Method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi

Abstract

The application discloses a method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi, which comprises the following steps: (1) activated carbon pretreatment: screening granular activated carbon, cleaning and drying; (2) loading and adsorption: loading the activated carbon treated in the step (1) in an adsorption column, and feeding antibiotic wastewater into the adsorption column for adsorption; (3) biomass pretreatment: recycling waste biomass, processing the waste biomass into small pieces, and drying the small pieces for standby; (4) inoculation and solid-state fermentation: adding the biomass treated in the step (3) into the activated carbon saturated by adsorption in the step (2), and inoculating white rot fungi for fermentation; and (5) recovery and separation: separating the activated carbon after the fermentation treatment of the fungi. The method can significantly improve the treatment efficiency of the antibiotic wastewater, reduce the wastewater treatment cost, has the characteristics of simplicity, high efficiency, low price and no secondary pollution, and can recycle the regenerated activated carbon after detoxification.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of antibiotic wastewater treatment, and particularly relates to a method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi. BACKGROUND

[0002] Long-term antibiotics in water can cause changes in the genes of microorganisms, leading to enhanced drug resistance of microorganisms, and can have an important impact on drinking water disinfection treatment. Therefore, the control of antibiotic content in the water environment is imminent.

[0003] The commonly used wastewater treatment methods include physical method, chemical method and biological method. On this basis, a new water treatment process combination is researched and explored to improve the removal effect of antibiotics. This is a difficulty in water treatment and a research hotspot worldwide in recent years. Due to the characteristics of antibiotic wastewater such as high toxicity and complex situation, the biological treatment method still relies on adsorption to treat antibiotics. If not properly handled, antibiotics can re-enter the water environment and cause secondary pollution. The advanced oxidation technology has the characteristics of good degradation efficiency, high mineralization rate and less secondary pollution in treating antibiotics. However, the treatment cost is greatly increased in treating low-concentration antibiotic wastewater.

[0004] Adsorption method has the characteristics of low process cost, relatively easy operation and effectiveness. Activated carbon is a multifunctional carrier with adsorption, catalyst and chemical reaction activity, and is widely used in water treatment. It can adsorb substances and trace organic matter with low concentration in water which are difficult to remove by other methods. Researchers such as Adams found that the removal rate of 50 μg / L sulfonamide antibiotic in river water by 10 mg / L PAC was 49% to 73%, and the removal rate of antibiotic reached 65% to 100% when the dosage was increased to 20 mg / L. Wang Jianxing et al. compared the adsorption effect of granular activated carbon on antibiotic wastewater biochemical effluent by static adsorption experiment. The results showed that when the dosage of granular activated carbon was 30 g / L and the adsorption time was 6 h, the treatment effect reached stability.

[0005] Adsorption method has been widely used in the treatment of various types of wastewater. However, single adsorption method can only play an adsorption role in wastewater treatment, and the subsequent treatment is still a key point that needs to be studied. SUMMARY

[0006] Invention purposes: In view of the problems existing in the prior art, the present application provides a method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi. The method uses activated carbon to adsorb antibiotics in wastewater, then adds agricultural waste as a substrate combined with fungi for solid-state fermentation, so as to improve the treatment efficiency of antibiotic wastewater and reduce the cost of wastewater treatment. The method has the characteristics of simplicity, high efficiency, low price and no secondary pollution, and the detoxified regenerated activated carbon can be recycled.

[0007] Technical scheme: In order to achieve the above invention purposes, the technical scheme adopted by the present application is as follows:

[0008] A method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi, comprising the following steps:

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

[0010] (2) Loading and adsorption: loading the activated carbon treated in step (1) into an adsorption column and passing antibiotic wastewater for adsorption;

[0011] (3) Biomass pretreatment: recovering waste biomass, processing into small pieces and drying for standby;

[0012] (4) Inoculation and solid-state fermentation: adding the biomass treated in step (3) to the activated carbon saturated in step (2) and inoculating white rot fungi for fermentation;

[0013] (5) Recovery and separation: separating the activated carbon after fungal fermentation treatment.

[0014] As a specific embodiment, in step (1), the activated carbon pretreatment is sieving activated carbon particles with a particle size of 2 mm or more through a screen, and drying after washing or drying.

