A bixbyite-oxygen releasing agent composite type sediment remediation material and a preparation and application method thereof

Abstract

The application belongs to the field of environmental governance, and provides a water sodium manganese ore-oxygen releasing agent composite type sediment repair material and a preparation and application method thereof, which comprises modified oxygen releasing agent, water sodium manganese ore, microbial flora and embedding matrix, the embedding matrix comprises calcium alginate, polyvinyl alcohol and water cross-linked formed hydrogel, wherein the microbial flora comprises domesticated aerobic denitrification and phosphorus removal mixed flora.The water sodium manganese ore-oxygen releasing agent composite type sediment repair material utilizes the photoelectric catalytic activity of water sodium manganese ore and the oxygen releasing ability of oxygen releasing compound, improves the oxidation-reduction potential of sediment, enhances the sustained degradation ability of organic pollutants, cooperatively removes nitrogen pollutants in water environment, enhances the in-situ repair effect of sediment, is applied to sediment repair, and is more efficient, environment-friendly and has long-term effect.

Description

Technical Field

[0001] This invention belongs to the field of environmental remediation, specifically relating to a sediment remediation agent composed of sodium manganese ore and oxygen-releasing agent, its preparation method and application, and particularly to a technology for removing pollutants through the synergistic effect of photoelectric effect and oxygen release. Background Technology

[0002] The main methods for treating river and lake sediment pollution include ex-situ treatment and in-situ remediation. In-situ remediation avoids large-scale sediment migration and subsequent treatment, minimizing disruption to the ecosystem. Based on technical principles, existing in-situ sediment remediation technologies mainly include physical remediation, chemical remediation, and bioremediation. Physical remediation methods, such as dredging and silt removal, require subsequent ex-situ remediation, potentially leading to secondary pollution and disrupting the habitat of benthic organisms and microorganisms. Chemical remediation methods, such as chemical passivation and oxidation, are costly, complex, and carry the risk of secondary release. Remediation methods involving the addition of biological agents are time-consuming and inefficient.

[0003] Oxygenation is a common method in river and lake sediment remediation. Its main principle is to increase the dissolved oxygen concentration in the water covering the sediment, promoting the biochemical degradation and decomposition of various pollutants by aerobic microorganisms, thereby improving water quality. Oxygenation methods mainly include mechanical aeration and the addition of oxygen-releasing agents. Oxygen-releasing agents are easier to add and have lower construction and operating costs, making them more convenient for river water body restoration. Oxygen-releasing agents (ORCs) used for water body remediation are mostly peroxides, including calcium peroxide (CaO2), magnesium peroxide (MgO2), hydrogen peroxide (H2O2), and sodium percarbonate (Na2CO3·H2O2). These react with water to release oxygen, increasing the dissolved oxygen level. Among these, calcium peroxide has a relatively low oxygen release rate and a long continuous release time, and it also has a high oxygen content and low cost, making it the most commonly used oxygen-releasing agent material. Adding oxygen-releasing agents has the following positive effects: increased dissolved oxygen concentration, improved oxidation-reduction potential (ORP), promoted aerobic microbial growth, inhibited phosphorus release from sediment, enhanced sediment adsorption capacity, and minimal environmental side effects. However, calcium peroxide, as a single oxidizing matrix, primarily releases oxygen through chemical processes, limiting its potential to promote organic matter degradation. Furthermore, its strong oxidizing properties promote the decomposition of sediment organic matter and the conversion of ammonia nitrogen to nitrate nitrogen, showing good effects primarily on ammonia nitrogen removal, but its removal effect on nitrate nitrogen is very limited, thus increasing the release of total nitrogen.

[0004] On the other hand, this type of ORC exhibits reduced chemical stability under acidic conditions, resulting in poor oxygen release and remediation effects. Furthermore, the oxygen release process of this type of ORC generates large amounts of calcium hydroxide, leading to an increase in the pH of the overlying water, which is detrimental to the survival and growth of submerged plants. Therefore, it is necessary to enhance the environmental adaptability and durability of sediment remediation agents.

[0005] Sodium manganese ore is widely distributed in nature and can be easily prepared through simple chemical synthesis methods, showing potential for large-scale applications. It is a layered manganese oxide, a two-dimensional metal oxide composed of octahedral MnO6 basic units. Its interlayers are rich in water and cations (H+). + K + Na + Ca 2+ Ba 2+ Mn, containing three valence states (+2, +3, +4), has controllable interlayer spacing and abundant electrochemical active sites, making it widely used in secondary batteries, supercapacitors, water treatment, and catalysis.

