A full solid waste-based water treatment material and a preparation method and application thereof

Abstract

The application discloses a kind of full solid waste base water treatment materials and its preparation method and application, which is made of the following mass percentage of raw materials: scrap iron: 20~25%;Steel slag: 30~40%;Non-dangerous waste waste activated carbon: 15~20%;Engineering slurry dry powder: 15~20%;Waste glass: 5~8%;Waste wood fiber: 5~10%;The application is by using specific proportion of raw materials, the various solid wastes that originally need to be paid disposal are converted into high-performance water treatment functional materials, realizes "waste treatment", fundamentally subverts the high-cost mode of traditional water treatment materials depending on commodity raw materials, comprehensive porous adsorption, iron-carbon micro-electrolysis and biological membrane and other various phosphorus removal principles, synergistically exert their respective advantages, it is a kind of efficient, long-acting, stable and environment-friendly full solid waste water treatment material, it has important significance for promoting the green development of water treatment industry and reducing treatment cost.

Description

Technical Field

[0001] This application relates to the field of water treatment technology, and in particular to an all-solid waste-based water treatment material, its preparation method, and its application. Background Technology

[0002] Eutrophication is a serious challenge to water environment management, and phosphorus, as a key limiting factor, requires efficient and economical removal to solve the problem. Currently, mainstream phosphorus removal technologies all have significant limitations and cannot meet the needs of green and sustainable governance.

[0003] While adsorption methods are simple to operate, conventional materials relying on physical adsorption (such as activated alumina and zeolite) have limited adsorption capacity, requiring frequent regeneration after saturation. Furthermore, the regeneration process leads to a continuous decline in adsorption performance, ultimately generating large amounts of solid waste. Chemical precipitation methods (adding aluminum or iron salts) are fast-acting, but they introduce foreign anions such as chloride and sulfate into the water, posing long-term environmental risks. Additionally, the cost of chemical addition is high, and the resulting chemical sludge is large and difficult to treat. Biological methods (including biofilm methods) are sensitive to operating conditions; their treatment effectiveness is unstable under low phosphorus concentrations or fluctuating water quality and quantity, and they suffer from problems such as biofilm clogging and low mass transfer efficiency.

[0004] In recent years, iron-carbon microelectrolysis materials have attracted attention due to their ability to continuously release ferric ions, which have a flocculation and phosphorus removal effect. However, traditional iron-carbon materials use commercial iron powder and activated carbon as raw materials, which are costly; moreover, during the reaction process, the surface deposition of iron oxides and hydroxides leads to rapid passivation and caking of the material; and the biofilm formed during long-term operation further hinders the microelectrolysis reaction, resulting in a short effective lifespan of the material and the inability to achieve deep and long-term phosphorus removal.

[0005] On the other hand, the problem of stockpiling various types of solid waste is prominent. In particular, steel slag, due to its complex composition and poor stability, has low added value in existing utilization methods (such as road construction and backfilling), and the bottleneck of resource utilization is difficult to overcome. At the same time, waste activated carbon, engineering mud, waste glass, and waste wood fiber also face the dilemma of low-value disposal.

[0006] Therefore, there is an urgent need in this field for a new type of water treatment material and technology that can comprehensively and synergistically remove phosphorus through multiple mechanisms, overcome the shortcomings of existing materials that are prone to passivation, and realize the high-value utilization of various solid wastes. Summary of the Invention

[0007] To address the aforementioned issues, this application integrates multiple phosphorus removal principles, including porous adsorption, iron-carbon micro-electrolysis, and biofilm, leveraging their respective advantages. Utilizing low-cost solid waste as raw material, it provides a highly efficient, long-lasting, stable, and environmentally friendly all-solid wastewater treatment material, its preparation method, and its application. This is of great significance for promoting the green development of the water treatment industry and reducing treatment costs. The technical solution is as follows:

[0008] The first aspect of this application provides a solid waste-based water treatment material, made from the following raw materials by weight percentage: waste iron filings: 20-25%; steel slag: 30-40%; non-hazardous waste activated carbon: 15-20%; dry engineering mud powder: 15-20%; waste glass: 5-8%; waste wood fiber: 5-10%.

