pollution of the atmosphere, encroachment on land resources, pollution of soil and farmland, and breeding of mosquitoes and flies that spread diseases.

[0003] Aerobic bioreactor technology for the treatment of informal landfills is a landfill treatment technology that has emerged in recent years. The basic principle is to regard the landfill as a large bioreactor and transform the anaerobic conditions in the landfill into an aerobic environment through forced ventilation, water injection, and leachate reinjection. The organic waste in the landfill is aerobically degraded under suitable conditions of oxygen content, temperature, and water content to generate stable organic matter, inorganic matter, CO2, water, etc., reducing pollution to the soil, air, and water, and accelerating the stabilization process of the landfill.

[0004] However, in practice, it has been found that the leachate from informal landfills contains high concentrations of ammonia nitrogen. Repeated reinjection of the leachate causes the ammonia nitrogen content in the leachate to continue to increase, resulting in an imbalance in the C / N ratio of the pile, which to a certain extent inhibits the biological process of aerobic fermentation and slows down the stabilization process of the pile. The indigenous microorganisms in the garbage are of a single species and lack specific functions, which will also lead to unstable aerobic treatment effects and extended treatment cycles for the entire landfill, thereby increasing the operating and management costs of the process. Summary of the invention

[0005] In view of the defects in the prior art, the present invention creatively proposes a method for accelerating the aerobic stabilization of landfills, which optimizes the selection and addition of microbial agents, the construction of leachate recharge wells, and the way of sealing and covering the landfill, so as to achieve a good aerobic stabilization effect on landfills, especially informal landfills with high-concentration ammonia nitrogen leachate. Specifically:

[0006] A method for accelerating aerobic stabilization of a landfill comprising:

[0007] Step S1, setting a leachate recharging well in the garbage layer;

[0008] Step S2, on the upper surface of the garbage layer outside the leachate recharging well, forming a lower layer of a water-conducting filler layer, an upper layer of a water-conducting filler layer, and a greening soil layer in sequence from bottom to top;

[0009] Step S3, extending the first water injection pipe and the second water injection pipe into the leachate reinjection well, the first water injection pipe extending into the upper layer of the water-conducting filler layer, and the second water injection pipe extending into the garbage layer; at least a portion of the first water injection pipe located at the upper layer of the water-conducting filler layer, and at least a portion of the second water injection pipe located at the garbage layer are flower pipes;

[0010] Step S4, filling gravel into the leachate recharge well to the upper surface of the upper layer of the water-conducting filler layer, and filling bentonite and red clay in sequence on the upper surface of the gravel to the leachate recharge wellhead;

[0011] Step S5, injecting the leachate containing the microbial composite agent A into the first water injection pipe, and injecting the leachate containing the microbial composite agent B into the second water injection pipe.

[0012] Optionally, in step S2, the upper layer of the water-conducting filler layer is composed of a mixture of coal slag, ceramsite and coarse sand in a mass ratio of 2:1:1; the lower layer of the water-conducting filler layer is a covering material made of bentonite, a slow-release carbon source, gravel and an organic polymer, with a thickness of 5 cm. Specifically, when preparing the covering material, the organic polymer is formed into a liquid (such as dissolved in water), and then the gravel is wetted with the liquid organic polymer, and then bentonite and a slow-release carbon source are added in sequence, and the covering material is formed by mixing; the diameter of the gravel is 6-10 mm, the mass ratio of bentonite, slow-release carbon source, gravel and organic polymer is 30%: 3%: 65%: 2%, the organic polymer is selected from polyacrylamide, and the slow-release carbon source is selected from rice husks or sawdust.

[0013] Optionally, in step S2, nitrogen-fixing plants, such as ryegrass and legumes, are planted on the greening soil layer, and preferably the upper surface of the greening soil layer is kept flush with the leachate recharge wellhead.

[0014] Optionally, in step S3, the flower tube parts of the first water injection pipe and the second water injection pipe are hole-shaped openings or slit-shaped openings; the diameter of the hole-shaped openings is not greater than 6 mm, and the slit width of the slit-shaped openings is not greater than 1 mm; the opening surface area of ​​the flower tube is between 25% and 30% of the flower tube area, and the flower tube is wrapped with geotextile.

[0015] Optionally, in step S3, the thickness of the upper layer of the water-conducting filler layer is 50 cm, the length of the flower tube portion of the first water injection pipe is 40 cm; the length of the flower tube of the second water injection pipe is set according to the thickness of the garbage layer.

