Sewage treatment method based on silicon-based supported phenol oxidase catalyst

Abstract

The invention belongs to the technical field of sewage treatment, and discloses a sewage treatment method based on a silicon-based supported phenol oxidase catalyst. The method comprises the following steps: firstly, preparing a silicon-based supported phenol oxidase catalyst, carrying out acid pickling and 3-azidopropyltrimethoxysilane modification on a nano flaky silicon dioxide carrier, carrying out a click chemical reaction on the nano flaky silicon dioxide carrier and alkyne ortho-dithiopyridine, introducing an ortho-dithiopyridine group on the surface of the carrier, and further covalently immobilizing phenol oxidase through a disulfide bond, so as to obtain the silicon-based supported phenol oxidase catalyst. The catalyst with high stability and high loading capacity is prepared. When the catalyst is used for treating phenol-ammonia wastewater, the wastewater is firstly subjected to oil removal, deacidification and ammonia distillation pretreatment; then catalyzing phenolic substances in the wastewater to be subjected to oxidative polycondensation by utilizing a catalyst under a weak acid condition, so as to form easily separated polyphenol flocculent substances; after precipitation separation, carrying out deep catalytic polycondensation on supernate through an electrochemical reactor; and finally, biochemical treatment is performed through a synchronous nitrification and denitrification process, so that up-to-standard discharge of the wastewater is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a sewage treatment method based on a silicon-based loaded phenol oxidase catalyst. BACKGROUND

[0002] Phenol-ammonia wastewater is mainly generated in low-temperature pyrolysis in the field of coal chemical industry, such as low-rank coal pyrolysis utilization, production of semi-coke, and production process of Lurgi furnace. The wastewater has complex composition and contains a large amount of non-degradable and highly toxic pollutants, such as benzene series, phenols, polycyclic aromatic hydrocarbons, nitrogen-oxygen heterocyclic compounds, and inorganic pollutants such as heavy metals, and is a typical high-pollution and high-toxicity industrial wastewater. The phenol-ammonia wastewater mainly has the following characteristics:

[0003] (1) The wastewater contains a large amount of oil, in addition to heavy oil mainly composed of polycyclic aromatic hydrocarbons and light oil mainly composed of straight-chain hydrocarbons, and also contains a large amount of emulsified oil.

[0004] (2) The wastewater contains high-concentration phenols and a certain concentration of cyanide pollutants. These two pollutants have biological toxicity and can cause protein coagulation, and have toxic effects on water treatment microorganisms.

[0005] (3) Poor biodegradability. In addition to phenolic substances, the organic matter in semi-coke wastewater mainly includes coal tar substances, polycyclic aromatic compounds, and nitrogen, oxygen, and sulfur-containing heterocyclic compounds, which have the characteristics of high toxicity and difficult degradation. After phenol removal, the B / C is about 0.1-0.16.

[0006] (4) The ammonia nitrogen concentration in the wastewater is high.

[0007] (5) The wastewater has high colority. Due to the presence of various color-forming groups and auxiliary color groups in semi-coke wastewater, the colority of the wastewater can reach tens of thousands of times.

[0008] For this wastewater, direct biochemical treatment is difficult to operate normally and cannot meet the discharge standard. Different pollutants in the wastewater need to be treated by multiple process combinations. Traditionally, for this type of wastewater, the ammonia evaporation-extraction-phenol removal-high-level oxidation-biochemical treatment process is used. However, this process has the disadvantages of high construction cost, high operating cost, and poor quality of by-product crude phenol. At the same time, the ammonia evaporation-extraction-phenol removal process is a high-risk process with flammability and explosiveness, and requires high operating personnel. At the same time, the process is unstable and easy to cause fluctuations in the effluent quality. In view of the problems existing in the current process, relevant scientific research units and enterprises have also explored the use of formaldehyde to generate phenolic resin with phenolic substances in the wastewater to achieve the purpose of phenol removal, but this process also has the defects of flammability, explosiveness, and toxicity, and there is no successful case. How to clean, efficiently, safely, and at low cost treat this type of wastewater is a problem that needs to be solved urgently. SUMMARY

[0009] In view of the above, in order to overcome the defects of the prior art, the application discloses a silicon-based supported phenol oxidase catalyst and a wastewater treatment method based on the silicon-based supported phenol oxidase catalyst.

