A method for remediating contaminated soil based on microbial augmentation

Abstract

The present application relates to the technical field of soil remediation, and particularly relates to a method for remediation of contaminated soil based on microbial reinforcement, comprising the following steps: S1, adding Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis and Pseudomonas aeruginosa into a culture solution and mixing uniformly to obtain a microbial agent; S2, soaking a carrier into the microbial agent and culturing at 30-35 DEG C for 1-3 days; and S3, spreading the carrier loaded with the microorganism into soil. The microbial agent can effectively adsorb and degrade heavy metal pollutants in the soil, reduce the content of heavy metal ions in the soil, and increase the aeration of the soil. Furthermore, the microbial agent is fixed by the carrier, which can reduce the loss of the microbial agent and ensure the remediation effect of the microbial agent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, in particular to a method for remediation of contaminated soil based on microbial reinforcement. BACKGROUND

[0002] Due to the influence of human activities, such as industrial emissions, pesticide use, waste disposal, etc., heavy metals are over-standard accumulated in the soil, so that the soil contains a large amount of lead, cadmium, arsenic, mercury and other heavy metals. Since these heavy metals are not biodegradable in the soil, they are easily enriched in the plant body and ultimately enter the human body, endangering human health.

[0003] At present, the methods for remediation of heavy metals in soil mainly include physical, chemical, biological and other methods. Among them, the physical and chemical methods for remediation of heavy metal contaminated soil are expensive, destroy the environment, are easy to cause secondary pollution, and often cannot achieve the purpose of truly removing heavy metals. The biological remediation technology is concerned by people because of its less secondary pollution, various treatment forms, relatively simple operation and less environmental disturbance. In the prior art, microbial remediation usually directly inoculates microorganisms into the soil. This method is not easy to fix the strain, and often causes the loss of microorganisms due to rain, so that the effect of microbial remediation is poor and the degree of soil pollution is difficult to improve. SUMMARY

[0004] In order to solve the above problems, the present application provides a method for remediation of contaminated soil based on microbial reinforcement.

[0005] The technical scheme of the present application is: a method for remediation of contaminated soil based on microbial reinforcement, comprising the following steps:

[0006] S1, Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis and Pseudomonas aeruginosa are added to the culture solution and mixed uniformly to obtain a microbial inoculant, and the mass ratio of Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, Pseudomonas aeruginosa and the culture solution is 5-7:3-6:2-3:2-4:80-100;

[0007] S2, the carrier is soaked in the microbial inoculant with 3-5 times of its own weight, and is cultured at 30-35 DEG C for 1-3 days. During the culture process, the microbial inoculant is put into a shaking table and shaken for 15-25 minutes every 5-8 hours. The initial temperature of the shaking table is 30-35 DEG C, and the temperature of the shaking table gradually decreases to 5-10 DEG C during the shaking process. After the culture is completed, the carrier is taken out to obtain a carrier loaded with microorganisms; the carrier is chitosan / aluminum titanate composite gel;

[0008] S3, the soil in the area to be repaired is excavated by 5-10 cm, the carrier loaded with microorganisms is sown into the soil, then the soil in the area to be repaired is backfilled, and water is sprayed into the area to be repaired.

[0009] Description: The microbial inoculant of the above method can effectively adsorb and degrade heavy metal pollutants in the soil, reduce the content of heavy metal ions in the soil, and increase the aeration of the soil. The microbial inoculant is fixed by the carrier, which can reduce the loss of the microbial inoculant and ensure the repair effect of the microbial inoculant.

[0010] Further, the culture medium ingredients include, by mass percentage: glucose 0.5-3%, peptone 5-10%, sodium chloride 1-3%, vitamin 0.2-0.6%, arginine 5-10%, beef extract 10-20%, magnesium sulfate 0.1-0.3%, agar 10-15%, and the rest is deionized water.

[0011] Description: The above culture medium can provide sufficient nutrients, provide necessary energy and raw materials for the proliferation of microorganisms, and ensure that the microbial inoculant can be fully loaded onto the carrier.

[0012] Further, the amplitude of the shaker is 20-30 mm, and the rotation speed is 100-150 rpm.

[0013] Description: Limiting the amplitude and rotation speed of the shaker can ensure uniform distribution of nutrients, so that the microbial inoculant is uniformly loaded on the carrier.