[0009] For example, in the all-solid waste-based water treatment material provided in one embodiment, the waste iron filings are at least one of steel sandblasting iron powder, grinding iron powder or machining iron filings, and have undergone magnetic separation and degreasing treatment; the waste wood fiber is derived from waste wooden templates, straw or rice husks, and its particle size is controlled between 0.1 and 1 mm.

[0010] For example, in one embodiment of the all-solid waste-based water treatment material, the material is spherical particles with a diameter of 5 to 8 mm and longitudinal and transverse grooves with a depth of 1 to 2 mm distributed on its surface.

[0011] For example, in one embodiment of the all-solid waste-based water treatment material, the material has a closed-cell structure formed by the gas generated from the decomposition of waste wood fiber and the reduction of iron oxide in steel slag being enveloped by a high-temperature liquid phase; and zero-valent iron particles and carbon particles are covered and fixed by a silicate network skeleton formed by solidification, constituting a micro-electrolysis unit inside the material.

[0012] For example, in one embodiment of the all-solid waste-based water treatment material, the silicate network framework is derived from calcium silicate minerals in steel slag and low-melting-point deposits formed at high temperatures by waste glass and engineering slurry.

[0013] The second aspect of this application provides a method for preparing a solid waste-based water treatment material, comprising the following steps: Step S1, raw material pretreatment: degreasing waste iron filings, dehydrating and drying engineering slurry, and crushing all large raw materials to less than 5 mm; Step S2, raw material grinding: weighing the pretreated raw materials according to the formula ratio, and putting them into a ball mill for co-ultra-fine grinding to make the material fineness ≥300 mesh; Step S3, mixing and molding: adding 6-10% of the total mass of water to the ground material, mixing evenly, and pressing into shape to obtain a green body; Step S4, anaerobic calcination: calcining the green body under nitrogen protection using a programmed temperature control method, the programmed temperature control calcination including: heating from room temperature to 300°C at 3-5°C / min, then heating to 700°C at 5°C / min and holding for 20-30 min, then heating to 1120°C at 5°C / min and holding for 15-30 min, and finally quenching to room temperature by introducing nitrogen.

[0014] For example, in one embodiment of the method for preparing all-solid waste-based water treatment materials, in step S2, the waste wood fiber is added in two stages, of which 50% is fed into a ball mill together with other raw materials for grinding, and the remaining 50% is added in the mixing stage of step S3.

[0015] For example, in one embodiment of the method for preparing all-solid waste-based water treatment materials, the strength of the green blank obtained by pressing in step S3 is sufficient to prevent it from breaking when dropped freely from a height of 1 meter.

[0016] For example, in one embodiment of the method for preparing all-solid waste-based water treatment materials, the calcination process in step S4 utilizes the waste heat from steel slag in a steel plant as a heat source.

[0017] The third aspect of this application provides an application of a solid waste-based water treatment material in wastewater treatment, wherein the material is subjected to targeted inoculation with polyphosphate-accumulating bacteria to construct an iron-carbon-biofilm coupled phosphorus removal system to achieve deep phosphorus removal.

[0018] Compared with existing technologies, the all-solid waste-based water treatment materials, their preparation methods, and applications provided in this application bring the following significant benefits:

[0019] (1) It has achieved a fundamental reduction in the resource utilization and treatment costs of solid waste: By using a specific ratio of waste iron filings, steel slag, waste activated carbon, engineering mud, waste glass and waste wood fiber as all raw materials, a variety of solid wastes that originally required paid disposal have been transformed into high-performance water treatment functional materials, realizing "waste treatment with waste". This not only solves the problem of solid waste disposal, but also reduces the cost of raw materials to an extremely low level, and even generates negative costs by charging treatment fees or obtaining subsidies, fundamentally subverting the high-cost model of traditional water treatment materials that rely on commodity raw materials.

[0020] (2) A long-lasting, deep phosphorus removal system with multiple synergistic mechanisms was constructed: Through material formulation and special process design, micro-electrolysis units and multi-level porous structures fixed by a silicate framework were formed in situ inside the material. This structure simultaneously performs three functions: physical adsorption, micro-electrolysis chemical phosphorus removal, and biofilm carrier. The Fe produced continuously by micro-electrolysis... 2 ⁺ / Fe 3 ⁺ It achieves chemical phosphorus removal and flocculation; the porous structure provides an ideal carrier for polyphosphate-accumulating bacteria biofilm, enabling biological phosphorus uptake; the three work synergistically to form a deep phosphorus removal channel coupled with "chemical-biological" processes, ensuring the high efficiency and durability of the treatment effect.

