A method for treating antibiotic wastewater by enhanced fungal solid-state fermentation

Abstract

The present invention discloses a method for treating antibiotic wastewater by strengthening fungal solid-state fermentation, comprising the following steps: (1) activated carbon pretreatment: screening granular activated carbon, washing, and drying; (2) biomass pretreatment: drying the biomass and forming small segments or blocks; (3) biomass modification: placing the obtained biomass in an amino acid solution, reacting under the action of an esterification reagent, cooling, washing, and drying to obtain modified biomass; (4) adsorption: mixing the activated carbon obtained in step (1), the modified biomass obtained in step (3), and antibiotic wastewater, stirring and adsorbing to obtain adsorption-saturated activated carbon and modified biomass; (5) inoculation and microbial culture degradation: adding soybean meal to the adsorption-saturated activated carbon and modified biomass in step (4), and inoculating white rot fungi or microalgae for cultivation; and (6) recovery and separation: separating the activated carbon after fungal fermentation treatment. The method is simple and efficient, has high adsorption efficiency, a wide range of substrate sources, and low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of antibiotic wastewater treatment, and particularly relates to a method for treating antibiotic wastewater by enhanced fungal solid-state fermentation. Background Art

[0002] Antibiotic wastewater primarily originates from wastewater from the production of traditional Chinese medicines and synthetic pharmaceuticals. The four stages of the antibiotic production process, namely fermentation, extraction, refining, and final product development, produce highly concentrated, recalcitrant toxic substances. These substances inhibit the activity of microorganisms during the biochemical treatment of the wastewater, making them difficult to degrade. When antibiotic wastewater enters the environment, it can induce the development of drug-resistant microorganisms, disrupt the composition of microbial populations, and affect the operation and effectiveness of municipal wastewater biochemical treatment processes, significantly impacting human health, ecological balance, and environmental pollution.

[0003] Adsorption is a method of purifying wastewater by removing specific pollutants from it through adsorption and recovery using adsorbents. Commonly used adsorbents include activated carbon, slag, and resins. While adsorption requires minimal equipment, achieving good adsorption results with the addition of suitable adsorbents is possible. However, there are also issues such as difficulty in reusing the adsorbent.

[0004] Xu Shuqing studied the treatment effects of adsorption materials such as waste slag and activated carbon on pharmaceutical wastewater. The study showed that activated carbon was more effective than slag in COD degradation, achieving a 95.7% COD degradation rate, and was also effective in treating ammonia nitrogen and total phosphorus. Wu Qinyue et al. produced biochar from pyrolysis of pharmaceutical sludge. At a biochar dosage of 50 g / L, adsorption for one hour achieved 66.3% COD removal and 61.8% adsorbable organic halogens (AOX). Multi-stage adsorption also achieved even better results at lower dosages.

[0005] Adsorption method is widely used in treating various types of sewage, but a single adsorption method can only play an adsorption role in treating wastewater. Subsequent treatment is still a focus that needs to be studied, and there is also the problem of poor adsorption effect. Summary of the Invention

[0006] Purpose of the Invention: To address the challenges of existing technologies, the present invention proposes a method for treating antibiotic wastewater using enhanced fungal solid-state fermentation. This method utilizes agricultural waste and agricultural byproducts as substrates, combined with fungal solid-state fermentation, to detoxify and regenerate activated carbon, thereby reducing wastewater treatment costs. The activated carbon detoxification and regeneration method of the present invention is simple, efficient, has a wide range of substrate sources, and is inexpensive.

[0007] Technical solution: In order to achieve the above-mentioned purpose of the invention, the technical solution adopted by the present invention is as follows:

[0008] A method for treating antibiotic wastewater by enhanced fungal solid-state fermentation comprises the following steps:

[0009] (1) Activated carbon pretreatment: screening granular activated carbon, washing, and drying;

[0010] (2) Biomass pretreatment: drying the biomass and making it into small segments or blocks;

[0011] (3) Biomass modification: placing the obtained biomass in an amino acid solution, reacting under the action of an esterification reagent, cooling, washing, and drying to obtain modified biomass;

[0012] (4) Adsorption: mixing the activated carbon obtained in step (1), the modified biomass obtained in step (3), and the antibiotic wastewater, stirring and adsorbing, and obtaining adsorption-saturated activated carbon and modified biomass;

[0013] (5) Inoculation and microbial culture degradation: adding soybean meal to the activated carbon and modified biomass saturated with adsorption in step (4), and inoculating white rot fungi or microalgae for culture;

[0014] (6) Recovery and separation: Separate the activated carbon after fungal fermentation.