[0016] Optionally, in step S5, the microbial composite agent A is composed of solid bacterial powders of Pseudomonas stutzeri, Pichia pastoris, Bacillus subtilis, and Halomonas;

[0017] Pseudomonas stutzeri, with the deposit number CGMCC1.15316;

[0018] Pichia pastoris, with the accession number CGMCC2.2179;

[0019] Bacillus subtilis, deposit number CGMCC1.7740;

[0020] Halomonas, with the deposit number of CGMCCNO.9941;

[0021] The preparation method of the composite bacterial agent A is as follows: four bacterial agents are cultured separately and then mixed in a mass ratio of 30% of Pseudomonas stutzeri, 10% of Pichia pastoris, 20% of Bacillus subtilis, and 40% of Halomonas to prepare a dry bacterial agent.

[0022] Optionally, in step S5, the microbial composite agent B is composed of solid bacterial powders of Bacillus subtilis, Pichia pastoris, lactic acid bacteria, Phanerochaete chrysosporium, and Thiobacillus ferrooxidans;

[0023] Bacillus subtilis, deposit number CGMCC1.7740;

[0024] Pichia pastoris, with the accession number CGMCC2.2179;

[0025] Phanerochaete chrysosporium, with the accession number CGMCC3.7212;

[0026] Lactic acid bacteria, the deposit number is CGMCC No .5959;

[0027] Thiobacillus ferrooxidans, deposit number CGMCC NO.0727;

[0028] The preparation method of composite bacterial agent B is as follows: after culturing five bacterial agents separately, they are mixed in a mass ratio of 25% of Bacillus subtilis, 15% of Pichia pastoris, 45% of lactic acid bacteria, 10% of Phanerochaete chrysosporium, and 5% of Thiobacillus ferrooxidans to prepare a dry bacterial agent.

[0029] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0030] The present invention can simultaneously utilize plant absorption, filler adsorption and microbial action to efficiently remove ammonia nitrogen in leachate and garbage; the filler involved in the present invention has various types, can make full use of solid waste in the industrial field, is environmentally friendly, low-cost and stable in nature; the present invention selectively adds different microbial composite bacterial agents in layers according to the types of aerobic treatment pollutants in the landfill, utilizes the strengthening effect of exogenous functional microorganisms to improve the degradation efficiency of pollutants, strengthens the removal of leachate pollutants, reduces the difficulty of subsequent water treatment, shortens the repair cycle and reduces the treatment cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0032] Figure 1 It is a cross-sectional view of the use of the leachate recharge well of the present invention;

[0033] Among them: 1-the first water injection pipe, 2-the second water injection pipe, 3-red clay, 4-leachate recharge well, 5-green soil layer, 6-upper layer of water-conducting filler layer, 7-lower layer of water-conducting filler layer, 8-garbage layer, 9-geotextile, 10-flower pipe, 11-gravel, 12-bentonite. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is described below.

[0035] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0036] In the embodiments of the present invention, sometimes a subscript such as W1 may be mistakenly written as a non-subscript such as W1. When the difference is not emphasized, the meanings to be expressed are consistent.

[0037] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0038] The method for optimizing and accelerating aerobic stabilization of informal garbage landfills of the present invention comprises: selection and addition of microbial agents, construction of leachate recharging wells and methods of sealing and covering the landfills.

[0039] Two φ50mm water injection pipes are arranged in the φ200mm leachate reinjection well 4, namely the first water injection pipe 1 and the second water injection pipe 2. The first water injection pipe 1 is used for reinjecting the leachate with the addition of microbial composite agent A, and the second water injection pipe 2 is used for reinjecting the leachate with the addition of microbial composite agent B.

[0040] The part where the first water injection pipe 1 enters the upper layer 6 of the water-conducting filler layer is a flower pipe. The depth of the water injection pipe 1 is determined by the green soil layer and the upper layer of the water-conducting filler layer. The bottom of the pipe is located 10 cm above the bottom of the upper layer of the water-conducting filler layer. The part where the second water injection pipe 2 enters the garbage layer 8 is a flower pipe 10. The length is adjusted according to the actual thickness of the garbage layer. The flower pipe 10 is a hole-shaped opening with a hole diameter of no more than 6 mm and an opening surface area between 25% and 30%. It needs to be wrapped with 150g / m 2 Geotextile 9. Flower pipe 10 can also be replaced by slit pipe, and the slit width is not more than 1mm. Gravel 11 with a particle size of 1-2mm is filled between the first water injection pipe 1, the second main water pipe 2 and the wall of the leachate recharge well 4. The gravel 11 is backfilled to the top of the upper layer 6 of the water-conducting filler. Bentonite with a thickness of 10cm is backfilled on the gravel 11, and then red clay 3 is further backfilled to the top of the water injection well, which is on the same plane as the surrounding greening soil layer.

[0041] The greening soil layer 5 is a layer of soil with a thickness of 20-30 cm. Nitrogen-fixing plants, such as ryegrass, are preferably planted on the greening soil layer 5 .

