Microbial solidified biochar material and heavy metal sewage treatment method thereof

Abstract

The invention provides a microorganism curing biochar material and a heavy metal sewage treatment method thereof. The microorganism curing biochar material comprises modified biochar, functional microorganisms, an intelligent responsive polymer coating and quantum dots. The high-performance material is prepared through acid treatment, loading of metal oxide modified biochar, compounding with specific functional microorganisms, coating of an intelligent responsive polymer coating and bonding of quantum dots, when heavy metal sewage is treated, all the components have a synergistic effect, the adsorption and conversion capacity is improved, the environmental adaptability is enhanced, real-time monitoring is achieved, and the application prospect is wide. The sewage treatment efficiency and quality are effectively improved; pretreatment is set in the sewage treatment process, and the addition proportion, the reaction temperature, the stirring rotating speed, the reaction time and the like of a microorganism solidified biochar material are reasonably controlled, so that the high removal rate of various heavy metal ions is realized; meanwhile, the microorganism solidified biochar material can be repeatedly used, so that the use of a large number of chemical agents is avoided, the secondary pollution is reduced, and remarkable economic and environmental benefits are brought.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a microbial solidified biochar material and a heavy metal sewage treatment method thereof. Background Art

[0002] With the rapid development of industry, heavy metal pollution has become a serious problem facing the water environment. Heavy metals are difficult to degrade in water and can be enriched through the food chain, posing a great threat to human health and the ecological environment. Traditional heavy metal wastewater treatment methods, such as chemical precipitation and ion exchange, have problems such as high cost and easy secondary pollution. Biochar, as a new adsorption material, has a large specific surface area and rich pore structure, and has a certain adsorption capacity for heavy metals.

[0003] However, the functional groups on the surface of biochar are limited, and the removal effect of heavy metals when used alone needs to be improved; at the same time, microorganisms have unique advantages in heavy metal wastewater treatment, and can reduce the toxicity of heavy metals through adsorption and conversion, but microorganisms are easily lost in water bodies and are difficult to reuse;

[0004] Therefore, a microbial solidification biochar material and a heavy metal wastewater treatment method thereof are proposed. Summary of the invention

[0005] In view of this, the embodiments of the present invention hope to provide a microbial solidification biochar material and a heavy metal wastewater treatment method thereof to solve or alleviate the technical problems existing in the prior art and at least provide a beneficial option.

[0006] To solve the above technical problems, a technical solution adopted in the present application is: a microbial solidification biochar material, including modified biochar, functional microorganisms, smart responsive polymer coating and quantum dots;

[0007] The modified biochar is obtained by first subjecting the biochar to acid treatment, introducing carboxyl groups and hydroxyl groups on its surface, and then subjecting it to metal oxide loading treatment; the functional microorganisms are screened, and strains with tolerance to heavy metals and adsorption and conversion capabilities are selected, mixed with an embedding agent and solidified by a freeze-crosslinking method to form adsorption-embedded composite fixed microbial particles, which are then composited with the modified biochar; the intelligent responsive polymer coating is coated on the surface of the composite modified biochar, and is composited with a thermosensitive polymer N-isopropylacrylamide and a pH-sensitive polymer polyacrylic acid; the quantum dots are connected to the surface of the modified biochar by chemical bonding.

[0008] As a further preferred embodiment of the present technical solution, the acid treatment uses a hydrochloric acid solution with a concentration of 1-3 mol / L, and the reaction is stirred at 80-100° C. for 2-4 hours.

[0009] As a further preferred embodiment of the present technical solution, during the loaded metal oxide treatment, the metal salt solution used to soak the biochar is a solution of one of ferric nitrate and manganese nitrate or a mixture of the two in proportion, the metal salt concentration is 0.1-0.3 mol / L, the soaking time is 12-24 hours, the calcination temperature is 300-500°C, and the calcination time is 2-3 hours.

[0010] As a further preferred embodiment of the present technical solution, the functional microorganism is one or more of Bacillus and Pseudomonas; the quantum dots are cadmium sulfide quantum dots; and the embedding agent is a mixture of sodium alginate and calcium chloride in a certain proportion.

[0011] In order to solve the above technical problems, another technical solution adopted in this application is: a method for treating heavy metal wastewater by using microbial solidification of biochar materials, comprising the following steps:

[0012] Step 1: collecting heavy metal wastewater and pre-treating the collected heavy metal wastewater;

[0013] Step 2: adding the microbial solidified biochar material into the reaction container in proportion according to the concentration of heavy metal ions in the heavy metal wastewater;

[0014] Step 3: inject the pretreated heavy metal wastewater into the reaction vessel containing the microbial solidified biochar material, and stir the reaction for 3-8 hours at a temperature of 20-35° C. and a stirring speed of 100-200 r / min;

[0015] Step 4: After the reaction is completed, the treated microbial solidified biochar material is separated from the heavy metal wastewater by a combination of filtration and centrifugation;

[0016] Step 5: Detect the heavy metal content of the separated heavy metal wastewater. If the concentration reaches the discharge standard, it will be discharged or reused; if the concentration does not reach the discharge standard, repeat the above treatment steps.

[0017] As a further preferred embodiment of the present technical solution, in step one, the pretreatment of the collected heavy metal wastewater includes filtration treatment and pH adjustment treatment, the filtration treatment is performed through a filter with a pore size of 0.2-0.5 μm, and the pH adjustment treatment uses sodium hydroxide or hydrochloric acid solution to adjust the pH value of the filtered heavy metal wastewater to between 6 and 8.

[0018] As a further preferred embodiment of the present technical solution, in step 2, the microbial solidified biochar material is added into the reaction container in proportion, and the addition is performed at a ratio of 0.1-0.5 g of microbial solidified biochar material per liter of heavy metal wastewater.

[0019] As a further preferred embodiment of the present technical solution, in step 4, the method of combining the filtration and the centrifugal treatment is as follows:

[0020] First filter through a filter membrane with a filtration accuracy of 0.1-0.3μm, and then centrifuge at a speed of 3000-5000r / min for 5-10 minutes.

