Application of rhizopus oryzae nanofiber living gel in lignocellulose biorefinery wastewater treatment

Abstract

The invention discloses application of rhizopus oryzae nanofiber living gel in lignocellulose biorefinery wastewater treatment, the rhizopus oryzae nanofiber living gel is prepared by rhizopus oryzae fermentation, and nanofibers are additionally added into a fermentation medium in the middle and later periods of the fermentation process. The rhizopus oryzae nanofiber living gel is added into lignocellulose bio-refinery wastewater for wastewater biological treatment, lignin in the wastewater is adsorbed in the process that the living gel treats the lignocellulose bio-refinery wastewater, and the living gel attached with the lignin has the photo-thermal conversion capacity and can be used as a photo-thermal material for secondary utilization. According to the method, the rhizopus oryzae nanofiber living gel is applied to treatment of the lignocellulose bio-refinery wastewater, effective treatment of the lignocellulose bio-refinery wastewater is achieved, the wastewater treatment method is high in operability, secondary pollution is avoided, and the economic cost of wastewater treatment is reduced.

Description

Technical Field

[0001] The present invention belongs to the technical field of wastewater biological treatment, and particularly relates to the application of Rhizopus oryzae nanofiber living gel in the treatment of lignocellulosic biorefinery wastewater. Background Art

[0002] Rhizopus oryzae, as one of the important molds in Chinese medicine and koji, can saccharify starch, convert sucrose, and produce lactic acid, organic acids and trace amounts of alcohol. As a new type of biomass nanomaterial, nanocellulose not only has the characteristics of natural cellulose such as renewable and biodegradable, but also has advantages such as large specific surface area, high hydrophilicity, high transparency, high strength, high Young's modulus, and low thermal expansion coefficient, which provides the possibility for the formation of various functional composite materials. It has been proven to be a self-assembled hydrogel or bio-based nanofiller with broad prospects.

[0003] Hydrogel is a kind of polymer material with a three-dimensional network structure made of synthetic polymers and natural polymers. It can absorb a large amount of liquid in a short time and retain the liquid without being dissolved. Due to its high water content and high elastic behavior, hydrogels are widely used in tissue filling materials, drug carriers, cartilage regeneration, wound dressings and environmental adsorbents, etc.

[0004] Living hydrogel is a material that embeds living cells (such as microorganisms, enzymes or functional cells) in a three-dimensional polymer network structure, which not only retains the structural function of the gel but also endows biological activity. Currently, the commonly used matrix materials include common natural polymers (such as sodium alginate, chitosan, gelatin) or synthetic polymers (such as polyethylene glycol diacrylate). Functional materials (such as nanocellulose, graphene oxide) improve the mechanical properties and biocompatibility of the gel. By combining them with biological materials and using extracellular polysaccharides or proteins secreted by microorganisms (such as fungi, bacteria) as the gel matrix, "self-assembled" living gels are formed. The preparation methods include physical crosslinking, chemical crosslinking and 3D printing technology. It can be applied to pollutant degradation, catalysis and energy conversion, and the biomedical field.

[0005] The sewage generated in the lignocellulosic biorefinery process is characterized by high concentrations of COD (chemical oxygen demand), high concentrations of BOD (biochemical oxygen demand), and complex components. The treatment difficulties include: 1. High-molecular organic substances (lignin, cellulose decomposition products); 2. Difficult-to-degrade components: Lignin derivatives (such as phenol, methoxybenzene) have strong anti-degradability; 3. High biological toxicity: Certain intermediate products (such as aldehydes, organic acids) may be toxic to microorganisms. The traditional activated sludge method has limited treatment effects on difficult-to-degrade pollutants such as lignin derivatives; high-toxicity and high-concentration pollutants will inhibit the activity of conventional microorganisms; the organic wastewater by-products generated during the treatment process are not fully utilized, resulting in waste of resources and high economic and environmental costs. Moreover, traditional treatment methods (such as chemical oxidation, physical adsorption) require high energy consumption or expensive chemical reagents, which is not conducive to large-scale promotion. In addition, the traditional lignocellulosic biorefinery wastewater treatment process will generate a large amount of solid waste, causing secondary pollution and being unfavorable to environmental protection.

