JP7238228B1 - Combining rhamnolipids and earthworms to remediate dioxin-contaminated soil - Google Patents

Abstract

A method for remediation of dioxin-contaminated soil is provided, which has the advantages of high efficiency, green, environmentally friendly, low cost, simple process and easy operation.
The methods include the steps of fermenting and preparing rhamnolipids using Pseudomonas aeruginosa, obtaining earthworm seeds, pretreating contaminated soil, and mixing rhamnolipids with deionized water to prepare a rhamnolipid solution. forming a diversion channel and a supplementary substrate hole in the soil and introducing organic fertilizer into the supplementary substrate hole; and introducing earthworm seeds to treat and remediate the soil. and earthworms to remediate dioxin-contaminated soil.
[Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to the technical field of remediation of contaminated soil, and more particularly to a method of remediating dioxin-contaminated soil by combining rhamnolipids and earthworms.

Dioxins are persistent organic pollutants that are ubiquitous in the environment and are inadvertently generated as by-products from many chemical processes involving chlorine. As a natural reservoir of dioxins, soil enters the soil environment through various routes, such as dry and wet atmospheric deposition, application of organochlorine pesticides, agricultural use of sewage sludge, and waste deposition.

Dioxins in soil are extremely stable, decompose very slowly in the natural environment, and are persistent. Photodegradation, chemical decomposition, physical decomposition, and bioremediation are common as existing techniques for treating dioxins in soil. However, bioremediation is a soil remediation method that has received widespread attention in recent years because of its low consumption, high efficiency, and environmental friendliness. By isolating more efficient degrading strains and searching for degrading conditions, bioremediation is believed to play an important role in the treatment of soil dioxin contamination.

