153 results about "Zerovalent iron" patented technology

The invention belongs to the technical field of wastewater treatment, and particularly relates to a composite material as well as a preparation method and application thereof. According to the composite material, blended hydrogel of sodium alginate and polyvinyl alcohol is used as a matrix, zeolite molecular sieves, activated charcoal and zero-valent iron particles are embedded into the matrix to form microspheres, sulfate reducing bacteria are immobilized on the surfaces of the microspheres, the composite material is directly added into a mine water anaerobic reactor, the sulfate radical removal rate exceeds 92%, and the sulfate radical removal rate exceeds 92%. Heavy metals such as Cu, Pb and Cr in the mine water can be synchronously precipitated, and the treatment efficiency and stability of the anaerobic system are remarkably improved.

The invention relates to the technical field of wastewater treatment and resource recovery, and discloses an organophosphorus degradation and recovery system based on double-cathode electro-Fenton reaction, comprising: an electrolytic tank for accommodating organophosphorus wastewater to be treated; the anode is arranged in the electrolytic tank and is electrically connected with an anode of a power supply; the oxidizing agent generating cathode is arranged in the electrolytic tank and is used for generating hydrogen peroxide in situ under a power-on condition; the metal reduction cathode is arranged in the electrolytic tank and is used for adsorbing and reducing ferric ions; the metal source is composed of zero-valent iron or iron alloy, is not directly and electrically connected with the power source, and is arranged in an electric field acting area established by the anode and the at least one cathode. Through the design of inductive slow-release iron supply and double-cathode collaborative circulation, a series of problems of uncontrollable iron ion release, high iron sludge yield, low catalyst utilization efficiency, difficulty in resource recovery and the like in the traditional electro-Fenton technology are effectively solved.

According to the red mud-based composite material and the preparation method and application thereof, bentonite, red mud and biomass are mixed in a proper amount of water according to the mass ratio of 1: 1: (1-10), and first suspension liquid is formed; drying the first suspension to obtain a precursor of the red mud-based composite material; the precursor is subjected to a carbon thermal reaction at 300-700 DEG C, ferric oxide in the red mud is converted into zero-valent iron, and the red mud-based composite material is obtained. The red mud is alkaline and promotes manganese ions to form insoluble precipitates, the unique structure and ion exchange capacity of the bentonite can effectively solidify the manganese ions, the biomass has a high specific surface area and a developed pore structure, and the manganese ions are physically adsorbed through Van der Waals' force and pore interception; ferric oxide in the red mud is converted into zero-valent iron in the carbothermal reaction process, and the zero-valent iron can catalytically oxidize ammonia nitrogen, so that the red mud-based composite material synchronously solves the problem of combined pollution of manganese and ammonia nitrogen in the soil.

The invention discloses a preparation method and application of modified zero-valent iron based on wet ball milling, and the preparation method is characterized by comprising the following steps: pre-mixing commercially available zero-valent iron powder and a transition metal salt solution, introducing into a crowbar type high-energy ball mill for ball milling, and eluting an aqueous solution to obtain the modified zero-valent iron. The transition metal salt is a salt in which a transition metal is a main metal component, such as a Co salt, an Ni salt, or a Cu salt. The concentration in the solution is 0.01-1.00 mol / L according to the amount of substance concentration, and the concentration of the zero-valent iron in the solution is 1-500 g / L according to the solid-to-liquid ratio. The obtained wet ball-milling modified zero-valent iron can be applied to removal of (similar) metal pollutants in industrial wastewater. The prepared zero-valent iron has high reaction activity, compared with traditional zero-valent iron, the rate of removing metal and metalloid pollutants in industrial wastewater can be increased by 30-600 times, and the zero-valent iron has the advantages of being easy and convenient to operate, capable of achieving large-scale production, low in pollutant treatment cost and the like.

