Method for treating non-point source pollution by using river channel slope

Abstract

The present application belongs to the field of non-point source pollution treatment, and provides a method for treating non-point source pollution by using river slope. The method comprises the following steps: setting at least two guide plates at the river slope where non-point source pollution wastewater flows into the river, the upper end and the lower end of the guide plate being connected with the top and the bottom of the slope respectively, and forming a non-point source pollution treatment area between the guide plates; digging a plurality of discrete filler pits on the slope surface of the non-point source pollution treatment area, fixing filler bags containing carbon-based functional materials or environmental functional materials in the filler pits, and making the filler bags protrude from the slope surface; introducing non-point source pollution wastewater into the non-point source pollution treatment area or adding an oxidizing agent while introducing the wastewater, and the wastewater contacts with the materials in the filler bags during flowing through the non-point source pollution treatment area to realize adsorption or adsorption and degradation of pollutants. The present application provides an effective way for treating non-point source pollution, and can reduce the threat of non-point source pollution to the ecological environment of rivers.

Description

Technical Field

[0001] This invention belongs to the field of non-point source pollution control and relates to a method for non-point source pollution control using riverbank slopes. Background Technology

[0002] Non-point source pollution mainly includes runoff from rural irrigation water, rural wastewater, and surface rainwater runoff. Direct discharge of untreated non-point source pollution is one of the main causes of the deterioration of river and lake water environments. Due to the widespread and unique nature of non-point source pollution, the volume of polluted water is enormous. Treatment using traditional point source pollution control technologies such as wastewater treatment plants faces numerous problems, including high costs, large land areas required, and operational difficulties. Furthermore, non-point source pollution contains a complex variety of pollutants, including organic pollutants, heavy metal pollutants, and nitrogen and phosphorus pollutants, with significant concentration differences, making removal difficult through the river's self-purification function. Some studies have attempted to treat non-point source pollution through biological remediation methods such as plant absorption and microbial metabolism, but these still face problems such as low treatment efficiency and the inability or even complete removal of some pollutants.

[0003] While the removal of pollutants from non-point source pollution using solid-phase materials through catalytic oxidation, reduction, and adsorption demonstrates potential, the treatment efficacy of solid-phase catalytic materials is unsatisfactory due to difficulties in fixation and short hydraulic retention times, hindering its practical application. Therefore, non-point source pollution continues to pose a serious threat to river water quality, necessitating the development of more effective non-point source pollution control technologies.

[0004] Riverbank slopes are sloping surfaces adjacent to the water surface on both sides of a river, and are important hydraulic structures ensuring the normal functioning of a river. Currently, the development of riverbank slopes mainly focuses on their role in protecting the river's water conservancy functions, with little research into their ecological management capabilities. As a crucial pathway for non-point source pollution entering rivers, if riverbank slopes can be structurally designed and equipped with environmentally friendly materials to enable them to manage non-point source pollution, effectively removing pollutants as wastewater flows through them, it will have a positive impact on non-point source pollution control. Summary of the Invention

[0005] In response to the serious threat that non-point source pollution poses to the ecological environment of rivers, and the lack of effective methods for its control, this invention provides a method for non-point source pollution control using riverbank slopes, thus offering an effective approach to the treatment of non-point source pollution.

[0006] To achieve the above-mentioned objectives, the technical solution adopted by the present invention is as follows:

[0007] The method of using riverbank slopes for non-point source pollution control includes the following steps:

[0008] (1) Preparation of biochar-based functional materials

[0009] Biochar precursors are calcined at 200–1500 °C to obtain biochar. Biochar, non-metallic element precursors and metal salts are thoroughly mixed to obtain reaction precursors. The reaction precursors are calcined at 200–1500 °C to obtain biochar-based functional materials.

[0010] The non-metallic element precursor is a compound containing at least one of fluorine, sulfur, oxygen, nitrogen, and phosphorus, and the metal salt is at least one of iron salt, copper salt, cobalt salt, and nickel salt.

[0011] (2) At least two guide plates shall be installed on the riverbank where non-point source pollution wastewater flows into the river. The upper and lower ends of the guide plates shall connect to the top and bottom of the slope, respectively. The area between the guide plates shall be the non-point source pollution treatment area. The length of the guide plate shall be at least twice the distance between the top and bottom of the slope, and the distance between adjacent guide plates shall be 1 to 5 m.

[0012] Several discretely distributed filling pits are dug on the slope of the non-point source pollution control area. The total area of ​​each filling pit on the slope accounts for 5% to 80% of the slope area of ​​the non-point source pollution control area. Biochar-based functional materials or environmental functional materials are wrapped in a mesh with micron-sized pores to form filling bags. The filling bags are fixed in each filling pit so that the filling bags protrude from the slope.

[0013] The environmental functional material is formed by fully mixing biochar-based functional materials and solid oxidants. The solid oxidants are solid oxidants that are insoluble or slightly soluble in water, or water-soluble solid oxidants loaded in slow-release materials.

[0014] (3) When the packing bag described in step (2) does not contain a solid oxidant, a liquid oxidant is added to the non-point source pollution wastewater upstream of the non-point source pollution treatment zone to form non-point source pollution wastewater containing oxidant materials. The liquid oxidant is a liquid oxidant material, an aqueous solution of a liquid oxidant material, or an aqueous solution of a solid oxidant material. The non-point source pollution wastewater containing oxidant materials is introduced into the non-point source pollution treatment zone. The wastewater comes into contact with biochar-based functional materials during its flow through the non-point source pollution treatment zone. The biochar-based functional materials and oxidant materials degrade and adsorb the pollutants in the wastewater, thereby removing the pollutants from the wastewater and achieving the treatment of non-point source pollution wastewater.