[0006] In the field of aquatic environment, the porous structure and large specific surface area of ​​manganese hydrate make it an excellent adsorbent for pollutants. Patent No. CN201910626892.9 provides a modified manganese hydrate, its preparation method, and its applications, utilizing the modified manganese hydrate to enhance its adsorption capacity for heavy metal ions. Manganese hydrate can act as both an electron sink, being "charged" by reducing agents such as organic carbon to reduce manganese oxidation, and an electron source, "discharging" in the presence of oxidants (such as oxygen and nitrate nitrogen), exhibiting active "battery" characteristics. Its "charging" rate by organic carbon reduction is approximately 0.4–0.8 μM / day, and its oxidation rate by oxygen is approximately 0.3–0.6 μM / day. Furthermore, manganese hydrate can remove ammonia nitrogen through chemical oxidation or microbial action (Mnammox), and can oxidize Mn through microbial coupling with nitrate reduction. 2+ The regeneration of manganese oxides was achieved through the resynthesis of bio-based manganese oxides. This demonstrates that sodium manganese ore can drive the oxidation of large amounts of organic carbon and the transformation and removal of nitrogen pollutants through multiple reversible redox cycles and flexible structural adjustment strategies.

[0007] More importantly, the "mineral film" of naphthoic ore exhibits a semiconductor effect in the photoelectric conversion of sunlight, namely the photoelectric effect. Alkaline naphthoic ore has a band gap of 1.77 eV, absorbing light in the wavelength range of 300-700 nm, and can utilize visible light to generate photogenerated electrons and holes. It has been reported that naphthoic ore, as a photocatalyst, has strong adaptability to electron donors and high utilization efficiency; when humic acid is used as an electron donor, the manganese reduction is 1.78-4.46 times that of methanol. This ability allows naphthoic ore to more effectively catalyze the oxidation of organic pollutants, which is of great significance for the removal of organic pollutants from sediment.

[0008] In view of the limitations of existing sediment remediation materials, and given the unique advantages of sodium manganese ore, this invention aims to enhance the removal efficiency of pollutants from river and lake sediments and overlying water by utilizing the combined effect of sodium manganese ore and oxygen-releasing agents and the synergistic effect of photoelectrocatalysis to remediate sediments. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material and its preparation and application methods. It utilizes the photoelectric effect of water-sodium manganese ore to synergistically enhance the oxygen-releasing capacity of oxygen-releasing compounds, thereby improving sediment remediation. It is highly efficient, environmentally friendly, and has long-term effects.

[0010] The purpose of this invention is to provide a composite sediment remediation material of sodium manganese ore-oxygen release agent, which includes a modified oxygen release agent, sodium manganese ore, microbial community and embedding matrix. The embedding matrix includes a hydrogel formed by cross-linking calcium alginate, polyvinyl alcohol and water. The microbial community includes a domesticated aerobic denitrification and phosphorus removal mixed community.

[0011] This invention combines the photoelectric effect of sodium manganese ore with the oxygen-releasing capacity of an oxygen-releasing agent. The photoelectric effect of sodium manganese ore generates photogenerated electrons and holes. Photogenerated electrons drive denitrification, while photogenerated holes oxidize ammonia nitrogen and organic matter, promoting the transformation and degradation of pollutants. The oxygen-releasing agent generates dissolved oxygen in situ in surface sediments, further increasing the dissolved oxygen concentration in the sediment. This is beneficial for the growth and metabolism of aerobic bacteria, promoting the biodegradation and nitrification of organic matter. Oxygen can participate in the electron cycle of the photoelectric effect of sodium manganese ore, affecting the valence state of Mn in the ore and thus influencing the Jahn-Teller effect, maintaining the electronic structure of the material, improving the photocatalytic activity of sodium manganese ore, and enhancing its continuous degradation capacity for organic pollutants. It can synergistically remove pollutants from sediment and the aquatic environment under both light and dark conditions, improve the redox potential of sediment, and promote in-situ sediment remediation. Furthermore, through the reduction reaction of sodium manganese ore and photocatalytic hydrogen ion production, the alkaline substances generated by the oxygen-releasing agent are neutralized, maintaining the pH stability of the water body.

[0012] In this invention, the combined mass of the modified oxygen-releasing agent and sodium manganese ore accounts for 50-80% of the total mass of the composite sediment remediation material, and the mass ratio of the modified oxygen-releasing agent to sodium manganese ore is 2-5:1.

[0013] Furthermore, the modified oxygen-releasing agent is a modified oxygen-releasing compound with a silica layer supported on the surface of a peroxide. The peroxide includes at least one of CaO2, MgO2, Na2CO4, and Na2O2. Calcium peroxide is preferred, as it has a low oxygen release rate and a long sustained release time, high oxygen content, and low cost.

[0014] Hydrogen peroxide, generated by the reaction of peroxide with water, passes through the silica layer and reacts with sodium manganese ore under the catalysis of water to produce oxygen. This can effectively alleviate the problem of excessively rapid oxygen production rate of calcium peroxide in aqueous solution, and at the same time prolong the reaction time of hydroxyl radicals, superoxide radicals and other free radicals generated during oxygen release with organic pollutants.

[0015] The preparation method of the above-mentioned modified oxygen-releasing compound includes the following steps:

[0016] (1) Disperse the peroxide powder in a solution composed of anhydrous ethanol, deionized water and concentrated ammonia, and ultrasonically disperse for 15-50 min to obtain a suspension;

[0017] (2) Tetraethyl orthosilicate (TEOS) was added dropwise to the above suspension and stirred continuously for 6-8 hours under a water bath at 40-60℃. After washing and drying, the product was obtained as a modified oxygen-releasing compound.