The invention discloses a submicron sphere soil remediation material as well as a preparation method and application thereof. The remediation material takes modified silicon dioxide as an inner core, nano zero-valent iron as a middle layer and aluminum oxide as an outer layer; the mass ratio of the inner core to the middle layer to the outer layer is (30-50): (20-40): (10-50). The remediation material synthesized through the method has the advantages of being good in soil compatibility, high in cyclic utilization rate, high in heavy metal removal efficiency and the like, and the target of low-energy-consumption remediation of the heavy metal contaminated soil can be achieved.

The invention discloses an iron-carbon composite material for heavy metal contaminated soil remediation and a preparation method of the iron-carbon composite material, and belongs to the field of heavy metal contaminated soil remediation. The iron-carbon composite material comprises rape straw, hydroxyapatite, zero-valent iron, sulfydryl functionalized magnetic cerium oxide and nitrogen-doped graphene quantum dot-sodium alginate. The sulfydryl-functionalized magnetic cerium oxide is prepared from cerium nitrate and ferric nitrate through precipitation, calcination and sulfhydrylation, and the nitrogen-doped graphene quantum dot-sodium alginate is prepared from citric acid and urea through microwave reaction, dialysis, mixing and freeze drying; the preparation method comprises the following steps: treating straws and hydroxyapatite to obtain ball-milled phosphorus-containing biochar, mixing the ball-milled phosphorus-containing biochar with zero-valent iron and two modifiers, and carrying out molding and high-temperature calcination to obtain the phosphorus-containing biochar-based composite material. The material has a remarkable remediation effect on the heavy metal contaminated soil, can effectively reduce the activity of heavy metals in the soil, has the characteristics of environmental friendliness and high stability, and is suitable for treating the soil compositely contaminated by the heavy metals such as cadmium and lead.

The invention discloses a thickening suspending agent containing modified attapulgite and application of the thickening suspending agent, and belongs to the technical field of thickening suspending agents. After acidification treatment, the content of impurities on the surface of attapulgite is reduced, the surface area and the porous property are increased, the load rate of zero-valent iron can be increased, and the utilization rate of the zero-valent iron is increased. Zero-valent iron is uniformly loaded on tubular pore channels or the surface of attapulgite in the form of nano-particles, so that the surface roughness of the composite powder is increased, stronger steric hindrance can be formed around pesticide particles, and the pesticide particles are prevented from being gathered and enlarged due to collision, so that sedimentation is reduced, and the composite powder has good suspension property and dispersity; the load of zero-valent iron can endow the thickening suspending agent with the heavy metal chelating capability; through two times of intercalation treatment, the modified zero-valent iron composite attapulgite powder can be uniformly loaded between graphene oxide layers, the graphene oxide can assist the dispersion of the attapulgite to avoid agglomeration, and the existence of the graphene oxide can improve the thermal stability of the thickening suspending agent.

The invention belongs to the technical field of underground water pollution remediation functional catalytic materials and water treatment, and particularly relates to a modified iron heterojunction biomass slow-release material, a preparation method thereof and application of a coupled electric field in underground water organic pollutant remediation. The mushroom biochar is used as a carrier to load the modified zero-valent iron, so that the problem of iron agglomeration is effectively relieved; and the modified zero-valent iron grows in the three-dimensional pore channel of the charcoal in situ, so that the slow release of the iron active component can be realized, and the utilization efficiency of the oxidizing agent is improved. An electric field is built in the iron-carbon structure reinforcing material, so that the problem of slow mass transfer in an underground water medium is solved, and the surface accessibility of an oxidizing agent and pollutants is improved. The material not only can reduce the invalid consumption of an oxidizing agent caused by overhigh local Fe < 2 + > concentration, but also can drive directional electron migration through an electric field, realizes space-time matching and dynamic regulation and control of an electron transfer rate and an iron supply rate, forms an in-situ regeneration closed-loop system, and has a good application prospect in groundwater remediation.