[0015] As a specific embodiment, in step (2), the adsorption column is selected from one or more of the following specifications: The loading amount of activated carbon in each adsorption column is 2-17 g; and the effluent flow rate during adsorption is 0.8-1.2 mL / min.

[0016] As a specific embodiment, in step (2), the antibiotics in the antibiotic wastewater include one or a combination of tetracycline, sulfadiazine and norfloxacin; and the concentration of antibiotics in the antibiotic wastewater is 8-12 mg / L.

[0017] As a specific embodiment, in step (3), the biomass is selected from one or a combination of wheat straw, corn straw and peanut shell.

[0018] As a specific embodiment, in step (3), the processing into small pieces is rubbing or cutting the biomass into small pieces or blocks of 1-2 cm.

[0019] As a specific embodiment, in step (4), the white rot fungus is selected from the group consisting of one or several combinations of Pycnoporus sanguineus, Pleurotus ostreatus, Lentinula edodes; and the step before inoculating the white rot fungus further comprises the steps of screening, purifying, and rejuvenating the fungus.

[0020] As a specific embodiment, in step (4), the fermentation further requires adding deionized water, and the mass ratio of the adsorption-saturated activated carbon, the biomass, and the deionized water is 1:(7-9):(7-9); and the fermentation conditions are constant temperature of 25-30℃ and culture for 7-15 days.

[0021] As a specific embodiment, in step (5), the recovery and separation method comprises drying treatment after removing the biomass.

[0022] Advantages: Compared with the prior art, the granular activated carbon is used to make the antibiotics in the wastewater quickly adhere to the inside or surface of the activated carbon by adsorption, which significantly reduces the antibiotic components in the wastewater and greatly improves the removal efficiency of pollutants. Meanwhile, the use of fungal solid-state fermentation to degrade the antibiotics on the adsorption-saturated activated carbon can realize the rapid detoxification of the activated carbon and recycling. Compared with other chemical, physical methods for activated carbon recovery and regeneration, the biological method reduces the use amount of chemical agents, has high fungal fermentation efficiency, good treatment effect, and low cost, and can effectively avoid secondary pollution. Agricultural waste is low in price and widely available, and using agricultural waste as the substrate for fungal solid-state fermentation provides nutrition for the fungal fermentation, which greatly improves the treatment efficiency of pollutants. Therefore, the method for treating low-concentration antibiotic wastewater has the advantages of simplicity, high efficiency, no secondary pollution, low price, recycling of treated activated carbon, and resource recovery of waste biomass. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a tetracycline concentration change graph of a large-dose activated carbon adsorption column;

[0024] Figure 2 is a tetracycline concentration change graph of a small-dose activated carbon adsorption column;

[0025] Figure 3 is the 24h desorption effect of adsorption-saturated activated carbon by different solvents (methanol, ethanol, 5% hydrochloric acid, 10% hydrochloric acid, 20% hydrochloric acid, 30% hydrochloric acid, 40% hydrochloric acid, 50% hydrochloric acid);

[0026] Figure 4 is a process diagram of fungal growth and reproduction on the surface of activated carbon and peanut shells. DETAILED DESCRIPTION

[0027] The present application relates to the technical field of antibiotic wastewater treatment, and specifically relates to a method for degrading and removing antibiotics and detoxifying and regenerating activated carbon by using activated carbon adsorption and solid-state fermentation of fungi on the activated carbon saturated with adsorption and taking agricultural waste as a substrate. The present application relates to the technical field of antibiotic wastewater treatment, and specifically relates to a method for degrading and removing antibiotics and detoxifying and regenerating activated carbon by using activated carbon adsorption and solid-state fermentation of fungi on the activated carbon saturated with adsorption and taking agricultural waste as a substrate.

[0028] The present application selects three typical white rot fungi, which are respectively blood red pore fungus SYBC-L3, pleurotus and lentinus edodes.

[0029] The blood red pore fungus SYBC-L3 is separated from rotten dry wood, and the pleurotus and lentinus edodes are separated from respective fruit bodies.

[0030] The white rot fungi in the present application have the ability to grow by using agricultural waste biomass and antibiotics and other pollutants. Straw, as a substrate for the growth of white rot fungi, provides necessary nutrient elements for the growth of fungi, and can promote the decomposition effect of fungi on antibiotics. The antibiotic wastewater in the present application is selected from wastewater containing tetracycline, sulfadiazine and / or norfloxacin.

