A method for purifying organic polluted water bodies by a constructed wetland with plants

Abstract

A method for purifying organic-polluted water bodies by a constructed wetland with plants, comprising the following steps: pumping the organic-polluted water body and the effluent of the constructed wetland with plants into a pre-pond in a volume ratio of 1:1-10 through a metering pump for uniform mixing, and then adopting an intermittent water inlet mode, pumping the water body in the pre-pond into the constructed wetland with plants through a sewage pump at a frequency of 1-3 times each in the morning and evening every day, with the water inflow being 10-100 L and the hydraulic retention time being 5-20 days; the constructed wetland with plants is composed of several treatment units connected in series. The method for purifying organic-polluted water bodies by the constructed wetland with plants of the present invention reduces the organic pollutants in the organic-polluted water body through the constructed wetland with plants to improve the water quality. The constructed wetland with plants for net treatment adopts a multi-stage subsurface flow treatment unit. Inside each treatment unit, wetland fillers and modified water purification fillers are filled from top to bottom. The cooperation of the wetland fillers, modified water purification fillers and plants can effectively purify the organic-polluted water body, with excellent purification effect and wide application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial wetland purification, and particularly relates to a method for purifying organic polluted water bodies by a plant artificial wetland. Background Art

[0002] There are various methods for treating water pollution by applying the principles and methods of ecology, and among them, the artificial wetland technology is an important part. Compared with other water pollution treatment methods, artificial wetlands have many advantages, such as low construction cost, no energy consumption required, low operation cost, friendly to the ecological environment, and easy to develop. Chinese Patent Application No. CN202210121085.3 discloses an artificial wetland sewage purification device and its sewage treatment method. The artificial wetland includes an upper treatment area and a lower treatment area; a waterproof layer is provided between the upper treatment area and the lower treatment area; the upper treatment area includes a water-based plant purification area and a planktonic microorganism purification area that are interconnected; multiple water-based plant planting boxes are arranged in the water-based plant purification area; a porous attachment layer is arranged in the planktonic microorganism purification area; the lower treatment area includes a physical filtration purification area. The upper treatment area mainly relies on the growth and reproduction of water-based plants and microorganisms to absorb organic pollutants and nitrogen and phosphorus nutrients in the sewage, while the lower treatment area filters insoluble impurities in the sewage through physical filtration.

[0003] An artificial wetland is a type of wetland system designed, constructed, and operated by humans based on the research, induction, and summary of natural wetlands, and is mainly composed of main components such as substrates, plants, and microorganisms. The organic pollution of water bodies mainly refers to the pollution caused by the discharge of wastewater containing a large amount of organic matter from urban sewage, the food industry, the paper industry, etc. Treating the organic pollution of water bodies by an artificial wetland is a systematic project, which is the result of the joint participation of elements such as the internal substrates of the ecological project, plants, and wetland microorganisms.

[0004] Chinese Patent Application No. CN202110535694.9 discloses a method for treating organic matter in an artificial wetland. By artificially creating wetland partition ponds for experiments on wetland treatment of organic matter, the purpose is to improve the efficiency of low-temperature microbial bacteria in decomposing organic matter. At the same time, in the power energy supply part, solar energy storage is adopted, which has a good environmental protection and energy-saving effect.

[0005] The purpose of the present invention is to develop a new plant artificial wetland and a method for purifying organic polluted water bodies using the plant artificial wetland, and to improve the purification effect of the artificial wetland on organic polluted water bodies by optimizing the construction of the plant artificial wetland (plant selection, substrate selection) and the operation mode of the plant artificial wetland. Summary of the Invention