[0021] (3) The structural design overcomes the technical bottleneck of easy passivation of iron-carbon materials: the unique microstructure allows the silicate network skeleton to both encapsulate and fix iron-carbon particles and form a semi-permeable barrier. This structure allows water molecules and phosphate ions to enter and react with iron, but effectively hinders the deposition and migration of reaction products (such as Fe(OH)3) on the surface of iron particles, thus significantly slowing down the formation rate of the passivation layer. At the same time, the grooves on the surface of the spherical particles and their mutual friction in the water flow can automatically clean the aged biofilm and covering on the surface, realizing the self-renewal of the material surface and enabling it to maintain high reactivity for a long time.

[0022] (4) Achieving pore formation, activation, and structural stability simultaneously through an integrated process: The key "oxygen-deficient roasting" process and specific temperature curve simultaneously achieve the three major goals of "pore formation," "generation of active elemental iron," and "formation of a stable framework" in one process. Iron oxides in steel slag are reduced in situ by carbon to generate highly active zero-valent iron; the decomposition and reduction reaction of wood fibers produce gas, which is encapsulated by the simultaneously formed molten liquid phase, forming closed pores; after the liquid phase cools, it solidifies to form a robust silicate framework. This process avoids the complexity and high energy consumption of multi-step processing, and the highly active phase is "frozen" and preserved through a rapid cooling process, ensuring product performance.

[0023] (5) Expanded functional boundaries and enhanced environmental friendliness: When applying the material, a coupling system is constructed by inoculating polyphosphate bacteria. The active hydrogen atoms [H] and electrons generated during the micro-electrolysis process can serve as electron donors for denitrifying bacteria, providing a new denitrification denitrification pathway for low-carbon water bodies without the need for external carbon sources, and simultaneously enhancing the denitrification and phosphorus removal effects. At the same time, the entire water treatment process does not require the addition of chemical agents, does not introduce external harmful ions, produces less sludge with a high phosphorus content, and can be recycled as a phosphorus resource, thus achieving environmental friendliness and resource recycling throughout the entire process.

[0024] (6) Improved the economy and universality of the production process: The use of waste heat from steel slag in steel plants for roasting significantly reduced energy consumption and made large-scale industrial production more economically feasible. The requirements for raw material pretreatment and green billet strength ensured the smoothness of the production process and the yield of finished products, laying a solid foundation for the industrialization and promotion of the technology. Attached Figure Description

[0025] none Detailed Implementation

[0026] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0027] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art to which this disclosure pertains. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that the element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects. Terms such as “connected” or “linked” are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as “upper,” “lower,” “left,” and “right” are used only to indicate relative positional relationships, and these relative positional relationships may change accordingly when the absolute position of the described objects changes.

[0028] Example 1: Preparation of all-solid waste-based water treatment materials

[0029] Raw material preparation and pretreatment

[0030] Prepare raw materials according to the following mass percentages:

[0031] Scrap iron filings (including at least one of steel sandblasting powder, grinding powder, or machining filings, and treated with magnetic separation and degreasing): 23%;

[0032] Steel slag (tested to be non-hazardous waste): 35%;

[0033] Non-hazardous waste activated carbon (mainly waste activated carbon from the food industry, etc. Activated using an activation device to remove substances and moisture, facilitating grinding and preventing the generation of polluting gases during roasting): 18%;

[0034] Dry engineering mud powder (derived from the mud cake after dewatering and drying of pipe jacking mud, piling mud, or shield tunneling mud): 17%;

[0035] Waste glass (sourced from municipal solid waste sorting centers, construction waste recycling plants, etc.): 6%;

[0036] Waste wood fiber (derived from waste wooden formwork, straw, or rice husks, with a particle size controlled between 0.1 and 1 mm): 8%;

[0037] Added water: 6-10% of the total dry mass.

[0038] The above raw materials were pretreated as follows: large pieces of steel slag, dry powder of engineering mud, and waste glass were initially crushed to <5mm; the surface grease of the machined iron filings was removed by high-temperature roasting; the engineering mud was dewatered by plate and frame filter press and then dried at 105℃ to constant weight.

