Composite treatment agent, preparation thereof and application of composite treatment agent in perchlorate wastewater

Abstract

The invention belongs to the field of wastewater treatment, and particularly relates to a composite treating agent and preparation and application thereof in perchlorate wastewater, and the composite treating agent is characterized by comprising modified kaolinite and enzyme; the modified kaolinite is a ferroferric oxide part in-situ coated kaolinite material, and comprises kaolinite and ferroferric oxide nanoparticles deposited on part of the surface of the kaolinite in situ; the enzyme comprises protease and / or lipase. The invention provides a ferroferric oxide partial in-situ coated kaolinite material, which is based on the combination of the special physicochemical characteristics of kaolinite and the special partial in-situ coating characteristics of ferroferric oxide, so that the material can adapt to the degradation characteristics of heterotrophic microorganisms of perchlorate, and is beneficial to improving the degradation effect of perchlorate; the method is especially suitable for complex perchloric acid wastewater containing ammonia nitrogen and nitrate nitrogen synchronously.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sewage treatment, and particularly relates to a preparation and application of a treatment agent for improving the degradation effect of perchlorate heterotrophic microorganisms. BACKGROUND

[0002] Perchlorate is widely used in the manufacture of fireworks and aerospace industry. The harm of perchlorate mainly enters the organism through the digestive respiratory system (such as drinking water contaminated by perchlorate and breathing air containing perchlorate dust), which has certain toxicity to the thyroid, nervous system, growth and development, and reproductive system of the organism.

[0003] The removal methods of perchlorate in wastewater include activated carbon adsorption, chemical reduction and biological method. For example, the patent document with the publication number CN119161063A1 discloses a perchlorate wastewater treatment method, which specifically records a method of biodegrading perchlorate wastewater in a microbial catalytic tank. The patent document with the publication number CN118324244A discloses a method for efficiently degrading perchlorate based on biorenewable resin and its application.

[0004] Among these methods, the biological method has the advantages of easy operation and low running cost. The biological method includes autotrophic reduction method and heterotrophic reduction method (also called heterotrophic microbial degradation of perchlorate method).

[0005] At present, the heterotrophic microbial degradation of perchlorate is generally considered to be a promising perchlorate removal technology, which is more suitable for large-scale industrial wastewater treatment. This method usually needs to add organic carbon source as an electron donor, and has the advantages of fast degradation rate, easy operation and management.

[0006] However, the heterotrophic microbial degradation of perchlorate currently has the following main problems: ① poor degradation effect of perchlorate at low temperature (2~5℃), because most of the reduction bacteria are mesophilic bacteria and cannot survive when the temperature is lower than 5℃; ② high concentration of nitrate and perchlorate exist in the wastewater system at the same time, and nitrate (referred to as nitrate nitrogen) will be preferentially degraded, resulting in a great decrease in the microbial degradation rate of perchlorate; ③ ammonia nitrogen and perchlorate exist in the wastewater system at the same time, which also greatly reduces the microbial degradation rate of perchlorate.

[0007] In summary, the simultaneous existence of ammonia nitrogen and high-concentration nitrate nitrogen or the removal of perchlorate at low temperature in perchlorate wastewater is difficult, especially the simultaneous removal of perchlorate, nitrate nitrogen and ammonia nitrogen. In view of this main problem, there is an urgent need for an efficient treatment method for the heterotrophic microbial degradation of perchlorate. SUMMARY

[0008] The first purpose of the present application is to provide the composite treatment agent, aiming at improving the heterotrophic microbial degradation efficiency and effect of perchlorate wastewater, especially complex wastewater, based on the combination of ingredients.

[0009] The second purpose of the present application is to provide the preparation method of the composite treatment agent and its treatment application in wastewater.

[0010] The heterotrophic microbial degradation effect of perchlorate wastewater is not ideal, especially for complex perchlorate wastewater containing ammonia nitrogen and nitrate nitrogen, the degradation activity and efficiency are significantly increased, and the present application provides the following improvement scheme for the treatment problem of the complex wastewater after in-depth research.

[0011] The composite treatment agent comprises modified kaolinite and enzymes.

[0012] The modified kaolinite is a part of iron tetroxide in situ coated kaolinite material, which comprises kaolinite and iron tetroxide nanoparticles deposited in situ on part of the surface of the kaolinite.

