A microorganism-plant combined mineralized garbage remediation method and system

Abstract

The present invention belongs to the field of waste treatment, and specifically discloses a method and system for repairing mineralized waste by combining microorganisms and plants, which includes the following steps: S1 excavates and screens a landfill to obtain mineralized waste contaminated by heavy metals, and places the mineralized waste in an infiltration device; S2 sequentially injects Bacillus pasteurii bacterial solution and reaction solution into the infiltration device; S3 repeats S2 several times to allow Bacillus pasteurii to fully repair the heavy metals in the mineralized waste; S4 takes out the mineralized waste and transfers it to a closed greening land, plants are planted in the closed greening land, and the plants are removed after a certain period of time to complete the repair of the mineralized waste. The present invention combines microbial repair technology and plant repair technology to repair and treat heavy metals in mineralized waste, and the equipment used is simple, easy to operate, effective, low cost, and realizes the resource utilization of mineralized waste.

Description

Technical Field

[0001] The present invention belongs to the field of garbage disposal, and more specifically, relates to a microorganism-plant combined mineralized garbage repair method and system. Background Art

[0002] my country's urban domestic waste is mainly treated by sanitary landfills. Landfills take a long time to fill and occupy a large area. With the continuous increase in waste production, the area of ​​landfills will continue to expand. The expansion of urban areas has also increased land use costs. Therefore, it is urgent to achieve sustainable sanitary landfills and resource utilization of waste.

[0003] Mineralized waste is the fine particles obtained by screening the urban domestic waste in the landfill after years of degradation and reaching a stable state. The content of nitrogen, phosphorus, organic matter, etc. in mineralized waste is higher than that in ordinary soil, and it has better physical properties and stronger adsorption capacity. Its good properties determine its multiple utilization methods. Studies have shown that mineralized waste can be used in landscaping, farmland, orchards, and the restoration and improvement of damaged soil. Using fine particles of mineralized waste to plant and cultivate plants such as Allium orchid and Cinnamomum camphora has additional economic benefits. Therefore, using mineralized waste as soil for greening is an important way to utilize it as a resource.

[0004] Sampling and analysis of different landfills showed that all landfills had excessive heavy metal content to varying degrees. As the landfill time increases, the degree of heavy metal pollution increases. Coupled with the current abuse of chemical agents and factory pollution, the problem of heavy metal pollution in the soil is becoming more and more serious. Therefore, in the process of realizing the resource utilization of mineralized waste, the heavy metals in it should be repaired to prevent heavy metals from causing secondary pollution to farmland and garden land.

[0005] The current methods used to repair heavy metals in mineralized waste mainly include chemical leaching and stabilization and solidification. Chemical leaching refers to the use of appropriate leaching solutions to clean contaminated mineralized waste in order to remove heavy metals. However, this technology has high requirements for soil texture and is not applicable in many places in my country. In addition, the leaching solution can cause secondary pollution. Stabilization and solidification repair methods use passivators such as lime, power plant ash, and iron-manganese oxides to reduce the migration of heavy metals. However, the heavy metals that are retained in the soil and passivated may still cause secondary pollution after several years. Therefore, there is an urgent need to find a heavy metal repair method with good treatment effect, simple operation, and little disturbance to mineralized waste. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a microorganism-plant combined mineralized garbage remediation method and system, the purpose of which is to combine microbial remediation technology and plant remediation technology to remediate heavy metals in mineralized garbage. The equipment used is simple, easy to operate, effective, low-cost, and realizes the resource utilization of mineralized garbage.

[0007] To achieve the above object, according to one aspect of the present invention, a microorganism-plant combined mineralized garbage remediation method is proposed, comprising the following steps:

[0008] S1 excavates and screens the landfill to obtain mineralized waste contaminated by heavy metals, and places the mineralized waste in an infiltration irrigation device;

[0009] S2 injects the Bacillus subtilis solution and the reaction solution into the infiltration irrigation device in sequence;

[0010] S3 repeats S2 several times to allow Bacillus pasteurianus to fully repair the heavy metals in the mineralized garbage;

[0011] S4 takes out the mineralized waste and transfers it to a closed green land, plants are planted in the closed green land, and the plants are removed after a certain period of time to complete the restoration of the mineralized waste.

[0012] As a further preferred embodiment, in S1, the mineralized waste is placed in the infiltration irrigation device by natural stacking, and is appropriately leveled when the mineralized waste approaches the top of the inner ring of the infiltration irrigation device.

[0013] As a further preferred method, after completing the remediation of the mineralized waste, soil samples to be tested are taken from the closed green space through the S-shaped point distribution method, and the heavy metals in the soil samples are extracted and detected using the toxic leaching method. The samples are compared with the limit values ​​in the specifications to evaluate the heavy metal pollution.

