A mycelium bamboo-based biomass composite material and a method for treating lead-containing wastewater

Abstract

The application belongs to the technical field of water treatment, and specifically provides a mycelium bamboo-based biomass composite material and a lead-containing wastewater treatment method. The application effectively combines the mildness of microbial treatment and the high-efficiency adsorption of the biomass composite material by first using the microorganism Neurospora crassa to pretreat the lead-containing wastewater and then using the mycelium bamboo-based biomass composite material prepared under specific conditions to post-treat the lead-containing wastewater, so that the removal rate of heavy metal lead is finally improved, the cost is low, and the application is environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a mycelium bamboo-based biomass composite material and a method for treating lead-containing wastewater. Background Technology

[0002] With the accelerating pace of industrialization and the continuous development of the economy and society, the discharge of industrial wastewater is constantly increasing, posing a significant threat to the environment and human health. It is well known that industrial wastewater contains large amounts of heavy metal ions, such as mercury (Hg(II), Pb(II), Cd(II), Cu(II), and Cr(VI). These heavy metal ions damage soil, water, and air, threatening ecological balance. Furthermore, due to their non-biodegradability, strong permeability, and accumulation, heavy metal ions eventually reach the human body through the food chain, and once they reach a certain level, they will harm human health. In recent years, through the control of heavy metal pollution sources, heavy metal pollution in major water bodies in China has been significantly improved; however, the role of removing and tracking heavy metal ions in water remains a research hotspot in this field.

[0003] Heavy metal concentrations in industrial wastewater often far exceed environmental standards, and excessive emissions not only directly impact the sustainable development of the surrounding environment but also exacerbate the scarcity of Earth's resources. Furthermore, heavy metals can accumulate in soil over long periods, affecting the quality and safety of agricultural products and posing potential health risks in the food chain. With the acceleration of industrialization, heavy metal pollution has become increasingly prominent, thus urgently requiring effective treatment methods to remove heavy metal pollutants from industrial wastewater.

[0004] Currently, the main methods for treating heavy metals in industrial wastewater include: 1. Electrochemical treatment, such as electroflotation, which is widely used in mining wastewater treatment. However, electrochemical treatment of wastewater requires a large investment and expensive electricity supply, limiting its widespread application; 2. Chemical precipitation, which is simple and easy to implement but requires a large amount of precipitant to reduce metal ions to an acceptable discharge concentration, which can become a new source of pollution. It is also costly and has poor ability to select heavy metal ions; 3. Ion exchange, which involves exchanging ions in resin with metal ions to treat wastewater. A disadvantage is that synthetic resins may be severely damaged when treating wastewater contaminated with heavy metals; 4. Membrane separation, which utilizes pressure and membrane selectivity for separation, purification, and concentration. This includes nanofiltration membranes, reverse osmosis membranes, microfiltration membranes, and ultrafiltration membranes. While membrane separation is effective for wastewater treatment, membrane materials are susceptible to environmental pollution, leading to scaling and clogging, resulting in a short lifespan. Furthermore, membrane separation equipment typically requires high pressure and has relatively high energy consumption; 5. Adsorption methods utilize the physical and chemical adsorption properties of adsorbents to remove various pollutants from wastewater. This is currently a widely used and highly efficient wastewater treatment method; however, the performance of the adsorbent itself and its selection are crucial. Biological methods, such as microbial adsorption and phytoremediation, utilize microorganisms or plants to adsorb, redox, and convert heavy metal ions into non-toxic or low-toxic substances. These methods are environmentally friendly and easy to operate, but their disadvantages include the specificity of the strains, high cost, and low removal efficiency. Although there are many methods for treating heavy metals in industrial wastewater, their effectiveness varies considerably. Therefore, selecting an efficient method for removing heavy metals from industrial wastewater is a pressing technical problem. Summary of the Invention

[0005] To address the aforementioned problems in existing technologies, this invention provides a mycelium-based bamboo biomass composite material and a method for treating lead-containing wastewater. This invention's method for treating lead-containing wastewater combines the mildness of microbial treatment with the high adsorption efficiency of biomass composite materials, ultimately effectively improving the removal rate of heavy metal lead, while being low-cost and environmentally friendly.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for preparing a mycelium-based bamboo-based biomass composite material includes the following steps:

[0008] (1) Preparation of potato dextrose agar medium;

[0009] (2) The fungi were propagated based on the potato dextrose agar medium described in step (1);

[0010] (3) After culturing bamboo powder and charcoal powder with fungi in a liquid culture medium, the culture medium is removed to obtain fungal bamboo powder spheres;

[0011] (4) The fungal bamboo powder spheres obtained in step (3) are first dried, and then mixed and impregnated with ammonium chloride. After the reaction is completed, the solid material is collected. Finally, the mycelium bamboo-based biomass composite material is obtained by heating under a nitrogen atmosphere.

[0012] In step (1), the specific method for preparing the potato dextrose agar medium is as follows:

[0013] Add 200g of fresh potato chunks to deionized water, boil and stir continuously for 30 min, filter the solids, and bring the solution to a final volume of 1 L; add 20 g of glucose, 20 g of agar powder, 3 g of KH2PO4, 1.5 g of MgSO4·7H2O and trace amounts of thiamine to the solution, stir until completely dissolved, sterilize under high pressure (0.105 MPa), and allow the culture medium to cool naturally to prepare the potato glucose agar medium.

[0014] In step (2), the specific operation of fungal expansion culture is as follows: take a small piece of Cladosporium slant culture medium, put it into the potato dextrose agar medium, and then place it in a biochemical incubator at 28°C for 5-7 days to complete the fungal expansion culture.

[0015] In step (3), the liquid culture medium is prepared by the following method: 200g of fresh potato chunks are added to deionized water, boiled and stirred continuously for 30 min, the solid is filtered, and the solution is brought to a final volume of 1 L; 20 g of glucose, 3 g of KH2PO4, 1.5 g of MgSO4·7H2O and trace amounts of thiamine are added to the solution, stirred until completely dissolved, sterilized by high pressure (0.105MPa), and the culture medium is naturally cooled to obtain the liquid culture medium;

[0016] The bamboo powder carbon powder is prepared by the following method: the cleaned bamboo powder is dried in an oven at 60°C until the moisture is completely removed; the bamboo powder is heated to 600°C in a tube furnace at a heating rate of 5°C / min and held for 1 hour, with nitrogen atmosphere maintained throughout the process, thus obtaining the bamboo powder carbon powder.

[0017] Bamboo powder, carbon powder, and fungi were cultured in a liquid culture medium for 7 days.

[0018] In step (4), the fungal bamboo powder spheres are dried at 40-60℃;

[0019] The mass ratio of the fungal bamboo powder spheres to ammonium chloride is 1:1 to 1:3;

[0020] The conditions for the impregnation reaction are: reaction at 40-60℃ and 300-500 rpm for 3.5-5 hours;

[0021] The heating treatment is as follows: heat to 800°C at 5°C / min and hold for 2 hours.

[0022] The mycelium bamboo-based biomass composite material prepared by the method described above.

[0023] A method for treating lead-containing wastewater based on the aforementioned mycelium-based bamboo-based biomass composite material includes the following steps:

[0024] (S1) First, adjust the pH of the wastewater;

[0025] (S2) Add corn cob powder and sugarcane bagasse to the wastewater;

[0026] (S3) Add Neurospora crassa to the wastewater, stir thoroughly, and then let it stand to settle;

[0027] (S4) After centrifugation, filter the precipitate;

[0028] (S5) Add the mycelium bamboo-based biomass composite material to the water after the treatment in steps (S1)-(S4) for adsorption treatment, thus completing the treatment of lead-containing wastewater.

[0029] Among them, Neurospora crassa was provided by Beina Biotechnology Co., Ltd. as BNCCBNCC336772.

[0030] In step (S1), adjust the pH to 6-7;

[0031] In step (S2), the mass ratio of wastewater, corn cob powder, and sugarcane bagasse is 97:2:1. The purpose of adding corn cob powder and sugarcane bagasse is to increase nutrients and provide conditions for bacterial growth.