[0018] The concentration of concentrated ammonia is 25-28 wt%, and the volume ratio of anhydrous ethanol, deionized water, and concentrated ammonia is 20-40:5-20:0.1-5. The ratio of tetraethyl orthosilicate to peroxide is 2-10 ml:1 g.

[0019] Preferably, the above-mentioned method for preparing sodium manganese ore includes the following steps:

[0020] (1) Manganese hydroxide Mn(OH)2 solution was prepared by mixing 0.02-0.2M manganese salt solution and 0.5-2.0M alkaline solution;

[0021] (2) Add 0.05-0.5M potassium permanganate solution to manganese hydroxide (Mn(OH)2) solution, react for 12-24 hours, filter the resulting precipitate from the solution, wash and dry it, and grind it to obtain sodium manganese ore. Sodium manganese ore with photoelectric effect capability is prepared by the above chemical synthesis method.

[0022] The manganese salt solution includes at least one of manganese nitrate, manganese chloride, or manganese sulfate solution, and the alkaline solution includes at least one of NaOH or KOH.

[0023] Preferably, the aerobic denitrification and phosphorus removal mixed microbial community is an aerobic denitrification and phosphorus removal mixed microbial community inoculated from activated sludge, a microbial community adapted to aerobic conditions through acclimatization and cultivation with sodium manganese ore and light source irradiation, and a microbial community with the photoelectric effect of sodium manganese ore.

[0024] The specific method involves adding sodium manganese ore to activated sludge containing nitrates, phosphates, and organic pollutants that has undergone aeration pretreatment, inoculating it with a mixed aerobic denitrification and phosphorus removal bacteria, and acclimating and cultivating microbial communities adapted to aerobic conditions and the photoelectric effect of sodium manganese ore under the irradiation of sodium manganese ore and light source.

[0025] Preferably, the aerobic denitrification and phosphorus removal mixed microbial community is a mixed microbial community of aerobic denitrifying bacteria and polyphosphate-accumulating bacteria.

[0026] The present invention also aims to provide a method for preparing the above-mentioned water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material, comprising the following steps:

[0027] (1) Mix polyvinyl alcohol, sodium alginate and water evenly, and heat at 80-110℃ for 1-2 hours or more to form a hydrogel;

[0028] (2) Add the modified oxygen-releasing agent and sodium manganese ore to the above hydrogel, and add the microbial suspension at the same time. After stirring evenly, pour into a mold and freeze to form.

[0029] (3) The frozen material obtained in step (2) is immersed in a saturated H3BO3 solution containing CaCl2 for 24-72 hours, washed and air-dried to obtain a water-sodium manganese ore-oxygen release agent composite sediment remediation material.

[0030] The ratio of polyvinyl alcohol, sodium alginate, and water is 3-8g:1g:50-200mL. The ratio of sodium manganese ore and microbial suspension is 1g:15-25ml, and the concentration of the microbial suspension is 10. 7 -10 9 CFU / mL. The microbial suspension accounts for 15%-25% of the total mass of the hydrogel.

[0031] Polyvinyl alcohol, as a dispersant and encapsulating agent, improves the dispersibility of sodium manganese ore and calcium peroxide on the one hand, and encapsulates the microbial community after domestication and cultivation on the other.

[0032] This invention provides a method for applying the above-mentioned sodium manganese ore-oxygen-releasing agent composite sediment remediation material, including the steps of laying the sodium manganese ore-oxygen-releasing agent composite sediment remediation material on the mud-water interface to be remediated, and irradiating it with sunlight, solar energy, optical fiber transmission light source, LED light source, etc., to activate the photoelectric effect of sodium manganese ore through light irradiation, and synergistically with the oxygen-releasing function of the oxygen-releasing agent and the metabolic action of microorganisms to remediate nitrogen, phosphorus and organic pollutants in the sediment.

[0033] The photoelectric effect of sodium manganese ore, the synergistic effect of oxygen-releasing agents and microorganisms remove pollutants and repair surface sediment.

[0034] Furthermore, the light intensity I at the mud-water interface to be repaired reached 200W / m. 2 above.

[0035] The light intensity at the mud-water interface is calculated using the following formula: I = I0·e -k·d Where I is the light intensity reaching the mud-water interface, I0 is the light intensity of the light source at the water surface or underwater, k is the light attenuation coefficient, and d is the propagation distance of light in the water.

[0036] The value of the optical attenuation coefficient k:

[0037] In clear freshwater lakes and rivers, k = 0.1-0.3m -1 ;

[0038] Moderately turbid water (suspended particle concentration 50-200 mg / L, turbidity 20-100 NTU), k = 0.3-1.0 m -1 ;

[0039] Turbid water (suspended particle concentration > 200 mg / L, turbidity > 100 NTU), k > 1.0 m -1 .