[0013] The enzymes comprise protease and / or lipase.

[0014] The present application provides a part of iron tetroxide in situ coated kaolinite material, which is based on the combination of the special physicochemical characteristics of kaolinite and the special part of in situ coating characteristics of the iron tetroxide, so as to adapt to the characteristics of heterotrophic microbial degradation of perchlorate, which helps to improve the degradation effect of perchlorate, especially for complex perchlorate wastewater containing ammonia nitrogen and nitrate nitrogen. In addition, the part of iron tetroxide in situ coated kaolinite material is innovatively combined with protease and lipase, which can further realize the synergy and strengthen the heterotrophic microbial degradation activity and efficiency of perchlorate wastewater, especially complex perchlorate wastewater.

[0015] In the modified kaolinite of the present application, the area covered by the iron tetroxide nanoparticles accounts for 30-60% of the surface area of the kaolinite.

[0016] Preferably, the iron tetroxide is deposited on one surface of the kaolinite.

[0017] Preferably, the weight ratio of iron tetroxide to kaolinite is 0.2-0.4:1.

[0018] In the present application, the preparation method of the modified kaolinite comprises mixing kaolinite and coupling agent, then adding water and hydrophobic solvent for ultrasonic emulsification to obtain O / W emulsion.

[0019] Subsequently, a water-soluble ferric salt, a water-soluble ferrous salt and an alkaline component are added to the O / W emulsion to deposit the magnetite nanoparticles in situ on the surface of the kaolinite in contact with the water phase in the O / W emulsion to obtain the modified kaolinite.

[0020] The application also provides an O / W type magnetite in-situ precipitation preparation method, which innovatively disperses the kaolinite between the water-oil interface of the O / W emulsion, soaks one side of the kaolinite in the oil phase and the other side in the water phase, and then selectively precipitates the magnetite nanoparticles in situ on the surface of the kaolinite on the water phase side. The method can prepare a partially asymmetric modified kaolinite structure material, and the material prepared by the method can adapt to the degradation conditions of perchlorate heterotrophic microorganisms, and can obtain a better perchlorate degradation effect. Especially for the complex perchlorate wastewater containing ammonia nitrogen and nitrate nitrogen which is difficult to be effectively treated by the prior art, excellent degradation rate and degradation efficiency can also be obtained.

[0021] In the application, the coupling agent is at least one of a conventional titanate coupling agent and a silane coupling agent.

[0022] For example, the silane coupling agent can be a conventional coupling agent containing a (RO) 3 Si- structure. The titanate coupling agent can be a conventional coupling agent containing a (RO) 3 Ti- structure. The R is methyl, ethyl, propyl or butyl, etc.

[0023] The silane coupling agent can be at least one of KH-570, KH-560, KH-590, vinyl triethoxysilane, etc. The titanate coupling agent is at least one of isopropyl tri(dioctyl pyrophosphoryloxy) titanate, KR-38S (isopropyl di(dioctyl pyrophosphoryloxy) titanate), TTS (tetraisopropyl bis(dioctyl pyrophosphoryloxy) titanate), etc.

[0024] In the application, the kaolinite has an asymmetric structure by nature, the crystal is stacked by “silicon-oxygen tetrahedral sheet (Si-O)” and “aluminum-oxygen octahedral sheet (Al-OH)” through hydrogen bonds, and the surface properties of the two layers are completely different. The coupling agent treatment of the kaolinite can make the obtained modified kaolinite become a “dual parent structure” of “strong hydrophobic on one side (aluminum-oxygen side) and hydrophobic / weak hydrophilic on the other side (silicon-oxygen side)”, thereby facilitating the in-situ deposition of magnetite on the weak hydrophilic side under the driving of thermodynamics.

[0025] The weight ratio of kaolinite to coupling agent is 1:0.005-0.025; preferably 1:0.01-0.015; further 1:0.01-0.05.

[0026] In the present application, kaolinite and coupling agent are combined, and then ultrasonic emulsification is carried out with water and a hydrophobic solvent to obtain an O / W emulsion, so that the surface of the kaolinite is partially immersed (contacted) in the oil phase and partially immersed (contacted) in the water phase; then water-soluble ferric salt, water-soluble ferrous salt and alkaline component are added to the O / W emulsion, so that the surface of the kaolinite immersed in the water phase is in-situ deposited with Fe3O4 nanoparticles to prepare the modified kaolinite.