[0006] The lignin photothermal conversion technology is a technology that uses light energy to accelerate the decomposition of lignin and produce useful products, and has broad application prospects, especially in energy production and environmental protection. The basic principle of photothermal conversion is to irradiate a lignin material with a specific light source (such as sunlight, laser, or visible light, etc.). By absorbing light energy, the temperature of the material increases, which then leads to the pyrolysis or chemical reaction of lignin molecules. Through the synergistic effect of the photothermal effect and photocatalysis, the lignin conversion efficiency can be improved, promoting the efficient utilization of biomass resources. Although lignin itself has certain light absorption characteristics, its photothermal conversion efficiency is usually low.

[0007] Therefore, aiming at the problems existing in the treatment of high-COD and BOD sewage in the field of lignocellulosic biorefinery, it is urgent to develop a lignocellulosic biorefinery wastewater treatment technology with excellent wastewater treatment effect, low cost, and environmental friendliness. Summary of the Invention

[0008] The purpose of the present invention is to provide a lignocellulosic biorefinery wastewater treatment technology with excellent wastewater treatment effect, low cost, and environmental friendliness for the problems that the existing technology cannot effectively and economically treat lignocellulosic biorefinery wastewater and will cause secondary pollution to the environment.

[0009] In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] An application of Rhizopus oryzae nanofiber living gel in the treatment of lignocellulosic biorefinery wastewater, wherein the Rhizopus oryzae nanofiber living gel is prepared by fermenting Rhizopus oryzae, and nanofibers are additionally added to the fermentation medium in the middle and later stages of the fermentation process.

[0011] Among them, the Rhizopus oryzae nanofiber living gel is prepared by the following method: inoculate the seed liquid of Rhizopus oryzae into the fermentation medium at a volume ratio of 1% - 10%, and carry out fermentation under the conditions of a temperature of 30 - 40°C and a certain rotation speed; before adding the nanofibers to the fermentation medium, the rotation speed is 120 - 300 rpm; after adding the nanofibers to the fermentation medium, the rotation speed is 40 - 70 rpm;

[0012] Preferably, the Rhizopus oryzae nanofiber living gel is prepared by the following method: inoculate the seed liquid of Rhizopus oryzae into the fermentation medium at a volume ratio of 5%, and carry out fermentation under the conditions of a temperature of 30 - 40°C and a certain rotation speed; before adding the nanofibers to the fermentation medium, the rotation speed is 120 - 300 rpm; after adding the nanofibers to the fermentation medium, the rotation speed is 40 - 70 rpm.

[0013] Among them, adding nanofibers to the fermentation medium additionally in the middle and later stages of the fermentation process means adding nanofibers to the fermentation medium after 10 - 72 h of fermentation, and continuing fermentation for 2 - 20 h; preferably, adding nanofibers to the fermentation medium after 60 h of fermentation and continuing fermentation for 12 h.

[0014] Among them, the nanofibers are any one of nanocellulose, cellulose nanocrystals, and chitin nanofibers, preferably nanocellulose. The carboxyl content in the nanocellulose, cellulose nanocrystals, and chitin nanofibers needs to be 0.8 - 1.5 mmol / g. The nanocellulose can be prepared by the method in the reference (Tang X, Liu L, Wang Z, et al. A honeycomb-like hydrogel in-situ constructed by Streptococcus zooepidemicus and TOCN for the proliferation of bacteria[J]. Carbohydrate Polymers, 2022, 281:119099). The prepared nanocellulose has a negative charge on its surface, and its size is: L (length): 200 - 500 nm, D (diameter): 10 - 20 nm; the carboxyl content is 1.17 mmol / g; the Zeta potential is -49 ± 1 mV. It can also be obtained by purchasing from the market. The cellulose nanocrystals and chitin nanofibers can be obtained by purchasing from the market.

[0015] Among them, the nanofibers are added to the fermentation medium in the form of a nanofiber dispersion; the nanofiber dispersion is a dispersion formed by the nanofibers in water; the mass fraction of the nanofibers in the nanofiber dispersion is 0.1% - 2%, preferably 0.5% - 2%; adding the nanofiber dispersion to the fermentation medium to obtain a mixed system, the mass fraction of the nanofibers in the mixed system is 0.1% - 1%, preferably 0.5%.

[0016] Among them, the Rhizopus oryzae includes but is not limited to Rhizopus oryzae ATCC20344.