[0014] Further, the temperature reduction rate of the shaker during the oscillation process is 2-3℃ / min.

[0015] Description: By reducing the temperature, the pore size of the carrier can be reduced, and the loss of microorganisms can be reduced. Limiting the cooling rate can prevent the microorganisms from losing activity too quickly.

[0016] Further, the water spraying amount is 3-6 L per mu.

[0017] Description: Spraying water can ensure the water content of the land, improve the soil humidity, and ensure sufficient water for the growth and proliferation of microorganisms.

[0018] Further, the spreading amount of the microbial-loaded carrier is 200-300 g per mu.

[0019] Description: Limiting the spreading amount of the microbial-loaded carrier can reduce waste and ensure the repair effect of the microbial inoculant on the soil.

[0020] Further, the carrier is a chitosan / aluminum titanate composite gel, and the preparation method of the chitosan / aluminum titanate composite gel comprises the following steps:

[0021] Step 1: Dissolve aluminum nitrate in anhydrous ethanol and stir until the aluminum nitrate is completely dissolved to obtain mixed solution A; add chitosan to glacial acetic acid solution and stir until the chitosan is completely dissolved to obtain mixed solution B; the mass percentage of aluminum nitrate in mixed solution A is 2-4%, the mass percentage of chitosan in mixed solution B is 1-3%, and the mass ratio of mixed solution A to mixed solution B is 1:1-1.5;

[0022] Step 2: Divide the mixed solution B into 3 to 5 portions and add it to the mixed solution A. After each addition of mixed solution B, stir the mixed solution A for 5 to 10 minutes. During the stirring process, continuously add tetrabutyl titanate to the mixed solution A. After each stirring, use ammonia water to adjust the pH of the mixed solution A to neutral.

[0023] Step 3: After adding all of the mixed solution B, continue stirring the mixed solution A at 40-50℃ for 1-2 hours. After filtration and drying, chitosan / aluminum titanate composite gel is obtained.

[0024] Explanation: The above method generates aluminum titanate by reacting aluminum nitrate with tetrabutyl titanate. At the same time, tetrabutyl titanate can act as a crosslinking agent to form a composite gel between chitosan and aluminum titanate. The chitosan / aluminum titanate composite gel has many pores, which allow microorganisms to be evenly distributed within the pores. Furthermore, the volume of chitosan / aluminum titanate can expand with temperature changes to control the slow release of microorganisms. Chitosan / aluminum titanate also has an adsorption effect on heavy metal ions, enabling microorganisms to fully degrade heavy metal ions in the soil.

[0025] Furthermore, the mass concentration of the glacial acetic acid solution is 2-4%.

[0026] Note: Limiting the concentration of glacial acetic acid solution ensures the solubility of chitosan and prevents it from failing to dissolve completely.

[0027] Furthermore, the amount of tetrabutyl titanate added each time accounts for 30-40% of the mass of aluminum nitrate.

[0028] Note: Limiting the amount of tetrabutyl titanate added ensures that tetrabutyl titanate reacts fully with aluminum nitrate, thereby improving the conversion rate of aluminum titanate.

[0029] The beneficial effects of this invention are:

[0030] (1) The microbial agent of the present invention can effectively adsorb and degrade heavy metal pollutants in the soil, reduce the content of heavy metal ions in the soil, increase the aeration of the soil, and the microbial agent is fixed by a carrier, which can reduce the loss of microbial agent and ensure the remediation effect of microbial agent.

[0031] (2) In this invention, aluminum titanate is generated by reacting aluminum nitrate with tetrabutyl titanate. At the same time, tetrabutyl titanate can be used as a crosslinking agent to form a composite gel between chitosan and aluminum titanate. The chitosan / aluminum titanate composite gel has many pores, and microorganisms can be evenly distributed in the pores. The volume of chitosan / aluminum titanate can expand with temperature changes to control the slow release of microorganisms. Chitosan / aluminum titanate has an adsorption effect on heavy metal ions, which enables microorganisms to fully degrade heavy metal ions in the soil. Attached Figure Description

[0032] Figure 1 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 1 of this invention;

[0033] Figure 2 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 2 of this invention;

[0034] Figure 3 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 3 of this invention;