[0031] In a representative embodiment, the method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi in the present application comprises the following steps:

[0032] (1) Activated carbon pretreatment: screen the particle activated carbon with a particle size of 2 mm or more by using a 2-mm screen, wash and naturally air dry, and then reserve;

[0033] (2) Activated carbon loading and adsorption of antibiotic wastewater: take 17 g of activated carbon and load into the adsorption column with a size of (2) Activated carbon loading and adsorption of antibiotic wastewater: take 17 g of activated carbon and load into the adsorption column with a size of

[0034] (3) Screening and purifying of P. rhodocarpa, P. duteum and Lentinula edodes: the fungi obtained from natural environment are screened and purified by using PDA medium under the conditions of light avoidance and constant temperature of 30℃;

[0035] (4) Agricultural waste biomass treatment: the wheat straw, peanut shell and corn straw are cut into small pieces with a size of 1-3 cm by using a cutter, and then are naturally dried in the open air for standby;

[0036] (5) Solid state fermentation: the activated carbon saturated by adsorption in (2) is taken out and dried in the shade, and then is mixed with the biomass treated in (4) and deionized water in a ratio of 1:8:8, and is placed in a culture dish, and the fungi in (3) are inoculated on the surface of the activated carbon, and are cultured at a temperature of 30℃ for 7-15 days. The antibiotics adsorbed on the activated carbon are degraded by solid state fermentation and heterotrophic growth of the fungi.

[0037] The inoculation amount of P. rhodocarpa, P. duteum and Lentinula edodes is preferably 1 fungus piece / 3 g solid; the solid state fermentation temperature is 25-30℃, the solid to sterilized water ratio is 1:1-1:1.5, and the fermentation time is 7-15 days.

[0038] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0039] In a representative embodiment, the basic steps of the method of the present application include the following:

[0040] ① Activated carbon pretreatment: screening and washing granular activated carbon, and drying;

[0041] ② Loading and adsorption: the activated carbon treated in step ① is loaded in an adsorption column, and antibiotic wastewater is introduced for adsorption;

[0042] ③ Biomass pretreatment: the waste biomass is recovered, treated into small pieces, and dried for standby;

[0043] ④ Fungal screening, purification and rejuvenation;

[0044] ⑤ Inoculation and solid state fermentation: the biomass treated in step ③ is added to the activated carbon saturated by adsorption in step ②, and white rot fungi are inoculated for fermentation;

[0045] ⑥ Recovery and separation: the activated carbon after fungal fermentation treatment is separated.

[0046] Example 1

[0047] The separation and screening was carried out by using tissue blotting method, and the separation and screening method was as follows: rotten wood, Pleurotus ostreatus fruiting body, Lentinula edodes fruiting body were taken into a beaker and soaked with sterile water for 2 hours. Then the liquid sample was diluted into different gradients and coated on PDA (20% potato extract, 2% glucose, 2% agar) medium containing 4% 2,6-dimethoxybenzene. The growth of colonies on the medium and whether there was a red discoloration ring around the colonies was observed every day, and the strains with a red discoloration ring around the colonies were selected and transferred to new PDA medium, and finally the purified strains were obtained. The purified strains were inoculated on PDA slant and stored in a refrigerator at 4°C for subsequent use.

[0048] In order to restore the activity of fungi in low-temperature storage state, the fungi need to be rejuvenated and cultured, and the specific process is as follows: under sterile operation, the low-temperature preserved strains were placed in PDA medium and incubated at 30°C for 8-12 hours, and then the pure and strong culture was obtained by step-by-step expansion, that is, the fungi with vigorous activity and sufficient inoculation quantity were obtained.

[0049] Example 2

[0050] The active carbon was used to adsorb low-concentration antibiotics, and the adsorption efficiency could reach more than 90%, the adsorption capacity was strong, and the service time was long. On this basis, the growth and metabolism of fungi could degrade the adsorbed pollutants, so that the detoxification and recycling of active carbon could be realized, the effective removal of pollutants in wastewater could be truly realized, no secondary pollution was produced, and it was green, environmental protection and low carbon.