[0021] As a further preferred embodiment of the present technical solution, in step five, the heavy metal content of the separated heavy metal wastewater is detected, and the concentration of heavy metal ions in the heavy metal wastewater is determined by atomic absorption spectroscopy.

[0022] As a further preferred embodiment of the present technical solution, in step three, a temperature control system is provided in the reaction container, and the reaction temperature is controlled within a range of ±2°C of the set temperature by a heating or cooling device.

[0023] The embodiment of the present invention has the following advantages due to the adoption of the above technical solution:

[0024] 1. The present invention prepares high-performance materials by acid treatment and loading metal oxides to modify biochar, compound with specific functional microorganisms, coat with intelligent responsive polymer coating and bond with quantum dots. When treating heavy metal wastewater, the various components work synergistically to improve adsorption and conversion capacity, enhance environmental adaptability and achieve real-time monitoring, effectively improving wastewater treatment efficiency and quality;

[0025] 2. The present invention arranges pretreatment in the sewage treatment process to remove large particles of impurities and adjust the pH value, reasonably controls the addition ratio of microbial solidified biochar materials, reaction temperature, stirring speed and reaction time, and adopts a separation method combining filtration and centrifugation, atomic absorption spectrometry detection and temperature control system to achieve a high removal rate of various heavy metal ions, so that the sewage can be discharged or reused in compliance with the standards; at the same time, the microbial solidified biochar materials are reusable, the treatment process is simple, the cost is reduced, and the use of a large amount of chemical agents is avoided, reducing secondary pollution, conforming to the concept of environmental protection, and bringing significant economic and environmental benefits.

[0026] The above summary is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments and features described above, further aspects, embodiments and features of the present invention will be readily apparent by reference to the accompanying drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of the process of treating heavy metal wastewater using microbial solidification of biochar materials according to the present invention. DETAILED DESCRIPTION

[0029] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0030] It should be clear that the following embodiments of the present disclosure are described by specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other in the absence of conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0031] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0032] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure. The drawings only show components related to the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0033] Additionally, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, it will be understood by those skilled in the art that the aspects described may be practiced without these specific details.

[0034] Embodiment 1

[0035] The embodiment of the present invention provides a microbial solidification biochar material, including modified biochar, functional microorganisms, smart responsive polymer coating and quantum dots;

[0036] The modified biochar is obtained by first subjecting the biochar to an acid treatment, introducing carboxyl groups and hydroxyl groups on its surface, and then subjecting it to a metal oxide loading treatment; the functional microorganisms are screened, and strains with tolerance to heavy metals and adsorption and conversion capabilities are selected, mixed with an embedding agent, and solidified by a freezing-crosslinking method to form adsorption-embedded composite fixed microbial particles, which are then composited with the modified biochar; the intelligent responsive polymer coating is coated on the surface of the composite modified biochar, and is composited by a thermosensitive polymer N-isopropylacrylamide and a pH-sensitive polymer polyacrylic acid; the quantum dots are connected to the surface of the modified biochar by chemical bonding;

[0037] Among them, biochar itself has a certain adsorption capacity for heavy metals, but the surface functional groups are limited. Through acid treatment, using 1-3 mol / L hydrochloric acid solution to stir and react at 80-100°C for 2-4 hours, carboxyl and hydroxyl groups can be introduced on its surface. These acidic functional groups can enhance the ion exchange and complexing ability of biochar for heavy metals and improve the adsorption effect of heavy metals. After that, metal oxide loading treatment is carried out. The biochar is immersed in 0.1-0.3 mol / L of one of iron nitrate and manganese nitrate or a mixed solution of the two for 12-24 hours, and then calcined at 300-500°C for 2-3 hours to load metal oxides on the surface of the biochar, further improving its adsorption capacity and selectivity for heavy metals.

[0038] Functional microorganisms are strains that are tolerant to, adsorb and transform heavy metals, such as Bacillus and Pseudomonas, selected from environmental samples (such as soil or water contaminated by heavy metals). These strains are mixed with an embedding agent (sodium alginate and calcium chloride mixed in proportion) and solidified by freezing-crosslinking method. They are first frozen at low temperature (such as -10°C to -15°C), and then crosslinked and solidified for a certain period of time (3-4 hours) under certain conditions (such as 4°C) to form adsorption-embedding composite fixed microbial particles. This immobilization method can prevent the loss of microorganisms in the water body, so that they can stably compound with modified biochar and continue to play the role of adsorption and transformation of heavy metals.

[0039] The intelligent responsive polymer coating is a composite of a temperature-sensitive polymer N-isopropylacrylamide and a pH-sensitive polymer polyacrylic acid, and is coated on the surface of the composite microbial solidified biochar material. When the sewage temperature or pH value changes, the properties of the coating will change accordingly; for example, when the temperature rises or the pH value changes, the pore size of the coating will increase or decrease, and the surface properties will also change, thereby adjusting the exchange rate between the material and external substances, ensuring the activity of microorganisms, and improving the material's treatment performance for heavy metal sewage under different environmental conditions;

[0040] The quantum dots are cadmium sulfide quantum dots, which are connected to the surface of modified biochar through chemical bonding. The quantum dots not only increase the adsorption sites of biochar and improve the adsorption capacity of heavy metal ions, but also have unique optical properties and can be used as fluorescent probes. During the sewage treatment process, the concentration changes of heavy metal ions in the sewage can be monitored in real time. By detecting the changes in the fluorescence intensity of quantum dots, the sewage treatment process can be grasped in time to achieve precise treatment.