[0014] As a further preferred embodiment, in S2 and S3, OD 600 The concentration of the culture medium is 1.0 of Bacillus subtilis solution.

[0015] As further preferred, the reaction solution is a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride.

[0016] As a further preferred embodiment, in S2, the Bacillus subtilis liquid is first injected into the infiltration device through the pressure-applying device 1, and the injection is stopped after the air in the infiltration device is exhausted. After standing for 30 minutes, the leachate is discharged under a natural state; then the reaction liquid is injected into the infiltration device through the pressure-applying device 2, and the injection is stopped after the air in the infiltration device is exhausted. After standing for 8 hours, the leachate is discharged under a pressurized state.

[0017] As a further preferred embodiment, in said S4, the plants to be planted are selected according to the types of heavy metals in the mineralized waste, wherein Vetiveria zizanioides and Sedum foetida are selected for zinc and cadmium polluted mineralized waste, Lycopodiella cuneata is selected for chromium polluted mineralized waste, and Tall Fescue and White Clover are selected for copper polluted mineralized waste.

[0018] According to another aspect of the present invention, a microorganism-plant combined mineralized garbage remediation system for implementing the above method is provided, comprising a garbage storage unit, a garbage screening unit, a pressurized infiltration irrigation unit, and a plant remediation unit, wherein:

[0019] The garbage screening unit is used to screen the garbage dug out from the garbage storage unit to obtain mineralized garbage contaminated by heavy metals;

[0020] The pressurized infiltration unit is used for microbial remediation of mineralized garbage, and comprises an infiltration device, a pressurizing device 1, a pressurizing device 2, and a leachate collection and treatment device, wherein the infiltration device comprises an infiltration device outer wall and an infiltration device inner ring installed inside the infiltration device, the upper part of the infiltration device inner ring is provided with two layers of permeable metal plates, and permeable stones are arranged between the two layers of permeable metal plates, and the lower part of the infiltration device inner ring is provided with filter cloth, permeable stones, and permeable metal plates in sequence from top to bottom; the pressurizing device 1 and the pressurizing device 2 are both connected to the infiltration device, and the leachate collection and treatment device is installed below the infiltration device;

[0021] The plant restoration unit is used for performing plant restoration on mineralized garbage, and comprises a closed greening land and plants planted in the closed greening land.

[0022] As a further preferred embodiment, the pressurizing device 1 includes a connected air pressure controller 1 and a high-pressure water storage tank 1, and the pressurizing device 2 includes a connected air pressure controller 2 and a high-pressure water storage tank 2, and the high-pressure water storage tank 1 and the high-pressure water storage tank 2 are both connected to the infiltration irrigation device.

[0023] As a further preferred embodiment, the range of the air pressure controller 1 and the air pressure controller 2 is 2Mpa and the accuracy is 0.15%; the working pressure of the high-pressure water storage tank 1 and the high-pressure water storage tank 2 is 2.5Mpa and the volume is 1m 3 The volume of the infiltration irrigation device is not less than 3m 3 .

[0024] In general, the above technical solution conceived by the present invention has the following technical advantages compared with the prior art:

[0025] 1. The method of the present invention adopts microbial-plant combined remediation technology to treat heavy metals in mineralized garbage. The microbial remediation technology utilizes microbial precipitation and adsorption to effectively reduce free heavy metals in the soil. Plants effectively reduce, purify and remove heavy metals in the soil through plant extraction, plant volatilization, plant stabilization, root filtration and other technologies, thereby reducing the mobility and bioavailability of heavy metals in the soil. Both technologies are environmentally friendly and have little modification to mineralized garbage and soil structure.

[0026] 2. Microbial remediation technology is highly efficient but has the problem of insufficient long-term effectiveness; phytoremediation technology can completely repair heavy metals but the treatment time is relatively long and may cause heavy metal migration to pollute the surrounding soil. The use of combined remediation technology can more thoroughly repair heavy metals in mineralized waste, and phytoremediation technology can solve the problem of resource utilization of mineralized waste, and the planted plants have certain economic value.

[0027] 3. Compared with the existing chemical leaching method and stabilization solidification remediation method, the present invention has low requirements on soil texture and can completely remediate heavy metals, thus not causing secondary pollution to mineralized waste. In addition, the method of the present invention has simple equipment and process, is easy to operate and has low cost.

