A method for repairing and treating rural black and odorous water body

Abstract

The present application belongs to the technical field of black and odorous water treatment, and particularly relates to a method for repairing and treating black and odorous water in rural areas. The present application configures aquatic plants, aquatic animals and microbial communities through a system, combines with water power optimization, and constructs an underwater forest ecological system with self-maintenance capability, so as to realize biological self-purification and long-term stability of the ecological system of the black and odorous water, and is suitable for the treatment of black and odorous water in rural rivers and ponds. Through the closed-loop feedback of excess plankton -> enhanced fish feeding -> excrement promoting plant growth -> absorbing excess nutrients, the ecological balance of the water body is maintained, and the oxygen supply of the photosynthesis of submerged plants is combined with the step-by-step oxygen transfer, so that external aeration is not needed, and zero external energy consumption is realized. In addition, the carrier raw material of the present application is derived from agricultural waste, which reduces the treatment cost and effectively promotes the resource utilization of rural solid waste.

Description

Technical Field

[0001] This invention belongs to the field of black and odorous water body treatment technology, specifically relating to a method for the remediation and treatment of black and odorous water bodies in rural areas. Background Technology

[0002] Rural black and odorous water bodies refer to water bodies that are black and have a pungent odor after long-term sedimentation and biological decomposition, caused by severely polluted rural domestic sewage, aquaculture and agricultural production wastewater, etc.

[0003] The state has formulated relevant standards for black and odorous water bodies in rural areas, which mainly include the following:

[0004] Water quality indicators: must meet the Class III water standard of the "Surface Water Environmental Quality Standard" (GB3838-2002), with the key black and odorous water bodies requiring treatment required to meet the Class V water standard (GB 3838-2002).

[0005] Odor removal requirements: The odor removal rate of the treated black and odorous water body should reach over 90%.

[0006] COD requirement: The COD of the treated black and odorous water body should not exceed 100 mg / L.

[0007] Currently, the remediation of black and odorous water bodies includes physical remediation, chemical remediation, and biological remediation. Physical remediation technologies for black and odorous water bodies mainly include source control and interception of exogenous pollutants; dredging and sediment covering for endogenous pollution control; and aeration and reoxygenation, as well as fresh water supply, to address water hypoxia. Physical remediation, when used alone, only treats the symptoms and not the root cause, and is generally used as a step in other treatment methods in practice. The widely used chemical remediation method both domestically and internationally is flocculation sedimentation, which can purify water bodies in a short time and is characterized by its rapid and effective results. This method involves adding iron-aluminum-containing chemical flocculants to the polluted water to enhance the formation of flocculent sediments, thereby removing suspended particulate matter and dissolved nitrogen and phosphorus nutrients. Since pollutants are only transferred from the water body to the flocculation sedimentation, without fundamentally removing them, this method may trigger endogenous pollution and is mostly used for emergency treatment of black and odorous water bodies. Other methods include chlorination, ozone oxidation, Fenton oxidation, and slow-release oxidation. Chemical methods are simple to operate and fast-acting, but they carry the risk of causing secondary pollution. Bioremediation, as a fundamental means of treating and repairing black and odorous water bodies, is one of the most widely used methods. This method mainly includes phytoremediation and microbial remediation technologies. However, simply planting submerged plants is easily covered by algae when they proliferate, affecting their photosynthesis and growth. Adding microbial agents, due to their poor environmental adaptability, is difficult to stabilize and function stably in complex aquatic environments, lacking systemic synergy, resulting in poor treatment effects. Existing treatment technologies often require high operation and maintenance costs; once the use of chemicals or the operation of equipment is stopped, the water quality is prone to rebound, making it difficult to achieve long-term and stable treatment results.

[0008] Based on this, we propose a method for the remediation and treatment of black and odorous water bodies in rural areas, hoping to address the shortcomings of existing technologies. Summary of the Invention

[0009] The purpose of this invention is to provide a method for the remediation and treatment of black and odorous water bodies in rural areas, addressing existing problems.

[0010] This invention is achieved through the following technical solution:

[0011] A method for remediating and treating polluted water bodies in rural areas includes the following steps:

[0012] S1. Construct submerged plant communities by zone:

[0013] Plant Vallisneria natans in shallow water areas, Hydrilla verticillata in medium water areas, and Myriophyllum spicatum in deep water areas.

[0014] S2, Emergent plant barrier in the water-land transition zone:

[0015] Plant yellow iris and canna lilies within 0-2m of the water's edge;

[0016] S3. Aquatic animal community configuration:

[0017] Release cicadae and river clams into the benthic layer, silver carp and bighead carp into the middle layer, and chironomid larvae and tubifex worms into the decomposition layer.

[0018] S4, Microbial Enhancement:

[0019] Indigenous dominant nitrifying and denitrifying bacteria were screened and isolated from water bodies;

[0020] Add quorum sensing inducers at a concentration of 1-2 mg / L;

[0021] Deploy a sandwich-structured submerged plant biofilm carrier;

[0022] The sandwich-structured submerged plant biofilm carrier includes an upper functional layer, a middle transition layer, and a lower functional layer. The upper functional layer is a graphene-reinforced chitosan composite film; the middle transition layer is a ceramic with a pore gradient structure, in which gel beads are embedded; and the lower functional layer is a slow-release phosphorus adsorption composite material.

[0023] Furthermore, the water depth in the shallow water area mentioned in step S1 is 0.5~1m, and the planting density of Vallisneria natans is 15~20 plants / m². 2 0.5-1g of arbuscular mycorrhizal fungal spore powder was implanted into the root system of each Vallisneria natans plant;

[0024] The water depth in the middle water area is 1-2m, and the planting density of *Hydrilla verticillata* is 20-30 plants / m². 2 ;

[0025] In the deep water area, the water depth is 2-3m, and the planting density of *Myriophyllum spicatum* is 10-15 plants / m². 2 .