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] (1) Synergistic effect enhances degradation efficiency. This invention combines the photoelectric effect of sodium manganese ore with the oxygen-releasing capacity of oxygen-releasing agents. The photoelectric effect of sodium manganese ore drives denitrification with photogenerated electrons and oxidizes ammonia nitrogen and organic matter with photogenerated holes, promoting the transformation and degradation of pollutants. The oxygen-releasing agent generates dissolved oxygen in situ in the surface sediments. The oxygen can participate in the electron cycle of the photoelectric effect of sodium manganese ore, affecting the valence state change of Mn in sodium manganese ore, thereby affecting the Jahn-Teller effect, maintaining the electronic structure of the material, improving the photocatalytic activity of sodium manganese ore, and enhancing its ability to continuously degrade organic pollutants.

[0042] (2) Simultaneous nitrogen and phosphorus removal. This invention combines the photoelectric effect of sodium manganese ore with the oxygen-releasing capacity of calcium peroxide. The oxygen-releasing material generates dissolved oxygen in situ in the surface sediment, promoting the enrichment of aerobic denitrifying bacteria and polyphosphate-accumulating bacteria. At the same time, calcium ions fix phosphorus through physicochemical action, thus achieving simultaneous nitrogen and phosphorus removal and improving treatment efficiency. The photoelectric effect of sodium manganese ore generates photogenerated electrons and holes. The photogenerated electrons drive denitrification, and the photogenerated holes oxidize ammonia nitrogen and organic matter, promoting the transformation and degradation of pollutants.

[0043] (3) Enhanced environmental friendliness. Traditional chemical flocculation and sedimentation methods for removing phosphates require the addition of large amounts of chemicals, which may cause secondary pollution to the environment. The water-sodium-manganese ore-oxygen-releasing agent composite sediment remediation material of this invention is environmentally friendly, reduces the use of chemicals, and reduces the negative impact on the environment.

[0044] (4) Strong system stability. By pre-culturing and embedding functional bacteria, the microbial adaptability of the remediation agent is improved, and the start-up time is shortened. At the same time, aerobic denitrifying bacteria are more likely to become the dominant bacteria in an oxygen-rich environment. They grow and reproduce quickly and are more adaptable to low temperature, high salt and other environments. Moreover, the aerobic denitrification process is more stable than the biological denitrification process under anaerobic or hypoxic conditions and is easier to operate.

[0045] (5) pH stability. Sodium manganese ore can neutralize the alkalinity released by peroxides through both biochemical oxidation and photocatalysis: hydrogen ions are generated when high-valence manganese in sodium manganese ore is reduced; photogenerated holes generated during photocatalysis in sodium manganese ore react with water to produce hydrogen ions (MnO2 + hν → e). - +h + h + +H₂O→H + +OH). Therefore, this composite remediation material can neutralize the alkaline substances released by peroxides in multiple ways, thereby regulating the pH value of the water body and reducing the negative impact on the aquatic ecosystem.

[0046] (6) The preparation process of the bottom sediment remediation material of the present invention is simple, and it can achieve long-term stable remediation of bottom sediment, avoiding the problem of frequent repeated treatment, and is easy to produce and apply on a large scale.

[0047] (7) This invention can be applied to in-situ remediation of bottom sediment and water quality maintenance measures of overlying water, reducing the total amount of bottom sediment that needs to be dredged, reducing the disturbance to the surrounding environment, reducing the treatment and disposal costs of dredged bottom sediment, and also facilitating ecological reconstruction after dredging.

[0048] When applied to in-situ restoration of rivers and lakes, this invention offers the following beneficial effects:

[0049] (1) Improve the sediment environment. Increase the dissolved oxygen level in the sediment to create an aerobic environment. This helps promote the activity of microorganisms in the sediment and enhances their ability to degrade nitrogen, phosphorus and organic matter, thereby improving the overall ecological environment of the sediment. In addition, by improving the redox potential of the sediment, the above materials can promote the growth of plants and benthic animals in the sediment, providing a good foundation for ecological restoration.

[0050] (2) Improve water quality. Sediment remediation can effectively reduce the release of harmful substances from the sediment, thereby protecting the quality of the overlying water and reducing secondary pollution. By improving the dissolved oxygen environment on the surface of the sediment, it also helps to improve the transparency and redox potential of the water body, thus achieving faster water quality improvement.

[0051] (3) High efficiency and stability. The synergistic effect of multiple elements promotes simultaneous nitrogen and phosphorus removal and in-situ remediation of sediment. It can continuously release oxygen for a relatively long period of time, providing a continuous driving force for aerobic denitrification and phosphate removal, thereby achieving long-term water quality improvement.

[0052] (4) High adaptability. It can synergistically remove pollutants in mud and water environments under both light and dark conditions, and is suitable for various water quality conditions, including urban sewage and industrial wastewater. It has good adaptability and broad application prospects.

[0053] (5) Reduce greenhouse gas emissions. Under the long-term influence of oxygen-releasing agents, aerobic denitrifying bacteria are enriched, nitrogen removal efficiency is improved, and nitrates are completely converted into N2, which helps reduce greenhouse gas emissions.

