Organic contaminated soil remediation method based on compound bacterium remediation agent

Abstract

The invention discloses an organic contaminated soil remediation method based on a compound bacterium remediation agent. The organic contaminated soil remediation method comprises the following steps: S1, biochar modification: FeCl3 and LaCl3. 7H2O modified biochar is obtained; s2, culturing compound bacteria, namely mixing the ectotrophic substance sphingosine bacterium suspension and the staphylococcus xylosus suspension in an equal volume manner to obtain a compound bacteria suspension, wherein the sphingosine bacterium suspension and the staphylococcus xylosus suspension are mixed in an equal volume manner; s3, immobilizing compound bacteria; and S4, soil remediation. Aiming at the soil jointly polluted by a plurality of organic polluted soils, two microbial bacteria which are relatively good in synergism and relatively good in degradation effect on organic pollutants are screened out as compound bacteria, and meanwhile, in order to further improve the action effect and activity of the compound bacteria, the compound bacteria are loaded on specific biochar through a series of means, so that the compound bacteria can be used for preparing the biochar. The activity can be further improved, so that the synergistic degradation of various organic pollutants in the soil is improved, and a good effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a method for remediating organic polluted soil based on a composite bacterial remediation agent. Background Art

[0002] Soil organic pollution refers to soil pollution caused by excessively high organic matter content in the soil. This type of pollution is mainly caused by artificially synthesized organic pollutants, such as organic waste and pesticides. Organic pollutants in the soil can be divided into easily degradable and difficult to decompose types according to their solubility. Easily degradable types include organophosphorus pesticides and trichloroacetaldehyde; difficult to decompose types include organochlorine, which remain in the soil for a long time, causing crop yield reduction, and remain in plants as plant residual toxins. The harm of soil organic pollution is serious. It not only endangers the growth of crops and the survival of soil organisms, but may also enter the human body through the food chain, bringing serious impacts on human survival and health.

[0003] Therefore, the control and remediation of soil organic pollution is of vital importance. At present, a variety of control or remediation methods have been developed at home and abroad, including physical remediation technology, chemical remediation technology and biological remediation technology. Among them, biological remediation has attracted people's attention due to its low cost, no secondary pollution, and large-scale application, and the treatment effect is relatively good.

[0004] For example, the invention patent with the patent authorization announcement number CN107580818B provides a comprehensive method for soil conditioning and repair, including: applying oyster shell powder, silicon calcium potassium magnesium fertilizer, biological organic fertilizer, biocontrol agent, and ternary compound fertilizer to the soil before planting crops or after fruit trees are picked; applying a large amount of elemental water-soluble fertilizer and humic acid water-soluble fertilizer to the soil before fruit trees sprout and bloom; applying silicon calcium potassium magnesium fertilizer and compound microbial liquid to the soil during the young fruit expansion period of fruit trees; applying high potassium fertilizer and seaweed fertilizer to the soil during the fruit tree fruiting period. This method can condition and repair the soil, which can make the soil pH tend to neutral and the acidification degree significantly reduced; the soil organic matter content is significantly increased, the soil becomes loose and breathable, and the soil layer is deep. The heavy metal content in the soil is reduced, which improves the safety of planting crops and increases the yield. The method of the present invention does not interrupt the growth of crops in the soil, and while conditioning and repairing the soil, it allows the crops to grow healthily and improves the quality of the crops, thereby ensuring the economic benefits of the growers. However, the effect of a single microbial agent or a composite agent is limited. Without a suitable carrier, the growth of microorganisms is easily affected by various external environments, especially the soil environment where various organic pollutants cross-contaminate each other, which can inhibit the activity of microorganisms. Therefore, how to improve the tolerance of microorganisms to multiple organic pollutants and select composite agents with better tolerance is a problem that needs to be solved at present. Summary of the invention

[0005] In view of the above-mentioned problems, the present invention provides a method for remediating organic contaminated soil based on a composite bacterial remediation agent.