[0006] Objective of the Invention: To overcome the above deficiencies, the objective of the present invention is to provide a method for purifying organic polluted water bodies by a constructed wetland with plants, which is simple and controllable. The method reduces organic pollutants in the organic polluted water bodies through the constructed wetland with plants, improves water quality. The constructed wetland with plants for purification treatment adopts a multi-stage subsurface flow treatment unit. Inside each treatment unit, wetland fillers and modified water purification fillers are filled from top to bottom. The combination of wetland fillers, modified water purification fillers and plants can effectively purify the organic polluted water bodies, with excellent purification effect, good universality, great application value and broad application prospects.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for purifying organic polluted water bodies by a constructed wetland with plants, including the following steps: Pump the organic polluted water bodies and the effluent of the constructed wetland with plants into the pre-pond according to a volume ratio of 1:1 - 10 by a metering pump and mix them evenly. Then, adopt the intermittent water inlet mode, and pump the water in the pre-pond into the constructed wetland with plants by a sewage pump at a frequency of 1 - 3 times in the morning and evening every day, with the water inflow of 10 - 100 L and the hydraulic retention time of 5 - 20 days.

[0009] Among them, the constructed wetland with plants is composed of several treatment units connected in series. The heights of several treatment units decrease successively, and the height difference between adjacent treatment units is 5 - 50 cm. Each treatment unit includes:

[0010] Treatment pond;

[0011] Wetland fillers, with wetland fillers filled in the upper part of the treatment pond;

[0012] Modified water purification fillers, with modified water purification fillers filled in the lower part of the treatment pond; The modified water purification fillers include the following raw materials: coarse aggregate 1000 - 1500 kg / m 3 、fine aggregate 100 - 200 kg / m 3 、cement 100 - 200 kg / m 3 、modified degradation agent 100 - 150 kg / m 3 、water 80 - 100 kg / m 3 、hydrotalcite 1 - 5 kg / m 3 、admixture 1 - 5 L / m 3 ;

[0013] Plants, with the plants planted on the wetland fillers in each treatment pond at a planting density of 20 - 100 plants·m -2 , and the plants include summer plants and winter plants;

[0014] Inlet water distribution pipeline system, with the inlet water distribution pipeline system arranged on the top of the wetland fillers;

[0015] An effluent collection pipeline system is arranged at the bottom of the ecological concrete filler; the water outlet of the effluent collection pipeline system is connected to the water inlet of the water distribution pipeline system of the next-stage treatment unit through a pipeline, and the water inlet of the water distribution pipeline system is connected to the water outlet of the previous-stage treatment unit through a pipeline.

[0016] In the method for purifying organic polluted water bodies by the plant constructed wetland of the present invention, the plant constructed wetland is used to reduce the organic pollutants in the organic polluted water bodies and improve the water quality. The plant constructed wetland purification treatment adopts multi-stage subsurface flow treatment units, and the height difference between each stage of treatment unit is 5-50 cm, so that the water body flows to the next-stage treatment unit under the action of gravity. Each treatment unit is planted with plants, and the plants are a mixture of summer plants and winter plants. Compared with the constructed wetland planted with a single plant, the biodiversity is better, and the purification effect of the polluted water body and the landscape effect are also better. Plants grow in the constructed wetland throughout the four seasons. By respectively arranging a water inlet distribution pipeline system and an effluent collection pipeline system at the top and bottom of the treatment pool, the uniformity of the inlet and outlet water of the constructed wetland can be improved.

[0017] Inside the treatment unit, wetland filler and modified water purification filler are filled from top to bottom. The wetland filler is used not only for planting plants to promote the growth of microorganisms and plants, but also as the first layer to purify and improve the treatment effect of organic polluted water bodies and increase the treatment load of the treatment unit; the modified water purification filler is used as the second layer of purification, has better water purification ability, good water permeability and strong adsorption ability. The coarse aggregate, fine aggregate and cement are compounded as the main body, and the hydrotalcite is added to improve the overall compressive strength and TP removal effect. By adding a modified degradation agent, the organic pollutants in the organic polluted water body are removed through mechanisms such as adsorption coprecipitation, surface complexation, reduction and oxidation, so that the organic pollutants are finally degraded into intermediate small molecules or completely mineralized into water and carbon dioxide. An admixture is added to improve the overall compressive strength, water permeability and porosity.

[0018] Furthermore, in the method for purifying organic polluted water bodies by the plant constructed wetland described above, the wetland filler is selected from at least one of calcined clay, biochar, vermiculite, zeolite, volcanic rock, perlite, aerated concrete block.