[0054] In summary, the water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material of this invention, by utilizing the synergistic effect of water-sodium manganese ore and oxygen-releasing agent, can be applied to sediment remediation and treatment of overlying water pollutants, and has significant advantages in improving remediation efficiency, reducing costs, reducing environmental pollution, and enhancing system stability. Attached Figure Description

[0055] Figure 1 The band gap width for sodium manganese ore;

[0056] Figure 2 The photocurrent response curve of sodium manganite;

[0057] Figure 3 To investigate the effects of adding different remediation agents on the ammonia nitrogen concentration in the overlying water;

[0058] Figure 4 To investigate the effects of adding different remediation agents on the nitrate and nitrogen concentration in the overlying water;

[0059] Figure 5 The total organic carbon content in the sediment of each treatment group after 10 days of reaction;

[0060] Figure 6 Diagram illustrating the mechanism of action of a composite sediment remediation material consisting of sodium manganese ore and oxygen-releasing agent. Detailed Implementation

[0061] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0062] This invention describes in detail the selection and modification of oxygen-releasing agents, the preparation of sodium manganese ore, the cultivation of functional microorganisms, the preparation of composite sediment remediation materials, and their application methods, providing specific technical solutions for the efficient purification of river and lake sediments. Through the implementation of this invention, the remediation efficiency of river and lake sediments can be effectively improved, costs reduced, and secondary pollution decreased, achieving long-term stable restoration of river and lake aquatic ecosystems.

[0063] The technical principles involved in this invention are as follows: Sodium manganese ore exhibits a photoelectric effect, generating photoelectron-hole pairs through irradiation with sunlight or visible light. Photogenerated holes can oxidize water to produce hydroxyl radicals and superoxide radicals, promoting the oxidative degradation of organic pollutants. Photogenerated electrons are transferred to nitrates via the electron transport chain, promoting denitrification. Simultaneously, calcium peroxide reacts with water to generate hydrogen peroxide, which further decomposes to produce oxygen, increasing the dissolved oxygen concentration in the sediment. This is beneficial for the growth and metabolism of aerobic bacteria, promoting the biodegradation and nitrification of organic matter. Oxygen can act as an electron acceptor, participating in the electron cycle of the photoelectric effect in sodium manganese ore. This affects the valence state of Mn in sodium manganese ore, thereby influencing the Jahn-Teller effect, maintaining the electronic structure of the material, improving the photocatalytic activity of sodium manganese ore, and enhancing its ability to degrade organic pollutants.

[0064] This is a composite sediment remediation material consisting of sodium manganese ore and an oxygen-releasing agent. It comprises oxygen-releasing compounds, sodium manganese ore, and embedded functional microorganisms. The mass ratio of these three components is 2-5:1:0.15-0.25.

[0065] Under light-free conditions, sodium manganese ore undergoes chemical oxidation or microbial oxidation of ammonia nitrogen and organic matter, while manganese is reduced to divalent manganese. Subsequently, bio-manganese oxide is formed on the surface of the sodium manganese ore through microbial induction, ensuring the continuation of the biochemical reactions. Calcium peroxide reacts with water to generate hydrogen peroxide, which further decomposes to release oxygen. By improving dissolved oxygen in the water, this stimulates the activity of functional microorganisms to remove pollutants from the sediment. Under light-provided conditions, this material can release oxygen more effectively under the mediation of the photoelectric effect of sodium manganese ore. The released oxygen, in turn, participates in the discharge process of the sodium manganese ore's "soil battery" effect, forming a photoelectric effect-oxygen release process interaction regulation. Light energy is used to activate microorganisms in the sediment, promoting the degradation of organic matter and denitrification, achieving long-term remediation. Furthermore, this composite remediation agent also has the function of adsorbing and fixing phosphorus, while simultaneously achieving microbial phosphorus removal through the enrichment of polyphosphate-accumulating bacteria.

[0066] 1. Selection and modification of oxygen-releasing agents: The inorganic peroxide is selected from one or more of CaO2, MgO2, Na2CO4, and Na2O2. Calcium peroxide is preferred because it has a low oxygen release rate and a long continuous release time, high oxygen content, and low cost.

[0067] The inorganic peroxide powder was dispersed in solution A and ultrasonically dispersed for 30 min to obtain suspension B. Tetraethyl orthosilicate (TEOS) was added dropwise to suspension B, and the mixture was continuously stirred for 6-8 h in a water bath at 40-60℃. After washing and drying, the product was obtained as a calcium peroxide-silica composite material.

[0068] Solution A consists of 120 mL of anhydrous ethanol, 40 mL of deionized water, and 4 mL of concentrated ammonia (mass fraction 25-28%). The ratio of TEOS to peroxide in suspension B is 2-10 mL / g.

[0069] Loading a silica layer onto the surface of peroxide allows hydrogen peroxide, generated from the reaction of inorganic peroxide with water, to pass through the silica layer and react with sodium manganese ore to produce oxygen. This effectively alleviates the problem of excessively rapid oxygen production rate of calcium peroxide in aqueous solution, while also prolonging the interaction time between hydroxyl radicals, superoxide radicals, and other organic pollutants generated during oxygen release.