[0010] In order to achieve the above-mentioned purpose, the following technical scheme is adopted: on the one hand, the application provides a silicon-based supported phenol oxidase catalyst, and the preparation process thereof comprises the following steps:

[0011] (1) carrier pretreatment: taking a nanosheet-shaped silica carrier, performing acid washing, vacuum filtration, pure water leaching to neutral, and drying to obtain a pure and dry nanosheet-shaped silica carrier;

[0012] (2) carrier modification: dispersing 1.0 g of the dry nanosheet-shaped silica carrier in 50-80 mL of anhydrous toluene, ultrasonic treatment for 30 min, adding 0.48-0.6 mL of 3-azidopropyltrimethoxysilane dropwise under the protection of inert gas, heating to 80-90 DEG C, centrifugal separation of the product, and sequentially washing with toluene and drying to obtain azidated silica;

[0013] dissolving 0.84-1 mL of propargyl acid in 60-100 mL of anhydrous DMF, sequentially adding 1.5-2.0 g of N-hydroxysuccinimide and 2.75-2.88 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride under ice bath, activating for 4-6 h, dissolving 2.3-2.6 g of 2-pyridine dithioethylamine hydrochloride and 2.8-3.2 mL of triethylamine in 50-60 mL of anhydrous DMF, adding dropwise to the activated solution, reacting for 2 h at room temperature and in dark, and purifying through a chromatographic column to obtain alkyne-alkyne pyridine disulfide;

[0014] dispersing 2.0-4.0 g of the azidated silica in 80-100 mL of a mixed solvent of deionized water and tert-butyl alcohol with a volume ratio of 1:1, adding 0.42-0.5 g of the alkyne-alkyne pyridine disulfide, sequentially adding 0.01-0.016 g of sodium ascorbate and 0.01-0.02 g of copper sulfate pentahydrate, reacting for 12-24 h under the protection of inert gas, centrifugal collection of the solid product, washing with EDTA solution and deionized water alternately, and vacuum drying to obtain modified nanosilica with a pyridine disulfide group on the surface;

[0015] (3) enzyme liquid treatment: performing concentration treatment on a phenol oxidase extract produced by biological fermentation;

[0016] (4) loading and adsorption: adding the concentrated phenol oxidase extract dropwise into the pure and dry modified nanosilica carrier according to a set enzyme activity ratio, stirring to make the enzyme liquid and the carrier fully contact, and then standing and adsorbing;

[0017] (5) Cleaning and purification: The loaded carrier is cleaned multiple times with pH buffer solution to remove unadsorbed enzymes and impurities, and silicon-based supported phenol oxidase catalyst is obtained.

[0018] Furthermore, in step (1), the nanosheet silica carrier is a commercially available product. During pickling, 5% dilute hydrochloric acid is used for soaking for 12 hours; the drying temperature is 120°C and the drying time is 12 hours.

[0019] Furthermore, in step (4), the enzyme activity ratio is set to 1000U enzyme activity per gram of pure, dry, modified nano silica carrier, the static adsorption environment temperature is 4℃, and the adsorption time is 24h.

[0020] Furthermore, the silicon-based supported phenol oxidase catalyst is diluted at a weight ratio of 10:1 to form a suspension as a product, which is used as a liquid catalyst for catalyzing the condensation of phenolic substances in phenolic ammonia wastewater in a weakly acidic environment.

[0021] On the other hand, the present invention also provides a wastewater treatment method based on the aforementioned silicon-based supported phenol oxidase catalyst, comprising the following steps:

[0022] S1. Oil removal, acid removal, and ammonia removal: The phenol-ammonia wastewater is treated by oil removal, acid removal, and ammonia stripping to remove emulsified oils, acidic substances, and ammonia nitrogen;

[0023] S2. Polycondensation reaction: The wastewater after deacidification and ammonia stripping is sent into the reactor, and the prepared liquid catalyst and acid are added. The mixture is stirred to carry out the polycondensation reaction, so that the phenolic substances are converted into polyphenolic flocculent substances.

