An ecological restoration method for improving river water quality

Abstract

This invention discloses an ecological restoration method for improving river water quality, comprising the following steps: S1, cleaning up floating debris on the river surface and solid waste along the banks; S2, deploying ecological floating islands on the river surface; S3, regularly monitoring the main pollutant indicators, water transparency, and dissolved oxygen content in the water. This ecological restoration method scientifically configures submerged plant areas and microbial attachment substrate areas in the vertical space of the ecological floating islands. It utilizes the photosynthetic and nutrient absorption capabilities of submerged plants to reduce nitrogen and phosphorus loads in the water and increase dissolved oxygen. Simultaneously, it incorporates specially modified polymer fibers as biomimetic aquatic plants, utilizing their high specific surface area and specific functional groups to adsorb heavy metals and recalcitrant organic matter in the water, significantly improving the transparency of the river water and the self-purification capacity of the ecosystem.

Description

Technical Field

[0001] This invention belongs to the field of river water purification technology, specifically relating to an ecological restoration method for improving river water quality. Background Technology

[0002] With the acceleration of urbanization and the rapid development of industry and agriculture, river water pollution has become an increasingly prominent problem. Large amounts of industrial wastewater, domestic sewage, and agricultural non-point source pollution are discharged into rivers, leading to excessive levels of nitrogen and phosphorus nutrients, accumulation of heavy metal ions, and increased concentrations of persistent organic pollutants. These pollutants not only cause eutrophication, resulting in algal blooms, black and smelly water, and decreased dissolved oxygen, severely disrupting the balance of aquatic ecosystems, but also threaten human health through the food chain. Therefore, how to efficiently and sustainably improve river water quality and rebuild healthy aquatic ecosystems has become an urgent need in the field of environmental governance.

[0003] Current methods for improving river water quality mainly include physical methods, chemical methods, and biological ecological restoration methods. Physical methods primarily include sediment dredging, artificial aeration, and flushing with water. While physical methods are quick to take effect, they involve large-scale engineering projects, high energy consumption, and often only address the symptoms, not the root cause. Sediment dredging can also cause secondary re-release of pollutants. Chemical methods mainly involve adding flocculants, algaecides, or heavy metal precipitants to the water body. This method is highly effective in removing specific pollutants, but the cost of the chemicals is high, and residual chemical reagents can easily cause secondary pollution and damage the original biological community of the water body.

[0004] In contrast, bioremediation methods have gradually become the mainstream technology due to their advantages such as environmental friendliness, high sustainability, and no secondary pollution. Among them, ecological floating island technology and submerged plant remediation technology are the most widely used. Ecological floating islands utilize the absorption and adsorption of plant roots and the degradation of pollutants by rhizosphere microorganisms; submerged plants increase dissolved oxygen through photosynthesis and inhibit algae growth. In addition, to enhance the purification effect, artificial media (such as biomimetic aquatic plants, elastic fillers, etc.) are often placed in the water as a substrate for microbial attachment to increase biomass.

[0005] However, existing ecological restoration technologies still suffer from the following significant technical shortcomings in practical applications: First, their purification capacity for water bodies with complex pollution is limited and lacks specificity. Traditional floating islands and submerged plants primarily target the removal of nitrogen, phosphorus, and organic matter, but lack effective means to remove increasingly serious heavy metal pollution (such as copper, lead, and zinc). High concentrations of heavy metals are not only difficult for plants to degrade, but also poison plant roots and microorganisms, leading to the collapse of the ecological restoration system. Current single-remediation technologies cannot achieve simultaneous treatment of both eutrophication and heavy metal pollution. Second, artificial biofilm substrates have poor biocompatibility and low biofilm formation efficiency. Existing microbial attachment substrates (bionic aquatic plants) are mostly made by directly drawing ordinary polypropylene, polyethylene, and other polymer materials. These polymer materials are typically highly hydrophobic, with smooth surfaces and chemical inert properties. This makes it difficult for microorganisms to quickly attach and reproduce on their surfaces, resulting in a long biofilm formation initiation period and easy detachment under water flow, leading to unstable treatment efficiency. Third, there is a lack of long-term mechanisms for phosphate removal. Although plants can absorb some phosphorus during growth, the phosphorus is released back into the water after the plants die and decompose. Ordinary polymeric carriers have almost no adsorption capacity for anionic phosphates, which means that ecological restoration systems often lack the effectiveness in addressing excessive total phosphorus levels.