[0070] 2. Preparation of Sodium Manganese Ore: Sodium manganese ore with photoelectric effect capabilities is prepared by chemical synthesis. The preparation method involves forming manganese hydroxide (Mn(OH)₂) from a solution containing manganese salt (0.02-0.2M, such as manganese nitrate, manganese chloride, or manganese sulfate) and an alkali (0.5-2.0M, such as NaOH or KOH). Potassium permanganate (0.05-0.5M) is then introduced into this solution to oxidize Mn(OH)₂. After reacting for 12-24 hours, the resulting precipitate is filtered from the solution, washed, dried, and ground to obtain sodium manganese ore.

[0071] 3. Cultivation of functional microorganisms: Water-sodium manganese ore was added to activated sludge containing nitrates, phosphates, and organic pollutants after aeration pretreatment. Aerobic denitrifying bacteria and polyphosphate-accumulating bacteria were inoculated, and the microbial community adapted to aerobic conditions and the photoelectric effect of manganese ore was cultivated under visible light irradiation. The microbial community was a mixed aerobic denitrifying and phosphorus-removing microbial community.

[0072] 4. Mix polyvinyl alcohol, sodium alginate, and water at a mass ratio of 3-8g:1g:100mL until homogeneous, and heat at 95℃ for at least 2 hours to form a hydrogel. Add the peroxide-silica composite material and the pre-prepared sodium manganese ore at a mass ratio of 2-5:1 to the hydrogel, along with a suspension of acclimated and cultured microorganisms. Stir until homogeneous, pour into a mold, and freeze-mold to prepare block or spherical particles. Immerse the formed particles in a saturated H3BO3 solution containing CaCl2 for crosslinking for 24-72 hours, wash and air-dry to obtain a sodium manganese ore-oxygen release agent composite sediment remediation agent.

[0073] The encapsulated bacterial suspension accounts for 15%-25% of the total mass of the hydrogel. The modified oxygen-releasing agent and sodium manganese ore account for 20%-30% of the total mass of the composite material.

[0074] Using polyvinyl alcohol as a dispersant and encapsulating agent improves the dispersibility of sodium manganese ore and calcium peroxide, and encapsulates the microbial community after domestication and cultivation.

[0075] 5. Application of water-sodium manganese ore-oxygen-releasing agent composite sediment remediation agent: The water-sodium manganese ore-oxygen-releasing agent composite sediment remediation agent is spread on the mud-water interface and irradiated with sunlight, solar energy, optical fiber transmission light source, LED light source, etc. Through the photoelectric effect of water-sodium manganese ore, the synergistic effect of oxygen-releasing agent and microorganisms, pollutants are removed and the surface sediment is repaired.

[0076] To ensure remediation efficiency, the light intensity I at the mud-water interface of the water body to be remediated needs to reach 200W / m². 2 above.

[0077] The light intensity at the mud-water interface is calculated using the following formula: I = I0·e -k·d Where I is the light intensity reaching the mud-water interface, I0 is the light intensity of the light source at the water surface or underwater, k is the light attenuation coefficient, and d is the distance the light travels in the water. The light attenuation coefficient k has the following values: in clear freshwater lakes and rivers, k = 0.1-0.3m. -1 Moderately turbid water (suspended particle concentration 50-200 mg / L, turbidity 20-100 NTU), k = 0.3-1.0 m -1 Turbid water (suspended particle concentration > 200 mg / L, turbidity > 100 NTU), k > 1.0 m -1 .

[0078] Example 1: Preparation of a composite sediment remediation material consisting of sodium manganese ore and oxygen release agent.

[0079] (1) 2g of calcium peroxide powder was dispersed in a solution consisting of 120mL of anhydrous ethanol, 40mL of deionized water and 4mL of concentrated ammonia (mass fraction 25-28%), and ultrasonically dispersed for 30min to obtain a suspension. 10mL of tetraethyl orthosilicate (TEOS) was added dropwise to the above suspension, and the mixture was stirred continuously for 8h under a water bath at 60℃. After washing and drying, the modified oxygen-releasing calcium peroxide-silica composite material was obtained.

[0080] (2) Sodium manganese ore with unique photoelectric effect capabilities was prepared by chemical synthesis. The method involved forming Mn(OH)₂ from a solution containing 0.2M manganese sulfate and 0.5M NaOH, then oxidizing the Mn(OH)₂ with 0.1M potassium permanganate. After reacting for 24 hours, the resulting precipitate was filtered from the solution, washed, dried, and ground to obtain sodium manganese ore. Figure 1 As shown, the band gap of naphthoic ore is 1.77 eV, corresponding to its visible light absorption capacity; Figure 2 The photocurrent response curve shows its significant photoelectrocatalytic activity.

[0081] (3) Cultivation of microbial community: Water sodium manganese ore is added to activated sludge containing nitrate, phosphate and organic pollutants after aeration pretreatment, and aerobic denitrifying bacteria and polyphosphate-accumulating bacteria are inoculated. Under visible light irradiation, microbial community adapted to aerobic conditions and photoelectric effect of manganese ore is acclimatized and cultivated.