[0017] Among them, the components of the fermentation medium include: 10 - 40 g / L glucose, 0 - 1 g / L (NH 4 ) 2 SO 4 , 0 - 1 g / L KH 2 PO 4 , 0 - 0.1 g / L FeSO 4 , 0.1 - 1 g / L MgSO 4 , 0 - 0.1 g / L ZnSO 4 , 10 - 40 g / L CaCO 3 and 1 - 7% v / v citrate buffer; preferably, the components of the fermentation medium include: 40 g / L glucose, 0.71 g / L (NH 4 ) 2 SO 4 , 0.6 g / L KH 2 PO 4 , 0.004 g / L FeSO 4 ·7H 2 O, 0.5 g / L MgSO 4 ·7H 2 O, 0.01 g / L ZnSO 4 ·7H 2 O, 30 g / L CaCO 3 and 5% v / v citrate buffer.

[0018] Among them, the components of the medium of the seed liquid include: 10 - 40 g / L glucose, 2 - 5 g / L (NH 4 ) 2 SO 4 , 0.2 - 1 g / L KH 2 PO 4 , 0 - 0.01 g / L FeSO 4 ·7H 2 O, 0 - 1 g / L MgSO 4 ·7H2 O and 0 - 0.2 g / L ZnSO 4 ·7H 2 O; Preferably, the components of the culture medium of the seed liquid include: 40 g / L glucose, 4.4 g / L (NH 4 ) 2 SO 4 , 0.6 g / L KH 2 PO 4 , 0.005 g / L FeSO 4 ·7H 2 O, 0.5 g / L MgSO 4 ·7H 2 O and 0.018 g / L ZnSO 4 ·7H 2 O.

[0019] The present invention uses Rhizopus oryzae as the main body, ferments in the fermentation medium to produce organic acid fumaric acid, and forms a living gel in cooperation with exogenously added nanofibers (the organic acid provides hydrogen bonds for gel formation), and puts the living gel into the lignocellulosic biorefinery wastewater for sewage treatment.

[0020] Among them, the lignocellulose is gramineous lignocellulose and / or ligneous lignocellulose, preferably gramineous lignocellulose.

[0021] Among them, the method of applying the Rhizopus oryzae nanofiber living gel to the treatment of lignocellulosic biorefinery wastewater is: adding the Rhizopus oryzae nanofiber living gel to the lignocellulosic biorefinery wastewater, and treating it for 1 - 10 days under the conditions of a temperature of 30 - 40 °C and a stirring speed of 50 - 80 rpm.

[0022] Preferably, the method of applying the Rhizopus oryzae nanofiber living gel to the treatment of lignocellulosic biorefinery wastewater is: adding the Rhizopus oryzae nanofiber living gel to the lignocellulosic biorefinery wastewater, and treating it for 6 days under the conditions of a temperature of 35 °C and a stirring speed of 70 rpm.

[0023] In the process of using the Rhizopus oryzae nanofiber living gel to treat the lignocellulosic biorefinery wastewater, the dosage of the living gel is not particularly limited, and the standard is that the lignocellulosic biorefinery wastewater submerges the living gel; preferably, for every 100 mL of lignocellulosic biorefinery wastewater, 3 - 4 cylindrical living gels with a diameter of about 2 cm and a height of 2 - 3 cm are added.

[0024] Among them, after using the Rhizopus oryzae nanofiber living gel to treat the lignocellulosic biorefinery wastewater, gel solid waste is obtained, and the gel solid waste is reused as a photothermal material.

[0025] Among them, the gel solid waste is reused as a photothermal material after being treated with laccase.

[0026] Nanocellulose materials (such as TEMPO-oxidized cellulose) can be used as hydrogel matrices, which can provide excellent mechanical strength and pore structure to support the growth and activity of Rhizopus oryzae. The stability and recycling ability of extracellular enzymes of Rhizopus oryzae are improved through immobilization technology, and the enzyme activity is enhanced. In addition, nanofiber-based gels can not only degrade organic matter through Rhizopus oryzae, but also adsorb heavy metals or toxic small molecules through the surface functional groups of cellulose.