[0006] Therefore, developing a modified polymer matrix material that combines multiple functions such as phosphorus removal, nitrogen removal, and heavy metal removal, with fast biofilm formation and high bioactivity, and scientifically integrating it with phytoremediation technology, is key to solving the current complex river water quality problems. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide an ecological restoration method for improving river water quality.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] An ecological restoration method for improving river water quality includes the following steps:

[0010] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0011] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0012] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0013] Preferably, the boundary between the upper plant area and the lower substrate area described in step S2 is located at 1 / 3 to 2 / 3 of the vertical height of the suspension net.

[0014] Preferably, the submerged plant in step S2 is one or more of the following: Elodea nuttallii, Vallisneria natans, Myriophyllum spicatum, Potamogeton crispus, Ceratophyllum demersum, and Potamogeton crispus; the planting density of the submerged plant is 20-40 plants / m². 2 .

[0015] In this invention, submerged plants are the foundation for maintaining aquatic biodiversity. When submerged plants are dominant, the water quality is clear and biodiversity is high. Submerged plants have the characteristic of absorbing excess nutrients, which can reduce the nutrient level of the water and reduce sediment resuspension caused by wind and fish feeding on benthic organisms, thereby reducing turbidity. The leaves, stems and roots of submerged plants have well-developed aerenchyma tissues, and their intercellular spaces form an aerenchyma network. Oxygen produced by photosynthesis in the leaves can be transported to the stems and roots. While meeting the needs of respiration and metabolism, excess oxygen can also diffuse into the water or around the roots, forming a local aerobic zone and improving water quality.

[0016] Preferably, the microbial attachment substrate in step S2 is a modified polymer fiber filament; the modified polymer fiber filament is bundled to form a biomimetic aquatic plant bundle with a diameter of 3-8 cm, and the biomimetic aquatic plant bundle is evenly suspended on the suspension net at a density of 9-16 bundles per square meter.

[0017] Preferably, the method for preparing the modified polymer fiber includes the following steps:

[0018] (a) Add zeolite powder to a mixed metal salt solution, then add ammonia dropwise to adjust the pH, heat and stir, filter, wash, dry and calcine after stirring to obtain composite zeolite powder; then add composite zeolite powder to an ethanol aqueous solution, add vinyltriethoxysilane, stir and react, filter, wash and dry after reaction to obtain ethylene-modified composite zeolite powder.

[0019] (b) Ethylene-modified composite zeolite powder was added to DMF, followed by the addition of 3-mercaptopropionic acid and azobisisobutyronitrile. The reaction was carried out under nitrogen protection at a constant temperature. After the reaction was completed, the mixture was filtered, washed, and dried to obtain organic composite zeolite powder.

[0020] (c) Add organic composite zeolite powder to DMF, then add EDC and NHS, stir and activate, then add 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 7.0-8.0, stir and react, filter, wash and dry after the reaction is completed to obtain modified zeolite filler;

[0021] (d) Polypropylene, modified zeolite filler, polyethylene glycol, antioxidant and zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fiber. After cooling and stretching, the nascent fiber is immersed in a hot water bath, dried and wound to obtain modified polymer fiber filament.

[0022] Preferably, in step (a), the mixed metal salt solution is composed of lanthanum salt and zirconium salt, with the concentration of lanthanum salt being 0.1-0.3 mol / L and the concentration of zirconium salt being 0.1-0.3 mol / L; the mass concentration of the ammonia water is 20-25%; and the pH is 10-11. The mass ratio of the zeolite powder to the mixed metal salt solution is 100:1000-1500. The heating and stirring temperature is 60-80℃, the stirring speed is 300-500 r / min, and the time is 4-6 h. The calcination temperature is 450-550℃, and the time is 1-2 h. The mass concentration of ethanol in the ethanol-water solution is 90-95%, and the mass ratio of the composite zeolite powder to vinyltriethoxysilane is 100:5-8. The heating reaction temperature is 50-60℃, and the time is 6-8 h.