[0026] Furthermore, the planting ratio of yellow iris and canna lily mentioned in step S2 is 1:1, and the planting density is 5-8 plants / m². 2 .

[0027] Furthermore, the stocking density of the ring-shaped snails in step S3 is 15-20 snails / m². 2 The stocking density of river clams is 10-15 individuals / m². 2 ;

[0028] The stocking density for silver carp is 80-90 fish / acre, and the stocking density for bighead carp is 40-50 fish / acre.

[0029] The release density of midge larvae is 100-150 larvae / m². 2 The stocking density of tubifex worms is 50-80 worms / m². 2 .

[0030] Furthermore, the process of screening and separating indigenous dominant nitrifying and denitrifying bacteria from the water body in step S4 specifically involves taking samples from the bottom sediment of the water body to be treated and separating indigenous nitrifying and denitrifying bacteria through selective culture.

[0031] Furthermore, the culture media used for the selective culture are as follows:

[0032] Nitrifying bacteria selective culture medium: (NH4)2SO4 0.5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + CaCl2·2H2O 0.1g / L + trace element solution 1mL / L + agar 15g / L;

[0033] Selective culture medium for denitrifying bacteria: KNO3 2g / L + (Na3C6H5O7·2H2O) 5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + NaCl 0.5g / L + trace element solution 1mL / L + agar 15g / L;

[0034] The trace element solution is: FeSO4·7H2O 0.5g / L + MnSO4·4H2O 0.15g / L + CuSO4·5H2O 0.03g / L + ZnSO4·7H2O 0.1g / L + Na2MoO4·2H2O 0.02g / L.

[0035] Furthermore, the quorum sensing inducer mentioned in step S4 is an acyl homoserine lactone (AHL) inducer.

[0036] Furthermore, the sandwich structure submerged plant biofilm carrier described in step S4 is deployed at a density of one carrier per 10 square meters.

[0037] The preparation of the sandwich-structured submerged plant biofilm carrier includes the following steps:

[0038] (1) Preparation of the upper functional layer:

[0039] Graphene was ultrasonically dispersed in a 1% (w / v) chitosan acetic acid solution at a solid-liquid ratio of 1g:1000mL until uniformly dispersed. Chitosan powder was added to the dispersion at a mass ratio of 1:5~8 (graphene to chitosan). After stirring until dissolved, citric acid and corn starch were added and stirred until uniformly mixed. The mixture was then poured into a horizontal glass plate mold and allowed to flow naturally at room temperature to form a film with a thickness controlled at 0.1~0.2mm. The film was then dried in a vacuum drying oven at 40~50℃ for 4~5h. After drying, the film was soaked in deionized water for 1.5~2.5h and then air-dried to obtain a graphene-reinforced chitosan composite film.

[0040] (2) Preparation of the intermediate transition layer:

[0041] S2-1. Mix biochar, kaolin, and bentonite in a mass ratio of 1:3:1 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form the first layer of plastic mud.

[0042] S2-2. Mix biochar, kaolin, and bentonite in a mass ratio of 7:9:4 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a second layer of plastic mud.

[0043] S2-3. Mix biochar, kaolin, and bentonite in a mass ratio of 5:3:2 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a third layer of plastic mud.

[0044] S2-4. The first layer of plastic clay, the second layer of plastic clay, and the third layer of plastic clay are compacted and supported in layers from top to bottom to support the ceramic body.

[0045] S2-5. Place the above-mentioned ceramic green body in a muffle furnace, heat it to 600℃ at a rate of 5~6℃ / min, hold it at that temperature for 2~3 hours, and after natural cooling, immerse it in a gel bead suspension. Vacuum adsorption causes the gel beads to embed into the ceramic pores, with a loading density of 50~80 beads / cm³. 3 Vacuum drying at 30~32℃ for 5~6 hours is sufficient;

[0046] (3) Preparation of the lower functional layer:

[0047] S3-1. Dissolve ferrous sulfate in deionized water at a solid-liquid ratio of 1g:200mL, then add 0.6~0.8 times the mass of ferrous sulfate in tea polyphenols. Stir at 200~300rpm for 30~40min under N2 protection, centrifuge, and vacuum dry at 50~60℃ to constant weight to obtain nano-zero valent iron.

[0048] S3-2. After modifying rice straw with 10% citric acid, mix it with aminophosphonic acid resin at a mass ratio of 3:7~8. Then add 5~10% of nano zero-valent iron by total mass, stir evenly, and add deionized water at a solid-liquid ratio of 1:0.2~0.3 to make a paste.

[0049] S3-3. Arrange cotton fibers in parallel in a mold at a spacing of 0.5~0.6cm, then pour in a paste with a thickness of 0.3~0.5cm. After drying at 40~50℃, soak in deionized water for 4~5h, and then air dry at 40~50℃ for 6~8h to obtain a slow-release phosphorus adsorption composite material.

[0050] (4) Assembly:

[0051] Food-grade gelatin and deionized water are heated and dissolved in a mass ratio of 1:5 to make a gelatin paste. The gelatin paste is evenly applied to the lower surface of the upper functional layer, and then attached to the upper surface of the middle transition layer. The mixture is then pressed at 0.1 MPa and allowed to stand for 2-3 hours to cure.

[0052] Apply gelatin paste evenly to the lower surface of the intermediate transition layer, attach it to the upper surface of the lower functional layer, apply pressure of 0.1 MPa and let it stand to cure for 2-3 hours. Finally, place it in a ventilated place at 30-35℃ to dry for 4-5 hours.

[0053] Furthermore, the concentration of acetic acid in the chitosan acetic acid solution described in step (1) is 1%;

[0054] The mass ratio of graphene, citric acid, and corn starch is 2~2.5:1:2~2.5.

[0055] Furthermore, the biochar mentioned in step (2) is made from rice through high-temperature pyrolysis (500~600℃, particle size 0.1~1mm).