[0051] Large-dose active carbon continuous adsorption test steps: 17g of active carbon was filled into an adsorption column with a size of The water inlet antibiotic concentration was set to 10mg / L, the water outlet flow rate was 1mL / min, and the continuous water inlet and outlet were carried out under the conditions of natural pH and room temperature until saturation.

[0052] Small-dose active carbon continuous adsorption test steps: 2g of active carbon was filled into an adsorption column with a size of The water inlet antibiotic concentration was set to 10mg / L, the water outlet flow rate was 1mL / min, and the continuous water inlet and outlet were carried out under the conditions of natural pH and room temperature until saturation.

[0053] As shown in Figure 1 , the large-dose active carbon continuously adsorbed tetracycline, and the three adsorption columns reached adsorption equilibrium at about 948h, and the outlet tetracycline was 6.0-6.3mg / L. As shown in Figure 2The activated carbon was used to continuously adsorb tetracycline at a low dose, reaching adsorption equilibrium in approximately 168 hours, with the effluent tetracycline concentration at 8.4-8.5 mg / L. The maximum adsorption capacity of activated carbon for tetracycline was approximately 18.6335 mg / L.

[0054] Example 3

[0055] To better investigate the effect of subsequent fungal growth and fermentation on tetracycline degradation, it is necessary to explore the optimal desorption efficiency of activated carbon. 100 mL of solvents were added to shake flasks, including methanol, ethanol, 5% hydrochloric acid, 10% hydrochloric acid, 20% hydrochloric acid, 30% hydrochloric acid, 40% hydrochloric acid, and 50% hydrochloric acid. 5 g of saturated activated carbon was added to each solvent, and the flasks were shaken and reacted at ambient pH and room temperature for 24-48 h. After the reaction was complete, the transmittance of the solvent after reaction was measured at 320 nm using a UV-Vis spectrophotometer. The tetracycline content in the desorbed solvent was calculated using a fitted standard curve, and the desorption efficiency of different solvents for tetracycline on activated carbon was calculated using the following formula:

[0056] C0—Maximum adsorption capacity of granular activated carbon for tetracycline, mg / g;

[0057] C e —Tetracycline desorption amount over 24h / 48h, mg / g.

[0058] like Figure 3 The figure shows the desorption effect of different solvents on saturated activated carbon after 24 hours. 30% hydrochloric acid showed a significant effect on the desorption of tetracycline from activated carbon, achieving a desorption amount of 10.658 mg / g and a desorption efficiency of 57.2% after 24 hours. Further reaction for 48 hours resulted in a tetracycline desorption amount of 17.1056 mg / g with 30% hydrochloric acid, achieving a desorption efficiency of 91.8%. Therefore, 30% hydrochloric acid is a better solvent for tetracycline desorption.

[0059] Example 4

[0060] (1) Activated carbon pretreatment: Use a 2mm sieve to screen out granular activated carbon with a particle size of more than 2mm, wash it and let it air dry for later use.

[0061] (2) Activated carbon filling and adsorption of antibiotic wastewater: Take 2g of activated carbon and fill it into containers of a size of [size missing]. In the adsorption column, the influent antibiotic concentration was set to 10 mg / L (the antibiotic was tetracycline), the effluent flow rate was 1 mL / min, and the influent and effluent were continuously fed and discharged. The adsorption was carried out until saturation under natural pH and room temperature conditions.

[0062] (3) Peanut shell pretreatment steps are as follows: cut or crush the peanut shells into small pieces of 1-2cm and air dry them outdoors for later use.

[0063] (4) Screening and purification of P. coccineus: Screening, purification and rejuvenation were carried out according to the method of Example 1 above.

[0064] (5) Inoculation and solid state fermentation: After the granular activated carbon was saturated in the dynamic adsorption test, the activated carbon was taken out and dried in the shade. The saturated granular activated carbon and the biomass were sterilized, mixed with deionized water in a ratio of 1:8:8, and placed in a culture dish. The P. coccineus activated on the PDA plate was inoculated on the surface of the saturated activated carbon (inoculation amount: 1 piece of fungus per 3 g of solid), and solid state fermentation was carried out at a temperature of 25-30°C for 15 days. Figure 4 for the growth and reproduction of fungi on the surface of activated carbon and peanut shells.