This invention discloses a method for the simultaneous preparation of micronized and stabilized zero-valent iron (ZVFe) based on ball milling with terephthalic acid, belonging to the field of groundwater pollution remediation materials. The method includes the following steps: 1) incorporating terephthalic acid into micron-sized ZVFe powder and mechanically ball milling it; 2) cleaning the material with a solvent and drying it to obtain micronized and stabilized ZVFe reducing material. This invention simultaneously achieves the micronization and stabilization of ZVFe. This method enhances the reducing activity, internal surface hydrophobicity, and electron selectivity of ZVFe materials, improves their reducing performance and electron selectivity for pollutants such as halogenated hydrocarbons and heavy metals, effectively inhibits the oxidative deactivation of ZVFe materials in the aquatic environment and the hydrogen evolution side reaction with water, enabling ZVFe materials to maintain high reducing activity stably in water for a long period. This invention solves the technical problems of poor stability and difficult storage of micronized ZVFe materials in water, which is beneficial for reducing material replacement frequency and resource consumption.

This invention relates to a modified zero-valent iron / biochar composite material with oxygen-rich vacancies and its application. The modified zero-valent iron / biochar composite material comprises a biochar carrier and zero-valent iron loaded on the biochar carrier. The surface of the zero-valent iron is coated with sulfur-containing iron compounds and / or boron-containing iron compounds, and the surface of the zero-valent iron contains abundant oxygen vacancies. The modified zero-valent iron / biochar composite material is specifically prepared by the following method: dispersing the biochar carrier and zero-valent iron in oxygen-free water and grinding; adding a sulfur source or boron source to the ground suspension, stirring and grinding thoroughly, and drying; subsequently soaking in a reducing solution, followed by high-temperature calcination and cooling to obtain the modified zero-valent iron / biochar composite material. Compared with the prior art, the modified zero-valent iron / biochar composite material prepared by this invention can be used synergistically with compound oxidants to achieve effective remediation of organically contaminated soil.

The utility model discloses a groundwater remediation module based on osmotic oxidation, which belongs to the technical field of environmental remediation and comprises a water-resisting layer, a remediation mechanism is slidably connected to the inner side of the water-resisting layer, and quick release mechanisms are arranged on two sides of the water-resisting layer. The remediation mechanism can be conveniently and independently replaced when the reaction medium zero-valent iron, activated carbon particles and limestone are subjected to performance reduction, failure and the like due to long-time use, the whole remediation module does not need to be disassembled on a large scale, the maintenance cost and difficulty are effectively reduced, continuous and efficient development of underground water remediation work is guaranteed, and the remediation efficiency is improved. When the repair mechanism needs to be integrally overhauled and replaced or parts such as an internal filtering frame need to be deeply maintained, the repair mechanism can be quickly detached from the water-resisting layer through the quick detaching mechanism, so that the time and the labor cost are greatly saved, and the maintainability and the use flexibility of the whole underground water repair module are improved.

The application discloses a Ce2S3@Fe composite material and a preparation method and application thereof, and belongs to the technical field of radioactive wastewater treatment, and the preparation of the Ce2S3@Fe composite material comprises the following steps: under the protection of inert gas, cerium sulfide is added into a ferric iron solution, and then a sodium borohydride solution is slowly added dropwise, so that the ferric iron is reduced to zero-valent iron by using the reducing property of the sodium borohydride solution and is uniformly loaded on the surface of the cerium sulfide, thereby forming the Ce2S3@Fe composite material; and the prepared Ce2S3@Fe composite material is applied to purification of uranium-containing wastewater. 2+ The application adopts the above Ce2S3@Fe composite material, the preparation method and the application thereof, and has the advantages of convenient operation, low cost, environmental friendliness, fast reduction rate, long UO2 stabilization time, all-weather operation, simultaneous consideration of radioactive wastewater treatment and uranium resource recovery.

The invention relates to preparation of graphene-loaded nano zero-valent iron and application of the graphene-loaded nano zero-valent iron in chromium-containing wastewater treatment. The preparation method comprises the following steps: preparing 60mL of a KBH4 solution with the concentration of 0.5 mol / L as a solution A and 60mL of a FeSO4. 7H2O solution with the concentration of 0.1 mol / L as a solution B, adding 0.25 g of a single-layer graphene oxide dispersion liquid into the solution B, stirring for 30 minutes, recording as a solution C, slowly dripping the solution A into the solution C, performing suction filtration separation on powder C, and drying to obtain nZVI-coated GO. The graphene is loaded with nZVI to adsorb chromium in chromium-containing wastewater, and nZVI-GO-Cr formed after wastewater treatment can be used as an auxiliary tanning agent for leather tanning or retanning sections and has good recyclability.