[0056] The preparation method of the gel bead suspension described in step (2) S2-5 is as follows: mix sodium alginate and nitrifying bacteria solution at a mass ratio of 3~4:1 and stir to form a uniform gel solution; use a syringe to drop the gel solution into a 2% (w / v) calcium chloride solution to form gel beads with a diameter of 1~2 mm. After standing for 30 min to solidify, take them out and wash them 2~3 times with deionized water. Then add them to deionized water at a solid-liquid ratio of 1g:(5~10)mL and stir to mix well to obtain the gel bead suspension.

[0057] Further, the rice straw modification treatment with 10% citric acid described in step (3) S3-2 is as follows: after crushing the rice straw through a 20-40 mesh sieve, it is immersed in a 10% citric acid solution at a solid-liquid ratio of 1:10. After stirring and mixing, it is placed in a constant temperature water bath at 60-70℃ and stirred at 200-300 rpm for 3-4 hours. After cooling to room temperature, deionized water is added to make the solid-liquid ratio 1:20. Then, the solid is collected by suction filtration, washed with deionized water until the pH of the filtrate is 5-6, and then dried to constant weight.

[0058] The present invention has the following advantages over the prior art:

[0059] 1. This invention belongs to the field of water environment ecological restoration technology, specifically involving a technology for the reconstruction of ecosystems in rural black and odorous water bodies. By systematically configuring aquatic plants, aquatic animals and microbial communities, and combining hydrodynamic optimization, an underwater forest ecosystem with self-sustaining capabilities is constructed, realizing the biological self-purification of black and odorous water bodies and the long-term stability of the ecosystem. It is applicable to the treatment of black and odorous water bodies in rural rivers and ponds.

[0060] 2. The naturally occurring indigenous nitrifying and denitrifying bacteria in black and odorous water bodies are mostly in a free state, easily washed away by water flow, and struggle to form high-density communities, resulting in low nitrogen removal efficiency. The sandwich-structured submerged plant biofilm carrier of this invention possesses high specific surface area, porosity, and biocompatibility. The upper functional layer is a graphene-reinforced chitosan composite film. The high specific surface area of ​​graphene and the biocompatibility of chitosan can rapidly enrich the indigenous nitrifying bacteria in the water body, forming a dense aerobic biofilm. This biofilm not only resists water flow erosion but also provides a sufficient aerobic environment for nitrifying bacteria metabolism through efficient oxygen transfer within the membrane, enhancing ammonia nitrogen oxidation efficiency. The middle transition layer is a ceramic substrate with a pore gradient structure, embedded with gel beads, enabling gradient distribution and efficient loading of microorganisms. The lower functional layer is a slow-release phosphorus adsorption composite material, composed of tea polyphenol-modified nano-zero-valent iron, citric acid-modified rice straw, and aminophosphonic acid resin. It combines phosphorus adsorption and slow-release functions, adsorbing and colonizing denitrifying bacteria to form an anaerobic biofilm. Through the synergistic effect of this layered structure, the originally dispersed indigenous nitrifying and denitrifying bacteria in the water can rapidly achieve directional enrichment and stable colonization in each functional layer of the carrier, transforming from a easily lost free state into a highly active, high-density biofilm-like functional bacterial community, providing core microbial support for synergistic nitrification-denitrification nitrogen removal.

[0061] 3. This invention constructs a triple purification system that integrates submerged plants, aquatic animals, and microorganisms. Aquatic plants form aerobic microzones by secreting oxygen through their roots, promoting the conversion of ammonia nitrogen by nitrifying bacteria. Shellfish inhibit algal blooms, and fish excrement provides slow-release nutrients for the plants. The quorum sensing inducer increases the formation rate of biofilm, and the sandwich carrier simultaneously achieves denitrification, phosphorus removal, and heavy metal fixation.

[0062] 4. This invention maintains the ecological balance of the water body through a closed-loop feedback loop: excessive plankton → enhanced fish feeding → plant growth promoted by excrement → absorption of excess nutrients. Simultaneously, submerged plants provide oxygen through photosynthesis, combined with a stepped oxygen transfer system, eliminating the need for external aeration and achieving zero external energy consumption. Furthermore, the carrier material of this invention is derived from agricultural waste, reducing treatment costs while effectively promoting the resource utilization of rural solid waste. Detailed Implementation

[0063] To further explain the present invention, the following specific embodiments are described.

[0064] Nitrifying bacteria selective culture medium: (NH4)2SO4 0.5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + CaCl2·2H2O 0.1g / L + trace element solution 1mL / L + agar 15g / L;

[0065] Selective culture medium for denitrifying bacteria: KNO3 2g / L + (Na3C6H5O7·2H2O) 5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + NaCl 0.5g / L + trace element solution 1mL / L + agar 15g / L;

[0066] The trace element solution is: FeSO4·7H2O 0.5g / L + MnSO4·4H2O 0.15g / L + CuSO4·5H2O 0.03g / L + ZnSO4·7H2O 0.1g / L + Na2MoO4·2H2O 0.02g / L.

[0067] Unless otherwise specified, the raw materials used in this invention are all from commercially available conventional products.

[0068] Example 1

[0069] A method for remediating and treating polluted water bodies in rural areas includes the following steps:

[0070] S1. Construct submerged plant communities by zone:

[0071] Shallow water area: Plant Vallisneria natans at a density of 15 plants / m² 2 0.5g of arbuscular mycorrhizal fungal spore powder was implanted into the root system of each *Vallisneria natans* plant;

[0072] In the middle-water area: plant Hydrilla verticillata at a density of 20 plants / m². 2 ;

[0073] Deep water area: Plant *Myriophyllum spicatum* at a density of 10 plants / m². 2 ;

[0074] S2, Emergent plant barrier in the water-land transition zone:

[0075] Plant yellow iris and canna lily within 1 meter of the water's edge, at a ratio of 1:1 and a planting density of 5 plants / m². 2 ;

[0076] S3. Aquatic animal community configuration:

[0077] 15 ringed snails and 10 river clams were released per square meter in the benthic layer, 80 silver carp and 40 bighead carp were released per acre in the middle water layer, and 100 chironomid larvae and 50 tubifex worms were released per square meter in the decomposition layer.