[0042] The water-conducting filler layer is composed of an upper water-conducting filler layer 6 and a lower water-conducting filler layer 7. The upper water-conducting filler layer 6 and the lower water-conducting filler layer 7 are respectively mixed by different materials. The upper water-conducting filler layer 6 is composed of coal slag, ceramsite and coarse sand with a mass ratio of 2:1:1 and a diameter of 2-4 mm, and a thickness of 50 cm. The lower water-conducting filler layer 7 is a covering material prefabricated and synthesized by bentonite, slow-release carbon source, gravel and organic polymer, and has a thickness of 5 cm.

[0043] The working process of the method for accelerating aerobic stabilization of informal landfills of the present invention is:

[0044] The moisture content in the garbage pile is the basic condition and the most important factor to ensure aerobic operation. According to the needs of aerobic remediation reaction in the landfill, water (leachate or additional water) needs to be injected into the garbage to ensure good conditions for aerobic reaction. According to the monitoring of the humidity of the landfill garbage, the leachate reinjection system will automatically control the start of the reinjection pump, and the leachate added with the microbial composite agent A will enter the upper layer 6 of the water-conducting filler layer through the first water injection pipe 1 at a certain speed and flow rate. In the process of the leachate seeping to the surroundings, part of the ammonia nitrogen, organic matter and inorganic matter in the leachate will be adsorbed on the surface of the filler, part of the ammonia nitrogen, sulfate and other inorganic matter will be absorbed and utilized by the plant roots, and part of it will be degraded and converted by the microbial action of the added composite agent. The microbial composite agent A is mainly used to remove ammonia nitrogen and nitrate nitrogen in the leachate. The ammonia nitrogen adsorbed on the surface of the filler will be converted into nitrate under the action of microorganisms and will be separated from the surface, so that the adsorbed filler is regenerated. The lower layer 7 of the water-conducting filler layer can form a uniform, sticky, non-penetrating high-quality elastic layer after being hydrolyzed and expanded in water, providing a nutrient base for microorganisms. The added slow-release carbon source is continuously and slowly released outward, so that the filler can effectively act on the pollutant removal of the leachate for a long time, prevent the pollutants and gas in the garbage layer from escaping upward, and facilitate the collection of waste gas by the garbage dump exhaust system. At the same time, the leachate to which the microbial composite bacterial agent B is added is reinjected into the garbage layer 8 through the second water injection pipe 2. The garbage piles in informal landfills are all under anaerobic conditions for a long time, and contain a large amount of H2S and difficult-to-degrade organic matter. The present invention enriches the functional bacteria in the garbage pile, strengthens the biological action, and thus improves the garbage degradation efficiency. In addition to being able to decompose organic matter, the composite bacterial agent B of the present invention can also consume H2S and remove odor.

[0045] Example 1

[0046] The average concentration of ammonia nitrogen pollution in the groundwater extracted from a certain informal landfill site is 10mg / L, the average COD content of the leachate inside the landfill is 5620mg / L; the average ammonia nitrogen content is 392mg / L. According to the site survey results, the design depth of the injection well is 5-10m, with a total of 21 wells, and the well pipe diameter is 200mm. The well pipes entering the landfill garbage are all flower pipes. Two injection pipes are installed in the injection wells. The length of the flower pipe of the first injection pipe is 65cm, the micropore diameter is 1mm, and the opening surface area is 30% of the flower pipe area; the length of the flower pipe of the second injection pipe is determined according to the depth of the garbage, ranging from 4.15-9.15m, and the flower pipe specifications are the same as the first injection pipe. The upper layer of the water-conducting filler layer is composed of a mixture of coal slag, ceramsite and coarse sand with a mass ratio of 2:1:1 and a particle size of 2~4mm, with a thickness of 50cm; the lower layer of the water-conducting filler layer is a covering material made of bentonite, rice husk, gravel and polyacrylamide with a mass ratio of 30%:3%:65%:2%, with a thickness of 5cm. After placing two water injection pipes in the injection well, backfill gravel with a particle size of 2mm to the height of the upper top plate of the water-conducting filler layer, then backfill 10cm of bentonite on the gravel layer and then backfill red clay to the top of the injection well. The first water injection pipe injects a composite microbial agent mixed with a mass ratio of 30% of Pseudomonas stutzeri, 10% of Pichia pastoris, 20% of Bacillus subtilis and 40% of Halomonas. The dosage of the composite agent is 1:5000, that is, 200g of the agent is added for every cubic meter of leachate recharged. The long water injection pipe is injected with a composite bacterial agent prepared by mixing 25% Bacillus subtilis, 15% Pichia pastoris, 45% lactic acid bacteria, 10% Phanerochaete chrysosporium, and 5% ferrothiobacillus. The dosage of the composite bacterial agent is 1:10000, that is, 100g of bacterial agent is added for every 1 cubic meter of leachate recharged. The entire leachate recharge system is intermittently injected during operation, and is adjusted according to the data of the temperature and humidity monitoring system. The thickness of the covering soil layer is 0.3m, and ryegrass is planted on it. After 5 months of operation, the ryegrass planted in the covering soil layer has grown well, and the settlement of most settlement points is 5~37mm, and the settlement of some points has reached 159mm. Through the continuous extraction and recharge of garbage leachate, the fluctuation range of the moisture content of the garbage pile has been reduced from 27.49% to 51.05% to 37.25%~39.49%, and the moisture content of the pile is more evenly distributed, which is conducive to the aerobic reaction. The ammonia content in the groundwater at the monitoring point dropped to 0.44 mg / L, the ammonia nitrogen content in the leachate of the pile dropped to 34 mg / L, and the COD content dropped to 490 mg / L.