[0023] In this invention, zeolite powder is used as the raw material. Zeolite itself has a regular pore structure and a large number of exchangeable cations. Through ion exchange, ammonia nitrogen ions in water are captured. Lanthanum zirconium metal oxide is generated in situ on the zeolite using an in-situ co-precipitation method. Lanthanum and zirconium metal ions are strong Lewis acids and have a very high natural affinity for phosphate, which is a Lewis base. Compared with simply physically mixing two powders (such as zeolite powder and lanthanum oxide powder), the in-situ generation method can make the metal oxide firmly loaded on the inner and outer surfaces of the zeolite in the form of highly dispersed nanoparticles, which greatly increases the effective contact area and bonding stability. Subsequently, the composite zeolite powder is reacted with vinyltriethoxysilane to introduce active carbon-carbon double bond groups on the zeolite powder, which is beneficial to the subsequent reaction.

[0024] Preferably, in step (b), the mass ratio of ethylene-modified composite zeolite powder, 3-mercaptopropionic acid, and azobisisobutyronitrile is 100:8-12:0.1-0.2, and the isothermal reaction is carried out at a temperature of 65-75°C for 7-10 hours.

[0025] In this invention, 3-mercaptopropionic acid is selected as the key bridging molecule. The efficient click reaction between its thiol group and the vinyl groups on the zeolite surface enables the stable introduction of carboxyl functional groups. Compared to long-chain molecules, the shorter carbon chain structure (C3) of 3-mercaptopropionic acid effectively avoids the coiling, entanglement, and hydrophobic collapse effects of long-chain molecules within the pores, preventing physical blockage of the zeolite microporous channels. Simultaneously, this short-chain flexible spacer arm is sufficient to push the subsequently grafted 5-amino-2-mercaptobenzimidazole macromolecule away from the substrate surface, effectively eliminating steric hindrance. This allows the active nitrogen and sulfur atoms on the benzimidazole ring to fully extend and expose to the aqueous interface, ensuring sufficient contact between wastewater and the functional groups while significantly improving the capture rate and saturated adsorption capacity of the chelating groups for heavy metal ions such as copper, lead, and cadmium in the water.

[0026] Preferably, in step (c), the mass ratio of the organic composite zeolite powder, EDC, NHS, and 5-amino-2-mercaptobenzimidazole is 100:7-10:4-6:5-8; the stirring activation temperature is 20-30℃, the time is 1-2h, and the rotation speed is 150-300r / min; the stirring reaction temperature is 50-60℃, and the time is 8-10h.

[0027] In this invention, 5-amino-2-mercaptobenzimidazole is introduced into the composite boiling powder through an amidation reaction. The powder contains a benzimidazole ring, a thiol group, and an amino group. The amino group participates in the grafting reaction, exposing most of the remaining structure (containing nitrogen heterocycles and thiol groups) to the outside. This allows it to form very stable chelates with heavy metal ions in water, thereby significantly reducing the toxicity of the water.

[0028] Preferably, the mass ratio of each component in step (d) is as follows: 80-90 parts polypropylene, 13-17 parts modified zeolite filler, 5-8 parts polyethylene glycol, 0.2-0.5 parts antioxidant, and 0.5-1 parts zinc stearate; the melting and plasticizing temperature is 200-230℃, the stretching ratio for stretching and shaping is 2-4 times; the temperature of the hot water bath is 80-95℃, and the soaking time is 20-30 minutes.

[0029] In this invention, polypropylene fiber serves as the basic framework, providing mechanical strength and corrosion resistance. A polyethylene glycol pore-forming agent, dispersed in the molten PP to form micro-regions, is dissolved and washed away during subsequent hot water bath treatment, leaving pores. Zinc stearate and antioxidants act as processing aids, ensuring smooth spinning and preventing polymer degradation at high temperatures. The microporous channels created by hot water bath immersion allow water to penetrate into the fiber, directly contacting the modified zeolite filler originally encapsulated by polypropylene. This activates the phosphorus and heavy metal removal functions of the internal filler, significantly improving the utilization rate of the modified polymer fiber ratio. Simultaneously, the micropores provide excellent attachment points for microorganisms, enabling rapid biofilm formation after the fiber enters the water, allowing the attached microbial community to efficiently degrade organic pollutants in the water.

