JP7137873B2 - An engineered wetland system suitable for the removal of agricultural pesticide residues in karst areas - Google Patents

Description

Field of the Invention The present invention belongs to the technical field of sewage treatment, and in particular to an artificial wetland system suitable for removing agricultural organic pesticide residues in karst areas.

The karst area, also known as the karst landform area, is an area with obvious characteristics of being rich in calcium and highly alkaline (high carbonate concentration and high pH value), and China is the most widely distributed area. This region is concentrated in provinces such as Guangxi, Guizhou and Yunnan, and is also distributed in provinces (equivalent to counties) and autonomous regions such as Sichuan, Chongqing, Hunan, Shanxi, Gansu and Tibet. Farming in karst areas is unique in the removal of agricultural pesticide residues due to geological and geomorphological influences, and traditional refining techniques can only be applied after undergoing special process design and treatment.

Organochlorine pesticides (OCPs) are one of the typical environmentally persistent pesticides organic pollutants (POPs), are difficult to degrade, bioaccumulate, semi-volatile, and have high It has characteristics such as toxicity. Due to the semi-volatile properties of OCPs, they can volatilize from water and soil into the atmosphere, or adsorb to atmospheric particles, causing long-range transport and precipitation, causing global pollution. Moreover, OCPs in the environment accumulate in the bodies of various organisms through the action of the food chain, causing damage to the nervous system, immune system, endocrine system, and other organs within the organisms, and poses a serious danger to humans and ecosystems. and attracted the attention of the international community, and the "Stockholm Convention on Persistent Organic Pollutants" promulgated by the United Nations Environment Program gradually reduced the use of 21 types of persistent organic pollutants, including organochlorine pesticides. and/or proposed to be eliminated. Since 1970, countries around the world have successively banned the manufacture and use of OCPs, and China began banning their manufacture and use in 1980. Although it has been decades since the ban, OCPs are persistent and there are still plenty of residues, not only in China but around the world.

Hexachlorocyclohexanes (HCHs) are common organochlorine pesticides and are often detected in the environment. Among them, β-HCH is the most stable among its various isomers. In the natural environment, it is difficult to be decomposed by abiotic decomposition such as photolysis and hydrolysis, and is relatively slow to be degraded by microorganisms. Residues in the

Constructed wetlands are ecosystems that treat sewage by artificially utilizing ground soil and fillers (substrates) and growing plants on selectively designed substrates. It is considered to be one of the good methods. According to foreign studies and surveys, North American and Nordic countries usually treat polluted rivers with artificial wetlands to solve the problem of non-point source pollution of pesticides in their own countries. The plants selected for this have shown deficiencies such as poor adaptability to calcium-rich and highly alkaline soils and slow bioconcentration/clearance rates for contaminants.

In view of the above, the present invention aims to provide an artificial wetland system suitable for removing residual agricultural pesticides in karst areas. With strong adaptability to conditions, persistent organic pesticides have excellent bioaccumulation and absorption and degradation effects by plants.

The present invention implements a variety of infill bed designs for artificial wetlands, a soil layer with abundant calcium and high alkalinity tolerance, and plant species suitable for the chemical properties of karst water. Providing a variety of plants, the system has the advantage of withstanding high calcium and high alkaline water quality, and has an efficient purification effect on OCPs adversely affected by Ca ²⁺ and HCO ₃ ^2- ions. .

To achieve the above objects of the present invention, the present invention provides the following technical solutions.
The present invention provides an artificial wetland system suitable for removing agricultural organic pesticide residues in karst areas, which is composed of a pebble layer, a soil layer and a plant layer in order from bottom to top,
A water inlet is installed at the top of the artificial wetland system, a wastewater collection system is installed at the bottom of the artificial wetland system,
The waste water collection system includes a plurality of perforated pipes with a diameter of 0.5-5 cm and a water collecting main pipe , the surface of the perforated pipe is wrapped with a strainer, and the water in the water collecting main pipe is an outlet is located outside said artificial wetland system;
In the plant layer, one or more of calamus, canna, thalia (Latin notation: Thalia dealbata Fraser), and typha (Latin notation: Typha angustifolia L.) are planted,
The thickness ratio of the pebble layer and the soil layer is 1:(1.5-2.5).

Preferably, the soil layer contains red soil and/or biochar.

Preferably, the amount of red clay added is between 1% and 3% of the total mass of the soil layer.