[0032] In step (S3), the amount of Neurospora crassa added is 1-10 g / L (wastewater) based on dry bacterial weight; stir thoroughly for 30 minutes, and let stand for 5 days to allow the bacteria to grow, flocculate and settle;

[0033] In step (S4), the centrifugation conditions are 200-500 r / min and the centrifugation time is 5 minutes.

[0034] In step (S5), the amount of mycelium bamboo-based biomass composite material added is 1-5 g / L;

[0035] The adsorption treatment specifically involves: first running the mixture in a constant temperature shaker at 150 rpm for 12 hours, and then centrifuging it at 2000 rpm for 5 minutes.

[0036] The present invention has the following beneficial effects:

[0037] This invention provides a method for treating lead-containing wastewater. The method involves first pretreating the lead-containing wastewater with the microorganism Neurospora crassa, and then posttreating the wastewater with a mycelium-based biomass composite material prepared under specific conditions. This effectively combines the mildness of microbial treatment with the high-efficiency adsorption of biomass composite materials, ultimately improving the removal rate of heavy metal lead. The method is low-cost and environmentally friendly. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 The images shown are scanning electron microscope images of different biochar composite materials; where a is the original bamboo powder carbon powder, b is the obtained fungal bamboo powder spheres, c is the composite material obtained in Comparative Example 1 (NHBC2-1), d is the material obtained in Example 1 (NHBC1-1), e is the material obtained in Example 2 (NHBC2-3), and f is the composite material NHBC2-3 (H) after adsorption is completed.

[0040] Figure 2 The image shows the surface morphology of the mycelium bamboo-based biomass composite material after adsorption and the elemental mapping diagram of the material surface; where a is an enlarged view of the surface morphology of the composite material (NHBC2-3(H)) after adsorption, and be is the elemental mapping diagram of different elements (C, O, N, Pb) on the surface of the composite material after adsorption.

[0041] Figure 3 The images show the FTIR spectra of different biochar composite materials.

[0042] Figure 4 The images show XPS spectra of different biochar composites; where a is the full spectrum of BC; b is the full spectrum of NHBC2-3; c is the full spectrum of NHBC2-3(H); d is the C1s spectrum of NHBC2-3; e is the O1s spectrum of NHBC2-3; f is the N1s spectrum of NHBC2-3; g is the Pb4f spectrum of NHBC2-3(H); and h is the N1s spectrum of NHBC2-3(H).

[0043] Figure 5 The images show the crystal structure characterization spectra of the original biochar and the biochar samples treated with ammonium chloride, where a is the X-ray diffraction spectrum and b is the Raman spectrum. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0045] Unless otherwise specified, all reagents involved in the specific embodiments of this invention are commercially available products and can be purchased through commercial channels.

[0046] Example 1

[0047] This embodiment provides a method for preparing mycelium-based bamboo biomass composite materials, including the following steps:

[0048] (1) Preparation of potato dextrose agar medium (PDA medium):

[0049] Wash and peel fresh potatoes, and weigh out 200 g of potato chunks. Add the potatoes to deionized water, boil and stir constantly for 30 min, filter out the solids, and bring the solution to a final volume of 1 L. Add 20 g of glucose, 20 g of agar powder, 3 g of KH₂PO₄, 1.5 g of MgSO₄·7H₂O, and a trace amount of thiamine to the solution, stir until completely dissolved, and maintain the natural pH. Then dispense the solution into 300 mL Erlenmeyer flasks and seal the mouths with sealing film. Finally, place the Erlenmeyer flasks in an autoclave and sterilize at 0.105 MPa and 121 °C for 20 minutes. After sterilization, pour the culture medium into plastic petri dishes in a laminar flow hood and allow it to cool naturally to prepare PDA culture medium.

[0050] (2) Fungal propagation:

[0051] Prepare 4-5 PDA culture plates as described above, and wipe the plates containing *Cladosporium clavatum* with 75% alcohol. Gloeophyllum trabeum (Item number BNCC143315, source CGMCC5.98, provided by Beina Chuanglian Biotechnology Co., Ltd.) On the surface of the test tube, in a clean bench, open the test tube and flame the opening with an alcohol lamp to ensure aseptic operation. Repeatedly flame the autoclaved inoculation spatula in an alcohol lamp flame. After cooling, cut small pieces of *Gyrodactylus* slant culture medium with the spatula and place them into PDA medium. Then, place the PDA medium in a 28℃ biochemical incubator for 5-7 days to complete the fungal propagation.