[0027] The living gel of Rhizopus oryzae nanofibers has the following characteristics in the treatment of lignocellulosic biorefinery wastewater: 1. Efficient degradation of organic matter: Rhizopus oryzae can secrete various extracellular enzymes (such as xylanase, lipase, peroxidase), which can efficiently decompose lignin derivatives and other organic pollutants; 2. Reduction of the biological toxicity of pollutants: The nanofiber matrix provides a protective barrier for Rhizopus oryzae, reducing the toxic effect of high-concentration pollutants on Rhizopus oryzae; 3. Improvement of resource utilization rate: Lignin degradation products (such as phenolic compounds, short-chain organic acids) can be further metabolized by microorganisms to generate valuable chemicals.

[0028] The treatment of wastewater by the living gel of Rhizopus oryzae can be reflected in two aspects: 1. Biodegradation: The lignin-degrading enzymes and cellulases secreted by Rhizopus oryzae can break the chemical bonds (such as benzene rings, ether bonds) in complex macromolecular organic matter and convert them into simple small molecules (such as alcohols, phenols). 2. Physical adsorption: The nanofiber matrix has a high specific surface area and abundant functional groups (such as carboxyl groups, hydroxyl groups), and adsorbs oxygen-containing organic matter and heavy metals in wastewater through electrostatic interaction and hydrogen bonding.

[0029] Lignin itself has certain light absorption characteristics, but its photothermal conversion efficiency is usually low. After adding laccase to it, lignin undergoes an oxidation reaction under the catalytic action of laccase to form more active oxidation products (such as quinones, free radicals, etc.). These oxidation products have stronger light absorption ability and a wider light absorption wavelength range, thus enhancing the light absorption ability of the gel and further improving its photothermal conversion efficiency. The role of nanofibers in enhancing the photothermal conversion of living gels can be attributed to the following points: improving light absorption and scattering ability, increasing thermal conductivity, providing more surface functional groups, promoting the formation of composite materials, and the synergistic effect with photothermal materials. These characteristics make nanocellulose an ideal enhancer, which helps to improve the efficiency of living gels in photothermal conversion and expand their application potential in the fields of environmental protection, energy conversion, etc. When lignin is adsorbed onto the surface of nanofibers and treated with laccase, the oxidation products of lignin will interact with the nanofibers to form a more compact composite structure. This structure is more conducive to light absorption and heat accumulation, improving the photothermal conversion efficiency of the gel. At the same time, laccase not only promotes the oxidation of lignin, but may also crosslink with some functional groups (such as phenolic hydroxyl groups, amino groups, etc.) in the Rhizopus oryzae nanofiber gel, further enhancing the stability and structural integrity of the material. This crosslinking effect causes the structure of the gel to become denser, thus improving its heat accumulation effect under light irradiation.

[0030] Rhizopus oryzae mycelia itself has good adsorption ability for organic pollutants (such as lignin), and the composite material formed after Rhizopus oryzae nanofiber gel adsorbs lignin has stronger photothermal properties than pure nanofibers. After Rhizopus oryzae mycelia adsorb lignin, it promotes the distribution of lignin oxidation products, making them more evenly distributed in the gel structure, thus enhancing the overall photothermal conversion efficiency of the gel. Further through the catalytic action of laccase, lignin and its oxidation products can absorb light more efficiently and convert it into heat energy. Since these products are evenly distributed in the gel and interact with nanofibers, this local photothermal effect is more concentrated, thus enhancing the overall photothermal effect of the gel. Rhizopus oryzae mycelia itself is also a biocatalyst. In some cases, it can act synergistically with the oxidation process of lignin to help lignin be oxidized by laccase more quickly and efficiently. This synergistic effect further improves the photothermal conversion efficiency of lignin.

[0031] The Rhizopus oryzae nanofiber-based living gel combines the high degradation ability of Rhizopus oryzae with the structural advantages of nanofibers, providing a green, efficient and sustainable solution for the treatment of high-COD and BOD sewage generated in the field of lignocellulose biorefinery. It can not only significantly improve the treatment efficiency and reduce environmental pressure, but also realize the recycling of resources in wastewater and the secondary utilization of solid waste, providing strong support for the sustainable development of biorefinery processes.

