CN111346913A - Plant-microorganism comprehensive remediation system for polluted soil and underground water - Google Patents

Abstract

The invention provides a plant-microorganism comprehensive restoration of polluted soil and groundwater system, and mainly relates to the technical field of environmental restoration. A plant-microorganism integrated remediation system for polluted soil and groundwater, including an upstream injection well, a downstream pumping well, a polylactide restriction layer, a diaphragm pump, a nutrient injection well, an oxygen injection well, a nutrient and microbial filling area, and a water barrier Floor. The beneficial effects of the present invention are: according to the distribution of soil and groundwater pollution, the present invention can force the root system of plants to penetrate deep into the soil and groundwater of the polluted area, and at the same time combine the action of microorganisms to improve the efficiency of degradation, migration and transformation of pollutants in the rhizosphere microdomain, Combined with groundwater extraction-reinjection, it not only enhances groundwater circulation efficiency, increases the contact probability of pollutants in soil and groundwater with plant roots and microorganisms, but also increases groundwater aeration and accelerates the degradation of organic pollution.

Description

A plant-microbe integrated remediation of polluted soil and groundwater system

technical field

The invention mainly relates to environmental restoration technology, in particular to a plant-microbe comprehensive restoration of polluted soil and groundwater system.

Background technique

With the growth of my country's population, the acceleration of industrialization development and the improvement of per capita living standards, a large number of industrial and agricultural production and domestic pollutants enter the soil and groundwater, posing a great threat to ecological security and human health. The "National Soil Pollution Survey Bulletin" released in 2014 and the exposure of many pollution incidents in recent years have shown that the problem of soil and groundwater pollution in my country has become increasingly prominent, and the restoration of contaminated soil and groundwater is urgent.

Soil and groundwater remediation methods can be fundamentally divided into three categories: physical remediation, chemical remediation, and bioremediation. Different methods have their own advantages and disadvantages. At present, the remediation of pollutants is moving towards green, environment-friendly bioremediation and The development of technologies such as comprehensive repair of multiple combined hybridization. For example, the invention patent application with the application publication number CN102463253A discloses a plant-microbe joint restoration system for soil and shallow groundwater organic pollutants, and the invention patent application with the application publication number CN108706820A discloses a composite soil and groundwater circulation treatment device. The invention patent application with publication number CN104801536A discloses a method for remediating halogenated hydrocarbon contaminated sites by combining chemical leaching and microorganisms, and the invention patent application with publication number CN104692531A discloses a groundwater heavy metal pollution restoration device.

The above remediation systems and methods are only suitable for remediation of shallow groundwater or slow groundwater circulation, and the remediation efficiency is not high; the method of extracting the surface for treatment and then reinjecting it cannot change the tailing effect of the extraction process, and the applicable pollutant types are relatively small. Single, can not solve the problem of soil and groundwater pollution in my country.

SUMMARY OF THE INVENTION

In order to solve the deficiencies of the prior art, the present invention provides a plant-microbe comprehensive remediation system for polluted soil and groundwater. The present invention can force the root system of plants to penetrate deep into the soil and groundwater in the polluted area according to the distribution of soil and groundwater pollution. The role of microorganisms can improve the efficiency of degradation, migration and transformation of pollutants in the rhizosphere micro-domain, and combined with groundwater extraction-reinjection, it not only enhances the efficiency of groundwater circulation, but also improves the contact probability of pollutants in soil and groundwater with plant roots and microorganisms. Increase groundwater aeration to accelerate the degradation of organic pollution.

The present invention is achieved by the following technical solutions in order to achieve the above object:

A plant-microbe comprehensive remediation system for polluted soil and groundwater, comprising an upstream water injection well, a downstream pumping well, a diaphragm pump, and a water barrier, and a nutrient and microbial filling area is provided at the lower end of the downstream pumping well, and the nutrient and The filling area is located at the groundwater level ± 0.5m, and does not penetrate the aquifer. The downstream pumping well is surrounded by a polylactide restriction layer, a nutrient injection well and an oxygen injection well. The nutrient injection well is provided with injection holes, Screen holes are provided below the oxygen injection well.

As mentioned above, in the nutrient and microorganism filling area, the actinomycetes Streptomyces triceps Act12 and biochar are used as filling materials.

As mentioned above, plants are grown in the downstream pumping well.

As mentioned above, the plant is birch.

As mentioned above, there are 3-4 layers of gauze on the periphery of the mesh.