[0052] (3) Prepare an agar-free liquid culture medium according to step (1), store it in an Erlenmeyer flask, weigh 1.5 g of bamboo powder charcoal powder, add it to the Erlenmeyer flask, and then complete the sterilization process. Cut the fungi in the PDA culture medium with a sterilized inoculation spatula in a laminar flow hood and add it to the Erlenmeyer flask. Then, incubate the Erlenmeyer flask in a constant temperature shaker at 28℃ and 150 rpm for 7 days, remove the culture medium, and obtain fungal bamboo powder spheres;

[0053] Preparation of the liquid culture medium: 200g of fresh potato chunks were added to deionized water, boiled and stirred continuously for 30 min, the solid was filtered off, and the solution was brought to a final volume of 1 L; 20 g of glucose, 3 g of KH2PO4, 1.5 g of MgSO4·7H2O and trace amounts of thiamine were added to the solution, and stirred until completely dissolved. After autoclaving, the culture medium was allowed to cool naturally to obtain the liquid culture medium.

[0054] Preparation of bamboo powder carbon powder: The cleaned bamboo powder was dried in an oven at 60°C until all moisture was removed. Then, the bamboo powder was heated to 600°C in a tube furnace at a heating rate of 5°C / min and held for 1 hour, with nitrogen atmosphere maintained throughout the process.

[0055] (4) The fungal bamboo powder spheres obtained in step (3) are first dried at 60°C, and then mixed with ammonium chloride at a mass ratio of 1:1 for impregnation reaction. The mixture is kept at 50°C and 400 rpm for 4 hours. After the reaction is completed, the solid material is collected. Finally, the mixture is heated to 800°C at 5°C / min and kept for 2 hours under a nitrogen atmosphere to obtain the mycelium bamboo-based biomass composite material NHBC1-1.

[0056] Example 2

[0057] This embodiment provides another method for preparing mycelium bamboo-based biomass composite material. The only difference from Example 1 is that in step (4), the obtained fungal bamboo powder spheres are dried at 40°C; the fungal bamboo powder spheres are mixed with ammonium chloride at a mass ratio of 1:2 for impregnation reaction, and the impregnation reaction conditions are: reaction at 40°C and 500 rpm for 5 hours; other steps and operations are the same as in Example 1. This embodiment prepares mycelium bamboo-based biomass composite material NHBC2-3.

[0058] Example 3

[0059] This embodiment provides another method for preparing mycelium bamboo-based biomass composite material. The only difference from Example 1 is that in step (4), the obtained fungal bamboo powder spheres are dried at 50°C; the fungal bamboo powder spheres are mixed with ammonium chloride at a mass ratio of 1:3 for impregnation reaction, and the impregnation reaction conditions are: reaction at 60°C and 300 rpm for 3.5 hours; other steps and operations are the same as in Example 1.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that in step (4), the dried fungal bamboo powder spheres and ammonium chloride are mixed and impregnated in a mass ratio of 2:1, and the resulting composite material is NHBC2-1. All other processing steps are exactly the same as in Example 1.

[0062] Example 4

[0063] This embodiment provides a method for treating lead-containing wastewater based on the aforementioned mycelium-based bamboo-based biomass composite material, comprising the following steps:

[0064] (S1) Adjust the pH to 6-7 using potassium hydroxide or dilute nitric acid;

[0065] (S2) Add corn cob powder and sugarcane bagasse to the sewage, with the mass ratio of sewage, corn cob powder and sugarcane bagasse being 97:2:1;

[0066] (S3) Based on dry bacterial weight, add Neurospora crassa at a dosage of 1 g / L to the wastewater, stir thoroughly for 30 minutes, and let it stand to settle for 5 days;

[0067] (S4) Centrifuge at 200 r / min for 5 minutes and filter the precipitate;

[0068] (S5) Determine the lead content in the water after steps (S1) to (S4). When the lead content is less than 25 mg / L, add mycelium bamboo-based biomass composite material NHBC1-1 to the water after the above treatment for adsorption treatment. Specifically, first run the water in a constant temperature shaker at 150 rpm for 12 h, and then centrifuge it at 2000 r / min for 5 minutes; thus, the treatment of lead-containing wastewater is completed.