[0065] The present technology is based on solid state fermentation technology, which comprehensively utilizes the adsorption of activated carbon on antibiotic wastewater, uses agricultural waste straw as substrate, and uses solid state fermentation technology of fungi to treat antibiotic wastewater, so as to ultimately achieve the removal of antibiotics and the detoxification and regeneration of activated carbon.

[0066] The saturated granular activated carbon and the activated carbon treated by fungi were separated and sterilized, and then desorption test was carried out with 30% hydrochloric acid. After the reaction was completed, the solvent after reaction was taken out, and the transmittance was measured at a wavelength of 320 nm by ultraviolet-visible spectrophotometer. The content of tetracycline in the desorbed solvent was calculated by the standard curve, and the treatment efficiency of fungi fermentation on tetracycline on activated carbon was calculated by the following formula:

[0067]

[0068] Q0— The maximum desorption amount of tetracycline of the saturated granular activated carbon, mg / g;

[0069] Q e — The maximum desorption amount of tetracycline of the granular activated carbon after fungi fermentation, mg / g.

[0070] As shown in Table 1, the solid state fermentation efficiency of three kinds of antibiotics (antibiotic wastewater containing sulfadiazine and norfloxacin was also treated in the same way). The results showed that the treatment efficiency of fungi fermentation on activated carbon adsorbed antibiotics could reach more than 85%, among which the treatment efficiency of tetracycline was the best, which could reach 94%. It was analyzed that the most effective component of fungi for degrading tetracycline wastewater was laccase, which was a new type of green biological catalyst, and had wide application in dye wastewater treatment, soil remediation, food processing, biological pharmacy, chemical synthesis, cloth dyeing and decolorization, biofuel, etc.

[0071] Table 1: Solid state fermentation treatment efficiency of three kinds of antibiotics

[0072] Tetracycline Sulfadiazine Norfloxacin Adsorption capacity of activated carbon (mg / g) 18.6335 25.2147 18.5134 Remaining amount after solid state fermentation treatment (mg / g) 1.0860 3.5030 2.1120 Efficiency of solid state fermentation treatment (%) 94.17 86.11 88.59

[0073] The embodiments of the present application are described in detail above with reference to the accompanying drawings and specific embodiments, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

Claims

1. A method for treating low concentration antibiotic wastewater by using activated carbon combined with fungi, characterized in that, The method comprises the following steps: (1) Activated carbon pretreatment: screening activated carbon particles, cleaning and drying; (2) Loading and adsorption: loading the activated carbon treated in step (1) in an adsorption column, and passing in antibiotic wastewater for adsorption; the antibiotics in the antibiotic wastewater include one or a combination of several of tetracycline, sulfadiazine and norfloxacin; (3) Biomass pretreatment: recycling waste biomass, treating into small pieces, and drying for standby; the biomass is selected from one or a combination of several of wheat straw, corn straw and peanut shell; (4) Inoculation and solid-state fermentation: adding the biomass treated in step (3) to the activated carbon saturated in step (2), and inoculating white rot fungi for fermentation; deionized water is also needed to be added, and the mass ratio of the adsorption-saturated activated carbon, biomass and deionized water is 1: (7-9): (7-9); the fermentation conditions are constant temperature of 25-30 DEG C, and culture for 7-15 days; the white rot fungi are selected from one or a combination of several of Laetiporus, Pleurotus and Lentinus edodes; (5) Recovery and separation: separating out the activated carbon after fungal fermentation treatment.

2. The method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (1), the activated carbon pretreatment is to screen out activated carbon particles with particle size of 2 mm or more through a screen, and then dry after cleaning.

3. The method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (2), the adsorption column is selected from one or several of the following specifications: 16*400 mm, 20*400 mm and 35*400 mm, and the loading amount of activated carbon in each adsorption column is 2-17 g; when adsorption is performed, the effluent flow rate is 0.8-1.2 mL / min.

4. The method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (2), the concentration of antibiotics in the antibiotic wastewater is 8-12 mg / L.

5. The method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (3), the treatment into small pieces is to knead or cut the biomass into small pieces or blocks of 1-2 cm.

6. The method for treating low concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (4), the inoculation of white rot fungi further comprises the steps of fungus screening, purification and rejuvenation before inoculation.

7. The method for treating low-concentration antibiotic wastewater by using activated carbon combined with fungi according to claim 1, characterized in that, In step (5), the recovery and separation method comprises drying treatment after removing the biomass.

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