[0006] The technical solution of the present invention is:

[0007] A method for remediating organic contaminated soil based on a composite bacterial remediation agent comprises the following steps:

[0008] S1. Biochar modification: FeCl3 powder and LaCl3·7H2O powder are mixed and added into deionized water to obtain a modifier, the modifier is mixed with biochar powder, and stirred to obtain a mixed solution, and the mixed solution is filtered and dried to obtain modified biochar;

[0009] The mass fraction of FeCl3 in the modifier is 0.8-1.5%, the mass fraction of LaCl3·7H2O powder in the modifier is 0.1-0.2%, and the mass fraction of biochar powder in the mixed solution is 0.6-0.9%;

[0010] S2. Composite bacteria culture: inoculate the xenobiotic sphingobacterium freeze-dried strain into the culture medium to obtain a xenobiotic sphingobacterium suspension, OD600=0.6-0.8, inoculate the xenobiotic staphylococcus freeze-dried strain into the culture medium to obtain a xenobiotic staphylococcus suspension, OD600=0.6-0.8, mix the xenobiotic sphingobacterium suspension and the xenobiotic staphylococcus suspension in equal volumes to obtain a composite bacteria suspension;

[0011] S3, fixing composite bacteria: the modified biochar prepared in S1 is mixed with the composite bacteria suspension prepared in S2, with a weight volume ratio of w:v of 1g:22-25ml, to obtain a base liquid, sodium alginate solution, lignin and calcium chloride solution are added in sequence, mixed and cross-linked for 10-12h, filtered and dried to obtain biochar with fixed composite bacteria;

[0012] The amount of sodium alginate solution added is 75-80% of the volume of the base liquid, the weight volume ratio of lignin added to the base liquid is 1g:60-70ml, and the amount of calcium chloride solution added is 75-80% of the volume of the base liquid;

[0013] S4, soil remediation: adding the biochar with fixed composite bacteria prepared in S3 to the organic contaminated soil, with the addition amount being 10-200 g / m 2 , turning and planting crops at the same time.

[0014] Furthermore, in S1, the FeCl3 powder and the LaCl3·7H2O powder are sieved through a 200-mesh sieve.

[0015] Note: The particle sizes of FeCl3 powder and LaCl3·7H2O powder are optimized to ensure uniform dissolution.

[0016] Furthermore, the drying temperature of the mixed liquid in S1 is 60-70°C.

[0017] Note: The good activity of the modified biochar is ensured by optimizing the drying temperature.

[0018] Furthermore, the biochar in S1 is cyanobacteria biochar, and the preparation method of the cyanobacteria biochar is:

[0019] After drying the cyanobacteria, soak them in a KOH solution with a mass concentration of 40% for 1 to 2 hours, take them out, dry them, grind them through a 200-mesh sieve, heat them to 700 to 800° C. under nitrogen protection and carbonize them for 1 to 2 hours, take them out, rinse them with deionized water, and dry them at 60 to 70° C. to obtain cyanobacteria biochar.

[0020] Description: By selecting cyanobacteria biochar as a carrier for loading composite bacteria, it has the ability to adsorb and degrade harmful substances in the environment, such as absorbing N2O, CO2, etc. At the same time, the pore structure is well developed, which can effectively load the composite bacteria and has good compatibility, thereby improving the soil's water storage capacity and water flow rate.

[0021] Furthermore, the xenobiotic sphingobacterium in S2 has a preservation number of CGMCC1.3639, which is preserved in the China Microbiological Culture Collection Center. The culture method of the xenobiotic sphingobacterium suspension is as follows:

[0022] The xenobiotic sphingobacterium freeze-dried strain is inoculated into LB culture medium with an inoculation loop, cultured in a constant temperature oscillator at 30-35°C and 150-200 rpm for 16-18 hours, then centrifuged at 3000-4000 rpm for 5-10 minutes, the supernatant is removed to obtain the strain, the strain is suspended with deionized water, the above process is repeated two to three times, and the OD value at 600-800 nm is measured with an ultraviolet spectrophotometer to obtain a xenobiotic sphingobacterium bacterial suspension with OD600=0.6-0.8.

[0023] Description: By selecting xenobiotic-eating sphingobacterium as one of the composite bacteria, it can play a major role in the degradation of organic matter in the soil and has functional genes for the degradation of soil organic pollutants.