[0015] As a specific implementation scheme, in step (1), the activated carbon pretreatment is to screen out activated carbon particles with a particle size of 2 mm or more through a sieve, and then dry or bake them after washing.

[0016] As a specific implementation scheme, in step (2), the biomass is selected from one or more of peanut shells, corn straw or wheat straw; the small segments or blocks are 1-2 cm small segments or blocks, which are made by crushing, rolling or cutting.

[0017] As a specific implementation scheme, in step (3), the mass ratio of the biomass to the amino acid is (2-3):1; the concentration of the amino acid solution is 90-110 mg / L, the pH is adjusted to 8-9, and esterification reagents ethanol, concentrated sulfuric acid and acetic acid are added, and the reaction is carried out for 45-50 hours.

[0018] As a specific implementation scheme, in step (4), the antibiotic in the antibiotic wastewater is one or more of tetracycline, sulfadiazine, and norfloxacin; and the concentration of the antibiotic in the antibiotic wastewater is 0.5-1.5 g / L.

[0019] As a specific implementation scheme, in step (4), the addition amount of the modified biomass is 1-20 g / L antibiotic wastewater, the addition mass ratio of activated carbon and modified biomass is (20-30): (15-25); the stirring rate of the stirring adsorption is 50-70 r / min.

[0020] As a specific implementation scheme, in step (5), the soybean meal is dry soybean meal and is made into small pieces of 1-2 cm; the white rot fungus is selected from one or a combination of Pycnopsis sanguinosa, Pleurotus ostreatus, and Lentinus edodes; and before the inoculation of white rot fungi, the process also includes the steps of fungus screening, purification, and rejuvenation.

[0021] As a specific implementation scheme, in step (5), taking the amount of adsorption-saturated modified biomass as a reference, the mass ratio of adsorption-saturated modified biomass to soybean meal is 1:(0.8-1.2); the culture also requires the addition of deionized water, and the mass ratio of soybean meal to deionized water is 1:(1.8-2.2).

[0022] As a specific implementation scheme, in step (5), the culture conditions are: constant temperature 25-30°C, and culture for 5-10 days.

[0023] As a specific embodiment, in step (5), the recovery and separation method includes removing the biomass and soybean meal and then performing a drying process.

[0024] Beneficial effects: Compared with the prior art, the present invention has the following advantages:

[0025] (1) Biomass, such as peanut shells, contains a large number of hydroxyl groups in its cellulose structure, which can undergo esterification reactions with the carboxyl groups in amino acids. Amino acids can also undergo self-polymerization, and the resulting polymers can play a role in supporting pores. The presence of ester groups can more firmly adsorb antibiotic molecules, while amino groups can provide an energy source for bacterial fermentation. The presence of these three structures synergistically improves the adsorption and degradation effect of the biomass-activated carbon-fungus system on antibiotics.

[0026] (2) Soybean meal is rich in nutrients such as lactic acid, vitamins, and amino acids, which can provide energy for the growth and fermentation of fungi. It also contains a variety of microbial enzymes such as protease, amylase, lipase, etc., which can promote and accelerate the solid-state fermentation process of fungi.

[0027] (3) Peanut shells and soybean meal are agricultural by-products and can be recycled and reused in water treatment to achieve the goal of “treating waste with waste”.