[0019] Preferably, the wetland filler adopts an aerated concrete block, which is mainly composed of fly ash, lime and clay materials, has the characteristics of porous, light weight and not floating on the water surface, and has a relatively large specific surface area, which can provide a relatively large attachable growth area for microorganisms, is beneficial to the growth of microorganisms, and has a good adsorption effect on the organic pollutants in the organic polluted water body.

[0020] Further, in the method for purifying organic-polluted water body by the above plant constructed wetland, the coarse aggregate is selected from at least one of natural gravel with a particle size range of 5 - 16.5 mm, 10 - 20 mm, and 16.5 - 31.5 mm; the fine aggregate is selected from at least one of manufactured sand, natural sand, and tailings sand with a particle size range of 50 - 200 μm; the cement is selected from P·O 42.5 grade cement; the hydrotalcite is selected from carbonate-type magnesium-aluminum hydrotalcite with a particle size range of 0.5 - 2 μm; and the admixture is selected from ZS-2 type vegetation admixture.

[0021] By selecting coarse aggregates, fine aggregates, and cement with different particle size ranges for compounding, the porosity of the wetland filler can be increased, which is beneficial to the removal effect of TP and TN.

[0022] Further, in the method for purifying organic-polluted water body by the above plant constructed wetland, the preparation of the modified water purification filler includes the following steps: After uniformly stirring and mixing the coarse aggregate, fine aggregate, cement, water, hydrotalcite, modified degradation agent, and ZS-2 type vegetation admixture, a cube is made according to the manufacturing process of mold loading, manual vibration, compaction, and demolding after standing for 24 h, and the cube is stacked at the lower part of the treatment tank to obtain the modified water purification filler.

[0023] Further, in the method for purifying organic-polluted water body by the above plant constructed wetland, the preparation of the modified degradation agent includes the following steps: Prepare a melamine solution with a mass fraction of 0.05 - 0.1% and a trimesic acid solution with a mass fraction of 0.1 - 0.2% respectively. Heat the melamine solution and the trimesic acid solution to 60 - 80 °C, then mix equal volumes of the melamine solution and the trimesic acid solution, let it stand at room temperature until cooled, and then pour off the supernatant. Centrifuge and collect the white precipitate; Wash the white precipitate thoroughly with deionized water and dry it in a vacuum drying oven at 60 - 80 °C to obtain the precursor; Grind the precursor, ferric chloride, and anhydrous zinc chloride into a uniform mixed powder at room temperature according to a mass ratio of 6 - 8:1 - 2:0.5 - 1. Then, place the mixed powder in a saturated N2 atmosphere and heat-treat it in a tubular furnace at 600 - 1000 °C for 3 - 4 h. After removal, ultrasonically treat it in hydrochloric acid with a concentration of 1 - 3 mol / L for 0.5 - 2 h, wash the white precipitate thoroughly with deionized water, and dry it in a vacuum drying oven at 60 - 80 °C to obtain the modified degradation agent.

[0024] The modified degradation agent uses a precursor as a hydrogen-bonded organic framework, then incorporates Fe active substances into the precursor, and forms topological defects through high-temperature evaporation to obtain a modified degradation agent with a chemical complexation and graphene-like structure. The modified degradation agent removes organic pollutants in organic polluted water through mechanisms such as adsorption coprecipitation, surface complexation, reduction, and oxidation. In addition, the hydrogen-bonded organic framework has a hierarchical pore structure and a high specific surface area, and has a very high adsorption capacity for organic pollutants in organic polluted water. After heat treatment, the stability of the modified degradation agent is enhanced through acidification treatment.

[0025] Furthermore, in the method for purifying organic polluted water by the above-mentioned constructed wetland, the summer plants are selected from at least one of canna, reed, cyperus alternifolius, and alligator weed.

[0026] Furthermore, in the method for purifying organic polluted water by the above-mentioned constructed wetland, the winter plants are selected from at least one of dock, cardamine lyrata, iris germanica, and juncus effusus.

[0027] Furthermore, in the method for purifying organic polluted water by the above-mentioned constructed wetland, the influent water distribution pipe system is composed of several water distribution branch pipes, and each water distribution branch pipe is evenly staggered and laid flat on the cross-section of the wetland filler in the area near the top of the treatment tank.