[0032] Beneficial effects:

[0033] 1. The present invention applies the living gel of Rhizopus oryzae nanofibers to the treatment of lignocellulosic biorefinery wastewater. The living gel degrades and removes organic pollutants in the wastewater through biodegradation and physical adsorption, effectively reducing the COD and BOD contents in the wastewater, achieving effective treatment of lignocellulosic biorefinery wastewater, and the wastewater treatment method has strong operability.

[0034] 2. The present invention applies the living gel of Rhizopus oryzae nanofibers to the treatment of lignocellulosic biorefinery wastewater. The used living gel adsorbs lignocellulose, making it have the ability of photothermal conversion and can be reused as a photothermal material. This not only avoids the generation of secondary pollution during the wastewater treatment process but also reduces the economic cost of wastewater treatment. Description of the drawings

[0035] The following further specifically describes the present invention in conjunction with the drawings and specific embodiments, and the above and / or other advantages of the present invention will become clearer.

[0036] Figure 1 Photographs of the living gel of Rhizopus oryzae nanofibers in Example 3 and the gel solid waste formed after its use for wastewater treatment; among them, Figure a is a photograph of the living gel of Rhizopus oryzae nanofibers; Figure b is a photograph of the gel solid waste.

[0037] Figure 2 SEM images of the living gel of Rhizopus oryzae nanofibers in Example 3 and the gel solid waste formed after its use for wastewater treatment; among them, Figure a is the SEM image of the living gel of Rhizopus oryzae nanofibers; Figure b is the SEM image of the gel solid waste.

[0038] Figure 3 COD and BOD in the gramineous lignocellulosic cooking wastewater before and after treatment with the living gel of Rhizopus oryzae nanofibers in Example 3 5 Content statistical chart.

[0039] Figure 4 Photographs of the verification experiment on the photothermal conversion effect of the living gel of Rhizopus oryzae nanofibers, gel solid waste, and gel solid waste treated with laccase in Example 4.

[0040] Figure 5 Evaporation effect diagram of water by the gel solid waste treated with laccase as a solar evaporator in Example 5; among them, Figure a is the statistical chart of the temperature change of the gel solid waste treated with laccase during sunlight irradiation; Figure b is the statistical chart of the mass change rate of water during sunlight irradiation; Figure c is the experimental photograph of the temperature measurement of the gel solid waste treated with laccase during sunlight irradiation. Specific embodiments

[0041] The present invention will be further described according to the following embodiments. It should be understood that the following embodiments are only used to illustrate the present invention and do not limit the present invention.

[0042] For specific technologies or conditions not specified in the embodiments, they shall be in accordance with the technologies or conditions described in the literature in this field or in accordance with the product instructions. For reagents or instruments whose manufacturers are not specified, they are all conventional products that can be obtained through regular channels.

[0043] The Rhizopus oryzae used in the following embodiments is Rhizopus oryzae ATCC20344.

[0044] The formula of the seed medium used in the following embodiments is: glucose 40 g / L, (NH 4 ) 2 SO 4 4.4 g / L, KH 2 PO 4 0.6 g / L, FeSO 4 ·7H 2 O 0.005 g / L, MgSO 4 ·7H 2 O 0.5 g / L, ZnSO 4 ·7H 2 O 0.018 g / L. Sterilize in advance.

[0045] The formula of the fermentation medium used in the following embodiments is: glucose 40 g / L, (NH 4 ) 2 SO 4 0.71 g / L, KH 2 PO 4 0.6 g / L, FeSO 4 ·7H 2 O 0.004 g / L, MgSO 4 ·7H 2 O 0.5 g / L, ZnSO 4 ·7H 2 O 0.01 g / L, CaCO 3 3 0 g / L, citric acid buffer 5% v / v. Sterilize in advance.

[0046] The lignocellulosic biorefinery wastewater processed in the following examples is the cooking wastewater of gramineous lignocellulose (corn stover), which is the wastewater generated by hydrothermal pretreatment of corn stover. The wastewater generated by hydrothermal pretreatment of corn stover: taking 170 °C as the pretreatment temperature, adding 50 g of dry 20-80 mesh corn stover and 500 mL of water into the oil bath tank, first heating the temperature of the oil bath to 60 °C and keeping it warm for 30 min, and fully mixing the internal solid-liquid mixture, then heating it to 170 °C at a rate of 1 °C / min. Record the time when the target temperature is reached, and then keep it warm at 170 °C for 40 min. After the hydrothermal pretreatment is completed and the tank body is cooled, solid-liquid separation is carried out with a cloth bag or a glass sand funnel to obtain the cooking wastewater of gramineous lignocellulose (corn stover).