[0041] In one embodiment, specifically, the acid treatment uses a hydrochloric acid solution with a concentration of 1-3 mol / L, and reacts at 80-100° C. with stirring for 2-4 hours;

[0042] Among them, the use of a hydrochloric acid concentration range of 1-3 mol / L is determined through research and practice. If the concentration is too low, such as less than 1 mol / L, it is impossible to fully introduce acidic functional groups such as carboxyl and hydroxyl groups on the surface of biochar. These functional groups are crucial for the subsequent enhancement of the ion exchange and complexing ability of biochar for heavy metals. Insufficient introduction of functional groups will lead to limited improvement in the adsorption performance of biochar for heavy metals; and when the concentration is too high, exceeding 3 mol / L, on the one hand, it will increase production costs, and on the other hand, it will excessively corrode biochar and destroy its original pore structure, which is also not conducive to the adsorption of heavy metals; for example, when the hydrochloric acid concentration is 0.5 mol / L, the adsorption of certain heavy metal ions by the treated biochar is significantly lower than that of the biochar treated at a concentration of 1-3 mol / L; when the hydrochloric acid concentration reaches 4 mol / L, the pore structure of the biochar is partially destroyed, the specific surface area is reduced, and its adsorption capacity is affected;

[0043] Among them, the reaction temperature of 80-100℃ can provide a suitable reaction environment for acid treatment; when the temperature is lower than 80℃, the reaction rate is slow, the reaction between acid and biochar is not sufficient, resulting in insufficient introduction of acidic functional groups; and when the temperature is higher than 100℃, not only additional heating equipment and energy consumption are required, but also hydrochloric acid volatilization will be triggered, resulting in unstable acid concentration, affecting the treatment effect, and even having an adverse effect on the structure of biochar;

[0044] Among them, the stirring reaction time of 2-4 hours is also the result of optimization. Stirring can make the hydrochloric acid solution fully contact with the biochar and ensure that the reaction is carried out evenly. If the reaction time is too short, such as less than 2 hours, the acid treatment is not thorough, and the functional groups on the surface of the biochar are not completely converted, which affects the adsorption effect of heavy metals. If the reaction time is too long, more than 4 hours, although the introduction amount of some functional groups will increase, it will also increase the production cycle and cost, and too long a reaction time will cause a certain degree of damage to the structure of the biochar. For example, when the reaction time is 1 hour, the biochar has a poor adsorption effect on heavy metals. When the reaction time is extended to 5 hours, part of the structure of the biochar begins to degrade, which reduces its adsorption performance for heavy metals.

[0045] In one embodiment, specifically, during the metal oxide loading treatment, the metal salt solution used to soak the biochar is a solution of one of ferric nitrate and manganese nitrate or a mixture of the two in proportion, the metal salt concentration is 0.1-0.3 mol / L, the soaking time is 12-24 hours, the calcination temperature is 300-500°C, and the calcination time is 2-3 hours;

[0046] Among them, the metal salt solution uses iron nitrate, manganese nitrate or a mixed solution of the two because iron oxide and manganese oxide have good adsorption and catalytic properties for heavy metals; iron oxide can react chemically with a variety of heavy metal ions to form stable complexes, thereby enhancing the adsorption effect; manganese oxide has a strong redox ability and can convert some heavy metal ions into forms that are easier to adsorb or precipitate; when treating lead-containing wastewater, the adsorption capacity of biochar loaded with iron oxide for lead ions is significantly increased; when treating mercury-containing wastewater, manganese oxide can oxidize some mercury ions into high-valent states, which are easier to be adsorbed and fixed by biochar; choosing a mixed solution of the two can combine the advantages of the two metal oxides, broaden the treatment range of different heavy metals, and improve the versatility of the material;

[0047] The metal salt concentration range of 0.1-0.3 mol / L is selected to ensure that an appropriate amount of metal oxides are loaded on the biochar surface; if the concentration is lower than 0.1 mol / L, the amount of metal oxides loaded is small and cannot fully play its role in improving adsorption capacity and selectivity; if the concentration is higher than 0.3 mol / L, the metal oxides will accumulate excessively on the biochar surface, blocking the pore structure of the biochar, reducing its specific surface area, and affecting the original adsorption performance of the biochar;

[0048] Among them, the soaking time of 12-24 hours can ensure that the metal salt fully penetrates into the interior of the biochar and interacts with the surface; if the soaking time is too short, the metal salt cannot be fully loaded on the biochar, affecting the subsequent performance improvement; if the soaking time is too long, it will not only increase the production cycle and cost, but also cause damage to the biochar structure; for example, when the soaking time is 8 hours, the amount of metal oxide loaded on the surface of the biochar is insufficient, and the adsorption effect of heavy metals is not good; after soaking for 30 hours, part of the structure of the biochar becomes loose, affecting its mechanical strength and adsorption performance;

[0049] Among them, a calcination temperature of 300-500℃ and a calcination time of 2-3 hours can convert metal salts into stable metal oxides and firmly load them on the surface of biochar; when the calcination temperature is lower than 300℃, the metal salts cannot be completely converted into oxides, affecting their effect on heavy metals; when the temperature is higher than 500℃, the structure of biochar will be destroyed and its adsorption performance will be reduced; when the calcination time is shorter than 2 hours, the formation of metal oxides will be insufficient; when it is longer than 3 hours, the structure of biochar will be further damaged; if it is calcined at 250℃, the metal salt conversion is incomplete and the ability to remove heavy metals is weak; when calcined at 600℃, the pore structure of biochar is severely damaged and the adsorption performance is greatly reduced.

[0050] In one embodiment, specifically, the functional microorganism is one or more of Bacillus and Pseudomonas; the quantum dots are cadmium sulfide quantum dots; the embedding agent is a mixture of sodium alginate and calcium chloride in proportion;

[0051] Among them, Bacillus and Pseudomonas are microorganisms with special properties. They are tolerant to heavy metals and can survive in sewage environments containing heavy metals. At the same time, they have the ability to adsorb and transform heavy metals. They can adsorb heavy metal ions in sewage to the cell surface through special structures or metabolic processes on the cell surface, or transform highly toxic heavy metal ions into low-toxic or even non-toxic forms. For example, Bacillus can secrete extracellular polymers to react with heavy metal ions to form complexes, thereby adsorbing heavy metals; Pseudomonas can use its own enzyme system to reduce some heavy metal ions such as mercury ions to metallic mercury, thereby reducing their toxicity. Selecting one or more such microorganisms can more specifically improve the material's ability to remove heavy metals according to the types and characteristics of heavy metals in sewage.