[0028] Furthermore, in the method for purifying organic polluted water by the above-mentioned constructed wetland, the effluent water collection pipe system is composed of several water collection branch pipes, and each water collection branch pipe is evenly staggered and laid flat on the cross-section of the modified water purification filler in the area near the bottom of the treatment tank.

[0029] Compared with the prior art, the present invention has the following beneficial effects: The method for purifying organic polluted water by the constructed wetland described in the present invention is simple and controllable. The constructed wetland composed of multi-stage subsurface flow treatment units adsorbs, degrades, and reduces organic pollutants in organic polluted water, achieving the effect of improving water quality. Each treatment unit is planted with plants, and the plants are a mixture of summer plants and winter plants. Compared with the constructed wetland planted with a single plant, the biodiversity is better, and the purification effect of polluted water and the landscape effect are also better. Inside the treatment unit, wetland filler and modified water purification filler are filled from top to bottom. The wetland filler is used to plant plants, promote the growth of microorganisms and plants, and can also be used as the first layer of purification to improve the treatment effect of organic polluted water and increase the treatment load of the treatment unit. The modified water purification filler is used as the second layer of purification, has better water purification ability, good water permeability, and strong adsorption ability. The coarse aggregate, fine aggregate, and cement are compounded as the main body, and the overall compressive strength and TP removal effect are improved by adding hydrotalcite. By adding a modified degradation agent, the adsorption, surface cracking, and hydrolysis of organic pollutants in organic polluted water are driven by mechanisms such as adsorption coprecipitation, surface complexation, reduction, and oxidation. Description of the Drawings

[0030] Figure 1 Schematic connection diagram of the plant constructed wetland of the present invention;

[0031] Figure 2 Degradation curve graph of organic pollutant solutions of bisphenol A, sulfamethoxazole, 2-chlorophenol, phenytoin, atrazine, ibuprofen, and ciprofloxacin by the modified degradation agent prepared in Example 1 of the present invention;

[0032] In the figure: Plant constructed wetland 1, treatment unit 11, treatment pond 111, wetland filler 112, modified water purification filler 113, influent water distribution pipeline system 114, effluent water collection pipeline system 115, pre-pond 2. Specific implementation manners

[0033] Next, Example 1, Comparative Example 1, Example 2, and Example 3 will be combined with experimental data and appendices Figure 1-2 , and the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] Example 1 provides a modified degradation agent.

[0035] Example 1

[0036] Preparation of the modified degradation agent, including the following contents: Prepare a melamine solution with a mass fraction of 0.75% and a trimesic acid solution with a mass fraction of 0.1% respectively. Heat the melamine solution and the trimesic acid solution to 60°C, then mix equal volumes of the melamine solution and the trimesic acid solution, let it stand at room temperature until cooled, and then pour off the supernatant. Centrifuge to collect the white precipitate; Wash the white precipitate thoroughly with deionized water and dry it in a vacuum drying oven at 60°C to obtain a precursor; Grind the precursor, ferric chloride, and anhydrous zinc chloride into a uniform mixed powder at room temperature according to a mass ratio of 82:14:4. Then, place the mixed powder in a saturated N2 atmosphere and heat-treat it in a tubular furnace at 800°C for 3 h. After removal, ultrasonically treat it in hydrochloric acid with a concentration of 1 mol / L for 1 h. Wash the white precipitate thoroughly with deionized water and dry it in a vacuum drying oven at 70°C to obtain the modified degradation agent.

[0037] The catalytic performance of the prepared modified degrading agent was tested, and the test method was as follows: 100 mg of the modified degrading agent was dispersed into 250 mL of the organic pollutant solution, and the whole process was reacted under constant temperature magnetic stirring at 35 °C. At certain intervals, 1 mL of the liquid was collected, filtered through a PTFE membrane with a pore size of 0.45 μm, and the filtered sample was placed in a sample bottle, and the catalytic performance was analyzed using a TOC analyzer. The test results are shown in the appendix Figure 2 .

