Method for removing SMX in in-situ groundwater soil through TMAC / PAA coupling microbial flora

Abstract

The invention relates to the technical field of groundwater pollution treatment, and discloses a method for removing SMX in in-situ groundwater soil through TMAC / PAA coupled microbial flora. According to the method provided by the invention, materials for preparing the activated carbon TMAC are easy to obtain, synthesis conditions are simple, the method is environment-friendly, secondary pollution is not caused, the preparation cost is low, and batch production is easy. (2) the method provided by the invention shows excellent anti-interference capability and certain decontamination performance, improves the in-situ soil environment on the premise of low disturbance, provides a high-quality carbon source for microbial development, has good groundwater organic matter pollutant remediation potential and environmental safety, and is suitable for in-situ removal of SMX in soil groundwater. And (3) according to the method provided by the invention, real groundwater environment soil is utilized to simulate the removal process of SMX in a groundwater environment porous medium, and meanwhile, environmental compatibility is comprehensively considered, so that a new insight is provided for removing pollutants by coupling the in-situ groundwater environment soil with microbial flora.

Description

Technical Field

[0001] The present invention relates to the technical field of groundwater pollution control, and in particular to a method for removing SMX in in-situ groundwater soil by coupling a TMAC / PAA microbial flora. Background Art

[0002] Groundwater pollution is one of the important issues in the current field of environmental protection, among which the removal of organic pollutants is particularly critical.

[0003] Sulfamethoxazole (SMX) is a typical active pharmaceutical compound that can easily enter the groundwater system directly or indirectly through human production activities. It is also difficult to degrade and has high persistence in water bodies. In recent years, advanced oxidation technology has attracted much attention and is considered to be an effective means of treating SMX, but traditional advanced oxidation technology still cannot effectively degrade SMX.

[0004] Peracetic acid (PAA), as a strong oxidant, has high selectivity for the removal of different organic matter, and has the advantages of easy activation, wide pH range, and less toxic byproducts. It has unique advantages and broad application prospects in the removal of new pollutants in groundwater. Carbonaceous materials have become PAA activators that have attracted extensive attention and research by researchers because of their high specific surface area, developed pore structure, wide source, low cost, good thermal stability, and low reaction conditions.

[0005] In addition, as a heterogeneous activator, carbon material activated PAA also has the advantages of easy recycling, low risk of secondary pollution, wide adaptability, and no need for energy input. Studies have shown that sulfamethoxazole is one of the few antibiotics that can be degraded by microorganisms, and microbial degradation is the most promising method for removing residual sulfamethoxazole. In situ bioremediation technology reduces engineering costs and reduces the chance of direct human contact with pollutants. It has little environmental disturbance and can be combined with other groundwater pollution remediation technologies to achieve efficient degradation of pollutants in the groundwater environment. Therefore, combined with the coupling effect of carbon material heterogeneous activation technology and microorganisms, PAA has significant advantages and good application prospects in the degradation of organic pollutants. Summary of the invention

[0006] The purpose of the present invention is: Based on the above technical problems, the present invention provides a method for removing SMX in in-situ groundwater soil by coupling TMAC / PAA microbial flora.

[0007] In order to achieve the above object, the first aspect of the present invention provides a method for removing SMX in in-situ groundwater soil by coupling TMAC / PAA with microbial flora, the method comprising:

[0008] The soil sample was placed on a magnetic constant temperature stirrer for stirring, and then PAA and thermally modified activated carbon TMAC were added and mixed evenly. Timing was started from the addition of thermally modified activated carbon TMAC. At 0, 2, 18, 24, and 48 hours, the samples in the conical flask were weighed, and methanol was added respectively. The obtained samples were recorded as sample I, sample II, sample III, sample IV, and sample V respectively.

[0009] The test is terminated, and the above sample I, sample II, sample III, sample IV, and sample V are placed on an oscillator for oscillation, and then placed in a centrifuge for centrifugal separation, and the supernatants are taken respectively, and extracted respectively, and the obtained supernatants are combined respectively and recorded as supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V respectively;

[0010] The supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V were filtered using nylon filters, and the filtrates were taken and placed in sample bottles and sealed for storage. After the experiment, the residual SMX concentration was immediately detected using a high performance liquid chromatograph.