Preferably, the amount of biochar added is 3%-5% of the total mass of the soil layer, and the particle size of biochar is 10-40 mesh.

Preferably, the biochar is added to a depth of 3 cm or more from the surface of the soil layer.

Preferably, the height of the calamus and canna is 1.3 to 1.5 m.

Preferably, the pebbles have a particle size of 3-4 cm.

Preferably, the hole diameter of the strainer wound on the surface of the perforated pipe is 80-200 mesh.

Preferably, said artificial wetland system is incorporated into a container.

Preferably the container is an aluminum container.

The artificial wetland system suitable for removing agricultural residual organic pesticides in karst regions provided by the present invention has a simple structure, low cost, and cooperation of pebble layer, soil layer and plant layer, especially biochar to the soil layer. Through technical manipulations such as doping and selection of special plants, the adaptability of the system to karst hydrogeological conditions is improved, and persistent organic pesticides have excellent bioconcentration and plant absorption and degradation effects. According to the description of the examples, the artificial wetland system provided in the present invention has a good treatment effect for water areas contaminated with low concentrations of organochlorine pesticide β-HCH, and the artificial wetland system in which different plants are cultivated. Data are provided as a reference on the effectiveness of wetlands in purging β-HCH.

Schematic of a vertical subsoil artificial wetland system for treating organic pesticides prepared in Example 1 of the present invention. 1 is the water inlet, 2 is the non-vegetated area, 3 is the planted area, 4 is the soil layer (red soil, doped with biochar), 5 is the pebble layer, and 6 is the drainage outlet. Variation of β-HCH content in artificial wetland water with different plants in Example 1 of the present invention. K is the blank comparison group, 1-1 in FIG. 2A, 2-1 in FIG. 2B, and 3-1 in FIG. 2C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. -2, and 3-2 in FIG. 2C are three groups of parallel canna-grown artificial wetlands. Figures 2A, 2B, and 2C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands with different plants, respectively. Variation of β-HCH content in artificial wetland water with different plants in Example 1 of the present invention. K is the blank comparison group, 1-1 in FIG. 2A, 2-1 in FIG. 2B, and 3-1 in FIG. 2C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. -2, and 3-2 in FIG. 2C are three groups of parallel canna-grown artificial wetlands. Figures 2A, 2B, and 2C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands with different plants, respectively. Variation of β-HCH content in artificial wetland water with different plants in Example 1 of the present invention. K is the blank comparison group, 1-1 in FIG. 2A, 2-1 in FIG. 2B, and 3-1 in FIG. 2C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. -2, and 3-2 in FIG. 2C are three groups of parallel canna-grown artificial wetlands. Figures 2A, 2B, and 2C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands with different plants, respectively. In Example 1 of the present invention, the transition of the content of β-HCH in the root zone substrate of the artificial wetland with different plants, where K is the blank comparison group, 1-1 in FIG. 3A, 2 in FIG. 3B -1, and 3-1 in FIG. 3C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. 3A, 2-2 in FIG. 3B, and 3-2 in FIG. 3C are parallel canna cultivation artificial wetlands are three groups of FIGS. 3A, 3B, and 3C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands of different plants, respectively. In Example 1 of the present invention, the transition of the content of β-HCH in the root zone substrate of the artificial wetland with different plants, where K is the blank comparison group, 1-1 in FIG. 3A, 2 in FIG. 3B -1, and 3-1 in FIG. 3C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. 3A, 2-2 in FIG. 3B, and 3-2 in FIG. 3C are parallel canna cultivation artificial wetlands are three groups of FIGS. 3A, 3B, and 3C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands of different plants, respectively. In Example 1 of the present invention, the transition of the content of β-HCH in the root zone substrate of the artificial wetland with different plants, where K is the blank comparison group, 1-1 in FIG. 3A, 2 in FIG. 3B -1, and 3-1 in FIG. 3C are three groups of parallel calamus cultivation artificial wetlands, 1-2 in FIG. 3A, 2-2 in FIG. 3B, and 3-2 in FIG. 3C are parallel canna cultivation artificial wetlands are three groups of FIGS. 3A, 3B, and 3C are line graphs representing the change in β-HCH content over time in the first, second, and third groups of artificial wetlands of different plants, respectively.