[0052] Among them, cadmium sulfide quantum dots play a key role in the material; on the one hand, it is connected to the surface of modified biochar through chemical bonding, which increases the adsorption sites of the material. Quantum dots have a large specific surface area and abundant surface active sites, which can adsorb heavy metal ions, thereby increasing the material's adsorption capacity for heavy metals; on the other hand, cadmium sulfide quantum dots have unique optical properties and can be used as fluorescent probes to monitor the concentration of heavy metal ions in sewage in real time. When heavy metal ions exist in the environment, the fluorescence intensity of the quantum dots will change. By detecting this change, the concentration changes of heavy metal ions in sewage can be timely understood, providing a basis for the precise control of the sewage treatment process;

[0053] Among them, the embedding agent formed by mixing sodium alginate and calcium chloride is used to fix functional microorganisms; sodium alginate is a hydrophilic polysaccharide. After contacting with calcium ions (provided by calcium chloride), a cross-linking reaction will occur to form a gel with a three-dimensional network structure. After the functional microorganisms are mixed with sodium alginate and then added dropwise to the calcium chloride solution, the microorganisms are wrapped inside the gel network to form adsorption-embedded composite fixed microbial particles. This embedding method can effectively prevent the loss of microorganisms in the water body, allowing the microorganisms to stably exist in the material and continue to play a role in the adsorption and conversion of heavy metals. At the same time, the network structure of the gel has certain pores, allowing heavy metal ions and nutrients in sewage to enter, ensuring the material exchange between the microorganisms and the external environment and maintaining the activity of the microorganisms.

[0054] Embodiment 2

[0055] Figure 1 1 is a schematic diagram of a method for treating heavy metal wastewater by using microbial solidification of biochar materials according to an embodiment of the present invention. It should be noted that if there are substantially the same results, the method of the present application is not limited to Figure 1 The process sequence shown is limited. Figure 1 As shown: A method for treating heavy metal wastewater by using microbial solidification of biochar materials, comprising the following steps:

[0056] Step 1: collecting heavy metal wastewater and pre-treating the collected heavy metal wastewater;

[0057] Specifically, comprehensive and targeted collection of sewage is the basis for ensuring the effectiveness of subsequent treatment. Heavy metal sewage from different sources, such as industrial wastewater, mine tailings wastewater, electronic waste treatment wastewater, etc., contains very different types of heavy metals, concentrations and other impurities. Accurate collection of sewage samples can provide a basis for subsequent precise analysis of sewage characteristics and selection of appropriate treatment parameters. For example, if the collected sewage is from an electroplating plant, it is rich in heavy metals such as copper, nickel, and chromium; while the wastewater from a battery production plant is mainly composed of heavy metals such as lead and cadmium. A clear understanding of the source of sewage will help determine the approximate composition of heavy metals in sewage, thereby providing direction for determining the treatment plan. Among them, the pretreatment of the collected heavy metal sewage mainly includes filtration and pH adjustment.

[0058] Step 2: adding the microbial solidified biochar material into the reaction container in proportion according to the concentration of heavy metal ions in the heavy metal wastewater;

[0059] Specifically, different heavy metal wastewaters have very different heavy metal ion concentrations. Accurately measuring the heavy metal ion concentration in wastewater can reasonably control the amount of microbial solidification biochar material added. If the added amount is insufficient, the modified biochar, functional microorganisms and other components in the material cannot fully contact and react with the heavy metal ions, resulting in incomplete heavy metal removal, and the treated wastewater is difficult to meet the discharge or reuse standards. For example, when treating high-concentration copper-containing wastewater, if too little microbial solidification biochar material is added, the copper ion concentration cannot be reduced to below the discharge standard; conversely, if too much is added, although a higher heavy metal removal rate can be guaranteed, it will cause waste of materials and increase treatment costs. When treating low-concentration heavy metal wastewater, excessive Adding materials will significantly increase the treatment cost and reduce the economic efficiency of the treatment process; a reasonable addition ratio can ensure that the various components in the microbial solidification biochar material can fully play their role. The modified biochar can adsorb heavy metal ions with its rich functional groups and large specific surface area; functional microorganisms can reduce the toxicity of heavy metals by using their own tolerance, adsorption and conversion capabilities; intelligent responsive polymer coatings can adjust material properties according to changes in the sewage environment; quantum dots can monitor the concentration of heavy metal ions in real time; when the addition ratio is appropriate, these components work synergistically to efficiently remove heavy metal ions in sewage, so that the treated sewage meets the expected discharge standard or reuse standard, achieving good treatment effect and economic benefits;

[0060] Step 3: inject the pretreated heavy metal wastewater into the reaction vessel containing the microbial solidified biochar material, and stir the reaction for 3-8 hours at a temperature of 20-35° C. and a stirring speed of 100-200 r / min;

[0061] Among them, the reaction temperature is 20-35℃, which is suitable for the growth and metabolism of functional microorganisms (such as Bacillus and Pseudomonas). In this temperature range, the enzyme activity in the microorganism is relatively high, and it can efficiently carry out physiological activities such as adsorption and conversion of heavy metals. For example, if the temperature is too low (below 20℃), the enzyme activity will be inhibited, the microbial metabolism will slow down, and the adsorption and conversion capacity of heavy metals will decrease. If the temperature is too high (above 35℃), it will destroy the microbial cell structure and enzyme activity, causing microbial inactivation and affecting the treatment effect. The appropriate temperature is also conducive to maintaining the characteristics of the intelligent responsive polymer coating. The coating composed of the temperature-sensitive polymer N-isopropylacrylamide and the pH-sensitive polymer polyacrylic acid can make corresponding adjustments according to changes in the sewage environment within this temperature range, ensuring sufficient contact and reaction between the material and the heavy metal ions in the sewage, and improving the overall treatment performance of the material.