[0082] (4) Polyvinyl alcohol and sodium alginate were mixed at a mass ratio of 3g:1g, added to 100mL of deionized water and stirred until homogeneous. The mixture was then heated at 95℃ for at least 2 hours to form a hydrogel. Peroxide-silica composite material and pre-prepared sodium manganese ore were added to the hydrogel at a mass ratio of 5:1. Subsequently, 20mL of pre-cultured microbial suspension (containing 10...) was added. 7 -10 9 The concentration of the hydrogel (CFU / mL) was 20% of the total mass of the hydrogel. After stirring evenly, the mixture was poured into a mold and frozen to form block or spherical particles.

[0083] (5) The formed particles were soaked in a saturated H3BO3 solution containing CaCl2 for 24 hours for cross-linking. After washing and air drying, the water-sodium manganese ore-oxygen release agent composite sediment remediation material BORC was obtained.

[0084] Application Example 1: Simulation Experiment of Sediment Oxygenation Remediation

[0085] The experimental sediment was taken from Nanhu Lake in Jiaxing. The sediment was tested and found to have a water content of 82%, a pH of 7.13, a DO concentration of 2.34 mg / L, and an oxidation-reduction potential (ORP) of -58 mV.

[0086] 100 mL of sediment was placed into six 500 mL covered beakers and labeled CK, CaO2, BIR, BIR+CaO2, BIR+ORC, and BORC, respectively. ORC was an oxygen-releasing composite material made from anhydrous sodium manganese ore prepared using the same method as in Example 1.

[0087] The CK group served as the untreated blank control group.

[0088] The CaO2 group added 1g of oxygen-releasing agent CaO2 to the mud-water interface.

[0089] Add 1g of sodium manganese ore to the BIR group.

[0090] The BIR+CaO2 group consists of 1g of oxygen-releasing agent CaO2 and 1g of sodium manganese ore.

[0091] The BIR+ORC group consists of 5g of oxygen-releasing composite material and 1g of sodium manganese ore.

[0092] The BORC group is a composite sediment remediation material prepared in Example 1 with the addition of 5g of sodium manganese ore-oxygen release agent.

[0093] Subsequently, 300 mL of synthetic wastewater (10 mg / L NH4) was poured into the beaker. + -N, 10 mg / L NO3 - -N, 6 mg / L PO4 3- -P). The beaker was sealed with a transparent lid to reduce the influence of atmospheric reoxygenation and simulate the low dissolved oxygen state at the mud-water interface.

[0094] An LED light strip (800 μmol·m⁻¹) was fixed at a height of 20 cm above the liquid surface. 2 ·s -1 As a light source, the ambient temperature was approximately 20°C. The concentrations of ammonia nitrogen, nitrate nitrogen, and phosphate were continuously monitored during the reaction period of 0-120 hours. The physicochemical properties of the overlying water were monitored after 48 hours of reaction, and the total organic carbon (TOC) concentration in the sediment was measured after 10 days.

[0095] The physicochemical properties of the overlying water after 48 hours of reaction are shown in Table 1.

[0096] Table 1 Physicochemical properties of the overlying water after 48 hours of reaction.

[0097]

[0098] As shown in Table 1, the introduction of CaO2 or sodium manganese ore (BIR) can increase the redox potential of the aqueous solution, enhance the oxidation of reducing substances, and reduce the consumption of dissolved oxygen (DO). The addition of CaO2 significantly increases the solution pH. BIR, while promoting oxygen utilization through the photoelectric effect, effectively neutralizes the alkalinity released by CaO2, enhancing pH stability. The oxygen-releasing agent ORC can slow down the alkalinity release process by releasing oxygen, improving the microbial environment of the surface sediments. Example 1 demonstrates that the prepared sodium manganese ore-oxygen-releasing agent composite sediment remediation material BORC has significant effects on reducing overlying water turbidity, increasing dissolved oxygen levels, stabilizing the pH of the aquatic environment, and increasing the redox potential. After adding BORC, the overlying water turbidity decreased from 27.28 NTU to 3.378 NTU, and the DO increased to 4.91 mg / L.

[0099] Figure 3 , Figure 4 The effects of adding different remediation agents on the ammonia nitrogen and nitrate nitrogen concentrations in the overlying water were investigated, for example... Figure 3 , 4 As shown, the addition of composite sediment remediation material BORC significantly accelerated the removal process of ammonia nitrogen and nitrate nitrogen in the overlying water, with removal rates of 97% and 82% respectively after 72 hours of reaction.

[0100] During the 120-hour reaction period, adding BIR and CaO2 simultaneously to the sediment, or directly adding BORC, can increase the NO3 content in the overlying water. -The -N removal rate was significantly improved to over 95% compared to less than 40% in the blank control group. Figure 5 The total organic carbon (TOC) content in the sediment of each treatment group after 10 days of reaction was shown. The TOC content in the sediment of the BORC group decreased to about half of the initial value.