[0024] S3. Separation of polyphenolic substances: The polyphenolic flocculent substances generated in step S2 are separated by precipitation, and the supernatant is collected;

[0025] S4. Electrochemical catalytic polycondensation: The supernatant from step S3 is passed into an electrochemical reactor to carry out a free radical polycondensation reaction to remove residual phenolic substances;

[0026] S5. Separation of electrochemical polycondensation products: The polyphenolic substances generated in step S4 are separated by precipitation, and the supernatant is collected.

[0027] S6. Biochemical treatment: The supernatant from step S5 is subjected to biochemical treatment using a simultaneous nitrification and denitrification process to ensure that the wastewater meets discharge standards.

[0028] Furthermore, in step S1, after the wastewater passes through the coalescence oil removal equipment to remove coal tar-like substances, it enters the deacidification tower for stripping to remove acidic substances. After heat exchange, it enters the ammonia stripping tower for stripping to remove ammonia. After condensation at the top of the tower, part of the wastewater is refluxed, and part of the ammonia water with a concentration of about 10% is collected for desulfurization and denitrification of the plant's boilers.

[0029] Furthermore, in step S2, the reactor is made of carbon steel lined with rubber, and the stirring power is 0.5 kW / m³. 3 The rotation speed is 60 rpm; the liquid catalyst is prepared by the suspension and water, and the dosage is 4 L / (ton water·h), and the dosage of concentrated sulfuric acid is 0.5 L / (ton water·h); the total reaction time is 6 h, the final pH is controlled at 3.7~4.0, the molecular weight of the polyphenols generated is 10,000~50,000, and the polycondensation yield is 80%.

[0030] Furthermore, steps S3 and S5 both employ the inclined plate sedimentation method; if separation is inadequate in S3, add 0.05 kg / ton water of polydimethylethylene ammonium chloride; if separation is inadequate in S5, add 0.05 kg / ton water of polyaluminum chloride and 0.005 kg / ton water of polyacrylamide.

[0031] Furthermore, in step S4, the electrochemical reactor is a 1.8×1.8×2.3m fixed-bed three-dimensional electrode reactor, using graphite electrode plates and carbon-based packing, with a current of 150~200A and a voltage of 20~40V, and the wastewater is retained for 1 hour; after the reaction, sodium hydroxide is added to neutralize to pH 7~8.

[0032] Furthermore, step S6 uses a tape-type fixed-bed biological packing material with a simultaneous nitrification-denitrification reflux ratio of 1:30~50.

[0033] The beneficial effects of this invention are:

[0034] This invention introduces o-dithiopyridine functional groups onto the surface of nanosheet silica through silanization modification of 3-azidopropyltrimethoxysilane and click chemistry reaction of alkyne-modified o-dithiopyridine. These functional groups can form specific disulfide covalent bonds with the thiol groups in phenol oxidase molecules. Compared with traditional physical adsorption, this significantly reduces the loss of enzyme molecules during the reaction process, allowing the catalyst to retain more than 75% of its initial enzyme activity after 5 cycles of use, thus significantly extending the catalyst's lifespan.

[0035] Nanosheet silica has an ultra-large specific surface area. During the modification process, the density of surface active sites is further increased by grafting silanizing agents and introducing linker molecules, which greatly improves the enzyme loading capacity. Moreover, the enzyme molecules are uniformly dispersed on the carrier surface, avoiding enzyme activity inhibition caused by aggregation.

[0036] The catalyst can specifically catalyze the oxidative condensation reaction of phenolic substances, converting toxic and recalcitrant monophenols / polyphenols into polyphenolic flocculent substances with a molecular weight of 10,000 to 50,000. The single condensation phenol removal yield reaches 80%, and combined with subsequent electrochemical catalytic condensation, the total phenol removal rate is increased to over 99%, completely eliminating the toxic effects of phenols on microorganisms.

