An ecological restoration method for heavily polluted water body with bottom mud

Abstract

The present application belongs to the field of environmental remediation technology, and particularly relates to a method for ecological remediation of heavily polluted water body with bottom mud. The method for ecological remediation of heavily polluted water body with bottom mud comprises the following steps: S1: putting heavy metal remediation agent into the water body; S2: putting slow-release type bottom mud remediation agent into the water body; S3: sequentially putting algae-controlling microorganism, photosynthetic bacteria and EM bacteria, and plankton into the water body; S4: planting aquatic plants according to water depth; planting emergent plants in the area with water depth less than 0.5 m, and planting submerged plants in the area with water depth greater than or equal to 1.5 m; and S5: when the coverage rate of aquatic plants in the water body is greater than or equal to 80%, putting aquatic animals into the water body. In the present application, slow-release type bottom mud remediation agent and heavy metal remediation agent are used to reduce the pollution of bottom mud, organic matter, etc., the transparency of the water body is then improved after reduction, aquatic plants are then planted, and finally aquatic animals are put into the water body, so as to construct a water ecological system and achieve the purpose of ecological remediation of the water body.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation technology, and specifically relates to an ecological remediation method for water bodies with severely polluted bottom sediments. Background Technology

[0002] Rivers and lakes polluted by heavy metals and organic pollutants over a long period can negatively impact the quality of the surrounding water environment. Prolonged infiltration of these pollutants can also contaminate groundwater. One of the key challenges in their remediation is the treatment of bottom sediment. Currently, most treatments involve dredging and sanitary landfill. Long-term pollution of bottom sediment leads to the continuous deposition of pollutants such as organic matter, heavy metals, nitrogen, and phosphorus, resulting in severe contamination. In water body ecological restoration projects, the main methods used are dredging, adding quicklime to the sediment, and applying amendments to control sediment pollution before proceeding with the ecological restoration of the water body.

[0003] Aquatic ecological restoration is carried out by planting aquatic plants and constructing aquatic plant ecosystems. However, during the ecological restoration process, there is also the risk of the re-release of pollutants from polluted sediments, which can exacerbate the pollution in the water. Increased pollutants can affect water transparency and the excessive proliferation of algae, reducing water transparency and consequently affecting the photosynthesis and growth of submerged plants, ultimately leading to plant death and the failure of the aquatic ecological restoration project.

[0004] The existing technologies for treating heavily contaminated sediment mainly fall into the following categories: (a) Dredging is commonly used for heavily polluted sediment, but the cost of dredging is relatively high, and it is difficult to transport and dispose of the dredged sediment. Disposal requires sanitary landfilling in landfills. This method is not recommended. In-situ treatment is suggested.

[0005] (b) Treatment with sediment treatment agents is not effective in the sediment for a long time and is prone to causing secondary pollution. There are no treatment agents specifically for heavy metals and organic matter.

[0006] (c) Planting submerged plants in polluted water bodies, but it is necessary to improve the water transparency to promote the growth and stability of submerged plants. This is often achieved by adding microorganisms, zooplankton, and flocculants to improve the water transparency.

[0007] Introducing zooplankton into polluted sediments and water bodies to feed on cyanobacteria and improve water transparency is a common method. However, zooplankton are highly susceptible to environmental degradation and mortality, often used as biomarkers to assess water health. In heavily polluted sediments or water bodies, zooplankton are easily inhibited by pollutants, leading to growth suppression or even death, thus failing to improve water transparency. Furthermore, zooplankton require specialized optimization and domestication to effectively feed on cyanobacteria, presenting professional and patent barriers. Microbial algae control involves two main methods: firstly, competition to reduce phytoplankton populations by squeezing out their space; and secondly, the introduction of microorganisms that specifically destroy phytoplankton. However, microbial algae control requires large quantities, necessitates repeated introductions without achieving the desired transparency improvement, is costly, and lacks synergistic effects with zooplankton. The problem with using flocculants to improve water transparency: While flocculants can remove suspended solids and algae from water, they can easily cause secondary pollution, require multiple applications and large quantities, resulting in high costs and damage to the ecological environment.

[0008] (d) Aquatic plant cultivation: Currently, when cultivating aquatic plants, different species, planting densities, and interspecies of aquatic plants are not planted according to different water depths and air temperatures, which leads to a significant reduction in the treatment effect on heavily polluted bottom sediments. Summary of the Invention

[0009] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide an ecological restoration method for water bodies with heavily polluted bottom sediment.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The first aspect of this invention provides an ecological restoration method for heavily polluted water bodies with sediment, comprising the following steps: S1: Add heavy metal remediation agents to the water body; S2: Add slow-release sediment remediation agent to the water body; S3: First, release algae-controlling microorganisms into the water, then release a mixture of photosynthetic bacteria and EM bacteria, and finally release zooplankton; S4: Plant aquatic plants according to water depth; plant emergent plants in areas with water depth < 0.5m, and plant submerged plants in areas with water depth ≥ 1.5m. S5: When the coverage of aquatic plants in the water body is ≥80%, aquatic animals shall be released into the water body.

[0011] In some embodiments of the present invention, the preparation method further includes a step of sampling and testing the sediment in the water body; the sediment in the water body can be sampled and tested before or after each step of the preparation method. For example, the water body can be sampled and tested before step S1, after step S1 and before step S2, after step S2 and before step S3, after step S3 and before step S4, after step S4 and before step S5, or after step S2, to monitor pH, cadmium, mercury, arsenic, lead, ΣPAHs (total polycyclic aromatic hydrocarbons), total nitrogen, and total phosphorus in the sediment in the water body.

[0012] In some embodiments of the present invention, the algae-controlling microorganisms are Staphylococcus and Flavobacterium tumefaciens in a mass ratio of 1:(0.8~1.2). These algae-controlling microorganisms can secrete extracellular enzymes that have an algicidal effect on cyanobacteria, killing existing cyanobacterial clumps in the water.

[0013] In some embodiments of the present invention, the dosage of the algae-controlling microorganisms is 50-140 g / m³. 3 In some embodiments of the present invention, the dosage of the algae-controlling microorganism is 50 g / m³. 3 60g / m 3 80g / m 3 100g / m 3 110g / m 3 120g / m 3 130g / m 3 140g / m 3 The range of values ​​formed by any one of the values ​​in the range, or any two of them.

[0014] In some embodiments of the present invention, the algae-controlling microorganisms are introduced every 2-4 days. The introduction of algae-controlling microorganisms continues until the water color changes from green to yellowish-green, at which point the introduction is stopped.

[0015] In some embodiments of the present invention, the algae-controlling microorganisms are introduced 2-5 times.

[0016] In some embodiments of the present invention, the volume ratio of photosynthetic bacteria to EM bacteria is 1:(2-4).

[0017] In some embodiments of the present invention, the total amount of photosynthetic bacteria and EM bacteria added is 150-400 mL / m³. 3 In some embodiments of the present invention, the total amount of photosynthetic bacteria and EM bacteria added is 150 mL / m³. 3 180mL / m 3 200mL / m 3 220mL / m 3 250mL / m3 260mL / m 3 280mL / m 3 300mL / m 3 320mL / m 3 350mL / m 3 360mL / m 3 380mL / m 3 400mL / m 3 The range of values ​​formed by any one of the values ​​in the range, or any two of them. After the algae-controlling microorganisms kill the existing blue-green algae, the photosynthetic bacteria and EM bacteria can reduce the nutrients in the water body, while promoting the generation of single-celled algae, which are easy for zooplankton to feed on.

[0018] In some embodiments of the present invention, the zooplankton includes cladocerans; in some embodiments of the present invention, the cladocerans include at least one of water fleas and giant daphnia.

[0019] In some embodiments of the present invention, the amount of zooplankton released is 60-300 g / m³. 3 In some embodiments of the present invention, the amount of zooplankton released is 60 g / m³. 3 80g / m 3 100g / m 3 120g / m 3 150g / m 3 180g / m 3 200g / m 3 220g / m 3 250g / m 3 280g / m 3 300g / m 3 The range of values, or any combination thereof, is defined as follows. The zooplankton are able to feed on the algae that form, thus increasing water transparency.

[0020] In some embodiments of the present invention, step S4 is: planting aquatic plants according to the water depth, and planting emergent plants in areas with a water depth of <0.5m; Submerged plants (A) should be planted in areas with a water depth of 0.5-1.5m. Submerged plants (B) should be planted in areas with a water depth of 1.5-2.5m. Plant submerged plants (C) in areas with a water depth greater than 2.5m; The submerged plant A is selected from at least one of Vallisneria natans and Elaeagnus pungens. The submerged plant B is selected from at least one of the following: Hydrilla verticillata, Elodea nuttallii, Potamogeton crispus, Ceratophyllum demersum, Potamogeton malaianus, Dianthus simonii, and Dianthus macrocarpa. The submerged plant C is selected from at least one of Potamogeton crispus and Myriophyllum spicatum. The emergent plants are selected from at least one of calamus, reed, and lotus.

[0021] In some embodiments of the present invention, the planting density of the submerged plant A is 180-220 plants / m². 2 .

[0022] In some embodiments of the present invention, the planting density of the submerged plant A is 200-250 plants / m². 2 .

[0023] In some embodiments of the present invention, at least one of Elodea nuttallii and Diplophora macrophylla is planted in areas with a water depth of 1.5-2.5m and an annual average temperature of ≤12℃.

[0024] In some embodiments of the present invention, at least one of the following is selected from *Hydrilla verticillata*, *Elodea nuttallii*, *Potamogeton crispus*, *Ceratophyllum demersum*, *Potamogeton malaianus*, *Potamogeton pectinatus*, and *Potamogeton macrocarpa* when the water depth is 1.5-2.5m and the average annual temperature is 12-19℃: *Potamogeton pectinatus*, *Potamogeton pectinatus*, and *Potamogeton macrocarpa*.

[0025] In some embodiments of the present invention, at least one of *Hydrilla verticillata*, *Potamogeton malaianus*, and *Potamogeton pectinatus* is planted in areas where the water depth is 1.5-2.5m and the average annual temperature is greater than 19°C.

[0026] In some embodiments of the present invention, the planting density of the submerged plant C is 220-300 plants / m². 2 .

[0027] In some embodiments of the present invention, the heavy metal remediation agent includes a humic acid-based remediation agent and an encapsulated microbial remediation agent; the raw materials for preparing the humic acid-based remediation agent include humic acid, oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate, and calcium chloride; the encapsulated microbial remediation agent includes a core material and a calcium alginate coating layer; the calcium alginate coating layer coats at least a portion of the surface of the core material; the core material includes a porous carrier and microorganisms; the microorganisms are loaded in the porous carrier; the raw materials for preparing the porous carrier include oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate, and calcium chloride; The oyster shell pretreatment agent includes active calcium and zinc oxide; the active calcium is formed by calcining and hydrating oyster shells sequentially; the chitosan pretreatment agent is formed by activating chitosan with inorganic peroxide.

[0028] The heavy metal remediation agent of this invention utilizes the loose and porous framework structure of oyster shells after high-temperature calcination and modified chitosan (extracts from shrimp shells, crab shells, etc.) to provide a porous material matrix for humic acid and microorganisms, thus preparing a combined physicochemical adsorption and microbial adsorption degradation remediation agent. This not only efficiently solves the problem of heavy metal pollution in water body sediments, but also removes heavy metals from sediments by recovering granular remediation agents, preventing secondary pollution.

[0029] In some embodiments of the invention, the zinc oxide coats at least a portion of the surface of the active calcium.

[0030] In some embodiments of the present invention, the humic acid-based remedial agent is a porous material.

[0031] In some embodiments of the present invention, the humic acid-based repair agent comprises the following raw materials in parts by weight: 8-22 parts humic acid, 23-37 parts oyster shell pretreatment agent, 23-37 parts chitosan pretreatment agent, 8-17 parts sodium alginate, and 8-17 parts calcium chloride. In some specific embodiments of the present invention, the humic acid-based repair agent comprises the following components in parts by weight: 10-20 parts humic acid, 25-35 parts oyster shell pretreatment agent, 25-30 parts chitosan pretreatment agent, 10-15 parts sodium alginate, and 10-15 parts calcium chloride.