[0038] Among them, the organic pollutant solutions were bisphenol A, sulfamethoxazole, 2-chlorophenol, phenytoin, atrazine, ibuprofen, and ciprofloxacin, and the initial concentration of the organic pollutants in each organic pollutant solution was 10 mg L -1 , and the initial pH was about 6.5.

[0039] From the appendix Figure 2 It can be seen that as the reaction time prolonged, the prepared modified degrading agent of the present invention significantly degraded the target organic pollutants. Among them, bisphenol A, ibuprofen, and ciprofloxacin were degraded by nearly 100% within 30 min, 2-chlorophenol was degraded by nearly 100% within 45 min, and sulfamethoxazole, phenytoin, and atrazine were degraded by nearly 100% within 90 min. From the above, it can be obtained that the modified degrading agent has excellent adsorption and degradation effects on organic pollutants in water.

[0040] Example 2 provides a modified water purification filler.

[0041] Example 2

[0042] Preparation of the modified water purification filler, including the following: The modified water purification filler includes the following raw materials: coarse aggregate 1420 kg / m 3 (using natural gravel with a size of 5 - 16.5 mm), fine aggregate 180 kg / m 3 (using natural sand with a size of 50 - 100 μm), P·O 42.5 grade cement 120 kg / m 3 , the modified degrading agent of Example 1 110 kg / m 3 , water 100 kg / m 3 , carbonate-type magnesium-aluminum hydrotalcite with a size of 0.5 - 2 μm 5 kg / m 3 , ZS-2 type vegetation admixture 5 L / m 3 . After the above raw materials were stirred and mixed evenly, they were made into a 150 mm × 150 mm × 150 mm cube of the modified water purification filler according to the production process of mold loading, manual vibration, compaction, and standing for 24 h for demolding.

[0043] According to the relevant content in Article 8 of the "Test Methods for Physical and Mechanical Properties of Ecological Porous Concrete", the porosity of the modified water purification filler cubes prepared after 28 days of curing was measured by the suspension immersion method, and the measured porosity was 30.17%; according to the "Standard Test Method for Mechanical Properties of Ordinary Concrete" (GB / T 50081-2002) and the "Test Methods for Physical and Mechanical Properties of Ecological Porous Concrete", the compressive strength of the modified water purification filler cubes prepared after 28 days of curing was measured by a pressure testing machine, and the measured compressive strength was 10.1 / Mpa. It can be seen from the above that the modified water purification filler prepared by the present invention has appropriate porosity and compressive strength.

[0044] The water purification performance of the modified water purification filler cubes prepared after 28 days of curing was tested. The test method is as follows: Place the modified water purification filler cubes prepared after 28 days of curing in a test bucket, prepare a blank bucket as a control group, pour the raw water to be purified into the test bucket and the blank bucket respectively (9L of raw water is poured into each bucket), then place the test bucket and the blank bucket under the window sill indoors, irradiate with natural light, ventilate for 24 hours, and conduct a static water purification test. After the test starts, collect water samples for water quality detection every 24 hours and continuously monitor for 7 days. Among them, the raw water to be purified is taken from the leachate of a landfill, and its water quality indicators are shown in Table 1. The test results of the static water purification test are shown in Tables 2, 3, and 3.

[0045] Table 1 Water Quality Indicators of the Raw Water to be Purified

[0046] TN / (mg / L) TP / (mg / L) COD / (mg / L) pH 1001.9 5.9 4562.1 8.92

[0047] Table 2 Variation Results of TN Concentration in the Test Bucket with Time in the Static Water Purification Test

[0048]

[0049]

[0050] Table 3 Variation Results of TP Concentration in the Test Bucket with Time in the Static Water Purification Test

[0051] TP / (mg / L) 0d 5.90 1d 4.11 2d 3.52 3d 2.63 4d 2.05 5d 1.64 6d 1.42 7d 1.14

[0052] Table 4 Variation Results of COD Concentration in the Test Bucket with Time in the Static Water Purification Test

[0053]

[0054]

[0055] As can be seen from Tables 2, 3, and 4, the modified water purification filler prepared by the present invention has good removal effects on TN, TP, and COD in organic polluted water bodies. The TN removal rate is 52.3%, the TP removal rate is 80.7%, and the COD removal rate is 75.2%.