As mentioned above, plant plants as densely as possible in contaminated areas without affecting their normal growth.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention utilizes plant-microbe in situ joint restoration of polluted soil and groundwater, and the microorganisms in the rhizosphere micro-domain can improve root vitality and root tolerance to pollutant stress, and promote plant growth. The secretions, etc., promote the growth and reproduction of microorganisms, and the two complement each other, which can give full play to the functional advantages of plants and microorganisms, and improve the remediation efficiency of polluted soil and groundwater. The system has low cost, good effect, green, clean and no secondary pollution;

(2) During the growth process of plants and microorganisms, nutrients and oxygen are provided to plants and microorganisms through nutrient injection wells and oxygen injection wells, so as to promote the rapid growth of plants and the rapid reproduction of microorganisms, and effectively improve the repair efficiency;

(3) A polylactide restriction layer is used around the plant root system, which drives the plant root system to grow to the deep polluted area, which can meet the needs of deep soil and groundwater pollution remediation. Moreover, the system adopts the in-situ repair method, which avoids the tailing effect caused by the residual pollutants caused by the simple extraction-processing technology.

(4) Set up a downstream pumping well at the root of the plant, through the diaphragm pump, the downstream polluted groundwater is extracted to the upstream injection well, and the groundwater flow is used to bring the pollutants in the soil and groundwater to the plant root system, which can improve soil and groundwater. The contact probability of pollutants with plant roots and microorganisms is increased, groundwater aeration is increased, the degradation of organic pollution is accelerated, and pollution plumes are prevented from spreading downstream, so as to realize the coordinated restoration of vadose-contaminated soil, saturated-contaminated soil and groundwater.

Description of drawings

Accompanying drawing 1 is the structural representation of the present invention;

Accompanying drawing 2 is the structural schematic diagram of nutrient injection well and oxygen injection well;

Numerals shown in the drawings: 1, leaves; 2, upstream water injection well; 3, downstream pumping well; 4, polylactide restriction layer; 5, diaphragm pump; 6, nutrient injection well; 7, oxygen injection well; 8. Nutrient and microbial filling area; 9. Uncontaminated soil; 10. Contaminated soil and groundwater; 11. Groundwater flow direction; 12. Water barrier; 13. Tree root; 14. Injection hole;

Detailed ways

The present invention will be further described with reference to the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the present application.

As shown in Figures 1-2, a plant-microorganism comprehensive remediation system for polluted soil and groundwater according to the present invention includes an upstream injection well 2, a downstream pumping well 3, a diaphragm pump 5, an aquifer 12, and the downstream pumping well 3. The lower end is provided with a nutrient and microbial filling area 8, and the nutrient and microbial filling area 8 is located at the groundwater level ± 0.5m, and does not penetrate the water barrier 12, and the downstream pumping well 3 is provided with polylactide restrictions around it Layer 4, nutrient injection well 6 and oxygen injection well 7, the top of the polylactide confinement layer 4 is flush with the ground, the polylactide confinement layer 4 has the functions of anti-corrosion and anti-seepage, and can restrict the roots of plants The growth of the plant root system drives the growth of the plant root system to the polluted area, the injection hole 14 is provided on the nutrient injection well 6, and the sieve hole 15 is provided under the oxygen injection well 7, and the sieve hole 15 is convenient for oxygen to penetrate into the plant root system. After the capacity, the diaphragm pump 5 is used to extract the downstream polluted groundwater into the upstream water injection well 2, and through the groundwater flow, the pollutants in the polluted soil and groundwater are brought to the plant root system.

Specifically, the nutrient and microorganism filling area 8 uses actinomycetes Streptomyces triceps Act12 and biochar as filling materials. Act12 is a broad-spectrum growth-promoting bacteria that can stimulate plant root development and nutrient absorption, adjust the soil micro-ecological balance of plant roots, inhibit the growth of harmful microorganisms, promote the reproduction of beneficial microorganisms, improve microbial flora, and improve root vitality. and root tolerance to pollutant stress, increase the treatment load; optimize the root environment, promote the development of plant roots, and enhance the ability of phytoremediation to treat heavy metal-contaminated soil.

Specifically, plants are grown in the downstream pumping well 3 . Plants can remediate pollutants in soil and groundwater through plant extraction, volatilization, filtration, degradation, etc. At the same time, the huge surface area of plant roots can provide a host for microorganisms, and the oxygen transported by plants to the roots and the released root secretions, It can make corresponding changes in soil nutrients, enzyme activity and humidity in the rhizosphere micro-domain, thereby promoting the growth and activity of microorganisms.

Specifically, the plant is birch. Birch has a great potential to absorb heavy metals (such as zinc, cadmium, lead, nickel, arsenic, chromium, mercury, selenium and copper, etc.), and can repair organically polluted soil, and can also generate a large amount of wood or biomass energy.