[0032] In some embodiments of the present invention, the humic acid-based repair agent is prepared by mixing and granulating the raw materials for preparing the humic acid-based repair agent, and then calcining them at 180-220°C.

[0033] In some embodiments of the present invention, the calcination temperature of the oyster shell is 700~900℃; in some specific embodiments of the present invention, the calcination temperature of the oyster shell is 750~850℃.

[0034] In some embodiments of the present invention, the calcination time of the oyster shell is 0.5 to 2 hours; in some specific embodiments of the present invention, the calcination time of the oyster shell is 0.8 to 1.2 hours.

[0035] In some embodiments of the present invention, the calcination heating rate of the oyster shell is 10~20℃ / min; in some specific embodiments of the present invention, the calcination heating rate of the oyster shell is 13~17℃ / min.

[0036] In some embodiments of the present invention, the hydration is carried out by mixing the calcined product of oyster shells with water and reacting; in some embodiments of the present invention, the mass ratio of the calcined product of oyster shells to water is (2~4):1.

[0037] In some embodiments of the present invention, the porous carrier comprises the following raw materials in parts by weight: 8-22 parts oyster shell pretreatment agent, 48-62 parts chitosan pretreatment agent, 8-22 parts sodium alginate, and 8-22 parts calcium chloride. In some specific embodiments of the present invention, the porous carrier comprises the following components in parts by weight: 10-20 parts oyster shell pretreatment agent, 50-60 parts chitosan pretreatment agent, 10-20 parts sodium alginate, and 10-20 parts calcium chloride.

[0038] In some embodiments of the present invention, the porous carrier is prepared by mixing the raw materials for preparing the porous carrier, granulating them, and then calcining them at 180-220°C.

[0039] In some embodiments of the present invention, the microorganisms include at least one of Bacillus megaterium, Bacillus licheniformis, Pseudomonas stearothermiae, or white-rot fungi; in some embodiments of the present invention, the microorganisms include Bacillus megaterium, Bacillus licheniformis, Pseudomonas stearothermiae, and white-rot fungi in a mass ratio of 1:(0.8~1.5):(0.8~1.5):(0.8~1.5).

[0040] In some embodiments of the present invention, the mass ratio of the porous carrier to the microorganisms is 1:(0.1~0.5); in some embodiments of the present invention, the mass ratio of the porous carrier to the microorganisms is any value of 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, or a range formed by any two of these values. In some specific embodiments of the present invention, the mass ratio of the porous carrier to the microorganisms is 1:(0.3~0.4).

[0041] In some embodiments of the present invention, the mass ratio of the core material to the calcium alginate coating layer is 1:(0.01~0.1). In some specific embodiments of the present invention, the mass ratio of the core material to the coating layer is 1:(0.06~0.09).

[0042] In some embodiments of the present invention, the mass ratio of the active calcium to the zinc oxide is 1:(4~7)×10. -7 In some specific embodiments of the present invention, the mass ratio of the active calcium to the zinc oxide is 1:(4.5~5.5)×10. -7 .

[0043] In some embodiments of the present invention, the oyster shell pretreatment agent is prepared by a method comprising the following steps: mixing zinc oxide with water to prepare a zinc oxide dispersion; mixing the zinc oxide dispersion with active calcium and drying to obtain the oyster shell pretreatment agent.

[0044] In some embodiments of the present invention, the concentration of the zinc oxide dispersion is 0.5~1.5 mg / L.

[0045] In some embodiments of the present invention, the ratio of the zinc oxide dispersion to the active calcium is 1 mL: (1~3) g.

[0046] In some embodiments of the present invention, the inorganic peroxyate includes at least one of potassium persulfate, sodium persulfate, or ammonium persulfate; in some specific embodiments of the present invention, the inorganic peroxyate is selected from potassium persulfate.

[0047] In some embodiments of the present invention, the mass ratio of chitosan to inorganic peroxide is 1:(0.1~0.5); in some specific embodiments of the present invention, the mass ratio of chitosan to inorganic peroxide is 1:(0.2~0.3).

[0048] In some embodiments of the present invention, the chitosan pretreatment agent is prepared by a method comprising the following steps: mixing an inorganic peroxide acid salt with water to prepare an inorganic peroxide acid salt solution; mixing the inorganic peroxide acid salt solution with chitosan and drying to obtain the chitosan pretreatment agent.

[0049] In some embodiments of the present invention, the concentration of the inorganic peroxyate solution is 0.5~1.5 mol / L.

[0050] In some embodiments of the present invention, the ratio of the inorganic peroxide solution to the chitosan is 1 mL: (0.5~1.5) g.

[0051] In some embodiments of the present invention, the mass ratio of the humic acid-based repair agent to the embedded fungal repair agent is 1:(0.8~3.5). In some specific embodiments of the present invention, the mass ratio of the humic acid-based repair agent to the embedded fungal repair agent is 1:(1~3); in some more specific embodiments of the present invention, the mass ratio of the humic acid-based repair agent to the embedded fungal repair agent is 1:(1.5~2.5).

[0052] This invention utilizes the loose and porous framework structure of oyster shells after high-temperature calcination and modified chitosan to provide a porous matrix for humic acid and microorganisms, preparing a combined physicochemical adsorption and microbial adsorption degradation remediation agent. This not only efficiently solves the problem of heavy metal pollution in soil, but also the heavy metal remediation agent has a stable structure and can be recycled after remediation, effectively removing heavy metals from the soil and preventing secondary pollution.

[0053] Specifically, the heavy metal remediation agent of the present invention has the following advantages: 1) Oyster shells are primarily composed of calcium carbonate, accounting for approximately 90%-95%, forming their hard main structure. After high-temperature calcination and hydration, oyster shells form porous active calcium, significantly increasing their ability to adsorb heavy metals, immobilize microorganisms, and improve soil conditions. Calcium carbonate, when calcined at high temperatures, decomposes into calcium oxide and carbon dioxide. The calcium oxide product is mixed with water and stirred to generate calcium hydroxide precipitate. The calcium hydroxide precipitate is then stirred with a zinc oxide dispersion and dried to obtain porous active calcium with a zinc oxide coating on its surface. The porous structure formed by high-temperature calcination of oyster shells increases the specific surface area, enhancing the adsorption capacity for heavy metals and organic pollutants, while also providing growth space for microorganisms. This invention requires placing the prepared heavy metal remediation agent in heavy metal-contaminated sediment, inevitably subjecting it to ultraviolet radiation and the coating of moist sediment. The effects of ultraviolet radiation on the wetted active calcium are mainly manifested in accelerating its oxidation reaction and inducing molecular chain breakage, leading to material performance degradation and embrittlement. Calcium hydroxide precipitate is placed in zinc oxide dispersion and stirred and mixed. During the drying process, zinc oxide is formed to coat the active calcium. On the one hand, zinc oxide blocks ultraviolet rays through physical reflection and scattering, which can maintain the overall stability of the material and ensure that the material remains intact and is easy to recycle. On the other hand, the introduction of zinc oxide can enhance the hardness of active calcium and optimize the surface properties of active calcium, which is beneficial to the adsorption of heavy metals.

[0054] 2) Chitosan is a natural biopolymer typically produced from raw materials such as shrimp and crab shells through decalcification and deproteinization to obtain chitin, followed by deacetylation. Using chitosan as a raw material allows for the rational utilization of some aquatic product waste resources, achieving a unified economic, ecological, and social benefit, which is conducive to sustainable development. The chitosan molecule contains functional groups such as amino and hydroxyl groups, which can interact with heavy metal ions, achieving their adsorption. Activating chitosan with inorganic peroxides (such as potassium persulfate) allows hydroxyl groups from sodium alginate to be grafted onto the chitosan, initiating subsequent grafting and copolymerization of chitosan with other monomers (such as sodium alginate) to form an interpenetrating network of macromolecules. This facilitates the distribution of humic acid and microorganisms within the network structure, further improving and enhancing its adsorption performance. The heavy metal remediation agent formed by calcined oyster shells and modified chitosan has a complex surface structure with numerous pores and good adsorption performance; the two can work synergistically to adsorb heavy metals. 3) Humic acid is formed from the decomposition and transformation of plant and animal remains (mainly plant remains) by microorganisms. Its basic structure consists of aromatic and aliphatic rings, with functional groups such as carboxyl, hydroxyl, carbonyl, quinone, and methoxy groups attached to the rings. The carboxyl, hydroxyl, and carbonyl groups in humic acid molecules can form chelates or complexes with heavy metal ions, reducing the solubility and migration of heavy metals in sediment. Adding humic acid to heavy metal remediation agents, in conjunction with other materials, allows for synergistic adsorption of heavy metals, resulting in efficient, rapid, and long-lasting treatment.

[0055] 4) Sodium alginate is a natural high-molecular-weight compound extracted from the cell walls of algae. It is a natural polysaccharide composed of abundant hydroxyl and carboxyl groups. Sodium alginate is readily soluble in water and has strong hydrophilicity. Upon absorbing water, it expands in volume, resulting in a viscous aqueous solution. On one hand, under the action of inorganic peroxides (such as potassium persulfate) as initiators, chitosan and sodium alginate cross-link to form an interpenetrating network of macromolecules, which is beneficial for the distribution of humic acid and microorganisms within the network structure. On the other hand, due to the viscous properties of sodium alginate, adding an appropriate amount during granulation can promote the agglomeration of powders, thereby improving granulation efficiency and yield.

[0056] 5) By controlling the pore size distribution and specific surface area through particle pore formation, the adsorption capacity for heavy metal ions is significantly improved, promoting the rapid stabilization of heavy metals in sediment by the heavy metal remediation agent through chelation, precipitation, and adsorption. Calcium chloride is added during the granulation process. After absorbing moisture, calcium chloride forms hydrates. These hydrates undergo further hydrolysis during vacuum sintering to generate calcium oxide, gradually forming a porous structure and increasing the porosity of the particles.

[0057] 6) Microorganisms degrade heavy metals in sediment through adsorption, reduction, transformation, and competition, effectively reducing the toxicity and mobility of heavy metals. Microorganisms adsorb and transform heavy metals through themselves and their metabolites, resulting in non-toxic and harmless products and rapid pollutant degradation. Immobilizing microorganisms in a porous carrier using calcium alginate encapsulation provides a relatively stable growth environment, mitigating the impact of environmental changes, reducing loss during heavy metal adsorption and degradation, enhancing microbial stability, and extending their lifespan.

[0058] 7) This invention's heavy metal remediation agent is based on both chemical and biological remediation methods. The synergistic effect of these two methods results in higher heavy metal removal efficiency and better efficacy. Through adsorption and precipitation, the agent reduces the bioavailability and migration capacity of heavy metals in sediment. Furthermore, the heavy metal remediation agent is granular, making it easy to landfill and recover during soil tillage after application to heavy metal-contaminated sediment. The loose sediment also enhances the adsorption efficiency of the agent. Therefore, this invention effectively reduces the concentration of heavy metals in sediment, treats polluted sediment, minimizes long-term impacts on the physicochemical properties of the sediment, and prevents secondary pollution.

[0059] The heavy metal remediation agent of this invention is prepared by a method comprising the following steps: Humic acid, oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate and calcium chloride are mixed, granulated and vacuum sintered to obtain humic acid-based repair agent. Oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate, and calcium chloride are mixed, granulated, and vacuum sintered to obtain a porous carrier. The porous carrier is mixed with a microbial solution to form a core material. Sodium alginate solution and calcium chloride solution are then added to react and generate a calcium alginate coating layer to obtain the embedded microbial remediation agent. The humic acid remediation agent is mixed with the embedded microbial remediation agent to obtain the heavy metal remediation agent.

[0060] In some embodiments of the present invention, the granulation step is as follows: mixing the mixture with water, extruding and granulating, and drying and shaping; in some specific embodiments of the present invention, the mass ratio of the mixture to water is (4~6):1; the drying and shaping temperature is 70~90℃; and the drying and shaping time is 8~12h.

[0061] In some embodiments of the present invention, the vacuum sintering temperature is 150~250℃; in some specific embodiments of the present invention, the vacuum sintering temperature is 180~220℃.