[0037] Improved wastewater biodegradability and color removal: The B / C ratio of the wastewater after phenol removal increased from 0.1~0.16 to over 0.3, breaking through the bottleneck of traditional processes where phenol removal is still difficult to biodegrade, and providing favorable conditions for subsequent simultaneous nitrification and denitrification processes; In addition, the separation of polyphenolic substances simultaneously removed the chrysanthemum groups and auxochrome groups in the wastewater, with a color removal rate of over 90%, and the effluent color was reduced to less than 50 times, significantly improving sensory performance. Detailed Implementation

[0038] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments in the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the experimental materials used in the following examples are all purchased from commercial channels.

[0041] Example 1:

[0042] A silicon-based supported phenol oxidase catalyst, the preparation process of which includes the following steps:

[0043] (1) Carrier pretreatment: Take nanosheet silica carrier, wash with acid, vacuum filter, rinse with pure water until neutral, and dry to obtain pure and dry nanosheet silica carrier.

[0044] (2) Carrier modification: 1.0 g of dry nanosheet silica carrier was dispersed in 50 mL of anhydrous toluene, ultrasonically treated for 30 min, 0.48 mL of 3-azidopropyltrimethoxysilane was added dropwise under inert gas protection, heated to 80 °C, the product was separated by centrifugation, washed with toluene in sequence, and dried to obtain azido-modified silica.

[0045] 0.84 mL of propargyl acid was dissolved in 60 mL of anhydrous DMF. 1.5 g of N-hydroxysuccinimide and 2.75 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added sequentially under ice bath conditions. The mixture was activated for 4 h. 2.3 g of 2-pyridine dithioethylamine hydrochloride and 2.8 mL of triethylamine were dissolved in 50 mL of anhydrous DMF and added dropwise to the activated solution. The mixture was reacted at room temperature in the dark for 2 h. After purification by chromatographic column chromatography, alkynylated o-dithiopyridine was obtained.

[0046] 2.0 g of azide-modified silica was dispersed in 80 mL of a mixed solvent of deionized water and tert-butanol in a volume ratio of 1:1. 0.42 g of alkyne-modified o-dithiopyridine was added, followed by 0.01 g of sodium ascorbate and 0.01 g of copper sulfate pentahydrate. The mixture was reacted under an inert gas atmosphere for 12 h. The solid product was collected by centrifugation, washed alternately with EDTA solution and deionized water, and dried under vacuum to obtain modified nano-silica with o-dithiopyridine groups on the surface.

[0047] (3) Enzyme solution treatment: The phenol oxidase extract produced by bio-fermentation is concentrated;

[0048] (4) Loading and adsorption: According to the set enzyme activity ratio, the concentrated phenol oxidase extract is added dropwise to the pure dry modified nano silica carrier, stirred to make the enzyme solution fully contact the carrier, and then allowed to stand for adsorption.

[0049] (5) Cleaning and purification: The loaded carrier is cleaned multiple times with pH buffer solution to remove unadsorbed enzymes and impurities, and silicon-based supported phenol oxidase catalyst is obtained.

[0050] In step (1), the nanosheet silica carrier is a commercially available product. During pickling, 5% dilute hydrochloric acid is used for soaking for 12 hours; the drying temperature is 120℃ and the drying time is 12 hours.

[0051] In step (4), the enzyme activity ratio is set to 1000U enzyme activity per gram of pure, dry, modified nano silica carrier, the static adsorption environment temperature is 4℃, and the adsorption time is 24h.

[0052] The silicon-based supported phenol oxidase catalyst is diluted to a suspension at a weight ratio of 10:1 as a product and is used as a liquid catalyst for catalyzing the condensation of phenolic substances in phenolic ammonia wastewater in a weakly acidic environment.

[0053] Example 2:

[0054] A silicon-based supported phenol oxidase catalyst, the preparation process of which includes the following steps:

[0055] (1) Carrier pretreatment: Take nanosheet silica carrier, wash with acid, vacuum filter, rinse with pure water until neutral, and dry to obtain pure and dry nanosheet silica carrier.