[0024] Furthermore, the deposit number of the Staphylococcus aureus in S2 is CGMCC1.8022, which is deposited in the China Microbiological Culture Collection Center. The culture method of the Staphylococcus aureus suspension is:

[0025] The freeze-dried strain of Staphylococcus aureus was inoculated into LB culture medium with an inoculation loop, cultured in a constant temperature oscillator at 30-35°C and 150-200 rpm for 16-18 hours, then centrifuged at 3000-4000 rpm for 5-10 minutes, the strain was obtained after removing the supernatant, the strain was suspended with deionized water, the above process was repeated two to three times, and the OD value at 600-800 nm was measured with an ultraviolet spectrophotometer to obtain a Staphylococcus aureus suspension with OD600=0.6-0.8.

[0026] Description: By selecting Staphylococcus aureus as one of the composite bacteria, it can play an auxiliary role in the xenophagous sphingobacteria, reduce the impact of lignin on the xenophagous sphingobacteria, and at the same time transform it into conditions that are conducive to the degradation of organic pollutants, stimulating the activation of polyphenol oxidase and catalase in the soil.

[0027] Furthermore, the mass fraction of the sodium alginate solution in S3 is 2-4%, and the mass fraction of the calcium chloride solution is 1-3%.

[0028] Furthermore, the stirring depth in S4 is 8 to 10 cm.

[0029] Note: By optimizing the turning depth, the biochar with fixed composite bacteria is evenly distributed in the soil, especially near the root system of crops, to further improve the application effect.

[0030] Furthermore, the types of crops in S4 are one or more of rapeseed, cabbage or green vegetables.

[0031] Note: The selected crops are all common and easy-to-grow green crops, which play an auxiliary role in the degradation of soil organic matter and heavy metals.

[0032] The beneficial effects of the present invention are:

[0033] (1) The organic contaminated soil remediation method based on the composite bacterial remediation agent of the present invention is aimed at soils that are co-contaminated by multiple organic pollutants. Two microorganisms with good synergy and good degradation effects on organic pollutants are selected as composite bacteria. At the same time, in order to further improve the effect and activity of the composite bacteria, we load them on specific biochar through a series of means, which can further improve their activity, thereby improving the synergistic degradation of multiple organic pollutants in the soil, with good effects.

[0034] (2) The present invention is a method for remediating organic contaminated soil based on a composite bacteria remediation agent. The biochar loaded with composite bacteria is optimized, and cyanobacteria biochar is selected as the carrier for loading composite bacteria. The cyanobacteria biochar has the ability to adsorb and degrade harmful substances in the environment, has a well-developed pore structure, can effectively load composite bacteria, and has good compatibility. At the same time, the cyanobacteria biochar is modified, and FeCl3 and LaCl3 are loaded on the surface of the biochar to improve the binding of organic phosphorus pollutants in the soil, thereby reducing the impact of organic phosphorus pollutants on the degradation efficiency of other organic pollutants, thereby achieving a mutually reinforcing effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 is the degradation rate of soil organic phenanthrene pollutants by several test cases in Experimental Example 1 of the present invention;

[0036] Figure 2 is the degradation rate of soil organic phosphorus pollutants by several test cases in Experimental Example 2 of the present invention;

[0037] Figure 3 It is the synergistic degradation rate of soil organic phosphorus and organic phenanthrene pollutants in several test cases in Experimental Example 3 of the present invention. DETAILED DESCRIPTION

[0038] Example 1

[0039] A method for remediating organic contaminated soil based on a composite bacterial remediation agent comprises the following steps:

[0040] S1. Biochar modification: FeCl3 powder and LaCl3·7H2O powder are mixed and added into deionized water to obtain a modifier, the modifier is mixed with the biochar powder, and a mixture is obtained by stirring, the mixture is filtered and dried at 68°C to obtain modified biochar, and the FeCl3 powder and LaCl3·7H2O powder are sieved through a 200 mesh sieve;

[0041] Among them, the mass fraction of FeCl3 in the modifier is 1%, the mass fraction of LaCl3·7H2O powder in the modifier is 0.15%, and the mass fraction of biochar powder in the mixed solution is 0.7%;

[0042] The biochar is cyanobacteria biochar, and the preparation method of cyanobacteria biochar is as follows:

[0043] After drying the cyanobacteria, soaking them in a KOH solution with a mass concentration of 40% for 1.5 hours, taking them out, drying them, grinding them through a 200-mesh sieve, heating them to 750°C for carbonization treatment for 1.5 hours under nitrogen protection, taking them out, rinsing them with deionized water, and drying them at 65°C to obtain cyanobacteria biochar;

[0044] S2. Composite bacteria culture: inoculate the xenobiotic sphingobacterium lyophilized strain into the culture medium to obtain a xenobiotic sphingobacterium suspension, OD600=0.8, inoculate the xenobiotic staphylococcus lyophilized strain into the culture medium to obtain a xenobiotic staphylococcus suspension, OD600=0.8, mix the xenobiotic sphingobacterium suspension and the xenobiotic staphylococcus suspension in equal volumes to obtain a composite bacteria suspension;

[0045] The xenobiotic sphingobacterium has a preservation number of CGMCC1.3639 and is preserved in the China Microbiological Culture Collection Center. The culture method of the xenobiotic sphingobacterium suspension is as follows:

[0046] The xenobiotic Sphingobacterium lyophilized strain was inoculated into LB medium using an inoculation loop, cultured in a constant temperature oscillator at 32°C and 180 rpm for 17 h, then centrifuged at 3500 rpm for 8 min, the supernatant was removed to obtain the strain, the strain was suspended in deionized water, the above process was repeated two to three times, and the OD value at 800 nm was measured using an ultraviolet spectrophotometer to obtain a xenobiotic Sphingobacterium bacterial suspension with OD600=0.8.

[0047] The preservation number of Staphylococcus aureus is CGMCC1.8022, which is preserved in the China Microbiological Culture Collection Center. The culture method of Staphylococcus aureus suspension is as follows:

[0048] The lyophilized strain of Staphylococcus aureus was inoculated into LB medium with an inoculation loop, cultured in a constant temperature oscillator at 32°C and 180 rpm for 17 h, and then centrifuged at 3500 rpm for 8 min. The strain was removed from the supernatant and suspended in deionized water. The above process was repeated two to three times, and the OD value at 800 nm was measured with an ultraviolet spectrophotometer to obtain a suspension of Staphylococcus aureus with OD600=0.8.

[0049] S3, fixation of composite bacteria: the modified biochar prepared in S1 is mixed with the composite bacteria suspension prepared in S2, the weight volume ratio w:v of the two is 1g:24ml, and a base liquid is obtained, sodium alginate solution, lignin and calcium chloride solution are added in sequence, mixed and cross-linked for 11h, filtered and dried to obtain biochar with fixed composite bacteria;

[0050] The mass fraction of the sodium alginate solution is 3%, and the amount of the sodium alginate solution added is 77% of the volume of the base liquid. The weight volume ratio of the amount of lignin added to the base liquid is 1 g: 65 ml. The mass fraction of the calcium chloride solution is 2%, and the amount of the calcium chloride solution added is 77% of the volume of the base liquid.

[0051] S4, soil remediation: add the biochar with fixed composite bacteria prepared in S3 to the organic contaminated soil at an addition amount of 100 g / m 2The turning depth is 9cm, and crops are planted at the same time, and the types of crops are green vegetables.

[0052] Example 2

[0053] The difference between this embodiment and embodiment 1 is that:

[0054] S1. Biochar modification: The mixed solution was filtered and dried at 60° C. to obtain modified biochar, wherein the mass fraction of FeCl 3 in the modifier was 0.8%, the mass fraction of LaCl 3·7H 2 O powder in the modifier was 0.1%, and the mass fraction of biochar powder in the mixed solution was 0.6%.

[0055] Example 3

[0056] The difference between this embodiment and embodiment 1 is that:

[0057] S1. Biochar modification: The mass fraction of FeCl3 in the modifier is 1.2%, the mass fraction of LaCl3·7H2O powder in the modifier is 0.18%, and the mass fraction of biochar powder in the mixed solution is 0.8%.

[0058] Example 4

[0059] The difference between this embodiment and embodiment 1 is that:

[0060] S1. Biochar modification: The mass fraction of FeCl3 in the modifier is 1.5%, the mass fraction of LaCl3·7H2O powder in the modifier is 0.2%, and the mass fraction of biochar powder in the mixed solution is 0.9%.

