Electric reinforced remediation method for organic contaminated soil

Abstract

The invention relates to an electric enhanced remediation method for organic contaminated soil, which comprises the following steps: step 1, according to the condition of the contaminated soil, determining original functional microbial flora and functional plants suitable for an electric field condition; 2, domesticating the original functional microbial flora according to the condition of the functional plant to obtain a functional microbial flora; step 3, determining current enhanced binary window conditions of the functional microbial flora and the functional plants; step 4, constructing an electric enhanced ecological pile system; 5, after the functional plants germinate for a set number of days, the electric enhanced ecological pile system starts to conduct power-on restoration treatment, and in the restoration process, the current intensity of the longitudinal electric field and the current intensity of the transverse electric field are controlled according to the current enhanced binary window conditions determined in the step 3. According to the invention, the functional microbial flora and the functional plants suitable for the electric field condition are simultaneously applied to the electric enhanced ecological pile system, so that the remediation effect of the organic contaminated soil is optimized.

Description

Technical Field

[0001] The present invention relates to the field of remediation of organically contaminated soil, and particularly to an electrokinetic enhanced remediation method for organically contaminated soil. Background Art

[0002] At present, for the treatment of many types of organically contaminated soil, a variety of feasible remediation methods that have been applied in engineering disposal have been developed, such as soil replacement dilution technology, incineration technology, soil washing technology, chemical oxidation-reduction technology, thermal desorption technology, co-disposal technology with cement kilns, bioremediation technology, etc. Among them, bioremediation technology is one of the earliest known, studied and engineered remediation technologies due to its advantages such as economy, environmental friendliness and convenient operation.

[0003] The bioremediation technology for organically contaminated soil includes various methods such as microbial remediation, phytoremediation and zooremediation. Among them, microbial remediation and phytoremediation have been further promoted due to their successful cases and experiences of large-scale application. However, in the existing engineering disposal evaluations, microbial remediation and phytoremediation generally have defects such as low remediation efficiency, large fluctuations in remediation ability, and being extremely vulnerable to the natural environment and weakening or even losing the remediation ability. In response to the above problems, a variety of enhanced means of bioremediation have been explored and tried in the prior art, such as biostimulation methods mainly based on nutrient supply, and tillage agronomic regulation means mainly based on enhanced supply of electron acceptors. However, for the disposal objects with relatively heavy soil texture, the mass transfer processes of nutrients and soil gases in the soil will be greatly restricted, which will seriously affect the high efficiency of microbial remediation and the stability of continuous remediation, and become one of the key problems restricting its further expansion of application value and increase in remediation market share.

[0004] As a classic effective remediation method for contaminated clayey soil, electrokinetic remediation technology is widely used for the removal of heavy metal pollutants in soil. However, for the degradation of organic pollutants, for complex organic compounds with high activation energy requirements, its electrochemical oxidation potential is not enough to break the energy barrier, so the obtained degradation effect is relatively limited, and there is a large room for improvement in remediation efficiency. Therefore, how to combine electrokinetic remediation with bioremediation technology, use the electrokinetic effect to assist soil mass transfer and improve the metabolic remediation efficiency by stimulating biological physiological activity, and achieve the coupling of the remediation process is an issue that needs to be considered in the prior art.

[0005] At present, the electrokinetic enhanced microbial remediation technology has been studied in depth and has been well applied in the remediation practice of demonstration projects such as polycyclic aromatic hydrocarbon-, petroleum-, and organic pesticide-contaminated soils. In addition, the research on electrokinetic enhanced phytoremediation has also developed to a certain extent, and it has been found that some functional plants that assist in the degradation of organic matter have the potential to grow under direct current stimulation. However, the phytoremediation process usually mainly relies on rhizosphere microorganisms. There is no report in the existing technology on how to combine exogenous functional microorganisms with the rhizosphere microenvironment of plants, and then construct a rhizosphere synthetic functional microenvironment with a highly efficient pollutant-degrading functional microbial community as the main body and maintain the composition and function stability of the functional microbial community through the rhizosphere microenvironment. Further, in view of the potential of both functional microorganisms and functional plants for electrokinetic enhancement, how to simultaneously complete the stimulation and enhancement of the two by current, so as to further maintain the stability of biodegradation activity, is also an important research direction at present. In current research, the effective current intensity range for electroactivating microorganisms is called the "window condition" of electro-tolerant microorganisms and has been reported, but the research on the effective current intensity for stimulating functional plants remains to be explored. At the same time, the "dual-window condition" for the synergistic stimulation of functional microorganisms and functional plants also needs to be further explored. Summary of the Invention

[0006] The object of the present invention is to provide an electrokinetic enhanced remediation method for organic contaminated soil, which simultaneously applies a functional microbial flora and functional plants suitable for electric field conditions to an electrokinetic enhanced ecological heap system, and with the aid of the effective current stimulation determined by the electrokinetic enhancement dual-window condition, can maximize the stability of the functional microenvironment in the electrokinetic enhanced ecological heap system under the stable soil mass transfer system of the electrokinetic enhanced ecological heap system, thereby optimizing the remediation effect of organic contaminated soil.

[0007] The object of the present invention is achieved by the following technical solutions:

[0008] An electrokinetic enhanced remediation method for organic contaminated soil includes the following steps:

[0009] Step 1: According to the situation of the contaminated soil, determine the original functional microbial flora and functional plants suitable for electric field conditions;

[0010] Step 2: Domesticate the original functional microbial flora according to the situation of the functional plants to obtain a functional microbial flora;

[0011] Step 3: Determine the electrokinetic enhancement dual-window condition of the functional microbial flora and functional plants;

[0012] Step 4: Construct an electrokinetic enhanced ecological heap system, specifically:

[0013] Step 4.1: Inoculate the functional microbial flora into a culture medium for cultivation, and then inoculate it into the actually contaminated soil. The microbial abundance of the actually contaminated soil after inoculation is required to reach the set value X3.

[0014] Step 4.2: Stack a buffer layer, and arrange a buffer solution supply pipe horizontally in the buffer layer and a longitudinal anode vertically. Then stack the actually contaminated soil obtained in Step 4.1 on the buffer layer to form a main heap body. A longitudinal cathode is arranged vertically at the upper end of the main heap body. A longitudinal electric field is formed between the longitudinal anode and the longitudinal cathode. A first sidewall electrode is arranged on one lateral side of the main heap body and a second sidewall electrode is arranged on the other lateral side. A lateral electric field is formed between the first sidewall electrode and the second sidewall electrode. A supply pipeline is vertically arranged in the middle of the main heap body laterally, and a gas guide pipeline is horizontally arranged in the middle in the height direction.

[0015] Step 4.3: Plant functional plants on the upper surface and each sidewall of the main heap body.

[0016] Step Five: After the set number of days for the functional plants to germinate, the electrokinetic enhanced ecological heap system starts the electrokinetic remediation treatment, and during the remediation process, control the current intensities of the longitudinal electric field and the lateral electric field according to the current enhancement dual-window conditions determined in Step Three.

[0017] Step Two is specifically as follows:

[0018] Step 2.1: Obtain the original functional microbial flora.

[0019] Step 2.2: Inoculate the original functional microbial flora obtained in Step 2.1 into the simulated contaminated soil. The microbial abundance of the simulated contaminated soil after inoculation is required to reach the set value X1.

[0020] Step 2.3: Load the simulated contaminated soil obtained in Step 2.2 into the electrokinetic domestication device (1), plant functional plants, and then carry out electrokinetic domestication treatment. After domestication is completed, collect the rhizosphere soil of the functional plants and process it to form a functional microbial flora.

[0021] In Step 2.3, the electrokinetic domestication device includes an anode electrode chamber, a domestication chamber, and a cathode electrode chamber arranged in sequence, and there are conductive salt bridge joints between the anode electrode chamber and the domestication chamber and between the cathode electrode chamber and the domestication chamber.

[0022] Step 2.3 is specifically as follows:

[0023] Step 2.3.1: Load real clean soil into both the anode electrode chamber and the cathode electrode chamber, and load the simulated contaminated soil obtained in Step 2.2 into the domestication chamber. Then supplement water to the clean soil and the simulated contaminated soil until the saturated water content is reached.

[0024] Step 2.3.2: Plant functional plants in the acclimation chamber according to the set density;

[0025] Step 2.3.3: After the set germination time of the functional plants, insert the acclimation anode into the anode electrode chamber and insert the acclimation cathode into the cathode electrode chamber;

[0026] Step 2.3.4: Start the constant current power supply system to energize the acclimation anode and the acclimation cathode, and use the cyclic current method to conduct acclimation treatment on the simulated contaminated soil in the acclimation chamber;

[0027] The specific cyclic current method is as follows: within the set current intensity range, at the set current intensity interval, first gradually increase the current intensity and then gradually decrease the current intensity, and repeat this cycle until the total cycle period reaches the set time;

[0028] Step 2.3.5: Collect the rhizosphere soil of the functional plants;

[0029] Step 2.3.6: Treat the rhizosphere soil obtained in Step 2.3.5 to finally obtain the domesticated functional microbial flora.