[0078] S4, Microbial Enhancement:

[0079] Samples were taken from the sediment of the water body to be treated, and indigenous nitrifying and denitrifying bacteria were separated by selective culture.

[0080] Add acylhomoserine lactone (AHL) inducers at a concentration of 1 mg / L;

[0081] Deploy a sandwich-structured submerged plant biofilm carrier;

[0082] The sandwich-structured submerged plant biofilm carrier is deployed at a density of one carrier per 10 square meters.

[0083] The preparation of the sandwich-structured submerged plant biofilm carrier includes the following steps:

[0084] (1) Preparation of the upper functional layer:

[0085] Graphene was ultrasonically dispersed in a 1% (w / v) chitosan-acetic acid solution (acetic acid concentration of 1%) at a solid-liquid ratio of 1g:1000mL until uniformly dispersed. Chitosan powder was added to the dispersion at a mass ratio of 1:5 (graphene to chitosan). After stirring until dissolved, citric acid and corn starch were added at a mass ratio of 2:1:2 (graphene:citric acid:corn starch). The mixture was stirred and poured into a horizontal glass mold and allowed to flow naturally at room temperature to form a film with a thickness controlled at 0.1mm. The film was then dried in a vacuum drying oven at 40℃ for 4 hours. After drying, the film was soaked in deionized water for 1.5 hours and then air-dried to obtain the upper functional layer.

[0086] (2) Preparation of the intermediate transition layer:

[0087] S2-1. Mix biochar (made from rice pyrolysis at high temperature), kaolin, and bentonite in a mass ratio of 1:3:1 until uniform, and add starch paste in a ratio of 1:0.3 and stir to form the first layer of plastic mud.

[0088] S2-2. Mix biochar, kaolin, and bentonite in a mass ratio of 7:9:4 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a second layer of plastic mud.

[0089] S2-3. Mix biochar, kaolin, and bentonite in a mass ratio of 5:3:2 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a third layer of plastic mud.

[0090] S2-4. The first layer of plastic clay, the second layer of plastic clay, and the third layer of plastic clay are compacted and supported in layers from top to bottom to support the ceramic body.

[0091] S2-5. Place the above-mentioned ceramic green body in a muffle furnace, heat it to 600℃ at a rate of 5℃ / min, hold it at that temperature for 2 hours, and after natural cooling, immerse it in a gel bead suspension. Vacuum adsorption causes the gel beads to embed into the ceramic pores, achieving a loading density of 50 beads / cm³. 3 Vacuum drying at 30℃ for 5 hours is sufficient;

[0092] The preparation method of the gel bead suspension is as follows: Sodium alginate and nitrifying bacteria solution are mixed at a mass ratio of 3:1 and stirred to form a uniform gel solution; the gel solution is dropped into a 2% (w / v) calcium chloride solution using a syringe to form gel beads with a diameter of 1 mm. After standing for 30 minutes to solidify, the beads are taken out and washed twice with deionized water. Then, the gel beads are added to deionized water at a solid-liquid ratio of 1 g: 5 mL and stirred to mix well.

[0093] (3) Preparation of the lower functional layer:

[0094] S3-1. Dissolve ferrous sulfate in deionized water at a solid-liquid ratio of 1g:200mL, then add 0.6 times the mass of ferrous sulfate and tea polyphenols. Stir at 200rpm for 30min under N2 protection, centrifuge, and vacuum dry at 50℃ to constant weight to obtain nano-zero valent iron.

[0095] S3-2. After crushing rice straw and passing it through a 20-mesh sieve, soak it in a 10% citric acid solution at a solid-liquid ratio of 1:10. After stirring and mixing, place it in a constant temperature water bath at 60℃ and stir at 200rpm for 3 hours. After cooling to room temperature, add deionized water to make the solid-liquid ratio 1:20. Then filter and collect the solid. Wash the solid with deionized water until the pH of the filtrate is 5 and dry it to constant weight to obtain modified rice straw.

[0096] S3-3. After mixing the modified rice straw and aminophosphonic acid resin at a mass ratio of 3:7, add 5% of the total mass of nano zero-valent iron, stir evenly, and add deionized water at a solid-liquid ratio of 1:0.2 to make a paste.

[0097] S3-4. Arrange cotton fibers in parallel in the mold at a spacing of 0.5cm, then pour in the paste, controlling the thickness to 0.3cm. After drying at 40℃, soak in deionized water for 4 hours, and then air dry at 40℃ for 6 hours.

[0098] (4) Assembly:

[0099] Food-grade gelatin and deionized water are heated and dissolved in a mass ratio of 1:5 to make a gelatin paste. The gelatin paste is evenly applied to the lower surface of the upper functional layer, and then attached to the upper surface of the middle transition layer. The mixture is then pressed at 0.1 MPa and allowed to stand for 2 hours to cure.

[0100] Apply gelatin paste evenly to the lower surface of the intermediate transition layer, attach it to the upper surface of the lower functional layer, apply pressure of 0.1 MPa and let it stand to cure for 2 hours. Finally, place it in a ventilated place at 30°C to dry for 4 hours.

[0101] Example 2

[0102] A method for remediating and treating polluted water bodies in rural areas includes the following steps:

[0103] S1. Construct submerged plant communities by zone:

[0104] Shallow water area: Plant Vallisneria natans at a density of 16 plants / m² 2 Each plant of *Vallisneria natans* was inoculated with 0.8g of arbuscular mycorrhizal fungal spore powder.

[0105] In the middle-water area: plant Hydrilla verticillata at a density of 25 plants / m². 2 ;

[0106] Deep water area: Plant *Myriophyllum spicatum* at a density of 12 plants / m². 2 ;

[0107] S2, Emergent plant barrier in the water-land transition zone:

[0108] Plant yellow iris and canna lily within 1 meter of the water's edge, at a ratio of 1:1 and a planting density of 6 plants / m². 2 ;

[0109] S3. Aquatic animal community configuration:

[0110] 17 ringed snails and 12 river clams were released per square meter in the benthic layer, 85 silver carp and 45 bighead carp were released per acre in the middle water layer, and 125 chironomid larvae and 65 tubifex worms were released per square meter in the decomposition layer.