The method of remediation of dioxin-contaminated soil by combining rhamnolipids and earthworms is
S1, preparing a rhamnolipid;
fermenting and preparing rhamnolipids using Pseudomonas aeruginosa;
S2, obtaining earthworm species;
S3, pre-treating the soil;
After loosening the contaminated soil to be remedied and removing impurities, the surface is stirred to form a treatment layer, where the loosening depth is 30 to 50 cm,
S4, remediation of the soil;
S4-1, adding rhamnolipid solution Rhamnolipid was mixed with deionized water to prepare a rhamnolipid solution with a concentration of 300 to 1000 mg/L, and then rhamnolipid was applied to the treatment layer formed in S3 at an application rate of 2 to 3 L/m ² . applying the solution and loosening the soil again to uniformly mix the rhamnolipid solution and the soil;
S4-2, Soil retreatment S4-1 In the treatment layer after S4-1 treatment, the depth is 20-30 cm and the top width is 10-15 cm at intervals of 3-5 m.
, a diversion channel (1) having a vertical cross-sectional isosceles triangular structure with a bottom width of 5 to 8 cm is provided, and the diversion channel (1)
Auxiliary feeding base holes (2) with an inner diameter of 30 to 50 cm and a depth of 30 to 50 cm are provided at intervals of 8 to 10 m, and the auxiliary feeding base holes (2) have a volume of 40 to 60% of the volume of the auxiliary feeding base holes (2). by introducing organic fertilizer that occupies
S4-3, throwing earthworm seeds into contaminated soil at an injection density of 30 to 80/m ² ,
S4-4, treatment and remediation of soil The moisture content of the contaminated soil is maintained at 40-50% by the diversion channel (1). including 21-30 days repair at.
To explain, by installing a diversion channel, the water content of the contaminated soil is maintained in the early stage of the soil remediation treatment, and by providing supplemental feeding base holes and adding organic fertilizer, organic fertilizers are added to the soil during the water replenishment process of the diversion channel. Fertilizer penetration can be promoted.
As one aspect of the present invention, in step S1, the method of fermenting and preparing the rhamnolipid comprises:
S1-11, Pseudomonas aeruginosa after fermentation culture activation is put into the first liquid fermentation medium, the temperature is 35 to 37 ° C., and the vibration rotation speed is 230 to
Obtaining a fermentation liquid by fermenting and culturing for 4 to 7 days under the condition of 250 r / min;
S1-12, extracting rhamnolipids This includes centrifuging the fermented liquid under the condition of 7000-7500 r/min for 20-25 minutes to remove the fungus, taking the supernatant, and then extracting the rhamnolipids by an extraction method.
As one aspect of the present invention, in step S1-11, the components of the first liquid fermentation medium include 40 to 50 g/L of glycerol, 0.2 g/L of yeast paste, and 6.5 g of NaNO _{3 .}
/L _{, KH2PO4} 1.0 _g /L, NaCl 0.5 _g /L, _{Na2HPO4.12H2O}
1.0g / _{L , FeSO4.7H2O0.3g} /L, MgSO4.7H2O0.1g / _L
, containing 1000 ml of deionized water, pH=6.5-7.0.
As one aspect of the present invention, in step S1-12, as the extraction method, concentration 98%
Adjust the pH of the supernatant to 1 to 1.5 with sulfuric acid, and incubate at 4 to 8°C for 10 to 12 hours.
After allowing to stand still, extract an equal amount of the supernatant liquid with a chloroform-methanol mixture at a volume ratio of 2:1. Then, after standing and layer separation, the lower layer is taken, and the two extracts are combined and the solvent is evaporated to obtain rhamnolipid.
As another aspect of the present invention, in step S1, the method of fermenting and preparing the rhamnolipid comprises:
S1-21, Pseudomonas aeruginosa after activation of the fermentation culture is put into the second liquid fermentation medium, and the temperature is 28 to 32 ° C. and the number of vibration revolutions is 280 to
Obtaining a fermentation liquid by fermenting and culturing for 8 to 10 days under the condition of 300 r / min;
S1-22, rhamnolipid extraction involves centrifuging the fermented liquid for 25 to 30 minutes under the conditions of 5000 to 5500 r/min to remove the bacterial cells, taking the supernatant, and then extracting the rhamnolipids by membrane separation. .
Here, in step S1-21, the components of the second liquid fermentation medium include 100 soybean oil
~120g/L, yeast paste 0.2g/L, _NaNO3 6.5g/L, _KH2PO
4 1.0 g/L, NaCl 0.5 g/L, Na ₂ HPO _{4.12H 2} O 1.0 g/L, F
eSO ₄ 0.1 g/L, MgSO ₄ 0.3 g/L, deionized water 1000 ml, p
H=6.0-6.5.
Here, in step S1-22, as the membrane separation method, after diluting the fermentation broth 5 to 20 times using double distilled water, it is filtered at 25° C. with a filtration membrane having a molecular weight cutoff of 10,000 at 0.5°C. 5Mp
a, ultrafiltration under conditions of 200 to 300 L / h, then using a filtration membrane with a cutoff molecular weight of 300, the ultrafiltrate is subjected to nanofiltration under conditions of 25 ° C. and 1.0 MPa, and the solvent is Evaporate to obtain the rhamnolipid.
As one aspect of the present invention, the organic fertilizer is 40-50% livestock manure in terms of illumination mass %, 15-2
It is obtained by fermentation and preparation of 5% straw, 5-10% sawdust and the rest fallen leaves.
By way of explanation, livestock manure is specifically the manure of one or more domesticated livestock such as pigs, cattle, sheep, chickens, ducks, etc., and straw is specifically one of wheat, corn, rice, soybeans, etc. Sawdust and fallen leaves are not particularly limited, and livestock feces, straws, sawdust and fallen leaves are locally procured according to the region to reduce transportation costs.
As one aspect of the present invention, the fermentation method includes mixing straws, fallen leaves, and sawdust in the above proportions, pulverizing them, and then mixing them with livestock feces to obtain a mixed matrix; Add water until the water content reaches 40-50%, pile fermentation for 1-3 days, then turn over, cover with a plastic film and ferment continuously for 21-30 days, where:
Turn over every 3-5 days during the continuous fermentation process.
To explain, the vital activity of earthworms directly or indirectly affects the movement and alteration of contaminants in the soil, and the organic fertilizer prepared by this fermentation method effectively promotes the activity of earthworms, In this case, the fermenting agent is a commercially available organic fertilizer fermenting agent, and the specific amount used is according to the actual product guide standard.

Compared with the prior art, the present invention has the following beneficial effects. The whole process of the present invention is rational, combining rhamnolipids and earthworms can remediate dioxin-contaminated soil, effectively alter the metabolic pathways of microorganisms in the soil, and the addition of rhamnolipids as bioactive agents can reduce dioxins, etc. improve the bioavailability of pollutants, stimulate microbial response, the enzymes and dominant bacteria produced by earthworm activity can effectively decompose pollutants, high efficiency, green and environmentally friendly, It has advantages such as low cost, the added organic fertilizer nourishes the growth of earthworms and promotes the activity of earthworms, and the process of the present invention has the advantages of simple process and easy operation, so it can be widely used. Are suitable.