The present invention provides an artificial wetland system suitable for removing agricultural organic pesticide residues in karst areas, which is composed of a pebble layer, a soil layer and a plant layer in order from bottom to top, and a water inlet at the top of the artificial wetland system. is installed, a drainage collection system is installed at the bottom of the artificial wetland system, the drainage collection system includes a plurality of perforated pipes with a diameter of 0.5 ~ 2 cm and a water collection main pipe, the perforated pipe the surface of the perforated pipe is wrapped in a strainer, the water outlet of said perforated pipe is located outside said artificial wetland system, said plant layer is planted with one or more of calamus, canna, thalia, typha, and said The thickness ratio of the pebble layer and the soil layer is 1:(1.5-2.5).

In the present invention, said artificial wetland system is preferably set shape according to site conditions, preferably rectangular, optionally said artificial wetland system digs a rectangular ditch as a container. Containers made of other materials such as aluminum containers, stainless steel containers or plastic plate containers can also be used in the present invention.

In the present invention, pebbles are laid as the pebble layer, the particle size of the pebble is preferably 3 to 4 cm, the thickness of the pebble layer is preferably 10 to 50 cm, more preferably 20 to 40 cm, and the The function of the pebble layer is to block soil from entering the catchment system and improve the collection efficiency of treated wastewater. In the present invention, the thickness ratio of the pebble layer and the soil layer is preferably 1:(1.8-2.2), more preferably 1:2.

In the present invention, the soil layer is laid with soil, and the thickness of the soil layer is preferably 20 to 100 cm. In the present invention, the soil layer preferably contains red soil and/or biochar. In the present invention, the amount of red soil added is preferably 1% to 3%, more preferably 2%, of the total mass of the soil layer, and the red soil is preferably mixed uniformly with the original soil. , improve the viscosity of the original soil. The present invention is not particularly limited in the source of red clay, and conventional red clay in the field can be used. In the present invention, the function of red soil is to increase soil viscosity and reduce soil loss. In the present invention, the amount of biochar added is preferably 3% to 5%, more preferably 4%, of the total mass of the soil layer. ~40 mesh, the biochar is preferably mosouchi charcoal and/or eucalyptus charcoal, and in the present invention, biochar is preferably added 3 to 5 cm or less from the surface of the soil layer, The thickness of the soil applied is preferably set between 10 and 30 cm, depending on the type and root system of the plant to be planted. In the present invention, the function of the biochar is to reduce the density of soil, and the soil to which the biochar is added can enhance the function of adsorbing and concentrating pollutants, and target pollutants by plant roots. beneficial for the absorption and purification of

In the present invention, the plant layer is preferably planted with calamus or canna, and the height of calamus and canna is preferably 1.3 to 1.5 m, more preferably 1.4 m. . The present invention preferably selects lush plants for transplantation. In the present invention, said calamus, canna, thalia, typha are highly adaptable to soils rich in calcium and highly alkaline (high carbonate concentration, high pH value).

In the present invention, the water inlet is installed at the top of the artificial wetland system. The present invention does not particularly limit the water inlet as long as the water inlet function can be realized.

In the present invention, a wastewater collection system is installed at the bottom of the artificial wetland system, the wastewater collection system includes a plurality of perforated branch pipes with a diameter of 0.5-5 cm, and the perforated branch pipes are the water collection main pipes. The water collecting main pipe has a diameter of 2-10 cm, and the water collecting main pipe is connected to the water outlet through a detachable connector. The surface of the perforated pipe is wrapped in a strainer, the mesh of the strainer is preferably 80-200 mesh, more preferably 100 mesh, and the function of the strainer is to allow the mud sample to enter the pipe and cause clogging. It is to prevent In the present invention, the water outlet of said perforated pipe is located outside the artificial wetland system. In the present invention, the water outlet is preferably connected to an outlet valve for discharging water. In the present invention, a constant pressure vent pipe is preferably installed at the drain outlet, the height of the constant pressure vent pipe is equal to the height of the artificial wetland system, and the function of the constant pressure vent pipe is the repairability of the drain pipe and It is to ensure constant pressure and stable drainage. In the particular practice process of the present invention, influent enters at the top of the engineered wetland system, is naturally evenly distributed, passes through the engineered wetland system, permeates the wastewater collection system, and concentrates to drain.

In the present invention, the artificial wetland system can preferably be installed with a prefabricated reactor, preferably the prefabricated reactor is made of stainless steel, aluminum plate or plastic plate; It can only be installed on site after it has been commissioned outside. The prefabricated reactor of the present invention is capable of releasing all the water in the prefabricated reactor 20-40 days after the plant is grown, specifically during off-site commissioning, preferably the plant 30 days after the cultivation of β - Preparation water containing HCH, preferably tap water is added at appropriate points during the experiment so that the liquid level in the system does not change.