The application discloses a nano zero-valent iron modified hemicellulose biochar composite material and a preparation method and application thereof. The preparation method comprises the following steps: mixing xylan raw materials and iron oxide, performing ball milling treatment, and then performing a carbothermic reduction process in a microwave pyrolysis device under a nitrogen protection atmosphere and a constant temperature condition, so as to obtain the nano zero-valent iron modified hemicellulose biochar material after cooling. The composite material is prepared by using the above preparation method. The composite material is applied to purification treatment of polluted wastewater containing chlorinated hydrocarbons. The composite material has low raw material cost, simple preparation method, can form stable structure pores, has good adsorption performance and catalytic activity, realizes molecular dispersion of zero-valent iron in a hemicellulose biochar matrix, and improves adsorption and reduction capacity of the composite material on chlorinated hydrocarbon pollutants.

The application provides a phosphorus modified zero-valent iron catalytic material, a preparation method, a remediation agent and application. 3‑ The phosphorus modified zero-valent iron catalytic material is obtained, wherein the particle size of the zero-valent iron is micron level. The preparation method of the application can be completed in an air atmosphere, and does not need high temperature, vacuum or addition of toxic chemical reagents. The preparation process only involves physical mixing and mechanical ball milling, the equipment requirement is simple, the operation is convenient, the energy consumption is low, the dual benefits of environmental governance and ecological restoration are combined, and the green and sustainable development environmental governance concept is met.

The invention discloses a nano zero-valent iron composite sponge filler, a preparation method thereof and a nitrate sewage denitrification method, and relates to the technical field of sewage treatment materials. Polyurethane sponge is used as a matrix, and the nanoscale zero-valent iron composite sponge filler is prepared through the steps of dipping of a PVA-PQ-10 / waterborne polyurethane modified adhesive, crosslinking of a FeCl3 solution, reduction of a NaBH4 solution and the like in sequence. The modified adhesive is utilized to endow the surface of the carrier with positive electricity and hydrophilicity, so that the biocompatibility of the carrier is remarkably enhanced; and nano zero-valent iron is stably loaded in the three-dimensional network structure of the sponge through an in-situ reduction method. The nano zero-valent iron composite sponge filler prepared by the invention has high reaction activity, excellent denitrification effect and good sludge granulation capability, and is suitable for sewage treatment.

The invention discloses a preparation method and application of gradient core-shell zero-valent iron porous ceramsite, and belongs to the technical field of solid waste recycling and water pollution control. According to the invention, steel slag, red mud, fly ash and municipal sludge are taken as main raw materials, and free heavy metals are removed in a targeted manner through composite acid leaching and Fe-Mn modified charcoal adsorption pretreatment; through in-situ curing of a composite curing agent, pre-sintering and three-section type high-temperature sintering, heavy metal is stably dissolved in ceramsite lattices in a solid mode, secondary pollution caused by leaching of heavy metal ions is avoided, a gradient shell structure with a TiO2 inner layer / biochar-fly ash outer layer is constructed, SiO2 coating modification is conducted on zero-valent iron, and a double-barrier and activity protection mechanism is formed. The prepared gradient core-shell zero-valent iron porous ceramsite shows excellent deep purification capacity in arsenic-containing wastewater treatment, safe recycling of multi-source solid waste and efficient deep purification of high-concentration arsenic-containing wastewater are synchronously achieved, and the gradient core-shell zero-valent iron porous ceramsite has remarkable environmental and economic benefits.