4 is a flow chart of the process of the present invention; FIG. 4 is a schematic diagram of the local structure of diversion channels and supplementary feeding holes in the treatment layer of the present invention; FIG. 4 is a local top view of the diversion channel and supplemental feeding hole in the treatment layer of the present invention; FIG. 4 is a local cross-sectional view of a diversion channel and supplementary feeding hole in the treatment layer of the present invention;

[Description of symbols]
1 diversion channel 2 supplementary feeding base hole

Example 1
The method for remediation of dioxin-contaminated soil by combining rhamnolipids and earthworms shown in FIG. 1 includes the following steps.
S1, Preparation of rhamnolipid S1-11, Pseudomonas aeruginosa after activation of the fermentation culture was put into the first liquid fermentation medium, and the temperature was 35° C. and the vibration speed was 230 r/mi.
fermented culture for 4 days under the conditions of n to obtain a fermented liquid, wherein the components of the first liquid fermentation medium include glycerol 40 g/L, yeast paste 0.2 g/L, NaNO ₃ 6.5 g/L , KH
_2PO4 1.0 _g / L , NaCl _0.5 g/L, _{Na2HPO4.12H2O 1.0} g/L
L, _FeSO4.7H2O 0.3 _g /L, _MgSO4.7H2O 0.1 _g /L, deionized water 1000 ml, pH=6.5,
S1-12, Rhamnolipid Extraction Fermented broth is centrifuged for 20 minutes under the condition of 7000 r/min to remove the fungus and the supernatant is taken. Adjust the pH of the supernatant to 1 with 98% sulfuric acid, leave at 4°C for 10 hours, extract an equal volume of the supernatant with a chloroform-methanol mixture at a volume ratio of 2:1, and leave at rest.・After stratification, take the lower layer, then extract the middle layer with a mixture of chloroform and methanol for a second time, leave it to stand and stratify, take the lower layer, combine the two extracts, and evaporate the solvent to remove the rhamnolipid. get,
S2, Acquisition of earthworm species Obtained mature Williams ringworms, free from disease and blemishes, with a well-defined ring shape and weighing 3.0±0.5 g,
S3, loosen the contaminated soil to be remedied before soil treatment, stir the surface after removing impurities, and form a treatment layer, where the loosening depth is 30 cm;
S4, soil remediation treatment S4-1, addition of rhamnolipid solution Rhamnolipid and deionized water were mixed and prepared to obtain ^a rhamnolipid solution with a concentration of 300 mg/L. applying the rhamnolipid solution in doses and loosening the soil again to evenly mix the rhamnolipid solution and the soil;
S4-2, Soil Retreatment As shown in Figures 2, 3 and 4, an isosceles triangular structure with a vertical cross-section of 20 cm depth, 10 cm top width and 5 cm bottom width was formed at intervals of 3 m in the treatment layer after S4-1 treatment. Diversion channel 1 is provided, and 8 m
Auxiliary feeding base holes 2 with an inner diameter of 30 cm and a depth of 30 cm are provided at intervals, and organic fertilizer having a volume of 40% of the auxiliary feeding base holes 2 is put into the auxiliary feeding base holes 2. The organic fertilizer is 40% by mass of the livestock. faeces, 15
% straw, 5% sawdust and the rest of fallen leaves are fermented and prepared, wherein the fermentation method is to mix straw, fallen leaves and sawdust in proportions, crush and then mix with livestock feces, Obtain a mixed matrix, add the fermenting agent to the mixed matrix, add water until the moisture content of the mixed matrix is 40%, turn over after 1 day of pile fermentation, cover with a plastic film and continuously ferment for 21 days Here, during the continuous fermentation process, it is turned over every 3 days, and the fermenting agent is a commercially available organic fertilizer fermenting agent, and the specific amount used is according to the actual product guide standards. It is possible,
S4-3, throwing earthworm seeds into contaminated soil at an injection density of 30 earthworm seeds/m ² ;
S4-4: The water content of the contaminated soil is maintained at 40% in the soil treatment and restoration diversion channel 1, and after 12 days of continuous restoration under conditions where this water content is maintained, restoration is performed for 21 days under natural conditions. .