[0056] (2) Carrier modification: 1.0 g of dry nanosheet silica carrier was dispersed in 65 mL of anhydrous toluene, ultrasonically treated for 30 min, 0.54 mL of 3-azidopropyltrimethoxysilane was added dropwise under inert gas protection, heated to 90 °C, the product was separated by centrifugation, washed with toluene in sequence, and dried to obtain azido-modified silica.

[0057] 0.92 mL of propargyl acid was dissolved in 80 mL of anhydrous DMF. 1.75 g of N-hydroxysuccinimide and 2.815 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added sequentially under ice bath conditions. The mixture was activated for 5 h. 2.45 g of 2-pyridine dithioethylamine hydrochloride and 3.0 mL of triethylamine were dissolved in 55 mL of anhydrous DMF and added dropwise to the activated solution. The mixture was reacted at room temperature in the dark for 2 h. After purification by chromatographic column chromatography, o-dithiopyridine alkynylation was obtained.

[0058] 3.0 g of azide-modified silica was dispersed in 90 mL of a mixed solvent of deionized water and tert-butanol in a volume ratio of 1:1. 0.46 g of alkyne-modified o-dithiopyridine was added, followed by 0.013 g of sodium ascorbate and 0.015 g of copper sulfate pentahydrate. The mixture was reacted under an inert gas atmosphere for 18 h. The solid product was collected by centrifugation, washed alternately with EDTA solution and deionized water, and dried under vacuum to obtain modified nano-silica with o-dithiopyridine groups on its surface.

[0059] (3) Enzyme solution treatment: The phenol oxidase extract produced by bio-fermentation is concentrated;

[0060] (4) Loading and adsorption: According to the set enzyme activity ratio, the concentrated phenol oxidase extract is added dropwise to the pure dry modified nano silica carrier, stirred to make the enzyme solution fully contact the carrier, and then allowed to stand for adsorption.

[0061] (5) Cleaning and purification: The loaded carrier is cleaned multiple times with pH buffer solution to remove unadsorbed enzymes and impurities, and silicon-based supported phenol oxidase catalyst is obtained.

[0062] Everything else is the same as in Example 1.

[0063] Example 3:

[0064] A silicon-based supported phenol oxidase catalyst, the preparation process of which includes the following steps:

[0065] (1) Carrier pretreatment: Take nanosheet silica carrier, wash with acid, vacuum filter, rinse with pure water until neutral, and dry to obtain pure and dry nanosheet silica carrier.

[0066] (2) Carrier modification: 1.0 g of dry nanosheet silica carrier was dispersed in 80 mL of anhydrous toluene, ultrasonically treated for 30 min, 0.6 mL of 3-azidopropyltrimethoxysilane was added dropwise under inert gas protection, heated to 85 °C, the product was separated by centrifugation, washed with toluene in sequence, and dried to obtain azido-modified silica.

[0067] 1 mL of propynic acid was dissolved in 100 mL of anhydrous DMF. 2.0 g of N-hydroxysuccinimide and 2.88 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride were added sequentially under ice bath conditions. The mixture was activated for 6 h. 2.6 g of 2-pyridine dithioethylamine hydrochloride and 3.2 mL of triethylamine were dissolved in 60 mL of anhydrous DMF and added dropwise to the activated solution. The mixture was reacted at room temperature in the dark for 2 h. After purification by chromatographic column chromatography, o-dithiopyridine alkynylation was obtained.

[0068] 4.0 g of azide-modified silica was dispersed in 100 mL of a mixed solvent of deionized water and tert-butanol in a volume ratio of 1:1. 0.5 g of alkyne-modified o-dithiopyridine was added, followed by 0.016 g of sodium ascorbate and 0.02 g of copper sulfate pentahydrate. The mixture was reacted under an inert gas atmosphere for 24 h. The solid product was collected by centrifugation, washed alternately with EDTA solution and deionized water, and dried under vacuum to obtain modified nano-silica with o-dithiopyridine groups on the surface.