The application discloses a preparation method of zero-valent iron with a high Fe(II) content magnetite interface by regulating the redox intensity, and belongs to the field of water treatment. The method comprises the following steps: uniformly mixing zero-valent iron particles and ferrous ion solution at 20 DEG C-30 DEG C, regulating the initial pH value to 1-4 by using a sulfuric acid solution, adding a sulfur ion solution after 20 min of reaction and reacting for another 5 min, wherein the mass ratio of the added sulfur ion to the initial ferrous ion is 0.2-0.4:1; after the reaction is completed, the zero-valent iron particles are separated by magnetism, and are dried in a vacuum oven at 40 DEG C-60 DEG C for 4-12 h to obtain Fe3O4@mZVI materials. The zero-valent iron composite material with a high Fe(II) content magnetite interface prepared by the method can be prepared in an open system without controlling the anaerobic reaction atmosphere environment. Meanwhile, the ferrous ion is oxidized by using air, and no external oxidizing agent is needed, so that the method has the advantages of simple and rapid preparation and low cost. In the preparation process, the sulfur ion is added to regulate the redox reaction degree, the proportion of Fe(II) on the material surface is significantly improved, and the zero-valent iron composite material has better reaction activity and durability for pollutant removal.

The application discloses low-cost sulfidized nano zero-valent iron synthesized by using pyrite as raw material and application thereof. The low-cost sulfidized nano zero-valent iron is obtained by using cheap pyrite powder as raw material, adding a small amount of anhydrous FeCl3, and through ball milling, drying and hydrogen reduction. The pyrite powder to which a small amount of anhydrous FeCl3 is added is ball milled by using zirconia ball milling beads which are easy to clean but not easy to be polluted, and then the sulfidized nano zero-valent iron is prepared after drying and reduction. By adjusting parameters such as ball powder ratio, FeCl3 addition amount, heating rate and holding time, the low-cost sulfidized nano zero-valent iron with a particle size of 200-300 nm, zero-valent iron content accounting for more than 90% of total iron content and preparation cost being 11% of that of a laboratory liquid-phase synthesis method is prepared. The material can effectively degrade trichloroethylene (TCE) and florfenicol (FF), has a small hydrogen production amount and a high electron efficiency. The preparation method is simple and easy to operate, has a low cost and has a large-scale production prospect, the degradation performance of pollutants is close to that of the laboratory-prepared sulfidized nano zero-valent iron, and far exceeds that of nano zero-valent iron, and therefore the material has a prospect of being applied to actual groundwater pollution remediation.

The application provides a groundwater in-situ remediation system and method of multiple biological permeation reaction wall coupling ultrasonic waves and plant remediation, the groundwater in-situ remediation system comprises a multiple biological permeation reaction wall, a PLC control system and an artificial plant ecological remediation area, the multiple biological permeation reaction wall is arranged in a funnel-gate type engineering, the funnel part blocks the contaminated groundwater through a vertical cement curtain, an ultrasonic generator module is arranged in front of the gate part of the multiple biological permeation reaction wall, the multiple biological permeation reaction wall is divided into two layers, the filling material of the first layer permeation reaction wall is mainly composed of zero-valent iron, iron oxide and construction waste, the filling material of the second layer biological permeation reaction wall is mainly composed of high-performance biological adsorption zeolite and ORC slow-release material calcium peroxide, a microbial bacteria liquid injection pipe is arranged in the second layer biological permeation reaction wall, and monitoring wells are arranged on the two sides of the multiple biological permeation reaction wall and the artificial plant ecological remediation area.The application can treat and remediate multiple composite pollutants at a time, and the pollutant degradation efficiency is improved.

The application belongs to the technical field of water treatment, and particularly relates to a groundwater heavy metal removal system and method, wherein a water solution of a complexing agent is injected into groundwater at an upstream, the complexing agent comprising the following components in parts by weight: 10 parts of ethylenediamine disuccinic acid tetrasodium salt; 3-3.5 parts of sodium gluconate; 1.5-2 parts of ferrous sulfate heptahydrate; 0.8-1 part of citric acid monohydrate; and 5-6 parts of sodium bicarbonate; a reaction wall is built at a downstream, a strong reduction filler layer is arranged in the reaction wall, the strong reduction filler layer comprises sulfur-modified zero-valent iron particles and conductive particles, the strong reduction filler layer reduces high-valence heavy metals in the groundwater to generate stable precipitates, and the application can promote the heavy metals to flow to the reaction wall, avoid the heavy metals from being retained in soil, and improve the removal effect on the heavy metals.