[0062] In some embodiments of the present invention, the vacuum sintering time is 2-3 hours; in some specific embodiments of the present invention, the vacuum sintering time is 2.3-2.7 hours.

[0063] In some embodiments of the present invention, the heating rate of the vacuum sintering is 10~20℃ / min; in some specific embodiments of the present invention, the heating rate of the vacuum sintering is 13~17℃ / min.

[0064] In some embodiments of the present invention, the vacuum sintering is carried out in a protective gas atmosphere; in some specific embodiments of the present invention, the protective gas includes at least one of nitrogen, argon or helium.

[0065] In some embodiments of the present invention, the humic acid-based remedial agent is a porous particle with a particle size of 2-3 cm and a pore size of 5-100 μm.

[0066] In some embodiments of the present invention, the mass concentration of the microbial solution is 5-12%; in some specific embodiments of the present invention, the mass concentration of the microbial solution is 8-10%.

[0067] In some embodiments of the present invention, the mass concentration of the sodium alginate solution is 2-6%; in some specific embodiments of the present invention, the mass concentration of the sodium alginate solution is 3-5%.

[0068] In some embodiments of the present invention, the mass concentration of the calcium chloride solution is 2-6%; in some specific embodiments of the present invention, the mass concentration of the calcium chloride solution is 3-5%.

[0069] In some embodiments of the present invention, the porous carrier is a porous particle with a pore size of 5~100μm.

[0070] In some embodiments of the present invention, the particle size of the embedded bacterial repair agent is 0.6~1.5cm.

[0071] In some embodiments of the present invention, the heavy metals contained in the sediment of the water body include at least one of cadmium, mercury, arsenic or lead.

[0072] In some embodiments of the present invention, the repair time is 20 to 40 days; after the repair is completed, the heavy metal repair agent is recycled.

[0073] In some embodiments of the present invention, the depth of the heavy metal remediation agent in the bottom sediment of the water body is 0~30cm.

[0074] In some embodiments of the present invention, the slow-release sediment remediation agent comprises the following components in parts by weight: 30-40 parts modified attapulgite, 18-25 parts composite microbial agent, 15-20 parts nano hydroxyapatite, 8-12 parts straw charcoal, 5-8 parts binder, 7-10 parts humic acid material, 3-6 parts calcium carbonate, 2-4 parts antioxidant, and 3-6 parts water. The modified attapulgite is obtained by modifying attapulgite with acid and surfactant.

[0075] The slow-release sediment remediation agent of this invention can achieve synergistic removal of multiple pollutants, with good removal effect, strong environmental adaptability, and high ecological safety. The slow-release sediment remediation agent of this invention includes a main functional component, auxiliary functional components, and a stabilizer; the main functional component includes modified attapulgite, composite microbial inoculant, and nano-hydroxyapatite; the auxiliary functional components include straw charcoal, binder, and humic acid materials; the modified attapulgite is obtained by modifying attapulgite with acid and surfactants; the composite microbial inoculant includes Pseudomonas, Bacillus, white-rot fungi, composite nitrifying bacteria, and polyphosphate-accumulating bacteria.

[0076] This invention utilizes modified attapulgite, composite microbial agents, nano-hydroxyapatite, and other components to work together to achieve the synergistic and efficient removal of heavy metals, organic pollutants, and organic nitrogen and phosphorus from contaminated sediments through a combination of physical adsorption, chemical fixation, and biodegradation. Furthermore, it improves the microenvironment and structure of the sediments, enhances environmental adaptability, and provides high ecological safety.

[0077] In some embodiments of the present invention, the acid solution includes at least one of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0078] In some embodiments of the present invention, the surfactant comprises hexadecyltrimethylammonium bromide.

[0079] In some embodiments of the present invention, the specific surface area of ​​the modified attapulgite soil is 300-400 m². 2 / g.

[0080] In some embodiments of the present invention, the particle size of the modified attapulgite is ≤20μm.

[0081] Specifically, attapulgite is a natural adsorbent with a large specific surface area, good internal channels, and ion exchange capacity. Modification can further increase its specific surface area; its porous structure can adsorb heavy metals and inorganic phosphorus, while its hydrophobic groups adsorb organic pollutants, and it also provides an attachment carrier for microorganisms.

[0082] In some embodiments of the present invention, the composite microbial agent includes Pseudomonas, Bacillus, white-rot fungi, composite nitrifying bacteria, and polyphosphate-accumulating bacteria.

[0083] In some embodiments of the present invention, the composite microbial agent comprises Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria in a weight ratio of (1.5-2.5):(1.5-2.5):(0.8-1.2):(1.5-2.5):1. In some embodiments of the present invention, the mass ratio of Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria in the composite microbial agent is (1.8-2.2):(1.8-2.2):(0.9-1.1):(1.8-2.2):1. In some embodiments of the present invention, the mass ratio of Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria in the composite microbial agent is 2:2:1:2:1.

[0084] Pseudomonas secretes chelating enzymes to enhance heavy metal adsorption; Bacillus degrades polycyclic aromatic hydrocarbons; Pseudomonas and Bacillus secrete organic acids to promote the dissolution of inorganic phosphorus; white-rot fungi degrade polychlorinated biphenyls (PCBs); nitrifying bacteria and nitrifying bacteria (such as at least one of Nitrosomonas, Nitrospirillum, and Nitrococcus, and at least one of Nitrobacter, Nitrospirillum, and Nitrocystis) can convert ammonia nitrogen into nitrate nitrogen, which is easier for aquatic plants to absorb and utilize; polyphosphate-accumulating bacteria absorb excess phosphorus while simultaneously degrading organic phosphorus. Through the combined action of Pseudomonas, Bacillus, white-rot fungi, complex nitrifying bacteria, and polyphosphate-accumulating bacteria, the degradation of inorganic and organic phosphorus, the adsorption of heavy metals, and the degradation of organic pollutants are achieved.

[0085] In some embodiments of the present invention, the particle size of the nano-hydroxyapatite is 50-100 nm.

[0086] In some embodiments of the present invention, the purity of the nano-hydroxyapatite is ≥98%.

[0087] Specifically, nano-hydroxyapatite reacts with heavy metals to form stable metal phosphate salts, and can adjust the pH of the sediment to 6.5-7.5, which is suitable for microbial growth. It can also adsorb inorganic phosphorus and work synergistically with polyphosphate-accumulating bacteria to remove phosphorus.

[0088] In some embodiments of the present invention, the straw charcoal is obtained by anaerobic carbonization of corn straw.

[0089] In some embodiments of the present invention, the anaerobic carbonization temperature is 400-500°C, and the anaerobic carbonization time is 3-4 hours.

[0090] In some embodiments of the present invention, the pore size of the straw charcoal is 2-50 nm.

[0091] Specifically, straw charcoal can help adsorb organic pollutants and nitrogen and phosphorus, provide carbon sources for microorganisms, promote nitrification and denitrification, improve denitrification efficiency, improve sediment aeration, and increase dissolved oxygen to more than 3 mg / L.

[0092] In some embodiments of the present invention, the adhesive comprises sodium alginate.

[0093] In some embodiments of the present invention, the viscosity of the adhesive is 200-300 mPa·s at 25°C.

[0094] Specifically, sodium alginate, as a food-grade binder, can improve the distribution uniformity of slow-release sediment remediation agents, reduce loss rate, promote sediment colloidal aggregation, improve sediment structure, and simultaneously provide nutrients for microorganisms, increasing the survival rate of the inoculant. Meanwhile, sodium alginate reacts with Ca... 2+ An "ionic cross-linking reaction" occurs, forming a three-dimensional network structure that can bind powders (such as microbial agents and straw charcoal) together and encapsulate active ingredients such as composite microbial agents and straw charcoal. Ultimately, it forms stable particles that are "insoluble in water but can slowly swell when exposed to water." When added to the bottom sediment, it will not collapse instantly and can gradually release functional components, which can extend the remediation cycle. This ensures the long-term effectiveness of the slow-release sediment remediation agent and optimizes the microenvironment.

[0095] In some embodiments of the present invention, the humic acid material includes at least one of humic acid, potassium humate, and sodium humate.

[0096] Specifically, humic acid materials can form stable complexes with heavy metals, adjusting the carbon-to-nitrogen ratio (C / N) of the sediment to 15-20, which is suitable for microbial growth. Simultaneously, humic acid materials, in synergy with calcium carbonate in the stabilizer, can maintain macroscopic pH stability in the sediment. Furthermore, humic acid materials can interact with organic pollutants such as pesticides, herbicides, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) through hydrophobic adsorption, hydrogen bonding, charge transfer, and coordination exchange, thereby influencing the migration, transformation, and biodegradation of organic pollutants in the sediment.

[0097] In some embodiments of the present invention, the stabilizer includes calcium carbonate and antioxidants.

[0098] In some embodiments of the present invention, the stabilizer comprises 3-6 parts calcium carbonate and 2-4 parts antioxidant by weight.

[0099] In some embodiments of the present invention, calcium carbonate can stabilize the pH of the sediment (maintaining it at 5.0-8.5), avoiding drastic pH fluctuations that could affect microbial activity. At the same time, it reacts with sulfate ions to generate calcium sulfate, reducing sulfide production and lowering the degree of blackening and odor.

[0100] In some embodiments of the present invention, the antioxidant includes vitamin C.

[0101] Specifically, the vitamin C is food grade. As an antioxidant, it can inhibit the toxicity of heavy metals, improve the survival rate of polyphosphate-accumulating bacteria in cadmium-contaminated sediment, promote microbial activity, and prevent secondary pollution caused by the oxidation of reducing substances in the sediment.

[0102] The slow-release sediment remediation agent of this invention has the following advantages: (1) This invention focuses on sediments contaminated with a complex mixture of heavy metals, organic pollutants, and nitrogen and phosphorus, and achieves two core objectives through the synergistic effect of physical adsorption, chemical fixation, and biodegradation: Highly efficient and synergistic removal of multiple pollutants: Simultaneously reduces heavy metals, degrades organic pollutants (PAHs), and removes nitrogen and phosphorus (containing organic nitrogen / phosphorus), ensuring that core pollutants meet control standards within 60 days; Improving the microenvironment and structure of sediment: adjusting pH to neutral, increasing dissolved oxygen, reducing black odor (sulfides), optimizing sediment porosity and colloidal stability, and creating conditions for biological survival.

[0103] Ultimately, it achieves a synergistic effect of "1+1+1>3", which not only solves the pain point of traditional technologies such as "single pollution remediation and ecological damage", but also achieves the goal of efficient, thorough and safe sediment remediation through the mutual reinforcement of various functions.

[0104] (2) The components of the slow-release sediment remediation agent of the present invention do not act independently, but form a complete closed loop of "adsorption-fixation-degradation-optimization-activation"; the physical components (modified attapulgite, straw charcoal) are responsible for "capturing" pollutants, the chemical components (nano-hydroxyapatite) are responsible for "fixing" pollutants, and the biological components (bacterial agents) are responsible for "degrading" pollutants; the auxiliary components and stabilizers eliminate the limitations of each component by optimizing pH, oxygen supply and nutrient conditions.

[0105] (3) The raw materials of the slow-release sediment remediation agent of this invention are mainly natural minerals and agricultural waste straw, which are low in cost, require no special equipment, and have strong product stability. In addition, the use of sodium alginate as a binder can improve the dispersibility of the slow-release sediment remediation agent, reduce the loss rate, promote sediment colloid aggregation, and slowly release microbial protection and active ingredients, which can complete the repair within a certain period of time and can continue to work to consolidate the effect. The slow-release sediment remediation agent of this invention is prepared by a method including the following steps.

[0106] Specifically, the preparation method of the slow-release sediment remediation agent includes the following steps: The raw material components are mixed, granulated, and then obtained.

[0107] In some embodiments of the present invention, mixing is carried out in a twin-screw mixer.

[0108] In some embodiments of the present invention, the mixing speed is 300-400 r / min, the temperature is 25-30℃, and the time is 30-40 min.

[0109] In some embodiments of the present invention, the granulation process further includes a drying process.

