KR100451018B1 - Multi-staged phyto-reactive barrier and purification method of multi-components contaminated groundwater using the same - Google Patents

Abstract

PURPOSE: To provide a multi-staged phyto-reactive barrier capable of purifying ground water that is contaminated by various materials and a method for purifying the contaminated ground water by using the multi-staged phyto-reactive barrier, which is able to provide maximum purification efficiency with a minimum cost. CONSTITUTION: The phyto-reactive barrier comprises a first reactive barrier (1) where herbaceous purifying plants (11) are planted, a second reactive barrier (2) where woody purifying plants (21) are planted, a third reactive barrier (3) that includes an adsorption medium and a fourth reactive barrier (4) where the woody purifying plants are planted.

Description

MULTI-STAGED PHYTO-REACTIVE BARRIER AND PURIFICATION METHOD OF MULTI-COMPONENTS CONTAMINATED GROUNDWATER USING THE SAME}

The present invention relates to a multi-stage plant reaction wall and a groundwater purification method using the same. More specifically, the present invention includes a primary reaction wall in which a herbaceous plant is planted, a secondary reaction wall in which a tree plant is planted, and an adsorption medium. It is a multi-stage plant reaction wall that includes a third reaction wall and a fourth reaction wall in which wood-purified plants are planted. By using this, the ground water contaminated with organic matter, heavy metals, and nutrients (nitrogen or phosphorus) is purified. In this case, the maximum purification efficiency can be obtained at the minimum cost.

Currently, groundwater is recognized as a very important land resource as a substitute for surface water. However, groundwater contamination is accelerating as various pollutants flow into the ground due to poor landfill or pollution leakage of hazardous wastes generated during industrial activities. As a result, it is difficult to use groundwater as a healthy water resource. Once pollutants enter the groundwater due to the presence of pollutants in the soil, groundwater contamination of a wide range occurs due to the flow of groundwater and the spread of the pollutants, and the treatment costs for the purification of the contaminated groundwater are astronomical. Therefore, there is an urgent need to secure an economical and efficient purification technology for groundwater contaminated with various materials.

In the art as a method for the purification of groundwater, various various processes are introduced according to the pollution characteristics. First, there is an air sparging method of installing a pipe into groundwater and injecting air, thereby degassing and releasing it to the atmosphere or adsorbing activated carbon. However, the above method requires enormous cost and energy, and sometimes has no problem at all.

Another method for the purification of groundwater is a physicochemical treatment method. However, the above method is suitable for treating highly contaminated groundwater, but its facilities and operation and maintenance costs are very expensive to treat the entire groundwater pool. There is. In addition, there is a problem that secondary pollutants are produced, or secondary treatment of exhaust gas treatment and treatment by-products such as waste activated carbon is required.

Another method for groundwater purification is a biological restoration method. In general, the biological restoration method can treat various contaminants by activating microorganisms in the soil and is relatively inexpensive, but has a problem in that the treatment speed is slow and the treatment efficiency varies greatly depending on various environmental variables. In particular, when groundwater is complexly contaminated with organic compounds and nitrates as in Korea, the pollutants cannot be treated at the same time, and a separate carbon source must be injected for the growth of nitrate bacteria for the treatment of nitrates. In addition, the contamination of the injection well and monitoring well often occurs and requires special maintenance there is a problem that the treatment cost increases.

Permeable Reactive Barriers (PRBs) are materials that are reactive with groundwater containing pollutants by installing a reactive medium similar to the soil in a direction perpendicular to the flow of groundwater in the soil. Contaminants are reacted and treated during the passage, and the reactants include metal iron (Fe ⁰ ), dithionite, zeolite, peat, bentonite, ORC, and chitosan. Beads (chitosan beads) and limestone (limestone) are widely used, and the groundwater is collected and treated in the form of impermeable walls (funnels) and hydrological (funnel and gate systems) to increase the efficiency of groundwater treatment. It is also widely used. The technique can be a breakthrough treatment technique under conditions where in-situ treatment is preferred, such as groundwater, in that energy input is unnecessary and the process is simple. However, as the contaminant load persists, the reactivity of the reactants is markedly reduced due to the accumulation of contaminants and the surface activity is reduced, and the permeability of the reaction walls is reduced, and the retention time is reduced by causing the channeling phenomenon. There is a problem that processing occurs.