[0035] Figure 4 This is a line graph showing the reduction rate of heavy metal ion content in Experiment Example 4 of this invention;

[0036] Figure 5 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 5 of this invention;

[0037] Figure 6 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 6 of this invention;

[0038] Figure 7 This is a line graph showing the reduction rate of heavy metal ion content in Experimental Example 7 of this invention;

[0039] Figure 8 This is a line graph showing the rate of decrease in heavy metal ion content in Experimental Example 8 of this invention. Detailed Implementation

[0040] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0041] Example 1: A method for remediating contaminated soil based on microbial enhancement, comprising the following steps:

[0042] S1. Add Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, and Pseudomonas aeruginosa to the culture medium and mix evenly to obtain a microbial inoculum. The mass ratio of Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, Pseudomonas aeruginosa, and culture medium is 6:4.5:2.5:3:90. Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, and Pseudomonas aeruginosa were all purchased from the China Industrial Microbial Culture Collection Center, with accession numbers CICC 24713, CICC 23812, CICC 10098, and CICC 24649, respectively.

[0043] S2. The carrier was immersed in 4 times its own weight of microbial inoculant and incubated at 32℃ for 2 days. During the incubation, the microbial inoculant was placed in a shaker and shaken for 20 minutes every 6.5 hours. The initial temperature of the shaker was 32℃, and the temperature of the shaker was gradually reduced to 7℃ during the shaking process. After the incubation was completed, the carrier was removed to obtain the microbial-loaded carrier. The carrier was a chitosan / aluminum titanate composite gel. The amplitude of the shaker was 25 mm, the rotation speed was 120 rpm, and the temperature of the shaker decreased at a rate of 2.5℃ / min during the shaking process.

[0044] S3. Remove 8cm of soil from the area to be repaired, spread the microbial carrier into the soil, then backfill the soil in the area to be repaired, and sprinkle water on the area; the amount of water sprinkled is 4L per acre; the amount of microbial carrier spread is 250g per acre.

[0045] The culture medium comprises, by mass percentage: 1.5% glucose, 8% peptone, 2% sodium chloride, 0.4% vitamins, 8% arginine, 15% beef extract, 0.2% magnesium sulfate, 12% agar, and the remainder being deionized water.

[0046] The preparation method of chitosan / aluminum titanate composite gel includes the following steps:

[0047] Step 1: Dissolve aluminum nitrate in anhydrous ethanol and stir until the aluminum nitrate is completely dissolved to obtain mixed solution A; add chitosan to a 3% (w / w) glacial acetic acid solution and stir until the chitosan is completely dissolved to obtain mixed solution B; the mass percentage of aluminum nitrate in mixed solution A is 3%, the mass percentage of chitosan in mixed solution B is 2%, and the mass ratio of mixed solution A to mixed solution B is 1:1.25;

[0048] Step 2: Divide solution B into 4 equal portions and add it to solution A. After each addition of solution B, stir solution A for 8 minutes. During the stirring process, continuously add tetrabutyl titanate to solution A. After each stirring, adjust the pH of solution A to neutral using ammonia. The amount of tetrabutyl titanate added each time is 35% of the mass of aluminum nitrate, and the mass concentration of ammonia is 15%.

[0049] Step 3: After adding all of the mixed solution B, continue stirring the mixed solution A at 45°C for 1.5 hours. After filtration and drying, chitosan / aluminum titanate composite gel is obtained.

[0050] Example 2: This example is basically the same as Example 1, except that the mass ratio of Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, Pseudomonas aeruginosa and culture medium is 5:3:2:2:80.

[0051] Example 3: This example is basically the same as Example 1, except that the mass ratio of Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, Pseudomonas aeruginosa and culture medium is 7:6:3:4:100.

[0052] Example 4: This example is basically the same as Example 1, except that the microbial agent is placed in the shaker and shaken for 15 minutes every 5 hours during the cultivation process.

[0053] Example 5: This example is basically the same as Example 1, except that the microbial agent is placed in the shaker and shaken for 25 minutes every 8 hours during the cultivation process.

[0054] Example 6: This example is basically the same as Example 1, except that the initial temperature of the shaker is 30°C, and the temperature of the shaker gradually decreases to 5°C during the shaking process.