[0047] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for accelerating aerobic stabilization of a landfill, characterized in that: include: Step S1, setting a leachate recharging well in the garbage layer; Step S2, on the upper surface of the garbage layer outside the leachate recharging well, forming a lower layer of a water-conducting filler layer, an upper layer of a water-conducting filler layer, and a greening soil layer in sequence from bottom to top; Step S3, extending the first water injection pipe and the second water injection pipe into the leachate reinjection well, the first water injection pipe extending into the upper layer of the water-conducting filler layer, and the second water injection pipe extending into the garbage layer; at least a portion of the first water injection pipe located at the upper layer of the water-conducting filler layer, and at least a portion of the second water injection pipe located at the garbage layer are flower pipes; Step S4, filling gravel into the leachate recharge well to the upper surface of the upper layer of the water-conducting filler layer, and filling bentonite and red clay in sequence on the upper surface of the gravel to the leachate recharge wellhead; Step S5, injecting the leachate containing the microbial composite agent A into the first water injection pipe, and injecting the leachate containing the microbial composite agent B into the second water injection pipe.

2. The method according to claim 1, characterized in that: In step S2, the upper layer of the water-conducting filler layer is composed of a mixture of coal slag, ceramsite and coarse sand in a mass ratio of 2:1:1; the lower layer of the water-conducting filler layer is a covering material made of bentonite, slow-release carbon source, gravel and organic polymer, with a thickness of 5 cm.

3. The method according to claim 1, characterized in that In step S2, nitrogen-fixing plants, such as ryegrass and leguminous plants, are planted on the greening soil layer.

4. The method according to claim 1, characterized in that: In step S3, the flower tube parts of the first water injection pipe and the second water injection pipe are hole-shaped openings or slit-shaped openings; the diameter of the hole-shaped openings is not greater than 6 mm, and the slit width of the slit-shaped openings is not greater than 1 mm; the opening surface area of ​​the flower tube is between 25% and 30%, and the flower tube is wrapped with geotextile.

5. The method according to claim 1, characterized in that In step S3, the thickness of the upper layer of the water-conducting filler layer is 50 cm, the length of the flower tube part of the first water injection pipe is 40 cm; the length of the flower tube of the second water injection pipe is set according to the thickness of the garbage layer.

6. The method according to claim 1, characterized in that In step S5, the microbial composite agent A is composed of solid bacterial powders of Pseudomonas stutzeri, Pichia pastoris, Bacillus subtilis, and Halomonas; Pseudomonas stutzeri, with the deposit number CGMCC1.15316; Pichia pastoris, with the accession number CGMCC2.2179; Bacillus subtilis, deposit number CGMCC1.7740; Halomonas, with the deposit number of CGMCCNO.9941; The preparation method of the composite bacterial agent A is as follows: four bacterial agents are cultured separately and then mixed in a mass ratio of 30% of Pseudomonas stutzeri, 10% of Pichia pastoris, 20% of Bacillus subtilis, and 40% of Halomonas to prepare a dry bacterial agent.

7. The method according to claim 1, characterized in that In step S5, the microbial composite agent B is composed of solid bacterial powders of Bacillus subtilis, Pichia pastoris, lactic acid bacteria, Phanerochaete chrysosporium, and Thiobacillus ferrooxidans; Bacillus subtilis, deposit number CGMCC1.7740; Pichia pastoris, with the accession number CGMCC2.2179; Phanerochaete chrysosporium, with the accession number CGMCC3.7212; Lactic acid bacteria, the deposit number is CGMCC No .5959; Thiobacillus ferrooxidans, deposit number CGMCC NO.0727; The preparation method of the composite bacterial agent is as follows: after culturing five bacterial agents separately, the five bacterial agents are mixed in a mass ratio of 25% of Bacillus subtilis, 15% of Pichia pastoris, 45% of lactic acid bacteria, 10% of Phanerochaete chrysosporium, and 5% of Thiobacillus ferrooxidans to prepare a dry bacterial agent.

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