[0061] Example 5

[0062] The difference between this embodiment and embodiment 1 is that:

[0063] The preparation method of cyanobacteria biochar is as follows:

[0064] After drying the cyanobacteria, soak them in a KOH solution with a mass concentration of 40% for 1 hour, take them out, dry them, grind them through a 200-mesh sieve, heat them to 700°C for carbonization treatment for 2 hours under nitrogen protection, take them out, rinse them with deionized water, and dry them at 60°C to obtain cyanobacteria biochar.

[0065] Example 6

[0066] The difference between this embodiment and embodiment 1 is that:

[0067] The preparation method of cyanobacteria biochar is as follows:

[0068] After drying the cyanobacteria, soak them in a KOH solution with a mass concentration of 40% for 2 hours, take them out, dry them, grind them through a 200-mesh sieve, heat them to 800°C for carbonization treatment for 1 hour under nitrogen protection, take them out, rinse them with deionized water, and dry them at 70°C to obtain cyanobacteria biochar.

[0069] Example 7

[0070] The difference between this embodiment and embodiment 1 is that:

[0071] S2. Composite bacteria culture: The lyophilized strain of xenobiotic Sphingobacterium was inoculated into the culture medium to obtain a xenobiotic Sphingobacterium bacterial suspension, OD600=0.6; the lyophilized strain of Staphylococcus aureus was inoculated into the culture medium to obtain a Staphylococcus aureus bacterial suspension, OD600=0.6;

[0072] The culture method of the xenobiotic-eating sphingobacterium suspension is as follows:

[0073] The xenobiotic Sphingobacterium lyophilized strain was inoculated into LB medium using an inoculation loop, cultured in a constant temperature oscillator at 30°C and 150 rpm for 18 h, then centrifuged at 3000 rpm for 10 min, the supernatant was removed to obtain the strain, the strain was suspended in deionized water, the above process was repeated two to three times, and the OD value at 600 nm was measured using an ultraviolet spectrophotometer to obtain a xenobiotic Sphingobacterium bacterial suspension with OD600=0.6.

[0074] The culture method of Staphylococcus aureus suspension is:

[0075] The freeze-dried strain of Staphylococcus aureus was inoculated into LB medium using an inoculation loop, cultured in a constant temperature oscillator at 30°C and 150 rpm for 18 h, then centrifuged at 3000 rpm for 10 min, the strain was obtained after removing the supernatant, and the strain was suspended in deionized water. The above process was repeated two to three times, and the OD value at 600 nm was measured using an ultraviolet spectrophotometer to obtain a Staphylococcus aureus suspension with OD600=0.6.

[0076] Example 8

[0077] The difference between this embodiment and embodiment 1 is that:

[0078] S2. Composite bacteria culture: The lyophilized strain of xenobiotic Sphingobacterium was inoculated into the culture medium to obtain a xenobiotic Sphingobacterium bacterial suspension, OD600=0.7; the lyophilized strain of Staphylococcus aureus was inoculated into the culture medium to obtain a Staphylococcus aureus bacterial suspension, OD600=0.7;

[0079] The culture method of the xenobiotic-eating sphingobacterium suspension is as follows:

[0080] The xenobiotic Sphingobacterium lyophilized strain was inoculated into LB medium using an inoculation loop, cultured in a constant temperature oscillator at 35°C and 200 rpm for 16 hours, and then centrifuged at 4000 rpm for 5 minutes. The strain was obtained after removing the supernatant, and the strain was suspended in deionized water. The above process was repeated two to three times, and the OD value at 700 nm was measured using an ultraviolet spectrophotometer to obtain a xenobiotic Sphingobacterium bacterial suspension with OD600=0.7.

[0081] The culture method of Staphylococcus aureus suspension is:

[0082] The freeze-dried strain of Staphylococcus aureus was inoculated into LB medium with an inoculation loop, cultured in a constant temperature oscillator at 35°C and 200 rpm for 16 h, then centrifuged at 4000 rpm for 5 min, the supernatant was removed to obtain the strain, the strain was suspended in deionized water, the above process was repeated two to three times, and the OD value at 700 nm was measured with an ultraviolet spectrophotometer to obtain a Staphylococcus aureus suspension with OD600=0.7.