[0039] By defining a material system composed of six solid wastes in specific mass percentages, the direct effect is the realization of a "waste-to-waste" circular economy model, transforming bulk industrial and municipal solid waste into high-value-added environmental materials at extremely low or even negative raw material costs. More importantly, the components are not simply mixed in subsequent processes, but rather work synergistically through physicochemical reactions to jointly construct a composite material that combines physical adsorption, chemical phosphorus removal, and biological carrier functions, laying the material foundation for the subsequent formation of a long-lasting, multi-stage phosphorus removal system.

[0040] By limiting the source and pretreatment requirements of waste iron filings, as well as the source and particle size of waste wood fibers, the purity and reactivity of the core reactive component (iron) were ensured. Simultaneously, by controlling the particle size of the wood fibers, the final size and distribution of the internal pores in the material were precisely regulated. This ensures that the material can form an ideal porous structure during the calcination process, enabling the micro-electrolysis reaction to proceed efficiently and stably.

[0041] Raw material grinding

[0042] All pretreated raw materials (50% of the total amount of crushed rice husks were added first) were put into a ball mill for joint ultrafine grinding. High chromium steel balls were used as the grinding media and the materials were ground together to a fineness of ≥300 mesh.

[0043] Mixing and pressing

[0044] The ground powder was transferred to a high-efficiency mixer, and the remaining 50% waste wood fiber was added and mixed evenly. Then, 8% (by weight of the total dry material) of clean water was slowly added, and the mixture was stirred for 15 minutes until the material had uniform moisture content. By using a two-stage addition process of waste wood fiber, the gradient design and functional optimization of the material's internal pore structure were achieved. The first 50% was ball-milled to form a fine carbon source, which was evenly dispersed, facilitating the reduction reaction and the formation of micropores. The second 50% was added during mixing as a macroscopic pore-forming agent, forming larger channels after calcination and decomposition. This multi-level pore structure not only facilitates reaction mass transfer but also provides habitats for microorganisms at different scales, optimizing the synergistic effect of "micro-electrolysis-biofilm".

[0045] The mixed materials are fed into a disc granulator and pressed into spherical pellets with a diameter of 6 mm. Interlaced grooves approximately 1.5 mm deep are then pressed into the surface of the pellets. The pressed green body has sufficient strength to withstand a free drop from a height of 1 meter without breaking.

[0046] By defining the material as spherical particles of a specific diameter with fine grooves, the specific surface area of ​​the material is significantly increased, providing a superior carrier for microbial attachment. The grooves on the surface facilitate biofilm formation, while the spherical structure and specific size give it excellent fluidization and mutual friction properties in water, effectively and automatically peeling off aged biofilms and surface passivation layers, thus maintaining the activity of the material surface and solving the technical problems of easy caking and passivation of traditional iron-carbon materials. By limiting the mechanical strength of the green body, the effect is to ensure that the unsintered green bodies will not break during subsequent handling and stacking, guaranteeing the yield and shape regularity of the product. This is an important process guarantee for achieving large-scale, continuous industrial production, avoiding production interruptions and material losses due to insufficient green body strength.

[0047] Maintenance and Drying

[0048] The molded wet granules were cured at room temperature (25℃) and relative humidity (60%) for 24 hours to allow them to dry naturally.

[0049] anaerobic roasting

[0050] The dried green bodies are evenly stacked on kiln cars and pushed into a tunnel kiln for programmed temperature-controlled firing. High-purity nitrogen is circulated throughout the process as a protective gas to maintain a slightly positive pressure, oxygen-deficient environment inside the kiln.

[0051] The specific temperature control procedure is as follows: The temperature is increased from room temperature to 300℃ at a rate of 4℃ / min to fully remove physical moisture; then increased to 700℃ at a rate of 5℃ / min and held for 25 minutes to allow for complete decomposition of the wood fibers and the reduction of iron oxide in the steel slag; finally, the temperature is increased to 1120℃ at a rate of 5℃ / min and held for 20 minutes. The core objective is to form a liquid phase, achieve sintering, fix the pore structure, and complete the melting of eutectic materials in the waste glass and slag, forming a viscous liquid phase. This liquid phase encapsulates elemental iron and activated carbon, forming micro-electrolysis units. The liquid phase binds the solid particles together, forming a high-strength network. The gases produced by the decomposition and reduction reactions of wood fibers are encapsulated by the liquid phase, forming closed pores. Insulation allows the liquid phase to distribute evenly, ensuring thorough sintering and homogenization of the composition. The holding time should not be too long to prevent over-sintering, which could lead to pore closure and iron particle growth. After the holding period, a high flow rate of nitrogen is immediately introduced for rapid cooling, bringing the material to room temperature within 30 minutes. This process separates the high-temperature active mineral phases (such as C2S) and reduced iron (Fe). 0 Preserve it to prevent it from decomposing or oxidizing.