[0015] Alternatively, when the packing bag described in step (2) does not contain a solid oxidant, the non-point source pollution wastewater is introduced into the non-point source pollution treatment zone. The wastewater comes into contact with the biochar-based functional material during the flow through the non-point source pollution treatment zone. The biochar-based functional material adsorbs the pollutants in the wastewater, removes the pollutants in the wastewater, and achieves the treatment of non-point source pollution wastewater.

[0016] When the packing material in step (2) contains a solid oxidant, the non-point source pollution wastewater is introduced into the non-point source pollution treatment area. During the process of the wastewater flowing through the non-point source pollution treatment area, it comes into contact with the environmental functional materials. The environmental functional materials degrade and adsorb the pollutants in the wastewater, remove the pollutants in the wastewater, and achieve the treatment of non-point source pollution wastewater.

[0017] In step (1) of the above technical solution, the contents of biochar, non-metallic element precursor and metal salt in the reaction precursor are preferably 50wt% to 90wt%, 4wt% to 20wt% and 6wt% to 30wt%, respectively.

[0018] In step (1) of the above technical solution, the non-metallic element precursor is at least one of fluoride salt, sulfide salt, nitrate, ammonium salt, phosphate, pyrophosphate, oxalic acid, and thiocyanate.

[0019] In the above technical solution, the content of solid oxide material in the environmental functional material is preferably 5wt% to 30wt%.

[0020] In the above technical solution, when step (3) requires adding liquid oxidant to the non-point source pollution wastewater upstream of the non-point source pollution treatment area to form non-point source pollution wastewater containing oxidant materials, the amount of liquid oxidant added is determined according to the type of oxidant materials in the liquid oxidant and the type of pollutants to be degraded in the non-point source pollution wastewater. Generally, the concentration of oxidant materials in the resulting non-point source pollution wastewater containing oxidant materials can be controlled to be 10. -7 wt% to 1wt%. In practical applications, the specific concentration of oxidizing materials in non-point source pollution wastewater can be determined experimentally based on the type of oxidizing material and the pollutants to be degraded.

[0021] In the above technical solution, the oxidizing material is calcium peroxide, persulfate, potassium permanganate, potassium dichromate, hydrogen peroxide, or peracetic acid. Calcium peroxide is a slightly water-soluble solid oxidizing material, which is directly mixed with biochar-based functional materials to form environmental functional materials during use. Persulfate, potassium permanganate, and potassium dichromate are water-soluble solid oxidizing materials, which can be loaded onto slow-release materials and then mixed with biochar-based functional materials to form environmental functional materials, or they can be dissolved in water to form liquid oxidants added to non-point source pollution wastewater. The slow-release material is a commonly used slow-release material in the prior art, including biodegradable polymer materials and inorganic slow-release materials, such as paraffin wax, resin, sodium alginate, polymer-based materials, chitosan-based natural polymer materials, starch-based natural polymer materials, etc. Hydrogen peroxide and peracetic acid are liquid oxidizing agents. In use, hydrogen peroxide or peracetic acid is added as a liquid oxidant to the non-point source pollution wastewater, or an aqueous solution of hydrogen peroxide or a water-soluble solution of peracetic acid is added as a liquid oxidant to the non-point source pollution wastewater. In the above technical solutions, when it is necessary to add a liquid oxidant to the non-point source pollution wastewater upstream of the non-point source pollution treatment area to form non-point source pollution wastewater containing oxidizing materials, the liquid oxidant can be slowly added via a pump or dripping device in front of or at the inlet of the non-point source pollution treatment area.

[0022] In the above technical solution, the environmental functional material is composed of biochar-based functional materials and solid oxidants in particles with a particle size in the micrometer or millimeter range.

[0023] In step (1) of the above technical solution, the biochar precursor includes, but is not limited to, animal-based carbon-containing products, plant-based carbon-containing products, and carbon-containing waste.

[0024] In step (1) of the above technical solution, biochar or biochar-based functional materials can be prepared by calcination in an atmosphere of air, oxygen, nitrogen, argon or a mixture of the above gases.

[0025] In step (1) of the above technical solution, when preparing biochar or biochar-based functional materials by calcination, it is preferable to control the calcination temperature to be 400-1000℃ and the calcination time to be 1-4h.

[0026] In the above technical solution, the proportion of the total area of ​​each filling pit on the slope to the area of ​​the non-point source pollution treatment zone is determined according to the water quality and flow rate of the non-point source pollution wastewater. If the concentration of pollutants in the non-point source pollution wastewater is relatively high, the degradation difficulty of the pollutants in the non-point source pollution wastewater is relatively high, or the flow rate of the non-point source pollution wastewater is relatively large, then the proportion of the total area of ​​each filling pit on the slope to the area of ​​the non-point source pollution treatment zone should be increased.

[0027] In the above technical solution, the number of filling pits is determined according to the area of ​​the non-point source pollution treatment area. The larger the area of ​​the non-point source pollution treatment area, the more filling pits there are. In practical applications, at the very least, at least 5 filling pits are set in the non-point source pollution treatment area.

[0028] In the above technical solution, the filler pit array is distributed on the slope of the non-point source pollution control area. For example, the filler pits can be arranged in multiple rows and columns, and the filler pits can be staggered.