[0083] Example 9

[0084] The difference between this embodiment and embodiment 1 is that:

[0085] S3, fixation of composite bacteria: the modified biochar prepared in S1 is mixed with the composite bacteria suspension prepared in S2, the weight volume ratio w:v of the two is 1g:22ml, and a base liquid is obtained, sodium alginate solution, lignin and calcium chloride solution are added in sequence, mixed and cross-linked for 10h, filtered and dried to obtain biochar with fixed composite bacteria;

[0086] Among them, the mass fraction of sodium alginate solution is 2%, the amount of sodium alginate solution added is 80% of the volume of the base liquid, the weight volume ratio w:v of the added amount of lignin and the base liquid is 1g:70ml, the mass fraction of calcium chloride solution is 1%, and the amount of calcium chloride solution added is 75% of the volume of the base liquid.

[0087] Example 10

[0088] The difference between this embodiment and embodiment 1 is that:

[0089] S3, fixation of composite bacteria: the modified biochar prepared in S1 is mixed with the composite bacteria suspension prepared in S2, the weight volume ratio w:v of the two is 1g:25ml, and a base liquid is obtained, sodium alginate solution, lignin and calcium chloride solution are added in sequence, mixed and cross-linked for 12h, filtered and dried to obtain biochar with fixed composite bacteria;

[0090] Among them, the mass fraction of sodium alginate solution is 4%, the amount of sodium alginate solution added is 75% of the volume of the base liquid, the weight volume ratio w:v of the added amount of lignin and the base liquid is 1g:60ml, the mass fraction of calcium chloride solution is 3%, and the amount of calcium chloride solution added is 80% of the volume of the base liquid.

[0091] Embodiment 11

[0092] The difference between this embodiment and embodiment 1 is that:

[0093] S4. Soil remediation: Add the biochar with fixed composite bacteria prepared in S3 to the organic contaminated soil at an addition amount of 10 g / m 2 The turning depth is 8cm, and crops are planted at the same time, the crop type is cabbage.

[0094] Example 12

[0095] The difference between this embodiment and embodiment 1 is that:

[0096] S4, soil remediation: Add the biochar with fixed composite bacteria prepared in S3 to the organic contaminated soil at an addition amount of 200 g / m 2 The turning depth is 10cm, and crops are planted at the same time, including rapeseed, cabbage and green vegetables.

[0097] Note: In actual soil remediation, the addition amounts in Example 1, Example 11 and Example 12 can be reasonably selected according to the degree of soil pollution.

[0098] Experimental Example 1

[0099] During the indoor test, we tested the organic contaminated soil remediation method based on the composite bacterial remediation agent of the present invention. 50 kg of test soil was taken, placed in a container with a laying depth of 12 cm, and evenly sprayed with an acetone solution containing organic phenanthrene, and the moisture content was adjusted to 20%, and the content of organic phenanthrene was 200 mg / kg. Then, the remediation was carried out according to the method in Example 1, and compared with the comparative example. In Comparative Example 1, the biochar was not modified, and the remaining steps were the same as in Example 1; in Comparative Example 2, a single xenobiotic sphingobacterium suspension was used, in Comparative Example 3, a single Bacillus subtilis suspension was used, and in Comparative Example 4, a single Taihu new sphingobacterium suspension was used, and the remaining steps were the same as in Example 1. The results are as follows: Figure 1 shown.

[0100] It can be seen that the method in Example 1 of the present invention has a significant effect on the degradation of organic phenanthrene pollutants in the soil. The biochar can fix the microbial agent to form particles, thereby adsorbing the pollutants to the surface or inside of the particles, and the embedded composite bacteria degrade and adsorb phenanthrene, forming a good degradation system.

[0101] In Comparative Example 1, the biochar was not modified, and its degradation efficiency was almost the same as that of Example 1. Therefore, under the condition of single pollutant phenanthrene, the effect of modified biochar was limited;

[0102] In Comparative Examples 2 to 4, we selected different single microbial functional bacteria. It can be seen that the effects of using single microbial functional bacteria are not as good as those in Example 1, which shows that the composite bacteria of the present invention have a stronger phenanthrene degradation function. By preferably using Staphylococcus aureus as one of the composite bacteria, it can play an auxiliary role in the xenobiotic sphingobacterium, reduce the influence of lignin on the xenobiotic sphingobacterium, and at the same time convert it into conditions that are conducive to the degradation of organic pollutants, stimulating the activation of polyphenol oxidase and catalase in the soil; at the same time, the synergistic effect of the xenobiotic sphingobacterium and the modified biochar in the present invention is also better than that of Bacillus subtilis and Taihu Neosphingobacterium.