The utility model belongs to industrial wastewater treatment technical field discloses a kind of Fenton oxidation pond packing shelf and Fenton reaction pond device, including packing shelf body and at least two hanging material layers, and packing shelf body includes upper shelf body and lower shelf body, and both are detachably connected along vertical direction, and upper shelf body top is provided with lifting connection structure;At least two hanging material layers are respectively arranged on upper shelf body and lower shelf body, and each layer hanging material layer includes multiple hanging material cross beams that are arranged in parallel along horizontal interval, and multiple filter bags are detachably and interval hung along the length direction of each hanging material cross beam, and filter bag interior is filled with zero-valent iron reagent, and raw water in oxidation pond can contact reaction with zero-valent iron reagent in its interior through the small hole of filter bag.The utility model effectively improves the contact efficiency of reaction reagent, reduces ferrous sulfate consumption, makes reaction process more sufficient, accelerates reaction rate, improves treatment effect;Meanwhile, it is convenient to quickly replace and supplement reaction reagent on packing shelf, and operation is simple.

The invention belongs to the technical field of environmental functional materials and soil remediation, and particularly relates to a micron-sized zero-valent iron nitride catalyst as well as a preparation method and application thereof. The invention provides a nitrided micron zero-valent iron catalyst which is prepared by doping micron-sized iron powder with urea, the nitrogen content of the catalyst is 0.5 wt%-4.5 wt%, and the particle size of the micron-sized iron powder is 10-300 microns. The preparation method comprises the following steps: putting raw materials urea and micron-sized iron powder into a ball milling tank, adding grinding balls, and carrying out ball milling for 2-10 hours at the rotating speed of 450-550rpm in an air atmosphere; and drying the product after ball milling is finished, thereby obtaining the product. The catalyst is not only suitable for efficient deep treatment of high-concentration organic contaminated leacheate, but also can be directly used for chemical oxidation remediation of contaminated soil, and has remarkable engineering application value.

The invention discloses an autotrophic denitrification filler as well as a preparation method and application thereof, and relates to the technical field of water treatment. The autotrophic denitrification filler is prepared from the following raw materials in parts by mass: 64 parts of sulfur powder, 25 parts of oyster shells, 10 parts of iron powder and 1 part of a foaming agent. When the autotrophic denitrification filler is used, sulfur / iron autotrophic denitrification bacteria on the surface of the filler take elemental sulfur and zero-valent iron as electron donors, oyster shells slowly release CaCO3 to provide alkalinity and an inorganic carbon source, and NO3 <->-N is reduced into N2; meanwhile, the dissolved-out Fe < 2 + > and PO4 < 3-> in the water body are subjected to precipitation, Fe3 (PO4) 2 insoluble precipitates are formed, and synchronous phosphorus removal is achieved. The autotrophic denitrification filler disclosed by the invention has relatively high hardness and compressive strength, relatively low density and relatively long service life. The autotrophic denitrification filler disclosed by the invention has the advantages of cheap and easily available raw materials, simple preparation process and no need of additional carbon sources during use, and is suitable for high-efficiency, low-cost and low-carbon emission treatment of low-carbon-nitrogen-ratio aquaculture tail water.

The invention belongs to the technical field of catalysts, and discloses a C2N coated sulfurized zero-valent iron catalyst and a preparation method and application thereof. The catalyst comprises C2N and sulfurized zero-valent iron, and the C2N wraps the surface of the sulfurized zero-valent iron. The method has the advantages that (1) the surface of the sulfurized zero-valent iron is coated with a layer of two-dimensional material C2N, electrons in the zero-valent iron are accelerated to flow to the surface and are in better contact with an oxidant PDS, so that the activation efficiency of persulfate is greatly improved, and chlorinated organic pollutants in underground water are efficiently removed; through the vapor deposition process of C2N precursor pyrolysis, a uniform and ultrathin C2N layer can be formed on the surface of S-ZVI, strong chemical bonding is formed between C2N and the surface of S-ZVI, and an efficient electron conduction channel is constructed. The structural design is beneficial to accelerating migration of electrons in the S-ZVI to the surface, and the activation efficiency of PDS is improved.