[0027] The hydrophobic solvent is a C4-C8 hydrocarbon solvent; for example, it can be cyclopentane, cyclohexane, cycloheptane, n-hexane, n-heptane, etc. 10 The hydrophobic solvent is a C4-C8 hydrocarbon solvent; for example, it can be cyclopentane, cyclohexane, cycloheptane, n-hexane, n-heptane, etc.

[0028] Preferably, the volume ratio of water to hydrophobic solvent is 1:0.5-5; further, 1:1-1.5.

[0029] The volume weight ratio of the total solvent of water and hydrophobic solvent to kaolinite is 5-20 mL / g, further, 10-15 mL / g.

[0030] The water-soluble ferrous salt is at least one of ferrous chloride, ferrous sulfate, ferrous nitrate and ferrous acetate;

[0031] Preferably, the water-soluble ferrous salt is at least one of ferric chloride, ferric sulfate and ferric nitrate;

[0032] In the present application, the molar ratio of Fe 2+ , Fe 3+ is 2-4:1.

[0033] The mass ratio of kaolinite to water-soluble ferrous salt is 2-5:1, further, 3-4:1. The present application finds that under the preferred ratio, the simultaneous removal effect of nitrate nitrogen, ammonia nitrogen and perchlorate in wastewater can be further improved.

[0034] In the present application, the temperature of in-situ deposition is not particularly required, for example, it can be 50-60℃.

[0035] Preferably, the alkaline component is at least one of NH3·H2O, NaOH and KOH, and the solute concentration can be 1-3 mol / L.

[0036] Preferably, the pH of the in-situ deposition process is 10-12.

[0037] The in-situ deposition reaction time is 2-3h.

[0038] In the present application, the in-situ deposition process can be carried out in a protective gas such as Ar or nitrogen.

[0039] The research of the present application shows that the combination of modified kaolinite and protease and lipase can utilize the asymmetric ferroferric oxide composition and asymmetric structure of kaolinite surface, and can enhance the synergistic activity of protease and lipase, and can improve the heterotrophic microbial degradation activity and efficiency of complex perchlorate wastewater.

[0040] The present application innovatively finds that the ferroferric oxide nano-coating layer of the modified kaolinite is easy to combine with protease, and the uncoated kaolinite is easy to combine with lipase, and the combination of the modified kaolinite and the enzyme of the present application can play a synergistic effect, and can significantly improve the heterotrophic microbial degradation effect of perchlorate, and can realize the simultaneous removal of nitrate, ammonia nitrogen and perchlorate, and can significantly improve the heterotrophic microbial degradation effect of perchlorate at low temperature (2℃~6℃, especially 3~5℃).

[0041] In the present application, the lipase and protease are both enzymes subjected to activation treatment. The activation method can be recognized in the industry, and in the present application, the enzyme is preferably placed in a phosphate buffer for activation.

[0042] Preferably, the enzyme in the composite treatment agent includes protease and lipase.

[0043] Preferably, the content of protease in the composite treatment agent can be 5000~20000U / g, further can be 8000~16000U / g, and more further can be 9000U / g~11000U / g; the content of lipase can be 3000~20000U / g, further can be 4000~16000U / g, and more further can be 5000~7000U / g.

[0044] The present application also provides a preparation method of the composite treatment agent, which is obtained by compounding each component.

[0045] For example, the preparation method is as follows:

[0046] First step (S1): activate the lipase and protease respectively to obtain activated lipase and protease.

[0047] Second step (S2): partially coat the kaolinite with ferroferric oxide nanoparticles to obtain modified kaolinite.

[0048] Third step (S3): mix the activated lipase, protease and modified kaolinite in a certain proportion to obtain a series of treatment agents.

[0049] The present application also provides an application of the composite treatment agent, which is used for the treatment of perchlorate wastewater.

[0050] In the application, the concentration of perchlorate in the perchlorate wastewater is 50-1500 mg / L, further can be 200-1200 mg / L, and more further can be 700-1200 mg / L. In the application, even for high-concentration wastewater, excellent degradation capacity can be obtained, especially in low temperature and complex water body, excellent degradation capacity can also be obtained.