[0055] Example 7: This example is basically the same as Example 1, except that the initial temperature of the shaker is 35°C, and the temperature of the shaker gradually decreases to 10°C during the shaking process.

[0056] Example 8: This example is basically the same as Example 1, except that the temperature of the shaker decreases at a rate of 2℃ / min during the shaking process.

[0057] Example 9: This example is basically the same as Example 1, except that the temperature of the shaker decreases at a rate of 3°C / min during the shaking process.

[0058] Example 10: This example is basically the same as Example 1, except that the culture medium composition by mass percentage includes: 0.5% glucose, 5% peptone, 1% sodium chloride, 0.2% vitamins, 5% arginine, 10% beef extract, 0.1% magnesium sulfate, 10% agar, and the remainder is deionized water.

[0059] Example 11: This example is basically the same as Example 1, except that the culture medium composition by mass percentage includes: 3% glucose, 10% peptone, 3% sodium chloride, 0.6% vitamins, 10% arginine, 20% beef extract, 0.3% magnesium sulfate, 15% agar, and the remainder is deionized water.

[0060] Example 12: This example is basically the same as Example 1, except that the mass ratio of mixed solution A to mixed solution B is 1:1.

[0061] Example 13: This example is basically the same as Example 1, except that the mass ratio of mixed solution A to mixed solution B is 1:1.5.

[0062] Example 14: This example is basically the same as Example 1, except that the mixed solution B is added to the mixed solution A in three equal parts.

[0063] Example 15: This example is basically the same as Example 1, except that the mixed solution B is added to the mixed solution A in 5 equal portions.

[0064] Example 16: The amount of tetrabutyl titanate added each time accounts for 30% of the mass of aluminum nitrate.

[0065] Example 17: The amount of tetrabutyl titanate added each time accounts for 40% of the mass of aluminum nitrate.

[0066] Comparative Example 1: Referring to Example 1, the microbial agent was a commercially available microbial repair agent mixed with the culture medium.

[0067] Comparative Example 2: Referring to Example 1, no shaking was used during the cultivation process.

[0068] Comparative Example 3: Referring to Example 1, the temperature of the shaker was kept constant at 32°C during the shaking process.

[0069] Comparative Example 4: Referring to Example 1, the temperature of the shaker decreased at a rate of 1°C / min during the shaking process.

[0070] Comparative Example 5: Referring to Example 1, the temperature of the shaker decreased at a rate of 4°C / min during the shaking process.

[0071] Comparative Example 6: Using Example 1 as a reference, commercially available microbial culture medium was used.

[0072] Comparative Example 7: Referring to Example 1, the mass ratio of mixed solution A to mixed solution B was 1:2.

[0073] Comparative Example 8: Referring to Example 1, all of the mixed solution B was added to mixed solution A at once.

[0074] Comparative Example 9: Referring to Example 1, the carrier used was pure chitosan gel.

[0075] Experimental Example: To investigate the remediation effects of each embodiment on soil, heavy metal contaminated soil from the same area was used as test fields for each embodiment. After 30 days of remediation, the copper, cadmium, and lead ion contents before and after remediation were measured in each test field. The reduction rates of copper, cadmium, and lead ion contents before and after remediation for each embodiment were calculated. The specific investigation is as follows:

[0076] 1. Investigating the influence of microbial inoculant components on the repair effect.

[0077] like Figure 1 As shown, a comparison of Examples 1, 2, and 3 reveals that the experimental field of Example 1 exhibited the highest reduction rates in copper, cadmium, and lead ion content. This may be because the microbial agent composition of Example 1 was reasonable, and the microorganisms were able to effectively exert synergistic effects, thus making the microbial agent composition of Example 1 optimal.

[0078] As can be seen from the comparison between Example 1 and Comparative Example 1, after replacing the microorganisms in the microbial agent with commercially available microbial remediation agents, the reduction rates of copper, cadmium, and lead ion content all decreased. Therefore, the microbial agent of Example 1 has a better remediation ability for heavy metal pollution than commercially available microbial remediation agents.

[0079] 2. Investigating the effect of shaking time on the repair effect.

[0080] like Figure 2 As shown, a comparison of Examples 1, 4, and 5 reveals that the experimental field of Example 1 exhibited the highest reduction rates in copper, cadmium, and lead ion content. This may be because the shaking time in Example 1 allowed the microbial agent to be evenly loaded onto the carrier, while avoiding damage to the microorganisms caused by the shaking time. Therefore, the shaking time selected in Example 1 was optimal.