[0028] (4) Activated carbon adsorption and biomass adsorption are coupled with fungal solid-state fermentation to treat antibiotic wastewater. Fungi are used to harmlessly regenerate activated carbon that adsorbs pollutants to avoid secondary pollution. The substrate source is wide, the cost is low, and the treatment effect is good. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a flow chart of the method of the present invention;

[0030] Figure 2The 24h desorption effect of different solvents on adsorption saturated activated carbon (methanol, ethanol, 5% hydrochloric acid, 10% hydrochloric acid, 20% hydrochloric acid, 30% hydrochloric acid, 40% hydrochloric acid, 50% hydrochloric acid). DETAILED DESCRIPTION

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0032] like Figure 1 The flow chart of the method of the present invention is shown. The present invention relates to the technical field of antibiotic wastewater treatment, specifically a method for degrading and removing antibiotics and detoxifying activated carbon by coupling activated carbon and biomass adsorption with fungal solid-state fermentation. The basic steps of the method of the present invention include the following:

[0033] ① Activated carbon pretreatment: screening granular activated carbon, cleaning and drying;

[0034] ② Biomass processing: dry the biomass naturally, crush and sieve it, and then dry it for later use;

[0035] ③ Biomass modification: placing the biomass in an amino acid solution, reacting it under the action of an esterification reagent, cooling, washing, and drying it to obtain modified biomass;

[0036] ④Filling and adsorption: Place the activated carbon and biomass treated in steps ① and ③ in a beaker, add antibiotic wastewater and stir for adsorption;

[0037] ⑤Fungus screening, purification, and rejuvenation;

[0038] ⑥ Inoculation and solid-state fermentation: soybean meal is added to the activated carbon and biomass saturated with adsorption in step ④, and white rot fungi are inoculated for fermentation;

[0039] ⑦ Recovery and separation: Separate the activated carbon after fungal fermentation treatment.

[0040] This technology is based on solid-state fermentation technology, which comprehensively utilizes the adsorption effect of activated carbon and biomass on antibiotic wastewater. It uses biomass as substrate and agricultural by-product soybean meal as an external nitrogen source, and utilizes fungal solid-state fermentation technology to treat antibiotic wastewater, ultimately achieving the removal of antibiotics and the detoxification and regeneration of activated carbon.

[0041] The present invention selects three typical white rot fungi, namely, Pycnopsis sanguineus SYBC-L3, Pleurotus ostreatus and Lentinula edodes.

[0042] Pycnopsis sanguinea SYBC-L3 was isolated from rotten dry wood, and Pleurotus ostreatus and Lentinus edodes were purified strains isolated from their respective fruiting bodies.

[0043] The white-rot fungi of the present invention have the ability to utilize biomass and pollutants such as antibiotics for growth. Biomass such as peanut shells, as agricultural waste, is inherently rich in cellulose. After modification, its pores are supported by polymers, enabling more robust adsorption of antibiotic molecules. The amino groups also provide an energy source for the fermentation of the bacteria, promoting fungal fermentation. Soybean meal, as an agricultural byproduct, is rich in nutrients such as lactic acid, microorganisms, and amino acids, which also provide energy for fungal growth and fermentation. Adding it as a nitrogen source can significantly shorten the fermentation cycle and promote the fungal decomposition of antibiotics. The antibiotic wastewater described in the present invention is wastewater containing tetracycline.

[0044] Example 1

[0045] Isolation and screening were performed using the tissue blotting method. The following method was used: rotten wood, oyster mushroom fruiting bodies, and shiitake mushroom fruiting bodies were placed in a beaker and soaked in sterile water for 2 hours. The liquid sample was then diluted into different gradients and spread onto PDA (20% potato extract, 2% glucose, 2% agar) medium containing 4% 2,6-dimethoxybenzene. The growth of the colonies on the medium was observed daily, as well as the presence of red discoloration zones around the colonies. Strains with red discoloration zones were selected and transferred to fresh PDA medium to obtain purified strains. The purified strains were inoculated onto PDA slants and stored in a refrigerator at 4°C for subsequent use.

[0046] In order to restore the activity of fungi stored at low temperature, the fungi need to be rejuvenated and cultured. The specific process is as follows: under sterile operation, the low-temperature stored strains are placed in PDA culture medium and then cultured at a constant temperature of 30°C for 8-12 hours. The culture is expanded step by step to obtain a pure and strong culture, that is, a fungus with vigorous activity and sufficient inoculation quantity.