In relation to Phytoremediation, inorganic pollutants such as heavy metals are known to be mainly absorbed and decomposed directly by plants, or the contaminants are concentrated in plants and volatilized through leaves. In this case, the increase of cometabolism through the activation of the root microorganism by the secretion of roots of low molecular weight organic acids and the supply of oxygen to the roots due to the difference in concentration between the plant body and the external environment, the mycorrhizal on the root interface. Mechanisms such as fungi) and mineralization of organic matter through the activity of mixed microbial groups are known. Flora restoration technology, which has been widely applied to the water purification of polluted groundwater, leachate, and wastewater from developed countries such as the US, Germany and the Netherlands since the 1990s, mainly focuses on the selection of suitable plant species. We are trying to find suitable cleansing plants for plants that are large, biomass-rich, and have high absorption capacity and resistance to external toxicity. Therefore, the above technology mainly regards the selection of new purified plants as the core of the technology. Species that accumulate metals high in the body include Indian Mustard ( Brassica juncea ), Pea ( Pisum sativum L.), Sunflower ( Helianthus annuus L.), Meadow foxtail ( Alopecurus pratensis L.), and Common timothy ( Phleum pratense L.) In Korea, horseshoe, gomari, mugwort, evening primrose and silver grass are known to be excellent in the absorption capacity of heavy metals and the ability to move to the ground.

The purification technology using the above plant is the most economical and nature-friendly technology because it bears only the cost of injecting light energy and the minimum nutrients required for plant growth, while the processing period is long and the plant growth is restricted by the overload of contaminants. Has problems such as; Therefore, there is a need for an alternative technique to overcome this limitation.

As described above, it is difficult to effectively remove various contaminants in the groundwater frequently generated by methods known in the art at the same time, and even at the same time, the cost is very high and the economy is inferior. Therefore, there is an urgent need to introduce a new concept that is economical and efficient, which can treat pollutants while protecting ground water, which is a future source of drinking water, and using a new concept that is not difficult to maintain and install.

An object of the present invention is to provide a multi-stage plant reaction wall capable of purifying complex contaminated ground water by various materials.

In another aspect, the present invention provides a method for the purification of complex contaminated groundwater using a multi-stage plant reaction wall that can obtain the maximum purification efficiency at a minimum cost in the field treatment of large-scale groundwater complex contaminated with organics and heavy metals. The purpose.

1 is an overall schematic diagram of a multistage plant reaction wall consisting of four stages in accordance with the present invention.

* Description of the main parts of the drawings

1. First Reaction Wall 11. Herbal Purification Plant

2. Second Reaction Wall 12. Woody Plant Purification Plant

3. Tertiary Reaction Wall 21. Contaminated Groundwater

4. Fourth Reaction Wall 22. Purified Groundwater

5. Groundwater level 23. Air

7. Air injection pipe 24. Air pump

8. Through hole 25. Extraction pump

9. Monitoring well

The multi-stage vegetative reaction wall of the present invention is a primary reaction wall in which the herbaceous plant is planted, a secondary reaction wall in which the tree plant is planted, a tertiary reaction wall including the adsorption medium, and a tree plant purification plant. Characterized in that it comprises a differential reaction wall.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is an overall schematic diagram of a multistage plant reaction wall consisting of four stages in accordance with the present invention.

In FIG. 1, the first reaction wall 1 has a perennial herbaceous plant 11 having a root depth of about 1 m and a radial root distribution, which is planted at regular intervals in a transverse direction with respect to the flow direction of the contaminated groundwater 21. The line consists of multiple columns. The planting form of the herbaceous plant purification plant 11 in the primary reaction wall 1 may be a plant perennial or a variety of seasonal plantings.

The primary reaction wall (1) prevents or reduces the loss of contaminated soil and the movement of dissolved contaminants by surface run-off, such as rainfall, biosorption and root absorption by plant root zone microorganisms. It removes and stabilizes contaminants. In other words, by filtering and sedimenting the fine soil containing dissolved pollutants and pollutants moving with the rainfall from the surface, it is responsible for preventing the spread of ground pollution and blocking the inflow into the groundwater layer.