[0081] A comparison of Example 1 and Comparative Example 2 shows that the reduction rate of copper, cadmium, and lead ion content decreased when no shaking was used during the cultivation process. This may be because shaking can make nutrients and microorganisms evenly distributed on the carrier. Therefore, the cultivation method selected in Example 1 is better.

[0082] 3. Investigate the effect of shaker temperature on the restoration effect.

[0083] like Figure 3 As shown, a comparison of Examples 1, 6, and 7 reveals that the experimental field of Example 1 exhibited the highest reduction rate in copper, cadmium, and lead ion content. This may be because the temperature in Example 1 can both reduce the pore size of the carrier and decrease the loss of microorganisms, while also preventing excessive reduction in microbial activity. Therefore, the shaker temperature selected in Example 1 was optimal.

[0084] A comparison of Example 1 and Comparative Example 3 shows that when the temperature of the shaker remained unchanged during the cultivation process, the reduction rates of copper, cadmium, and lead ion contents all decreased. This may be because lowering the temperature can reduce the pore size of the carrier after microbial loading, thereby reducing the loss of microorganisms. Therefore, the cultivation method selected in Example 1 is superior.

[0085] 4. Investigate the effect of the rate of temperature change of the shaker on the repair effect.

[0086] like Figure 4 As shown, a comparison of Examples 1, 8, and 9 with Comparative Examples 4 and 5 reveals that Example 1 exhibits the highest reduction rates in copper, cadmium, and lead ion content. This may be because lowering the temperature during cultivation can reduce the pore size of the carrier and decrease the loss of microorganisms. However, an excessively rapid temperature reduction rate can lead to a decrease in microbial activity. Therefore, the shaking temperature reduction rate selected in Example 1 is optimal.

[0087] 5. Investigate the effect of culture medium composition on repair efficacy.

[0088] like Figure 5 As shown, a comparison of Examples 1, 10, and 11 reveals that Example 1 exhibits the highest reduction rates in copper, cadmium, and lead ion content. This may be because the culture medium composition of Example 1 provides the nutrients required for microbial growth and proliferation, thus making the culture medium composition of Example 1 optimal.

[0089] As can be seen from the comparison between Example 1 and Comparative Example 6, after replacing the culture medium in Example 1 with a commercially available microbial culture medium, the reduction rate of copper, cadmium and lead ion content all decreased. This may be because the culture medium in Example 1 is more suitable for the microbial agent of this application and can provide sufficient nutrients for the microorganisms of this application. Therefore, the culture medium composition selected in Example 1 is better.

[0090] 6. Investigate the effect of the ratio of mixed solution A to mixed solution B on the repair effect.

[0091] like Figure 6 As shown, a comparison of Examples 1, 12, 13 and Comparative Example 7 reveals that Example 1 exhibits the highest reduction rates in copper, cadmium, and lead ion content. This may be because the chitosan / aluminum titanate composite gel prepared by the ratio of mixed solution A to mixed solution B in Example 1 has better stability, more pores, and can accommodate more microorganisms. Therefore, the ratio of mixed solution A to mixed solution B selected in Example 1 is superior.

[0092] 7. Investigate the effect of the number of times mixed solution B is added on the repair effect.

[0093] like Figure 7As shown in the comparison of Examples 1, 14, and 15, the reduction rate of copper, cadmium, and lead ion content in Example 1 is higher than that in Example 14. This may be because after adding mixed solution B in more stages, less tetrabutyl titanate is hydrolyzed, which can better exert the cross-linking effect and make the generated chitosan / aluminum titanate composite gel more stable. Compared with Example 15, the reduction rate of copper, cadmium, and lead ion content is not much different. Therefore, from the perspective of cost, the number of additions of mixed solution B in Example 1 is more optimal.

[0094] As can be seen from the comparison between Example 1 and Comparative Example 8, the reduction rate of copper, cadmium and lead ion content decreased after the mixed solution B was added all at once. This may be because the tetrabutyl titanate added when mixed solution B was added all at once underwent more hydrolysis, resulting in unstable chitosan / aluminum titanate composite gel properties, fewer internal pores, and inability to stably support microorganisms. Therefore, considering the time cost, the mixed solution B addition method selected in Example 1 is better.