[0029] In the above technical solution, fixing the packing bags in each packing pit and making them protrude from the slope mainly serves two purposes: firstly, it increases the contact area between the wastewater and the packing bags; secondly, it increases the resistance to wastewater flow by utilizing the portion of the packing bags protruding from the slope, thereby increasing the residence time of wastewater in the non-point source pollution treatment area. In practical applications, the height of the packing bags protruding from the slope can be determined based on the actual wastewater flow velocity. When the wastewater flow velocity is high, the height of the packing bags protruding from the slope can be increased. Generally speaking, the height of the packing bags protruding from the slope does not exceed the depth of the wastewater on the slope.

[0030] In step (2) of the above technical solution, the filling bag can be fixed in each filling pit by backfilling the gap between the filling bag and the filling pit with soil and gravel, or by driving fixed piles around the filling pit.

[0031] To prevent damage to the overall structure and contents of the packing bags, in step (2) of the above technology, after fixing the packing bags in each packing pit, a grid cover can be installed over the packing bags. Furthermore, to facilitate the replacement of the packing bags with new ones when the contents of the packing bags have reached the end of their service life, the grid cover is preferably fixed to the slope of the non-point source pollution control area in a detachable manner, or a packing bag replacement port can be provided on the grid cover, which can be opened and closed.

[0032] In the above technical solution, the guide plate is straight, polygonal, or curved, or a combination of two or more of these shapes. The structure of the guide plate is mainly used to regulate the flow pattern and residence time of non-point source pollution wastewater in the non-point source pollution treatment area. In practical applications, a suitable guide plate structure can be selected based on the water quality and flow rate of the non-point source pollution wastewater.

[0033] In the above technical solution, in order to increase the uniformity of the distribution of non-point source pollution wastewater in the non-point source pollution treatment area, especially when the distance between adjacent guide plates is large, such as when the distance between adjacent guide plates exceeds 3m, a water distributor can be installed at the entrance of the non-point source pollution treatment area.

[0034] Compared with the prior art, the technical solution provided by the present invention has the following beneficial technical effects:

[0035] 1. This invention provides a method for treating non-point source pollution using riverbank slopes. This method modifies riverbank slopes so that they can perform ecological functions while ensuring the river's water conservancy functions, thereby treating non-point source pollutants flowing through the riverbank slopes and achieving river ecological protection. Specifically, at least two guide plates are installed on the riverbank where non-point source pollution wastewater flows into the river. The upper and lower ends of the guide plates connect to the top and bottom of the slope, respectively, forming a non-point source pollution treatment zone between the guide plates. Then, several discretely distributed filling pits are dug on the slope of the non-point source pollution treatment zone. Biochar-based functional materials or environmental functional materials are wrapped in a mesh with a micron-sized pore structure to form filling bags. The filling bags are fixed in each filling pit, making the filling bags protrude from the slope surface. On this basis, non-point source pollution wastewater is introduced into the non-point source pollution treatment zone, or an oxidant is added at the same time as the wastewater is introduced. As the wastewater flows through the non-point source pollution treatment zone, it comes into contact with the biochar-based functional materials or environmental functional materials. The biochar-based functional materials or environmental functional materials adsorb the pollutants in the wastewater, or simultaneously adsorb and degrade them, thereby achieving the treatment of non-point source pollution wastewater. This invention can solve the problem that non-point source pollution poses a serious threat to the river ecological environment but there is currently no effective method to treat it, providing an effective approach to the treatment of non-point source pollution.

[0036] 2. The method of the present invention can extend the length of the guide plate by selecting the structural form of the guide plate, for example, selecting a straight line, a broken line, a curved line, or a combination of two or more of the straight line, broken line, and curved lines, thereby extending the flow path of non-point source pollution wastewater in the non-point source pollution treatment area, increasing the residence time of the wastewater in the non-point source pollution treatment area, and thus increasing the total contact time between the wastewater and the environmental functional materials or biochar-based functional materials, effectively improving the adsorption and / or degradation efficiency of pollutants.

[0037] 3. In the preparation process of the biochar-based functional material used in the method of the present invention, non-metallic element doping can alter the surface functional groups of the biochar-based functional material, thereby improving its adsorption performance. Furthermore, it can change the electronic structure of the metal active centers, enhancing its catalytic oxidation performance. The present invention uses this biochar-based functional material for adsorption or as a key material in conjunction with an oxidant for the oxidative degradation of pollutants, thus improving the removal efficiency of pollutants.

[0038] 4. Experiments have demonstrated that the method described in this invention has excellent removal effects on organic pollutants in non-point source pollution wastewater. For example, after 1 μmol / L atrazine-simulated wastewater flows through a non-point source pollution treatment area, the removal rate of atrazine by the method described in this invention can reach 78.3%–95.2%. Similarly, after 1–2 mg / L ciprofloxacin-simulated wastewater flows through a non-point source pollution treatment area, the removal rate of atrazine by the method described in this invention can reach 90.1%–95.2%. Furthermore, the removal rate of ciprofloxacin was calculated based on the concentration of the simulated wastewater and the results show that the removal rate of ciprofloxacin is 90.1%–95.4%. Simultaneously, the method described in this invention can also effectively remove pollutants such as metal ions and nitrates from source pollution wastewater. Since actual source pollution wastewater typically contains multiple pollutants, including organic and inorganic pollutants, the above experimental results show that the method described in this invention is feasible for treating actual non-point source pollution wastewater. Moreover, the method described in this invention is simple to operate and low in cost, effectively solving the problems of high treatment costs and difficulties faced by existing non-point source pollution wastewater treatment technologies. Attached Figure Description

[0039] Figure 1 This is a schematic diagram illustrating the non-point source pollution control zone set up on the riverbank slope according to the present invention.