The herbaceous purifying plant (11) planted in the primary reaction wall (1) is a perennial paper with fine roots can be well developed in the soil, high accumulation of organic and inorganic ions in vivo, and a broad surface area of the leaf Preferably, sunflower, horsetail, gomari, mugwort, evening primrose, silver grass, parrot hair, aquatic horsefly, laver, rye, reed and alfalfa are more preferable, and one or two or more of these plants can be selected. Herbal purification plants can be applied by the choice of those skilled in the art depending on the site conditions and contaminants.

In Figure 1, the secondary reaction wall (2) is a fast-growing woody plant purification plant (12) having a root depth of up to 4-5 m and a growth capacity within 1 to 2 years, the groundwater as the planting method of the herbaceous plant purification plant The plant reaction layer which consists of a plurality of the heat | fever planted at the predetermined interval horizontally with respect to a flow direction is provided. In addition, through the air pump 24 installed on the ground, the external air 23 is uniformly supplied to the underground root zone (root zone) and the contaminated groundwater layer at a constant flow rate, so that the aerobic conditions can be maintained in these areas. It is preferable to include a plurality of air inlet pipes 7 embedded in the contaminated groundwater zone at regular intervals. As the woody plant purification plant 12 in the secondary reaction wall 2, it is preferable to select one species of perennial woody plant for sufficient root expansion, and herbaceous plants and mixed plants are also possible. In addition, the air inlet tube 7 is preferably made of PVC or stainless steel, and a plurality of air permeable holes 8 are provided in the inlet tube part (in the underground part of the inlet tube part) located in the underground air injection section for effective air dispersion. It is preferable to install).

The secondary reaction wall 2 serves to pump the contaminated groundwater by the capillary effect by approaching the root of the woody plant 12 to the vicinity of the groundwater layer and phytofiltration the dissolved contaminants. In addition, by the aeration effect through the air inlet pipe 7 from the ground by the oxidative activity activation of the root zone microorganisms and direct oxidation by dissolved oxygen to reduce the toxicity and increase the adsorption performance by increasing the oxidation number of heavy metals such as arsenic, It also functions to promote biological decomposition of organic contaminants and nitrification of ammonia ions.

The woody plant purification plant 12 planted in the secondary reaction wall 2 has a wide native distribution regardless of the area, and the growth rate is fast and myocardial, so that the roots can be extended to the groundwater surface. It can be widened, and the amount of transpiration is large, so it is effective for groundwater treatment, and the water pipe is narrow, so that it can be milled, and a perennial species that can be applied to a wide area is preferable, and hybrid poplar, willow, rapeseed and aspen are more preferable. Wood-purified plants can be applied by the person skilled in the art according to the site conditions and contaminants.

The tertiary reaction wall 3 functions to filter most heavy metal ions or inorganic ions. In the form of the tertiary reaction wall (3), a trench having a predetermined width is installed up to the contaminated groundwater zone, and about 1 m of the topsoil layer is filled with bentonite-based material having an impermeable microparticle diameter to prevent the inflow of pollutants from the ground. Block 3-1, and the lower part is preferably filled with a permeable reactant to the contaminated groundwater layer (3-2) that can be removed through the reaction with the contaminants in the groundwater. Here, the depth of the trench can be selectively determined according to the depth of the contaminated groundwater basin, and a depth of 5 to 20 m is generally preferable. The trench installed in the tertiary reaction wall 3 is preferably provided with grouting to have long-term durability in the basement, and the reactant filled therein can be selected from a single or a plurality of materials depending on the contaminant phase.

The tertiary reaction wall 3 is filled with a reactant having excellent adsorption performance so that an effective adsorption and removal of inorganic oxide ions having improved adsorption performance in the secondary reaction wall 2 can be achieved. The reactants have sufficient particle permeability and pore size to ensure smooth water passage through sufficient water permeability, sufficient reaction specific surface area, robustness to maintain stable structure even in long-term application, and harmful effects on plant growth and surrounding environment Forms having non-toxic material properties not exhibiting are preferred, and metal iron (Fe ⁰ ), zeolite, pit, bentonite, ORC and chitosan beads are particularly preferred. The reactants may be selectively applied according to the choice of those skilled in the art according to the type and characteristics of the pollutant.