[0030] Step three is specifically as follows:

[0031] Step 3.1: Inoculate the functional microbial flora into the culture medium for cultivation, and then inoculate it into the simulated contaminated soil. The microbial abundance of the inoculated simulated contaminated soil is required to reach the set value X2;

[0032] Step 3.2: Use the electric acclimation device for detection. The electric acclimation device includes an anode electrode chamber, an acclimation chamber, and a cathode electrode chamber arranged in sequence, and there are conductive salt bridge joints between the anode electrode chamber and the acclimation chamber and between the cathode electrode chamber and the acclimation chamber. The simulated contaminated soil obtained in Step 3.1 is loaded into the acclimation chamber, and the anode electrode chamber and the cathode electrode chamber are respectively loaded with real clean soil, and water is added to the clean soil and the simulated contaminated soil to reach the saturated water content;

[0033] Step 3.3: Plant functional plants in the acclimation chamber according to the set density;

[0034] Step 3.4: After the set germination time of the functional plants, insert the acclimation anode into the anode electrode chamber and insert the acclimation cathode into the cathode electrode chamber;

[0035] Step 3.5: Start the constant current power supply system to energize the domesticated anode and the domesticated cathode, and sequentially conduct power-on treatment on the simulated contaminated soil at a set number of current intensities, with power-on for a set number of days T at each current intensity. And within each set number of days T, detect the soil enzyme activity of the rhizosphere soil of the functional plants and the plant physiological characteristic indexes of the functional plants at different time points;

[0036] Step 3.6: Determine the functional microorganism window conditions according to the soil enzyme activities determined in Step 3.5, determine the functional plant window conditions according to the plant physiological characteristic indexes determined in Step 3.5, and then obtain the current-enhanced dual window conditions according to the functional microorganism window conditions and the functional plant window conditions.

[0037] Step 3.6 specifically is:

[0038] Step 3.6.1: For the functional microorganism flora, measure the soil enzyme activities at different time points respectively. Each soil enzyme includes dehydrogenase, catalase, protease, urease, β-glucosidase, alkaline phosphatase, lipase, sucrase, peroxidase, soil cellulase;

[0039] Step 3.6.2: For the functional plants, measure the plant physiological characteristic indexes at different time points respectively. Each plant physiological characteristic index includes plant height, root length, fresh weight of aboveground biomass, fresh weight of underground biomass and chlorophyll content;

[0040] Step 3.6.3: According to the soil enzyme indexes obtained in Step 3.6.1, calculate the microbial single activation index of each soil enzyme index at each time node. According to the plant physiological characteristic indexes obtained in Step 3.6.2, calculate the plant single activation index of each plant physiological characteristic index at each time node;

[0041] Step 3.6.4: According to the microbial single activation index of the soil enzyme index at each time node, obtain the microbial comprehensive biological activation index by calculating the mean value. And the current intensity range formed by the current intensity corresponding to the maximum microbial comprehensive biological activation index and its adjacent minimum current intensity constitutes the functional microorganism window conditions;

[0042] According to the plant single activation index of the plant physiological characteristic index at each time node, obtain the plant comprehensive biological activation index by calculating the mean value. And the current intensity range formed by the current intensity corresponding to the maximum plant comprehensive biological activation index and its adjacent minimum current intensity constitutes the functional plant window conditions;

[0043] The calculation of the microbial comprehensive biological activation index and the plant comprehensive biological activation index is the same, and both are calculated according to the following formula:

[0044]

[0045] In the above formula, is the comprehensive biological activation index, n is the number of biological indices, and m is the number of time nodes;

[0046] Step 3.6.5: Obtain the current-enhanced dual window condition according to the functional microorganism window condition and the functional plant window condition, specifically:

[0047] Define the functional microorganism window condition as WCM, the functional plant window condition as WCP, and the current-enhanced dual window condition as Dual-WC. Then the value range of Dual-WC is:

[0048] I. When Then there is:

[0049] Dual-WC ∈ [Dual-WC min , Dual-WC max = min(WCM, WCP);

[0050] II. When Then there is:

[0051] Dual-WC ∈ [Dual-WC min , Dual-WC max = WCM ∩ WCP;

[0052] Where is the empty set, Dual-WC min , Dual-WC max are the minimum and maximum values of Dual-WC respectively, min(WCM, WCP) is the minimum value of WCM and WCP, and WCM ∩ WCP is the intersection of WCM and WCP.

[0053] In Step 3.6.3, the calculation processes of the microorganism single activation index and the plant single activation index are the same, specifically:

[0054] Specify BAV i j to represent the biological activity value of the i-th biological index at the j-th time node. BAV i Ref represents the biological activity value of the i-th biological index at the initial time node as the reference sample value. RBAV i j represents the relative biological activity value of the i-th biological index at the j-th time node and is calculated according to the following formula:

[0055] RBAV ij =(BAV i j -BAV i Ref ) / BAV i Ref ;

[0056] or

[0057] RBAV i j =(BAV i Ref -BAV i j ) / BAV i Ref ;

[0058] The RBAV obtained by calculation i j Further calculate to obtain a single activation index value with reference to the criteria and assignment methods in the following table

[0059]

[0060] In Step 4.2, the longitudinal anode and the longitudinal cathode are respectively connected to a constant-direction power supply system through corresponding wires; the first sidewall electrode and the second sidewall electrode have opposite polarities and are respectively connected to a reverse-polarity power supply system through corresponding wires, the supply pipeline is connected to the reverse-polarity power supply system through a supply pipeline anode wire, and the supply pipeline is always the anode.

[0061] In Step Five, the longitudinal electric field and the transverse electric field operate alternately, and when the current intensities of the longitudinal electric field and the transverse electric field are lower than the lower limit value of the current enhancement dual-window condition, the supply pipeline starts to supply the inorganic salt solution until the current intensities of the longitudinal electric field and the transverse electric field reach the upper limit value of the current enhancement dual-window condition, and the supply pipeline stops supplying.

[0062] In Step Five, when the microbial abundance in the soil of the main body of the pile decreases to a set value, the supply pipeline starts to supply the functional microbial flora, and after the supply, the reverse-polarity power supply system supplies power to the supply pipeline to make the supply pipeline the anode. After the power supply reaches the set time, the reverse-polarity power supply system disconnects the power supply to the supply pipeline; when the soil pH value of the main body of the pile decreases, the buffer solution supply pipe starts to supply the buffer solution.

[0063] In Step 4.2:

[0064] The filling medium in the buffer layer is composed of conductive carbon black and clean soil mixed in a set ratio, and a set amount of buffer solution is added at the same time;

[0065] Each side wall of the main body of the heap forms a 70° angle with the bottom, and a retaining fiber mesh with a grid density of 0.5 per cm is arranged on the surface of each side wall; 2 of the retaining fiber mesh;

[0066] The upper end of the supply pipeline is connected to the supply storage tank through a supply connection pipeline, and a supply pump is provided on the supply connection pipeline. The lower end of the supply pipeline is sealed, and supply holes are evenly distributed on the supply pipeline;

[0067] The gas guiding pipeline is respectively connected to the corresponding interfaces on a gas guiding multi-way joint. The gas guiding multi-way joint is connected to an aeration pump through a gas guiding connection pipeline, and gas holes are evenly distributed on the gas guiding pipeline;

[0068] The buffer solution supply pipeline is respectively connected to the corresponding interfaces on a buffer solution multi-way joint. The buffer solution multi-way joint is connected to a buffer solution storage tank through a buffer solution connection pipeline, and a buffer solution pump is provided on the buffer solution connection pipeline. Buffer solution holes are evenly distributed on the buffer solution supply pipeline;

[0069] A thermometer is provided in the main body of the heap.

[0070] The advantages and positive effects of the present invention are:

[0071] 1. Aiming at the problem that the traditional microbial remediation technology cannot continuously and efficiently remediate, the present invention combines exogenous functional microbial flora with the rhizosphere microenvironment of functional plants, constructs a root synthetic functional microenvironment that maintains the composition and function stability of functional microbial flora with highly efficient pollutant-degrading functional microbial flora as the main body, and combines the rhizosphere environment of functional plants at the same time. Therefore, the electrokinetic enhanced ecological heap system constructed by the present invention can integrate the plant rhizosphere and the activity of functional microorganisms, promote the stable reproduction of functional microbial flora, and at the same time has the effect of promoting the physiological and metabolic activities of functional microorganisms and functional plants, thereby enhancing the continuous and efficient degradation ability of functional microorganisms.

[0072] 2. According to the electrokinetic enhancement potential of functional microbial flora and functional plants, the present invention uses the "comprehensive biological activation index method" to determine the window conditions of functional microorganisms and the window conditions of functional plants respectively, and then obtains the current enhancement dual window conditions according to the window conditions of functional microorganisms and the window conditions of functional plants. In this way, during the remediation process, effective current stimulation of functional microorganisms and functional plants can be achieved, and at the same time, under the stable soil mass transfer system of the electrokinetic enhanced ecological heap system, the stability of the functional microenvironment in the electrokinetic enhanced ecological heap system can be maintained to the greatest extent.

[0073] 3. When the electrokinetic enhanced ecological reactor system of the present invention remediates the soil, a longitudinal electric field and a transverse electric field will be formed, and the longitudinal electric field and the transverse electric field control the current intensity according to the current-enhanced dual-window condition. Once the current intensity does not meet the requirements, the present invention can adjust by supplementing the inorganic salt solution through the supply pipeline, and the adjustment control is simple and convenient.