[0040] Figure 2 This is another schematic diagram of the present invention for setting up a non-point source pollution control zone on a riverbank slope.

[0041] Figure 3 This is another schematic diagram of the present invention for setting up a non-point source pollution control zone on a riverbank slope.

[0042] In the diagram, the red lines represent guide vanes, the blue arrows represent the flow path of non-point source pollution wastewater, and the gray circles represent filler packs installed on the slopes of the non-point source pollution treatment area. Detailed Implementation

[0043] The following examples further illustrate the method for non-point source pollution control using riverbank slopes as described in this invention. It should be noted that the following examples are only for further illustration of this invention and should not be construed as limiting the scope of protection of this invention. Any non-essential improvements and adjustments made by those skilled in the art based on the above description of the invention to implement it are still within the scope of protection of this invention.

[0044] Example 1

[0045] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0046] (1) Preparation of biochar-based functional materials

[0047] Using straw as a precursor for biochar, the straw was calcined at 500℃ in air for 2 hours to obtain biochar. The biochar, sodium fluoride, ferric nitrate, and copper nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, sodium fluoride, ferric nitrate, and copper nitrate were 50 wt%, 25 wt%, 12.5 wt%, and 12.5 wt%, respectively. The reaction precursor was calcined at 500℃ in air for 2 hours to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0048] (2) Constructing a simulated riverbank slope

[0049] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 30° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0050] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0051] like Figure 1 As shown, two identical straight guide vanes are installed on the simulated riverbank slope. The upper and lower ends of the straight guide vanes connect to the top and bottom of the slope, respectively. The height direction of the straight guide vanes is perpendicular to the slope surface, and the angle between the length direction of the straight guide vanes and the bottom of the slope (the boundary between the slope and the water surface) is 30°. The two straight guide vanes are parallel to each other, with a distance of 0.3m between them. The length of each straight guide vane is 1.2m, and its height is 0.1m. The area between the two straight guide vanes is the non-point source pollution control zone; that is, in this embodiment, a parallelogram-shaped non-point source pollution control zone is set up on the simulated riverbank slope.

[0052] Several discretely distributed filling pits were excavated on the slope of the non-point source pollution control area. These pits were evenly distributed across the slope, and their outlines were approximately circular with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounted for 20% of the slope area of ​​the non-point source pollution control area. Environmental functional materials were wrapped in stainless steel mesh to form filling bags. These bags were placed in the filling pits and secured with soil and gravel, protruding approximately 2-5cm from the slope surface. A stainless steel grating was then placed over the filling bags and fixed to the slope with cement to increase their stability. The grating had an openable and closable replacement port for easy replacement of the filling bags.

[0053] The stainless steel mesh has a pore size of no more than 20 μm. The environmental functional material is a mixture of biochar-based functional material and granular sodium persulfate-loaded polymer slow-release material. The sodium persulfate content in the environmental functional material is 10 wt%.

[0054] (4) Non-point source pollution control

[0055] Atrazine was dissolved in tap water to prepare a 1 μmol / L solution, which was used as the simulated wastewater. The simulated wastewater was continuously introduced into the non-point source pollution treatment zone (at the upper end of the zone) at a flow rate of 5 mL / min. During its flow through the zone, the simulated wastewater came into contact with environmental functional materials, which oxidized, degraded, and adsorbed the pollutants in the simulated wastewater, thus removing them.

[0056] Once the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the non-point source pollution treatment zone) to test the concentration of atrazine and calculate the atrazine removal rate. The results showed that the removal rate of atrazine was 78.3%.

[0057] Example 2

[0058] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0059] (1) Preparation of biochar-based functional materials

[0060] Using straw as a precursor for biochar, the straw was calcined at 500℃ in air for 2 hours to obtain biochar. The biochar, sodium fluoride, ferric nitrate, and copper nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, sodium fluoride, ferric nitrate, and copper nitrate were 50 wt%, 25 wt%, 12.5 wt%, and 12.5 wt%, respectively. The reaction precursor was calcined at 500℃ in air for 2 hours to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0061] (2) Constructing a simulated riverbank slope

[0062] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 0° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0063] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0064] like Figure 2 As shown, two identical polygonal guide vanes are installed on a simulated riverbank slope. The upper and lower ends of the polygonal guide vanes connect to the top and bottom of the slope, respectively. Each polygonal guide vane consists of several bent segments, each 40–50 cm long, with an angle of 30–60° between adjacent segments. The height of the polygonal guide vanes is perpendicular to the slope surface. The two polygonal guide vanes are parallel to each other, with a distance of 0.3 m between them. The total length of the polygonal guide vanes is 2.4 m, and their height is 0.1 m. The area between the two polygonal guide vanes is designated as a non-point source pollution control zone.

[0065] On the slope of the non-point source pollution control area, several discretely distributed filling pits are excavated. These pits are evenly distributed across the slope, and their outlines are approximately circular with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounts for 20% of the slope area of ​​the non-point source pollution control area. Environmental functional materials are wrapped in stainless steel mesh to form filling bags. These bags are placed in the filling pits and secured with soil and gravel, protruding approximately 2-5cm from the slope surface. A stainless steel grating is then placed over the filling bags and fixed to the slope with cement to increase their stability. The grating has an openable and closable replacement port for easy replacement of the filling bags.