[0011] Preferably, the parameter settings of the magnetic constant temperature stirrer satisfy: a constant temperature of 20 to 30° C., and a constant rotation speed of 200 to 500 rpm.

[0012] According to a preferred embodiment, the method for preparing the thermally modified activated carbon TMAC comprises the following steps:

[0013] S1: Add activated carbon to ultrapure water and wash repeatedly, place it in an electric constant temperature blast drying oven at 80-100°C and dry it for 8-12 hours, take it out, cool it to room temperature, grind it, wash it with ethanol and ultrapure water three times respectively, place it in a drying oven again, dry it at 60°C for 8 hours, take it out, grind it again through a 120-150 mesh sieve to obtain an intermediate.

[0014] S2: The intermediate is transferred to a vacuum tube furnace, and subjected to high-temperature pyrolysis modification at a temperature ≥ 600°C in a nitrogen atmosphere, and kept at this temperature for 1 to 5 hours, and naturally cooled with the furnace, washed and dried to obtain thermally modified activated carbon TMAC.

[0015] Preferably, the amount of the thermally modified activated carbon TMAC is 0 to 12 mg / kg.

[0016] More preferably, the concentration of PAA is 0-1 mg / kg.

[0017] Preferably, the parameters of the oscillator are set to meet the following conditions: temperature is 20-30° C., rotation speed is 200-500 rpm, and oscillation time is 40-100 min.

[0018] Preferably, the extraction uses methanol as the extractant.

[0019] Preferably, the pore size of the nylon filter is 0.22 μm.

[0020] The method provided by the present invention has at least the following beneficial effects:

[0021] (1) The materials for preparing activated carbon TMAC in the method provided by the present invention are easy to obtain, the synthesis conditions are simple, the environment is friendly and does not cause secondary pollution, the preparation cost is low, and it is easy to mass produce.

[0022] (2) The method provided by the present invention exhibits excellent anti-interference ability and certain decontamination performance, improves the in situ soil environment under the premise of low disturbance, provides a high-quality carbon source for microbial development, has good groundwater organic pollutant remediation potential and environmental safety, and is suitable for the in situ removal of SMX in soil and groundwater.

[0023] (3) The method provided by the present invention utilizes real groundwater environment soil to simulate the removal process of SMX in the porous medium of the groundwater environment, while comprehensively considering environmental compatibility, which will provide new insights into the removal of pollutants by in situ groundwater environment soil coupled microbial flora. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram showing the SMX removal effect of soil samples in Examples 1 to 5 of the present invention and Comparative Example 1;

[0025] Figure 2 It is a diagram showing the SMX removal effect of soil samples in Example 3, Example 6 to Example 8, and Comparative Example 1 of the present invention;

[0026] Figure 3 It is a diagram showing the SMX removal effect of soil samples in Examples 9 to 10 and Comparative Examples 2 to 5 of the present invention;

[0027] Figure 4 It is a graph showing the results of KEGG secondary functional pathway analysis of microorganisms in soil samples of Example 11 and Comparative Examples 6 to 7 of the present invention.

[0028] Description of Reference Numerals

[0029] Instructions attached Figures 1-2 The "control" group is the experimental data of comparative example 1. DETAILED DESCRIPTION

[0030] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0031] In the present invention, the thermally modified activated carbon TMAC has abundant defects and oxygen-containing functional groups, such as hydroxyl (-OH), carboxyl (-COOH), carbonyl (-C=O), etc., and exhibits excellent oxidant effectiveness. The thermally modified activated carbon TMAC can directly affect the number of active sites in the reaction system and the efficiency of activated PAA. The thermally modified activated carbon TMAC has stable and excellent activation performance in a complex soil environment, and the active oxides generated by activation are not easily affected by the soil environment.

[0032] In the present invention, in the porous medium, the thermally modified activated carbon TMAC and PAA show good enrichment effects. Since the thermally modified activated carbon TMAC can effectively activate PAA, electrons and RO·(CH3C(O)OO·, CH3C(O)O·) are transferred, thereby promoting the degradation of SMX.