The technical solutions provided by the present invention are described in detail together with the embodiments below, but they should not be understood as limiting the protection scope of the present invention.

[Example 1]
A vertical subsoil artificial wetland system for treating organic pesticides, comprising:
The miniature simulated vertical subsoil artificial system was built into a rectangular aluminum container (specifications: length x width x height = 1 m x 0.5 m x 0.6 m), and a 2 cm diameter Install a drainage outlet, a water collection main pipe is connected inside the drainage outlet to collect water samples, a perforated branch pipe is connected to the water collection main pipe in a "non" shape, and the perforated pipe is , with a diameter of 2 cm, the perforated pipe has a hole with a diameter of 0.5 cm, wrapped in three layers of 100-mesh filter cloth to prevent mud from clogging the pipe, and outside the drain is connected to a drain faucet. Divide the center of the container into two areas of the same volume with a 300 mesh strainer (area specifications: length x width x height = 0.5m x 0.5m x 0.6m), and divide the two areas At the bottom of both, 10 cm thick pebbles (particle size 3-4 cm) are laid, and 20 cm thick soil is laid above the pebbles to increase soil viscosity and reduce soil loss. For this reason, 2% of the total mass of the soil layer is added with red soil, and 3% of mosouchiku charcoal is added. The prepared soil is usually set to 3 cm or less of the soil layer, planting calamus and canna in one area of the two wetland devices, and leaving the other area unplanted (the specific structure of the artificial wetland system (see Figure 1).

In this example, the planted calamus and canna were purchased from flower bases, and mainly selected bush calamus and canna with a height of about 1.4 m were transplanted into the artificial wetland system to create a new growing environment. After adaptation and planting the plants, tap water (PH is 6.9, dissolved oxygen is 4.70 mg/L) was added to the system, the water level was kept at 5 cm above the soil, and the plants were grown for 30 days before watering. and add 60 L of β-HCH laboratory make-up water with a concentration of 20 μg/L per system, where 60 L of contaminated water per system is added to provide sufficient nutrients for the plants. Add 500 mL of solution. Three parallels were created for each plant variety and one blank comparison system with the same substrate but without plants was set up: 3 calamus artificial wetland systems, 3 canna artificial wetland systems and 1 plant. It is a blank comparison system without During the experiment, tap water was added at appropriate times so as not to change the liquid level in the system.

Using the engineered wetland system of this example for 60 days, seven engineered wetland water samples were periodically collected and analyzed by solid phase extraction gas chromatography of different plants in the engineered wetland water according to the planned test method. The content of β-HCH (see Table 1 for the results) and the trend of change in the content of β-HCH in the artificial wetland water of each group (the results are shown in Figures 2A to 2C) were detected.
Among them, the calamus wetland system has the highest average removal rate of β-HCH at 95.03%, followed by the Kanna wetland system at 93.35%.

Note: K is plant-free artificial wetlands, 1-1, 2-1 and 3-1 are three side-by-side iris artificial wetlands, 1-2, 2-2 and 3-2 are three side-by-side canna artificial wetlands. It is a wetland.

Within 60 days of commissioning, periodically collect soil samples of the artificial wetland and detect the content of β-HCH in the artificial wetland soil of different plants by solid-phase extraction gas chromatography according to the planned test method. Then, the content of β-HCH in the soil of the plant root zone (see Table 2) and the change tendency (see FIGS. 3A to 3C) were determined. Among them, for soils in the root zone, the calamus wetland system had the highest average removal rate of β-HCH at 57.21%, followed by the Kanna wetland system at 52.65%.

Note: K is plant-free artificial wetlands, 1-1, 2-1 and 3-1 are three side-by-side iris artificial wetlands, 1-2, 2-2 and 3-2 are three side-by-side canna artificial wetlands. It is a wetland.

[Example 2]
A vertical subsoil artificial wetland system for treating organic pesticides, comprising:
A vertical subsoil artificial wetland system is constructed in a natural wetland in a farmland of a village in Guilin City and is multi-unit. The size and processing of the unit structure are described below.