[0069] Example 5

[0070] This embodiment provides a method for treating lead-containing wastewater based on the aforementioned mycelium-based bamboo-based biomass composite material, comprising the following steps:

[0071] (S1) Adjust the pH to 6-7 using potassium hydroxide or dilute nitric acid;

[0072] (S2) Add corn cob powder and sugarcane bagasse to the sewage, with the mass ratio of sewage, corn cob powder and sugarcane bagasse being 97:2:1;

[0073] (S3) Based on dry bacterial weight, add 2 g / L of Neurospora crassa to the wastewater, stir thoroughly for 30 minutes, and let it stand for 5 days to settle.

[0074] (S4) Centrifuge at 400 r / min for 5 minutes and filter the precipitate;

[0075] (S5) Determine the lead content in the water after steps (S1) to (S4). When the lead content is between 25-150 mg / L, add mycelium bamboo-based biomass composite material NHBC2-3 to the water after the above treatment for adsorption treatment. Specifically, first run the water in a constant temperature shaker at 150 rpm for 12 h, and then centrifuge it at 2000 r / min for 5 minutes; thus, the treatment of lead-containing wastewater is completed.

[0076] Example 6

[0077] This embodiment provides a method for treating lead-containing wastewater based on the aforementioned mycelium-based bamboo-based biomass composite material, comprising the following steps:

[0078] (S1) Adjust the pH to 6-7 using potassium hydroxide or dilute nitric acid;

[0079] (S2) Add corn cob powder and sugarcane bagasse to the sewage, with the mass ratio of sewage, corn cob powder and sugarcane bagasse being 97:2:1;

[0080] (S3) Based on dry bacterial weight, add 3.5 g / L of Neurospora crassa to the wastewater, stir thoroughly for 30 minutes, and let it stand to settle for 5 days;

[0081] (S4) Centrifuge at 500 r / min for 5 minutes and filter the precipitate;

[0082] (S5) Determine the lead content in the water after steps (S1)-(S4). When the lead content is greater than 150 mg / L, add the mycelium bamboo-based biomass composite material obtained in Example 3 to the water after the above treatment for adsorption treatment. Specifically, first run it in a constant temperature shaker at 150 rpm for 12 h, and then centrifuge it at 2000 r / min for 5 minutes; thus, the treatment of lead-containing wastewater is completed.

[0083] Experimental Example

[0084] The microstructure of ammonium chloride-modified biochar was analyzed using scanning electron microscopy (SEM). Figure 1As shown, the SEM image of the original bamboo powder charcoal (BC) reveals an overall blocky structure with a few pores on the surface. Compared to BC, the SEM image of the obtained fungal bamboo powder spheres (HBC) shows a very obvious fragmented structure, with the surface pores disappearing and becoming smoother. This is because, as the fungi grow, they form a crisscrossing micro-network structure. During the experiment, a large number of binding sites for fixing bamboo powder appeared inside the hyphal network. Over time, the hyphae gradually encapsulate the bamboo powder, forming hyphae-bamboo powder composite spheres. The pores of the bamboo powder are also occupied by the hyphae, resulting in a finer, smoother, and non-porous SEM image. In contrast, after ammonium chloride doping treatment, the surface of the biochar becomes rougher and more disordered. The SEM image of the composite material (NHBC2-1) obtained in Comparative Example 1 shows a dispersed blocky structure with some surfaces having grooved structures, but the overall degree of erosion is low. After further increasing the doping ratio of ammonium chloride, the degree of erosion of the composite material (NHBC1-1) obtained in Example 1 deepens. When the doping ratio was increased to 2, the SEM image of the material (NHBC2-3) obtained in Example 2 showed a higher degree of etching. This is because ammonium chloride decomposes to produce HCl during high-temperature carbonization. During the etching reaction of HCl, the surface morphology and pore structure of the biochar were improved and further enhanced through chemical activation. Figure 1 f shows biochar (NHBC2-3(H)) obtained from filtering a lead solution, with fine particles and a mist-like appearance on its surface, demonstrating the occurrence of the adsorption process.