[0074] 4. The longitudinal electric field in the electrokinetic enhanced ecological reactor system of the present invention forms an electroosmotic flow from bottom to top in the soil, which can effectively inhibit the tendency of water in the soil heap to accumulate downward due to gravity. This not only avoids the lack of soil moisture caused by the differential distribution of moisture in the heap soil, but also avoids problems such as current attenuation and non-continuous electrokinetic remediation process caused by insufficient moisture, thus being more conducive to the continuous progress of the current stimulation effect.

[0075] 5. The lower part of the longitudinal electric field in the electrokinetic enhanced ecological reactor system of the present invention is set as the anode, and the present invention can effectively supply oxygen to the bottom of the heap through the oxygen production process of the gas pipeline, thereby realizing the aeration treatment of the heap and alleviating the insufficient oxygen partial pressure at the bottom of the heap.

[0076] 6. The transverse electric field in the electrokinetic enhanced ecological reactor system of the present invention can achieve the inverted pole control with continuously changing polarities on both sides through the inverted pole power supply system, and then realize the control of the change of the transverse electric field direction. Combined with the action of the longitudinal electric field and the anode of the supply pipeline, it can perform a three-dimensional and all-round migration of the soluble components in the soil, and then promote the transport of the root exudates of the functional plants to the non-rhizosphere area of the heap soil. This has a good effect on stimulating the rhizosphere microenvironment of the functional plants in various parts of the heap, solves the limitation of the traditional rhizosphere environment being limited to the surface of the plant roots, and can effectively promote the metabolism and colonization of the functional microorganisms in the whole heap soil using the root exudates, thus being conducive to the continuous and efficient degradation of organic pollutants.

[0077] 7. The electrokinetic enhanced ecological reactor system of the present invention uses the buffer solution supply pipe in the buffer layer to supply buffer solution to the soil to control the moisture content of the buffer layer medium within the range of 13% - 16%. And it can also keep the overall pH value of the soil in the main body of the heap above 6.3. Under this weak acidic condition, the physiological activity of the functional microorganism flora will basically not be interfered. Description of the Drawings

[0078] Figure 1 It is a schematic flow chart of the method of the present invention.

[0079] Figure 2 It is a schematic structural diagram of the electrokinetic domestication device adopted in the embodiment of the present invention.

[0080] Figure 3 It is a schematic diagram of the window conditions of the functional microorganisms obtained in the embodiment of the present invention.

[0081] Figure 4 Schematic diagram of the window conditions of the functional plant obtained in the embodiment of the present invention

[0082] Figure 5 Schematic diagram of the current-enhanced dual-window conditions obtained according to the comprehensive biological activation index of microorganisms and the comprehensive biological activation index of plants in the embodiment of the present invention

[0083] Figure 6 Schematic diagram of the structure of the electric-enhanced ecological reactor system adopted in the embodiment of the present invention

[0084] Figure 7 is Figure 6 Schematic diagram of the internal composition of the electric-enhanced ecological reactor system in

[0085] Figure 8 is Figure 7 Top view of the internal composition of the electric-enhanced ecological reactor system in

[0086] Figure 9 is Figure 8 View A-A in

[0087] Figure 10 is Figure 8 View B-B in

[0088] Figure 11 is Figure 6 Schematic diagram of the change in current intensity during soil remediation by the electric-enhanced ecological reactor system in

[0089] Figure 12 is Figure 6 Schematic diagram of the change in soil moisture content during soil remediation by the electric-enhanced ecological reactor system in

[0090] Figure 13 is Figure 6 Schematic diagram of the change in microbial abundance during soil remediation by the electric-enhanced ecological reactor system in

[0091] Figure 14 is Figure 6 Schematic diagram of the change in soil pH value during soil remediation by the electric-enhanced ecological reactor system in

[0092] Figure 15 is Figure 6 Schematic diagram of the change in PAHs residue during soil remediation by the electric-enhanced ecological reactor system in

[0093] Among them, 1 is an electric domestication device, 101 is a domestication chamber, 102 is an anode electrode chamber, 1021 is a domestication anode, 103 is a cathode electrode chamber, 1031 is a domestication cathode, 104 is a salt bridge joint, 105 is a constant current power supply system, 106 is a functional microorganism, 107 is a functional plant, 2 is an electric enhanced ecological reactor system, 201 is a reactor body main body, 202 is a buffer layer, 203 is a gas guide pipeline, 2031 is an aeration pump, 2032 is a gas guide connecting pipe, 2033 is a gas guide multi-way joint, 2034 is an air vent hole, 204 is a buffer solution supply pipe, 2041 is a buffer solution storage tank, 2042 is a buffer solution pump, 2043 is a buffer solution multi-way joint, 2044 is a buffer solution hole, 205 is a longitudinal anode, 2051 is a longitudinal anode wire, 206 is a longitudinal cathode, 2061 is a longitudinal cathode wire, 207 is a first side wall electrode, 208 is a reverse electrode power supply system, 209 is a supply pipeline, 2091 is a supply storage tank, 2092 is a supply connecting pipeline, 2093 is a supply pump, 2094 is a supply hole, 210 is a thermometer, 211 is a supply pipeline anode wire, 212 is a constant direction power supply system, 213 is a second side wall electrode, 214 is a side wall electrode wire. Detailed implementation manners

[0094] The present invention will be further described in detail below with reference to the accompanying drawings.

[0095] As Figures 1 - 15 shown, the present invention includes the following steps:

[0096] Step 1: According to the situation of the polluted soil, determine the original functional microorganism flora and functional plants suitable for the electric field conditions.

[0097] In this embodiment, a functional microenvironment for electric enhanced ecological reactor repair is constructed around PAHs-polluted soil. According to the above-mentioned polluted soil type, the original functional microorganism in this embodiment is a functional microorganism flora isolated from the polluted soil of a coking plant, and the functional plant adopts ryegrass plants.

[0098] Step 2: Domestication treatment is carried out on the original functional microorganism flora according to the situation of the functional plants to obtain a functional microorganism flora, specifically:

[0099] Step 2.1: Obtain the original functional microorganism flora.

[0100] In this embodiment, the original functional microorganism used is a functional microorganism flora isolated from the polluted soil of a certain coking plant, and its acquisition process is a well-known technology in the art. Specifically in this embodiment: 5 g of polluted soil is dispersed in 100 mL of sterile water, shaken at room temperature for 30 minutes, then left standing for 10 minutes, and 100 μL of the upper turbid liquid is taken and inoculated on nutrient agar (3 g·L -1 beef extract, 10 g·L -1 peptone, 5 g·L-1 In a sodium chloride medium, shake culture at a temperature of 30 °C and a rotation speed of 180 rpm for 36 hours in a culture device, and then centrifuge to collect the bacterial cells. The centrifugal culture device is a well-known technology in the art and is a commercially available product. Then, resuspend the bacterial cells in an inorganic salt liquid medium (0.2 g·L -1 of MgSO4·7H2O, 0.02 g·L -1 of CaCl2, 0.002 g·L -1 of FeSO4·7H2O, 1.5 g·L -1 of Na2HPO4·12H2O, 0.4 g·L -1 of K2HPO4, 0.01 g·L - 1 MnSO4·H2O, 1.0 g·L -1 prepared from NH4NO3, pH 7.0), and take 100 μL of the resuspended bacterial liquid and inoculate it into an inorganic salt liquid medium containing 150 mg·L -1 phenanthrene, 100 mg·L -1 pyrene, 10 mg·L -1 benzo[a]pyrene, and shake and ferment culture in a culture device at a temperature of 30 °C and a rotation speed of 180 rpm for 120 hours. Then, centrifuge to collect the bacterial cells and resuspend them again in the above inorganic salt liquid medium to obtain the original functional microbial community.

[0101] Step 2.2: Inoculate the original functional microbial community obtained in Step 2.1 into the simulated contaminated soil, and the microbial abundance of the inoculated simulated contaminated soil needs to reach the set value X1.

[0102] In this example, the original functional microbial community obtained in Step 2.1 was inoculated into a simulated contaminated soil composed of quartz sand, 0.8% (W / W) humic acid, and 150 mg·L -1 phenanthrene, 100 mg·L -1 pyrene, and 10 mg·L -1 benzo[a]pyrene. The microbial abundance of the inoculated simulated contaminated soil needs to reach X1 = 1.3×10 8 CFU·g -1 .

[0103] Step 2.3: Load the simulated contaminated soil in Step 2.2 into the electric domestication device 1, plant the functional plant 107, and perform electric domestication treatment. After domestication is completed, collect the rhizosphere soil of the functional plant 107 and process it to form a functional microbial community.

[0104] As Figure 2As shown in the figure, in this embodiment, the electric domestication device 1 includes an anode electrode chamber 102, a domestication chamber 101, and a cathode electrode chamber 103 arranged in sequence. The anode electrode chamber 102 is provided with a domestication anode 1021, and the cathode electrode chamber 103 is provided with a domestication cathode 1031. The domestication anode 1021 and the domestication cathode 1031 are respectively connected to a constant current power supply system 105 through wires. Conductive salt bridge connectors 104 are provided at the upper ends of the partitions between the anode electrode chamber 102 and the domestication chamber 101 and between the cathode electrode chamber 103 and the domestication chamber 101. The conductive salt bridge connectors 104 are used to achieve conductive connection between the domestication chamber 101 and the anode electrode chamber 102 and the cathode electrode chamber 103. In this embodiment, the conductive salt bridge connectors 104 use a potassium chloride salt bridge of 1.0 mol·L -1 to achieve conductive connection.

