Manganese slag warehouse pollution control method based on in-situ microbial solidification / stabilization technology

Abstract

The invention discloses a manganese slag warehouse pollution control method based on an in-situ microorganism solidification / stabilization technology. The method comprises the following steps: preparing raw materials, obtaining microorganism mineralizing strains tolerant to manganese and ammonia nitrogen pollutants, and preparing microorganism solidification bacterium liquid and a carbon source for later use; injection and aeration: injecting the prepared microorganism solidified bacterium liquid and the carbon source into pore water of the manganese slag warehouse, and carrying out aeration treatment on the pore water; and induction reaction: carrying out induction reaction on the pore water of the manganese slag in a certain environment for a period of time until the leaching value of the pollutants meets a specified limit value, and completing the solidification of the manganese slag pollutants.

Description

Technical Field

[0001] The present invention relates to the technical field of manganese slag solidification, and particularly to a method for preventing and controlling pollution in a manganese slag yard based on in-situ microbial solidification / stabilization technology. Background Art

[0002] A large amount of manganese slag is generated during the mining and smelting of manganese ore. These manganese slags usually contain various heavy metals such as manganese, cadmium, lead, and other harmful substances such as ammonia nitrogen. With the continuous development of the manganese industry, the accumulation amount of manganese slag is also increasing continuously, posing a serious threat to the environment. Harmful substances such as heavy metals in manganese slag may enter the soil and water bodies through leaching, seepage, etc., causing soil pollution, water pollution, and ecological damage.

[0003] Traditional methods for preventing and controlling manganese slag pollution include physical methods and chemical methods, both of which belong to ex-situ prevention and control technologies. Physical methods such as landfill, covering, etc. only simply dispose of the manganese slag and cannot fundamentally solve the pollution problem in the manganese slag, and there is a risk of secondary pollution. Chemical methods such as chemical solidification, stabilization, etc. can reduce the mobility of heavy metals in manganese slag to a certain extent, but the use of chemical agents may cause new pollution to the environment, and the chemical method has a high cost, unstable effect, and requires long-term monitoring and maintenance.

[0004] Using microorganisms in nature for pollution prevention and control will not produce secondary pollution and is environmentally friendly. Microorganisms can grow and reproduce in the natural environment, have strong adaptability, and can play a role for a long time. Compared with traditional pollution prevention and control methods, the in-situ microbial solidification / stabilization technology does not require the additional addition of a large amount of chemical agents and has a lower cost. Microorganisms can solidify / stabilize heavy metals in manganese slag through adsorption, precipitation, redox, etc., and the effect is stable. Structures such as biofilms formed by microorganisms can enhance the stability of manganese slag and reduce the migration of heavy metals. Summary of the Invention

[0005] The purpose of the present invention is to propose a method for preventing and controlling pollution in a manganese slag yard based on in-situ microbial solidification / stabilization technology in view of the deficiencies of the prior art.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preventing and controlling pollution in a manganese slag yard based on in-situ microbial solidification / stabilization technology, the method comprising the following steps:

[0007] (1) Raw material preparation, obtaining microbial mineralization strains tolerant to manganese and ammonia nitrogen pollutants, and preparing microbial solidification bacterial liquid and carbon source for standby;

[0008] (2) Injection and aeration, injecting the prepared microbial solidification bacterial liquid and carbon source into the pore water of the manganese slag yard, and performing aeration treatment on the pore water;

[0009] (3) Inductive reaction: Conduct an inductive reaction on the pore water of the manganese slag until the pollutant leaching value meets the specified limit, and complete the solidification of the pollutants in the manganese slag.

[0010] Furthermore, the microbial solidifying bacterial solution is prepared from one or more of Nitrosomonas, Pseudomonas, Paracoccus, and Thauera.

[0011] Furthermore, the carbon source includes methanol, NaHCO3, and CH3COONa.

[0012] Furthermore, the aeration method is continuous aeration and intermittent aeration. The hour-by-hour aeration-stop ratio of intermittent aeration is 2 - 5:1, and the DO concentration is controlled between 0.5 - 1.5 mg / L.

[0013] Furthermore, the carbon source concentration is 2 - 5 g / L, and the injection method is one-time injection and batch injection. The number of batch injection times is 3 - 6 times.

[0014] Furthermore, a plurality of microbial grouting pipes are provided and are pressed into the ground by a drilling machine. The end of the grouting pipe is conical, and grouting small holes are provided on the side wall.

[0015] Furthermore, the grouting rate of the microbial solidifying bacterial solution is 0.5 - 5 L / min. The grouting time is set according to the pollutant concentration in the pore water of the manganese slag storage yard, which is 3 - 7 times, 2 - 8 h each time, and the OD600 of bacteria in the bacterial solution is between 1.0 - 6.0.