[0110] In some embodiments of the present invention, the particle size of the particles obtained after granulation is 1-3 mm.

[0111] In some embodiments of the present invention, the drying temperature is 60-70°C and the drying time is 2-3 hours.

[0112] In some embodiments of the present invention, the method for preparing the modified attapulgite includes the following steps: mixing attapulgite with acid solution and activating it; obtaining activated attapulgite, and then mixing it with a surfactant to obtain the final product.

[0113] In some embodiments of the present invention, the solid-liquid ratio of the attapulgite clay and the acid is 1 kg: (4-6) L; for example, 1 kg: 2 L, 1 kg: 2.5 L, 1 kg: 3 L, 1 kg: 3.5 L, 1 kg: 4 L, etc.

[0114] In some embodiments of the present invention, the mass fraction of the acid solution is 5-8%; for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, etc.

[0115] In some embodiments of the present invention, the activation temperature is 30-40°C, and the activation time is 2-3 hours; stirring is performed during the activation process.

[0116] In some embodiments of the present invention, the activated material is filtered and washed with deionized water until the pH reaches 6.8-7.2, and then dried.

[0117] In some embodiments of the present invention, the drying temperature is 80-100°C and the drying time is 4-6 hours.

[0118] In some embodiments of the present invention, the solid-liquid ratio of the activated attapulgite clay and the surfactant is 1 kg: (2-4) L; for example, 1:2, 1:2.5, 1:3, 1:3.5, 1:4.

[0119] In some embodiments of the present invention, the surfactant has a mass fraction of 2-3%; for example, 2%, 2.5%, 3%, etc.

[0120] In some embodiments of the present invention, the activated attapulgite clay and the surfactant are stirred during the mixing process, the stirring temperature is 50-60°C, and the stirring time is 4-5 hours.

[0121] In some embodiments of the present invention, the process of stirring is further included by filtering, drying, and pulverizing to a particle size ≤20μm.

[0122] In some embodiments of the present invention, the preparation process of the composite microbial agent includes the following steps: Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria were mixed to obtain a mixed bacterial cell. Then, a protective agent was added, and the mixture was freeze-dried under vacuum to obtain the final product.

[0123] In some embodiments of the present invention, the protective agent includes at least one of aseptic skim milk powder and glycerin.

[0124] In some embodiments of the present invention, the amount of the protective agent accounts for 8-12% of the total weight of the mixed bacterial cells; for example, 8%, 8.5%, 9%, 9.5%, 10%, 10.5%, 11%, 11.5%, 12%, etc.

[0125] In some embodiments of the present invention, the preparation method of the nano-hydroxyapatite includes the following steps: mixing calcium salt, phosphate and solvent; adjusting pH to alkaline, reacting, and obtaining the nano-hydroxyapatite.

[0126] In some embodiments of the present invention, the calcium salt includes at least one of calcium nitrate, calcium chloride, and calcium carbonate.

[0127] In some embodiments of the present invention, the phosphate includes at least one of diammonium hydrogen phosphate, disodium hydrogen phosphate, and diammonium dihydrogen phosphate.

[0128] In some embodiments of the present invention, the molar ratio of Ca and P in the calcium salt and phosphate is (1.6-1.7):1; for example, 1.6:1, 1.65:1, 1.67:1, 1.7:1.

[0129] In some embodiments of the present invention, the solvent includes water.

[0130] In some embodiments of the present invention, after mixing calcium salt, phosphate, and solvent, the pH is adjusted to 9.0-10.0.

[0131] In some embodiments of the present invention, during the preparation of the nano-hydroxyapatite, the reaction temperature is 60-70°C and the reaction time is 3-4 hours.

[0132] In some embodiments of the present invention, the precipitate is collected by centrifugation after the reaction, washed, dried, pulverized, and then obtained.

[0133] In some embodiments of the present invention, the washing is performed 3-4 times.

[0134] In some embodiments of the present invention, the drying temperature is 100-110°C and the drying time is 8-10 hours.

[0135] In some embodiments of the present invention, the pulverization is described as 50-100 nm.

[0136] In some embodiments of the present invention, the dosage of the heavy metal remediation agent is 100-2000 g / m³. 2 In some embodiments of the present invention, the dosage of the heavy metal remediation agent is 100 g / m³. 2 200g / m 2 300g / m 2 400g / m 2 500g / m 2 600g / m 2 700g / m 2 800g / m 2 900g / m 2 1000g / m 2 1100g / m 2 1200g / m 21300g / m 2 1400g / m 2 1500g / m 2 1600g / m 2 1700g / m 2 1800g / m 2 1900g / m 2 2000g / m 2 The range of values ​​formed by any one of the values ​​in the range, or any two of them.

[0137] In some embodiments of the present invention, the heavy metal remediation agent is applied every 5-7 days until the heavy metal content in the sediment of the water body is lower than the risk screening value for agricultural land soil pollution. The risk screening value for agricultural land soil pollution requires that the cadmium content in the sediment does not exceed 0.6 mg / kg, mercury does not exceed 0.6 mg / kg, arsenic does not exceed 25 mg / kg, and lead does not exceed 140 mg / kg.

[0138] In some embodiments of the present invention, the dosage of the slow-release sediment remediation agent is 100-2000 g / m³. 2 In some embodiments of the present invention, the dosage of the slow-release sediment remediation agent is 100 g / m³. 2 200g / m 2 300g / m 2 400g / m 2 500g / m 2 600g / m 2 700g / m 2 800g / m 2 900g / m 2 1000g / m 2 1100g / m 2 1200g / m 2 1300g / m 2 1400g / m 2 1500g / m 2 1600g / m 2 1700g / m 2 1800g / m 2 1900g / m 2 2000g / m 2 The range of values ​​formed by any one of the values ​​in the range, or any two of them.

[0139] In some embodiments of the present invention, the slow-release sediment remediation agent is applied once every 8-10 days until ΣPAHs do not exceed 4000 μg / kg, total nitrogen content does not exceed 1000 mg / kg, and total phosphorus does not exceed 400 mg / kg.

[0140] Step S3 of this invention involves first introducing algae-controlling microorganisms to eliminate existing cyanobacteria, then introducing photosynthetic bacteria and EM bacteria to promote the growth of single-celled algae, and finally introducing zooplankton to feed on the resulting single-celled algae. This avoids the situation where severe pollution causes zooplankton death, or where cyanobacteria clusters are too large for zooplankton to feed on, thus maximizing the role of zooplankton and achieving a triple synergistic effect of algae control, pollution reduction, and improved water transparency. Furthermore, this method eliminates the need for domesticated zooplankton to feed on cyanobacteria and improve water transparency.

[0141] In some embodiments of the present invention, the aquatic animals include at least one of fish, shrimp, snails, and shellfish.

[0142] In some embodiments of the present invention, the fish is selected from at least one of carnivorous fish and filter-feeding fish.

[0143] In some embodiments of the present invention, the total number of fish released is 500-700 per 10,000 m³. 2 .

[0144] In some embodiments of the present invention, the average weight of the fish is 200-300g / fish.

[0145] In some embodiments of the present invention, the fish is selected from at least one of mandarin fish, snakehead fish, perch, and silver carp.

[0146] In some embodiments of the present invention, the fish species are mandarin fish, snakehead fish, perch and silver carp in a ratio of 1:(1-2):(1-3):(1-3).

[0147] In some embodiments of the present invention, the total amount of shrimp released is 100-150 kg / 10,000 m³. 2 .

[0148] In some embodiments of the present invention, the average length of the shrimp is 2-3 cm per shrimp.

[0149] In some embodiments of the present invention, the shrimp species are selected from at least one of green shrimp and black-shelled shrimp.

[0150] In some embodiments of the present invention, the shrimp are selected from green shrimp and black shrimp in a ratio of 1:(2-4).

[0151] In some embodiments of the present invention, the total amount of snails released is 150-200 kg / 10,000 m³. 2 .

[0152] In some embodiments of the present invention, the average length of the snail is 1-3 cm per snail.

[0153] In some embodiments of the present invention, the snail is selected from at least one of the following: *Triplophysa gracilis*, *Triplophysa radiata*, *Triplophysa squarrosa*, and *Triplophysa squarrosa*.

[0154] In some embodiments of the present invention, the snails are of the following species in a number ratio of (3-5):(1-2):(1-3):1: *Bellamya chinensis*, *Bellamya radiata*, *Bellamya squarrosa*, and *Bellamya squarrosa*.

[0155] In some embodiments of the present invention, the total amount of shellfish released is 80-120 kg / 10,000 m³. 2 .

[0156] In some embodiments of the present invention, the average length of the shellfish is 2-5 cm per shellfish.

[0157] In some embodiments of the present invention, the shellfish is selected from at least one of the following: clam, razor clam, sail clam, and crown clam.

[0158] In some embodiments of the present invention, the number ratio of the shellfish is 1:(1-2):(1-2):(1-2) for mussels, razor clams, sail mussels and crown mussels.

[0159] The beneficial effects of this invention are as follows: By using slow-release sediment remediation agents and heavy metal remediation agents, this invention achieves in-situ treatment without the need for dredging and off-site disposal of sludge; after reducing pollutants in the sediment, aquatic plants can be directly planted in the sediment for aquatic ecological restoration; then, algae-controlling microorganisms, photosynthetic bacteria, EM bacteria, and zooplankton are sequentially introduced, working synergistically to effectively improve water transparency, eliminating the need for domesticated zooplankton to feed on blue-green algae and improve water transparency; then, aquatic plant species are matched according to water depth and climate to optimize planting methods, achieving long-term and stable water body restoration, and the biological water body restoration does not produce secondary pollution.

[0160] In this invention, slow-release sediment remediation agents and heavy metal remediation agents are used to reduce heavy pollution and organic matter in sediment. After sediment pollution is reduced, algae control and water pollution removal are carried out to improve water transparency. Then, aquatic plants are planted and finally aquatic animals are introduced to build an aquatic ecosystem and achieve the purpose of water ecological restoration. Detailed Implementation

[0161] The following examples provide a more detailed description of the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are methods that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0162] The material information used in the following embodiments and comparative examples is as follows: Staphylococcus epidermidis ( Staphylococcus epidermidis ): ATCC 35984 (strain RP62A); Flavobacterium tumefaciens ( Flavobacterium branchiophilum ): ATCC 35035; Photosynthetic bacteria: Rhodophyton floccosum ( Rhodobacter sphaeroides ): ATCC 49419; EM bacteria were purchased from Foster Biotechnology (Taizhou) Co., Ltd., product code FST065611211.YD; Bacillus megaterium ( Bacillus megaterium ):ATCC 14581; Bacillus licheniformis ( Bacillus licheniformis ):ATCC 13438; Pseudomonas stearothermia ( Pseudomonas stutzeri ):ATCC 17588; White-rot fungi: *Phanerochaete chrysosporium* ( Phanerochaete chrysosporium ):ATCC 24725; Pseudomonas: Pseudomonas aeruginosa ( Pseudomonas aeruginosa ):ATCC 15442; Bacillus: Bacillus pumilus ( Bacillus pumilus ):ATCC 14884; Nitrifying bacteria: Nitrifying bacteria ( Nitrobacter sp. ):ATCC 51921; Nitrifying bacteria: Nitrosomonas cerevisiae (European nitrosomonas) Nitrosomonas europaea ):ATCC 25978; Polyphosphate-accumulating bacteria: Acinetobacter baumannii ( Acinetobacter baumannii ):ATCC 17978.

[0163] Example 1 This example provides an ecological restoration method for severely polluted water bodies with sediment, specifically a heavily polluted riverbed (neutral sediment + room temperature environment). The specific steps are as follows: 1. A polluted and odorous river in a city was selected. The sediment thickness was 0.6 m, pH=7.2, and the ambient temperature was 18-25℃. Initial sediment parameters were: cadmium 2.8 mg / kg, mercury 0.8 mg / kg, arsenic 32 mg / kg, lead 215 mg / kg, ΣPAHs 6800 μg / kg, total nitrogen 1950 mg / kg, and total phosphorus 850 mg / kg. The water transparency was 0.4 m, dissolved oxygen was 1.8 mg / L, and the water was dark green (blue-green algae bloom).