[0047] Example 2

[0048] In order to better explore the effect of subsequent fungal growth and fermentation on tetracycline degradation, it is necessary to explore the optimal activated carbon desorption efficiency. Add 100mL of solvents into the shaking flask, namely methanol, ethanol, 5% hydrochloric acid, 10% hydrochloric acid, 20% hydrochloric acid, 30% hydrochloric acid, 40% hydrochloric acid, and 50% hydrochloric acid, add 5g of adsorption-saturated activated carbon to each solvent, put it into the shaker for shaking, and react for 24-48h at natural pH and room temperature. After the reaction is completed, remove the solvent after the reaction and measure the transmittance at a wavelength of 320nm with a UV-visible spectrophotometer. Calculate the content of tetracycline in the desorbed solvent by fitting the standard curve, and calculate the desorption efficiency of tetracycline on activated carbon by different solvents by the following formula:

[0049]

[0050] C0——maximum adsorption capacity of granular activated carbon for tetracycline, mg / g;

[0051] C e ——Tetracycline desorption amount in 24h / 48h, mg / g.

[0052] like Figure 2 The figure shows the 24-hour desorption effects of different solvents on adsorbed activated carbon. 30% hydrochloric acid showed a significant effect on the desorption of tetracycline from activated carbon, achieving a 24-hour desorption rate of 32.51 mg / g and a desorption efficiency of 56.2%. Furthermore, after continuing the reaction for 48 hours, 30% hydrochloric acid desorbed 52.76 mg / g of tetracycline, achieving a desorption efficiency of 91.2%. Therefore, 30% hydrochloric acid is a preferred solvent for tetracycline desorption.

[0053] Example 3

[0054] (1) Activated carbon pretreatment: screen out activated carbon larger than 2 mm, wash and dry;

[0055] (2) Biomass pretreatment: Crush or cut the peanut shells into 1-2 cm segments or pieces, sieve them, and dry them for later use.

[0056] (3) Biomass modification: The dried peanut shells were soaked in a 100 mg / L amino acid solution, wherein the mass ratio of biomass to amino acid was 2:1, and the pH was adjusted to 8-9. Ethanol, concentrated sulfuric acid, and acetic acid solutions were added to carry out esterification reaction for 48 h. The modified peanut shells were obtained after washing and drying.

[0057] (4) Adsorption: 25 g of the prepared activated carbon and 20 g of modified peanut shells were added to 10 L of 1 g / L antibiotic wastewater (containing tetracycline) for adsorption at a stirring rate of 60 r / min. After the granular activated carbon and the peanut shells were saturated with adsorption in the static adsorption test, they were removed and dried in the shade for later use.

[0058] (5) Inoculation and microbial culture degradation: After sterilizing the activated carbon, modified peanut shells, and soybean meal, the adsorption-saturated activated carbon, modified peanut shells, soybean meal, and deionized water were mixed evenly in a ratio of 2.5:2:2:4 and placed in a culture dish. The activated P. sanguineus cultured on the PDA plate was inoculated in the culture dish (inoculation amount was 1 bacterial plate / 3 g solid), and solid-state fermentation was carried out at a temperature of 25-30°C for 8 days.

[0059] (6) Recovery and separation: After removing peanut shells and soybean meal from the mixture after fungal treatment, the mixture was separated and treated with activated carbon. After drying and sterilization, a desorption test was performed using 30% hydrochloric acid. After the reaction was completed, the solvent after reaction was removed and the transmittance was measured at a wavelength of 320 nm using a UV-visible spectrophotometer. The content of tetracycline in the solvent after desorption was calculated using the fitted standard curve, and the treatment efficiency of tetracycline on activated carbon by fungal fermentation was calculated using the following formula:

[0060]

[0061] Q0——maximum desorption capacity of tetracycline on adsorption-saturated granular activated carbon, mg / g;

[0062] Q e ——The maximum desorption amount of tetracycline by granular activated carbon after fungal fermentation, mg / g.

[0063] Fungal fermentation can achieve a treatment efficiency of over 96% for tetracycline adsorbed on activated carbon. Analysis has shown that the most effective fungal component capable of degrading tetracycline wastewater is laccase, a novel green biocatalyst with a wide range of applications in dye wastewater treatment, soil remediation, food processing, biopharmaceuticals, chemical synthesis, cloth dyeing and bleaching, and biofuels.