[0030] Preferably, the water surface coverage of the ecological floating island in step S2 is 25-35%.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The ecological restoration method for improving river water quality provided by the present invention scientifically configures the submerged plant area and the microbial attachment substrate area in the vertical space of the ecological floating island. It utilizes the photosynthesis and nutrient absorption capacity of the submerged plants to reduce the nitrogen and phosphorus load of the water body and increase dissolved oxygen. At the same time, it is combined with specially made modified polymer fiber filaments as biomimetic aquatic plants. It utilizes its high specific surface area and specific functional groups to adsorb heavy metals and recalcitrant organic matter in the water body. This synergistic effect of physical adsorption, chemical chelation and biodegradation overcomes the defects of traditional single biological restoration technology, which is slow to take effect and has poor resistance to shock load. It significantly improves the transparency of river water quality and the self-purification capacity of the ecosystem.

[0033] (2) The ecological restoration method for improving river water quality provided by this invention utilizes the strong affinity of lanthanum (La) and zirconium (Zr) bimetallic hydroxides loaded onto the pores and surface of zeolite to form stable, insoluble phosphate precipitates at the interface. This inorganic modification effectively compensates for the weak adsorption capacity of natural zeolite and polypropylene matrix for anionic pollutants, significantly improving the ability of modified polymer fibers to deeply remove and solidify phosphorus in eutrophic waters. Furthermore, the bimetallic synergistic effect enhances the utilization rate of adsorption sites and the stability of the material. Subsequently, the following methods are employed: 3-Mercaptopropionic acid, acting as a flexible spacer arm, is efficiently and stably introduced onto the zeolite surface via a click reaction. Finally, 5-amino-2-mercaptobenzimidazole is grafted onto it. The introduction of the flexible spacer arm effectively reduces the steric hindrance of subsequent functional molecules, allowing the benzimidazole group to fully extend at the aqueous interface. The abundant nitrogen and sulfur heteroatoms on the benzimidazole ring act as polydentate ligands, forming stable chelates with heavy metal ions such as copper, lead, and cadmium in the water, thereby achieving deep purification of heavy metal pollutants. In addition, the trace carboxyl sites remaining during the reaction can also assist in the adsorption of ammonia nitrogen in the water through ion exchange.

[0034] (3) The ecological restoration method for improving river water quality provided by the present invention introduces water-soluble polyethylene glycol (PEG) into the melt spinning system. Utilizing the phase separation characteristics of PEG with polypropylene and the subsequent hot water bath elution process, a network of interconnected microporous channels is constructed inside and on the surface of the fiber. This porous structure establishes a mass transfer channel between the water and the modified zeolite inside the fiber, allowing the active sites encapsulated by the polymer matrix to be exposed and function. On the other hand, the rough porous surface significantly increases the specific surface area of ​​the fiber, providing ideal attachment sites and shelter for microorganisms, accelerating biofilm formation and biofilm efficiency, and thus enhancing the degradation capacity of chemical oxygen demand (COD) in the water. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of the ecological floating island of the present invention.

[0036] Figure 2 This describes the planar arrangement of the ecological floating islands of this invention. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] Unless otherwise specified, all chemical reagents and materials in this invention are purchased from the market or synthesized from raw materials purchased from the market.

[0039] The polyethylene glycol is PEG-20000.

[0040] Example 1

[0041] An ecological restoration method for improving river water quality includes the following steps:

[0042] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0043] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0044] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0045] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is Elodea nuttallii; and the planting density of the submerged plant is 30 plants / m². 2 The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspension net at a density of 12 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0046] The method for preparing the modified polymer fiber includes the following steps:

[0047] (a) 100g of zeolite powder was added to 1300g of a solution of lanthanum chloride and zirconium chloride (the concentration of lanthanum chloride was 0.2mol / L and the concentration of zirconium chloride was 0.2mol / L). Then, 25% ammonia water was added dropwise to adjust the pH to 10. The mixture was heated and stirred at 70℃ and 400r / min for 5h. After stirring, the mixture was filtered, washed, and dried. The mixture was then calcined at 500℃ for 1.5h to obtain composite zeolite powder. 100g of composite zeolite powder was added to 1L of an ethanol aqueous solution (the mass concentration of ethanol was 95%). Then, 7g of vinyltriethoxysilane was added. The mixture was reacted at 55℃ for 7h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain ethylene-modified composite zeolite powder.

[0048] (b) Add 100g of ethylene-modified composite zeolite powder to 1L of DMF, then add 10g of 3-mercaptopropionic acid and 0.15g of azobisisobutyronitrile. React at 70°C for 9h under nitrogen protection. After the reaction is complete, filter, wash and dry to obtain organic composite zeolite powder.