[0164] 2. Implementation Steps (1) Reduction of sediment pollution First, reduce heavy metal pollution: Add a heavy metal remediation agent to the bottom sediment of the water body at a dosage of 300g / m³. 2 The substance was applied once every 6 days, for a total of 3 applications. Five days after the third application, the heavy metal content was tested and found to be below the screening values ​​(test results: cadmium 0.52 mg / kg, mercury 0.48 mg / kg, arsenic 22 mg / kg, lead 132 mg / kg).

[0165] Further reduce organic matter and nutrients: Add slow-release sediment remediation agent at a dosage of 400g / m³. 2 The pesticide was applied once every 9 days, for a total of 3 applications. Eight days after the third application, testing was conducted, and the results were: ΣPAHs = 3200 μg / kg, total nitrogen = 920 mg / kg, and total phosphorus = 380 mg / kg, meeting the standards.

[0166] (2) Improved water transparency First, add algae-controlling microorganisms (Staphylococcus: Flavobacterium tumefaciens = 1:1, dry weight ratio of bacterial powder), at a dosage of 90g / m³. 3 The water was released once every 3 days, for a total of 2 times, and the water changed from dark green to yellowish-green.

[0167] Then, photosynthetic bacteria and EM bacteria (volume ratio 1:3) are added at a rate of 280 mL / m³. 3 One delivery completed.

[0168] Then release cladocerans (Daphnia macrocarpa) at a rate of 140 g / m³. 3 The treatment was completed in one go. After 15 days, the water transparency increased to 1.3m.

[0169] (3) Aquatic plant cultivation Water depth < 0.5m: Plant emergent plants such as sweet flag (Acorus calamus) at a density of 200 plants / m². 2 .

[0170] Water depth 0.5-1.5m: Plant submerged plants Vallisneria natans and Vallisneria nigra in a 1:1 ratio, at a density of 200 plants / m². 2 .

[0171] Water depth 1.5-2.5m: Plant submerged plants *Hydrilla verticillata* and *Potamogeton crispus* in a 1:1 ratio, at a density of 230 plants / m². 2 .

[0172] (4) Release of aquatic animals After the vegetation coverage reaches 85%, aquatic animals will be introduced: mandarin fish, snakehead fish, bass, and silver carp (in a ratio of 1:1:2:2), with a total of 600 fish per 10,000 m³.2 (The average weight of the fish is approximately 250g / fish, and the stocking density is 10,000m³ / fish.) 2 600 shrimp were released; green shrimp and black shrimp (ratio 1:3), total stocking volume was 120 kg / 10,000 m³. 2 (The average length of the shrimp is 2-3cm / shrimp, and the stocking density is 10,000m²) 2 120 kg was released); the species included *Bellamya acuminata*, *Triplophysa acuminata*, *Triplophysa acuminata*, and *Triplophysa acuminata* (in a ratio of 4:1:2:1), with a total release of 180 kg / 10,000 m². 2 (The average length of the snail is 1-3cm / snail); the total stocking ratio of clam, razor clam, sail clam, and crown clam is 1:1:1:1, with a total stocking volume of 100kg / 10,000m² (the average length of the clam is 2-5cm / snail).

[0173] 3. Repair effect Sixty days after remediation using the above method, testing was conducted. The results were as follows: cadmium in the sediment was 0.38 mg / kg, mercury 0.32 mg / kg, arsenic 18 mg / kg, and lead 88 mg / kg (all better than the screening values ​​for agricultural land soil pollution risk); ΣPAHs = 850 μg / kg, total nitrogen = 680 mg / kg, and total phosphorus = 220 mg / kg; water transparency was 1.8 m, dissolved oxygen was 4.2 mg / L, and cyanobacteria density was <10. 4 Cells / L; aquatic plant survival rate 92%; aquatic animal survival rate 98%; the aquatic ecosystem is stable and there is no black and odorous phenomenon.

[0174] The heavy metal remediation agent used in this example was prepared using the following method, with the specific steps as follows: S1. Preparation of oyster shell pretreatment agent (1) After washing and drying the oyster shells with water, put them into a crusher for simple crushing. The crushed oyster shells are 3-5cm in size. (2) The crushed oyster shells were placed in a muffle furnace and calcined under air conditions. The heating rate was 15℃ / min, the calcination temperature was 800℃, and the calcination time was 1h. (3) The calcined oyster shells were first allowed to cool naturally and then mechanically cooled. The calcined oyster shells were allowed to cool naturally for 1.5 hours, and then mechanically cooled to room temperature at a cooling rate of 15℃ / min. Mechanical cooling is an artificial forced cooling method relative to natural cooling. It refers to the process of actively controlling the cooling rate and enhancing heat exchange efficiency through special mechanical equipment (such as a cooler) to allow the calcined oyster shells to cool down to room temperature quickly and evenly under controllable conditions.

[0175] (4) Put the cooled oyster shells into a crusher and crush them to 100 mesh; (5) React the oyster shell powder (main component is calcium oxide) from (4) with deionized water at a mass ratio of 3.11:1 to generate calcium hydroxide precipitate. Take the filtered calcium hydroxide precipitate (active calcium). (6) Take 1g of zinc oxide nanoparticles and dilute with deionized water to 1L, then use an ultrasonic disperser at 250W for 1h to prepare a 1g / L zinc oxide stock solution. Take 1mL of zinc oxide stock solution and dilute with deionized water to 1L, then use an ultrasonic disperser at 250W for 1h to prepare a 1mg / L zinc oxide dispersion for later use. (7) Place the calcium hydroxide precipitate in a 1 mg / L zinc oxide dispersion and mix them at a ratio of 2 g: 1 mL. Stir in a stirrer for 0.5 h at a stirring speed of 100 r / min. Dry at 70 °C for 2.5 h. After drying, dry in a dryer at 100 °C. After drying, crush and sieve to 100 mesh in a pulverizer to prepare oyster shell pretreatment agent for later use.

[0176] S2, preparation of chitosan pretreatment agent (1) Prepare a 1.0 mol / L potassium persulfate aqueous solution by dissolving 270.32 g of potassium persulfate powder and then diluting it with deionized water to a final volume of 1 L. (2) Add chitosan to potassium persulfate aqueous solution. Mix potassium persulfate aqueous solution and chitosan at a ratio of 1 mL: 1 g. Stir in a stirrer for 30 min at a stirring speed of 100 r / min. After stirring, place in a constant temperature box and shake at 25 °C and 110 r / min for 12.5 h. Filter and dry the filter residue in a dryer at 55 °C. After drying, crush and sieve to 100 mesh in a pulverizer to prepare chitosan pretreatment agent for later use.

[0177] S3, Preparation of Humic Acid-Based Repair Agents (1) Take 10 parts of humic acid, 35 parts of oyster shell pretreatment agent, 35 parts of chitosan pretreatment agent, 10 parts of sodium alginate and 10 parts of calcium chloride powder by mass, put them in a stirrer and stir for 1 hour at a stirring speed of 100 r / min to obtain a mixed powder. (2) The mixed powder in (1) is put into the granulator. Deionized water is sprayed out in the granulator in the form of spray. The deionized water and the mixed powder are mixed evenly at a mass ratio of 1:5 for 2.5 hours. After the granulator extrudes elliptical particles of 2-3 cm, it is preliminarily dried and shaped under the action of its hot air circulation system. The drying and shaping temperature is 80℃ and the drying time is 10 hours. (3) Allow the dried and shaped granules from (2) to cool naturally to room temperature; (4) The cooled particles from (3) are placed in a tube furnace and inert gas nitrogen or argon is introduced. The heating rate is 15℃ / min, the vacuum sintering temperature is 200℃, and the sintering time is 2.5h to produce porous particles with a pore size of about 5-100μm. (5) The sintered particles from (4) are first cooled naturally and then mechanically cooled. After natural cooling for 45 minutes, they are then mechanically cooled to room temperature at a cooling rate of 10℃ / min to prepare a humic acid-based repair agent for later use.

[0178] S4. Preparation of Embedded Bacterial Repair Agent (1) Take 20 parts of oyster shell pretreatment agent, 60 parts of chitosan pretreatment agent, 10 parts of sodium alginate and 10 parts of calcium chloride powder by mass, put them in a stirrer and stir for 1 hour at a stirring speed of 100 r / min to obtain mixed powder. (2) The mixed powder in (1) is put into the granulator. Deionized water is sprayed out in the granulator in the form of spray. The deionized water and the mixed powder are mixed evenly at a mass ratio of 1:5 for 2.5 hours. After the granulator extrudes elliptical particles of 0.5-1cm, it is preliminarily dried and shaped under the action of its hot air circulation system. The drying and shaping temperature is 80℃ and the drying time is 10 hours. (3) Allow the dried and shaped granules from (2) to cool naturally to room temperature; (4) The cooled particles from (3) are placed in a tube furnace and inert gas nitrogen or argon is introduced. The heating rate is 15℃ / min, the vacuum sintering temperature is 200℃, and the sintering time is 2.5h to produce porous particles with a pore size of about 5-100μm. (5) The sintered particles from (4) are first allowed to cool naturally and then mechanically cooled. After natural cooling for 45 minutes, they are then mechanically cooled to room temperature at a rate of 10℃ / min. (6) Microbial strains (Bacillus megaterium, Bacillus licheniformis, Pseudomonas stearothermiae, and white-rot fungi sludge in a mass ratio of 1:1:1:1) were placed in sterile fermentation medium for expansion culture. The fermentation broth was centrifuged, the supernatant was discarded, and the sludge was collected for later use. The centrifugation speed was 4000 rpm and the centrifugation time was 4 min. (7) Take the bacterial mud from (6) and mix it with sterile water at a mass ratio of 1:15 to obtain microbial liquid; (8) Take (5) particles and add them to (7) microbial solution at a mass ratio of 1:4, and let them adsorb for 4 hours; (9) Sodium alginate and sterile water are mixed at a mass ratio of 1:25, heated to dissolve, and then cooled to room temperature to obtain a 4% sodium alginate solution; calcium chloride powder and sterile water are stirred and dissolved at a mass ratio of 1:25 to obtain a 4% calcium chloride solution. (10) Add 4% sodium alginate solution to (8) at a mass ratio of 2:1 and mix for 1.5 h. Use a conveying device to drop the particles containing the mixture into 4% calcium chloride solution and let stand for 2.5 h to obtain embedded bacterial repair agent with a particle size of 0.6-1.5 cm. After washing the embedded bacterial repair agent with sterile water, store it in a refrigerator at 4℃ for later use.

[0179] S5, Preparation of Heavy Metal Repair Agent The humic acid-based remedial agent obtained in step S3 and the encapsulated fungal remedial agent prepared in step S4 are mixed evenly at a mass ratio of 1:2 to obtain a heavy metal remedial agent.

[0180] The slow-release sediment remediation agent used in this example is composed of the following raw materials: 35 parts modified attapulgite, 20 parts compound microbial agent, 18 parts nano hydroxyapatite, 10 parts straw charcoal, 6 parts sodium alginate, 8 parts sodium humate, 4 parts calcium carbonate, 3 parts vitamin C, and 3 parts deionized water.

[0181] The compound microbial agent is made by mixing mixed microbial bodies and aseptic skim milk powder in a mass ratio of 100:10. The mixed microbial bodies are: Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria and polyphosphate-accumulating bacteria in a weight ratio of 2:2:1:2:1. The compound nitrifying bacteria are composed of nitrifying bacteria and nitrite-oxidizing bacteria in a weight ratio of 1:1.

[0182] The slow-release sediment remediation agent used in this example was prepared using the following method, with the specific steps as follows: All raw materials except deionized water were added to a twin-screw mixer, which was set to a speed of 350 r / min and a temperature of 28℃ for 35 min. Deionized water was sprayed through a spraying device at the same time. Under the shearing and extrusion action of the screws inside the machine, the materials and sodium alginate were fully kneaded to form a "plastic mud-like material". The mixed material was then fed into a granulator and extruded to form a particle size of 2 mm (controlled by a screen). The granules were then placed in a 65℃ forced-air drying oven and dried for 2.5 h. After cooling to room temperature, the granules were packaged to obtain a slow-release sediment remediation agent.