[0085] Further analysis was conducted on the magnified surface morphology of the mycelium-based biomass composite material after adsorption and the elemental mapping of the material surface (e.g., Figure 2 As shown in the figure, Pb is uniformly distributed on the surface of the composite material, which proves the adsorption effect of the mycelium bamboo-based biomass composite material on Pb.

[0086] Table 1 shows the specific surface area and average pore size of different biochar composites. It can be seen that BC has a less than ideal specific surface area, with an average pore size greater than 50 nm and a high proportion of macroporous structures. Due to the mycelial coating forming a more fragmented structure, the specific surface area of ​​HBC increases, while the average pore size decreases. The specific surface area of ​​modified biochar increases with the increase of ammonium chloride ratio, with an average pore size of around 3 nm, further indicating that biochar is a mesoporous material. Ammonium chloride, as a modifier, helps biochar form more mesoporous structures and increases the specific surface area, providing more adsorption sites for Pb(II) removal.

[0087] Table 1 - Specific surface area, average pore size, and pore volume of biochar

[0088]

[0089] Figure 3 The FTIR spectrum of the biochar composite material is shown. 3431 cm⁻¹ -1 The broad peak at 2723-2827 cm⁻¹ represents the overlap effect of -OH and the stretching vibration of NH. -1 The nearby peaks reflect the stretching of aliphatic CH. 1591 cm⁻¹ -1 The absorption peak at this location is attributed to the vibration of the C=C bond in the aromatic ring. After fungal degradation and ammonium chloride modification, the absorption peak at this location became more gradual and its range increased, indicating that the modification treatment was effective. (1353 cm⁻¹) -1 The peak at [location] reflects CN stretching. After treatment, this absorption peak is significantly enhanced, further demonstrating that the intensity of nitrogen-containing functional groups in biochar increases after nitrogen doping modification. 1110 cm⁻¹ -1 The peak is related to the CO group of the carboxyl group. 772 cm⁻¹ -1 The absorption peak at that point is caused by the out-of-plane bending vibration of CH in the aromatic structure of biochar.

[0090] To conduct a more comprehensive study on the surface chemical state and elemental composition of biochar, XPS analysis was performed on the material. In the XPS full spectrum of BC, distinct O1s and C1s peaks were observed. After the composite material was doped with ammonium chloride, an N1s peak appeared in the XPS full spectrum of NHBC2-3, indicating successful nitrogen doping and successful ammonium chloride modification. Figure 4 b). To further understand the elemental properties of biochar, high-resolution XPS spectra of C1s, O1s, and N1s of NHBC2-3 were fitted and plotted. Figure 4 The peak near 285.1 eV belongs to C1s and, through fitting, it is divided into two peaks: the CC / C=C peak at 284.7 eV and the CO / CN peak at 285.98 eV. After fitting and plotting the fine spectrum of the O1s peak, a CO peak was found at 531 eV, an OH peak at 532.3 eV, and a C=O peak at 533.7 eV. In the fine spectrum of N1s, nitrogen mainly exists in the form of graphitic nitrogen, pyrrole nitrogen, and pyridine nitrogen. After adsorption is complete, a Pb4f signal peak appears in the XPS full spectrum of NHBC2-3(H) in the range of 133-156 eV. Figure 4 c) This proves the successful adsorption of lead ions.