[0049] (c) Add 100g of organic composite zeolite powder to 1L of DMF, then add 8g of EDC and 5g of NHS, stir and activate at 25℃ and 200r / min for 1.5h, then add 7g of 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 7.5, stir and react at 55℃ for 9h, after the reaction is completed, filter, wash and dry to obtain modified zeolite filler;

[0050] (d) By weight, 85 parts of polypropylene, 15 parts of modified zeolite filler, 7 parts of polyethylene glycol, 0.4 parts of antioxidant, and 0.8 parts of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 90°C for 25 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0051] Example 2

[0052] An ecological restoration method for improving river water quality includes the following steps:

[0053] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0054] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0055] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0056] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is Vallisneria natans; and the planting density of the submerged plant is 30 plants / m². 2The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspended net at a density of 15 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0057] The method for preparing the modified polymer fiber includes the following steps:

[0058] (a) 100g of zeolite powder was added to 1500g of a solution of lanthanum chloride and zirconium chloride (the concentration of lanthanum chloride was 0.3mol / L and the concentration of zirconium chloride was 0.3mol / L). Then, 25% ammonia water was added dropwise to adjust the pH to 11. The mixture was heated and stirred at 80℃ and 500r / min for 4h. After stirring, the mixture was filtered, washed, and dried. The mixture was then calcined at 550℃ for 1h to obtain composite zeolite powder. 100g of composite zeolite powder was added to 1L of an ethanol aqueous solution (the mass concentration of ethanol was 95%). Then, 8g of vinyltriethoxysilane was added. The mixture was reacted at 60℃ for 6h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain ethylene-modified composite zeolite powder.

[0059] (b) Add 100g of ethylene-modified composite zeolite powder to 1L of DMF, then add 12g of 3-mercaptopropionic acid and 0.2g of azobisisobutyronitrile. React at 75°C for 7h under nitrogen protection. After the reaction is complete, filter, wash and dry to obtain organic composite zeolite powder.

[0060] (c) Add 100g of organic composite zeolite powder to 1L of DMF, then add 10g of EDC and 6g of NHS, stir and activate at 30℃ and 300r / min for 1h, then add 8g of 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 8.0, stir and react at 60℃ for 8h, after the reaction is completed, filter, wash and dry to obtain modified zeolite filler;

[0061] (d) By weight, 80 parts of polypropylene, 13 parts of modified zeolite filler, 5 parts of polyethylene glycol, 0.2 parts of antioxidant, and 0.5 parts of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 80°C for 30 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0062] Example 3

[0063] An ecological restoration method for improving river water quality includes the following steps:

[0064] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0065] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0066] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0067] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is *Myriophyllum spicatum*; and the planting density of the submerged plant is 30 plants / m². 2 The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspension net at a density of 12 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0068] The method for preparing the modified polymer fiber includes the following steps:

[0069] (a) 100g of zeolite powder was added to 1000g of lanthanum chloride and zirconium chloride solution (the concentration of lanthanum chloride was 0.1mol / L and the concentration of zirconium chloride was 0.1mol / L), and then 20% ammonia water was added dropwise to adjust the pH to 10. The mixture was heated and stirred at 60℃ and 300r / min for 6h. After stirring, the mixture was filtered, washed, and dried, and then calcined at 450℃ for 2h to obtain composite zeolite powder. 100g of composite zeolite powder was added to 1L of ethanol aqueous solution (the mass concentration of ethanol was 95%), and then 5g of vinyltriethoxysilane was added. The mixture was reacted at 50℃ for 8h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain ethylene-modified composite zeolite powder.

[0070] (b) Add 100g of ethylene-modified composite zeolite powder to 1L of DMF, then add 8g of 3-mercaptopropionic acid and 0.1g of azobisisobutyronitrile. React at 65°C for 10h under nitrogen protection. After the reaction is complete, filter, wash and dry to obtain organic composite zeolite powder.