[0103] Example 2

[0104] During the indoor test, we tested the organic contaminated soil remediation method based on the composite bacterial remediation agent of the present invention. 50 kg of test soil was taken, placed in a container with a laying depth of 12 cm, and evenly sprayed with an acetone solution containing organic phosphorus to adjust the moisture content to 20% and the organic phosphorus content to 200 mg / kg. Then, the soil was remediated according to the method in Example 1, and compared with the comparative example. In Comparative Example 1, the biochar was not modified, and the remaining steps were the same as in Example 1; in Comparative Example 2, a single xenobiotic-eating sphingobacterium suspension was used, in Comparative Example 3, a single Bacillus subtilis suspension was used, and in Comparative Example 4, a single Taihu new sphingobacterium suspension was used, and the remaining steps were the same as in Example 1. The results are as follows: Figure 2 shown.

[0105] It can be seen that the method in Example 1 of the present invention has a significant effect on the degradation of organic phosphorus pollutants in the soil, especially the modified biochar has a greater effect on its degradation. In Comparative Example 2 and Comparative Example 1, the biochar was not modified, and the degradation rate was quite different, because the biochar loaded with metal modified ions on the surface reacted with the organic phosphorus to generate new compounds attached to the surface of the biochar, and the embedded composite bacteria degraded and adsorbed the organic phosphorus to form a good degradation system; while the use of different strains had a smaller effect, but was still not higher than the composite bacteria;

[0106] Experimental Example 3

[0107] During the indoor test, we tested the organic contaminated soil remediation method based on the composite bacterial remediation agent of the present invention. 50 kg of test soil was taken, placed in a container with a laying depth of 12 cm, and evenly sprayed with an acetone solution containing organic phosphorus and organic phenanthrene, and the moisture content was adjusted to 20%. The contents of organic phenanthrene and organic phosphorus were both 200 mg / kg. Then, the soil was remediated according to the method in Example 1, and compared with the comparative example. In Comparative Example 1, the biochar was not modified, and the remaining steps were the same as in Example 1; in Comparative Example 2, a single xenobiotic sphingobacterium suspension was used, in Comparative Example 3, a single Bacillus subtilis suspension was used, and in Comparative Example 4, a single Taihu new sphingobacterium suspension was used, and the remaining steps were the same as in Example 1. The results are as follows: Figure 3 shown.

[0108] It can be seen that the method in Example 1 of the present invention has a significant effect on the degradation of organic phosphorus and organic phenanthrene pollutants in the soil. When organic phosphorus and organic phenanthrene pollutants appear in the soil at the same time, one of the pollutants will cause the adsorption and degradation of another pollutant by microorganisms and biochar, especially in Comparative Example 1, the biochar is not modified, which is further reduced compared with Experimental Examples 1 and 2. After adding modified biochar, FeCl3 and LaCl3 are loaded on the surface of biochar, which improves the binding of organic phosphorus pollutants in the soil, thereby reducing the effect of organic phosphorus pollutants on the degradation efficiency of other organic pollutants, thereby achieving a mutually reinforcing effect, because when organic pollutants phenanthrene and phosphorus coexist in the soil, they may interact or affect each other's environmental behavior. For example, the presence of phenanthrene may affect the activity of soil microorganisms, thereby affecting the decomposition rate of organic phosphorus; and the content and form of phosphorus may also affect the migration and transformation process of phenanthrene in the soil. At the same time, the composition of the composite bacteria is optimized, and the optimal composite bacteria composition in Example 1 is finally obtained.