[0051] Preferably, the perchlorate wastewater is wastewater containing ammonia nitrogen and / or nitrate nitrogen synchronously.

[0052] Further, due to the excellent performance of the composite treatment agent, it can be adapted to the wastewater system containing nitrate nitrogen, ammonia nitrogen and perchlorate which is difficult to treat in the industry.

[0053] For example, as an optional solution, the concentration of perchlorate (calculated as perchlorate) in the perchlorate wastewater is 50-1500 mg / L, further can be 200-1200 mg / L, for example, can be 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L, 800 mg / L, 900 mg / L, 1000 mg / L, 1100 mg / L, 1200 mg / L and any combination range of wastewater. The concentration of nitrate (calculated as nitrate nitrogen) is 50-800 mg / L, for example, can be 100-700 mg / L, further can be 100 mg / L, 200 mg / L, 300 mg / L, 400 mg / L, 500 mg / L, 600 mg / L, 700 mg / L and any combination range of wastewater. The concentration of ammonia nitrogen is 20-200 mg / L, for example, can be 80-120 mg / L, for example, can be further 20 mg / L, 30 mg / L, 40 mg / L, 50 mg / L, 60 mg / L, 70 mg / L, 80 mg / L, 90 mg / L, 100 mg / L, 110 mg / L, 120 mg / L, 130 mg / L, 1400 mg / L and any combination range of wastewater.

[0054] In the application, in addition to adding the treatment agent, other operations and parameters of the perchlorate heterotrophic microbial degradation process can be conventional.

[0055] Preferably, the amount of the composite treatment agent in the treatment process is 100-500 mg / L, for example, can be 200-400 mg / L, further can be 250-350 mg / L.

[0056] For example, in the process of heterotrophic microbial degradation of perchlorate, the pH value is controlled at 7-7.5, the temperature is 2-35℃, and the dissolved oxygen is 0.05-0.2 mg / L.

[0057] For example, in the wastewater treatment process of the present application, activated sludge is added to the sequencing batch reactor in advance, then the treating agent of the present application and the wastewater to be treated are added, and then heterotrophic microbial degradation treatment is carried out.

[0058] Preferably, the activated sludge is the sludge in the anaerobic tank of a sewage treatment plant, and the sludge concentration (MLSS) is 3000-5000 mg / L.

[0059] In the present application, the temperature of the wastewater treatment process is not particularly required, but in the present application, thanks to the innovative use of the treatment, it can be highly treated at a low temperature that is difficult to achieve in the industry, such as a temperature of 2-10℃, and further can be 3-5℃.

[0060] The wastewater treatment time of the present application can be reasonably adjusted as required, for example, it can be 4-7 days.

[0061] In the present application, the treating agent can be added to the conventional heterotrophic microbial degradation perchlorate process technology, which can effectively enrich the bacteria capable of degrading perchlorate, thereby improving the effect of heterotrophic microbial degradation of perchlorate. In addition, the addition of the treating agent solves the main problems that the effect of heterotrophic microbial degradation of perchlorate is poor and it is difficult to achieve simultaneous removal of nitrate, ammonia and perchlorate when the temperature is lower than 5℃ (3-5℃) and ammonia nitrogen and high-concentration nitrate and perchlorate exist at the same time.

[0062] Beneficial effects:

[0063] The present application provides a modified kaolinite and an O / W asymmetric in-situ deposition preparation method thereof. The research of the present application shows that the modified kaolinite can adapt to the heterotrophic microbial degradation effect of perchlorate, and help to improve its degradation efficiency and effect.

[0064] The present application also provides a combination comprising the modified kaolinite and lipase and protease, so that based on the partial ferroferric oxide loading structure of the modified kaolinite and the special adaptation relationship between the lipase and the protease, the heterotrophic microbial degradation efficiency and effect of perchlorate wastewater can be significantly improved, especially for the complex perchlorate wastewater containing nitrate-ammonia which is difficult to treat in the industry, excellent degradation efficiency and degradation ability at low temperature can also be obtained. BRIEF DESCRIPTION OF DRAWINGS

[0065] Figure 1 SEM images of untreated kaolinite (left) and modified kaolinite prepared in Example 1 (right). As can be seen from the figure, the surface of the kaolinite is deposited with ferroferric oxide nanoparticles.