[0183] The preparation process of modified attapulgite is as follows: (1) Take 10 kg of natural attapulgite clay (particle size ≤ 50 μm), add 50 L of 5 wt% hydrochloric acid solution (solid-liquid ratio 1 kg: 5 L), and activate it by stirring at 150 r / min for 2.5 h under constant temperature water bath conditions at 35 ℃. After activation, filter it using a plate and frame filter press, collect the filter residue, and wash it repeatedly with deionized water until the pH of the filtrate is 6.8-7.2 (detected with a precision pH meter). Place the washed filter residue into a forced-air drying oven and dry it at 90 ℃ for 5 h. (2) Add 30L of a 2.5% hexadecyltrimethylammonium bromide (CTMAB) aqueous solution (solid-liquid ratio 1kg:3L) to the dried attapulgite and modify it by stirring at 200r / min for 4.5h in a constant temperature water bath at 55℃. After modification, filter again, collect the filter residue, dry it at 85℃ for 4h, and pulverize it with an ultra-micro pulverizer to a particle size ≤20μm (detected by a laser particle size analyzer) to obtain modified attapulgite.

[0184] The preparation process of compound microbial agents is as follows: Pseudomonas culture: Take 10L of LB medium (10g / L tryptone, 5g / L yeast extract, 10g / L NaCl), sterilize it, inoculate with Pseudomonas inoculum, and culture in a shaker at 30℃ and 180r / min for 24h. Bacillus culture: Take 10L of beef extract peptone medium (beef extract 3g / L, peptone 10g / L, NaCl 5g / L), sterilize it, inoculate with Bacillus strain, and culture in a shaker at 32℃ and 150r / min for 20h. Culture of white rot fungi: Take 5L of PDA medium (potato 200g / L, glucose 20g / L, agar 15g / L), sterilize it, pour it into a plate, inoculate it with white rot fungi, and incubate it in a constant temperature incubator at 28℃ for 72h. Wash the plate with sterile physiological saline and collect the bacterial suspension. Culture of compound nitrifying bacteria: Take 10L of nitrifying bacteria culture medium (NH4Cl 1g / L, Na2CO3 1g / L, KH2PO4 0.5g / L), sterilize it, and inoculate it with compound nitrifying bacteria (the weight ratio of nitrite bacteria to nitrifying bacteria is 1:1). Incubate at 30℃ for 48h with aeration (aeration rate 0.5L / (L·min)). Polyphosphate-accumulating bacteria culture: Take 10L of polyphosphate-accumulating bacteria culture medium (10g / L glucose, 2g / L KH2PO4, 1g / L (NH4)2SO4) and sterilize it. Inoculate with polyphosphate-accumulating bacteria and culture at 30℃ for 36 hours, alternating between aerobic culture for 12 hours (aeration rate 0.3L / (L·min)) and anaerobic culture for 8 hours. Each bacterial culture was centrifuged at 5000 r / min for 10 min, and the bacterial cells were collected. The cells were washed three times with sterile physiological saline and mixed with Pseudomonas:Bacillus:White-rot fungi:Complex nitrifying bacteria:Polyphosphate bacteria = 2:2:1:2:1 by weight. 10% sterile skim milk powder (accounting for 10% of the total weight of the mixed bacterial cells) was added as a protective agent. The mixture was dried in a vacuum freeze dryer at -50℃ and 10Pa for 14 h and then pulverized with a pulverizer to a particle size ≤100μm to obtain the composite microbial inoculum.

[0185] The preparation process of nano-hydroxyapatite is as follows: Weigh out 2.36 g of calcium nitrate (Ca(NO3)2·4H2O) and 1.32 g of diammonium hydrogen phosphate ((NH4)2HPO4) (Ca / P molar ratio 1.67), dissolve them separately in 100 mL of deionized water, and mix them to obtain a 0.1 mol / L mixed solution; The pH of the mixed solution was adjusted to 9.5 with 25wt% ammonia water, and the reaction was carried out in a constant temperature water bath at 65℃ with stirring at 180 r / min for 3.5 h. After the reaction was completed, the mixture was centrifuged at 5000 r / min for 10 min, the precipitate was collected, washed 4 times with deionized water, dried in a forced-air drying oven at 105℃ for 9 h, and then pulverized to a particle size of 50-100 nm using an ultrafine pulverizer to obtain nano-hydroxyapatite.

[0186] Example 2 This example provides an ecological restoration method for severely polluted water bodies with sediment, specifically an acidic, heavily polluted lake (acidic sediment + low-temperature environment). The specific steps are as follows: 1. Basic conditions A lake in Hunan Province was selected, with a bottom sediment thickness of 0.8 m, pH=5.3, and an ambient temperature of 10-15℃. Initial sediment parameters were: cadmium 4.2 mg / kg, mercury 1.1 mg / kg, arsenic 38 mg / kg, lead 185 mg / kg, ΣPAHs 7500 μg / kg, total nitrogen 2100 mg / kg, and total phosphorus 980 mg / kg; water transparency was 0.3 m, dissolved oxygen was 1.5 mg / L, and cyanobacteria density was high.

[0187] 2. Implementation Steps (1) Reduction of sediment pollution First, perform heavy metal remediation: Apply heavy metal remediation agent at a dosage of 300g / m³. 2 The substance was applied once every 5 days, for a total of 4 applications. Seven days after the fourth application, the heavy metal content was tested and found to be within the standard (test results: cadmium 0.58 mg / kg, mercury 0.55 mg / kg, arsenic 23 mg / kg, lead 135 mg / kg).

[0188] Further reduce organic matter and nutrients: Add slow-release sediment remediation agent at a dosage of 500g / m³. 2 The pesticide was applied once every 8 days, for a total of 3 applications. Seven days after the third application, the results were tested and found to be ΣPAHs=3800μg / kg, total nitrogen=950mg / kg, and total phosphorus=390mg / kg, meeting the standards.

[0189] (2) Improved water transparency First, add algae-controlling microorganisms (same as in Example 1), at a dosage of 120g / m³. 3 The water was released once every 3 days for a total of 3 times, and the water changed from dark green to light yellowish-green.

[0190] Then add photosynthetic bacteria and EM bacteria (volume ratio 1:3), at a dosage of 350 mL / m³. 3 One delivery completed.

[0191] Then introduce cladocerans zooplankton at a rate of 200 g / m³. 3 The treatment was completed in one go. After 20 days, the water transparency increased to 1.1m.

[0192] (3) Aquatic plant cultivation Water depth < 0.5m: Plant emergent reeds at a density of 190 plants / m². 2 .

[0193] Water depth 0.5-1.5m: Plant submerged plant Vallisneria natans at a density of 220 plants / m². 2 .

[0194] Water depth 1.5-2.5m: Plant submerged plants Elodea nuttallii + Ophiopogon japonicus (ratio 1:1), planting density 250 plants / m². 2 .

[0195] Water depth > 2.5m: Plant submerged plants Potamogeton crispus and Myriophyllum spicatum (ratio 1:1), at a density of 280 plants / m². 2 .

[0196] (4) Release of aquatic animals After the vegetation coverage reaches 82%, aquatic animals are introduced: mandarin fish, snakehead fish, bass, and silver carp (in a ratio of 1:1:2:2), totaling 550 fish per 10,000 m³. 2 (Average fish weight 200g / fish); Green shrimp + Black shrimp (ratio 1:3), total stocking volume 150kg / 10,000m³ 2 (The average length of the shrimp is 2-3cm / shrimp); Ringed snails, Radish snails, Spotted East Wind snails, and Mountain snails (in a ratio of 4:1:2:1), with a total stocking volume of 200kg / 10,000m² (the average length of the snails is 1-3cm / shrimp); Green mussels, Razor clams, Sail mussels, and Crown mussels (in a ratio of 1:1:1:1), with a total stocking volume of 120kg / 10,000m² (the average length of the mussels is 2-5cm / mussel).

[0197] 3. Repair effect Sixty days after remediation using the above method, the test results were as follows: cadmium in the sediment was 0.45 mg / kg, mercury was 0.42 mg / kg, arsenic was 19 mg / kg, and lead was 125 mg / kg (all met the standards); ΣPAHs = 980 μg / kg, total nitrogen = 720 mg / kg, and total phosphorus = 250 mg / kg; water transparency was 1.6 m, dissolved oxygen was 3.8 mg / L; the survival rate of aquatic plants was 88%; the survival rate of aquatic animals was 95%, and the ecosystem remained stable under low-temperature conditions.

[0198] The heavy metal remediation agent used in this example was prepared using the following method, with the specific steps as follows: S1. Preparation of oyster shell pretreatment agent: The same as step S1 in the preparation method of heavy metal remediation agent in Example 1.

[0199] S2. Preparation of chitosan pretreatment agent: The same as step S2 in the preparation method of heavy metal remediation agent in Example 1.

[0200] S3. Preparation of humic acid-based repair agent: The difference between step S3 and step (1) of the preparation method of heavy metal repair agent in Example 1 is that the amount of each raw material in step (1) is modified as follows: by mass parts, 15 parts humic acid, 30 parts oyster shell pretreatment agent, 30 parts chitosan pretreatment agent, 12.5 parts sodium alginate, and 12.5 parts calcium chloride powder; all other steps are the same as step S3 of the preparation method of heavy metal repair agent in Example 1.

[0201] S4. Preparation of embedded fungal remediation agent: The difference between step S4 and step (1) of the preparation method of heavy metal remediation agent in Example 1 is that the amount of each raw material in step (1) is modified as follows: by mass parts, 15 parts of oyster shell pretreatment agent, 55 parts of chitosan pretreatment agent, 15 parts of sodium alginate, and 15 parts of calcium chloride powder; and the mass ratio of fungal mud to sterile water in step (7) is modified to 1:12.5; all other steps are the same as step S4 of the preparation method of heavy metal remediation agent in Example 1.

[0202] S5. Preparation of heavy metal repair agent: The same as step S5 in the preparation method of heavy metal repair agent in Example 1.

[0203] The slow-release sediment remediation agent used in this example is composed of the following raw materials: 40 parts modified attapulgite, 25 parts compound microbial agent, 20 parts nano hydroxyapatite, 12 parts straw charcoal, 8 parts sodium alginate, 10 parts potassium humate, 6 parts calcium carbonate, 4 parts vitamin C, and 5 parts deionized water.

[0204] The compound microbial agent is made by mixing mixed microbial bodies and aseptic skim milk powder in a mass ratio of 100:10. The mixed microbial bodies are: Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria and polyphosphate-accumulating bacteria in a weight ratio of 2:2:1:2:1. The compound nitrifying bacteria are composed of nitrifying bacteria and nitrite-oxidizing bacteria in a weight ratio of 1:1.

[0205] The slow-release sediment remediation agent used in this example was prepared using the following method, with the specific steps as follows: All raw materials except deionized water are added to a twin-screw mixer, set to a speed of 400 r / min and a temperature of 30℃, and mixed for 40 minutes. At the same time, deionized water is sprayed through a spraying device. Under the shearing and extrusion action of the screws inside the machine, the material and sodium alginate are fully kneaded to form a "plastic mud-like material". The mixed material is fed into a granulator and extruded to form a particle size of 3 mm (controlled by a screen). The granules are placed in a 70℃ forced-air drying oven and dried for 3 hours to ensure that the moisture content of the granules is ≤5%. After cooling to room temperature, they are packaged to obtain a slow-release sediment remediation agent.

[0206] The preparation process of modified attapulgite is as follows: (1) Take 10 kg of natural attapulgite clay (particle size ≤ 50 μm), add 50 L of 8% hydrochloric acid solution, and activate it by stirring at 180 r / min for 3 h under constant temperature water bath at 40℃. After activation, filter it using a plate and frame filter press, collect the filter residue, and wash it repeatedly with deionized water until the pH of the filtrate is 6.8-7.2 (detected with a precision pH meter). Place the washed filter residue in a forced-air drying oven and dry it at 100℃ for 4 h. (2) Add 30L of 3% CTMAB aqueous solution (solid-liquid ratio 1kg:3L) to the dried attapulgite soil, and stir at 200r / min for 5h in a constant temperature water bath at 60℃ for modification; filter again after modification, collect the filter residue, dry at 85℃ for 4h, and pulverize with an ultra-micro pulverizer to a particle size ≤20μm (detected by a laser particle size analyzer) to obtain modified attapulgite soil.