[0062] Among them, the stirring speed of 100-200r / min can fully mix the microbial solidified biochar material with the pretreated heavy metal sewage, ensuring that the modified biochar, functional microorganisms and other components in the material can be evenly dispersed in the sewage, increasing the contact opportunity with heavy metal ions; if the stirring speed is too low (lower than 100r / min), the material and sewage are not mixed evenly, and the heavy metal ions in some areas cannot fully react with the material, resulting in poor treatment effect; if the stirring speed is too high (higher than 200r / min), it will damage the fixed structure of functional microorganisms and the physical structure of biochar, affecting the material performance; the appropriate stirring speed can accelerate the diffusion rate of heavy metal ions in sewage, so that they are transferred to the surface of microbial solidified biochar materials more quickly, promote adsorption and conversion reactions, and improve treatment efficiency;

[0063] Among them, if the reaction time is too short (less than 3 hours), the adsorption effect of the modified biochar and the adsorption and conversion reaction of heavy metals by functional microorganisms cannot be fully carried out, resulting in a low heavy metal removal rate and it is difficult for the treated sewage to meet the standards; if the reaction time is too long (more than 8 hours), although it will further improve the heavy metal removal rate, it will increase the treatment cost, reduce the treatment efficiency, and cause problems such as microbial aging and material performance degradation; for example, after a long period of reaction, the metabolites of some microorganisms will accumulate, inhibiting their own growth and ability to treat heavy metals.

[0064] Step 4: After the reaction is completed, the treated microbial solidified biochar material is separated from the heavy metal wastewater by a combination of filtration and centrifugation;

[0065] Among them, the combination of filtration and centrifugal treatment combines the advantages of the two methods; filtration can quickly remove larger particles, protect centrifugal equipment, and reduce equipment wear; centrifugation deeply separates tiny particles that are difficult to handle by filtration, thereby improving the thoroughness of solid-liquid separation; this combination method can efficiently separate the treated microbial solidified biochar material from water, which not only ensures the quality of the treated water, but also is conducive to the recycling of microbial solidified biochar materials, reduces treatment costs, and is in line with the concept of sustainable development.

[0066] Step 5: Detect the heavy metal content of the separated heavy metal wastewater. If the concentration reaches the discharge standard, it will be discharged or reused; if the concentration does not reach the discharge standard, repeat the above treatment steps;

[0067] Specifically, when the test results show that the heavy metal concentration reaches the emission standard, the sewage can be discharged into natural water bodies or reused. Discharge can alleviate the pressure on sewage treatment facilities and realize the natural circulation of water resources; reuse can improve the utilization rate of water resources, such as reuse for cooling water in industrial production, urban landscape water, etc., reduce dependence on fresh water resources, reduce production costs, and realize sustainable utilization of water resources; if the concentration does not meet the emission standard, repeating the above treatment steps is an important means to ensure the quality of sewage treatment. Through multiple cycles of treatment, the heavy metal content in the sewage can be gradually reduced until the emission standard is met. This reflects the flexibility and reliability of the treatment process, ensuring that no matter how high the initial heavy metal concentration in the sewage is, it can be discharged or reused in compliance with the standards through continuous optimization. In actual operation, the problems existing in each treatment step will be analyzed based on multiple test results, and the addition amount of microbial solidified biochar materials, reaction time, temperature and other parameters will be adjusted to improve treatment efficiency and reduce the number of cycle treatments.

[0068] In one embodiment, specifically, in step 1, the pretreatment of the collected heavy metal wastewater includes filtration treatment and pH adjustment treatment, wherein the filtration treatment is performed through a filter screen with a pore size of 0.2-0.5 μm, and the pH adjustment treatment uses sodium hydroxide or hydrochloric acid solution to adjust the pH value of the filtered heavy metal wastewater to between 6 and 8;

[0069] Among them, the filtration treatment is carried out through a filter with a pore size of 0.2-0.5μm. This step is to remove large particles of impurities and suspended solids in the sewage. These impurities will clog the subsequent treatment equipment and affect the treatment efficiency. They may even cover the surface of the microbial solidified biochar material, hindering the contact between the material and the heavy metal ions and reducing the treatment effect. For example, if the sewage contains large particles such as mud, debris, etc., it will enter the treatment system directly without filtration, which will cause the stirring device in the reaction vessel to jam, affecting the stirring effect, making the material and sewage mixed unevenly, and thus affecting the removal efficiency of heavy metals.

[0070] Among them, the pH adjustment treatment uses sodium hydroxide or hydrochloric acid solution to adjust the pH value of the filtered heavy metal wastewater to between 6 and 8. This is because the functional microorganisms in the microbial solidification biochar material are more active within this pH range. Different microorganisms have certain requirements for the pH value of the living environment. If it exceeds the appropriate range, the metabolic activity of the microorganism will be inhibited, and even cause the death of the microorganism; for example, Bacillus and Pseudomonas have strong adsorption and conversion capabilities for heavy metals in an environment with a pH value of 6-8. In addition, the appropriate pH value also helps to maintain the stability of biochar and smart responsive polymer coatings, ensuring that the material can fully exert its adsorption effect on heavy metals. If the pH value of the sewage is too high or too low, it will destroy the functional group structure on the surface of the biochar, affect its adsorption performance for heavy metals, and also cause the function of the smart responsive polymer coating to fail.

[0071] In one embodiment, specifically, in step 2, the microbial solidification biochar material is added to the reaction container in proportion, and the microbial solidification biochar material is added in a proportion of 0.1-0.5 g per liter of heavy metal wastewater;

[0072] Among them, microbial solidification biochar materials are generally added at a ratio of 0.1-0.5g of microbial solidification biochar materials per liter of heavy metal wastewater. However, in actual applications, it is necessary to adjust according to the specific conditions of the wastewater. When the concentration of heavy metal ions in the wastewater is high, the amount of material added can be appropriately increased, close to 0.5g / L; if the concentration is low, the amount added can be reduced, close to 0.1g / L; at the same time, factors such as the type of heavy metals in the wastewater and other coexisting substances need to be considered; for example, if the wastewater contains a large amount of organic matter in addition to heavy metal ions, these organic matter will interact with the microbial solidification biochar material and affect its adsorption and conversion of heavy metals. At this time, the amount of material added needs to be appropriately increased to ensure the treatment effect.