[0066] The stainless steel mesh has a pore size of no more than 20 μm. The environmental functional material is a mixture of biochar-based functional material and granular sodium persulfate-loaded polymer slow-release material. The sodium persulfate content in the environmental functional material is 10 wt%.

[0067] (4) Non-point source pollution control

[0068] Atrazine was dissolved in tap water to prepare a 1 μmol / L solution, which was used as the simulated wastewater. The simulated wastewater was continuously introduced into the non-point source pollution treatment zone (at the upper end of the zone) at a flow rate of 5 mL / min. During its flow through the zone, the simulated wastewater came into contact with environmental functional materials, which oxidized, degraded, and adsorbed the pollutants in the simulated wastewater, thus removing them.

[0069] Once the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet (lower end) of the treatment zone to test the atrazine concentration and calculate the atrazine removal rate. The results showed that the atrazine removal rate was 95.2%. After one month of continuous operation, water samples were taken from the outlet (lower end) of the treatment zone for testing, and the results showed that the atrazine removal rate remained at 90%–95%. This demonstrates that the method described in this invention has good long-term operational stability.

[0070] Comparative Example 1

[0071] The operation of this comparative example is basically the same as that of Example 2, except for the operation of step (3). The specific operation of step (3) in this example is as follows:

[0072] Two identical straight guide vanes are installed on the simulated riverbank slope. The upper and lower ends of the guide vanes connect to the top and bottom of the slope, respectively. The height of the guide vanes is perpendicular to the slope surface, and the angle between the length of the guide vanes and the bottom (the boundary between the slope and the water surface) is 90°. The two guide vanes are parallel to each other, 0.3m apart, 0.6m long, and 0.1m high. The area between the two guide vanes is designated as a non-point source pollution control zone.

[0073] On the slope of the non-point source pollution control area, several discretely distributed filling pits are excavated. These pits are evenly distributed across the slope, and their outlines are approximately circular with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounts for 20% of the slope area of ​​the non-point source pollution control area. Environmental functional materials are wrapped in stainless steel mesh to form filling bags. These bags are placed in the filling pits and secured with soil and gravel, protruding approximately 2-5cm from the slope surface. A stainless steel grating is then placed over the filling bags and fixed to the slope with cement to increase their stability. The grating has an openable and closable replacement port for easy replacement of the filling bags.

[0074] The stainless steel mesh has a pore size of no more than 20 μm. The environmental functional material is a mixture of biochar-based functional material and granular sodium persulfate-loaded polymer slow-release material. The sodium persulfate content in the environmental functional material is 10 wt%.

[0075] In this comparative example, after the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a steady state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the non-point source pollution treatment zone) to test the concentration of atrazine and calculate the atrazine removal rate. The results showed that the removal rate of atrazine was 38.7%.

[0076] As shown in Examples 1 and 2 and Comparative Example 1, with the increase of the guide plate length, the residence time of simulated wastewater in the non-point source pollution treatment area increases, the total contact time between simulated wastewater and environmental functional materials increases, and the removal rate of atrazine is effectively improved. In practical applications, the removal effect of pollutants can be enhanced by extending the length of the guide plate.

[0077] Comparative Example 2

[0078] The operation of this comparative example is basically the same as that of Example 2, except for the operation of step (1). The specific operation of step (1) in this example is as follows:

[0079] Using straw as a precursor for biochar, the straw was calcined at 500℃ in air for 2 hours to obtain biochar. The biochar, ferric nitrate, and copper nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, ferric nitrate, and copper nitrate were 50 wt%, 25 wt%, and 25 wt%, respectively. The reaction precursor was calcined at 500℃ in air for 2 hours to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0080] In this comparative example, after the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a steady state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the non-point source pollution treatment zone) to test the concentration of atrazine and calculate the atrazine removal rate. The results showed that the removal rate of atrazine was 53.3%.

[0081] As can be seen from Example 2 and Comparative Example 2, if the non-metallic element fluorine is not introduced for modification during the preparation of the biochar-based functional material, the removal effect of atrazine is poor when the prepared biochar-based functional material is used in combination with sodium persulfate. This is mainly because the introduction of the non-metallic element fluorine can, on the one hand, change the functional group composition of the surface of the biochar-based functional material and improve its adsorption performance, and on the other hand, change the electronic structure of the metal active center and enhance the catalytic oxidation performance of the biochar-based functional material.

[0082] Comparative Example 3

[0083] The operation of this comparative example is basically the same as that of Example 2, except that the only difference is that in this comparative example, bio-carbon-based functional materials are directly used as environmental functional materials, that is, the environmental functional materials do not contain sodium persulfate.

[0084] In this comparative example, after the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a steady state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the non-point source pollution treatment zone) to test the concentration of atrazine and calculate the atrazine removal rate. The results showed that the removal rate of atrazine was 20.6%.

[0085] As can be seen from Example 2 and Comparative Example 3, the combined use of sodium persulfate and biochar-based functional materials can significantly enhance the removal effect of atrazine, a recalcitrant organic compound.