[0105] The specific process of this step is as follows:

[0106] Step 2.3.1: As Figure 2 shown, the anode electrode chamber 102 and the cathode electrode chamber 103 are both filled with real clean soil, and the simulated contaminated soil obtained in step 2.2 is filled into the domestication chamber 101. Then, water is added to the clean soil and the simulated contaminated soil to make the soil reach the saturated water content.

[0107] Step 2.3.2: As Figure 2 shown, the selected functional plant 107 is planted in the domestication chamber 101 at a set density. In this embodiment, the functional plant 107 is ryegrass. Before planting the ryegrass seeds, they are soaked in water for 3 days for rehydration treatment, and then the surface moisture of the seeds is blotted dry with filter paper. Then, they are planted at a density of 30 ug·cm -2 .

[0108] Step 2.3.3: After the functional plant 107 germinates for a set time, the domestication anode 1021 is inserted into the anode electrode chamber 102, and the domestication cathode 1031 is inserted into the cathode electrode chamber 103. In this embodiment, when the ryegrass germinates for 5 days, the domestication anode 1021 and the domestication cathode 1031 are respectively inserted.

[0109] Step 2.3.4: Start the constant current power supply system 105 and use the cyclic current method to conduct electrified domestication treatment on the simulated contaminated soil in the domestication chamber 101.

[0110] The cyclic current method is as follows: within the set current intensity range, the current intensity is first gradually increased and then gradually decreased at a set current intensity interval, and this process is repeated until the total cycle period reaches the set time.

[0111] In this embodiment, the current intensity is gradually increased starting from a power-on current of 5 mA, and the overall current range is 5 - 200 mA, with each 5 mA as a current intensity interval. The treatment duration at each current intensity is 0.6 hours. After the current intensity is increased to 200 mA, it is gradually decreased from 200 mA to 5 mA in steps and reciprocated until the total domestication period lasts for 30 days.

[0112] Step 2.3.5: Collect the rhizosphere soil of functional plant 107.

[0113] In this embodiment, after the domestication is completed, take the whole ryegrass plant. After stripping the loose soil from the roots, place the whole roots of the ryegrass plant in a self-sealing bag and shake it continuously to collect the rhizosphere soil. As Figure 2 shown, the rhizosphere soil includes functional microorganism 106.

[0114] Step 2.3.6: Treat the rhizosphere soil obtained in Step 2.3.5 to finally obtain the domesticated functional microorganism flora. The treatment process is a well-known technology in the art. Specifically in this embodiment: First, disperse the rhizosphere soil obtained in Step 2.3.5 by shaking in a phosphate buffer solution, then let it stand for 5 minutes and suck the upper turbid liquid into a new tube for standby. Sequentially prepare Nycodenz separation solutions with concentrations of 5%, 10%, 15%, 20%, and 25%. Add the above-mentioned concentrations of Nycodenz separation solutions to a 50 mL centrifuge tube in sequence, and then carefully add the turbid liquid after soil dispersion to the surface of the 5% Nycodenz solution. Centrifuge the mixture at 12,000 rpm for 45 minutes under refrigeration conditions, suck the cell solutions in different concentration Nycodenz solution layers and mix them into a new tube, and wash the microbial cells with a phosphate buffer solution to remove the Nycodenz solution, finally obtaining the domesticated functional microorganism flora. The functional microorganism flora and the functional plant (ryegrass) can cooperate to form a functional microenvironment that is mutually adaptable and adaptable to current stimulation and has the ability to degrade PAHs.

[0115] Step Three: Determine the current enhancement dual-window conditions for the functional microorganism flora and the functional plant.

[0116] As can be seen from the above Step Two, the functional biological materials in this embodiment include a functional microorganism flora and a functional plant with the ability to degrade polycyclic aromatic hydrocarbons, electric field adaptability, and rhizosphere mutual adaptability characteristics. In this step, the electric domestication device 1 shown in Figure 2 can still be used to analyze and measure the above-mentioned functional biological materials, and then determine the current enhancement dual-window conditions for the functional microorganism flora and the functional plant. Specifically:

[0117] Step 3.1: Inoculate the functional microbial community into a culture medium for cultivation, and then inoculate it into the simulated contaminated soil. After inoculation, the microbial abundance of the simulated contaminated soil needs to reach the set value X2.

[0118] In this embodiment, the functional microbial community is inoculated into a nutrient broth liquid medium and cultured for 48 hours. After collecting the bacterial cells, they are resuspended in an inorganic salt liquid medium, and then inoculated into the simulated contaminated soil composed of quartz sand, 0.8% (W / W) humic acid, 150 mg·L -1 phenanthrene, 100 mg·L -1 pyrene, and 10 mg·L -1 benzo[a]pyrene. After inoculation, the microbial abundance of the simulated contaminated soil needs to reach X2 = 3.7×10 8 CFU·g -1 . Additionally, before inoculation, the simulated contaminated soil needs to be sterilized at 121 °C for 30 minutes.

[0119] Step 3.2: Load the simulated contaminated soil obtained in Step 3.1 into the acclimation chamber 101 of the electric acclimation device 1. The anode electrode chamber 102 and the cathode electrode chamber 103 are filled with real clean soil, and water is added to both the clean soil and the simulated contaminated soil to make the soil reach the saturated water content.

[0120] Step 3.3: Plant the functional plant 107 in the acclimation chamber 101 at the set density. The functional plant 107 is ryegrass. Before planting the ryegrass seeds, they are soaked in water for 3 days for rehydration treatment, and then the surface moisture of the seeds is blotted dry with filter paper and planted at a density of 30 μg·cm -2 .

[0121] Step 3.4: After the functional plant 107 germinates for the set time, the acclimation anode 1021 is inserted into the anode electrode chamber 102, and the acclimation cathode 1031 is inserted into the cathode electrode chamber 103. In this embodiment, when the ryegrass germinates for 5 days, the acclimation anode 1021 and the acclimation cathode 1031 are inserted respectively.

[0122] Step 3.5: Start the constant current power supply system 105 and adopt the constant current power-on mode to conduct power-on treatment on the simulated contaminated soil in the acclimation chamber 101 in sequence with a set number of current intensities. At each current intensity, power is supplied for the set number of days T, and within the range of the set number of days T, the soil enzyme activity of the rhizosphere soil of the functional plant 107 and the plant physiological characteristic indexes of the functional plant 107 are detected at different time points respectively.

[0123] In this embodiment, after starting the constant-current power supply system 105, at intervals of 5 mA, multiple current intensities are set within the range from 5 mA to 200 mA to perform power-on treatment on the simulated contaminated soil in the electric domestication device 1 in sequence. And the cumulative treatment power-on time at each current intensity is 30 days. Then, within each 30-day range, the soil enzyme activity of the simulated contaminated soil and the plant physiological characteristic indexes of the functional plant 107 are detected at 10 days, 20 days, and 30 days respectively.

[0124] Step 3.6: Determine the functional microorganism window conditions according to the soil enzyme activities determined in Step 3.5, determine the functional plant window conditions according to the plant physiological characteristic indexes determined in Step 3.5, and then obtain the current-strengthened dual window conditions according to the functional microorganism window conditions and the functional plant window conditions.

[0125] In this embodiment, the "comprehensive biological activation index method" is used to determine the functional microorganism window conditions and the functional plant window conditions. Specifically:

[0126] Step 3.6.1: For the functional microorganism flora, measure the soil enzyme activities at different time points within the set number of days T. In this embodiment, within the 30-day power-on time range at each current intensity, obtain the activities of dehydrogenase, catalase, protease, urease, β-glucosidase, alkaline phosphatase, lipase, sucrase, peroxidase, and soil cellulase in the simulated contaminated soil samples at 10 days, 20 days, and 30 days respectively.

[0127] The measurement of the activities of the above soil enzymes are all well-known techniques in the art. Among them:

[0128] In this embodiment, the method for measuring soil dehydrogenase is as follows: Take 0.5 g of fresh soil and place it in a 50 ml colorimetric tube. Sequentially add 2 ml of Tris-HCl buffer solution, 1 ml of 0.1 mol / L glucose solution, and 1 ml of 0.5% TTC solution, shake evenly, and after centrifugation for 5 min, measure the toluene extract at 492 nm in a spectrophotometer. At the same time, set a control without soil and without TTC (substitute with distilled water), and perform quantitative analysis using a standard curve.