[0056] Comparative Example 1, Comparative Example 2, and Example 3 provide a method for purifying organic polluted water bodies by a constructed wetland with plants.

[0057] Comparative Example 1

[0058] As Figure 1 shown, the method for purifying organic polluted water bodies by the constructed wetland with plants includes the following steps: The organic polluted water body and the effluent of the constructed wetland 1 are pumped into the pre - treatment tank 2 at a volume ratio of 1:5 by a metering pump and mixed evenly. Then, in an intermittent water - inlet mode, the water body in the pre - treatment tank 2 is pumped into the constructed wetland 1 by a sewage pump once in the morning and once in the evening every day, with a water inflow of 15 L and a hydraulic retention time of 12 days;

[0059] Among them, the constructed wetland 1 is composed of 4 treatment units 11 connected in series. The 4 treatment units 11 decrease in turn, and the height difference between adjacent treatment units 11 is 15 cm, so that the water body flows to the next - level treatment unit 11 under the action of gravity. Each treatment unit 11 includes:

[0060] Treatment tank 111 (length × width × height: 5 m × 4 m × 3 m);

[0061] Wetland filler 112, and the entire treatment tank 11 is filled with wetland filler 112 (aerated concrete blocks);

[0062] Plants, which are planted in the wetland filler 112 of each treatment tank 111 at a planting density of 50 plants·m -2 The plants are selected as Canna indica, Phragmites australis, Rumex acetosa, and Iris germanica, and the planting ratio of the number of plants is 20:15:5:10;

[0063] Inlet water distribution pipeline system 114, which is composed of several water - distribution branch pipes, and each water - distribution branch pipe is evenly staggered and laid flat on the cross - section of the wetland filler 112 in the area close to the top of the treatment tank 111;

[0064] Outlet water collection pipeline system 115, which is composed of several water - collection branch pipes, and each water - collection branch pipe is evenly staggered and laid flat on the cross - section of the modified water purification filler 113 in the area close to the bottom of the treatment tank 111.

[0065] Example 3

[0066] As Figure 1As shown, the method for purifying organic-polluted water bodies by a constructed wetland for plants includes the following steps: The organic-polluted water body and the effluent of the constructed wetland for plants 1 are pumped into the pre-pond 2 at a volume ratio of 1:5 by a metering pump and mixed evenly. Then, in an intermittent water inlet mode, the water body in the pre-pond 2 is pumped into the constructed wetland for plants 1 by a sewage pump once in the morning and once in the evening every day, with the water inflow being 15 L and the hydraulic retention time being 12 days.

[0067] Among them, the constructed wetland for plants 1 is composed of 4 treatment units 11 connected in series. The 4 treatment units 11 are successively decreasing, and the height difference between adjacent treatment units 11 is 15 cm, so that the water body flows to the next-level treatment unit 11 under the action of gravity. Each treatment unit 11 includes:

[0068] Treatment pond 111 (length × width × height: 5 m × 4 m × 3 m);

[0069] Wetland filler 112. The upper part of the treatment pond 11 is filled with wetland filler 112 (aerated concrete blocks, filled length × width × height: 5 m × 4 m × 2 m);

[0070] Modified water purification filler 113 (made up of cubic modified water purification fillers prepared in Example 2, filled length × width × height: 5 m × 4 m × 1 m);

[0071] Plants are planted in the wetland filler 112 of each treatment pond 111 at a planting density of 50 plants·m -2 The plants selected are Canna indica, Phragmites australis, Rumex acetosa, and Iris germanica, and the planting ratio of the plants is 20:15:5:10;

[0072] Inlet water distribution pipeline system 114. The inlet water distribution pipeline system 114 is composed of several water distribution branch pipes, and each water distribution branch pipe is evenly staggered and laid flat on the cross-section of the wetland filler 112 in the area close to the top of the treatment pond 111;

[0073] Outlet water collection pipeline system 115. The outlet water collection pipeline system 115 is composed of several water collection branch pipes, and each water collection branch pipe is evenly staggered and laid flat on the cross-section of the modified water purification filler 113 in the area close to the bottom of the treatment pond 111.