[0052] By defining the material's key microstructure—closed pores and micro-electrolysis units fixed by a framework—the following effects are achieved: the closed-pore structure endows the material with a certain degree of buoyancy, promoting its fluidization in water; while the silicate network framework mechanically locks in iron and carbon particles, ensuring the long-term physical stability of countless micro-electrolysis cells and preventing iron-carbon separation failure due to water erosion. Simultaneously, this framework acts as a semi-permeable barrier, allowing water molecules and contaminants to enter the reaction while, to a certain extent, hindering the back-deposition of reaction products (such as iron oxides). Therefore, the structural design slows down the material's passivation rate and significantly extends its service life.

[0053] The silicate network framework is derived from eutectic materials formed from steel slag, waste glass, and engineering slurry. Its advantage lies in achieving "self-bonding" and "self-melting" using the solid waste's own components, eliminating the need for expensive binders and fluxes. This not only reduces costs, but more importantly, the liquid phase formed by these solid waste components at high temperatures has suitable viscosity, perfectly encapsulating the reactant gases to form closed pores and effectively encapsulating iron particles to inhibit their sintering and growth at high temperatures, thus preserving highly active elemental iron and improving micro-electrolysis efficiency.

[0054] By defining a preparation method that includes "anaerobic roasting" and a specific temperature profile, the effect is that multiple key objectives are achieved simultaneously in a single process. In the 300-700℃ stage, wood fibers decompose to create pores and provide a reducing atmosphere; in the 700℃ holding stage, iron oxides in the steel slag are fully reduced, generating highly active zero-valent iron micro-electrolysis units in situ; in the 1120℃ heating and holding stage, the desired silicate liquid-phase framework is formed and the pore structure is fixed; the final nitrogen quenching separates the highly active mineral phases (such as C2S) and reduced iron (Fe) at high temperatures. 0 The product is "frozen" to prevent it from being oxidized and deactivated during the cooling process, thus ensuring the excellent chemical and physical properties of the final product.

[0055] Product Selection

[0056] After the roasted product is cooled, particles with a diameter of 5-8mm are selected by vibration screening as the final product and packaged for later use.

[0057] The all-solid waste-based water treatment material and its preparation method disclosed in this application have the following advantages:

[0058] 1. Multifunctional synergy of materials

[0059] The components are not simply mixed, but play multiple roles in the system, producing a synergistic effect of "1+1>2", turning disadvantages into advantages and realizing waste reuse.

[0060] Steel slag: functions as an iron source, structural framework, foaming agent (forming closed pores), flux, and alkalinity regulator. Wood fiber: acts as both a pore-forming agent and a supplementary carbon source. Engineering slurry: serves as a binder, adsorption matrix, and structural framework. Waste activated carbon: acts as both a carbon source and adsorption matrix. Waste glass: acts as a flux, binder, and structural framework.

[0061] Specifically, this manifests as follows:

[0062] 1) Provide the air source required for foaming.

[0063] Steel slag is rich in FeO and Fe2O3. Under an oxygen-deficient roasting environment, when the temperature rises above 700℃, it will undergo a violent reduction reaction with the carbonaceous materials in the formula:

[0064] C + FeO → Fe + CO↑

[0065] 3C + 2Fe₂O₃ → 4Fe + 3CO₂↑

[0066] Large amounts of CO and CO2 gases are generated, and the carbonization process of wood fibers also produces a large amount of gas. At this time, the molten liquid phase formed by the components such as waste glass, clay, and steel slag at high temperature has a suitable viscosity, which can encapsulate these gases and form a large number of closed pores.

[0067] 2) Contains its own flux, reducing sintering temperature.