[0033] In the present invention, TMAC / PAA induces the formation of microbial flora, exhibits a positive effect on the ecological balance and material circulation process of the site, enhances the metabolic intensity of soil microorganisms, and exhibits good coupling in degrading target pollutants.

[0034] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, the raw materials are all commercially available.

[0035] In the following examples, unless otherwise specified, soil sample I is soil contaminated with 10 mg / kg SMX sampled from an in-situ saturated aquifer of groundwater;

[0036] Soil sample II was sterilized contaminated soil sterilized at 121°C for 20 min.

[0037] Preparation Example

[0038] This example is used to provide a method for preparing thermally modified activated carbon TMAC, which comprises:

[0039] S1: Add ultrapure water to commercial activated carbon and wash it repeatedly, place it in an electric constant temperature blast drying oven at 80°C and dry it for 12 hours, take it out, cool it to room temperature, grind it, wash it with ethanol and ultrapure water three times respectively, place it in a drying oven again, dry it at 60°C for 8 hours, take it out, grind it again and pass it through a 120-mesh sieve to obtain an intermediate.

[0040] S2: The intermediate was transferred to a vacuum tube furnace, and subjected to high-temperature pyrolysis modification at 600°C in a nitrogen atmosphere, and kept at this temperature for 1 hour, and naturally cooled with the furnace, washed and dried to obtain thermally modified activated carbon TMAC.

[0041] Example 1

[0042] This example is used to provide a method for removing SMX in in-situ groundwater soil by coupling TMAC / PAA with microbial flora, the method comprising:

[0043] 350 g of soil sample I was placed in a conical flask, transferred to a magnetic thermostatic stirrer, stirred at a constant temperature of 25°C and a constant speed of 300 rpm, and then 0.25 mg / kg PAA and 0 mg / kg thermally modified activated carbon TMAC were added and mixed evenly. Timing was started from the addition of TMAC. At 0, 2, 18, 24, and 48 h, 15 g of the sample in the conical flask was weighed, and 10 mL of methanol was added to each of them. The obtained samples were recorded as sample I, sample II, sample III, sample IV, and sample V, respectively.

[0044] The test was terminated, and the above sample I, sample II, sample III, sample IV, and sample V were placed on an oscillator, respectively, and oscillated at a temperature of 25° C. and a speed of 300 rpm for 40 min, and then placed in a centrifuge, respectively, and centrifuged at a speed of 4000 rpm for 5 min, and the supernatants were taken respectively. In order to avoid experimental errors, methanol was used as an extractant, and they were fully extracted (supernatants were taken), and the obtained supernatants were combined respectively, and recorded as supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V;

[0045] The supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V were filtered using a nylon filter with a membrane pore size of 0.22 μm, and the filtrates were taken and placed in sample bottles and sealed for storage. After the experiment, the residual SMX concentration was immediately detected using a high performance liquid chromatograph.

[0046] Example 2

[0047] The method of Example 1 was followed, except that the amount of thermally modified activated carbon TMAC was 6 mg / kg, and the remaining steps and parameters were the same as those of Example 1.

[0048] Example 3

[0049] The method of Example 1 was followed, except that the amount of thermally modified activated carbon TMAC was 8 mg / kg, and the remaining steps and parameters were the same as those of Example 1.

[0050] Example 4

[0051] The method of Example 1 was followed, except that the amount of thermally modified activated carbon TMAC was 10 mg / kg, and the remaining steps and parameters were the same as those of Example 1.

[0052] Example 5

[0053] The method of Example 1 was followed, except that the amount of thermally modified activated carbon TMAC was 12 mg / kg, and the remaining steps and parameters were the same as those of Example 1.

[0054] Example 6

[0055] The method of Example 3 was followed, except that the concentration of PAA was 0 mg / kg, and the remaining steps and parameters were the same as those of Example 3.

[0056] Example 7

[0057] The method of Example 3 was followed, except that the concentration of PAA was 0.75 mg / kg, and the remaining steps and parameters were the same as those of Example 3.