[0016] Furthermore, the manganese concentration in the pore water of the manganese slag storage yard is ≤1000 mg / L, and the ammonia nitrogen concentration is ≤1200 mg / L.

[0017] Furthermore, utilize the CO2 generated by microbial nitrification and denitrification to fix manganese ions, reduce the heavy metal migration ability. At the same time, carbonate minerals such as manganese carbonate seal the fissures in the karst area, further reducing the risk of pollution diffusion caused by pollutant seepage through groundwater.

[0018] Advantages of the present invention: Microbial solidification / stabilization is a natural process, which conforms to the concept of sustainable development. Microorganisms can continuously play a role in a suitable environment to maintain the long-term stability of manganese slag. This technology does not produce secondary pollution, does not introduce new harmful substances, and has little impact on the environment; it can adapt to different types and scales of manganese slag storage yards, has a certain adaptability to complex environmental conditions, especially has advantages for complex karst geology. Utilize the CO2 generated by microbial nitrification and denitrification to fix manganese ions, reduce the heavy metal migration ability. At the same time, carbonate minerals such as manganese carbonate seal the fissures in the karst area, further reducing the risk of pollution diffusion caused by pollutant seepage through groundwater. Description of the Drawings

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the change trend of pollutant concentration in the groundwater monitoring well downstream of the slag yard in Area B in the embodiment of the present invention;

[0021] Figure 2 It is a schematic diagram of the change trend of pollutant concentration in the groundwater monitoring well downstream of the slag yard in Area C in the embodiment of the present invention;

[0022] Figure 3 It is a schematic diagram of the change trend of pollutant concentration in the groundwater monitoring well downstream of the slag yard in Area A in the embodiment of the present invention;

[0023] Figure 4 It is a schematic diagram of the change trend of the permeability coefficient and particle porosity of the manganese slag yard. Detailed implementation manners

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described below in conjunction with the drawings and implementation examples. It should be understood that the specific implementation examples described here are only used to explain the present invention and are not used to limit the present invention.

[0025] In order to explore the prevention and control effect of the in-situ microbial solidification / stabilization technology, three areas with different depths of A (20m), B (25m), and C (30m) were selected in a manganese slag yard in the karst area of Guizhou, and the in-situ microbial solidification technology was used for treatment. The manganese concentration in the pore water of the manganese slag yard is ≤1000mg / L, and the ammonia nitrogen concentration is ≤1200mg / L.

[0026] In a sterile environment, one or more of Nitrosomonas, Pseudomonas, Paracoccus, and Thauera are added to the prepared Mn-containing 2+ and NH4 +In a high-concentration screening liquid medium, it was placed at 30°C and left standing for 48 h for tolerance screening culture. The components of the prepared high-concentration screening liquid medium were 2.75 g / L manganese sulfate, 3 g / L ammonium sulfate, and 4 g / L yeast extract powder. The pH was adjusted to 6.5 and sterilized at 121°C for 20 min. After the screening culture was completed, the strain obtained by the above acquisition method was taken for shake-flask scale-up culture. Then, 1% (mass fraction) of the cultured bacterial liquid was taken into a low-concentration liquid medium and shaken at 30°C and 100 rpm / min in a constant-temperature shaker for 24 h. The components of the low-concentration liquid medium were 0.7 g / L manganese sulfate, 0.75 g / L ammonium sulfate, and 2 g / L yeast extract powder, ensuring C / N = 4, adjusting the pH to 6.5, and sterilizing at 121°C for 20 min.

[0027] The grouting pipe was pressed into the ground by a drilling machine. The end of the grouting pipe was conical, and grouting holes were provided on the side wall. First, the carbon source was injected into the slag yard. The injection method in area A was divided into 3 injections, in area B was divided into 6 injections, and in area C was a one-time injection. The concentration was 2 - 5 g / L. The carbon source included methanol, NaHCO₃, or CH₃COONa. In the prepared screening microbial suspension, the bacterial OD600 was between 1.0 and 6.0. The grouting rate was 0.5 - 5 L / min. The grouting time was set according to the pollutant concentration in the pore water of the manganese slag yard, which was 3 - 7 times, 2 - 8 h each time. After the injection was completed, aeration started. The aeration methods were continuous aeration and intermittent aeration. The aeration-stop ratio of intermittent aeration was 2 - 5:1, and the DO concentration could be controlled between 0.5 and 1.5 mg / L. After the microbial induced reaction started, the groundwater monitoring wells downstream of the slag yard were continuously monitored, and the results were as follows Figures 1 - 3 shown.