[0111] S4, Microbial Enhancement:

[0112] Samples were taken from the sediment of the water body to be treated, and indigenous nitrifying and denitrifying bacteria were separated by selective culture.

[0113] Add acylhomoserine lactone (AHL) inducers at a concentration of 1.5 mg / L;

[0114] Deploy a sandwich-structured submerged plant biofilm carrier;

[0115] The sandwich-structured submerged plant biofilm carrier is deployed at a density of one carrier per 10 square meters.

[0116] The preparation of the sandwich-structured submerged plant biofilm carrier includes the following steps:

[0117] (1) Preparation of the upper functional layer:

[0118] Graphene was ultrasonically dispersed in a 1% (w / v) chitosan-acetic acid solution (acetic acid concentration of 1%) at a solid-liquid ratio of 1g:1000mL until uniformly dispersed. Chitosan powder was added to the dispersion at a mass ratio of 1:6 (graphene to chitosan). After stirring until dissolved, citric acid and corn starch were added at a mass ratio of 2:1:2 (graphene:citric acid:corn starch). The mixture was stirred and poured into a horizontal glass mold and allowed to flow naturally at room temperature to form a film with a thickness controlled at 0.15mm. The film was then dried in a vacuum drying oven at 45℃ for 4.5h. After drying, the film was soaked in deionized water for 2h and then air-dried to obtain the upper functional layer.

[0119] (2) Preparation of the intermediate transition layer:

[0120] S2-1. Mix biochar (made from rice pyrolysis at high temperature), kaolin, and bentonite in a mass ratio of 1:3:1 until uniform, and add starch paste in a ratio of 1:0.3 and stir to form the first layer of plastic mud.

[0121] S2-2. Mix biochar, kaolin, and bentonite in a mass ratio of 7:9:4 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a second layer of plastic mud.

[0122] S2-3. Mix biochar, kaolin, and bentonite in a mass ratio of 5:3:2 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a third layer of plastic mud.

[0123] S2-4. The first layer of plastic clay, the second layer of plastic clay, and the third layer of plastic clay are compacted and supported in layers from top to bottom to support the ceramic body.

[0124] S2-5. Place the above-mentioned ceramic green body in a muffle furnace, heat it to 600℃ at a rate of 5.5℃ / min, hold it at that temperature for 2.5h, and after natural cooling, immerse it in a gel bead suspension. Vacuum adsorption causes the gel beads to embed into the ceramic pores, achieving a loading density of 60 beads / cm³. 3 It can be dried under vacuum at 31℃ for 5.5 hours;

[0125] The preparation method of the gel bead suspension is as follows: Sodium alginate and nitrifying bacteria solution are mixed at a mass ratio of 3.5:1 and stirred to form a uniform gel solution; the gel solution is dropped into a 2% (w / v) calcium chloride solution using a syringe to form gel beads with a diameter of 1.5 mm. After standing for 30 minutes to solidify, the beads are taken out and washed twice with deionized water. Then, the gel beads are added to deionized water at a solid-liquid ratio of 1 g: 7 mL and stirred to mix well.

[0126] (3) Preparation of the lower functional layer:

[0127] S3-1. Dissolve ferrous sulfate in deionized water at a solid-liquid ratio of 1g:200mL, then add 0.7 times the mass of tea polyphenols to the solution. Stir at 250rpm for 35min under N2 protection, centrifuge, and vacuum dry at 55℃ to constant weight to obtain nano-zero valent iron.

[0128] S3-2. After crushing rice straw and passing it through a 40-mesh sieve, soak it in a 10% citric acid solution at a solid-liquid ratio of 1:10. After stirring and mixing, place it in a constant temperature water bath at 65℃ and stir at 250rpm for 3.5h. After cooling to room temperature, add deionized water to make the solid-liquid ratio 1:20. Then filter, collect the solid, wash it with deionized water until the pH of the filtrate is 5, and dry it to constant weight to obtain modified rice straw.

[0129] S3-3. Mix the modified rice straw and aminophosphonic acid resin at a mass ratio of 3:7.5, add 7% of the total mass of nano zero-valent iron, stir evenly, add deionized water at a solid-liquid ratio of 1:0.25, and adjust into a paste.

[0130] S3-4. Arrange cotton fibers in parallel in the mold at a spacing of 0.55cm, then pour in the paste, controlling the thickness to 0.4cm. After drying at 45℃, soak in deionized water for 4.5h, and then air dry at 45℃ for 7h.

[0131] (4) Assembly:

[0132] Food-grade gelatin and deionized water were heated and dissolved in a mass ratio of 1:5 to make a gelatin paste. The gelatin paste was evenly applied to the lower surface of the upper functional layer, and then attached to the upper surface of the middle transition layer. The mixture was then pressed at 0.1 MPa and allowed to stand for 2.5 hours to cure.

[0133] Apply gelatin paste evenly to the lower surface of the intermediate transition layer, attach it to the upper surface of the lower functional layer, apply pressure of 0.1 MPa and let it stand to cure for 2.5 hours. Finally, place it in a ventilated place at 30°C to dry for 4 hours.