[0047] In the following examples, the particle size of the nanofibers is 200-500 nm.

[0048] In the following examples, the "%" refers to mass percentage content unless otherwise specified.

[0049] In the following examples, the solvent of the nanocellulose dispersion is distilled water.

[0050] Example 1 Preparation of Rhizopus oryzae nanocellulose living gel

[0051] (1) Inoculate the slant-cultured Rhizopus oryzae stored in a 4 °C refrigerator into the seed medium, and culture it at 35 °C and 200 rpm for 24 hours to obtain the Rhizopus oryzae seed liquid;

[0052] (2) Inoculate the obtained Rhizopus oryzae seed liquid into a shake flask containing 100 mL of fermentation medium, and the inoculation amount is 5% v / v. Culture it on a shaker, and the culture conditions are: rotation speed 130 rpm, fermentation temperature 30 °C, and culture time 10 h;

[0053] (3) Directly pour the nanocellulose dispersion with a concentration of 1% into the fermentation medium that has been fermented for 10 h in step (2), so that the final concentration of nanocellulose in the mixed system is 0.1%, reduce the rotation speed to 70 rpm, and continue to culture for 2 h. Finally, a light white gel-like substance can be obtained, which is the Rhizopus oryzae nanocellulose living gel. However, the strength of this gel-like substance is too low to maintain its shape.

[0054] Example 2 Preparation of Rhizopus oryzae nanocellulose living gel and its application in the treatment of lignocellulosic biorefinery wastewater

[0055] Preparation of Rhizopus oryzae nanocellulose living gel:

[0056] (1) Inoculate the slant-cultured Rhizopus oryzae stored in a 4 °C refrigerator into the seed medium, and culture it at 35 °C and 200 rpm for 24 hours to obtain the Rhizopus oryzae seed liquid;

[0057] (2) Inoculate the obtained Rhizopus oryzae seed liquid into a shake flask containing 100 mL of fermentation medium, with an inoculation amount of 5% v / v. Incubate on a shaker, and the incubation conditions are: rotation speed of 130 rpm, fermentation temperature of 40 °C, and incubation time of 72 h;

[0058] (3) Directly pour the 1% nanocellulose dispersion into the fermentation medium that has been fermented for 72 h in step (2), so that the final concentration of nanocellulose in the mixed system is 0.2%. Reduce the rotation speed to 70 rpm and continue to incubate for 20 h. Finally, a light white gel-like substance can be obtained, which is the Rhizopus oryzae nanocellulose living gel;

[0059] Put the living gel prepared through the above steps into the Gramineae lignocellulose cooking waste liquid for treatment for 6 days. The temperature during the treatment process is 40 °C, and the rotation speed is 70 rpm. After the wastewater treatment is completed, a dark brown living gel can be finally obtained.

[0060] Example 3 Preparation of Rhizopus oryzae nanocellulose living gel and its application in the treatment of lignocellulose biorefinery wastewater

[0061] Preparation of Rhizopus oryzae nanocellulose living gel:

[0062] (1) Inoculate the slant-cultured Rhizopus oryzae stored in a 4 °C refrigerator into the seed medium, and incubate at 35 °C and 200 rpm for 24 hours to obtain the Rhizopus oryzae seed liquid;

[0063] (2) Inoculate the obtained Rhizopus oryzae seed liquid into a shake flask containing 100 mL of fermentation medium, with an inoculation amount of 5% v / v. Incubate on a shaker, and the incubation conditions are: rotation speed of 150 rpm, fermentation temperature of 35 °C, and incubation time of 60 h;

[0064] (3) Directly pour the 1% nanocellulose dispersion into the fermentation medium that has been fermented for 60 h in step (2), so that the final concentration of nanocellulose in the mixed system is 0.5%. Reduce the rotation speed to 70 rpm and continue to incubate for 12 h. Finally, a light white gel-like substance can be obtained, which is the Rhizopus oryzae nanocellulose living gel.