[0068] CaO, MgO, and FeO in steel slag are themselves strong fluxing components. They can form eutectic mixtures with waste glass and clay, effectively lowering the melting temperature of the entire mixture. Simultaneously, they solve the stability problem of free CaO and free MgO, turning a disadvantage into an advantage. This allows the material matrix to generate sufficient liquid phase viscosity at a relatively low calcination temperature (approximately 1100℃), successfully encapsulating the gases produced by the reduction reaction and avoiding the cost of adding additional flux.

[0069] 3) Simultaneous generation of active elemental iron

[0070] The reduction reaction of iron oxide and carbon in steel slag produces zero-valent iron (Fe). 0 This means that while creating pores, active iron components necessary for the micro-electrolysis reaction are generated in situ inside the material. These newly formed iron particles have high dispersion and strong activity, and are in full contact with carbon, forming highly efficient micro-electrolysis units.

[0071] 4) Forming a structural framework to stabilize the micro-electrolysis unit

[0072] At high temperatures, dicalcium silicate (C2S), tricalcium silicate (C3S), and eutectic compounds formed in steel slag with waste glass, clay, and other components produce a liquid phase. Upon cooling, this liquid phase solidifies to form a rigid, continuous network framework. This framework mechanically holds iron and carbon particles in specific locations, ensuring a lasting and close contact between them and preventing separation due to water erosion during use, thus stabilizing countless micro-electrolytic cells.

[0073] 5) Inhibits iron particle sintering and increases effective iron content.

[0074] The molten silicate phase coats the surface of fine iron particles, effectively blocking direct contact between iron particles and preventing them from melting together and growing into dense iron clumps at high temperatures. This allows the system to retain a large number of highly dispersed and highly active fine iron particles after calcination, greatly increasing the proportion and surface area of ​​"effective iron" that can be used in micro-electrolysis reactions.

[0075] 6) Adjust the reaction interface to delay passivation.

[0076] The stable silicate framework is not completely dense; it forms a complex microporous channel system. This system allows water molecules and phosphate ions (PO4) to pass through. 3 ⁻) It slowly penetrates and reacts with iron, while to a certain extent hindering the migration and deposition of reaction products (such as Fe(OH)3 flocs), thereby slowing down the formation rate of the passivation layer on the iron surface and extending the reaction life of the material.

[0077] 7) Provide an alkaline environment and chemical phosphorus removal

[0078] Dicalcium silicate (C2S) and tricalcium silicate (C3S) in steel slag are slow-hydrating active minerals that will continue to slowly hydrate in an aquatic environment: 2CaO·SiO2 + 2H2O → Ca(OH)2 + CaO·SiO2·H2O, releasing Ca... 2 ⁺ and OH⁻, Ca 2 ⁺ with phosphate (PO4) in water 3 The reaction produces a stable hydroxyapatite (Ca5(PO4)3(OH)) precipitate, and OH⁻ can continuously neutralize H⁺, ensuring that micro-electrolysis continues to be efficient and more conducive to the formation of iron phosphate precipitate.

[0079] 2. Significant environmental benefits

[0080] It simultaneously absorbs various solid wastes (metallurgical waste, industrial waste, construction waste, and agricultural waste) and transforms them into high-value-added water treatment materials, achieving waste-to-waste treatment and aligning with the concepts of circular economy and zero-waste cities.

[0081] Through a high-temperature roasting process, heavy metals are fixed and organic pollutants are decomposed, ensuring the environmental safety of the final product and preventing secondary pollution. During water treatment, no chemical agents are required, and no Cl⁻ or SO₄²⁻ is introduced. 2 ⁻、Al 3 The presence of foreign ions such as ⁺ is environmentally friendly.

[0082] 3. Superior performance

[0083] The three-in-one phosphorus removal mechanism of "physical adsorption + micro-electrolysis chemical precipitation + micro-electrolysis biofilm coupling" ensures efficient, deep and long-lasting phosphorus removal capabilities, while producing less sludge and producing high phosphorus content in the precipitate, which can be used for phosphorus resource recovery and utilization.

[0084] The iron-carbon porous structure can adsorb organic matter in water, providing a good carrier for biofilm formation. The biofilm can effectively capture organic matter and phosphorus in the water. Simultaneously, the micro-electrolysis product Fe... 3 The flocculation effect of ⁺ can "net" and enrich dispersed organic matter and colloidal particles around the biofilm, providing a rich food source for polyphosphate-accumulating bacteria in the biofilm.