[0086] Example 3

[0087] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0088] (1) Preparation of biochar-based functional materials

[0089] Using pig manure as a precursor for biochar, the pig manure was calcined at 400℃ in air for 2 hours to obtain biochar. The biochar, thiocyanate, and nickel nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, thiocyanate, and nickel nitrate were 83.4 wt%, 8.3 wt%, and 8.3 wt%, respectively. The reaction precursor was calcined at 1000℃ in air for 1 hour to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0090] (2) Constructing a simulated riverbank slope

[0091] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 30° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0092] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0093] like Figure 3 As shown, two identical curved guide vanes are installed on the simulated riverbank slope. The upper and lower ends of the curved guide vanes connect to the top and bottom of the slope, respectively. The height direction of the curved guide vanes is perpendicular to the slope surface. The two curved guide vanes are parallel to each other, with a distance of 0.3m between them. The total length of the curved guide vanes is 2.6m, and the height is 0.1m. The area between the two curved guide vanes is the non-point source pollution control zone.

[0094] On the slope of the non-point source pollution control area, several discretely distributed filling pits are excavated. Each filling pit is evenly distributed on the slope, and its outline on the slope is basically a circle with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounts for 40% of the slope area of ​​the non-point source pollution control area. Environmental functional materials are wrapped in stainless steel mesh to form filling bags. The filling bags are placed in each filling pit and fixed in the filling pit with soil and gravel. After fixing, the filling bags protrude about 2-5cm from the slope surface.

[0095] The stainless steel mesh has a pore size of no more than 20 μm, and the environmental functional material is composed of a thorough mixture of biochar-based functional material and calcium peroxide particles, with the calcium peroxide particles comprising 20 wt%.

[0096] (4) Non-point source pollution control

[0097] Ciprofloxacin was dissolved in tap water to prepare a ciprofloxacin concentration of 1 mg / L, which was used as the simulated wastewater. The simulated wastewater was continuously introduced into the non-point source pollution treatment zone from the inlet (upper end of the non-point source pollution treatment zone) at a flow rate of 8 mL / min. During the flow of the simulated wastewater through the non-point source pollution treatment zone, it came into contact with environmental functional materials. The environmental functional materials oxidized, degraded, and adsorbed the pollutants in the simulated wastewater, thereby removing the pollutants.

[0098] Once the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet (lower end) of the treatment zone to test the concentration of ciprofloxacin and calculate the removal rate. The results showed a removal rate of 90.1% for ciprofloxacin. After one month of continuous operation, water samples were taken from the outlet (lower end) of the treatment zone for testing, and the results showed that the removal rate of ciprofloxacin remained at 85%–90%. This demonstrates that the method described in this invention has good long-term operational stability.

[0099] Example 4

[0100] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0101] (1) Preparation of biochar-based functional materials

[0102] Using pig manure as a precursor for biochar, the pig manure was calcined at 500℃ in air for 2 hours to obtain biochar. The biochar, thiocyanate, and nickel nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, thiocyanate, and cobalt nitrate were 50 wt%, 20 wt%, and 30 wt%, respectively. The reaction precursor was calcined at 1300℃ in air for 1 hour to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0103] (2) Constructing a simulated riverbank slope

[0104] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 30° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0105] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0106] like Figure 3As shown, two identical curved guide vanes are installed on the simulated riverbank slope. The upper and lower ends of the curved guide vanes connect to the top and bottom of the slope, respectively. The height direction of the curved guide vanes is perpendicular to the slope surface. The two curved guide vanes are parallel to each other, with a distance of 0.3m between them. The total length of the curved guide vanes is 2.6m, and the height is 0.1m. The area between the two curved guide vanes is the non-point source pollution control zone.

[0107] On the slope of the non-point source pollution control area, several discretely distributed filling pits were excavated. These pits were evenly distributed across the slope, and their outlines were generally circular with a diameter of 0.1m. The total area of ​​all the filling pits on the slope accounted for 40% of the slope area of ​​the non-point source pollution control area. Biochar-based functional materials were wrapped in stainless steel mesh to form filling bags. These bags were placed in the filling pits and secured with soil and gravel, resulting in the bags protruding approximately 2–5 cm from the slope surface.

[0108] The aperture of the stainless steel mesh does not exceed 20 μm.

[0109] (4) Non-point source pollution control

[0110] Ciprofloxacin was dissolved in tap water to prepare a ciprofloxacin concentration of 2 mg / L. This solution was used as simulated wastewater, and peracetic acid was added to the simulated wastewater until the concentration of peracetic acid in the simulated wastewater was 0.05 wt%. The simulated wastewater containing peracetic acid was continuously introduced into the non-point source pollution treatment zone at a flow rate of 5 mL / min from the inlet (upper end of the non-point source pollution treatment zone). During the flow of the simulated wastewater through the non-point source pollution treatment zone, it came into contact with environmental functional materials. The environmental functional materials oxidized, degraded, and adsorbed the pollutants in the simulated wastewater, thereby removing the pollutants from the simulated wastewater.

[0111] After the simulated wastewater flow rate in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the zone) to test the concentration of ciprofloxacin and calculate the ciprofloxacin removal rate. The results showed that the removal rate of ciprofloxacin was 95.4%. After one month of continuous operation, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the zone) for testing, and the results showed that the removal rate of ciprofloxacin remained at 90%–95%.