[0134] Example 3

[0135] A method for remediating and treating polluted water bodies in rural areas includes the following steps:

[0136] S1. Construct submerged plant communities by zone:

[0137] Shallow water area: Plant Vallisneria natans at a density of 20 plants / m² 2 1g of arbuscular mycorrhizal fungal spore powder was inoculated into the root system of each *Vallisneria natans* plant;

[0138] In the middle-water area: plant Hydrilla verticillata at a density of 30 plants / m². 2 ;

[0139] Deep water area: Plant *Myriophyllum spicatum* at a density of 15 plants / m². 2 ;

[0140] S2, Emergent plant barrier in the water-land transition zone:

[0141] Plant yellow iris and canna lily within 2 meters of the water's edge at a ratio of 1:1 and a planting density of 8 plants / m². 2 ;

[0142] S3. Aquatic animal community configuration:

[0143] 20 ringed snails and 15 river clams were released per square meter in the benthic layer, 90 silver carp and 50 bighead carp were released per acre in the middle water layer, and 150 chironomid larvae and 80 tubifex worms were released per square meter in the decomposition layer.

[0144] S4, Microbial Enhancement:

[0145] Samples were taken from the sediment of the water body to be treated, and indigenous nitrifying and denitrifying bacteria were separated by selective culture.

[0146] Add acylhomoserine lactone (AHL) inducers at a concentration of 2 mg / L;

[0147] Deploy a sandwich-structured submerged plant biofilm carrier;

[0148] The sandwich-structured submerged plant biofilm carrier is deployed at a density of one carrier per 10 square meters.

[0149] The preparation of the sandwich-structured submerged plant biofilm carrier includes the following steps:

[0150] (1) Preparation of the upper functional layer:

[0151] Graphene was ultrasonically dispersed in a 1% (w / v) chitosan-acetic acid solution (acetic acid concentration of 1%) at a solid-liquid ratio of 1g:1000mL until uniformly dispersed. Chitosan powder was added to the dispersion at a mass ratio of 1:8 (graphene to chitosan). After stirring until dissolved, citric acid and corn starch were added at a mass ratio of 2.5:1:2.5 (graphene:citric acid:corn starch). The mixture was stirred and poured into a horizontal glass mold and allowed to flow naturally at room temperature to form a film with a thickness controlled at 0.2mm. The film was then dried in a vacuum drying oven at 50℃ for 5 hours. After drying, the film was soaked in deionized water for 2.5 hours and then air-dried to obtain the upper functional layer.

[0152] (2) Preparation of the intermediate transition layer:

[0153] S2-1. Mix biochar (made from rice pyrolysis at high temperature), kaolin, and bentonite in a mass ratio of 1:3:1 until uniform, and add starch paste in a ratio of 1:0.3 and stir to form the first layer of plastic mud.

[0154] S2-2. Mix biochar, kaolin, and bentonite in a mass ratio of 7:9:4 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a second layer of plastic mud.

[0155] S2-3. Mix biochar, kaolin, and bentonite in a mass ratio of 5:3:2 until homogeneous, and add starch paste in a ratio of 1:0.3 and stir to form a third layer of plastic mud.

[0156] S2-4. The first layer of plastic clay, the second layer of plastic clay, and the third layer of plastic clay are compacted and supported in layers from top to bottom to support the ceramic body.

[0157] S2-5. Place the above-mentioned ceramic green body in a muffle furnace, heat it to 600℃ at a rate of 6℃ / min, hold it at that temperature for 3 hours, and after natural cooling, immerse it in a gel bead suspension. Vacuum adsorption causes the gel beads to embed into the ceramic pores, achieving a loading density of 80 beads / cm³. 3 Vacuum drying at 32℃ for 6 hours is sufficient;

[0158] The preparation method of the gel bead suspension is as follows: Sodium alginate and nitrifying bacteria solution are mixed at a mass ratio of 4:1 and stirred to form a uniform gel solution; the gel solution is dropped into a 2% (w / v) calcium chloride solution using a syringe to form gel beads with a diameter of 2 mm. After standing for 30 minutes to solidify, the beads are taken out and washed 3 times with deionized water. Then, the gel beads are added to deionized water at a solid-liquid ratio of 1 g: 10 mL and stirred to mix well.

[0159] (3) Preparation of the lower functional layer:

[0160] S3-1. Dissolve ferrous sulfate in deionized water at a solid-liquid ratio of 1g:200mL, then add 0.8 times the mass of ferrous sulfate tea polyphenols. Under N2 protection, stir at 300rpm for 40min, centrifuge, and vacuum dry at 60℃ to constant weight to obtain nano-zero valent iron.

[0161] S3-2. After crushing rice straw and passing it through a 40-mesh sieve, soak it in a 10% citric acid solution at a solid-liquid ratio of 1:10. After stirring and mixing, place it in a constant temperature water bath at 70℃ and stir at 300rpm for 4 hours. After cooling to room temperature, add deionized water to make the solid-liquid ratio 1:20. Then filter and collect the solid. Wash the solid with deionized water until the pH of the filtrate is 6 and dry it to constant weight to obtain modified rice straw.

[0162] S3-3. Mix the modified rice straw and aminophosphonic acid resin at a mass ratio of 3:8, add 10% of the total mass of nano zero-valent iron, stir evenly, add deionized water at a solid-liquid ratio of 1:0.3, and adjust into a paste.

[0163] S3-4. Arrange cotton fibers in parallel in the mold at a spacing of 0.6cm, then pour in the paste, controlling the thickness to 0.5cm. After drying at 50℃, soak in deionized water for 5 hours, and then air dry at 50℃ for 8 hours.

[0164] (4) Assembly:

[0165] Food-grade gelatin and deionized water are heated and dissolved in a mass ratio of 1:5 to make a gelatin paste. The gelatin paste is evenly applied to the lower surface of the upper functional layer, and then attached to the upper surface of the middle transition layer. The mixture is then pressed at 0.1 MPa and allowed to stand for 3 hours to cure.

[0166] Apply gelatin paste evenly to the lower surface of the intermediate transition layer, attach it to the upper surface of the lower functional layer, apply pressure of 0.1 MPa and let it stand to cure for 3 hours, and finally place it in a ventilated place at 35℃ to dry for 5 hours.

[0167] Comparative Example 1

[0168] Compared with Example 2, Comparative Example 1 omits the installation of the sandwich-structured submerged plant biofilm carrier, while the other steps are the same as in Example 2.