[0073] In one embodiment, specifically, in step 4, the filtration and centrifugation are combined as follows:

[0074] First, filter through a filter membrane with a filtration accuracy of 0.1-0.3μm, and then centrifuge at a speed of 3000-5000r / min for 5-10 minutes;

[0075] Among them, it is first filtered through a filter membrane with a filtration accuracy of 0.1-0.3μm. This is mainly to preliminarily separate larger particles of microbial solidified biochar materials and some agglomerated impurities. The microbial solidified biochar materials will form certain agglomerates after the reaction. These larger solid particles can be quickly separated from the treated sewage through filtration, reducing the burden of subsequent centrifugal treatment. At the same time, filtration can also remove some insoluble impurities in the sewage and further purify the water quality; for example, during the reaction process, the microbial solidified biochar materials will adsorb some suspended particles in the sewage. Filtration can effectively intercept these substances to prevent them from entering the subsequent treatment links or being discharged with water to avoid secondary pollution; moreover, the filtration process is relatively simple to operate and low in cost, and initial solidification can be achieved in a relatively short time. Liquid separation; then centrifuge at a speed of 3000-5000r / min for 5-10 minutes, using the centrifugal force generated by high-speed rotation to separate these tiny particles from the water. At high speed, the microbial solidified biochar material will settle to the bottom of the centrifuge tube due to centrifugal force, thereby achieving efficient separation from water. Through centrifugation, the content of residual microbial solidified biochar material in the treated sewage can be reduced to an extremely low level, greatly improving the purity of the water. For some reuse scenarios with high requirements on water quality, such as industrial circulating water, landscape water, etc., after centrifugal treatment, there are fewer solid particles and microbial solidified biochar materials remaining in the water, which can better meet the water quality standards. In addition, centrifugation can also concentrate the microbial solidified biochar material, which is convenient for subsequent recovery and regeneration of the material.

[0076] In one embodiment, specifically, in step five, the heavy metal content of the separated heavy metal wastewater is detected, and the concentration of heavy metal ions in the heavy metal wastewater is determined by atomic absorption spectroscopy; by using accurate detection methods such as atomic absorption spectroscopy to determine the concentration of heavy metal ions in heavy metal wastewater, the effect of wastewater treatment can be accurately judged, which is not only a test of the treatment process, but also a necessary measure to ensure environmental safety and rational use of water resources; for example, if it is detected that the lead ion concentration in the treated wastewater far exceeds the emission standard, direct discharge will cause serious pollution to the environment and affect the aquatic ecosystem and human health; if the test results meet the standards, it can be safely discharged or reused.

[0077] In one embodiment, specifically, in step three, a temperature control system is provided in the reaction vessel, and the reaction temperature is controlled within the range of ±2°C of the set temperature by a heating or cooling device; the reaction conditions for each sewage treatment are made consistent through precise temperature control, thereby improving the stability and repeatability of the treatment effect. In the sewage treatment process of different batches, as long as the same temperature conditions are maintained, the performance of the microbial solidification biochar material can be ensured to be stable, thereby obtaining a relatively consistent treatment result. This is of great significance for large-scale sewage treatment and is convenient for process control and quality monitoring in actual production. If the temperature fluctuates greatly and the results of each treatment are significantly different, it will be difficult to effectively manage and optimize the treatment process, increasing the uncertainty of meeting emission standards.

[0078] Embodiment 3

[0079] This embodiment provides a method for preparing a microbial solidified biochar material, which is as follows:

[0080] 1. Preparation of modified biochar: 100 g of biochar was added to 500 mL of 2 mol / L hydrochloric acid solution, stirred at 90 °C for 3 hours, and after the reaction, the biochar was rinsed with a large amount of deionized water until neutral, and then dried in an oven at 105 °C. The dried biochar was soaked in a 0.2 mol / L ferric nitrate solution for 18 hours, taken out and placed in a muffle furnace, and calcined at 400 °C for 2.5 hours to obtain modified biochar;

[0081] 2. Screening and immobilization of functional microorganisms: Samples were collected from soil contaminated by heavy metals, and Bacillus was isolated after a series of operations such as enrichment culture and plate screening. The Bacillus was inoculated into a liquid culture medium and cultured to the logarithmic growth phase at 30°C and 180 r / min in a shaking table. 10 mL of the bacterial liquid was mixed with 3 g of sodium alginate and 2 g of calcium chloride to prepare a mixed solution. The mixed solution was slowly dripped into a 2% calcium chloride solution by a syringe, and then frozen at -10°C for 1 hour, and then cross-linked and cured at 4°C for 4 hours to form adsorption-embedded composite fixed microbial particles;

[0082] 3. Material composite and modification: The prepared modified biochar is mixed with the fixed microbial particles in a mass ratio of 2:1, and stirred thoroughly in a blender. Then, a smart responsive polymer coating composed of a thermosensitive polymer N-isopropylacrylamide and a pH-sensitive polymer polyacrylic acid is coated on the surface of the composite material by spraying. Finally, cadmium sulfide quantum dots are chemically bonded to the surface of the modified biochar through a chemical coupling agent to obtain a microbial solidified biochar material.

[0083] This embodiment also provides a process for treating industrial wastewater containing lead and cadmium, which is as follows:

[0084] 1. Pretreatment: Collect 100L of industrial wastewater containing heavy metals such as lead and cadmium, first filter it through a filter with a pore size of 0.3μm to remove large particles of impurities, and then use sodium hydroxide solution to adjust the pH value of the filtered wastewater to 7;

[0085] 2. Material addition and reaction: According to the concentration test results of heavy metal ions in sewage, it is calculated that 0.3g of microbial solidified biochar material is added per liter of sewage. The required materials are added to the reaction vessel, and then the pretreated sewage is injected. A stirring paddle and a temperature control system are set in the reaction vessel, the stirring speed is controlled at 150r / min, the reaction temperature is controlled at 30°C, and the stirring reaction is carried out for 6 hours;

[0086] 3. Separation and detection: After the reaction is completed, the biochar is first filtered through a filter membrane with a filtration accuracy of 0.2 μm, and then the filtrate is centrifuged at a speed of 4000 r / min for 8 minutes to separate the treated microbial solidified biochar material from the water. The heavy metal content of the separated water is tested by atomic absorption spectroscopy. The results show that the removal rates of lead and cadmium are 92% and 88% respectively. The treated sewage meets the national emission standards and can be discharged directly;

[0087] 4. Material regeneration: The separated microbial solidified biochar material is soaked in 0.1 mol / L hydrochloric acid solution for 2 hours, then rinsed with deionized water, and dried in an oven before reuse.