[0058] Example 8

[0059] The method of Example 3 was followed, except that the concentration of PAA was 1 mg / kg, and the remaining steps and parameters were the same as those of Example 3.

[0060] Comparative Example 1

[0061] The method of Example 1 was followed, except that PAA was not added, and the remaining steps and parameters were the same as those of Example 1.

[0062] Example 9

[0063] The method of Example 3 was followed, except that the timing was started from the addition of TMAC, and 15 g of the sample in the conical flask was taken after 48 hours. The remaining steps and parameters were the same as those of Example 3.

[0064] Comparative Example 2

[0065] The method of Example 9 was followed, except that PAA and thermally modified activated carbon TMAC were not added, and the remaining steps and parameters were the same as those of Example 9.

[0066] Comparative Example 3

[0067] The method of Example 9 was followed, except that PAA was not added, and the remaining steps and parameters were the same as those of Example 9.

[0068] Example 10

[0069] The method of Example 9 was followed, except that the same amount of soil sample II was used to replace the soil sample I, and the remaining steps and parameters were the same as those of Example 9.

[0070] Comparative Example 4

[0071] The method of Example 10 was followed, except that PAA and thermally modified activated carbon TMAC were not added, and the remaining steps and parameters were the same as Example 10.

[0072] Comparative Example 5

[0073] The method of Example 10 was followed, except that PAA was not added, and the remaining steps and parameters were the same as Example 10.

[0074] Embodiment 11

[0075] The method of Example 9 was followed, except that 15 g of the sample in the conical flask was taken for sampling after 40 days of the test. The remaining steps and parameters were the same as those of Example 9.

[0076] Comparative Example 6

[0077] The method of Comparative Example 2 was followed, except that 15 g of the sample in the conical flask was taken for sampling after the test was carried out for 40 days, and the remaining steps and parameters were the same as those of Comparative Example 2.

[0078] Comparative Example 7

[0079] The method of Comparative Example 3 was followed, except that 15 g of the sample in the conical flask was taken for sampling after 40 days of the test, and the remaining steps and parameters were the same as those of Comparative Example 3.

[0080] Test Example 1

[0081] Summarizing the SMX removal rates of soil samples in Examples 1 to 5 and Comparative Example 1, the results are as follows: Figure 1 As shown, the horizontal axis is the reaction time and the vertical axis is the SMX removal rate.

[0082] Depend on Figure 1 It can be seen that under different thermally modified activated carbon TMAC dosages, the SMX removal rate in the TMAC / PAA system is significantly different. Specifically, with the increase in the amount of thermally modified activated carbon TMAC, the SMX removal rate increases, and it can be seen that the two are positively correlated. When thermally modified activated carbon TMAC is not added (Example 1), the SMX removal effect is greatly reduced, but the effect is not obvious compared with the control group.

[0083] Test Example 2

[0084] Summarizing the SMX removal rates of soil samples in the above-mentioned Examples 3, 6 to 8, and Comparative Example 1, the results are as follows: Figure 2 As shown, the horizontal axis is the reaction time and the vertical axis is the SMX removal rate.

[0085] Depend on Figure 2 It can be seen that PAA can significantly improve the removal rate of SMX by the TMAC / PAA system. As the concentration of PAA continues to increase, the removal rate of SMX increases accordingly, showing a good positive correlation. At the same time, when the concentration of PAA continues to increase, the contact between PAA and TMAC increases, and the activation sites of TMAC can be occupied faster, greatly improving the removal rate of SMX. When PAA is not added (Example 6), the SMX removal rate is greatly reduced relative to the control group.

[0086] Test Example 3

[0087] Summarizing the SMX removal rates of soil samples in Examples 9 to 10 and Comparative Examples 2 to 5, the results are as follows: Figure 3 As shown, the horizontal axis is the reaction time and the vertical axis is the SMX removal rate.