[0129] In this example, the method for determining soil catalase is as follows: Weigh 5 g of soil sample into a stoppered Erlenmeyer flask, add 0.5 mL of toluene, shake well, place it in a refrigerator at 4 °C for 30 min, take it out, immediately add 25 mL of 3% H2O2 aqueous solution stored in the refrigerator, mix well, and then place it in the refrigerator for 1 h. Take it out, quickly add 25 mL of 2 mol / L H2SO4 solution stored in the refrigerator, shake well, and filter. Take 1 mL of the filtrate into a triangular flask, add 5 mL of distilled water and 5 mL of 2 mol / L H2SO4 solution, and titrate with 0.02 mol / L potassium permanganate solution. According to the titration difference between the control and the sample, calculate the amount of KMnO4 consumed corresponding to the decomposed H2O2. The catalase activity is expressed as the volume of 0.1 mol / L KMnO4 consumed per gram of dry soil in 1 h (in mL).

[0130] In this example, the method for determining soil protease is as follows: The protease activity is determined by the ninhydrin colorimetric method. Weigh 4 g of air-dried soil, place it in a 50 ml Erlenmeyer flask, add 20 ml of 1% casein solution and 1 ml of toluene, carefully shake and cover it tightly with a cork, and incubate it in a constant temperature incubator at 30 °C for 24 h. After the incubation, add 2 ml of 10% NH2SO4 and 12 ml of 20% Na2SO4 solution to the mixture to precipitate proteins, centrifuge for 15 min, take 2 ml of the supernatant, place it in a 50 ml volumetric flask, and perform colorimetric determination according to the method of drawing the standard curve for color development.

[0131] In this example, the method for determining soil urease is as follows: Weigh 5 g of soil sample into a 50 ml Erlenmeyer flask, add 1 ml of toluene, shake well, after 15 min, add 10 ml of 10% urea solution and 20 ml of citrate buffer solution with a pH value of 6.7, shake well and incubate it in a constant temperature incubator at 37 °C for 24 h. After the incubation, filter, take 1 ml of the filtrate and add it to a 50 ml volumetric flask, then add 4 ml of phenol sodium solution and 3 ml of sodium hypochlorite solution, shake well immediately after adding, develop color after 20 min, make up the volume, and perform colorimetric determination at a wavelength of 578 nm on a spectrophotometer within 1 h.

[0132] In this example, the method for determining soil β-glucosidase is as follows: Take 1 g of fresh soil sample (less than 2 mm) into a 100 ml Erlenmeyer flask, add 0.25 ml of toluene, ventilate for 10 min, then add 4 ml of MUB solution with a pH value of 6.0 and 1 ml of PNPG solution, cover the bottle cap, mix well, and incubate at 37 °C for 1 h. Add 1 ml of CaCl2 solution and 4 ml of Tris buffer solution with a pH value of 12, shake well, quickly filter with a fast filter paper, and perform colorimetric determination on the filtrate under the condition of 400 nm.

[0133] In this example, the method for determining soil alkaline phosphatase is as follows: Weigh 5 g of fresh soil passed through a 2-mm sieve and place it in a 50-mL stoppered Erlenmeyer flask. Add 10 mL of 0.5 mol / L Tris-HCl buffer solution and 5 mL of 0.05 mol / L disodium phenyl phosphate solution. After shaking well, incubate in a constant temperature incubator at 37 °C for 24 h. After incubation, filter, pipette 1 mL of the filtrate into a 50-mL volumetric flask, add 4 mL of 0.3% 4-aminoantipyrine solution and 4 mL of 2.5% potassium ferricyanide solution, shake well, make up the volume to the mark with deionized water, and let it stand for 15 min. Then, at a wavelength of 510 nm, using the blank test (replacing the disodium phenyl phosphate solution with an equal volume of water and performing the same other operations) as a control, measure the absorbance with a spectrophotometer.

[0134] In this example, the method for determining soil lipase is as follows: Weigh 2 g of a properly sieved air-dried soil sample and place it in a stoppered test tube. Add a certain amount of p-nitrophenyl palmitate acetone solution and phosphate buffer solution. After shaking well, incubate in the dark with shaking at 37 °C for 1 h. After the incubation ends, add sodium carbonate solution to terminate the reaction, centrifuge or filter, and measure the absorbance of the supernatant at a wavelength of 405 nm. At the same time, draw a standard curve with a p-nitrophenol standard solution.

[0135] In this example, the method for determining soil invertase is as follows: Weigh 5 g of soil and place it in a 50-ml Erlenmeyer flask. Inject 15 ml of 8% sucrose solution, 5 ml of phosphate buffer solution with a pH value of 5.5, and 5 drops of toluene. After shaking the mixture well, place it in an incubator and incubate at 37 °C for 24 h. Take it out when the time is up and filter quickly. Pipette 1 ml of the filtrate therefrom into a 50-ml volumetric flask, add 3 ml of DNS reagent, and heat it in a boiling water bath for 5 min. Immediately transfer the volumetric flask to cool under running tap water for 3 min. The solution turns orange-yellow due to the formation of 3-amino-5-nitrosalicylic acid. Finally, dilute it to 50 ml with distilled water and perform colorimetry at 508 nm on a spectrophotometer.

[0136] In this example, the method for determining soil peroxidase is as follows: Weigh 5 g of fresh soil and place it in a 50-mL stoppered Erlenmeyer flask. Add 20 mL of phosphate buffer solution, 1 mL of 0.5% guaiacol solution, and 5 mL of 0.3% H2O2 solution. After shaking well, incubate in a constant temperature incubator at 37 °C for 1 h. After the incubation ends, immediately add 5 mL of 2 mol / L H2SO4 to terminate the reaction, then filter, and take the filtrate. At a wavelength of 460 nm, using the blank test (replacing the hydrogen peroxide solution with an equal volume of water) as a control, measure the absorbance with a spectrophotometer.

[0137] In this embodiment, the method for measuring soil cellulase is as follows: Weigh 10 g of soil and place it in a 50-ml Erlenmeyer flask. Add 1.5 ml of toluene, shake well, and let it stand for 15 min. Then add 5 ml of 1% carboxymethyl cellulose solution and 5 ml of acetate buffer with a pH value of 5.5. Place the Erlenmeyer flask in an incubator at 37°C for 72 h. After the incubation, filter and take 1 ml of the filtrate, and then perform colorimetric determination according to the standard curve color development method.

[0138] Step 3.6.2: For the functional plants, measure each plant physiological characteristic index at different time points within the set number of days T. In this embodiment, within the 30-day power-on time range at each of the above current intensities, obtain the plant physiological characteristic indexes at 10 days, 20 days, and 30 days, including measuring the plant height, root length, fresh weight of aboveground biomass, fresh weight of underground biomass, and chlorophyll content, where:

[0139] (1) The measurement of plant height, root length, fresh weight of aboveground biomass, and fresh weight of underground biomass is specifically as follows: Take the whole plant, measure the length of the aboveground part and the length of the underground part as the plant height and root length respectively. Then wash the aboveground and underground parts of the plant to remove surface impurities, place them in an oven at 105°C for 30 minutes for fixation, and then place them in an oven at 80°C until constant weight, and weigh after cooling.

[0140] (2) The measurement of the chlorophyll content of the plant is specifically as follows: Weigh a certain amount of plant leaves, wash, dry, and cut them into pieces, put them into a mortar, add an appropriate amount of 80% acetone, and grind them into a homogenate. Transfer the homogenate to a centrifuge tube, and take the supernatant after centrifugation. Pour the supernatant into a cuvette, use the extract as a blank control, and measure the absorbance values at specific wavelengths such as 645 nm and 663 nm (chlorophyll a has the maximum absorption at 663 nm, and chlorophyll b has the maximum absorption at 645 nm) with a spectrophotometer. Finally, calculate the contents of chlorophyll a, chlorophyll b, and total chlorophyll according to the following formulas:

[0141] Chlorophyll a content: C a (mg / L) = 12.7A 663 - 2.69A 645

[0142] Chlorophyll b content: C b (mg / L) = 22.9A 645 - 4.68A 663

[0143] Total chlorophyll content: C t (mg / L) = C a + C b = 8.02A 663 + 20.21A 645 。

[0144] Where A 663 is the absorbance value of chlorophyll a at 663 nm, and A 645 is the absorbance value of chlorophyll b at 645 nm.

[0145] Step 3.6.3: According to the various soil enzyme indexes obtained in Step 3.6.1, calculate the microbial single activation index of each soil enzyme index at each time node (i.e., the 10-day, 20-day, and 30-day time points within each 30-day range). According to the various plant physiological characteristic indexes obtained in Step 3.6.2, calculate the plant single activation index of each plant physiological characteristic index at each time node (i.e., the 10-day, 20-day, and 30-day time points within each 30-day range).

[0146] In this embodiment, the calculation processes of the microbial single activation index and the plant single activation index are the same, specifically:

[0147] Specify BAV i j represents the biological activity value of the i-th biological index at the j-th time node, and BAV i Ref represents the biological activity value of the i-th biological index at the initial time node (0 days) as the reference sample value, RBAV i j represents the relative biological activity value of the i-th biological index at the j-th time node, and is calculated according to the following formula:

[0148] RBAV i j =(BAV i j -BAV i Ref ) / BAV i Ref ;

[0149] Or

[0150] RBAV i j =(BAV i Ref -BAV i j ) / BAV i Ref ;

[0151] The RBAV obtained by calculation i j refers to the criterion and assignment method in Table 1 below, and further calculates the single activation index value

[0152]

[0153] Table 1

[0154] The parameters and methods in Table 1 above are variations based on the calculation and application direction of the "Microbial Stress Index (MSI)" (Wang et al., 2017), and the parameters are determined by combining practical experience. However, the index expressions and representative physical characteristics in the calculation method are different (for reference, see Meie Wang, Jack H. Faber b, Weiping Chen. Application of stress index in evaluating toxicological response of soil microbial community to contaminants in soils. 2017, Ecological Indicators 75 118–125.).