Example 2
The method for remediation of dioxin-contaminated soil by combining rhamnolipids and earthworms shown in FIG. 1 includes the following steps.
S1, preparation of rhamnolipid S1-11, Pseudomonas aeruginosa after activation of the fermentation culture was put into the first liquid fermentation medium, and the temperature was 36° C. and the vibration speed was 240 r/mi.
Fermentation culture is performed for 4 to 7 days under the conditions of n to obtain a fermentation broth, wherein the components of the first liquid fermentation medium include 45 g/L of glycerol, 0.2 g/L of yeast paste, and 6.5 g of NaNO _{3 .} /L,
_KH2PO4 1.0 _g / L, NaCl 0.5 _g /L, _{Na2HPO4.12H2O 1.0}
g/L, _{0.3 g} /L FeSO4.7H2O , _{0.1 g} /L MgSO4.7H2O , 1000 ml deionized water, pH=6.8,
S1-12, rhamnolipid extraction Fermented liquid was centrifuged for 22 minutes under the condition of 7300 r/min to remove the microbial cells, and the supernatant was taken. The pH of the supernatant was adjusted to 1.3 using 98% sulfuric acid, and after standing at 5°C for 11 hours, an equal volume of the supernatant was extracted with a chloroform-methanol mixture at a volume ratio of 2:1. , Leave to stand and separate layers, then take the lower layer, then extract the middle layer with a mixture of chloroform and methanol for a second time, leave to stand and separate layers, take the lower layer, combine the two extracts, and evaporate the solvent. to obtain rhamnolipids,
S2, Acquisition of earthworm species Obtained mature Williams ringworms, free of disease and wounds, with a well-defined ring shape and weighing 3.0±0.5 g,
S3, loosen the contaminated soil to be remedied before soil treatment, stir the surface after removing impurities, and form a treatment layer, where the loosening depth is 40 cm;
S4, Soil Remediation Treatment S4-1, Rhamnolipid Solution Input Rhamnolipid and deionized water were mixed and prepared to obtain a rhamnolipid solution with a concentration of 500 mg/L ^. Apply the rhamnolipid solution at an application rate of , loosen the soil again to uniformly mix the rhamnolipid solution and the soil,
S4-2, soil retreatment As shown in Figs.
A diversion channel 1 having an isosceles triangular vertical cross-section with a top width of 12 cm and a bottom width of 6 cm is provided. 50% of the volume of the feeding base hole 2 is fed with organic fertilizer, and the organic fertilizer is 45% by mass of livestock feces.
It is obtained by fermenting and preparing 0% straw, 8% sawdust and the rest of fallen leaves, wherein the fermentation method is to mix straw, fallen leaves and sawdust in proportions, crush and then mix with livestock feces. , to obtain a mixed matrix, add the fermenting agent to the mixed matrix, add water until the moisture content of the mixed matrix is 45%, turn over after 2 days of pile fermentation, cover with plastic film and continue to ferment for 28 days. , where it is turned over every 4 days during the continuous fermentation process, the fermenting agent is a commercially available organic fertilizer fermenting agent, and the specific amount used is according to the actual product guide standards. can be
S4-3, throwing earthworm seeds into the contaminated soil at an injection density of 60 earthworm seeds/m ² ,
S4-4, the water content of the contaminated soil is maintained at 45% by the treatment and restoration of the soil diversion channel 1, and under the condition that this water content is maintained, 1
After 2 days of continuous repair, 28 days of repair under natural conditions.