[0074] The water purification performance of the methods for purifying organic-polluted water bodies by the constructed wetland for plants in Comparative Example 1 and Example 3 was tested. The test method is as follows: After the constructed wetland for plants operates, the return water samples of the constructed wetland for plants are collected once every 24 h for water quality detection, continuously monitored for 7 d, and the average value of 7 days is taken. Among them, the raw water to be purified is taken from the leachate of a certain landfill, and its water quality indicators are shown in Table 1, and the water quality test results are shown in Tables 5, 6, and 7.

[0075] Table 5 Results of the change in TN concentration over time in the water purification tests of Comparative Example 1 and Example 3

[0076] TN / (mg / L) of Comparative Example 1 TN / (mg / L) of Example 3 0d 1001.9 1001.9 7-day average 217.4 118.2

[0077] Table 6 Results of the change in TP concentration over time in the water purification tests of Comparative Example 1 and Example 3

[0078] TP / (mg / L) of Comparative Example 1 TP / (mg / L) of Example 3 0d 5.90 5.90 7-day average 0.85 0.37

[0079] Table 7 Results of the change in COD concentration over time in the water purification tests of Comparative Example 1 and Example 3

[0080] COD / (mg / L) of Comparative Example 1 COD / (mg / L) of Example 3 0d 4562.1 4562.1 7-day average 802.9 451.6

[0081] It can be seen from Tables 5, 6, and 7 that the method of using the constructed wetland with plants in Example 3 to purify organic polluted water bodies has better TN, TP, and COD removal effects on organic polluted water bodies. The TN removal rate is 88.2%, the TP removal rate is 93.7%, and the COD removal rate is 90.1%.

[0082] There are many specific application ways of the present invention, and the above description is only the preferred embodiment of the present invention. It should be noted that the above embodiments are only used to illustrate the present invention and do not limit the protection scope of the present invention. For those of ordinary skill in the art of this technology, several improvements can be made without departing from the principle of the present invention, and these improvements should also be regarded as within the protection scope of the present invention.

Claims

1. A method for purifying organic polluted water bodies by a constructed wetland for plants, characterized in that, It includes the following: The organic polluted water body and the effluent of the constructed wetland with plants (1) are pumped into the pre - treatment tank (2) in a volume ratio of 1:1 - 10 by a metering pump and mixed evenly. Then, in an intermittent water - inlet mode, the water body in the pre - treatment tank (2) is pumped into the constructed wetland with plants (1) by a sewage pump at a frequency of 1 - 3 times each in the morning and evening every day, with the water inflow being 10 - 100 L and the hydraulic retention time being 5 - 20 days. Among them, the constructed wetland with plants (1) is composed of several treatment units (11) connected in series. The heights of several treatment units (11) decrease successively, and the height difference between adjacent treatment units (11) is 5 - 50 cm. Each treatment unit (11) includes: A treatment tank (111); Wetland fillers (112), and the upper part of the treatment tank (111) is filled with wetland fillers (112); Modified water purification filler (113), the lower part of the treatment tank (111) is filled with modified water purification filler (113); the modified water purification filler (113) comprises the following raw materials: coarse aggregate 1000-1500 kg / m 3 , fine aggregate 100-200 kg / m 3 , cement 100-200 kg / m 3 , modified degradation agent 100-150 kg / m 3 , water 80-100 kg / m 3 , hydrotalcite 1-5 kg / m 3 , admixture 1-5 L / m 3 ; Plant, the plant is planted at a planting density of 20 - 100 plants·m -2 on the wetland filler (112) of each treatment pond (111), and the plants include summer plants and winter plants; An influent water - distribution pipeline system (114), and the influent water - distribution pipeline system (114) is arranged on the top of the wetland fillers (112); An effluent water - collection pipeline system (115), and the effluent water - collection pipeline system (115) is arranged at the bottom of the eco - concrete fillers; the outlet of the effluent water - collection pipeline system (115) is connected to the inlet of the influent water - distribution pipeline system (114) of the next - level treatment unit (11) through a pipeline, and the inlet of the influent water - distribution pipeline system (114) is connected to the outlet of the previous - level treatment unit (11) through a pipeline; The preparation of the modified degradation agent includes the following: Prepare a melamine solution with a mass fraction of 0.05 - 0.1% and a trimellitic acid solution with a mass fraction of 0.1 - 0.2% respectively. Heat the melamine solution and the trimellitic acid solution to 60 - 80 °C, then mix equal volumes of the melamine solution and the trimellitic acid solution, place it at room temperature until cooled, and then pour out the supernatant. Centrifuge to collect the white precipitate; Wash the white precipitate thoroughly with deionized water and dry it in a vacuum drying oven at 60 - 80 °C to obtain a precursor; Grind the precursor, ferric chloride, and anhydrous zinc chloride into a uniform mixed powder at a mass ratio of 6 - 8:1 - 2:0.5 - 1 at room temperature; Then, place the mixed powder in a saturated N₂ atmosphere and heat - treat it in a tubular furnace at 600 - 1000 °C for 3 - 4 h. After removal, ultrasonically treat it in hydrochloric acid with a concentration of 1 - 3 mol / L for 0.5 - 2 h. Wash the white precipitate thoroughly with deionized water and dry it in a vacuum drying oven at 60 - 80 °C to obtain the modified degradation agent; The modified degradation agent removes the organic pollutants in the organic - polluted water body through adsorption coprecipitation, surface complexation, reduction, and oxidation mechanisms. In addition, the hydrogen - bond organic framework has a hierarchical pore structure and a high specific surface area, and has a high adsorption capacity for the organic pollutants in the organic - polluted water body.