[0112] Example 5

[0113] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0114] (1) Preparation of biochar-based functional materials

[0115] Using corn cobs as a biochar precursor, the corn cobs were calcined at 1000℃ in air for 1 hour to obtain biochar. The biochar, oxalic acid, and cobalt nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, oxalic acid, and cobalt nitrate were 87 wt%, 8.7 wt%, and 4.3 wt%, respectively. The reaction precursor was calcined at 400℃ in air for 4 hours to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0116] (2) Constructing a simulated riverbank slope

[0117] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 30° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0118] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0119] like Figure 2 As shown, two identical polygonal guide vanes are installed on a simulated riverbank slope. The upper and lower ends of the polygonal guide vanes connect to the top and bottom of the slope, respectively. Each polygonal guide vane consists of several bent segments, each 40–50 cm long, with an angle of 30–60° between adjacent segments. The height of the polygonal guide vanes is perpendicular to the slope surface. The two polygonal guide vanes are parallel to each other, with a distance of 0.3 m between them. The total length of the polygonal guide vanes is 2.4 m, and their height is 0.1 m. The area between the two polygonal guide vanes is designated as a non-point source pollution control zone.

[0120] On the slope of the non-point source pollution control area, several discretely distributed filling pits are excavated. These pits are evenly distributed across the slope, and their outlines are approximately circular with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounts for 10% of the slope area of ​​the non-point source pollution control area. Environmental functional materials are wrapped in stainless steel mesh to form filling bags. These bags are placed in the filling pits and secured with soil and gravel, protruding approximately 2-5cm from the slope surface. A stainless steel grating is then placed over the filling bags and fixed to the slope with cement to increase their stability. The grating has an openable and closable replacement port for easy replacement of the filling bags.

[0121] The aperture of the stainless steel mesh does not exceed 20 μm.

[0122] (4) Non-point source pollution control

[0123] A solution with a hexavalent chromium concentration of 5 mmol / L was used as simulated wastewater. The simulated wastewater was continuously introduced into the non-point source pollution treatment zone at a flow rate of 10 mL / min from the inlet (upper end of the non-point source pollution treatment zone). During the flow of the simulated wastewater through the non-point source pollution treatment zone, it came into contact with environmental functional materials. The environmental functional materials reduced, degraded, and adsorbed the pollutants in the simulated wastewater, thereby removing the pollutants.

[0124] Once the flow rate of the simulated wastewater in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the zone) to test the concentration of hexavalent chromium and calculate its removal rate. The results showed that the removal rate of hexavalent chromium was 55.7%. This embodiment demonstrates that for pollutants that do not require oxidative degradation, simply adding biochar-based functional materials to the packing material can achieve satisfactory pollutant removal rates through the adsorption and reduction effects of the biochar-based functional materials.

[0125] Example 6

[0126] This embodiment details the method for non-point source pollution control using riverbank slopes according to the present invention. Specifically, it involves constructing a simulated riverbank slope in a laboratory to control non-point source pollution. The steps are as follows:

[0127] (1) Preparation of biochar-based functional materials

[0128] Using corn cobs as a biochar precursor, the corn cobs were calcined at 500℃ in air for 2 hours to obtain biochar. The biochar, oxalic acid, and cobalt nitrate were thoroughly mixed to obtain a reaction precursor, in which the contents of biochar, oxalic acid, and cobalt nitrate were 90 wt%, 6 wt%, and 4 wt%, respectively. The reaction precursor was calcined at 600℃ in air for 2 hours to obtain biochar-based functional materials. These materials were then pulverized and sieved to obtain biochar-based functional materials with a particle size between 20 and 50 μm.

[0129] (2) Constructing a simulated riverbank slope

[0130] The dimensions of the simulated riverbank slope are determined based on the dimensions of the actual riverbank slope to be treated for non-point source pollution. The actual riverbank slope has an inclination angle (the angle between the slope surface and the horizontal plane) of 30° and a height (the vertical distance between the top and bottom of the slope) of 6m. The ratio of the simulated riverbank slope dimensions to the actual riverbank slope dimensions is controlled at 1:20. That is, the simulated riverbank slope has an inclination angle of 30° and a height of 0.3m.

[0131] (3) Set up non-point source pollution control zones on simulated riverbank slopes.

[0132] like Figure 2 As shown, two identical polygonal guide vanes are installed on a simulated riverbank slope. The upper and lower ends of the polygonal guide vanes connect to the top and bottom of the slope, respectively. Each polygonal guide vane consists of several bent segments, each 40–50 cm long, with an angle of 30–60° between adjacent segments. The height of the polygonal guide vanes is perpendicular to the slope surface. The two polygonal guide vanes are parallel to each other, with a distance of 0.3 m between them. The total length of the polygonal guide vanes is 2.4 m, and their height is 0.1 m. The area between the two polygonal guide vanes is designated as a non-point source pollution control zone.

[0133] On the slope of the non-point source pollution control area, several discretely distributed filling pits are excavated. These pits are evenly distributed across the slope, and their outlines are approximately circular with a diameter of 0.1m. The total area of ​​all filling pits on the slope accounts for 80% of the slope area of ​​the non-point source pollution control area. Biochar-based functional materials are wrapped in stainless steel mesh to form filling bags. These bags are placed in the filling pits and secured with soil and gravel, protruding approximately 2-5cm from the slope surface. A stainless steel grating is then placed over the filling bags and fixed to the slope with cement to increase their stability. The grating has an openable and closable replacement port for easy replacement of the filling bags.

[0134] The aperture of the stainless steel mesh does not exceed 20 μm.