Example 3
The method for remediation of dioxin-contaminated soil by combining rhamnolipids and earthworms shown in FIG. 1 includes the following steps.
S1, preparation of rhamnolipid S1-11, Pseudomonas aeruginosa after activation of the fermentation culture was added to the first liquid fermentation medium, and the temperature was 37° C. and the vibration speed was 250 r/mi.
fermented culture for 7 days under the condition of n to obtain a fermented liquid, wherein the components of the first liquid fermentation medium include glycerol 50 g/L, yeast paste 0.2 g/L, NaNO ₃ 6.5 g/L , KH
_2PO4 1.0 _g / L , NaCl _0.5 g/L, _{Na2HPO4.12H2O 1.0} g/L
L, _FeSO4.7H2O 0.3 _g /L, _MgSO4.7H2O 0.1 _g /L, deionized water 1000 ml, pH=7.0,
S1-12, Rhamnolipid Extraction Fermented liquid was centrifuged for 25 minutes under the condition of 7500 r/min to remove the fungus and the supernatant was taken. The pH of the supernatant was adjusted to 1.5 using 98% sulfuric acid, and after standing at 8°C for 12 hours, an equal amount of the supernatant was extracted with a chloroform-methanol mixture at a volume ratio of 2:1. , Leave to stand and separate layers, then take the lower layer, then extract the middle layer with a mixture of chloroform and methanol for a second time, leave to stand and separate layers, take the lower layer, combine the two extracts, and evaporate the solvent. to obtain rhamnolipids,
S2, Acquisition of earthworm species Obtained mature Williams ringworms, free of disease and wounds, with a well-defined ring shape and weighing 3.0±0.5 g,
S3, loosen the contaminated soil to be remedied before soil treatment, stir the surface after removing impurities, and form a treatment layer, where the loosening depth is 50 cm;
S4, Soil Remediation Treatment S4-1, Rhamnolipid Solution Input Rhamnolipid and deionized water were mixed and prepared to obtain ^a rhamnolipid solution with a concentration of 1000 mg/L. applying the rhamnolipid solution in doses and loosening the soil again to evenly mix the rhamnolipid solution and the soil;
S4-2, Soil Retreatment As shown in Figs. 2, 3 and 4, an isosceles triangular structure with a vertical cross-section of 30 cm depth, 15 cm top width and 8 cm bottom width was placed at intervals of 5 m in the treatment layer after S4-1 treatment. Diversion channel 1 is provided, and 8 to 8
An auxiliary feeding base hole 2 having an inner diameter of 50 cm and a depth of 50 cm is provided at intervals of 10 m, and organic fertilizer having a volume of 60% of the auxiliary feeding base hole 2 is put into the auxiliary feeding base hole 2. The organic fertilizer is 50% by mass of livestock. feces,
It is obtained by fermentation and preparation of 25% straw, 10% sawdust and the rest of fallen leaves, wherein the fermentation method is to mix straw, fallen leaves and sawdust in proportions, crush and then mix with livestock feces, Obtaining a mixed matrix, adding a fermenting agent to the mixed matrix, adding water until the moisture content of the mixed matrix is 50%, inverting after pile fermentation for 3 days, covered with a plastic film and continuously fermenting for 30 days, Here, it is turned over every 5 days during the continuous fermentation process, and the fermenting agent is a commercially available organic fertilizer fermenting agent. can
S4-3, throwing earthworm seeds into contaminated soil at an injection density of 80 earthworm seeds/m ² ;
S4-4, the water content of the contaminated soil is maintained at 50% by the soil treatment and restoration diversion channel 1, and under the condition that this water content is maintained, 1
After 2 days of continuous repair, 30 days of repair under natural conditions.

Example 4
Different from Example 1 in the following points,
In step S1, the method of fermenting and preparing rhamnolipids includes the following steps.
S1-21, the Pseudomonas aeruginosa after activation of the fermentation culture is put into the second liquid fermentation medium, and the temperature is 28° C. and the vibration speed is 280 r/mi.
Fermentation culture is performed for 8 days under the conditions of n to obtain a fermented liquid, wherein the components of the second liquid fermentation medium include 100 g/L of soybean oil, 0.2 g/L of yeast paste, and 6.5 g/L _{of NaNO3.} , _KH2P
O4 1.0 g /L, NaCl _0.5 g/L, _{Na2HPO4.12H2O 1.0} g/L,
FeSO ₄ 0.1 g/L, MgSO ₄ 0.3 g/L, 1000 ml deionized water,
pH = 6.0,
S1-22, rhamnolipid extraction Fermented liquid was centrifuged for 25 minutes under the condition of 5000 r/min to remove the bacterial cells and the supernatant was taken, and then the rhamnolipids were extracted by the membrane separation method. , After diluting the fermented liquid 5 times with double distilled water, use a filtration membrane with a molecular weight cut off of 10000 at 25 ° C., 0
. After ultrafiltration treatment under conditions of 5 Mpa and 200 L/h, the ultrafiltrate was subjected to nanofiltration treatment under conditions of 25 ° C. and 1.0 Mpa using a filtration membrane with a cutoff molecular weight of 300, and the solvent was evaporated. Obtain rhamnolipid.