[0071] (c) Add 100g of organic composite zeolite powder to 1L of DMF, then add 7g of EDC and 4g of NHS, stir and activate at 20℃ and 150r / min for 2h, then add 5g of 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 7.0, stir and react at 50℃ for 10h, filter, wash and dry after the reaction is completed to obtain modified zeolite filler;

[0072] (d) By weight, 90 parts of polypropylene, 17 parts of modified zeolite filler, 8 parts of polyethylene glycol, 0.5 parts of antioxidant, and 1 part of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 95°C for 20 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0073] Comparative Example 1

[0074] An ecological restoration method for improving river water quality includes the following steps:

[0075] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0076] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0077] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0078] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is Elodea nuttallii; and the planting density of the submerged plant is 30 plants / m². 2 The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspension net at a density of 12 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0079] The method for preparing the modified polymer fiber includes the following steps:

[0080] (a) 100g of zeolite powder was added to 1L of ethanol aqueous solution (ethanol mass concentration was 95%), followed by 7g of vinyltriethoxysilane. The mixture was reacted at 55℃ for 7h. After the reaction was completed, the mixture was filtered, washed and dried to obtain ethylene-modified composite zeolite powder.

[0081] (b) Add 100g of ethylene-modified composite zeolite powder to 1L of DMF, then add 10g of 3-mercaptopropionic acid and 0.15g of azobisisobutyronitrile. React at 70°C for 9h under nitrogen protection. After the reaction is complete, filter, wash and dry to obtain organic composite zeolite powder.

[0082] (c) Add 100g of organic composite zeolite powder to 1L of DMF, then add 8g of EDC and 5g of NHS, stir and activate at 25℃ and 200r / min for 1.5h, then add 7g of 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 7.5, stir and react at 55℃ for 9h, after the reaction is completed, filter, wash and dry to obtain modified zeolite filler;

[0083] (d) By weight, 85 parts of polypropylene, 15 parts of modified zeolite filler, 7 parts of polyethylene glycol, 0.4 parts of antioxidant, and 0.8 parts of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 90°C for 25 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0084] Compared to Example 1, no lanthanum zirconium metal oxide was introduced into the modified zeolite filler in this comparative example.

[0085] Comparative Example 2

[0086] An ecological restoration method for improving river water quality includes the following steps:

[0087] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0088] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0089] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0090] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is Elodea nuttallii; and the planting density of the submerged plant is 30 plants / m². 2 The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspension net at a density of 12 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0091] The method for preparing the modified polymer fiber includes the following steps:

[0092] (a) 100g of zeolite powder was added to 1300g of a solution of lanthanum chloride and zirconium chloride (the concentration of lanthanum chloride was 0.2mol / L and the concentration of zirconium chloride was 0.2mol / L). Then, 25% ammonia water was added dropwise to adjust the pH to 10. The mixture was heated and stirred at 70℃ and 400r / min for 5h. After stirring, the mixture was filtered, washed, and dried. The mixture was then calcined at 500℃ for 1.5h to obtain composite zeolite powder. 100g of composite zeolite powder was added to 1L of an ethanol aqueous solution (the mass concentration of ethanol was 95%). Then, 7g of vinyltriethoxysilane was added. The mixture was reacted at 55℃ for 7h. After the reaction was completed, the mixture was filtered, washed, and dried to obtain ethylene-modified composite zeolite powder.

[0093] (b) 100g of ethylene-modified composite zeolite powder was added to 1L of DMF, followed by 10g of 3-mercaptopropionic acid and 0.15g of azobisisobutyronitrile. The mixture was reacted at 70°C for 9 hours under nitrogen protection. After the reaction was completed, the mixture was filtered, washed, and dried to obtain the modified zeolite filler.

[0094] (c) By weight, 85 parts of polypropylene, 15 parts of modified zeolite filler, 7 parts of polyethylene glycol, 0.4 parts of antioxidant and 0.8 parts of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 90°C for 25 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0095] Compared with Example 1, the modified zeolite filler in this comparative example did not introduce 5-amino-2-mercaptobenzimidazole, i.e., step (c) was omitted.

[0096] Comparative Example 3

[0097] An ecological restoration method for improving river water quality includes the following steps:

[0098] S1. Clean up floating debris on the river surface and solid waste along the riverbank;

[0099] S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area.

[0100] S3. Regularly monitor the main pollutant indicators, water transparency, and dissolved oxygen content in the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem.