The invention relates to a biochar-loaded nano zero-valent iron repair material as well as a preparation method and application thereof. The biochar loaded nano zero-valent iron repair material is prepared from a persulfate-biochar carrier and metal sulfide modified composite acid stabilized nano zero-valent iron sol, the composite acid is composed of gallic acid and humic acid / fulvic acid; the preparation method comprises the following steps: S1, preparing a persulfate-biochar carrier; and S2, preparing the biochar loaded nano zero-valent iron repair material. The method is applied to groundwater chlorohydrocarbon pollution remediation. According to the method, in the reductive dechlorination process of the nano zero-valent reduced iron, released Fe < 2 + > can strengthen persulfate, Fe < 2 + > is regenerated by utilizing the reduction effect of gallic acid on reacted Fe < 3 + >, and catalytic circulation of iron is maintained; humic acid / fulvic acid is used for efficiently driving the degradation process; and metal sulfide is utilized to catalyze reduction of organic chlorine chemicals, so that the reductive dechlorination performance of the nano-iron material is improved, and the repairing effect of chlorinated hydrocarbon is optimized.

The invention discloses a method for independently recovering phosphate and nano zero-valent iron through anaerobic fermentation of excess sludge. The method comprises the following steps: adding the excess sludge into an anaerobic reactor, electrifying a cathode plate and an anode plate in the anaerobic reactor, keeping for a period of time, carrying out anaerobic fermentation on anaerobic microorganisms in the excess sludge, enabling phosphorus elements in the excess sludge to enter supernate, reducing the iron element in the residual sludge on the cathode plate to generate nanoscale zero-valent iron, and separating the supernate from the cathode plate after electrifying is finished; the electrifying condition is as follows: the control voltage is 1.5-5.0 V. According to the method disclosed by the invention, the release of phosphate in the supernate and the electrochemical reduction of Fe on a cathode plate can be realized to generate the nano zero-valent iron. Meanwhile, the anaerobic fermentation process is not affected in the electrifying stage, and the ratio of acetic acid in volatile acid is increased.

The invention discloses a method for recovering valuable metals through zero-valent iron-bacteria synergistic reduction of minerals, and belongs to the field of biological metallurgy. The method comprises the following steps: crushing and grinding natural cobalt-containing magalite, fully mixing with a background solution with the pH value of 7.3, zero-valent iron chips and dissimilatory metal reducing bacteria cells under an anaerobic condition, and carrying out shake culture in a constant-temperature shaking table at the temperature of 30 DEG C and the speed of 150 rpm in a dark place. The zero-valent scrap iron can be used as a long-term and stable electron donor, and the zero-valent scrap iron and bacteria are used for reducing cobalt-containing doloxymanganese ore together. According to the method, the zero-valent scrap iron and the dissimilatory metal reducing bacteria are cooperatively used, reduction of the cobalt-containing medoxymanganese ore can be effectively promoted, Co < 2 + > is efficiently released, the performance is superior to the condition of separately adding the zero-valent scrap iron and the bacteria, and the promotion effect is remarkable. The zero-valent scrap iron is long-acting, stable, green, environment-friendly and free of pollution by-products, and is expected to be popularized and applied in practice.

The application belongs to the technical field of wastewater treatment, and particularly relates to a composite material and a preparation method and application thereof. The composite material takes a blended hydrogel of sodium alginate and polyvinyl alcohol as a matrix, zeolite molecular sieves, activated biochar and zero-valent iron particles are embedded in the matrix to form microspheres, and sulfate-reducing bacteria are immobilized on the surface of the microspheres. The composite material is directly added into an anaerobic reactor of mine water, the removal rate of sulfate is more than 92%, and heavy metals such as Cu, Pb and Cr in the mine water can be simultaneously precipitated, and the treatment efficiency and stability of the anaerobic system are significantly improved.