[0028] From Figure 1 it can be seen that with the progress of the microbial solidification / stabilization treatment in area A, the concentrations of ammonia nitrogen and manganese ions in the groundwater continued to decline. The manganese concentration decreased from 70 mg / L to below 20 mg / L, and the ammonia nitrogen concentration decreased from 500 mg / L to below 200 mg / L.

[0029] From Figure 2 it can be seen that with the progress of the microbial solidification / stabilization treatment in area B, the concentrations of ammonia nitrogen and manganese ions in the groundwater continued to decline. The manganese concentration decreased from 10 mg / L to below 5 mg / L, and the ammonia nitrogen concentration decreased from 200 mg / L to about 100 mg / L.

[0030] From Figure 3 it can be seen that with the progress of the microbial solidification / stabilization treatment in area C, the concentrations of ammonia nitrogen and manganese ions in the groundwater continued to decline. The manganese concentration decreased from 5 mg / L to 0.05 mg / L, and the ammonia nitrogen concentration decreased from about 100 mg / L to below the detection limit.

[0031] During the process of microbial-induced reaction, as the porosity decreases, the permeability coefficient of manganese slag continuously decreases. As Figure 4 shown, it decreases from 10 -6 cm / s to the order of magnitude of 10 -7 cm / s. It can be seen from the results that the CO2 generated by microbial nitrification and denitrification can fix manganese ions, effectively reducing the heavy metal migration ability. At the same time, the newly mineralized products reduce the permeability coefficient of the slag yard, which can block the fissures in the karst area and further reduce the risk of pollution diffusion caused by groundwater leakage of pollutants.

[0032] The above embodiments are used to explain the present invention, rather than to limit the present invention. Any modification and change made to the present invention within the spirit and scope of the claims of the present invention fall within the protection scope of the present invention.

Claims

1. A method for preventing and controlling the pollution of manganese slag yard based on in-situ microbial solidification / stabilization technology, characterized in that: The method comprises the following steps: (1) Raw material preparation: obtaining microbial mineralization strains resistant to manganese and ammonia nitrogen pollutants, and preparing microbial solidified bacterial liquid and carbon source for standby; (2) Injection and aeration: injecting the prepared microbial solidified bacterial liquid and carbon source into the pore water of the manganese slag yard, and performing aeration treatment on the pore water; (3) Inductive reaction: performing an inductive reaction on the pore water of the manganese slag until the pollutant leaching value meets the specified limit, and completing the solidification of the manganese slag pollutants.

2. The pollution prevention and control method for manganese slag yard based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: The microbial solidified bacterial liquid is prepared from one or more of Nitrosomonas, Pseudomonas, Paracoccus, and Thauerella.

3. The pollution prevention and control method for manganese slag yard based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: The carbon source includes methanol, NaHCO3, and CH3COONa.

4. The pollution prevention and control method for manganese slag yard based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: The aeration method is continuous aeration and intermittent aeration. The hour-by-hour aeration-stop ratio of intermittent aeration is 2 - 5:1, and the DO concentration is controlled between 0.5 - 1.5 mg / L.

5. A method for preventing and controlling manganese slag yard pollution based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: The carbon source concentration is 2 - 5 g / L, and the injection method is single injection and batch injection. The number of batch injections is 3 - 6 times.

6. A method for preventing and controlling manganese slag yard pollution based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: A plurality of microbial grouting pipes are provided and are pressed into the ground by a drilling machine. The end of the grouting pipe is conical, and grouting small holes are provided on the side wall.

7. A method for preventing and controlling manganese slag yard pollution based on in-situ microbial solidification / stabilization technology as described in claim 1, characterized in that: The grouting rate of the microbial solidified bacterial liquid is 0.5 - 5 L / min. The grouting time is set according to the pollutant concentration in the pore water of the manganese slag yard, and is 3 - 7 times, 2 - 8 h each time. The OD600 of bacteria in the bacterial liquid is between 1.0 - 6.

0.

8. The pollution prevention and control method for manganese slag yard based on in-situ microbial solidification / stabilization technology according to claim 1, characterized in that: The manganese concentration in the pore water of the manganese slag yard is ≤1000 mg / L, and the ammonia nitrogen concentration is ≤1200 mg / L.

9. The pollution prevention and control method for manganese slag yard based on in-situ microbial solidification / stabilization technology as claimed in claim 1, wherein: Utilize the CO2 generated by microbial nitrification and denitrification to fix manganese ions, reduce the heavy metal migration ability. At the same time, carbonate minerals such as manganese carbonate in the mineralization products seal the fissures in the karst area, further reducing the pollution diffusion risk caused by the leakage of pollutants through groundwater.

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