[0155] Step 3.6.4: According to the microbial single activation index of soil enzyme indicators at each time node, calculate the microbial comprehensive biological activation index by calculating the mean value, and the current intensity range formed by the current intensity corresponding to the maximum microbial comprehensive biological activation index and its adjacent minimum current intensity constitutes the functional microbial window condition. See Figure 3 and Figure 5 ;

[0156] According to the plant single activation index of plant physiological characteristic indicators at each time node, calculate the plant comprehensive biological activation index by calculating the mean value, and the current intensity range formed by the current intensity corresponding to the maximum plant comprehensive biological activation index and its adjacent minimum current intensity constitutes the functional plant window condition. See Figure 4 and Figure 5 .

[0157] In this embodiment, the calculation of the microbial comprehensive biological activation index and the plant comprehensive biological activation index is the same, and both are calculated according to the following formula:

[0158]

[0159] In the above formula, is the comprehensive biological activation index, n is the number of biological indices, and m is the number of time nodes.

[0160] In this embodiment, as shown in Figure 3 and Figure 5 , the current intensity range of the functional microbial window condition determined according to the change of the calculated microbial comprehensive biological activation index is 45 - 80 mA, as shown in Figure 4 and Figure 5As shown, the current intensity range of the functional plant window condition determined according to the calculated comprehensive biological activation index of the plant is 60 - 120 mA.

[0161] Step 3.6.5: Obtain the current-enhanced dual window condition according to the functional microorganism window condition and the functional plant window condition, specifically:

[0162] Define the functional microorganism window condition as WCM, the functional plant window condition as WCP, and the current-enhanced dual window condition as Dual-WC. Then the value range of Dual-WC is:

[0163] I. When Then there is:

[0164] Dual-WC ∈ [Dual-WC min , Dual-WC max = min(WCM, WCP);

[0165] II. When Then there is:

[0166] Dual-WC ∈ [Dual-WC min , Dual-WC max = WCM ∩ WCP;

[0167] Among them is an empty set, Dual-WC min , Dual-WC max are respectively the minimum value and the maximum value of Dual-WC, min(WCM, WCP) is the minimum value of WCM and WCP, and WCM ∩ WCP is the intersection of WCM and WCP.

[0168] As Figure 5 shown, in this embodiment, based on the functional microorganism window condition of 45 - 80 mA and the functional plant window condition of 60 - 120 mA, it meets the condition. Therefore, after taking the intersection, the current intensity range of the current-enhanced dual window condition K is 60 - 80 mA, that is, the effective current intensity range for simultaneously enhancing the functional microorganism flora and the functional plant is 60 - 80 mA.

[0169] Step Four: Construct the electrokinetic enhanced ecological reactor system 2, specifically:

[0170] Step 4.1: Inoculate the functional microorganism flora into the culture medium for cultivation, and then inoculate it into the actual contaminated soil. The microbial abundance of the actual contaminated soil after inoculation needs to reach the set value X3.

[0171] In this embodiment, after the functional microbial flora is fermented and cultured in a beef extract peptone liquid medium for 48 hours, the cells are collected by centrifugation and resuspended in an inorganic salt liquid medium. After resuspension, it is uniformly mixed into the actual PAHs-contaminated soil, and the microbial abundance in the actual contaminated soil needs to reach X3 = 8.9×10 8 CFU·g -1 .

[0172] Step 4.2: Stack and build the electric enhanced ecological stack system 2, as shown in Figures 6 - 10 . When stacking, first fill the medium stacking buffer layer 202, and arrange a buffer liquid supply pipe 204 horizontally in the buffer layer 202 and a longitudinal anode 205 vertically. Then, stack the actual contaminated soil obtained in Step 4.1 on the buffer layer 202 to form a stack body main body 201, and set retaining fiber nets on the side walls of the stack body main body 201 for fixation. A longitudinal cathode 206 is arranged vertically at the upper end of the stack body main body 201, and the longitudinal anode 205 and the longitudinal cathode 206 are respectively connected to a constant-direction power supply system 212 through a longitudinal anode wire 2051 and a longitudinal cathode wire 2061. After the longitudinal anode 205 and the longitudinal cathode 206 are energized, a longitudinal electric field is formed in the stack body main body 201. A first side wall electrode 207 is arranged on one side of the stack body main body 201, and a second side wall electrode 213 is arranged on the other side, and the polarities of the first side wall electrode 207 and the second side wall electrode 213 are opposite. The first side wall electrode 207 and the second side wall electrode 213 are respectively connected to an inverted-pole power supply system 208 through corresponding side wall electrode wires 214. The inverted-pole power supply system 208 supplies power to the first side wall electrode 207 and the second side wall electrode 213 by means of an inverted-pole method that changes the electrode polarity, and the first side wall electrode 207 and the second side wall electrode 213 form a transverse electric field in the stack body main body 201. In addition, a supply pipeline 209 is vertically arranged in the middle of the stack body main body 201 in the transverse direction, and a gas guide pipeline 203 is horizontally arranged in the middle in the height direction. In order to meet the supply needs of the functional microbial flora and moisture in the stack body main body 201 during the repair process, the supply pipeline 209 is connected to the inverted-pole power supply system 208 through a supply pipeline anode wire 211 and is not affected by the inverted-pole change of the inverted-pole power supply system 208. The supply pipeline 209 is always the anode. In this way, no matter how the polarities of the side wall electrodes on both sides change, one of the side wall electrodes will be the cathode and a transverse DC migration electric field will be formed between it and the supply pipeline 209. The constant-direction power supply system 212 and the inverted-pole power supply system 208 are both well-known technologies in the art and are commercially available products.

[0173] As shown in Figures 6 - 10 , in this embodiment, the filling medium in the buffer layer 202 is composed of conductive carbon black and clean soil mixed in a ratio of 1:8, and 0.05 mol·L is added at the same time-1 Industrial-grade phosphate buffer solution, the target value of the moisture content of the buffer layer 202 medium is 15% (V / W); the thickness of the buffer layer 202 is 8 cm.

[0174] As Figures 6 - 10 shown, in this embodiment, the side walls of the four directions of the heap body main body 201 form a 70° angle with the bottom, and a retaining fiber mesh with a grid density of 0.5 per cm is arranged on the surface of each side wall. 2

[0175] As Figures 6 - 10 shown, in this embodiment, the upper end of the supply pipeline 209 is connected to the supply storage tank 2091 through the supply connection pipeline 2092, and a supply pump 2093 is provided on the supply connection pipeline 2092. The lower end of the supply pipeline 209 is sealed, and supply holes 2094 are evenly distributed on the supply pipeline 209 for outputting the bacterial agent and moisture.

[0176] As Figures 6 - 10 shown, in this embodiment, the air guide pipeline 203 is respectively connected to the corresponding interfaces on an air guide multi-way joint 2033. The air guide multi-way joint 2033 is connected to the aeration pump 2031 through the air guide connection pipe 2032, and air holes 2034 are evenly distributed on the air guide pipeline 203. When the present invention works, the aeration pump 2031 aerates the soil in the heap body main body 201 through the air guide pipeline 203. The air guide multi-way joint 2033 is a commercially available product.

[0177] As Figures 6 - 10 shown, in this embodiment, the buffer solution supply pipe 204 is respectively connected to the corresponding interfaces on a buffer solution multi-way joint 2043. The buffer solution multi-way joint 2043 is connected to the buffer solution storage tank 2041 through the buffer solution connection pipe, and a buffer solution pump 2042 is provided on the buffer solution connection pipe. Buffer solution holes 2044 are evenly distributed on the buffer solution supply pipe 204. The buffer solution supply pipe 204 is used to supply 0.05 mol·L -1 industrial-grade phosphate buffer solution to the buffer layer 202 and control the moisture content of the buffer layer 202 medium within the range of 13% - 16% (V / W). The buffer solution multi-way joint 2043 is a commercially available product.

[0178] As Figures 6 - 10 shown, in this embodiment, a thermometer 210 is provided in the heap body main body 201 for real-time monitoring of the temperature inside the heap, and the thermometer 210 is connected to the reverse-polarity power supply system 208 through a circuit.

[0179] The volume of the heap body main body 201 and the quantities, dimensions and arrangement densities of the longitudinal anodes 205, longitudinal cathodes 206, gas conduction pipelines 203 and buffer solution supply pipes 204 are all set according to actual needs.

[0180] Step 4.3: After the electric enhanced ecological heap system 2 is built, functional plants are planted on the upper surface and each side wall of the heap body main body 201.

[0181] In this embodiment, ryegrass is planted on the upper surface and each side wall of the heap body main body 201, and the planting density is 30 ug·cm -2 .