[0066] Figure 2The UV-visible spectrum of the modified kaolinite in the process of testing the enzyme activity. It can be seen from the figure that a strong absorption peak appears near 652 nm, which proves that it has good enzyme activity.

[0067] Figure 3 The XRD pattern of the modified kaolinite prepared at different pH values. It can be seen from the figure that the diffraction peaks of Fe3O4 are located at 30.21°, 35.48°, 43.29°, 53.74° and 57.09°, corresponding to the crystal faces (220), (311), (400), (422) and (511), respectively, which are consistent with the standard PDF card (JCPDS Card No. 89-4319) of Fe3O4. The diffraction peak of kaolinite is located at 62.5°, corresponding to the crystal face (240), which is consistent with the standard PDF card JCPDS No. 01-078-2109.

[0068] Figure 4 The room temperature hysteresis loop of the modified kaolinite prepared at different pH values. It can be seen from the figure that the modified kaolinite prepared does not appear hysteresis phenomenon, and produces closed hysteresis loop, at the same time, has high saturation magnetization, which further proves that the Fe3O4 nanoparticles are coated on the surface of kaolinite.

[0069] Figure 5 The colony test situation figure, wherein, attached Figure 5 -a: The microbial community in the sludge without adding treatment agent in the wastewater containing only 800 mg / L of perchlorate at 26°C. Attached Figure 5 -b: The microbial community in the sludge without adding treatment agent in the wastewater containing 600 mg / L of nitrate nitrogen, 100 mg / L of ammonia nitrogen and 800 mg / L of perchlorate at 3°C. Attached Figure 5 -c: The microbial community in the sludge with 300 mg / L of treatment agent in the wastewater containing 600 mg / L of nitrate nitrogen, 100 mg / L of ammonia nitrogen and 800 mg / L of perchlorate at 3°C. From the attached Figure 5 -a~attached Figure 5 -c can be seen, compared with not adding treatment agent (attached Figure 5 -a and attached Figure 5 -b), adding treatment agent (attached Figure 5 -c) is beneficial to the increase of the percentage of β-proteobacteria and β-Acidobacteriota which are perchlorate heterotrophic microbial degradation. For the case without adding treatment agent, compared with the wastewater containing only perchlorate (attached Figure 5 -a), the wastewater system containing nitrate nitrogen, ammonia nitrogen and perchlorate at low temperature (attached Figure 5- b) the percentage of the phylum of beta-proteobacteria and beta-Acidobacteriota, which are beneficial to the degradation of perchlorate heterotrophic microorganisms, decreased. DETAILED DESCRIPTION

[0070] In order to make the purpose, method and advantages of the present application clearer, the technical solutions adopted by the present application will be described in detail below with examples. The specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0071] The present application is not limited by the embodiments described herein.

[0072] Experimental materials:

[0073] The perchlorate wastewater was prepared by simulation, and the water quality was as follows: perchlorate concentration of 50-1500 mg / L, nitrate concentration of 50-800 mg / L, and ammonia nitrogen concentration of 20-200 mg / L.

[0074] Part of the detection method and standard:

[0075] Determination of ClO4 - was performed using a CIC-D120 ion chromatograph; determination of nitrate was performed according to HJ / T 346-2007 ultraviolet spectrophotometry; and determination of ammonia nitrogen was performed according to HJ 535-2009.

[0076] The treatment process for perchlorate heterotrophic microbial degradation described in the present application comprises the following steps:

[0077] (1) Inoculation of sludge. The sludge used for heterotrophic microbial degradation of perchlorate in the present application is derived from the sludge in the anaerobic tank of a conventional sewage treatment plant (for example, the sludge in the anaerobic tank of a sewage treatment plant in Changsha Yuelu District), and the sludge concentration can be, for example, 3000-5000 mg / L;

[0078] (2) During the process of perchlorate heterotrophic microbial degradation, the influent perchlorate concentration is 50-1500 mg / L, sodium acetate is added as a carbon source, the pH value is 7.0-7.5, the pH value is controlled by an automatic pH control system during the process, the temperature is between 2-35°C, the dissolved oxygen is 0.05-0.2 mg / L, and the anaerobic stirring time is 6-18 hours.