[0088] Embodiment 4

[0089] This embodiment provides another method for preparing a microbial solidified biochar material, which is as follows:

[0090] 1. Preparation of modified biochar: Weigh 80 g of biochar, add it to 400 mL of 1 mol / L hydrochloric acid solution, stir and react at 80 °C for 4 hours, wash and dry, soak it in a solution of ferric nitrate and manganese nitrate mixed in a molar ratio of 1:1 with a total concentration of 0.1 mol / L for 24 hours, and then calcine it in a muffle furnace at 300 °C for 3 hours to obtain modified biochar;

[0091] 2. Screening and immobilization of functional microorganisms: Pseudomonas was screened from the polluted water samples, and after culturing to the logarithmic growth phase, 15 mL of bacterial solution was mixed with 4 g of sodium alginate and 3 g of calcium chloride, and then frozen and cross-linked (freezing temperature -15°C, cross-linking temperature 4°C, cross-linking time 3 hours) to form fixed microbial particles;

[0092] 3. Material compounding and modification: The modified biochar and the fixed microbial particles are compounded in a mass ratio of 3:1, stirred evenly, and coated with a smart responsive polymer coating by spraying, and cadmium sulfide quantum dots are chemically bonded;

[0093] This embodiment also provides a process for treating electroplating wastewater containing copper and zinc, which is as follows:

[0094] 1. Pretreatment: Collect 80L of electroplating wastewater containing copper and zinc, filter it with a filter with a pore size of 0.2μm, and then adjust the pH value of the wastewater to 6.5 with hydrochloric acid solution;

[0095] 2. Material addition and reaction: Add materials at a ratio of 0.2 g of microbial solidified biochar material per liter of sewage, in a reaction vessel, with a stirring speed of 120 r / min, a temperature of 25°C, and a reaction time of 5 hours;

[0096] 3. Separation and detection: First filter through 0.1μm filter membrane, then centrifuge at 3000r / min for 10 minutes for solid-liquid separation. Atomic absorption spectrometry shows that the copper removal rate is 89% and the zinc removal rate is 85%. The treated water meets the reuse standards and can be reused in the cleaning process of the electroplating workshop;

[0097] 4. Material regeneration: Soak the separated materials in 0.05 mol / L dilute sulfuric acid solution for 1.5 hours, wash and dry them for later use.

[0098] Comparing Example 3 and Example 4, there are both differences and similarities between the two in the preparation of microbial solidification biochar materials and the heavy metal wastewater treatment process, and these differences and similarities affect the treatment effect and application scenarios.

[0099] Comparison of material preparation:

[0100] 1. Differences in modified biochar: In Example 3, the hydrochloric acid concentration was 2 mol / L, the reaction was carried out at 90°C for 3 hours, and only ferric nitrate was used for soaking; in Example 4, the hydrochloric acid concentration was 1 mol / L, the reaction was carried out at 80°C for 4 hours, and the mixture of ferric nitrate and manganese nitrate was used for soaking; different acid treatment conditions and types of loaded metal oxides will cause different numbers and distributions of functional groups on the surface of modified biochar and the forms of loaded metal oxides, thus affecting its adsorption performance for heavy metals;

[0101] 2. Different functional microorganisms: Example 3 uses Bacillus, and Example 4 uses Pseudomonas; different strains have different adsorption, conversion capabilities and metabolic modes for heavy metals, which will lead to different treatment effects of the material on different heavy metals;

[0102] 3. Difference in material composite ratio: The mass ratio of modified biochar to fixed microbial particles in Example 3 is 2:1, and in Example 4 it is 3:1. The different composite ratios lead to different degrees of synergy between microorganisms and biochar, which in turn affects the overall material performance.

[0103] Comparison of sewage treatment processes:

[0104] 1. Differences in sewage types and pretreatment: Example 3 treats industrial sewage containing lead and cadmium, and the filter aperture is 0.3 μm during pretreatment, and the pH is adjusted to 7; Example 4 treats electroplating wastewater containing copper and zinc, and the filter aperture is 0.2 μm, and the pH is adjusted to 6.5; different sewage components and pretreatment conditions will affect the subsequent treatment process and effect;

[0105] 2. Different treatment parameters: In Example 3, 0.3 g of material was added per liter of sewage, the stirring speed was 150 r / min, the temperature was 30°C, and the reaction was carried out for 6 hours; in Example 4, 0.2 g of material was added per liter, the stirring speed was 120 r / min, the temperature was 25°C, and the reaction was carried out for 5 hours; these parameter changes will affect the activity of microorganisms, the reaction rate and degree of the material and heavy metals;

[0106] 3. Difference in treatment effect: In Example 3, the removal rates of lead and cadmium are 92% and 88% respectively, and the discharge meets the standards after treatment; in Example 4, the removal rates of copper and zinc are 89% and 85% respectively, and the treated water is reused in the electroplating workshop; the difference in treatment effect is due to the difference in materials and treatment processes, and also reflects the adaptability of the two embodiments under different sewage and treatment requirements.

[0107] In summary, both Example 3 and Example 4 are based on the treatment of heavy metal wastewater based on microbial solidification of biochar materials. The materials are prepared by modifying biochar, fixing functional microorganisms, coating intelligent responsive polymer coatings and bonding quantum dots, and the synergistic effect of the various components of the materials is used to adsorb and convert heavy metals. The treatment processes include wastewater pretreatment, material addition reaction, solid-liquid separation and detection, and the materials can be recycled, which solves the shortcomings of traditional heavy metal wastewater treatment methods, improves treatment efficiency and quality, and reduces costs and secondary pollution. Both embodiments have a high removal rate for heavy metals, and the treated wastewater meets the corresponding standards, achieving good economic and environmental benefits.