[0065] Put the living gel prepared through the above steps into the Gramineae lignocellulose cooking wastewater (add 3 - 4 cylinder-shaped living gels with a diameter of about 2 cm and a height of 2 - 3 cm per 100 mL of wastewater), and react for 6 days. The temperature during the reaction process is 35 °C, and the rotation speed is 70 rpm. After the wastewater treatment is completed, the living gel that adsorbs lignin in the adsorption waste liquid, that is, the gel solid waste, is obtained. Characterize the morphology and microstructure of the Rhizopus oryzae nanocellulose living gel prepared in this example and the gel solid waste formed after its use in wastewater treatment. Figure 1Photographs of the living gel of Rhizopus oryzae nanocellulose and the gel solid waste formed after its use in wastewater treatment. It can be clearly seen from the figure that the initial living gel is milky white and transparent, containing many white small particles( Figure 1 a), which are the hyphae of Rhizopus oryzae; after using the living gel for wastewater treatment, the living gel that adsorbs lignin can be obtained( Figure 1 b), indicating that the living gel can treat sewage. Figure 2 SEM images of the living gel of Rhizopus oryzae nanocellulose and the gel solid waste formed after its use in wastewater treatment. It can be seen from the figure that for the living gel of Rhizopus oryzae nanocellulose( Figure 2 a), there are only sporadic spores of Rhizopus oryzae on the surface. After using it for wastewater treatment for 6 days, lignin begins to aggregate inside the gel( Figure 2 b).

[0066] The COD and BOD contents in the wastewater before and after treatment with the living gel were measured, and the results are as Figure 3 shown. It was found that the living gel has significant sewage treatment ability. The initial COD content of the wastewater was 26388 mg / L. After treatment with the living gel, the COD of the wastewater decreased to 9432 mg / L, and the COD removal rate was as high as 64.3%. At the same time, the BOD 5 content in the wastewater also decreased from 10602 mg / L before treatment to 4780 mg / L after treatment, and the BOD 5 removal rate was as high as 54.9%.

[0067] Characterization of the photothermal conversion ability of the gel solid waste in Example 4

[0068] The gel solid waste that adsorbs lignin in Example 3 was characterized for its photothermal conversion ability.

[0069] 20 μL of laccase (purchased from Aladdin, product number L419514 - 50 ml) was added to 100 mL of the treated wastewater containing 3 - 4 pieces of gel solid waste (obtained in Example 3), and the reaction was carried out at 35 °C and 70 rpm for 12 h to obtain the gel solid waste treated with laccase.

[0070] The living gel of Rhizopus oryzae nanocellulose, the gel solid waste and the gel solid waste treated with the above laccase obtained in Example 3 were subjected to vacuum freeze - drying treatment at - 80 °C for 24 h. Then, the above three gels were irradiated with near - infrared light with a wavelength of 808 nm respectively, and the temperature of the above three gels was monitored simultaneously using the HIKVISION handheld infrared thermometry thermal imager H10. Figure 4Photothermal conversion effect verification experiment photos of Rhizopus oryzae nanocellulose living gel, gel solid waste, and gel solid waste treated with laccase. The experimental results showed that the temperature of the Rhizopus oryzae nanocellulose living gel without adsorbed lignin only rose to 18.7 °C under continuous irradiation of 808 nm near-infrared light; the temperature of the gel solid waste adsorbed with lignin could rise to 101 °C within a short time (10 s) under the irradiation of 808 nm near-infrared light; while after adding laccase, the temperature of the gel solid waste could rise to 190 °C within a short time (less than 10 s) under the irradiation of near-infrared light, which was 90% higher than that of the gel solid waste without laccase treatment. The above experimental results indicate that the photothermal conversion effect of the gel solid waste adsorbed with lignin after treating wastewater of the present invention has been greatly improved compared with the living gel without adsorbed lignin, and the photothermal conversion performance of the gel solid waste treated with laccase is better.

[0071] Example 5 Characterization of the solar evaporation performance of gel solid waste

[0072] Characterize the solar evaporation performance of the laccase-treated lignin-adsorbed gel solid waste in Example 4. The laccase-treated gel solid waste (a cylinder with a bottom radius of 1.2 cm and a height of 2 cm) was subjected to vacuum freeze-drying treatment at -80 °C for 24 h. Place a beaker containing 50 mL of water on an electronic balance (Mettler), put a laccase-treated gel solid waste after freeze-drying treatment into the beaker, use a standard sunlight (fiber optic xenon light source, purchased from Shanghai Hefan Instruments Co., Ltd.) to irradiate the laccase-treated gel solid waste in the beaker, use a HIKVISION handheld infrared thermometry thermal imager H10 to monitor the temperature of the gel in the water, and record the reading of the balance once a minute to calculate the mass change rate of the water in the beaker to characterize the solar evaporation performance of the laccase-treated gel solid waste.