[0069] (3) Enzyme solution treatment: The phenol oxidase extract produced by bio-fermentation is concentrated;

[0070] (4) Loading and adsorption: According to the set enzyme activity ratio, the concentrated phenol oxidase extract is added dropwise to the pure dry modified nano silica carrier, stirred to make the enzyme solution fully contact the carrier, and then allowed to stand for adsorption.

[0071] (5) Cleaning and purification: The loaded carrier is cleaned multiple times with pH buffer solution to remove unadsorbed enzymes and impurities, and silicon-based supported phenol oxidase catalyst is obtained.

[0072] Everything else is the same as in Example 1.

[0073] Example 4:

[0074] A wastewater treatment method based on the aforementioned silicon-based supported phenol oxidase catalyst includes the following steps:

[0075] S1. Oil removal, acid removal, and ammonia removal: The phenol-ammonia wastewater is treated by oil removal, acid removal, and ammonia stripping to remove emulsified oils, acidic substances, and ammonia nitrogen;

[0076] S2. Polycondensation reaction: The wastewater after deacidification and ammonia stripping is sent into the reactor, and the prepared liquid catalyst and acid are added. The mixture is stirred to carry out the polycondensation reaction, so that the phenolic substances are converted into polyphenolic flocculent substances.

[0077] S3. Separation of polyphenolic substances: The polyphenolic flocculent substances generated in step S2 are separated by precipitation, and the supernatant is collected;

[0078] S4. Electrochemical catalytic polycondensation: The supernatant from step S3 is passed into an electrochemical reactor to carry out a free radical polycondensation reaction to remove residual phenolic substances;

[0079] S5. Separation of electrochemical polycondensation products: The polyphenolic substances generated in step S4 are separated by precipitation, and the supernatant is collected.

[0080] S6. Biochemical treatment: The supernatant from step S5 is subjected to biochemical treatment using a simultaneous nitrification and denitrification process to ensure that the wastewater meets discharge standards.

[0081] Furthermore, in step S1, after the wastewater passes through the coalescence oil removal equipment to remove coal tar-like substances, it enters the deacidification tower for stripping to remove acidic substances. After heat exchange, it enters the ammonia stripping tower for stripping to remove ammonia. After condensation at the top of the tower, part of the wastewater is refluxed, and part of the ammonia water with a concentration of about 10% is collected for desulfurization and denitrification of the plant's boilers.

[0082] Furthermore, in step S2, the reactor is made of carbon steel lined with rubber, and the stirring power is 0.5 kW / m³. 3 The rotation speed is 60 rpm; the liquid catalyst is prepared by the suspension and water, and the dosage is 4 L / (ton water·h), and the dosage of concentrated sulfuric acid is 0.5 L / (ton water·h); the total reaction time is 6 h, the final pH is controlled at 3.7~4.0, the molecular weight of the polyphenols generated is 10,000~50,000, and the polycondensation yield is 80%.

[0083] Furthermore, steps S3 and S5 both employ the inclined plate sedimentation method; if separation is inadequate in S3, add 0.05 kg / ton water of polydimethylethylene ammonium chloride; if separation is inadequate in S5, add 0.05 kg / ton water of polyaluminum chloride and 0.005 kg / ton water of polyacrylamide.

[0084] Furthermore, in step S4, the electrochemical reactor is a 1.8×1.8×2.3m fixed-bed three-dimensional electrode reactor, using graphite electrode plates and carbon-based packing, with a current of 180A, a voltage of 30V, and wastewater retention for 1 hour; after the reaction, sodium hydroxide is added to neutralize to pH 7.

[0085] Furthermore, step S6 uses a tape-type fixed-bed biological packing material with a simultaneous nitrification-denitrification reflux ratio of 1:40.

[0086] Comparative Example 1:

[0087] In this comparative example, the unmodified nanosheet silica carrier was used instead of the modified nano silica carrier, and all other aspects were the same as in Example 3.

[0088] Results Analysis

[0089] To verify the performance of the catalysts prepared in Examples 1-3 and Comparative Example 1 in treating wastewater, the key pollutant indicators and biodegradability of the wastewater before and after treatment were tested, and the results are shown in Table 1.