Example 5
Different from Example 2 in the following points,
In step S1, the method of fermenting and preparing rhamnolipids includes the following steps.
S1-21, the Pseudomonas aeruginosa after activation of the fermentation culture is put into the second liquid fermentation medium, and the temperature is 30° C. and the vibration speed is 290 r/mi.
Fermentation culture is performed for 9 days under the conditions of n to obtain a fermented liquid, wherein the components of the second liquid fermentation medium include 110 g/L of soybean oil, 0.2 g/L of yeast paste, and 6.5 g/L _{of NaNO3} . , _KH2PO
4 1.0 g/L, NaCl 0.5 g/L, Na ₂ HPO _{4.12H 2} O 1.0 g/L, F
eSO ₄ 0.1 g/L, MgSO ₄ 0.3 g/L, deionized water 1000 ml, p
H = 6.3,
S1-22, rhamnolipid extraction Fermented liquid was centrifuged for 28 minutes under the condition of 5200 r/min to remove the bacterial cells and the supernatant was taken, then the rhamnolipids were extracted by the membrane separation method. , After diluting the fermentation liquid 15 times with double distilled water, use a filtration membrane with a molecular weight cut off of 10000 at 25 ° C.,
After ultrafiltration treatment under conditions of 0.5 Mpa and 250 L/h, the ultrafiltrate was subjected to nanofiltration treatment under conditions of 25 ° C. and 1.0 Mpa with a filtration membrane with a cutoff molecular weight of 300, and the solvent was evaporated. Obtain rhamnolipid.
Example 6
Different from Example 3 in the following points,
In step S1, the method of fermenting and preparing rhamnolipids includes the following steps.
S1-21, Pseudomonas aeruginosa after activation of the fermentation culture is put into the second liquid fermentation medium, the temperature is 32 ° C., and the number of vibration revolutions is 280 to 300.
Fermented culture was performed for 10 days under the condition of r/min to obtain a fermented liquid, wherein the components of the second liquid fermentation medium were 120 g/L of soybean oil, 0.2 g/L of yeast paste, and 6.5 g _{of NaNO3} . /L,
_KH2PO4 1.0 _g / L, NaCl 0.5 _g /L, _{Na2HPO4.12H2O 1.0}
g/L, _FeSO4 0.1 g/L, _MgSO4 0.3 g/L, 1000 ml deionized water, pH=6.5,
S1-22, the rhamnolipid extraction fermentation liquid is centrifuged for 30 minutes under the condition of 5500 r/min to remove the bacterial cells and the supernatant is taken, and then the rhamnolipids are extracted by the membrane separation method. , After diluting the fermentation broth 20 times with double distilled water, use a filtration membrane with a molecular weight cut off of 10000 at 25 ° C.,
After ultrafiltration under conditions of 0.5 Mpa and 300 L/h, the ultrafiltrate was subjected to nanofiltration under conditions of 25°C and 1.0 Mpa using a filtration membrane with a cutoff molecular weight of 300, and the solvent was evaporated. to obtain rhamnolipids.

Experimental Example A strain of Pseudomonas aeruginosa with number ATCC15442 was purchased from a Shanghai Biotechnology Co., Ltd., rhamnolipid prepared in step S1 of Example 1 was prepared, and mixed with deionized water to give a rhamnolipid concentration of 300 mg/L. prepare a solution,
Purchasing earthworms from an earthworm farming company in Huai'an, Jiangsu, obtaining earthworm seeds according to step S2 of Example 1,
Primitive soil was collected from a waste gas steelworks in Hefei City, Anhui Province.
Collected at a depth of 20 cm, dried and passed through a 2 mm sieve to obtain primitive soil, HRGC/HR
Detecting a dioxin concentration of 4.61 ng / kg in primitive soil by MS ultratrace analysis,
The organic fertilizer was obtained by fermenting and preparing 40% cow dung, 15% wheat straw, 5% sawdust and the balance pine needles, where the fermenting agent is Feed Approval No./Registration No. (2
015) 2335 commercially available fermentation agents,
Five sets of treatment experiments were set up:
1st experimental group, 5000g primitive soil,
2nd experimental group, 5000g primitive soil + 5 earthworm seeds,
3rd set of experiments, 5000g pristine soil + 10ml rhamnolipid solution,
4th experimental set, 5000g pristine soil + 5 earthworm seeds + 3ml rhamnolipid solution,
5th experimental group, 5000g pristine soil + 5 earthworm seeds + 3ml rhamnolipid solution + 2g organic fertilizer,
In each set of experiments, after 12 days of continuous remediation under the condition that the water content of the contaminated soil was kept at 40%,
21 days of remediation under natural conditions, taking 5 g soil samples every 3 days for biomass analysis with the results shown in Table 1;

Table 1: Biomass analysis results of 21-day soil samples from five sets of treatment experiments.