[0135] (4) Non-point source pollution control

[0136] Potassium nitrate and phenol were dissolved in tap water to prepare solutions with potassium nitrate concentrations of 8 mg / L and phenol concentrations of 1 mg / L, respectively. These solutions were used as simulated wastewater. The simulated wastewater was continuously introduced into the non-point source pollution treatment zone (at the upper end of the zone) at a flow rate of 4 mL / min. As the simulated wastewater flowed through the zone, it came into contact with biochar-based functional materials. The biochar-based functional materials adsorbed and removed the pollutants from the simulated wastewater.

[0137] Once the flow velocity of the simulated wastewater in the non-point source pollution treatment zone reached a stable state, water samples were taken from the outlet of the non-point source pollution treatment zone (the lower end of the zone) to test the concentrations of potassium nitrate and phenol and calculate their removal rates. The results showed that the removal rate for potassium nitrate was 31.3%, and the removal rate for phenol was 62.4%. This embodiment demonstrates that for certain pollutants, especially those with low concentrations, adding biochar-based functional materials only to the packing material can achieve satisfactory pollutant removal rates through the adsorption effect of the biochar-based functional materials.

[0138] Those skilled in the art will recognize that the embodiments described herein are intended to help them understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for controlling non-point source pollution using riverbank slopes, characterized in that, Includes the following steps: (1) Preparation of biochar-based functional materials Biochar precursors are calcined at 200-1500 °C to obtain biochar. Biochar, non-metallic element precursors and metal salts are thoroughly mixed to obtain reaction precursors. The reaction precursors are calcined at 200-1500 °C to obtain biochar-based functional materials. In the reaction precursor, the contents of biochar, non-metallic element precursor, and metal salt are 50 wt%~90 wt%, 4 wt%~20 wt%, and 6 wt%~30 wt%, respectively; the non-metallic element precursor is at least one selected from fluoride salt, sulfide salt, nitrate, ammonium salt, phosphate, pyrophosphate, oxalic acid, and thiocyanate; the metal salt is at least one selected from iron salt, copper salt, cobalt salt, and nickel salt. (2) At least two guide plates shall be installed on the riverbank where non-point source pollution wastewater flows into the river. The upper and lower ends of the guide plates shall connect to the top and bottom of the slope, respectively. The area between the guide plates shall be the non-point source pollution treatment area. The length of the guide plate shall be at least twice the distance between the top and bottom of the slope, and the distance between adjacent guide plates shall be 1 to 5 m. Several arrayed filling pits are dug on the slope of the non-point source pollution control area. The total area of ​​each filling pit on the slope accounts for 5% to 80% of the slope area of ​​the non-point source pollution control area. Biochar-based functional materials or environmental functional materials are wrapped in a mesh with micron-sized pores to form filling bags. The filling bags are fixed in each filling pit so that the filling bags protrude from the slope. The environmental functional material is formed by fully mixing biochar-based functional materials and solid oxidants. The solid oxidants are solid oxidants that are insoluble or slightly soluble in water, or water-soluble solid oxidants loaded in slow-release materials. (3) When the packing bag in step (2) does not contain a solid oxidant, a liquid oxidant is added to the non-point source pollution wastewater upstream of the non-point source pollution treatment zone to form non-point source pollution wastewater containing oxidant materials. The liquid oxidant is a liquid oxidant material, an aqueous solution of liquid oxidant material, or an aqueous solution of solid oxidant material. The non-point source pollution wastewater containing oxidant materials is introduced into the non-point source pollution treatment zone. The wastewater comes into contact with biochar-based functional materials during the flow through the non-point source pollution treatment zone. The biochar-based functional materials and oxidant materials degrade and adsorb the pollutants in the wastewater, remove the pollutants in the wastewater, and achieve the treatment of non-point source pollution wastewater. When the packing bag in step (2) contains a solid oxidant, the non-point source pollution wastewater is introduced into the non-point source pollution treatment area. The wastewater comes into contact with the environmental functional materials during the process of flowing through the non-point source pollution treatment area. The environmental functional materials degrade and adsorb the pollutants in the wastewater, remove the pollutants in the wastewater, and achieve the treatment of non-point source pollution wastewater. The oxidizing material is calcium peroxide, persulfate, potassium permanganate, potassium dichromate, hydrogen peroxide, or peracetic acid.

2. The method for non-point source pollution control using riverbank slopes according to claim 1, characterized in that, The content of solid oxide materials in environmental functional materials is 5 wt% to 30 wt%.

3. The method for non-point source pollution control using riverbank slopes according to claim 1, characterized in that, When step (3) requires adding a liquid oxidant to the non-point source pollution wastewater upstream of the non-point source pollution treatment area to form non-point source pollution wastewater containing oxidants, the concentration of the oxidants in the resulting non-point source pollution wastewater containing oxidants should be controlled to be 10%. -7 wt%~1 wt%.

4. The method for non-point source pollution control using riverbank slopes according to any one of claims 1 to 3, characterized in that, After fixing the packing bags in each packing pit, cover the packing bags with a grid mesh.

5. The method for non-point source pollution control using riverbank slopes according to claim 4, characterized in that, The grid cover is detachably fixed to the slope of the non-point source pollution control area, or a filler bag replacement port is provided on the grid cover, which can be opened and closed.

6. The method for non-point source pollution control using riverbank slopes according to any one of claims 1 to 3, characterized in that, The guide vane is in the form of a straight line, a broken line, or a curve, or a combination of two or more of the following: a straight line, a broken line, and a curve.

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