[0182] Step Five: After the set number of days for the functional plants to germinate, the electric enhanced ecological heap system 2 starts the power-on repair treatment. The overall repair cycle of this embodiment is 60 days, and during the repair process, the current intensity, microbial abundance, soil water content in the soil of the heap body main body 201 and the soil pH value in the buffer layer 202 are measured respectively, where:

[0183] One, the longitudinal electric field and the transverse electric field operate alternately, and the current intensities of the longitudinal electric field and the transverse electric field are controlled within the current enhancement dual-window condition range. Among them, as the treatment continues, the longitudinal electric field and the transverse electric field will be lower than the lower limit value of the current enhancement dual-window condition determined in Step Three, as Figure 11 shown. In this embodiment, on the 13th, 23rd, 32nd, 39th, 47th, 51st and 56th days respectively, the current intensities of the longitudinal electric field and the transverse electric field are both lower than the lower limit value of 60 mA of the current enhancement dual-window condition. At this time, it is necessary to supply the inorganic salt solution through the supply pipeline 209, and stop the supply and continue the electric treatment when the current intensity reaches the upper limit value of 80 mA of the current enhancement dual-window condition.

[0184] In this embodiment, the alternating operation period of the longitudinal electric field and the transverse electric field is 12 hours. The longitudinal electric field is formed by the longitudinal anode 205 and the longitudinal cathode 206, and the power-on control is carried out through the constant-direction power supply system 212. The transverse electric field is formed by the first side wall electrode 207 and the second side wall electrode 213, and the power-on control and the pole-reversal change control are carried out through the pole-reversal power supply system 208. In this embodiment, the pole-reversal period is 0.5 hours. In addition, for the heap body main body 201, the present invention aerates the heap soil through the gas conduction pipeline 203. In this embodiment, ventilation is carried out once every 12 hours, and each aeration lasts for 10 minutes.

[0185] Two, as Figure 12As shown, in this embodiment, sensors are provided at positions 10 cm, 30 cm, 60 cm, and 90 cm from the bottom to the top of the heap body 201 to detect the soil water content, and the maximum difference in the soil water content at each location is only 3.6%. This indicates that the longitudinal electric field can effectively delay the downward transport of gravitational water in the heap soil, thereby maintaining a uniform distribution of soil moisture to a certain extent.

[0186] III. When the microbial abundance in the soil is reduced to a set value during the remediation process, functional microbial flora needs to be replenished through the supply pipeline 209 at this time. In this embodiment, as Figure 13 shown, the bacterial microbial abundance in the soil has been reduced to 7.76×10 5 CFU·g -1 after 36 days of continuous remediation. Therefore, functional microbial flora needs to be replenished through the supply pipeline 209 at this time. Immediately after replenishment, power is supplied to the supply pipeline 209 to activate the migration electric field. The supply pipeline 209 is connected to the bipolar power supply system 208 through the supply pipeline anode wire 211 and always serves as the anode. As the bipolar cycle changes, the supply pipeline 209 continuously forms a migration electric field with the cathodes in the sidewall electrodes on both sides to be responsible for evenly transporting the bacterial agent and moisture into the heap soil. Therefore, the operation time of the migration electric field is synchronized with the operation cycle of the transverse electric field. When the cumulative operation time of the migration electric field reaches 48 hours, the power supply to the supply pipeline 209 is disconnected, and at this time, the separate transverse electric field electrokinetic treatment is restored. After the replenishment of the functional microbial flora, the abundance of functional microorganisms in the heap soil can be maintained to meet the treatment requirements.

[0187] In addition, for the purpose of comparison, the electrokinetic enhanced ecological heap system 2 constructed by the present invention for remediation and disposal is labeled as EB-biopile, while the traditional microbial remediation treatment is used as a comparison and labeled as BIO. As Figure 13 shown, the bacterial microbial abundance of the electrokinetic enhanced ecological heap system 2 constructed by the present invention at each time node (EB-biopile) is higher than that of the traditional microbial remediation technology (BIO), which shows the maintaining effect of the electrokinetic enhanced ecological heap remediation technology provided by the present invention on the microbial abundance in the soil.

[0188] IV. During the remediation process of the present invention, the soil pH value of the heap body 201 will show a gradually acidifying trend. At this time, the buffer solution supply pipe 204 is activated to supplement the buffer solution into the soil to control the soil pH value of the heap body 201.

[0189] As Figure 14As shown in the figure, a pH detection sensor is provided at the lower end 10 cm of the heap body main body 201. During the repair process, the pH value of the soil at the lower end 10 cm of the heap body main body 201 shows a gradually acidifying trend. In particular, the changes in soil pH at the 18th day and the 42nd day of treatment are 1.1 and 0.8 pH units lower than those at the 0th day and the 24th day respectively. Therefore, in the lower buffer layer 202, industrial-grade phosphate buffer solution is supplied to the soil through the buffer solution supply pipe 204 at the 18th day and the 42nd day respectively, and the moisture content of the buffer layer 202 medium is controlled within the range of 13% - 16% (V / W). After the above regulation, the overall pH value of the soil of the heap body main body 201 remains above 6.3, and the physiological activity of the functional microbial flora is basically not interfered under this weakly acidic condition. -1 V. As shown in the figure, during the repair process, there are significant differences in the degradation effects of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) on PAHs with different ring numbers. Among them, for the degradation of phenanthrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 89.8% and 60.8% respectively; for the degradation of pyrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 53.8% and 29.8% respectively; and for the degradation of benzo[a]pyrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 32.1% and 9.5% respectively. In summary, it can be seen that the electrokinetic enhanced ecological heap system 2 of the component of the present invention shows significant advantages in the repair efficiency for PAHs with different ring numbers compared with the traditional microbial repair technology. Especially in the repair of soil polluted by high-ring PAHs, it has more application value. Therefore, the electrokinetic enhanced ecological heap repair technology provided by the present invention for the repair of organic polluted soil has good application effects and will have good potential for technology transformation and market application prospects in the future.

[0190] V. As Figure 15 shown, during the repair process, there are significant differences in the degradation effects of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) on PAHs with different ring numbers. Among them, for the degradation of phenanthrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 89.8% and 60.8% respectively; for the degradation of pyrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 53.8% and 29.8% respectively; and for the degradation of benzo[a]pyrene, the degradation rates of the treatment technology (EB-biopile) of the present invention and the traditional microbial treatment technology (BIO) are 32.1% and 9.5% respectively. In summary, it can be seen that the electrokinetic enhanced ecological heap system 2 of the component of the present invention shows significant advantages in the repair efficiency for PAHs with different ring numbers compared with the traditional microbial repair technology. Especially in the repair of soil polluted by high-ring PAHs, it has more application value. Therefore, the electrokinetic enhanced ecological heap repair technology provided by the present invention for the repair of organic polluted soil has good application effects and will have good potential for technology transformation and market application prospects in the future.

Claims

1. A method for electrokinetic enhanced remediation of organically contaminated soil, characterized in that: The steps include: Step 1: Determine the original functional microbial flora and functional plants suitable for electric field conditions according to the contaminated soil conditions; Step 2: domesticating the original functional microbial flora according to the functional plant conditions and obtaining the functional microbial flora; Step 3: Determine the current-enhanced dual window conditions for functional microbial flora and functional plants; Step 4: Construct an electric enhanced ecological pile system (2), specifically: Step 4.1: Inoculate the functional microbial flora into the culture medium for cultivation, and then inoculate it into the actual contaminated soil. The microbial abundance of the actual contaminated soil after inoculation is required to reach the set value X3; Step 4.2: stacking a buffer layer (202), and arranging a buffer supply pipe (204) in the buffer layer (202) along the horizontal direction, and arranging a longitudinal anode (205) along the vertical direction, and then stacking the actual contaminated soil obtained in step 4.1 on the buffer layer (202) to form a pile body (201), and arranging a longitudinal cathode (206) along the vertical direction at the upper end of the pile body (201), forming a longitudinal electric field between the longitudinal anode (205) and the longitudinal cathode (206), and arranging a first side wall electrode (207) on one side of the pile body (201) and a second side wall electrode (213) on the other side, and forming a transverse electric field between the first side wall electrode (207) and the second side wall electrode (213), and arranging a supply pipeline (209) vertically in the middle of the pile body (201) in the horizontal direction, and a gas guide pipeline (203) horizontally in the middle of the height direction; Step 4.3: Planting functional plants on the upper surface of the pile body (201) and on each side wall; Step 5: After the functional plants germinate for a set number of days, the electric enhanced ecological pile system (2) begins to perform power-on repair treatment, and during the repair process, the current intensity of the longitudinal electric field and the transverse electric field is controlled according to the current enhancement binary window conditions determined in step 3.

2. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 1, characterized in that: Step 2 is as follows: Step 2.1: Obtaining the original functional microbial flora; Step 2.2: The original functional microbial flora obtained in step 2.1 is inoculated into the simulated contaminated soil, and the microbial abundance of the simulated contaminated soil after inoculation is required to reach the set value X1; Step 2.3: The simulated contaminated soil obtained in step 2.2 is placed in an electric acclimation device (1), and functional plants are planted and then subjected to electric acclimation treatment. After acclimation, the rhizosphere soil of the functional plants is collected and processed to form a functional microbial flora.