Conclusion: As can be seen from the biomass analysis results of the 21-day soil samples of the first experimental set, the first
By retaining 40% of the maximum water holding capacity of the soil for 2 days, the dioxin in the soil was diluted so that the dioxin concentration in the soil sample was slightly lower than the dioxin concentration in the pristine soil,
As can be seen from the first experimental group, the second experimental group, the third experimental group, the fourth experimental group, and the fifth experimental group, the fourth
The experimental group and the fifth experimental group exhibited a relatively effective decomposition effect on dioxin in the soil, where the decomposition rate of the fifth experimental group was 90.6%, which is the WHO soil dioxin meets the control standard of 0.60 ng/kg of
As can be seen from the 1st, 2nd and 3rd experimental groups, rhamnolipids and earthworms have a relatively large effect on the decomposition of dioxin.
As can be seen from the second, fourth and fifth experimental groups, the rhamnolipid solution can effectively promote the decomposition efficiency of dioxins in the soil by earthworms.
As can be seen from the 4th and 5th experimental groups, the addition of organic fertilizer promotes the decomposition effect of dioxin, and this is thought to be because the organic fertilizer effectively promotes the activity of earthworms. ing.

Claims (3)

step S1,
fermenting and preparing a rhamnolipid using Pseudomonas aeruginosa to prepare the rhamnolipid;
step S2,
obtaining earthworm seeds;
step S3,
pretreating the contaminated soil to be remedied, loosening the contaminated soil, removing impurities and then agitating the surface to form a treatment layer, wherein the loosening depth is 30-50 cm;
step S4,
Step S4-1, adding rhamnolipid solution Rhamnolipid and deionized water were mixed to prepare a rhamnolipid solution with a concentration of 300 to 1000 mg/L, and then applied to the treatment layer formed in S3 at an application rate of 2 to 3 L/m ² . Applying the rhamnolipid solution, loosening the soil again to uniformly mix the rhamnolipid solution and the soil,
Step S4-2, Soil Retreatment Step S4-1 In the treatment layer after the treatment, a depth of 20 to 30 cm and a top width of 10 to 3 m are applied at intervals of 3 to 5 m.
A diversion channel (1) having an isosceles trapezoid structure in vertical section with a width of 15 cm and a bottom width of 5 to 8 cm is provided, and the diversion channel (
In 1), supplementary feeding holes with an inner diameter of 30 to 50 cm and a depth of 30 to 50 cm are placed at intervals of 8 to 10 m (2).
is provided, and an organic fertilizer occupying 40 to 60% of the volume of the auxiliary feeding base hole (2) is put into the auxiliary feeding base hole (2),
step S4-3, throwing earthworm seeds into the contaminated soil at an injection density of 30 to 80/m ² of earthworm seeds;
Step S4-4, treatment and remediation of the soil The moisture content of the contaminated soil is maintained at 40-50% by the diversion channel (1), and after continuous remediation for 12 days under the condition of maintaining this moisture content, natural conditions remediation of the soil under remediation for 21-30 days;
A method of remediating dioxin-contaminated soil by combining rhamnolipids and earthworms, comprising: The organic fertilizer is 40-50% by mass of livestock feces, 15-25% straw, 5-10%
2. Process according to claim 1, characterized in that it is obtained by fermentation and preparation of sawdust and residual leaf litter. As the fermentation method, straws, fallen leaves, and sawdust are mixed in the above proportions, pulverized, and then mixed with livestock feces to obtain a mixed matrix. Add water to 1-3 days, turn over after 1-3 days, cover with plastic film and ferment continuously for 21-30 days, 3-3 during the continuous fermentation process
3. A method according to claim 2, characterized by inverting every 5 days.

Images