[0028] 4. The present invention specifically designs the infiltration irrigation device to improve the precipitation and adsorption effects of microbial remediation of mineralized garbage; at the same time, during plant remediation, the plants to be planted are selected according to the types of heavy metals in the mineralized garbage to specifically remove heavy metals in the soil. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of a microorganism-plant-combined mineralized garbage remediation system according to an embodiment of the present invention;

[0030] Figure 2 This is a schematic diagram of the internal structure of the infiltration irrigation device according to an embodiment of the present invention;

[0031] Figure 3 This is a flow chart of the microbial-plant combined mineralized garbage remediation method according to an embodiment of the present invention.

[0032] In all the drawings, the same figure numbers are used to represent the same elements or structures, among which: 1-garbage storage unit; 2-garbage screening unit; 3-pressurized infiltration irrigation unit; 4-phytoremediation unit; 5-landfill; 6-screening machine; 7-infiltration irrigation device; 8a-air pressure controller one; 8b-air pressure controller two; 9a-high-pressure water storage tank one; 9b-high-pressure water storage tank two; 10-leachate collection and treatment device; 11-plants; 12-enclosed green space; 13-outer wall of infiltration irrigation device; 14-permeable stone; 15-inner ring of infiltration irrigation device; 16-filter cloth; 17-permeable metal plate. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0034] The embodiment of the present invention provides a microorganism-plant combined mineralized garbage remediation system, such as Figure 1 As shown, it includes a garbage storage unit 1, a garbage screening unit 2, a pressurized infiltration unit 3, and a plant restoration unit 4, wherein:

[0035] The waste storage unit 1 includes a landfill 5 for storing and degrading urban domestic waste;

[0036] The garbage screening unit 2 includes a screening machine 6 for screening the garbage dug out from the landfill 5 to obtain mineralized garbage contaminated by heavy metals;

[0037] The pressurized infiltration unit 3 is used for microbial remediation of mineralized waste, and comprises an infiltration device 7, a pressurizing device 1, a pressurizing device 2, and a leachate collection and treatment device 10, wherein Figure 2 As shown, the infiltration irrigation device 7 includes an infiltration irrigation device outer wall 13 and an infiltration irrigation device inner ring 15 installed inside the infiltration irrigation device, the upper part of the infiltration irrigation device inner ring 15 is provided with two layers of permeable metal plates 17, and a permeable stone 14 is provided between the two layers of permeable metal plates 17, and the lower part of the infiltration irrigation device inner ring 15 is provided with filter cloth 16, permeable stone 14, and permeable metal plate 17 in sequence from top to bottom; the pressurizing device 1 includes a connected air pressure controller 18a and a high-pressure water storage tank 19a, and the pressurizing device 2 includes a connected air pressure controller 28b and a high-pressure water storage tank 29b, and the high-pressure water storage tank 19a and the high-pressure water storage tank 29b are both connected to the infiltration irrigation device 7; the leachate collection and treatment device 10 is installed below the infiltration irrigation device 7, which is a simple sewage treatment tank;

[0038] The plant restoration unit 4 is used for performing plant restoration on mineralized waste, and includes a closed greening land 12 and plants 11 planted in the closed greening land 12 .

[0039] Preferably, the range of the air pressure controller 1 8a and the air pressure controller 2 8b is 2Mpa and the accuracy is 0.15%; the working pressure of the high-pressure water storage tank 1 9a and the high-pressure water storage tank 2 9b is 2.5Mpa and the volume is 1m 3 The volume of the infiltration device 7 is not less than 3m 3 .

[0040] When the above system is used to repair mineralized waste containing heavy metals, Figure 3 As shown, the following steps are included:

[0041] S1 excavates and screens the landfill to obtain mineralized waste contaminated by heavy metals, and places the mineralized waste in an infiltration irrigation device; specifically, the mineralized waste is placed in the infiltration irrigation device by natural stacking, and is appropriately leveled when the mineralized waste approaches the top of the inner ring of the infiltration irrigation device.

[0042] S2 injects Bacillus subtilis solution and reaction solution into the infiltration irrigation device in sequence; specifically, a high-pressure water storage tank containing OD 600 The bacillus pasteuris bacterial solution of 1.0 is contained in the high-pressure water storage tank 2, and a mixed solution of 1mol / L urea and 1mol / L calcium chloride is contained in the high-pressure water storage tank 2 as the reaction solution; the bacillus pasteuris bacterial solution in the high-pressure water storage tank 1 is first injected into the infiltration irrigation device through the air pressure controller 1, and the injection is stopped after the air in the infiltration irrigation device is exhausted, and the leachate is discharged under a natural state after standing for 30 minutes; the reaction solution in the high-pressure water storage tank 2 is injected into the infiltration irrigation device through the air pressure controller 2, and the injection is stopped after the air in the infiltration irrigation device is exhausted, and the leachate is discharged under a pressurized state after standing for 8 hours, and all the leachate is discharged from the infiltration irrigation device to the leachate collection and treatment device, and the sewage is treated according to the pollution situation.