[0169] Comparative Example 2

[0170] Compared with Example 2, Comparative Example 2 omits the addition of acyl homoserine lactone (AHL) inducers, while the other steps are the same as in Example 2.

[0171] Comparative Example 3

[0172] Compared with Example 2, Comparative Example 3 omits the implantation of arbuscular mycorrhizal fungal spores in the cultivation of Vallisneria natans, while the other steps are the same as in Example 2.

[0173] Comparative Example 4

[0174] Compared with Example 2, Comparative Example 4 omits the microbial enhancement step, while the other steps are the same as in Example 2.

[0175] The water bodies were treated according to the remediation and treatment methods for black and odorous water bodies in the examples and comparative examples. The treatment period was 180 days. The parameters such as COD, ammonia nitrogen, and total phosphorus of the treated water bodies were measured. The test results are shown in Table 1 below.

[0176] Table 1

[0177] COD (mg / L) Ammonia nitrogen (mg / L) Total phosphorus (mg / L) DO (mg / L) Deodorization rate (%) Example 1 65 1.2 0.23 7.0 96 Example 2 62 1.1 0.22 7.0 97 Example 3 63 1.3 0.21 6.8 97 Comparative Example 1 115 9.2 1.6 3.0 63 Comparative Example 2 85 3.8 0.75 5.3 83 Comparative Example 3 70 1.8 0.45 6.2 92 Comparative Example 4 140 15.5 2.8 1.8 20

[0178] Note: Initial water quality: COD=185mg / L, ammonia nitrogen=25mg / L, total phosphorus=3.8mg / L, dissolved oxygen DO=1.2mg / L, deodorization rate=0%.

[0179] As can be seen from Table 1 above, compared with the comparative example, the rural black and odorous water body remediation and treatment method provided by the present invention can simultaneously achieve denitrification, phosphorus removal, and deodorization, and the effect is significant.

[0180] Compared with Example 2, Comparative Example 1 omitted the sandwich structure of the submerged plant biofilm carrier. The ammonia nitrogen removal rate decreased from 95.6% to 63.2%, the total phosphorus removal rate decreased from 94.2% to 57.9%, the COD removal rate decreased from 66.5% to 37.8%, the DO decreased from 7.0 mg / L to 3.0 mg / L, and the deodorization rate decreased from 97% to 63%. This indicates that the absence of the carrier prevented the indigenous nitrifying / denitrifying bacteria from establishing a stable colony, and also resulted in the loss of the carrier's ability to adsorb phosphorus. The effect was significantly worse than that of Example 2.

[0181] Compared with Example 2, Comparative Example 2 omitted the addition of AHLs inducers, resulting in a decrease in ammonia nitrogen removal rate from 95.6% to 84.8%, total phosphorus removal rate from 94.2% to 80.2%, and DO from 7.0 mg / L to 5.3 mg / L. The absence of these inducers led to a decrease in the microbial metabolic rate, thus the treatment effect was weaker than that of Example 2.

[0182] Comparative Example 3, which omitted the inoculation of arbuscular mycorrhizal fungal spores, reduced the total phosphorus removal rate from 94.2% to 88.2% when planting Vallisneria natans. The differences in ammonia nitrogen, COD, DO, and deodorization rate were small compared to Example 2, indicating that the omission of Vallisneria natans mainly affected the plant's phosphorus absorption efficiency.

[0183] Compared with Example 2, Comparative Example 4, which omitted all microbial enhancement steps, showed the worst remediation effect. The ammonia nitrogen removal rate decreased from 95.6% to 38.0%, the total phosphorus removal rate decreased from 94.2% to 26.3%, the COD removal rate decreased from 66.5% to 24.3%, the DO decreased from 7.0 mg / L to 1.8 mg / L, and the deodorization rate decreased from 97% to 20%. This indicates that relying solely on the self-purification capabilities of plants and animals is insufficient to efficiently degrade the high concentrations of organic matter and nitrogen in black and odorous water bodies, resulting in poor remediation effects.