[0091] A distinct spin-orbit splitting peak was observed in the high-resolution fitted Pb4f spectrum. 5 / 2 (144 ev) and Pb4f 7 / 2 The orbital doublet at (139 eV) further confirms the occurrence of the adsorption process. Figure 4 g-4f). In the spectrum of Pb4f, the binding energy at 139 eV is higher than that of metallic lead (136.9 eV) and lead tetroxide (138.4 eV), indicating that Pb4f... 5 / 2 and Pb4f 7 / 2 The peaks at the specified locations are all attributed to PbO2. After adsorption, the valence state of lead ions changes from divalent to tetravalent, indicating that redox reaction occurs during adsorption, resulting in tetravalent lead on the biochar surface. After adsorption, the fine spectrum of the N1s phase of the biochar changes (…). Figure 4 (h) Pyridine nitrogen and graphitic nitrogen are present on the surface of biochar, while the original pyrrole nitrogen disappears, and a new peak appears at 406 eV. This may be because the biochar contains pyridine-type nitrogen oxides. The change in nitrogen content and the appearance of the nitrogen oxide peak further prove that there is a chemical force involved in the adsorption of Pb(II) by biochar.

[0092] Figure 5 X-ray diffraction spectra of pristine biochar and biochar samples treated with ammonium chloride are shown. Two peaks appear at 25.4° and 44.3°, belonging to the (002) and (100) crystal planes, respectively. The (002) crystal plane represents the disorder and incompleteness of the graphitic carbon crystal structure. After ammonium chloride doping, the diffraction peak of the (002) crystal plane broadens slightly and its relative intensity increases. This indicates that nitrogen atoms are introduced into the carbon framework, giving the biochar different atomic arrangements and surface energies, which may be more conducive to improving adsorption capacity. The (100) crystal plane represents the graphene layer, representing the rearrangement and order of the biochar structure. After doping, the (100) crystal plane becomes flatter, and the relative intensity of the diffraction peak decreases, indicating that the introduction of nitrogen disrupts the graphitic structure of the biochar, increasing the amount of amorphous carbon. The changes in the two crystal planes show that after ammonium chloride doping, the amorphous degree of the biochar increases, and the degree of graphitization decreases.

[0093] Raman spectra of raw biochar and biochar treated with ammonium chloride are as follows: Figure 5 As shown in b. At 1320cm -1 The D peak at position 1590 cm⁻¹, also known as the defect peak, reflects the degree of defects in the biochar lattice. -1 The characteristic peak at this location is the G peak, a relatively strong Raman peak in graphite, which usually indicates that some of the biochar has been graphitized. The ratio of the D peak to the G peak indicates the content of large aromatic rings, i.e., the degree of ordering of the biochar. (BC's I...) D / I G The value is 2.17, and as the ammonium chloride doping ratio increases, I... D / I G The value increases accordingly. NHBC2-3's I D / IG The value reached 2.52, indicating that ammonium chloride doping increased the number of defects or sp3-bonded carbon atoms. This also means it has more defects and less graphite structure. Biochar I D / I G The increase in the value may be due to the fact that ammonium chloride doping provides external nitrogen atoms to the biochar. During high-temperature pyrolysis, these nitrogen atoms are embedded into the sp2 hybrid orbitals of carbon atoms, reducing the sp2 hybridization degree of carbon and thus leading to the generation of defect sites and an increase in the degree of disorder in the biochar. Biochar with more defect sites can provide adsorption sites, making it easier to adsorb heavy metal ions and improve the adsorption effect.

[0094] The removal rate of lead ions from lead-containing wastewater after treatment using different composite materials in Examples 4-6 was tested, and the results are shown in Table 2.

[0095] Table 2 - Removal rate of lead ions from lead-containing wastewater treated by different composite materials

[0096]

[0097] As can be seen from Table 2, the lead removal rate was the highest in Example 6. This is because as the proportion of ammonium chloride added increased, the nitrogen content in the mycelium bamboo-based biomass composite material obtained in Example 3 increased, the number of available adsorption sites in the biochar increased, and the complexation of nitrogen-containing functional groups had an adsorption effect on lead ions, thus achieving the best treatment effect on lead-containing wastewater.

[0098] In summary, the method for treating lead-containing wastewater based on mycelial bamboo-based biomass composite material described in this invention first pre-treats the lead-containing wastewater using the microorganism Neurospora crassa, and then post-treats the lead-containing wastewater using mycelial bamboo-based biomass composite material prepared under specific conditions. This effectively combines the mildness of microbial treatment with the high-efficiency adsorption of biomass composite material, ultimately improving the removal rate of heavy metal lead. It is low-cost and environmentally friendly.