[0085] The porous iron-carbon structure and biofilm create an anaerobic / anoxic microenvironment, which perfectly meets the process conditions for polyphosphate-accumulating bacteria to "anaerobic phosphorus release-aerobic phosphorus uptake," enabling them to absorb excessive amounts of phosphorus from the water. Simultaneously, the iron ions generated by iron-carbon microelectrolysis can readily bind with phosphorus, further promoting the production of iron ions through iron-carbon microelectrolysis.

[0086] The porous structure floats in water and, through friction caused by water flow, prevents the formation of surface biofilms and passivation layers, thus solving the problem of electrolysis efficiency being affected by traditional iron-carbon caking and biofilm formation, ensuring continuous and efficient iron-carbon micro-electrolysis. Simultaneously, the mutual friction effectively removes the surface portion of the biofilm from the pits on the porous iron-carbon surface, maintaining biofilm activity.

[0087] The active hydrogen atoms [H] and electrons (e⁻) continuously generated by the micro-electrolysis reaction are strong reducing agents and can be directly used as electron donors for denitrifying bacteria to reduce nitrate (NO⁻) to nitrogen (N₂). This provides a denitrification pathway that does not rely on organic carbon sources. For river and lake waters with low carbon-to-nitrogen ratios, it greatly enhances the system's nitrogen removal capacity without the need for external carbon sources (such as methanol or sodium acetate), avoiding secondary pollution and cost issues. It achieves phosphorus removal while simultaneously enhancing nitrogen removal. The nascent [H] and nascent Fe generated during the micro-electrolysis process... 2 ⁺ It possesses high reactivity, capable of chain breaking and ring opening, disrupting the molecular structure of some recalcitrant organic compounds and transforming them into smaller, more readily biodegradable organics. This improves the biodegradability of water (B / C ratio), clearing obstacles for subsequent biofilm treatment and enabling the entire system to achieve a broader spectrum of removal efficiency for complex pollutants.

[0088] 4. Economic efficiency

[0089] All raw materials are solid waste, readily available, and extremely low-cost, even negative-cost (by charging processing fees or receiving government subsidies). Using scrap iron powder and iron filings can reduce some of the grinding energy consumption. Compared to purchasing commercial raw materials (such as new iron powder, new activated carbon, and bentonite), costs can be reduced by 1 to 2 orders of magnitude.

[0090] The crushing, grinding, shaping, and roasting processes used are all mature unit operations, which are easy to scale up for production.

[0091] By collaborating with steel mills and utilizing the waste heat from steel slag, energy costs are significantly reduced. The direct effect of using the waste heat from steel slag for roasting is a substantial reduction in energy costs during production, making this material, made from solid waste, more economically competitive. Simultaneously, this achieves a seamless integration of the steel production process with the production process of solid waste resource-based products, representing a profound embodiment of the circular economy concept at the production technology level.

[0092] Because porous iron-carbon materials can float in water, the friction caused by water flow makes maintenance simple and enables continuous and efficient operation without power, achieving zero-energy operation.

[0093] Compared with chemical phosphorus removal, the material produced in this application produces less sludge and has a higher phosphorus content, which can be utilized as a phosphorus resource, thus solving the problems of difficult and expensive sludge treatment using conventional chemical methods.

[0094] For water body treatment, nitrogen and organic pollutants in the water body are removed simultaneously while removing phosphorus.

[0095] Example 2: Application of materials in wastewater treatment

[0096] Before use, the prepared solid waste-based water treatment material is inoculated with polyphosphate-accumulating bacteria to form an iron-carbon-biofilm coupled phosphorus removal system for deep phosphorus removal. The bacterial strains are derived from native strains and have been cultivated and domesticated. The material is placed in the water to be treated containing polyphosphate-accumulating bacteria and aerated to form a biofilm. By inoculating the material with polyphosphate-accumulating bacteria to construct the coupled system, the effect is to organically combine the physical adsorption characteristics of the material, the chemical phosphorus removal and flocculation characteristics of micro-electrolysis, and the superphosphate uptake characteristics of the biofilm. Micro-electrolysis creates an anaerobic / aerobic alternating microenvironment for polyphosphate-accumulating bacteria and provides electron donors, while the biofilm can continuously utilize organic matter in the water and fix phosphorus, forming a self-driven and self-sustaining deep phosphorus removal system. This achieves continuous, efficient, and stable removal of phosphorus from the water and significantly reduces sludge production.