[0079] (3) The reactor for perchlorate heterotrophic microbial degradation is a sequencing batch reactor, the effective volume of the reactor is 5 L, a stirring rod is placed at the bottom, and pH and dissolved oxygen online monitoring probes are installed inside the reactor. The online monitoring probes transmit data to the PLC control cabinet in real time, the PLC control cabinet controls the stop of the peristaltic pump by setting the pH value, and the acid solution is added dropwise. The added acid solution is a 3 mol / L H2SO4 solution.

[0080] In the present application, the enzyme can be activated based on conventional means, for example:

[0081] 2g of lipase was added into a 100mL conical flask with a plug, 50mL of phosphate buffer solution (0.05mol / L, pH 7.5) was added, and the enzyme was uniformly dispersed in the buffer solution by oscillation in a constant temperature oscillator, the temperature was controlled at 25~30℃, and the enzyme was activated for 30min;

[0082] 2g of protease was added into a 100mL conical flask with a plug, 50mL of phosphate buffer solution (0.05mol / L, pH 7.5) was added, and the enzyme was uniformly dispersed in the buffer solution by oscillation in a constant temperature oscillator, the temperature was controlled at 25~30℃, and the enzyme was activated for 30min;

[0083] Example 1

[0084] Step 1: Preparation of modified kaolinite:

[0085] The original kaolinite was soaked with distilled water, washed and dried, then crushed by a pulverizer and sieved through a 200-mesh screen for use. Silane coupling agent (such as KH-570) was added to the kaolinite powder sieved through a 200-mesh screen (7g of kaolinite), the weight ratio of kaolinite to silane coupling agent was 1:0.01, stirred at 60℃ for 1 hour, then poured into a 250mL three-necked flask, 50mL of deionized water and 50mL of n-hexane were added to the three-necked flask, stirred at room temperature for 10 minutes and then ultrasonically emulsified for 20 minutes to obtain an O / W type Pickering emulsion (at this time, the kaolinite particles were adsorbed on the surface of the n-hexane oil droplets, and half of the particles were in the oil phase and half were in the water phase). High-purity nitrogen was introduced into the prepared O / W type Pickering emulsion for 10 minutes, and then a mixed solution of ferrous chloride and ferric chloride in a certain proportion was slowly added to the emulsion at room temperature, and the mixture was continuously stirred for 30 minutes to make it uniformly dispersed, then the temperature was increased to 40℃, and NaOH solution was slowly added at this temperature to adjust the pH value of the emulsion to 11, and the reaction was stopped when black precipitate appeared. After the reaction was completed, 50mL of anhydrous ethanol was added to the three-necked flask to break the emulsion, and centrifuged at 3000rpm for 10 minutes to collect the black precipitate. The black precipitate was washed with deionized water and ethanol alternately for 3~5 times to remove residual oil phase, unreacted salt and coupling agent. The washed black precipitate was dried at 60℃ under vacuum for 12 hours, ground to obtain Fe3O4 magnetic nanoparticles coated kaolinite particles, which were simply denoted as modified kaolinite (Fe3O4: kaolinite = 0.3:1).

[0086] The Fe 2+ , Fe3+ The molar ratio of the silane coupling agent to the kaolinite is 3:1, and the mass ratio of the kaolinite to the ferrous chloride is 3:1; the molar concentration of the NaOH solution is 3M; and the total reaction time from adding the silane coupling agent to the kaolinite powder to the appearance of the black precipitate is 3h.

[0087] Step 2: composite treatment agent

[0088] Phosphate buffer solution (0.05 mol / L) with pH=7.5 was prepared and preheated in a 25~30 ℃ water bath. Lipase (6000 U / g carrier) and protease (10000 U / g carrier) were weighed according to the proportion, added into the buffer solution, and stirred at 28 ℃ and 200 rpm for 15~20 min to obtain a uniform mixed enzyme solution; the modified kaolinite was added into the mixed enzyme solution, the temperature was adjusted to 32 ℃, and gentle stirring was maintained at 200~300 rpm for 2~3 h; after the combination was completed, the carrier-enzyme complex was separated by a magnet (magnetic response time <30 s), and the complex was washed with the buffer solution for 2~3 times (to remove the free enzymes not combined) and then used for subsequent catalytic reaction. The separated complex is the treatment agent (referred to as: treatment agent) added in the perchlorate heterotrophic microbial degradation process of the application.