[0090] Table 1 Comparison of initial phenol and ammonia wastewater quality and effluent quality after treatment with various catalysts and complete process.

[0091]

[0092] As shown in Table 1, Examples 1-3, using modified carriers and covalently immobilizing the enzymes, exhibited excellent phenol removal and high cycling stability. Comparative Example 1, using an unmodified carrier, showed enzyme detachment, leading to a significant decrease in phenol removal rate and cycling stability.

[0093] After processing by the process of this invention, the B / C ratio is increased from 0.12 to about 0.5, breaking through the bottleneck of the traditional process where it is still difficult to biochemically process after phenol removal, and laying a solid foundation for subsequent biochemical treatment.

[0094] The examples demonstrated comprehensive and efficient removal of COD, ammonia nitrogen, color, oil, and heavy metals, with effluent quality far superior to the comparative example, proving the synergistic advantages of the modified catalyst and process combination.

[0095] Data confirms that the combined process of enzyme-catalyzed polycondensation and electrochemical deep treatment can achieve near-complete removal of phenolic pollutants and significantly improve the properties of wastewater, making it meet the influent requirements for subsequent biochemical treatment.

[0096] In summary, the silicon-based supported phenol oxidase catalyst and its wastewater treatment method described in this invention are significantly superior to traditional methods using unmodified carriers in key performance aspects such as phenol removal efficiency, improved biodegradability, color removal, and catalyst stability when treating highly toxic and recalcitrant phenol and ammonia wastewater.

[0097] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0098] The present invention and its embodiments have been described above. This description is not restrictive, and the embodiments shown are only one of the embodiments of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A silicon-based supported phenol oxidase catalyst, characterized in that: Its preparation process includes the following steps: (1) Carrier pretreatment: Take nanosheet silica carrier, wash with acid, vacuum filter, rinse with pure water until neutral, and dry to obtain pure and dry nanosheet silica carrier. (2) Carrier modification: 1.0 g of dry nanosheet silica carrier was dispersed in 50-80 mL of anhydrous toluene, sonicated for 30 min, and 0.48-0.6 mL of 3-azidopropyltrimethoxysilane was added dropwise under inert gas protection. The mixture was heated to 80-90 °C, the product was separated by centrifugation, washed with toluene, and dried to obtain azido-modified silica. Dissolve 0.84–1 mL of propargyl acid in 60–100 mL of anhydrous DMF. Add 1.5–2.0 g of N-hydroxysuccinimide and 2.75–2.88 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride sequentially under ice bath conditions. Activate for 4–6 h. Dissolve 2.3–2.6 g of 2-pyridinedithioethylamine hydrochloride and 2.8–3.2 mL of triethylamine in 50–60 mL of anhydrous DMF and add dropwise to the activated solution. React at room temperature in the dark for 2 h. Purify by column chromatography to obtain alkynylated o-dithiopyridine. 2.0-4.0 g of azide-modified silica was dispersed in 80-100 mL of a mixed solvent of deionized water and tert-butanol in a volume ratio of 1:

1. 0.42-0.5 g of alkyne-modified o-dithiopyridine was added, followed by 0.01-0.016 g of sodium ascorbate and 0.01-0.02 g of copper sulfate pentahydrate. The mixture was reacted under an inert gas atmosphere for 12-24 h. The solid product was collected by centrifugation, washed alternately with EDTA solution and deionized water, and dried under vacuum to obtain modified nano-silica with o-dithiopyridine groups on its surface. (3) Enzyme solution treatment: The phenol oxidase extract produced by bio-fermentation is concentrated; (4) Loading and adsorption: According to the set enzyme activity ratio, the concentrated phenol oxidase extract is added dropwise to the pure dry modified nano silica carrier, stirred to make the enzyme solution fully contact the carrier, and then allowed to stand for adsorption. (5) Cleaning and purification: The loaded carrier is cleaned multiple times with pH buffer solution to remove unadsorbed enzymes and impurities, and silicon-based supported phenol oxidase catalyst is obtained.