[0207] The preparation process of compound microbial agents is as follows: The culture conditions for Pseudomonas, Bacillus, and white-rot fungi were the same as in Example 1. The difference between the culture of compound nitrifying bacteria and Example 1 was that 0.1 wt% glycerol (accounting for the total weight of the mixed bacteria) was added as a cryoprotectant during culture. The difference between the culture of polyphosphate bacteria and Example 1 was that the aerobic time was extended to 14 hours during the culture of polyphosphate bacteria.

[0208] In the compound microbial agent, the mixing ratio of microorganisms is the same as in Example 1, but the vacuum freeze-drying time is extended to 16 hours during preparation to ensure a viable count ≥10⁻⁶. 9 CFU / g.

[0209] The preparation process of nano-hydroxyapatite is as follows: Weigh out 2.36 g of calcium nitrate (Ca(NO3)2·4H2O) and 1.32 g of diammonium hydrogen phosphate ((NH4)2HPO4) (Ca / P molar ratio 1.67), dissolve them separately in 100 mL of deionized water, and mix them to obtain a 0.1 mol / L mixed solution; The pH of the mixed solution was adjusted to 10 with 25% ammonia solution. The mixture was stirred at 180 rpm for 4 h in a constant temperature water bath at 70 °C. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 10 min, the precipitate was collected, washed 4 times with deionized water, dried in a forced-air drying oven at 105 °C for 10 h, and then pulverized to a particle size of 50-100 nm using an ultrafine pulverizer to obtain nano-hydroxyapatite.

[0210] Example 3 This example provides an ecological restoration method for severely polluted water bodies with alkaline sediment (alkaline sediment + high temperature environment). The specific steps are as follows: 1. Basic conditions A reservoir was selected with a bottom sediment thickness of 0.7 m, pH = 8.3, and an ambient temperature of 28-33℃. Initial sediment parameters were: cadmium 2.5 mg / kg, mercury 0.7 mg / kg, arsenic 28 mg / kg, lead 175 mg / kg, ΣPAHs 8200 μg / kg, total nitrogen 2050 mg / kg, and total phosphorus 920 mg / kg; water transparency was 0.35 m, dissolved oxygen was 2.0 mg / L, and cyanobacteria were proliferating in large quantities.

[0211] 2. Implementation Steps (1) Reduction of sediment pollution First, perform heavy metal remediation: Apply heavy metal remediation agent at a dosage of 300g / m³. 2 The substance was applied once every 7 days, for a total of 3 applications. Seven days after the third application, the heavy metal content was tested and found to be within the standard (test results: cadmium 0.51 mg / kg, mercury 0.45 mg / kg, arsenic 21 mg / kg, lead 130 mg / kg).

[0212] Further reduce organic matter and nutrients: Add slow-release polluted sediment remediation agent at a dosage of 300g / m³. 2 The pesticide was applied once every 10 days, for a total of 3 applications. Testing was conducted the day after the third application, and the results were: ΣPAHs = 3500 μg / kg, total nitrogen = 980 mg / kg, and total phosphorus = 385 mg / kg. The results met the standards.

[0213] (2) Improved water transparency First, add algae-controlling microorganisms (same as in Example 1), at a dosage of 60 g / m³. 3 The water was treated once every 3 days, for a total of 2 times, and the water changed from dark green to yellowish-green.

[0214] Then add photosynthetic bacteria and EM bacteria (volume ratio 1:3), at a dosage of 200 mL / m³. 3 One delivery completed.

[0215] Then, cladocerans zooplankton were introduced at a concentration of 80 g / m³.3 The treatment was completed in one go. After 12 days, the water transparency increased to 1.4m.

[0216] (3) Aquatic plant cultivation Water depth < 0.5m: Plant emergent lotus plants at a density of 180 plants / m². 2 .

[0217] Water depth 0.5-1.5m: Plant submerged plant *Vallisneria natans* at a density of 180 plants / m². 2 .

[0218] Water depth 1.5-2.5m: Plant submerged plants *Hydrilla verticillata* and *Echinochloa spp.* (ratio 1:1), at a density of 200 plants / m². 2 .

[0219] Water depth > 2.5m: Plant submerged plants Potamogeton crispus and Myriophyllum spicatum (ratio 1:1), at a density of 220 plants / m². 2 .

[0220] (4) Release of aquatic animals After the vegetation coverage reaches 83%, aquatic animals are introduced: mandarin fish, snakehead fish, bass, and silver carp (in a ratio of 1:1:2:2), with a total of 700 fish per 10,000 m³. 2 (Average fish weight: 300g / fish); Green shrimp + Black shrimp (ratio: 1:3), total stocking volume: 100kg / 10,000m³ 2 (The average length of the shrimp is 2-3cm / shrimp); Ring-bellied snails, Radish snails, Spotted East Wind snails, and Mountain snails (in a ratio of 4:1:2:1), with a total stocking density of 150kg / 10,000m³. 2 (The average length of the snail is 1-3cm / snail); mussels, razor clams, sail mussels, and crown mussels (in a ratio of 1:1:1:1), with a total stocking volume of 80kg / 10,000m³. 2 (The average length of a clam is 2-5cm).

[0221] 3. Repair effect Sixty days after remediation using the above method, the following results were obtained: cadmium in the sediment was 0.32 mg / kg, mercury was 0.28 mg / kg, arsenic was 16 mg / kg, and lead was 105 mg / kg (all met the standards); ΣPAHs was 820 μg / kg, total nitrogen was 650 mg / kg, and total phosphorus was 210 mg / kg; water transparency was 1.9 m, dissolved oxygen was 4.5 mg / L; aquatic plant survival rate was 95%; aquatic animal survival rate was 99%, and the ecosystem operated stably under high temperature conditions.

[0222] The heavy metal remediation agent used in this example was prepared using the following method, with the specific steps as follows: S1. Preparation of oyster shell pretreatment agent: The same as step S1 in the preparation method of heavy metal remediation agent in Example 1.

[0223] S2. Preparation of chitosan pretreatment agent: The same as step S2 in the preparation method of heavy metal remediation agent in Example 1.

[0224] S3. Preparation of humic acid-based repair agent: The difference between step S3 and step (1) of the preparation method of heavy metal repair agent in Example 1 is that the amount of each raw material in step (1) is modified as follows: by mass, 20 parts humic acid, 25 parts oyster shell pretreatment agent, 25 parts chitosan pretreatment agent, 15 parts sodium alginate, and 15 parts calcium chloride powder; all other steps are the same as step S3 of the preparation method of heavy metal repair agent in Example 1.

[0225] S4. Preparation of embedded fungal remediation agent: The difference between step S4 and step (1) of the preparation method of heavy metal remediation agent in Example 1 is that the amount of each raw material in step (1) is modified as follows: by mass, 10 parts of oyster shell pretreatment agent, 50 parts of chitosan pretreatment agent, 20 parts of sodium alginate, and 20 parts of calcium chloride powder; and the mass ratio of fungal mud to sterile water in step (7) is modified to 1:10; all other steps are the same as step S4 of the preparation method of heavy metal remediation agent in Example 1.

[0226] S5. Preparation of heavy metal repair agent: The same as step S5 in the preparation method of heavy metal repair agent in Example 1.

[0227] The slow-release sediment remediation agent used in this example is composed of the following raw materials: 30 parts modified attapulgite, 18 parts compound microbial agent, 15 parts nano hydroxyapatite, 8 parts straw charcoal, 5 parts sodium alginate, 7 parts sodium humate, 3 parts calcium carbonate, 2 parts vitamin C, and 3 parts deionized water.

[0228] The slow-release sediment remediation agent used in this example was prepared according to the preparation method in Example 1, wherein the composition of the composite microbial agent is the same as in Example 1.

[0229] Comparative Example 1 The ecological restoration method for heavily polluted water bodies in this example differs from the restoration method in Example 1 only in that: in this example, no heavy metal remediation agent is used during the sediment pollution reduction stage; only a slow-release sediment remediation agent is used (at a dosage of 700 g / m³). 2 The slow-release sediment remediation agent was applied once every 9 days for a total of 3 times (the formula of the slow-release sediment remediation agent was the same as in Example 1). The remaining steps (transparency improvement, plant planting, and animal release) were the same as in Example 1.

[0230] Sixty days after remediation using the method described in this case, the following results were obtained: cadmium in the sediment was 1.3 mg / kg, mercury was 0.72 mg / kg, arsenic was 28 mg / kg, and lead was 155 mg / kg (all below the screening value for agricultural land soil pollution risk); ΣPAHs were 980 μg / kg, total nitrogen was 700 mg / kg, and total phosphorus was 230 mg / kg; the water transparency was 1.5 m, but the continuous release of heavy metals resulted in a survival rate of only 65% ​​for aquatic plants, with some plants showing yellowing and wilting leaves, indicating an unstable ecosystem.

[0231] Comparative Example 2 The ecological restoration method for heavily polluted water bodies in this example differs from the restoration method in Example 1 only in that: in the sediment pollution reduction stage of this example, no slow-release sediment remediation agent was used; only a heavy metal remediation agent (preparation method as in Example 1) was used, specifically at a dosage of 700 g / m³. 2 The application is carried out once every 6 days, for a total of 4 times. The remaining steps are the same as in Case 1.

[0232] Sixty days after restoration using the method described in this example, the following tests were conducted: the heavy metal content in the sediment met the standards (cadmium 0.55 mg / kg, mercury 0.49 mg / kg, arsenic 22 mg / kg, lead 130 mg / kg); however, ΣPAHs=4200 μg / kg, total nitrogen=1350 mg / kg, and total phosphorus=680 mg / kg (all below the standards); the water transparency was 1.2 m, excessive nutrients led to a secondary outbreak of blue-green algae, the growth of aquatic plants was inhibited, the coverage rate was only 60%, and the ecological restoration failed.

[0233] Comparative Example 3 The ecological restoration method for the heavily polluted water body in this example differs from the restoration method in Example 1 only in that the order of release during the water transparency improvement stage is adjusted as follows: first, release cladoceran zooplankton (total release amount 140g / m³). 3 Then, add algae-controlling microorganisms (i.e., Staphylococcus: Flavobacterium tumefaciens mass ratio = 1:1, dosage 90g / m³). 3 (Repeat once every 3 days, for a total of 2 times), and finally add photosynthetic bacteria and EM bacteria (volume ratio 1:3, dosage 280mL / m³). 3 The remaining steps are the same as in Example 1.

[0234] Sixty days after remediation using the method described in this example, the following results were obtained: Cadmium in the sediment was 0.52 mg / kg, Mercury 0.48 mg / kg, Arsenic 22 mg / kg, and Lead 132 mg / kg, all meeting heavy metal standards; ΣPAHs = 970 μg / kg, Total Nitrogen = 1050 mg / kg, and Total Phosphorus = 420 mg / kg (Total Nitrogen and Total Phosphorus did not meet standards); Water transparency was 0.8 m, dissolved oxygen was 2.6 mg / L, and cyanobacteria density was 7.3 × 10⁻⁶.6 Cells / L; a large number of zooplankton died within 3 days of release (mortality rate reached 85%); the survival rate of aquatic plants was only 50% due to insufficient light, with Vallisneria natans survival rate of 45% and Hydrilla verticillata survival rate of 48%, and the plant leaves became thinner and lighter in color, indicating that the ecosystem construction failed.

[0235] Comparative Example 4 The only difference between the ecological restoration method for heavily polluted water bodies with sediment in this example and the restoration method in Example 1 is: In this example, the order of addition was adjusted only during the water transparency improvement stage: photosynthetic bacteria and EM bacteria (volume ratio 1:3, addition amount 280mL / m³) were added first. 3 Then, add algae-controlling microorganisms (Staphylococcus: Flavobacterium tumefaciens mass ratio = 1:1; dosage 90g / m³). 3 (1 time every 3 days, for a total of 2 times), and finally release cladocerans zooplankton (release amount 140g / m³). 3 The remaining steps (sediment pollution reduction, plant planting, animal release) are the same as in Example 1.