[0101] In step S2, the boundary between the upper plant area and the lower substrate area is located at half the vertical height of the suspension net; the submerged plant in step S2 is Elodea nuttallii; and the planting density of the submerged plant is 30 plants / m². 2 The microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled into biomimetic aquatic plant bundles with a diameter of 3-8 cm, and the biomimetic aquatic plant bundles are evenly suspended on the suspension net at a density of 12 bundles per square meter. The water surface coverage of the ecological floating island is 30%.

[0102] The method for preparing the modified polymer fiber includes the following steps:

[0103] (a) 100g of zeolite powder was added to 1300g of lanthanum chloride and zirconium chloride solution (the concentration of lanthanum chloride was 0.2mol / L and the concentration of zirconium chloride was 0.2mol / L), and then 25% ammonia water was added dropwise to adjust the pH to 10. The mixture was heated and stirred at 70℃ and 400r / min for 5h. After stirring, the mixture was filtered, washed, dried, and calcined at 500℃ for 1.5h to obtain composite zeolite powder.

[0104] (b) Mix 100g of composite zeolite powder with 7g of 5-amino-2-mercaptobenzimidazole to obtain modified zeolite filler;

[0105] (c) By weight, 85 parts of polypropylene, 15 parts of modified zeolite filler, 7 parts of polyethylene glycol, 0.4 parts of antioxidant and 0.8 parts of zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder at a temperature of 220°C to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fibers. After cooling and stretching, the stretching ratio is 3 times. Then, the masterbatch is immersed in a hot water bath at a temperature of 90°C for 25 minutes. After drying, the masterbatch is wound to obtain modified polymer fiber filaments.

[0106] Compared with Example 1, the modified zeolite filler in this comparative example did not introduce 3-mercaptopropionic acid, but was obtained by physical blending of composite zeolite powder and 5-amino-2-mercaptobenzimidazole.

[0107] A polluted and odorous river in Hubei Province was treated. Water quality indicators were tested before treatment. After three months of ecological restoration, COD, ammonia nitrogen, total phosphorus (TP), and Pb were measured in each water group. 2+ Dissolved oxygen (DO) was measured, and water transparency was observed. Specifically: COD was measured according to the method in HJ 828-2017; ammonia nitrogen was measured according to the method in HJ 536-2009; total phosphorus was measured according to the method in GB11893-1989; and Pb... 2+ The determination was carried out according to the method of GB 7475-1987, and the determination of dissolved oxygen was carried out according to the method of HJ 506-2009. The test results are shown in Table 1 below.

[0108] Table 1

[0109] COD (mg / L) Ammonia nitrogen (mg / L) TP (mg / L) <![CDATA[Pb 2+ (μg / L)]]> DO value (mg / L) Transparency (cm) Before processing 75.5 8.35 1.08 129 2.17 31 Example 1 18.6 0.92 0.11 11 6.39 65 Example 2 19.1 0.94 0.12 17 6.45 67 Example 3 19.9 1.01 0.15 15 6.31 61 Comparative Example 1 26.8 1.72 0.46 42 5.63 43 Comparative Example 2 30.6 2.15 0.28 54 5.16 52 Comparative Example 3 24.2 1.48 0.35 46 3.87 39

[0110] As can be seen from Table 1 above, the ecological restoration method for improving river water quality provided by this invention not only eliminates black and odorous water bodies and improves transparency, but also ensures that the COD, TP, and ammonia nitrogen in the water body all meet the surface water III-IV standards, and the dissolved oxygen DO increases by about 200%, resulting in a fundamental improvement in water quality.

[0111] The above description is a further detailed explanation of the present invention in conjunction with specific implementation examples. It should not be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the protection scope of the present invention.