2. The method for purifying organic polluted water body by the constructed wetland of plants according to claim 1, characterized in that, The wetland fillers (112) are selected from at least one of calcined clay, biochar, vermiculite, zeolite, volcanic rock, perlite, and aerated concrete blocks.

3. The method for purifying organic polluted water body by the constructed wetland according to claim 1, characterized in that The coarse aggregate is selected from at least one of natural crushed stones with a particle size range of 5 - 16.5 mm, 10 - 20 mm, and 16.5 - 31.5 mm; the fine aggregate is selected from at least one of manufactured sand, natural sand, and tailings sand with a particle size range of 50 - 200 μm; the cement is selected from P·O 42.5 grade cement; the hydrotalcite is selected from carbonate-type magnesium-aluminum hydrotalcite with a particle size range of 0.5 - 2 μm; the admixture is selected from ZS-2 type vegetation-growing admixture.

4. The method for purifying organic polluted water body by the constructed wetland according to claim 1, characterized in that The preparation of the modified water purification filler includes the following steps: After uniformly stirring and mixing the coarse aggregate, fine aggregate, cement, water, hydrotalcite, modified degradation agent, and ZS-2 type vegetation-growing admixture, a cube is made according to the manufacturing process of mold filling, manual vibration, compaction, and demolding after standing for 24 h, and the cube is stacked at the lower part in the treatment tank (111) to obtain the modified water purification filler.

5. The method for purifying organic-polluted water body by using a constructed wetland for plants according to claim 1, characterized in that, The summer plants are selected from at least one of canna, reed, cyperus alternifolius, and alligator weed.

6. The method for purifying organic-polluted water body by using a plant constructed wetland according to claim 1, wherein, The winter plants are selected from at least one of rumex acetosa, cardamine lyrata, iris germanica, and juncus effusus.

7. The method for purifying organic polluted water body by using a constructed wetland for plants according to claim 1, wherein, The influent water distribution pipeline system (114) is composed of several water distribution branch pipes, and each water distribution branch pipe is evenly staggered and laid flat on the cross-section of the wetland filler (112) in the area near the top of the treatment tank (111).

8. The method for purifying organic-polluted water body by a plant constructed wetland according to claim 1, characterized in that The effluent water collection pipeline system (115) is composed of several water collection branch pipes, and each water collection branch pipe is evenly staggered and laid flat on the cross-section of the modified water purification filler (113) in the area near the bottom of the treatment tank (111).

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