[0043] S3 repeats S2 several times, preferably twice, so that Bacillus pasteurianus can fully repair the heavy metals in the mineralized garbage.

[0044] S4 takes out the mineralized waste and transfers it to a closed green land, plants are planted in the closed green land, and the plants are removed after a certain period of time to complete the restoration of the mineralized waste. Specifically, the plants to be planted are selected according to the types of heavy metals in the mineralized waste. For zinc and cadmium polluted mineralized waste, vetiver and Sedum ovata are used, for chromium polluted mineralized waste, Ligusticum ovata is used, and for copper polluted mineralized waste, tall fescue and white clover are used. The planting time is selected according to the specific plants. Vetiver is planted for 30 days, Sedum ovata is planted for 180 days, Ligusticum ovata is planted for 120 days, tall fescue is planted for 50 days, and white clover can be planted sustainably due to its ecological ornamental value.

[0045] Furthermore, after completing S3, 3 samples of mineralized waste in the upper, middle and lower parts of the infiltration irrigation device were taken as soil samples to be tested. The weight of each soil sample was 1 kg. The heavy metals in the soil samples were extracted and tested using the toxic leaching method and compared with the limit values ​​in the specifications to evaluate the heavy metal pollution.

[0046] Furthermore, after completing the remediation of mineralized waste by S4, soil samples to be tested are taken from the closed green land through the S-shaped distribution method, and the heavy metals in the soil samples are extracted and detected using the toxic leaching method. The heavy metal pollution is evaluated by comparing them with the limit values ​​in the specifications.

[0047] The following are specific embodiments:

[0048] The remediation of mineralized waste in a landfill that had been closed for 10 years included the following steps:

[0049] (1) The mineralized waste in the landfill is excavated using an empirical method, and the heavy metal-contaminated mineralized waste is obtained by screening using a screening machine.

[0050] (2) Cultivation of Bacillus pasteurianus: the mother culture solution was mixed with a nutrient solution (20 g / L yeast extract, 10 g / L ammonium chloride, 10 mg / L manganese sulfate monohydrate, 24 mg / L nickel chloride hexahydrate, and 1 mol / L sodium hydroxide solution to adjust the pH to 8.5) at a ratio of 1:100 and cultured at 30°C and 160 rpm for 24 h. The OD 600 is 1.0; prepare a mixed reaction solution of urea and calcium chloride with a concentration of 1 mol / L.

[0051] (3) The heavy metal-contaminated mineralized waste is placed in the infiltration irrigation device. The mineralized waste is placed in a natural pile and is appropriately leveled when the soil sample approaches the top of the inner ring of the pressurized infiltration irrigation device.

[0052] (4) Add Bacillus pasteurianus liquid and reaction liquid into high-pressure water storage tank 1 9a and high-pressure water storage tank 2 9b respectively.

[0053] (5) Close the drainage valve of the infiltration device 7, open the water inlet valve, exhaust valve and valve of the high-pressure water storage tank 9a of the infiltration device 7, adjust the pressure controller 8a to 1 MPa, continue to inject the bacterial solution, and stop injecting liquid after the air in the infiltration device is completely exhausted. After standing for 30 minutes, open the drainage valve of the infiltration device 7 to discharge the leachate in a natural state.

[0054] (6) Close the drainage valve of the infiltration device 7, open the valve of the high-pressure water storage tank 2 9b, adjust the pressure controller 2 8b to 1Mpa, continue to inject the reaction liquid, and stop injecting liquid after the air in the infiltration device is completely exhausted. After standing for 8 hours, open the drainage valve of the infiltration device 7 to discharge the leachate under pressure.

[0055] (7) Repeat steps (5) and (6) twice.

[0056] (8) The mineralized waste was removed and three soil samples (1 kg each) were taken from the upper, middle and lower parts of the infiltration device. The heavy metal concentrations in the soil samples were tested by the toxic leaching method. After comparison with the specifications, it was found that the concentrations of heavy metals such as zinc, cadmium and chromium in the mineralized waste were lower than the specified limit values, while the concentration of heavy metal copper was higher than the specified limit values.

[0057] (9) The mineralized waste after primary treatment was transferred to a closed green space, and the tall fescue was planted for 50 days before the plants were removed. The soil samples to be tested were taken by the S-shaped distribution method, and the heavy metal concentration in the soil samples was detected by the toxic leaching method. After comparison with the standard, it was found that the concentration of heavy metal copper in the mineralized waste was lower than the standard limit.