Specifically, the sieve hole 15 is provided with 3-4 layers of gauze on the periphery. The gauze can effectively prevent soil particles from clogging the screen holes.

Specifically, under the premise of not affecting the normal growth of plants, plants are planted as densely as possible in the polluted area.

Example:

Using birch as the restoration plant, the following experiments were carried out.

A remediation system for jointly remediating polluted groundwater with plants and microorganisms specifically includes the following steps:

S1: Taking the pollution source as the center, investigate the type, concentration, pollution depth and groundwater flow direction of the pollutants in the groundwater;

S2: Select a pollution point with a groundwater pollution depth of 10-15m, and use the large-diameter auger technology to excavate a well with a diameter of 1m and a depth of ±0.5m from the groundwater level of the pollution point;

S3: Use the horizontal drilling process to excavate a channel in the polluted area, and place the nutrients and microorganisms (Streptomyces triceps Act12 and biochar) required for plant growth in the channel to form a filling area with nutrients and microorganisms;

S4: Set a polylactide restriction layer around the well, close to the inside of the well, the top is flush with the ground, and set up nutrient injection wells and oxygen injection wells around the well.

S5: Plant birch trees over 3 years old in the well, and plant birch trees in the polluted area in the above manner, with a tree length of 10m;

S6: In the early stage after the birch is transplanted, water the rhizosphere once a week, and inject nutrients and oxygen through the nutrient injection well and oxygen injection well once a month until the birch can grow normally;

S7: Set up a downstream pumping well at the root of the plant, and set up a diaphragm pump and an upstream water injection well in the upstream, so that the diaphragm pump is used to pump the downstream contaminated groundwater to the upstream injection well, and the groundwater flow direction is used to lead the downstream groundwater to the plant roots, and use the plant - Microbial integrated remediation system to remediate soil and groundwater.

S8: Detect the pollutant content in each tissue and the concentration of each pollutant in the groundwater, thereby judging the restoration of birch trees.

Every three months, the groundwater is extracted with an extraction pump in the groundwater polluted area for regular testing. The test data shows that in the fourth year after the birch is planted, the concentration of groundwater pollutants has reached the "Groundwater Quality Standard (GB/T14848-2017"). ) "Class IV water standard (as shown in Table 1). At this time, the roots, stems and leaves of birch trees planted for four years were taken for microwave digestion, and the pollutant content in each tissue and organ was determined by ICP-AES method. The results are shown in Table 2 and Table 3.

Table 1 Concentration of groundwater pollutants (before restoration)

Table 1

Table 2 Concentration of groundwater pollutants (after restoration)

Table 2

Table 3 The concentration of each organ of birch (after repair)

table 3

It can be seen from the above results that birch has a good remediation effect on heavy metals and organic matter in groundwater, and the accumulation amount in each organ is different. Plants remediate polluted groundwater mainly through plant root filtration, plant volatilization, rhizosphere degradation, and synergy with rhizosphere microorganisms.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: it can still be Modifications are made to the technical solutions described in the foregoing embodiments, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (6)

1. A plant-microbial comprehensive remediation system for polluted soil and groundwater, comprising an upstream water injection well (2), a downstream pumping well (3), a diaphragm pump (5), and an aquifer 12, characterized in that: the downstream pumping well (3) There is a nutrient and microorganism filling area (8) at the lower end, the nutrient and microorganism filling area (8) is located at the groundwater level ± 0.5m, and does not penetrate the aquifer (12), the downstream pumping well (3) A polylactide confinement layer (4), a nutrient injection well (6) and an oxygen injection well (7) are arranged around the nutrient injection well (6), and an injection hole (14) is provided on the nutrient injection well (6). A screen hole (15) is set under the injection well (7). 2. A plant-microorganism comprehensive remediation system for polluted soil and groundwater according to claim 1, characterized in that: the nutrient and microorganism filling area (8) adopts actinomycetes Streptomyces triceps Act12 and biochar as filling material. 3 . The plant-microbe comprehensive remediation system for polluted soil and groundwater according to claim 1 , wherein plants are grown in the downstream pumping well ( 3 ). 4 . 4. A plant-microorganism comprehensive remediation system for polluted soil and groundwater according to claim 3, wherein the plant is birch. 5 . The plant-microorganism comprehensive remediation system for polluted soil and groundwater according to claim 1 , wherein the sieve holes ( 15 ) are provided with 3-4 layers of gauze on the periphery. 6 . 6 . The plant-microbe comprehensive restoration of polluted soil and groundwater system according to claim 1 , wherein plants are planted as densely as possible in the polluted area without affecting the normal growth of plants. 7 .

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