[0073]

[0074] Among them, M t is the mass value shown on the balance when the gel solid waste is irradiated by sunlight for a duration of t, unit: kg;

[0075] M 0 is the mass value shown on the balance when the gel solid waste is not irradiated by sunlight, unit: kg;

[0076] S is the cross-sectional area of the part of the cylindrical gel solid waste irradiated by sunlight. In this example, S = 4.52×10 -4 , unit: m 2 .

[0077] Figure 5Evaporation effect diagram of water by gel solid waste treated with laccase as a solar evaporator. It was experimentally found that the temperature of the gel solid waste in water could rise to 36 °C within 1 hour under sunlight irradiation, and the evaporation effect on water reached 0.7 kg / m 2 .

[0078] The present invention provides an application idea and method of Rhizopus oryzae nanofiber living gel in the treatment of lignocellulosic biorefinery wastewater. There are many methods and ways to specifically implement this technical solution. The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention. Each component not clearly defined in this embodiment can be implemented by existing technologies.

Claims

1. Application of Rhizopus oryzae nanofiber living gel in the treatment of lignocellulose biorefinery wastewater, in, The Rhizopus oryzae nanofiber living gel is prepared by fermenting Rhizopus oryzae, and nanofibers are additionally added to the fermentation medium in the middle and late stages of the fermentation process.

2. The use according to claim 1, characterized in that: The Rhizopus oryzae nanofiber living gel is prepared according to the following method: seed liquid of Rhizopus oryzae is inoculated into a fermentation medium at a volume ratio of 1% to 10%, and fermentation is carried out at a temperature of 30 to 40°C and a certain rotation speed; before the nanofiber is added to the fermentation medium, the rotation speed is 120 to 300 rpm; after the nanofiber is added to the fermentation medium, the rotation speed is 40 to 70 rpm.

3. The use according to claim 1, characterized in that: The additional addition of nanofibers to the fermentation medium in the middle and late stages of the fermentation process is to add the nanofibers to the fermentation medium after 10 to 72 hours of fermentation and continue fermenting for 2 to 20 hours.

4. The use according to claim 1, characterized in that: The nanofiber is any one of nanocellulose, cellulose nanocrystal and chitin nanofiber.

5. The use according to claim 1, characterized in that: The nanofibers are added to the fermentation medium in the form of a nanofiber dispersion; the mass fraction of the nanofibers in the nanofiber dispersion is 0.1% to 2%; the nanofiber dispersion is added to the fermentation medium to obtain a mixed system, and the mass fraction of the nanofibers in the mixed system is controlled to be 0.1% to 1%.

6. The use according to claim 1, characterized in that: The components of the fermentation medium include: 10-40 g / L glucose, 0-1 g / L (NH4)2SO4, 0-1 g / L KH2PO4, 0-0.1 g / L FeSO4, 0.1-1 g / LMgSO4, 0-0.1 g / L ZnSO4, 10-40 g / L CaCO3 and 1-7% v / v citric acid buffer.

7. The use according to claim 1, characterized in that: The lignocellulose is gramineous lignocellulose and / or woody lignocellulose.

8. The use according to claim 1, characterized in that: The method for applying the Rhizopus oryzae nanofiber living gel to the lignocellulose biorefinery wastewater treatment is as follows: adding the Rhizopus oryzae nanofiber living gel to the lignocellulose biorefinery wastewater, and treating it for 1 to 10 days at a temperature of 30 to 40° C. and a stirring speed of 50 to 80 rpm.

9. The use according to claim 1, characterized in that: The lignocellulose biorefining wastewater is treated with the Rhizopus oryzae nanofiber living gel to obtain gel solid waste, which is then reused as a photothermal material.

10. The use according to claim 9, characterized in that: The gel solid waste is reused as photothermal material after being treated with laccase.

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