[0058] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A microorganism-plant combined mineralized garbage remediation method, characterized in that: Based on the mineralized garbage restoration system, the mineralized garbage restoration system comprises a garbage storage unit (1), a garbage screening unit (2), a pressurized infiltration unit (3), and a plant restoration unit (4), wherein: The garbage screening unit (2) is used to screen the garbage excavated from the garbage storage unit (1) to obtain mineralized garbage contaminated by heavy metals; The pressurized infiltration unit (3) is used for microbial remediation of mineralized garbage, and comprises an infiltration device (7), a pressurizing device 1, a pressurizing device 2, and a leachate collection and treatment device (10), wherein the infiltration device (7) comprises an infiltration device outer wall (13) and an infiltration device inner ring (15) installed inside the infiltration device, the upper part of the infiltration device inner ring (15) is provided with two layers of permeable metal plates, and permeable stones are arranged between the two layers of permeable metal plates, and the lower part of the infiltration device inner ring (15) is provided with filter cloth, permeable stones, and permeable metal plates in order from top to bottom; the pressurizing device 1 and the pressurizing device 2 are both connected to the infiltration device (7), and the leachate collection and treatment device (10) is installed below the infiltration device (7); The plant restoration unit (4) is used to perform plant restoration on mineralized waste, and comprises a closed greening land (12) and plants (11) planted in the closed greening land (12); Mineralized waste remediation based on the mineralized waste remediation system includes the following steps: S1 excavates and screens the landfill to obtain mineralized waste contaminated by heavy metals, and places the mineralized waste in an infiltration irrigation device; S2: injecting Bacillus pasteurianus liquid and reaction liquid into the infiltration irrigation device in sequence; specifically, first injecting Bacillus pasteurianus liquid into the infiltration irrigation device through the first pressure device, stopping the injection after the air in the infiltration irrigation device is exhausted, and discharging the leachate under natural conditions after standing for 30 minutes; then injecting the reaction liquid into the infiltration irrigation device through the second pressure device, stopping the injection after the air in the infiltration irrigation device is exhausted, and discharging the leachate under pressurized conditions after standing for 8 hours; use OD 600 The reaction liquid is a mixed solution of 1 mol / L urea and 1 mol / L calcium chloride; S3 repeats S2 several times to allow Bacillus pasteurianus to fully repair the heavy metals in the mineralized garbage; S4 takes out the mineralized waste and transfers it to a closed green land, plants are planted in the closed green land, and the plants are removed after a certain period of time to complete the restoration of the mineralized waste.

2. The microorganism-plant combined mineralized garbage remediation method according to claim 1, characterized in that: In S1, the mineralized garbage is placed in the infiltration irrigation device by natural stacking, and is appropriately leveled when the mineralized garbage approaches the top of the inner ring of the infiltration irrigation device.

3. The microorganism-plant combined mineralized garbage remediation method according to claim 1, characterized in that: After completing the remediation of mineralized waste, soil samples to be tested are taken from the closed green space through the S-shaped distribution method. The heavy metals in the soil samples are extracted and tested using the toxic leaching method, and compared with the limit values ​​in the specifications to evaluate the heavy metal pollution.

4. The microorganism-plant combined mineralized garbage remediation method according to any one of claims 1 to 3, characterized in that: In S4, the plants to be planted are selected according to the types of heavy metals in the mineralized waste, wherein Vetiver and Sedum austriatum are selected for zinc and cadmium polluted mineralized waste, Prunus armeniaca is selected for chromium polluted mineralized waste, and Tall Fescue and White Clover are selected for copper polluted mineralized waste.

5. The microorganism-plant combined mineralized garbage remediation method according to claim 1, characterized in that: The pressurizing device 1 comprises a connected air pressure controller 1 (8a) and a high-pressure water storage tank 1 (9a), and the pressurizing device 2 comprises a connected air pressure controller 2 (8b) and a high-pressure water storage tank 2 (9b), and both the high-pressure water storage tank 1 (9a) and the high-pressure water storage tank 2 (9b) are connected to the infiltration irrigation device (7).

6. The microorganism-plant combined mineralized garbage remediation method according to claim 5, characterized in that: The range of the air pressure controller 1 (8a) and the air pressure controller 2 (8b) is 2Mpa and the accuracy is 0.15%; the working pressure of the high-pressure water storage tank 1 (9a) and the high-pressure water storage tank 2 (9b) is 2.5Mpa and the volume is 1m 3 The volume of the infiltration device (7) is not less than 3m 3 .

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