[0064] Table 1 Antibiotic solid-state fermentation treatment efficiency of Example 3

[0065] tetracycline Activated carbon adsorption capacity (mg / g) 57.85 Residual amount after solid-state fermentation treatment (mg / g) 1.86 Solid-state fermentation treatment efficiency (%) 96.8

[0066] Table 2 Residual concentration of tetracycline adsorbed by different methods

[0067]

[0068] The comparative example is basically the same as Example 3, except that the biomass is not subjected to amino acid modification (ie, there is no treatment process in step 3) and is directly used for adsorption of antibiotics.

[0069] As shown in Table 2, after saturated adsorption, the concentration of tetracycline remaining in the wastewater after saturated adsorption was significantly lower when the biomass was modified with amino acids, compared to biomass without amino acid modification. Therefore, the adsorption of antibiotics by the biomass modified with amino acids is significantly enhanced.

[0070] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings and specific embodiments. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

[0071] The above describes the implementation mode of the present invention in detail with reference to the accompanying drawings and specific embodiments. However, the present invention is not limited to the above implementation mode. Various changes can be made within the scope of knowledge possessed by ordinary technicians in the relevant technical field without departing from the purpose of the present invention.

Claims

1. A method for treating antibiotic wastewater by enhanced fungal solid-state fermentation, characterized in that: The following steps are involved: (1) Activated carbon pretreatment: screening granular activated carbon, washing, and drying; (2) Biomass pretreatment: drying the biomass and forming it into small pieces; the biomass is selected from one or more of peanut shells, corn straw or wheat straw; (3) Biomass modification: placing the obtained biomass in an amino acid solution, reacting it under the action of an esterification reagent, cooling, washing, and drying it to obtain modified biomass; The esterification reagents are ethanol, concentrated sulfuric acid and acetic acid; (4) Adsorption: The activated carbon obtained in step (1), the modified biomass obtained in step (3) and the antibiotic wastewater are mixed, stirred and adsorbed to obtain adsorption-saturated activated carbon and modified biomass; (5) Inoculation and microbial culture degradation: soybean meal is added to the activated carbon and modified biomass saturated with adsorption in step (4), and white rot fungi are inoculated and cultured; the white rot fungi are selected from one or a combination of Pyricularia sanguinosa, Pleurotus ostreatus, and Lentinus edodes; (6) Recovery and separation: Separate the activated carbon after fungal fermentation.

2. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (1), the activated carbon pretreatment is to screen out activated carbon particles with a particle size of 2 mm or more through a sieve, and then dry or bake them after washing.

3. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (2), the small segments are 1-2 cm segments, which are made by crushing, rolling or cutting.

4. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (3), the mass ratio of the biomass to the amino acid is (2-3):1; the concentration of the amino acid solution is 90-110 mg / L, the pH is adjusted to 8-9, and an esterification reagent is added to react for 45-50 hours.

5. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (4), the antibiotic in the antibiotic wastewater is one or more of tetracycline, sulfadiazine, and norfloxacin; and the concentration of the antibiotic in the antibiotic wastewater is 0.5-1.5 g / L.

6. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (4), the dosage of the modified biomass is 1-20 g / L antibiotic wastewater, the addition mass ratio of activated carbon to modified biomass is (20-30): (15-25); and the stirring rate of the stirring adsorption is 50-70 r / min.

7. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (5), the soybean meal is dried soybean meal and is made into small pieces of 1-2 cm; and before the inoculation of white rot fungi, the steps of fungus screening, purification, and rejuvenation are also included.

8. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (5), the amount of the adsorption-saturated modified biomass is used as a reference, and the mass ratio of the adsorption-saturated modified biomass to the soybean meal is 1: (0.8-1.2); the culture also requires the addition of deionized water, and the mass ratio of the soybean meal to the deionized water is 1: (1.8-2.2).

9. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (5), the culture conditions are: constant temperature 25-30°C, and culture for 5-10 days.

10. The method for treating antibiotic wastewater by enhanced fungal solid-state fermentation according to claim 1, characterized in that: In step (6), the recovery and separation method includes removing the biomass and soybean meal and then performing a drying process.

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