In the fourth reaction wall (4) is a section in which the tree main plant 12 is planted in the same manner as in the second reaction wall (2), the tree root purification plant 12 having a large root depth is planted anaerobic (anaerobic) By maintaining the conditions, the biochemical reduction reaction enables conversion of toxic heavy metals to oxidation water, denitrification of nutrients such as nitrates, and detoxification of chlorine-based compounds such as TCE or PCE or nitro-based organic compounds such as TNT. It is. That is, the groundwater passing through the tertiary reaction wall 3 finally removes residual contaminants by root filtration and at the same time plays a role of decomposing by biochemical reaction under anaerobic conditions. Here, a system including a groundwater monitoring well (9) and a groundwater extraction pump (25) installed at a predetermined interval by differentially laying underground depth to the groundwater layer at the rear end of the planting layer of the fourth reaction wall (4) In addition, it is preferable to observe the quality of the groundwater finally passed through the multi-stage vegetation reaction wall by depth in real time. The woody plant purification plant in the fourth reaction wall is preferably selected from one species of perennial woody plant purification plant for sufficient root expansion, it is also possible to mix planting with herbaceous plant purification plants.

In the quaternary reaction wall (4), the woody plant purification plant (12) has a wide native distribution regardless of the area, and the growth rate is fast and myocardial, so that the roots can be extended to the groundwater surface, thereby increasing the scale of treatment. In addition, a large amount of transpiration is effective for groundwater treatment, and the perennial species that can be applied to a wide area because of narrow water pipes are preferable, and hybrid poplar, willow, rapeseed and aspen are particularly preferable. Wood-purified plants can be applied by the person skilled in the art according to the site conditions and contaminants.

The scale of the multi-stage vegetative reaction wall of the present invention may be varied by the choice of a person skilled in the art according to the properties of the contaminated groundwater. Preferably, the width of each reaction wall is preferably 10 to 50 m and the thickness is 1 to 3 m. The depth is preferably 5 to 20 m.

Complex contaminated groundwater can be purified by installing the multi-stage vegetative reaction wall in the horizontal axis direction with respect to the movement direction of the groundwater contaminant. That is, the primary reaction wall is installed by arranging a plurality of rows planted with herbaceous purified plants on the ground in the horizontal direction with respect to the moving direction of the groundwater pollutant at regular intervals, and the primary reaction wall section is spaced apart from the primary reaction wall section. Arrange a plurality of rows of planted woody plants that can reach the groundwater level near the groundwater level at regular intervals in the horizontal axis with respect to the movement direction of the pollutant, and by an external compressor installed on the ground between the plants of each row. A plurality of air inlet pipes are installed up to the groundwater contamination zone so that a uniform oxygen supply can be made to the groundwater contamination zone, and a secondary reaction wall is installed, and the secondary reaction wall is spaced apart from the secondary reaction wall to react with contaminants in the groundwater. A trench of a certain thickness carrying a reaction wall that can be removed or detoxified can also be transferred to the groundwater contamination zone. A tertiary reaction wall provided with a long horizontal axis with respect to the movement direction of the aspiration is installed, and finally, there are a plurality of wood-purified plants having the same shape except for the secondary reaction wall and the air inlet tube at regular intervals from the tertiary reaction wall. By installing the fourth reaction wall planted with heat, complex contaminated groundwater can be purified.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited thereto.

EXAMPLE

Installation of Reaction Wall

Four columns each having a height of 1 m and an inner diameter of 30 cm were installed. Yellow irises, herbaceous plants, were planted in the primary soil column, poplar and air inlet tubes were installed in the secondary soil column, bentonite was filled in the upper 15cm, and zeolite, the reactant, was filled in the lower column. Poplar was planted in the 4th soil column and used as the final section. Four columns were connected to each other, and the groundwater layer was adjusted to 40 cm in each column, and the flow rate of the groundwater was adjusted to 10 ^-5 cm / sec similarly to the field conditions.

Purification Ability Test

The test was initiated when the root ends of the poplars planted in the fourth soil column grew close to the groundwater layer. Contamination conditions were evenly sprayed with 5 g of complex fertilizer containing the same concentration of ammonia nitrogen and phosphate on the first column soil, and a constant amount of water was injected periodically to keep the groundwater flow rate constant. The experiment was conducted for about 6 months, and the final treatment results in the steady state are shown in Table 1.