Claims

1. A method for treating lead-containing wastewater based on mycelium-based bamboo-based biomass composite materials, characterized in that, Includes the following steps: (S1) First, adjust the pH of the wastewater; (S2) Add corn cob powder and sugarcane bagasse to the wastewater; wherein the mass ratio of wastewater, corn cob powder and sugarcane bagasse is 97:2:1; (S3) Add Neurospora crassa to the wastewater, stir thoroughly, and then let it stand to settle; (S4) After centrifugation, filter the precipitate; (S5) Add mycelium bamboo-based biomass composite material to the water after treatment in steps (S1)-(S4) for adsorption treatment, thus completing the treatment of lead-containing wastewater; The preparation method of the mycelium bamboo-based biomass composite material includes the following steps: (1) Preparation of potato dextrose agar medium; (2) The fungus is propagated on the potato dextrose agar medium described in step (1); the fungus is *Cladosporium clavatum*. (3) After culturing bamboo powder and charcoal powder with fungi in a liquid culture medium for 7 days, the culture medium was removed to obtain fungal bamboo powder spheres; The liquid culture medium was prepared as follows: 200g of fresh potato chunks were added to deionized water, boiled and stirred continuously for 30 min, the solid was filtered off, and the solution was brought to a final volume of 1 L; 20g of glucose, 3g of KH2PO4, 1.5g of MgSO4·7H2O and trace amounts of thiamine were added to the solution, and stirred until completely dissolved. After autoclaving, the culture medium was allowed to cool naturally to obtain the liquid culture medium. The bamboo powder carbon powder is prepared by the following method: the cleaned bamboo powder is dried in an oven at 60°C until the moisture is completely removed; the bamboo powder is heated to 600°C in a tube furnace at a heating rate of 5°C / min and held for 1 hour, with nitrogen atmosphere maintained throughout the process, thus obtaining the bamboo powder carbon powder. (4) The fungal bamboo powder spheres obtained in step (3) are dried first, and then mixed and impregnated with ammonium chloride. The mass ratio of the fungal bamboo powder spheres to ammonium chloride is 1:1-1:

3. After the reaction is completed, the solid material is collected. Finally, the mycelium bamboo-based biomass composite material is obtained under a nitrogen atmosphere. The heating treatment is: heating to 800℃ at 5℃ / min and holding for 2 hours.

2. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (1), the specific method for preparing the potato dextrose agar medium is as follows: Add 200g of fresh potato chunks to deionized water, boil and stir continuously for 30 min, filter the solids, and bring the solution to a final volume of 1 L; add 20 g of glucose, 20 g of agar powder, 3 g of KH2PO4, 1.5 g of MgSO4·7H2O and trace amounts of thiamine to the solution, stir until completely dissolved, autoclave, and allow the culture medium to cool naturally to prepare the potato glucose agar medium.

3. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (2), the specific operation of fungal expansion culture is as follows: take a small piece of Cladosporium slant culture medium, put it into the potato dextrose agar medium, and then place it in a biochemical incubator at 28℃ for 5-7 days to complete the fungal expansion culture.

4. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (4), the fungal bamboo powder spheres are dried at 40-60℃; The conditions for the impregnation reaction are: reaction at 40-60℃ and 300-500 rpm for 3.5-5 hours.

5. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (S1), adjust the pH to 6-7.

6. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (S3), the amount of Neurospora crassa added is 1-10 g / L based on dry bacterial weight; stir thoroughly for 30 minutes and let stand to settle for 5 days; In step (S4), the centrifugation conditions are 200-500 r / min and the centrifugation time is 5 minutes.

7. The method for treating lead-containing wastewater according to claim 1, characterized in that, In step (S5), the amount of mycelium bamboo-based biomass composite material added is 1-5 g / L; The adsorption treatment specifically involves: first running the mixture in a constant temperature shaker at 150 rpm for 12 hours, and then centrifuging it at 2000 rpm for 5 minutes.

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