[0184] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for remediating and treating black and odorous water bodies in rural areas, characterized in that, Includes the following steps: S1. Construct submerged plant communities by zone: Plant Vallisneria natans in shallow water areas, Hydrilla verticillata in medium water areas, and Myriophyllum spicatum in deep water areas. S2, Emergent plant barrier in the water-land transition zone: Plant yellow iris and canna lilies within 0-2m of the water's edge; S3. Aquatic animal community configuration: Release cicadae and river clams into the benthic layer, silver carp and bighead carp into the middle layer, and chironomid larvae and tubifex worms into the decomposition layer. S4, Microbial Enhancement: Indigenous dominant nitrifying and denitrifying bacteria were screened and isolated from water bodies; Add quorum sensing inducers at a concentration of 1-2 mg / L; The quorum sensing inducer is an AHLs inducer; Deploy a sandwich-structured submerged plant biofilm carrier; The sandwich-structured submerged plant biofilm carrier includes an upper functional layer, a middle transition layer, and a lower functional layer. The upper functional layer is a graphene-reinforced chitosan composite film; the middle transition layer is a ceramic with a pore gradient structure, in which gel beads are embedded; and the lower functional layer is a slow-release phosphorus adsorption composite material. The preparation of the sandwich-structured submerged plant biofilm carrier includes the following steps: (1) Preparation of the upper functional layer: Graphene was ultrasonically dispersed in a 1% chitosan acetic acid solution at a solid-liquid ratio of 1g:1000mL until uniformly dispersed. Chitosan powder was added to the dispersion at a mass ratio of graphene to chitosan of 1:5~8. After stirring until dissolved, citric acid and corn starch were added and stirred until uniformly mixed. The mixture was then poured into a horizontal glass plate mold and allowed to flow naturally at room temperature to form a film with a thickness controlled at 0.1~0.2mm. The film was then dried in a vacuum drying oven at 40~50℃ for 4~5h. After drying, the film was soaked in deionized water for 1.5~2.5h and then air-dried to obtain a graphene-reinforced chitosan composite film. (2) Preparation of the intermediate transition layer: S2-1. Mix biochar, kaolin, and bentonite evenly in mass ratios of 1:3:1, 7:9:4, and 5:3:2 respectively. Then add starch paste in a ratio of 1:0.3 and stir to form the first layer of plastic mud, the second layer of plastic mud, and the third layer of plastic mud. S2-2. The first layer of plastic clay, the second layer of plastic clay, and the third layer of plastic clay are compacted and supported in layers from top to bottom to support the ceramic body. S2-3. Place the above-mentioned ceramic green body in a muffle furnace, heat it to 600℃ at a rate of 5~6℃ / min, hold it at that temperature for 2~3 hours, and after natural cooling, immerse it in a gel bead suspension. Vacuum adsorption causes the gel beads to embed into the ceramic pores, with a loading density of 50~80 beads / cm³. 3 Vacuum drying at 30~32℃ for 5~6 hours is sufficient; The preparation method of the gel bead suspension is as follows: Sodium alginate and nitrifying bacteria solution are mixed at a mass ratio of 3~4:1 and stirred to form a uniform gel solution; the gel solution is dropped into a 2% (w / v) calcium chloride solution using a syringe to form gel beads with a diameter of 1~2 mm. After standing for 30 min to solidify, the beads are taken out and washed 2~3 times with deionized water. Then, the gel beads are added to deionized water at a solid-liquid ratio of 1 g:(5~10) mL and stirred to mix well to obtain the gel bead suspension. (3) Preparation of the lower functional layer: S3-1. Dissolve ferrous sulfate in deionized water at a solid-liquid ratio of 1g:200mL, then add 0.6~0.8 times the mass of ferrous sulfate in tea polyphenols. Stir at 200~300rpm for 30~40min under N2 protection, centrifuge, and vacuum dry at 50~60℃ to constant weight to obtain nano-zero valent iron. S3-2. After modifying rice straw with 10% citric acid, mix it with aminophosphonic acid resin at a mass ratio of 3:7~8. Then add 5~10% of nano zero-valent iron by total mass, stir evenly, and add deionized water at a solid-liquid ratio of 1:0.2~0.3 to make a paste. S3-3. Arrange cotton fibers in parallel in a mold at a spacing of 0.5~0.6cm, then pour in a paste with a thickness of 0.3~0.5cm. After drying at 40~50℃, soak in deionized water for 4~5h, and then air dry at 40~50℃ for 6~8h to obtain a slow-release phosphorus adsorption composite material. (4) Assembly: Food-grade gelatin and deionized water are heated and dissolved in a mass ratio of 1:5 to make a gelatin paste. The gelatin paste is evenly applied to the lower surface of the upper functional layer, and then attached to the upper surface of the middle transition layer. The mixture is then pressed at 0.1 MPa and allowed to stand for 2-3 hours to cure. Apply gelatin paste evenly to the lower surface of the intermediate transition layer, attach it to the upper surface of the lower functional layer, apply pressure of 0.1 MPa and let it stand to cure for 2-3 hours. Finally, place it in a ventilated place at 30-35℃ to dry for 4-5 hours.

2. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The shallow water area mentioned in step S1 has a water depth of 0.5~1m, and the planting density of Vallisneria natans is 15~20 plants / m². 2 0.5-1g of arbuscular mycorrhizal fungal spore powder was implanted into the root system of each Vallisneria natans plant; The water depth in the middle water area is 1-2m, and the planting density of *Hydrilla verticillata* is 20-30 plants / m². 2 ; In the deep water area, the water depth is 2-3m, and the planting density of *Myriophyllum spicatum* is 10-15 plants / m². 2 .

3. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The planting ratio of yellow iris and canna lily mentioned in step S2 is 1:1, and the planting density is 5-8 plants / m². 2 .

4. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The stocking density of the ring-shaped snails in step S3 is 15-20 snails / m². 2 The stocking density of river clams is 10-15 individuals / m². 2 ; The stocking density for silver carp is 80-90 fish / acre, and the stocking density for bighead carp is 40-50 fish / acre. The release density of midge larvae is 100-150 larvae / m². 2 The stocking density of tubifex worms is 50-80 worms / m². 2 .

5. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The process of screening and separating indigenous dominant nitrifying and denitrifying bacteria from the water body in step S4 specifically involves taking samples from the bottom sediment of the water body to be treated and separating indigenous nitrifying and denitrifying bacteria through selective culture.

6. The method for remediating and treating black and odorous water bodies in rural areas according to claim 5, characterized in that, The culture media used for the selective culture are as follows: Nitrifying bacteria selective culture medium: (NH4)2SO4 0.5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + CaCl2·2H2O 0.1g / L + trace element solution 1mL / L + agar 15g / L; Selective culture medium for denitrifying bacteria: KNO3 2g / L + (Na3C6H5O7·2H2O) 5g / L + KH2PO4 1g / L + K2HPO4 1g / L + MgSO4·H2O 0.2g / L + NaCl 0.5g / L + trace element solution 1mL / L + agar 15g / L; The trace element solution is: FeSO4·7H2O 0.5g / L + MnSO4·4H2O 0.15g / L + CuSO4·5H2O 0.03g / L + ZnSO4·7H2O 0.1g / L + Na2MoO4·2H2O 0.02g / L; Nitrifying bacteria culture conditions: 28~30℃, aerobic culture for 5~7 days, then pick single colonies for purification; Denitrifying bacteria culture conditions: 30℃, anaerobic environment culture for 3-5 days, then pick single colonies for purification.

7. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The sandwich structure submerged plant biofilm carrier described in step S4 is deployed at a density of one carrier per 10 square meters.

8. The method for remediating and treating black and odorous water bodies in rural areas according to claim 1, characterized in that, The concentration of acetic acid in the chitosan acetic acid solution mentioned in step (1) is 1%; The mass ratio of graphene, citric acid, and corn starch is 2~2.5:1:2~2.5.