3. The method for electrokinetic enhanced remediation of organic contaminated soil according to claim 2, characterized in that: In step 2.3, the electric taming device (1) comprises an anode electrode chamber (102), a taming chamber (101) and a cathode electrode chamber (103) which are arranged in sequence, and a conductive salt bridge joint (104) is provided between the anode electrode chamber (102) and the taming chamber (101) and between the cathode electrode chamber (103) and the taming chamber (101); Step 2.3 is as follows: Step 2.3.1: The anode electrode chamber (102) and the cathode electrode chamber (103) are both filled with real clean soil, and the simulated contaminated soil obtained in step 2.2 is placed in the acclimatization chamber (101), and then water is added to the clean soil and the simulated contaminated soil to reach saturated water content; Step 2.3.2: Planting functional plants in the acclimatization room (101) at a set density; Step 2.3.3: After the functional plant germinates for a set time, the acclimation anode (1021) is inserted into the anode electrode chamber (102), and the acclimation cathode (1031) is inserted into the cathode electrode chamber (103); Step 2.3.4: starting the constant current power supply system (105) to energize the taming anode (1021) and the taming cathode (1031), and using a circulating current method to perform taming treatment on the simulated contaminated soil in the taming chamber (101); The circulating current method is specifically as follows: within a set current intensity range, at a set current intensity interval, the current intensity is first gradually increased, then gradually decreased, and this cycle is repeated until the total cycle period reaches the set time; Step 2.3.5: Collect rhizosphere soil of functional plants; Step 2.3.6: The rhizosphere soil obtained in step 2.3.5 is processed to finally obtain the domesticated functional microbial flora.

4. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 1, characterized in that: Step three is as follows: Step 3.1: Inoculate the functional microbial flora into the culture medium for cultivation, and then inoculate it into the simulated contaminated soil. The microbial abundance of the simulated contaminated soil after inoculation is required to reach the set value X2; Step 3.2: Detection is performed using an electric acclimation device (1), wherein the electric acclimation device (1) comprises an anode electrode chamber (102), an acclimation chamber (101) and a cathode electrode chamber (103) which are arranged in sequence, and a conductive salt bridge joint (104) is provided between the anode electrode chamber (102) and the acclimation chamber (101) and between the cathode electrode chamber (103) and the acclimation chamber (101), wherein the simulated contaminated soil obtained in step 3.1 is placed in the acclimation chamber (101), and the anode electrode chamber (102) and the cathode electrode chamber (103) are respectively filled with real clean soil, and water is added to the clean soil and the simulated contaminated soil to reach saturated water content; Step 3.3: Planting functional plants in the acclimatization room (101) at a set density; Step 3.4: After the functional plant germinates for a set time, the acclimation anode (1021) is inserted into the anode electrode chamber (102), and the acclimation cathode (1031) is inserted into the cathode electrode chamber (103); Step 3.5: starting the constant current power supply system (105) to energize the domesticated anode (1021) and the domesticated cathode (1031), and sequentially performing power treatment on the simulated contaminated soil at a set number of current intensities, each current intensity is energized for a set number of days T, and within each set number of days T, soil enzyme activities in the rhizosphere soil of the functional plants and plant physiological characteristic indicators of the functional plants are detected at different time points; Step 3.6: Determine the functional microbial window conditions based on the soil enzyme activities determined in step 3.5, determine the functional plant window conditions based on the plant physiological characteristic indicators determined in step 3.5, and then obtain the current-enhanced dual window conditions based on the functional microbial window conditions and the functional plant window conditions.

5. The method for electrokinetic enhanced remediation of organic contaminated soil according to claim 4, characterized in that: Step 3.6 is as follows: Step 3.6.1: For the functional microbial flora, the activities of various soil enzymes at different time points are measured, including dehydrogenase, catalase, protease, urease, β-glucosidase, alkaline phosphatase, lipase, sucrase, peroxidase, and soil cellulase; Step 3.6.2: For functional plants, various plant physiological characteristic indicators at different time points are measured, including plant height, root length, aboveground biomass fresh weight, underground biomass fresh weight and chlorophyll content; Step 3.6.3: Based on the soil enzyme indicators obtained in step 3.6.1, calculate the microbial single activation index of each soil enzyme indicator at each time point; based on the plant physiological characteristic indicators obtained in step 3.6.2, calculate the plant single activation index of each plant physiological characteristic indicator at each time point; Step 3.6.4: According to the single microbial activation index of soil enzyme indicators at each time point, the microbial comprehensive biological activation index is obtained by calculating the mean, and the current intensity corresponding to the maximum microbial comprehensive biological activation index and the current intensity range formed by the minimum current intensity adjacent to it constitute the functional microbial window condition; According to the plant single activation index of plant physiological characteristic indicators at each time node, the plant comprehensive biological activation index is obtained by calculating the mean, and the current intensity range formed by the current intensity corresponding to the maximum plant comprehensive biological activation index and the minimum current intensity adjacent to it constitutes the functional plant window condition; The calculation of the microbial comprehensive bioactivation index and the plant comprehensive bioactivation index are the same, and are both calculated according to the following formula: In the above formula, is the comprehensive biological activation index, n is the number of biological indices, and m is the number of time nodes; Step 3.6.5: Obtain the current-enhanced dual window conditions based on the functional microbial window conditions and the functional plant window conditions, specifically: Define the functional microbial window condition as WCM, define the functional plant window condition as WCP, and define the current-enhanced dual-element window condition as Dual-WC. The value range of Dual-WC is:

1. When Then we have: Dual-WC∈[Dual-WC min ,Dual-WC max ]=min(WCM,WCP); 2. When Then we have: Dual-WC∈[Dual-WC min ,Dual-WC max ]=WCM∩WCP; in is an empty set, Dual-WC min 、Dual-WC max are the minimum and maximum values ​​of Dual-WC respectively, min(WCM, WCP) is the minimum value between WCM and WCP, and WCM∩WCP is the intersection of WCM and WCP.

6. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 5, characterized in that: In step 3.6.3, the calculation process of the microbial single activation index and the plant single activation index is the same, specifically: Specifying BAV i j represents the biological activity value of the i-th biological index at the j-th time node, BAV i Ref Represents the biological activity value of the i-th biological index at the initial time node as the reference sample value, RBAV i j Represents the relative biological activity value of the i-th biological index at the j-th time point, calculated according to the following formula: RBAV i j =(FATHER i j -FATHER i Ref ) / FATHER i Ref ; or RBAV i j =(FATHER i Ref -FATHER i j ) / FATHER i Ref ; RBAV obtained by calculation i j Refer to the criteria and assignment method in the table below to further calculate the single activation index value SBAI i j .

7. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 1, characterized in that: In step 4.2, the longitudinal anode (205) and the longitudinal cathode (206) are respectively connected to a constant power supply system (212) through corresponding wires; the first side wall electrode (207) and the second side wall electrode (213) have opposite polarities and are respectively connected to a reverse power supply system (208) through corresponding wires, the supply pipeline (209) is connected to the reverse power supply system (208) through the supply pipeline anode wire (211), and the supply pipeline (209) is always the anode.

8. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 7, characterized in that: In step five, the longitudinal electric field and the transverse electric field operate alternately, and when the current intensity of the longitudinal electric field and the transverse electric field is lower than the lower limit value of the current enhancement binary window condition, the supply pipeline (209) starts to supply the inorganic salt solution until the current intensity of the longitudinal electric field and the transverse electric field reaches the upper limit value of the current enhancement binary window condition, and the supply pipeline (209) stops supplying.

9. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 7, characterized in that: In step five, when the abundance of microorganisms in the soil of the main body of the pile (201) decreases to a set value, the supply pipeline (209) starts to supply the functional microbial flora, and after the supply, the inverted power supply system (208) supplies power to the supply pipeline (209) to make the supply pipeline (209) an anode. After the power supply reaches a set time, the inverted power supply system (208) disconnects the power supply to the supply pipeline (209); when the pH value of the soil of the main body of the pile (201) decreases, the buffer supply pipe (204) starts to supply buffer.

10. The method for enhanced electrokinetic remediation of organic contaminated soil according to claim 7, characterized in that: In step 4.2: The filling medium in the buffer layer (202) is a mixture of conductive carbon black and clean soil in a set ratio, and a set amount of buffer solution is added at the same time; Each side wall of the stack body (201) forms an angle of 70° with the bottom, and the grid density on the surface of each side wall is 0.5 / cm 2 Earth retaining fiber mesh; The upper end of the supply pipeline (209) is connected to the supply tank (2091) through a supply connecting pipeline (2092), and a supply pump (2093) is provided on the supply connecting pipeline (2092). The lower end of the supply pipeline (209) is sealed, and supply holes (2094) are evenly distributed on the supply pipeline (209); The air guide pipelines (203) are respectively connected to corresponding interfaces on an air guide multi-way connector (2033); the air guide multi-way connector (2033) is connected to an aeration pump (2031) via an air guide connecting pipe (2032); and aeration holes (2034) are evenly distributed on the air guide pipelines (203); The buffer supply pipe (204) is respectively connected to a corresponding interface on a buffer multi-way connector (2043), the buffer multi-way connector (2043) is connected to a buffer storage tank (2041) via a buffer connecting pipe, and a buffer pump (2042) is provided on the buffer connecting pipe, and buffer holes (2044) are evenly distributed on the buffer supply pipe (204); A thermometer (210) is provided in the stack body (201).

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