2. The silicon-based supported phenol oxidase catalyst according to claim 1, characterized in that: In step (1), the nanosheet silica carrier is a commercially available product. During pickling, 5% dilute hydrochloric acid is used for soaking for 12 hours; the drying temperature is 120℃ and the drying time is 12 hours.

3. The silicon-based supported phenol oxidase catalyst according to claim 1, characterized in that: In step (4), the enzyme activity ratio is set to 1000U enzyme activity per gram of pure, dry, modified nano silica carrier, the static adsorption environment temperature is 4℃, and the adsorption time is 24h.

4. The silicon-based supported phenol oxidase catalyst according to claim 1, characterized in that: The silicon-based supported phenol oxidase catalyst is diluted to a suspension at a weight ratio of 10:1 as a product and is used as a liquid catalyst for catalyzing the condensation of phenolic substances in phenolic ammonia wastewater in a weakly acidic environment.

5. A wastewater treatment method based on the silicon-based supported phenol oxidase catalyst according to any one of claims 1-4, characterized in that: Includes the following steps: S1. Oil removal, acid removal, and ammonia removal: The phenol-ammonia wastewater is treated by oil removal, acid removal, and ammonia stripping to remove emulsified oils, acidic substances, and ammonia nitrogen; S2. Polycondensation reaction: The wastewater after deacidification and ammonia stripping is sent into the reactor, and the prepared liquid catalyst and acid are added. The mixture is stirred to carry out the polycondensation reaction, so that the phenolic substances are converted into polyphenolic flocculent substances. S3. Separation of polyphenolic substances: The polyphenolic flocculent substances generated in step S2 are separated by precipitation, and the supernatant is collected; S4. Electrochemical catalytic polycondensation: The supernatant from step S3 is passed into an electrochemical reactor to carry out a free radical polycondensation reaction to remove residual phenolic substances; S5. Separation of electrochemical polycondensation products: The polyphenolic substances generated in step S4 are separated by precipitation, and the supernatant is collected. S6. Biochemical treatment: The supernatant from step S5 is subjected to biochemical treatment using a simultaneous nitrification and denitrification process to ensure that the wastewater meets discharge standards.

6. The wastewater treatment method according to claim 5, characterized in that: In step S1, after the wastewater passes through the coalescence oil removal equipment to remove coal tar-like substances, it enters the deacidification tower for stripping to remove acidic substances, and then enters the ammonia stripping tower for stripping to remove ammonia after heat exchange. After condensation at the top of the tower, part of the wastewater is refluxed, and part of the ammonia water with a concentration of about 10% is collected for desulfurization and denitrification of the boiler in the plant area.

7. The wastewater treatment method according to claim 5, characterized in that: In step S2, the reactor is made of carbon steel lined with rubber, and the stirring power is 0.5 kW / m³. 3 The rotation speed is 60 rpm; the liquid catalyst is prepared by the suspension and water, and the dosage is 4 L / (ton water·h), and the dosage of concentrated sulfuric acid is 0.5 L / (ton water·h); the total reaction time is 6 h, the final pH is controlled at 3.7~4.0, the molecular weight of the polyphenols generated is 10,000~50,000, and the polycondensation yield is 80%.

8. The wastewater treatment method according to claim 5, characterized in that: Both steps S3 and S5 employ the inclined plate sedimentation method. If separation in S3 is inadequate, add 0.05 kg / ton water of polydimethyldiethylene ammonium chloride. If separation in S5 is inadequate, add 0.05 kg / ton water of polyaluminum chloride and 0.005 kg / ton water of polyacrylamide.

9. The wastewater treatment method according to claim 5, characterized in that: In step S4, the electrochemical reactor is a 1.8×1.8×2.3m fixed-bed three-dimensional electrode reactor, using graphite electrode plates and carbon-based packing, with a current of 150~200A and a voltage of 20~40V, and the wastewater is retained for 1 hour; after the reaction, sodium hydroxide is added to neutralize to pH 7~8.

10. The wastewater treatment method according to claim 5, characterized in that: Step S6 uses a tape-type fixed bed biological packing material with a simultaneous nitrification-denitrification reflux ratio of 1:30~50.

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