The unit system uses an excavated trough as a treatment container (specifications: length x width x height = 5m x 2.5m x 1.2m), with a 10cm diameter drainage hole 5cm from the bottom of the container. , the water collecting main pipe is connected to the inside of the outlet to collect water samples, the perforated branch pipe is connected to the water collecting main pipe in a "non" shape, the perforated pipe has a diameter of is 10 cm, and the perforated pipe has a hole with a diameter of 1.0 cm, wrapped in three layers of 100 mesh filter cloth to prevent mud from clogging the pipe, and outside the drain, A ball valve is connected to control the drainage. At the bottom of the container, 25 cm thick pebbles (particle size 3-4 cm) are laid, and 50 cm thick soil is laid on top of the pebbles to increase soil viscosity and reduce soil loss. Then, 2% of the total mass of the soil layer is added with red soil, and 3% of mosouchiku charcoal is added. The soil is placed no more than 5 cm in the soil layer and the bushes are planted in a square trough artificial wetland.

In this example, the planted calamus was purchased from a local flower base, and a bushy calamus with a height of 1.4 m was selected and transplanted into the artificial wetland system to adapt to the new growing environment. After planting the plants, the system was fed with natural wetland to farmland ditch water (PH of 7.9, dissolved oxygen of 6.5 mg/L, average total nitrogen value of 2.55 mg/L, and average total phosphorus value of 0.16 mg). /L)) was added, the water level was kept 5 cm above the soil, and after the plants had grown for 30 days, all the water was drained, and the soil was 2-7 μg/L (average 5 μg /L) of β-HCH is prepared and added to the simulated ditch water, the nitrogen and phosphorus nutrients contained in the ditch water can provide sufficient nutrients for plant growth. During the experiment, a flow meter is used to control the amount of water being treated, and the opening of the ball valve in the drain pipe is adjusted to keep the liquid level in the constructed wetland system essentially stable.

The artificial wetland in this example is continuously watered and discharged, and soil samples of the artificial wetland are periodically collected within 60 days from the trial operation, and solid-phase extraction gas chromatography is performed according to the planned test method. The content of β-HCH in the effluent of the artificial wetland was detected, and the content of β-HCH in the soil of the plant root zone (see Table 3) was measured. According to the operation results, the removal rate of β-HCH is 83.5% to 95.2% and the average removal rate is 89.5% for the simulated farmland ditch water.

From the data of the above examples, the artificial wetland system provided by the present invention can effectively remove β-HCH in water and soil, and the artificial wetland system is good for organic pollution of water environment and soil environment. It can be seen that it has a significant cleaning effect and can provide data reference for the cleansing effect of various plants in artificial wetlands in the β-HCH cleansing process.

The above are merely preferred embodiments of the present invention, and without departing from the principles of the present invention, those skilled in the art can make several improvements and modifications, and these improvements and modifications also constitute the present invention. should be regarded as the protection scope of

Claims (10)

An artificial wetland system suitable for the removal of agricultural organic pesticide residues in karst areas, comprising:
Place the pebble layer, soil layer, and plant layer in order from bottom to top,
A water inlet is installed at the top of the artificial wetland system, a wastewater collection system is installed at the bottom of the artificial wetland system,
The wastewater collection system includes a plurality of perforated pipes with a diameter of 0.5 to 5 cm and a water collection main pipe , the surface of the perforated pipe is wrapped with a strainer, and the water in the water collection main pipe is an outlet is located outside said artificial wetland system;
The plant layer is planted with one or more of calamus, canna, thalia, and typha;
An artificial wetland system characterized in that the pebble layer and the soil layer have a thickness ratio of 1:(1.5 to 2.5). 2. The engineered wetland system of claim 1, wherein the soil layer comprises red soil and/or biochar. The artificial wetland system according to claim 2, wherein the amount of red soil added is 1% to 3% of the total mass of the soil layer. The artificial wetland system according to claim 2, wherein the amount of biochar added is 3% to 5% of the total mass of the soil layer, and the particle size of the biochar is 10 to 40 mesh. The artificial wetland system according to claim 2 or 4, characterized in that the biochar is added to a depth of 3 cm or more from the surface of the soil layer. The artificial wetland system according to claim 1, characterized in that the height of each of the irises and the canna is 1.3 to 1.5 m. 2. The artificial wetland system of claim 1, wherein the pebbles have a particle size of 3-4 cm. The artificial wetland system according to claim 1, characterized in that the strainer wound around the surface of the perforated pipe has a pore size of 80 to 200 mesh. 2. The constructed wetland system of claim 1, wherein said constructed wetland system is incorporated into a container. 10. The constructed wetland system of claim 9, wherein said container is an aluminum container.

Images