[0236] Sixty days after remediation using the method described in this example, the following results were obtained: Cadmium in the sediment was 0.53 mg / kg, Mercury 0.47 mg / kg, Arsenic 21 mg / kg, and Lead 131 mg / kg (heavy metals met standards); ΣPAHs = 950 μg / kg, Total Nitrogen = 1120 mg / kg, and Total Phosphorus = 480 mg / kg (Total Nitrogen and Total Phosphorus did not meet standards); Water transparency was 0.6 m, dissolved oxygen was 2.5 mg / L, and cyanobacteria density was 8.5 × 10⁻⁶. 6 Cells / L; zooplankton mortality rate reached 90%, aquatic plant survival rate was only 45%, some emergent plant roots rotted, submerged plant leaves fell off, and ecosystem construction failed.

[0237] Comparative Example 5 The only difference between the ecological restoration method for heavily polluted water bodies in this example and the restoration method in Example 1 is: In this example, the only difference is that the algae-controlling microorganisms (Staphylococcus: Flavobacterium tumefaciens mass ratio = 1:1; dosage 90g / m³) were not added sequentially during the water transparency improvement stage. 3 (1 time every 3 days, for a total of 2 times), photosynthetic bacteria and EM bacteria (volume ratio 1:3, dosage 280mL / m³). 3 ), cladocerans (release amount 140g / m³) 3 The ingredients are mixed and added at the same time, and the remaining steps are the same as in Example 1.

[0238] Sixty days after remediation using the method described in this example, the following results were obtained: Cadmium 0.54 mg / kg, Mercury 0.48 mg / kg, Arsenic 22 mg / kg, Lead 133 mg / kg in the sediment; ΣPAHs = 960 μg / kg, Total Nitrogen = 1250 mg / kg, Total Phosphorus = 580 mg / kg; Water transparency 0.7 m, Dissolved Oxygen 2.8 mg / L, Cyanobacteria density = 6.2 × 10⁻⁶. 6 Cells / L; zooplankton survival rate was only 30%, aquatic plant coverage was only 55%, with Vallisneria natans survival rate of 48% and Hydrilla verticillata survival rate of 52%; a small number of fish died due to water quality deterioration (mortality rate 15%), and the ecosystem stability was extremely poor.

[0239] Comparative Example 6 The only difference between the ecological restoration method for heavily polluted water bodies in this example and the restoration method in Example 2 is: In this example, only the aquatic plant planting stage was not coordinated with water depth and air temperature: all water depths (0.5-2.5m) were planted with *Hydrilla verticillata* (planting density 200 plants / m²). 2 (This example does not include cold-resistant varieties such as Elodea nuttallii and Ophiopogon japonicus; the remaining steps are the same as in Example 2.)

[0240] Sixty days after remediation using the method described in this example, the following results were obtained: sediment pollutant levels met standards (cadmium 0.58 mg / kg, mercury 0.55 mg / kg, arsenic 23 mg / kg, lead 135 mg / kg; ΣPAHs = 980 μg / kg, total nitrogen = 720 mg / kg, total phosphorus = 250 mg / kg); water transparency was 1.4 m, dissolved oxygen was 3.5 mg / L, and cyanobacteria density was 1.5 × 10⁻⁶. 4 Cells / L; however, *Hydrilla verticillata* grows slowly in low-temperature environments, with a survival rate of only 55%, and the overall coverage of aquatic plants is 70%, with many areas lacking vegetation; the survival rate of aquatic animals is only 70%, with the survival rate of freshwater shrimp at 65%, *Bellamya aeruginosa* at 68%, and mandarin fish at 75%, indicating an incomplete ecosystem structure and poor stability.

[0241] Comparative Example 7 The only difference between the ecological restoration method for heavily polluted water bodies in this example and the restoration method in Example 1 is: In this example, only during the water transparency improvement stage, algae-controlling microorganisms, photosynthetic bacteria, EM bacteria, and zooplankton are not added. Instead, a traditional flocculant (polyaluminum chloride) is added at a dosage of 500 mg / L, once every 7 days, for a total of 3 times. The remaining steps are the same as in Example 1.

[0242] Sixty days after remediation using the method described in this example, the following results were obtained: Cadmium 0.85 mg / kg, Mercury 0.63 mg / kg, Arsenic 25 mg / kg, Lead 148 mg / kg in the sediment (heavy metals were released again, failing to meet standards); ΣPAHs = 990 μg / kg, Total Nitrogen = 710 mg / kg, Total Phosphorus = 240 mg / kg (organic matter and nutrients met standards); Water transparency 1.4 m, Dissolved oxygen 3.6 mg / L, pH = 8.9 (disruption of acid-base balance), Blue-green algae density = 1.8 × 10⁻⁶. 4 Cells / L; the survival rate of aquatic plants was only 60%, with 62% survival rate of sweet flag, 58% survival rate of Vallisneria natans, and 59% survival rate of Hydrilla verticillata; fish showed stress response (abnormal swimming and reduced feeding), with a survival rate of 75%, posing a risk of secondary pollution and severely damaging the ecosystem.

[0243] In summary, this invention utilizes a combined heavy metal remediation agent and a slow-release sediment remediation agent. The synergistic effect of these two agents reduces the content of heavy metals, organic matter, and other pollutants in heavily polluted water bodies, thus achieving in-situ treatment without the need for dredging or off-site disposal of sludge. Furthermore, after reducing the pollutants in the sediment, aquatic plants can be directly planted in the sediment for ecological restoration of the water body without generating secondary pollution. The sequential and synergistic effects of algae-controlling microorganisms, photosynthetic bacteria, EM bacteria, and zooplankton effectively improve water transparency. Moreover, it eliminates the need for domesticated zooplankton to consume blue-green algae and improve water transparency. In addition, this invention optimizes the planting method by combining aquatic plants according to water depth and climate, achieving a synergistic remediation effect and ensuring a stable and lasting remediation effect.

[0244] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An ecological restoration method for heavily polluted water bodies with sediment, characterized in that: Includes the following steps: S1: Add heavy metal remediation agents to the water body; S2: Add slow-release sediment remediation agent to the water body; S3: First, release algae-controlling microorganisms into the water, then release a mixture of photosynthetic bacteria and EM bacteria, and finally release zooplankton; S4: Plant aquatic plants according to water depth; plant emergent plants in areas with water depth < 0.5m, and plant submerged plants in areas with water depth ≥ 1.5m. S5: When the coverage of aquatic plants in the water body is ≥80%, aquatic animals shall be released into the water body.

2. The ecological restoration method for heavily polluted water bodies with sediment according to claim 1, characterized in that: Step S3 has at least one of the following characteristics: (a1) The algae-controlling microorganisms are Staphylococcus and Flavobacterium tumefaciens in a mass ratio of 1:(0.8~1.2); (a2) The dosage of the algae-controlling microorganisms is 50-140 g / m³. 3 ; (a3) The algae-controlling microorganisms are introduced every 2-4 days; (a4) The volume ratio of photosynthetic bacteria to EM bacteria is 1:(2-4); (a5) The total amount of photosynthetic bacteria and EM bacteria added is 150-400 mL / m 3 ; (a6) The zooplankton include cladocerans; (a7) The amount of zooplankton released is 60-300 g / m³. 3 .

3. The ecological restoration method for heavily polluted water bodies with sediment as described in claim 1, characterized in that: Step S4 is as follows: Plant aquatic plants according to the water depth, and plant emergent plants in areas where the water depth is <0.5m; Submerged plants (A) should be planted in areas with a water depth of 0.5-1.5m. Submerged plants (B) should be planted in areas with a water depth of 1.5-2.5m. Plant submerged plants (C) in areas with a water depth greater than 2.5m; The submerged plant A is selected from at least one of Vallisneria natans and Elaeagnus pungens. The submerged plant B is selected from at least one of the following: Hydrilla verticillata, Elodea nuttallii, Potamogeton crispus, Ceratophyllum demersum, Potamogeton malaianus, Dianthus simonii, and Dianthus macrocarpa. The submerged plant C is selected from at least one of Potamogeton crispus and Myriophyllum spicatum. The emergent plants are selected from at least one of calamus, reed, and lotus.

4. The ecological restoration method for heavily polluted water bodies with sediment as described in claim 1, characterized in that: The heavy metal remediation agent includes humic acid-based remediation agents and encapsulated microbial remediation agents; the raw materials for preparing the humic acid-based remediation agent include humic acid, oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate, and calcium chloride; the encapsulated microbial remediation agent includes a core material and a calcium alginate coating layer; the calcium alginate coating layer coats at least a portion of the surface of the core material; the core material includes a porous carrier and microorganisms; the microorganisms are loaded in the porous carrier; the raw materials for preparing the porous carrier include oyster shell pretreatment agent, chitosan pretreatment agent, sodium alginate, and calcium chloride; The oyster shell pretreatment agent includes active calcium and zinc oxide; the active calcium is formed by calcining and hydrating oyster shells sequentially; the chitosan pretreatment agent is formed by activating chitosan with inorganic peroxide.

5. The ecological restoration method for heavily polluted water bodies with sediment according to claim 4, characterized in that: The humic acid-based remedial agent has at least one of the following characteristics: (b1) The humic acid-based remediation agent is a porous material; (b2) The humic acid-based repair agent comprises the following raw materials in parts by weight: 8-22 parts humic acid, 23-37 parts oyster shell pretreatment agent, 23-37 parts chitosan pretreatment agent, 8-17 parts sodium alginate, and 8-17 parts calcium chloride. (b3) The humic acid-based repair agent is prepared by mixing and granulating the raw materials for preparing the humic acid-based repair agent, and then calcining them at 180-220℃.

6. The ecological restoration method for heavily polluted water bodies with sediment according to claim 4, characterized in that: The embedded bacterial remediation agent has at least one of the following characteristics: (c1) The porous carrier comprises the following raw materials in parts by weight: 8-22 parts oyster shell pretreatment agent, 48-62 parts chitosan pretreatment agent, 8-22 parts sodium alginate, and 8-22 parts calcium chloride; (c2) The porous carrier is prepared by mixing the raw materials for the preparation of the porous carrier, granulating them, and then calcining them at 180-220℃; (c3) The microorganisms include at least one of Bacillus megaterium, Bacillus licheniformis, Pseudomonas stearothermiae, or white-rot fungi; (c4) The mass ratio of the porous carrier to the microbial bacteria is 1:(0.1~0.5); (c5) The mass ratio of the core material to the calcium alginate coating is 1:(0.01~0.1); (c6) The mass ratio of the active calcium to the zinc oxide is 1:(4~7)×10 -7 .

7. The ecological restoration method for heavily polluted water bodies with sediment according to claim 4, characterized in that: The mass ratio of the humic acid-based remedial agent to the embedded bacterial remedial agent is 1:(0.8~3.5).

8. The ecological restoration method for heavily polluted water bodies with sediment according to claim 1, characterized in that: The slow-release sediment remediation agent comprises the following components in parts by weight: 30-40 parts modified attapulgite, 18-25 parts composite microbial agent, 15-20 parts nano hydroxyapatite, 8-12 parts straw charcoal, 5-8 parts binder, 7-10 parts humic acid material, 3-6 parts calcium carbonate, 2-4 parts antioxidant, and 3-6 parts water. The modified attapulgite is obtained by modifying attapulgite with acid and surfactant.

9. The ecological restoration method for heavily polluted water bodies with sediment according to claim 8, characterized in that: The compound microbial agent includes Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria; Alternatively, the compound microbial agent comprises Pseudomonas, Bacillus, white-rot fungi, compound nitrifying bacteria, and polyphosphate-accumulating bacteria in a weight ratio of (1.5-2.5):(1.5-2.5):(0.8-1.2):(1.5-2.5):

1.

10. The ecological restoration method for heavily polluted water bodies with sediment according to claim 1, characterized in that: The dosage of the heavy metal remediation agent is 100-2000 g / m³. 2 And / or, the dosage of the slow-release sediment remediation agent is 100-2000 g / m³. 2 .