[0095] 8. Investigate the effect of tetrabutyl titanate dosage on the repair effect.

[0096] like Figure 8 As shown in the comparison of Examples 1, 16, and 17, the reduction rate of copper, cadmium, and lead ion content in Example 1 is higher than that in Example 16. This may be because the amount of tetrabutyl titanate added in Example 1 can effectively play a cross-linking role and generate a stable chitosan / aluminum titanate composite gel. Compared with Comparative Example 17, the reduction rates of copper, cadmium, and lead ion content in Example 1 are not much different. Therefore, from a cost perspective, the amount of tetrabutyl titanate added in Example 1 is better.

[0097] As can be seen from the comparison between Example 1 and Comparative Example 9, the reduction rate of copper, cadmium and lead ion content decreased after using pure chitosan gel as a carrier. This may be because the chitosan / aluminum titanate composite gel has more internal pores, which can carry more microorganisms, and the chitosan / aluminum titanate composite gel can adsorb heavy metal ions, making heavy metal ions easier to be degraded by microorganisms.

Claims

1. A method for remediating contaminated soil based on microbial enhancement, characterized in that, Includes the following steps: S1. Add Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, and Pseudomonas aeruginosa to the culture medium and mix evenly to obtain a microbial agent. The mass ratio of Bacillus subtilis, Rhodopseudomonas palustris, Bacillus licheniformis, Pseudomonas aeruginosa, and culture medium is 5~7:3~6:2~3:2~4:80~100. S2. Immerse the carrier in 3-5 times its own weight of microbial inoculant and incubate at 30-35℃ for 1-3 days. During the incubation process, place the microbial inoculant in a shaker and shake for 15-25 minutes every 5-8 hours. The initial temperature of the shaker is 30-35℃, and the temperature of the shaker is gradually reduced to 5-10℃ during the shaking process. After the incubation is completed, remove the carrier to obtain the microbial-loaded carrier; the carrier is a chitosan / aluminum titanate composite gel. S3. Remove 5-10cm of soil from the area to be repaired, spread the carrier loaded with microorganisms into the soil, then backfill the soil in the area to be repaired and sprinkle water on the area to be repaired. The preparation method of the chitosan / aluminum titanate composite gel includes the following steps: Step 1: Dissolve aluminum nitrate in anhydrous ethanol and stir until the aluminum nitrate is completely dissolved to obtain mixed solution A; add chitosan to glacial acetic acid solution and stir until the chitosan is completely dissolved to obtain mixed solution B; the mass percentage of aluminum nitrate in mixed solution A is 2~4%, the mass percentage of chitosan in mixed solution B is 1~3%, and the mass ratio of mixed solution A to mixed solution B is 1:1~1.5; Step 2: Divide the mixed solution B into 3 to 5 portions and add it to the mixed solution A. After each addition of mixed solution B, stir the mixed solution A for 5 to 10 minutes. During the stirring process, continuously add tetrabutyl titanate to the mixed solution A. After each stirring, use ammonia water to adjust the pH of the mixed solution A to neutral. Step 3: After adding all of the mixed solution B, continue stirring the mixed solution A at 40~50℃ for 1~2 hours. After filtration and drying, chitosan / aluminum titanate composite gel is obtained.

2. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The culture medium comprises, by mass percentage: 0.5-3% glucose, 5-10% peptone, 1-3% sodium chloride, 0.2-0.6% vitamins, 5-10% arginine, 10-20% beef extract, 0.1-0.3% magnesium sulfate, 10-15% agar, with the remainder being deionized water.

3. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The shaking table has an amplitude of 20~30mm and a rotation speed of 100~150rpm.

4. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The rate at which the temperature of the shaking table decreases during the oscillation process is 2~3℃ / min.

5. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The amount of water sprayed is 3-6 liters per acre.

6. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The amount of the carrier loaded with microorganisms is 200-300g per acre.

7. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The mass concentration of the glacial acetic acid solution is 2-4%.

8. The method for remediating contaminated soil based on microbial enhancement according to claim 1, characterized in that, The amount of tetrabutyl titanate added each time accounts for 30-40% of the mass of aluminum nitrate.

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