[0112] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An ecological restoration method for improving river water quality, characterized in that, Includes the following steps: S1. Clean up floating debris on the river surface and solid waste along the riverbank; S2. An ecological floating island is set up on the surface of the river. The ecological floating island includes a rod-shaped floating body and a hanging net. The hanging net is divided into an upper plant area and a lower substrate area in the vertical direction. Seedlings of submerged plants are fixed in the upper plant area and microbial attachment substrate is suspended in the lower substrate area. S3. Regularly monitor the main pollutant indicators, water transparency and dissolved oxygen content of the water body, and observe the growth status of submerged plants. Based on the monitoring results, adjust the population density of submerged plants in a timely manner, and replenish or replace the ecological floating islands to maintain the stability and purification efficiency of the ecosystem. In step S2, the microbial attachment substrate is a modified polymer fiber filament; the modified polymer fiber filament is bundled to prepare a biomimetic aquatic plant bundle with a diameter of 3-8 cm, and the biomimetic aquatic plant bundle is evenly suspended on the suspension net at a density of 9-16 bundles per square meter. The method for preparing the modified polymer fiber includes the following steps: (a) Add zeolite powder to a mixed metal salt solution, then add ammonia dropwise to adjust the pH, heat and stir, filter, wash, dry and calcine after stirring to obtain composite zeolite powder; then add composite zeolite powder to an ethanol aqueous solution, add vinyltriethoxysilane, stir and react, filter, wash and dry after reaction to obtain ethylene-modified composite zeolite powder. (b) Ethylene-modified composite zeolite powder was added to DMF, followed by the addition of 3-mercaptopropionic acid and azobisisobutyronitrile. The reaction was carried out under nitrogen protection at a constant temperature to obtain organic composite zeolite powder. (c) Add organic composite zeolite powder to DMF, then add EDC and NHS, stir and activate, then add 5-amino-2-mercaptobenzimidazole, adjust the pH of the reaction system to 7.0-8.0, stir and react to obtain modified zeolite filler; (d) Polypropylene, modified zeolite filler, polyethylene glycol, antioxidant and zinc stearate are mixed evenly and melt-plasticized through a twin-screw extruder to obtain masterbatch. Then, the masterbatch is extruded through a spinneret to obtain nascent fiber. After cooling and stretching, the nascent fiber is immersed in a hot water bath, dried and wound to obtain modified polymer fiber filament.

2. The ecological restoration method according to claim 1, characterized in that, The boundary between the upper plant area and the lower substrate area mentioned in step S2 is located at 1 / 3 to 2 / 3 of the vertical height of the suspension net.

3. The ecological restoration method according to claim 1, characterized in that, The submerged plant mentioned in step S2 is one or more of the following: Elodea nuttallii, Vallisneria natans, Myriophyllum spicatum, Potamogeton crispus, Ceratophyllum demersum, and Potamogeton crispus; the planting density of the submerged plant is 20-40 plants / m². 2 .

4. The ecological restoration method according to claim 1, characterized in that, The mixed metal salt solution in step (a) is composed of lanthanum salt and zirconium salt, with the concentration of lanthanum salt being 0.1-0.3 mol / L and the concentration of zirconium salt being 0.1-0.3 mol / L. The mass concentration of the ammonia water is 20-25%, and the pH is 10-11. The mass ratio of the zeolite powder to the mixed metal salt solution is 100:1000-1500. The heating and stirring temperature is 60-80℃, the stirring speed is 300-500 r / min, and the time is 4-6 h. The calcination temperature is 450-550℃, and the time is 1-2 h. The mass concentration of ethanol in the ethanol-water solution is 90-95%, and the mass ratio of the composite zeolite powder to vinyltriethoxysilane is 100:5-8. The stirring reaction temperature is 50-60℃, and the time is 6-8 h.

5. The ecological restoration method according to claim 1, characterized in that, In step (b), the mass ratio of ethylene-modified composite zeolite powder, 3-mercaptopropionic acid, and azobisisobutyronitrile is 100:8-12:0.1-0.2, and the isothermal reaction is carried out at a temperature of 65-75°C for 7-10 hours.

6. The ecological restoration method according to claim 1, characterized in that, In step (c), the mass ratio of the organic composite zeolite powder, EDC, NHS, and 5-amino-2-mercaptobenzimidazole is 100:7-10:4-6:5-8; the stirring activation temperature is 20-30℃, the time is 1-2h, and the rotation speed is 150-300r / min; the stirring reaction temperature is 50-60℃, and the time is 8-10h.

7. The ecological restoration method according to claim 1, characterized in that, The mass ratio of each component in step (d) is as follows: 80-90 parts polypropylene, 13-17 parts modified zeolite filler, 5-8 parts polyethylene glycol, 0.2-0.5 parts antioxidant, and 0.5-1 parts zinc stearate; the melting and plasticizing temperature is 200-230℃, the stretching ratio for stretching and shaping is 2-4 times; the temperature of the hot water bath is 80-95℃, and the soaking time is 20-30 minutes.

8. The ecological restoration method according to claim 1, characterized in that, The water surface coverage of the ecological floating islands mentioned in step S2 is 25-35%.

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