[0088] Depend on Figure 3 It can be seen that whether the soil sample has been sterilized is not only positively correlated with the SMX removal rate, but the differences within each experimental group also show a high degree of regularity. With the addition of thermally modified activated carbon TMAC and PAA, the difference in SMX removal rates between sterilized soil samples or non-sterilized soil samples is gradually increasing. When thermally modified activated carbon TMAC and PAA are added to the soil together, the environmental pressure from PAA promotes the improvement of the in situ microbial population in the soil, which can fully resist environmental stress and increase the number of microorganisms that use SMX as a carbon source. Therefore, in situ microorganisms have a certain synergistic effect on the degradation of SMX by TMAC / PAA.

[0089] Test Example 4

[0090] Summarizing the KEGG secondary functional pathway analysis of microorganisms in the soil samples of Example 11 and Comparative Examples 6 to 7, the results are as follows Figure 4 shown.

[0091] Depend on Figure 4 It can be seen that the microbial community after TMAC / PAA treatment is stronger and more active, with significant improvements in pathways related to amino acid metabolism, carbohydrate metabolism, energy production, as well as membrane transport, folding, sorting and degradation, cell communication and cell movement. Lysobacter is a key bacterial genus in TMAC / PAA-modified groundwater porous media, which promotes the activity of active microbial communities in the SMX degradation process by using organic pollutants as carbon sources and multiplying in large numbers, while also potentially dissolving other organisms through its hydrolytic enzymes.

[0092] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for removing SMX from in-situ groundwater and soil by coupling TMAC / PAA with microbial flora, characterized in that: The method includes: The soil sample was placed on a magnetic constant temperature stirrer for stirring, and then PAA and thermally modified activated carbon TMAC were added and mixed evenly. Timing was started from the addition of thermally modified activated carbon TMAC. At 0, 2, 18, 24, and 48 hours, the samples in the conical flask were weighed, and methanol was added respectively. The obtained samples were recorded as sample I, sample II, sample III, sample IV, and sample V respectively. The test is terminated, and the above sample I, sample II, sample III, sample IV, and sample V are placed on an oscillator for oscillation, and then placed in a centrifuge for centrifugal separation, and the supernatants are taken respectively, and extracted respectively, and the obtained supernatants are combined respectively and recorded as supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V respectively; The supernatant I, supernatant II, supernatant III, supernatant IV, and supernatant V were filtered using nylon filters, and the filtrates were taken and placed in sample bottles and sealed for storage. After the experiment, the residual SMX concentration was immediately detected using a high performance liquid chromatograph.

2. The method according to claim 1, wherein: The parameter settings of the magnetic constant temperature stirrer meet the following requirements: the constant temperature is 20-30° C., and the constant rotation speed is 200-500 rpm.

3. The method according to claim 1 or 2, wherein: The method for preparing the thermally modified activated carbon TMAC comprises the following steps: S1: Add activated carbon to ultrapure water and wash repeatedly, place it in an electric constant temperature blast drying oven at 80-100°C and dry it for 8-12 hours, take it out, cool it to room temperature, grind it, wash it with ethanol and ultrapure water three times respectively, place it in a drying oven again, dry it at 60°C for 8 hours, take it out, grind it again through a 120-150 mesh sieve to obtain an intermediate. S2: The intermediate is transferred to a vacuum tube furnace, and subjected to high-temperature pyrolysis modification at a temperature ≥ 600°C in a nitrogen atmosphere, and kept at this temperature for 1 to 5 hours, and naturally cooled with the furnace, washed and dried to obtain thermally modified activated carbon TMAC.

4. The method according to claim 1 or 2, wherein: The dosage of the thermally modified activated carbon TMAC is 0 to 12 mg / kg.

5. The method according to claim 1 or 2, wherein: The concentration of the PAA is 0-1 mg / kg.

6. The method according to claim 1 or 2, wherein: The parameters of the oscillator are set to meet the following conditions: temperature is 20-30° C., rotation speed is 200-500 rpm, and oscillation time is 40-100 min.

7. The method according to claim 1 or 2, wherein: The extraction uses methanol as the extraction agent.

8. The method according to claim 1 or 2, wherein: The membrane pore diameter of the nylon filter is 0.22 μm.

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