Claims

1. A method for remediating organic contaminated soil based on a composite bacterial remediation agent, characterized in that: The following steps are involved: S1. Biochar modification: FeCl3 powder and LaCl3·7H2O powder are mixed and added into deionized water to obtain a modifier, the modifier is mixed with biochar powder, and stirred to obtain a mixed solution, and the mixed solution is filtered and dried to obtain modified biochar; The mass fraction of FeCl3 in the modifier is 0.8-1.5%, the mass fraction of LaCl3·7H2O powder in the modifier is 0.1-0.2%, and the mass fraction of biochar powder in the mixed solution is 0.6-0.9%; S2. Composite bacteria culture: inoculate the xenobiotic sphingobacterium freeze-dried strain into the culture medium to obtain a xenobiotic sphingobacterium suspension, OD600=0.6-0.8, inoculate the xenobiotic staphylococcus freeze-dried strain into the culture medium to obtain a xenobiotic staphylococcus suspension, OD600=0.6-0.8, mix the xenobiotic sphingobacterium suspension and the xenobiotic staphylococcus suspension in equal volumes to obtain a composite bacteria suspension; S3, fixing composite bacteria: the modified biochar prepared in S1 is mixed with the composite bacteria suspension prepared in S2, with a weight volume ratio of w:v of 1g:22-25ml, to obtain a base liquid, sodium alginate solution, lignin and calcium chloride solution are added in sequence, mixed and cross-linked for 10-12h, filtered and dried to obtain biochar with fixed composite bacteria; The amount of sodium alginate solution added is 75-80% of the volume of the base liquid, the weight volume ratio of lignin added to the base liquid is 1g:60-70ml, and the amount of calcium chloride solution added is 75-80% of the volume of the base liquid; S4, soil remediation: adding the biochar with fixed composite bacteria prepared in S3 to the organic contaminated soil, with the addition amount being 10-200 g / m 2 , turning and planting crops at the same time.

2. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: In S1, FeCl3 powder and LaCl3·7H2O powder are sieved through a 200-mesh sieve.

3. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The drying temperature of the mixed liquid in S1 is 60-70°C.

4. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The biochar in S1 is cyanobacteria biochar, and the preparation method of the cyanobacteria biochar is as follows: After drying the cyanobacteria, soak them in a KOH solution with a mass concentration of 40% for 1 to 2 hours, take them out, dry them, grind them through a 200-mesh sieve, heat them to 700 to 800° C. under nitrogen protection and carbonize them for 1 to 2 hours, take them out, rinse them with deionized water, and dry them at 60 to 70° C. to obtain cyanobacteria biochar.

5. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The xenobiotic sphingobacterium in S2 is deposited with the number CGMCC1.3639 in the China Microbiological Culture Collection Center. The culture method of the xenobiotic sphingobacterium suspension is as follows: The xenobiotic sphingobacterium freeze-dried strain is inoculated into LB culture medium with an inoculation loop, cultured in a constant temperature oscillator at 30-35°C and 150-200 rpm for 16-18 hours, then centrifuged at 3000-4000 rpm for 5-10 minutes, the supernatant is removed to obtain the strain, the strain is suspended with deionized water, the above process is repeated two to three times, and the OD value at 600-800 nm is measured with an ultraviolet spectrophotometer to obtain a xenobiotic sphingobacterium bacterial suspension with OD600=0.6-0.

8.

6. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The deposit number of the Staphylococcus aureus in S2 is CGMCC1.8022, which is deposited in the China Microbiological Culture Collection Center. The culture method of the Staphylococcus aureus suspension is as follows: The freeze-dried strain of Staphylococcus aureus was inoculated into LB culture medium with an inoculation loop, cultured in a constant temperature oscillator at 30-35°C and 150-200 rpm for 16-18 hours, then centrifuged at 3000-4000 rpm for 5-10 minutes, the strain was obtained after removing the supernatant, the strain was suspended with deionized water, the above process was repeated two to three times, and the OD value at 600-800 nm was measured with an ultraviolet spectrophotometer to obtain a Staphylococcus aureus suspension with OD600=0.6-0.

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7. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The mass fraction of the sodium alginate solution in S3 is 2-4%, and the mass fraction of the calcium chloride solution is 1-3%.

8. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The stirring depth in S4 is 8 to 10 cm.

9. The method for remediating organic contaminated soil based on a composite bacterial remediation agent according to claim 1, characterized in that: The crop types in S4 are one or more of rapeseed, cabbage or green vegetables.

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