[0101] The BIR photoelectric effect enriches the electron transfer pathways of the system, enhances the effectiveness of CaO2 oxygen release, accelerates the nitrification and denitrification process, and promotes the degradation and transformation of recalcitrant organic matter. Figure 6 This is a diagram illustrating the mechanism of action of the sodium manganese ore-oxygen release agent composite sediment remediation material, including the photoelectric effect of sodium manganese ore and its synergistic enhancement of the degradation of organic matter, removal of ammonia nitrogen, and denitrification in contaminated sediment.

[0102] Therefore, the sodium manganese ore-oxygen-releasing agent composite sediment remediation material of the present invention combines the photoelectric effect of sodium manganese ore with the oxygen-releasing capacity of the oxygen-releasing agent to improve the photocatalytic activity of sodium manganese ore, enhance its continuous degradation ability of organic pollutants, and promote simultaneous denitrification and phosphorus removal, in-situ remediation of sediment through the synergistic effect of multiple components, improve the redox potential of sediment, synergistically remove pollutants from sediment and aquatic environment, and improve the ammonia removal efficiency of sediment.

[0103] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes or modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions should also fall within the scope of the invention and should be defined by the claims.

Claims

1. A water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material, characterized in that, It includes a modified oxygen-releasing agent, sodium manganese ore, microbial community and embedding matrix. The embedding matrix includes a hydrogel formed by cross-linking calcium alginate, polyvinyl alcohol and water. The microbial community includes a domesticated aerobic denitrification and phosphorus removal mixed community. The modified oxygen-releasing agent is a modified oxygen-releasing compound with a silica layer loaded on the surface of a peroxide. The peroxide is CaO2; The aerobic denitrification and phosphorus removal mixed bacterial community is an aerobic denitrification and phosphorus removal mixed bacterial community inoculated from activated sludge, which has been acclimatized and cultured under aerobic conditions and photoelectric effect by water sodium manganese ore and light source irradiation.

2. The water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material according to claim 1, characterized in that, The combined mass of the modified oxygen-releasing agent and sodium manganese ore accounts for 50-80% of the total mass of the composite sediment remediation material, and the mass ratio of the modified oxygen-releasing agent to sodium manganese ore is 2-5:

1.

3. The composite sediment remediation material according to claim 1, characterized in that, The method for preparing the modified oxygen-releasing agent, Includes the following steps, (1) Disperse the peroxide powder in a solution composed of anhydrous ethanol, deionized water and concentrated ammonia, and ultrasonically disperse for 15-50 min to obtain a suspension; (2) Tetraethyl orthosilicate (TEOS) was added dropwise to the suspension and stirred continuously for 6-8 hours in a water bath at 40-60°C. After washing and drying, the product was obtained as a modified oxygen-releasing compound.

4. The composite sediment remediation material according to claim 3, characterized in that, The concentration of the concentrated ammonia solution is 25-28 wt%, the volume ratio of anhydrous ethanol, deionized water and concentrated ammonia solution is 20-40:5-20:0.1-5, and the ratio of tetraethyl orthosilicate to peroxide is 2-10 ml:1 g.

5. The water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material according to claim 1, characterized in that, The method for preparing sodium manganese ore, Includes the following steps, (1) A manganese hydroxide Mn(OH)2 solution is obtained by mixing a 0.02-0.2 M manganese salt solution and a 0.5-2.0 M alkaline solution; (2) Add 0.05-0.5M potassium permanganate solution to manganese hydroxide Mn(OH)2 solution, react for 12-24h, filter out the precipitate from the solution, wash and dry it, grind it to obtain sodium manganese ore.

6. A method for preparing the water-sodium manganese ore-oxygen release agent composite sediment remediation material as described in claim 1, characterized in that, Includes the following steps, (1) Mix polyvinyl alcohol, sodium alginate and water evenly, and heat at 80-110℃ for 1-2 hours or more to form a hydrogel; (2) Add the modified oxygen-releasing agent and sodium manganese ore to the hydrogel, then add the domesticated and cultured microbial suspension, stir evenly, pour into the mold, and freeze to form; (3) The frozen material obtained in step (2) is immersed in a saturated H3BO3 solution containing CaCl2 for 24-72 h, washed and air-dried to obtain a water-sodium manganese ore-oxygen release agent composite sediment remediation material.

7. The preparation method according to claim 6, characterized in that, The ratio of polyvinyl alcohol, sodium alginate, and water is 3-8g:1g:50-200mL; The ratio of sodium manganese ore and microbial suspension used is 1g:15-25ml. The concentration of the microbial suspension was 10. 7 -10 9 The CFU / mL concentration of the microbial suspension accounts for 15%-25% of the total mass of the hydrogel.

8. A method for applying the water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material as described in claim 1 or the water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material prepared by the preparation method described in claim 6, characterized in that, The water-sodium manganese ore-oxygen-releasing agent composite sediment remediation material is laid on the mud-water interface to be remediated. With the help of at least one light source such as sunlight, solar energy, optical fiber transmission light source, or LED light source, the photoelectric effect of water-sodium manganese ore is activated by light, which, together with the oxygen-releasing function of the oxygen-releasing agent and the metabolic action of microorganisms, remediates nitrogen, phosphorus and organic matter in the sediment.

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