[0097] Solid waste-based water treatment materials can be applied to various scenarios, including deep phosphorus removal after secondary biochemical treatment in municipal sewage treatment plants, phosphorus removal in rivers and lakes, treatment of black and odorous water bodies and landscape water, pretreatment of industrial wastewater, and decentralized sewage treatment in rural areas.

[0098] After the materials are used, 8-15% should be replenished annually based on consumption. For materials that are worn down to fine particles that are no longer able to float, they should be removed along with phosphorus-containing precipitates to prepare organic fertilizer or soil conditioner, or separated and used as raw materials.

[0099] Although the embodiments of this application have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for this application. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, this application is not limited to the specific details.

Claims

1. A solid waste-based water treatment material, characterized in that, It is made from the following raw materials by weight percentage: waste iron filings: 20-25%; steel slag: 30-40%; non-hazardous waste activated carbon: 15-20%; dry engineering mud powder: 15-20%; waste glass: 5-8%; waste wood fiber: 5-10%. The method for preparing the all-solid waste-based water treatment material includes the following steps: Step S1, Raw material pretreatment: Degrease the waste iron filings, dehydrate and dry the engineering mud, and crush all large pieces of raw materials to less than 5mm; Step S2, Raw material grinding: Weigh the pretreated raw materials according to the formula ratio, put them into a ball mill for joint ultrafine grinding, so that the fineness of the material is ≥300 mesh; Step S3, Mixing and Molding: Add 6-10% water by weight of the ground material to the ground material, mix evenly, and then press to form a green body. Step S4, Oxygen-deficient calcination: The green body is subjected to programmed temperature-controlled calcination under nitrogen protection. The programmed temperature-controlled calcination includes: heating from room temperature to 300°C at a rate of 3-5°C / min, then heating to 700°C at a rate of 5°C / min and holding for 20-30 min, then heating to 1120°C at a rate of 5°C / min and holding for 15-30 min, and finally quenching to room temperature by introducing nitrogen.

2. The all-solid waste-based water treatment material according to claim 1, characterized in that, The waste iron filings are at least one of steel sandblasting iron powder, grinding iron powder, or machining iron filings, and have undergone magnetic separation and degreasing treatment; the waste wood fiber comes from waste wooden templates, straw, or rice husks, and its particle size is controlled between 0.1 and 1 mm.

3. The all-solid waste-based water treatment material according to claim 1, characterized in that, The material is spherical particles with a diameter of 5-8 mm and longitudinal and transverse grooves with a depth of 1-2 mm on its surface.

4. The all-solid-waste-based water treatment material according to claim 1, characterized in that, The material has a closed-cell structure formed by the gas generated from the decomposition of waste wood fiber and the reduction of iron oxide in steel slag being enveloped by a high-temperature liquid phase; and zero-valent iron particles and carbon particles are covered and fixed by a silicate network skeleton formed by solidification, forming a micro-electrolysis unit inside the material.

5. The all-solid waste-based water treatment material according to claim 4, characterized in that, The silicate network framework is derived from the eutectic material formed at high temperatures by calcium silicate minerals in steel slag, waste glass, and engineering slurry.

6. The all-solid waste-based water treatment material according to claim 1, characterized in that, In step S2, the waste wood fiber is added in two stages: 50% is fed into the ball mill along with other raw materials for grinding, and the remaining 50% is added in the mixing stage of step S3.

7. The all-solid waste-based water treatment material according to claim 1, characterized in that, The strength of the green blank obtained by pressing in step S3 is sufficient to prevent it from breaking when dropped freely from a height of 1 meter.

8. The all-solid waste-based water treatment material according to claim 1, characterized in that, The roasting process in step S4 utilizes the residual heat of steel slag from the steel plant as a heat source.

9. The application of a solid waste-based water treatment material according to any one of claims 1-8 in wastewater treatment, characterized in that, The material was subjected to targeted inoculation with polyphosphate-accumulating bacteria to construct an iron-carbon-biofilm coupled phosphorus removal system for deep phosphorus removal.