[Table 1: Column experiment result table] (Unit: mg / L)

pollutant After the first reaction wall After the second reaction wall After the third reaction wall After the fourth reaction wall Ammonia nitrogen 30 8 - - nitrate 4 10 4 One phosphate 3 - - -

The concentration of ammonia nitrogen in the water passed through the primary column in which the herbaceous plants were planted was about 30 mg / L and the nitrate concentration was 4 mg / L, whereas the concentration of phosphate was about 3 mg / L. Therefore, it was found that most of the phosphate was filtered in the primary column. The concentration of ammonia nitrogen in the water passed through the secondary column equipped with poplar and air injection tube was 8 mg / L and nitrate nitrogen was 10 mg / L, but the phosphate concentration was below the detection limit. Therefore, some of the ammonia nitrogen components were converted to nitrate by nitrification, and some of them were removed in the column. The concentration of ammonia nitrogen in the effluent passed through the zeolite-filled tertiary column was below the detection limit, and the concentration of nitrate nitrogen was 4 mg / L, indicating that most of the ammonia nitrogen was adsorbed on the zeolite. . The concentration of nitrate nitrogen in the effluent passed through the fourth column with poplar was less than 1 mg / L, indicating that the treatment of groundwater contaminated with nitrogen and phosphorus by using multi-level plant reaction walls can be effectively performed. .

When the groundwater is purified using the multi-level plant reaction wall according to the present invention, the complex pollutants can be effectively removed continuously while maintaining the optimum operating conditions according to the characteristics of the complex pollutants, and the power energy required for operation is minimized. By adopting an unmanned operation system that does not require the input of manpower, it can treat complex contaminated groundwater in the long term (at least 10 years) with high processing performance and economical efficiency compared to simple process structure.

In addition, the reaction wall of the present invention provides an environmentally friendly process having excellent appearance and little other contaminant by-products by using plants.

Claims (12)

It comprises a primary reaction wall in which the herbaceous plant is planted, a secondary reaction wall in which the tree plant is planted, a tertiary reaction wall containing the adsorption medium, and a quaternary reaction wall in which the tree plant purification plant is planted. Multi-level plant reaction wall characterized by. The method of claim 1, wherein the primary reaction wall, the secondary reaction wall and the quaternary reaction wall, each of the purified plants are planted at regular intervals in the transverse direction with respect to the flow direction of the contaminated groundwater, the row is composed of a plurality of rows Multi-level flora reaction wall characterized in that. According to claim 1, wherein the herbaceous plant is a multi-level plant reaction wall, characterized in that the perennial herbaceous plants having a root depth of about 1m and a radial root distribution. The method of claim 1, wherein the herbaceous plant is one or more plants selected from the group consisting of sunflower, horsetail, goose, mugwort, evening primrose, silver grass, parrot hair, aquatic horsefly, laver, rye, reed and alfalfa Multi-level plant reaction wall, characterized in that. The multi-level plant reactive wall according to claim 1, wherein the tree plant-purified plant installed in the secondary or quaternary reaction wall has roots having a depth of 2 to 5 m or more and a growth period of 1 to 2 years. . [Claim 2] The multi-level plant reaction wall according to claim 1, wherein the tree plant purifying plant is selected from the group consisting of hybrid poplar, willow, rapeseed and aspen. The multi-stage plant reaction wall according to claim 1, wherein the secondary reaction wall includes a plurality of air inlet pipes embedded in the contaminated groundwater zone at regular intervals between the woody plant purification heats. 8. The multi-stage vegetative reaction wall according to claim 7, wherein a plurality of air permeation holes are provided in the underground buried portion of the air injection pipe. The multi-stage plant reaction wall according to claim 1, wherein the secondary reaction wall and the quaternary reaction wall are mixed with wood-purified plants and herbal-purified plants. According to claim 1, At the rear end of the planting section of the quaternary reaction wall to the groundwater layer arranged in a line at a predetermined interval on the ground so as to perform a real-time water quality measurement of the final treated groundwater in a differential depth A multi-stage plant reaction wall comprising a plurality of groundwater monitoring wells and an extraction pump. The multi-step plant reaction wall according to claim 1, wherein each of the reaction walls has a width of 10 to 50 m, a thickness of 1 to 3 m, and a depth of 5 to 20 m. 12. A method for the purification of complex contaminated groundwater, wherein the multistage vegetative reaction wall of any one of claims 1 to 11 is installed in a transverse direction relative to the movement direction of the groundwater contaminant.