[0108] The basic principles of the present disclosure are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present disclosure are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present disclosure. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, and are not limitations. The above details do not limit the present disclosure to the necessity of adopting the above specific details to be implemented.

[0109] In the present disclosure, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. The block diagrams of the devices, devices, equipment, and systems involved in the present disclosure are only illustrative examples and are not intended to require or imply that they must be connected, arranged, and configured in the manner shown in the block diagram. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, and configured in any manner. Words such as "including", "comprising", "having", etc. are open words, referring to "including but not limited to", and can be used interchangeably with them. The words "or" and "and" used here refer to the words "and / or" and can be used interchangeably with them, unless the context clearly indicates otherwise. The words "such as" used here refer to the phrase "such as but not limited to", and can be used interchangeably with them.

[0110] Additionally, as used herein, "or" used in a list of items beginning with "at least one" indicates a separate list, so that, for example, a list of "at least one of A, B, or C" means A or B or C, or AB or AC or BC, or ABC (i.e., A and B and C). Furthermore, the word "exemplary" does not mean that the example described is preferred or better than other examples.

[0111] It should also be noted that in the system and method of the present disclosure, each component or each step can be decomposed and / or recombined. Such decomposition and / or recombination should be regarded as equivalent solutions of the present disclosure.

[0112] Various changes, substitutions, and modifications of the techniques described herein may be made without departing from the teachings defined by the appended claims. Furthermore, the scope of the claims of the present disclosure is not limited to the specific aspects of the processes, machines, manufactures, compositions of events, means, methods, and actions described above. Currently existing or later to be developed processes, machines, manufactures, compositions of events, means, methods, or actions that perform substantially the same functions or achieve substantially the same results as the corresponding aspects described herein may be utilized. Thus, the appended claims include such processes, machines, manufactures, compositions of events, means, methods, or actions within their scope.

[0113] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present disclosure. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present disclosure. Therefore, the present disclosure is not intended to be limited to the aspects shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0114] The above description has been given for the purpose of illustration and description. In addition, this description is not intended to limit the embodiments of the present disclosure to the forms disclosed herein. Although multiple example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, changes, additions and sub-combinations thereof.

Claims

1. A microbial solidification biochar material, characterized in that: These include modified biochar, functional microorganisms, smart responsive polymer coatings, and quantum dots; The modified biochar is obtained by first subjecting the biochar to acid treatment, introducing carboxyl groups and hydroxyl groups on its surface, and then subjecting it to metal oxide loading treatment; the functional microorganisms are screened, and strains with tolerance to heavy metals and adsorption and conversion capabilities are selected, mixed with an embedding agent and solidified by a freeze-crosslinking method to form adsorption-embedded composite fixed microbial particles, which are then composited with the modified biochar; the intelligent responsive polymer coating is coated on the surface of the composite modified biochar, and is composited with a thermosensitive polymer N-isopropylacrylamide and a pH-sensitive polymer polyacrylic acid; the quantum dots are connected to the surface of the modified biochar by chemical bonding.

2. The microbial solidification biochar material according to claim 1, characterized in that: The acid treatment uses a hydrochloric acid solution with a concentration of 1-3 mol / L, and reacts at 80-100° C. with stirring for 2-4 hours.

3. The microbial solidification biochar material according to claim 1, characterized in that: During the metal oxide loading treatment, the metal salt solution used to soak the biochar is one of ferric nitrate and manganese nitrate or a mixture of the two in proportion, the metal salt concentration is 0.1-0.3 mol / L, the soaking time is 12-24 hours, the calcination temperature is 300-500°C, and the calcination time is 2-3 hours.

4. The microbial solidification biochar material according to claim 1, characterized in that: The functional microorganism is one or more of Bacillus and Pseudomonas; the quantum dots are cadmium sulfide quantum dots; and the embedding agent is a mixture of sodium alginate and calcium chloride in a certain proportion.

5. A method for treating heavy metal wastewater using the microbial solidification biochar material according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: collecting heavy metal wastewater and pre-treating the collected heavy metal wastewater; Step 2: adding the microbial solidified biochar material into the reaction container in proportion according to the concentration of heavy metal ions in the heavy metal wastewater; Step 3: inject the pretreated heavy metal wastewater into the reaction vessel containing the microbial solidified biochar material, and stir the reaction for 3-8 hours at a temperature of 20-35° C. and a stirring speed of 100-200 r / min; Step 4: After the reaction is completed, the treated microbial solidified biochar material is separated from the heavy metal wastewater by a combination of filtration and centrifugation; Step 5: Detect the heavy metal content of the separated heavy metal wastewater. If the concentration reaches the discharge standard, it will be discharged or reused; if the concentration does not reach the discharge standard, repeat the above treatment steps.

6. The method for treating heavy metal wastewater according to claim 5, characterized in that: In step one, the pretreatment of the collected heavy metal wastewater includes filtration treatment and pH adjustment treatment. The filtration treatment is performed through a filter with a pore size of 0.2-0.5 μm. The pH adjustment treatment uses sodium hydroxide or hydrochloric acid solution to adjust the pH value of the filtered heavy metal wastewater to between 6 and 8.

7. The heavy metal wastewater treatment method according to claim 5, characterized in that: In step 2, the microbial solidified biochar material is added into the reaction container in proportion, and the addition is carried out at a ratio of 0.1-0.5 g of microbial solidified biochar material per liter of heavy metal wastewater.

8. The method for treating heavy metal wastewater according to claim 5, characterized in that: In step 4, the filtration and centrifugation are combined as follows: First filter through a filter membrane with a filtration accuracy of 0.1-0.3μm, and then centrifuge at a speed of 3000-5000r / min for 5-10 minutes.

9. The method for treating heavy metal wastewater according to claim 5, characterized in that: In step five, the separated heavy metal wastewater is subjected to heavy metal content detection, and the concentration of heavy metal ions in the heavy metal wastewater is determined by atomic absorption spectroscopy.

10. The heavy metal wastewater treatment method according to claim 5, characterized in that: In step three, a temperature control system is provided in the reaction container, and the reaction temperature is controlled within the range of ±2°C of the set temperature by a heating or cooling device.

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