[0089] Example 2

[0090] Compared with Example 1, the only difference is that the weight ratio of the kaolinite to the silane coupling agent in step 1 is changed to 1:0.02, and the other operations and parameters are the same as those in Example 1.

[0091] Example 3

[0092] Compared with Example 1, the only difference is that the conditions of step 2 are changed, the enzyme only contains protease, and the immobilization amount of the protease is 16000 U / g carrier, and the other operations and parameters are the same as those in Example 1.

[0093] Example 4

[0094] Compared with Example 1, the only difference is that the conditions of step 2 are changed, the enzyme only contains lipase, and the immobilization amount of the lipase is 16000 U / g carrier, and the other operations and parameters are the same as those in Example 1.

[0095] Example 5

[0096] Compared with Example 1, the only difference is that the conditions of step 2 are changed, and the immobilization amounts of the protease and the lipase are changed, specifically: the immobilization amount of the lipase is 10000 U / g carrier; the immobilization amount of the protease is 15000 U / g carrier, and the other operations and parameters are the same as those in Example 1.

[0097] Example 6

[0098] The difference compared with Example 1 is only that the step conditions are changed, and the difference step is:

[0099] Step 1:

[0100] The original kaolinite is soaked with distilled water, washed and dried, and then crushed by a pulverizer and sieved through a 200-mesh sieve for use. Silane coupling agent (such as vinyltriethoxysilane) is added to the kaolinite powder sieved through a 200-mesh sieve (kaolinite is 8 g) at a weight ratio of kaolinite to silane coupling agent of 1:0.015, stirred at 60°C for 1 hour, then poured into a 250-mL three-necked flask, 50 mL of deionized water and 70 mL of n-hexane are added to the three-necked flask, stirred at room temperature for 10 minutes, and then ultrasonically emulsified for 20 minutes to obtain an O / W type Pickering emulsion (at this time, the kaolinite particles are adsorbed on the surface of the n-hexane oil droplets, and half of the particles are in the oil phase and half are in the water phase). A certain proportion of a mixed solution of ferrous chloride and ferric chloride is slowly added to the prepared O / W type Pickering emulsion at room temperature, and the mixture is stirred for 30 min to disperse uniformly, then the temperature is increased to 40°C, and a NaOH solution is slowly added at this temperature to adjust the pH value of the emulsion to 12, and the reaction is stopped when black precipitate appears. After the reaction is completed, 50 mL of anhydrous ethanol is added to the three-necked flask to break the emulsion, and centrifuged at 3000 rpm for 10 minutes, and the black precipitate is collected. The black precipitate is washed with deionized water and ethanol alternately for 3-5 times to remove residual oil phase, unreacted salt and coupling agent. The washed black precipitate is dried at 60°C under vacuum for 12 hours, and then ground to obtain kaolinite particles coated with ferroferric oxide magnetic nanoparticles, which is simply denoted as modified kaolinite. The molar ratio of Fe 2+ 3+ in the mixed solution of ferrous chloride and ferric chloride is 2:1, and the mass ratio of kaolinite to ferrous chloride is 4:1; the molar concentration of the NaOH solution is 3M; and the total reaction time from the addition of the silane coupling agent to the kaolinite powder to the appearance of black precipitate is 3h.

[0101] Step 2: composite treatment agent

[0102] ​Phosphate buffer solution (0.05 mol / L) with pH=7.5 was prepared and preheated in a 25~30 ℃ water bath. Lipase (5500 U / g carrier) and protease (11000 U / g carrier) were weighed according to the proportion, added into the buffer solution, and stirred at 28 ℃ and 200 rpm for 15~20 min to obtain a uniform mixed enzyme solution; modified kaolinite was added into the mixed enzyme solution, the temperature was adjusted to 32 ℃, and gentle stirring was maintained at 200~300 rpm for 2~3 h; after the combination was completed, the carrier-enzyme complex was separated by a magnet (magnetic response time < 30 s), and the complex was washed with buffer solution for 2~3 times (to remove the free enzymes not combined) and then used for subsequent catalytic reaction. The separated complex is the treatment agent (referred to as: treatment agent) added in the perchlorate heterotrophic microbial degradation process of the application.

[0103] Comparative Example 1

[0104] Compared with Example 1, the only difference is that in Step 1, the kaolinite is not treated, but directly subjected to the treatment in Step 2. The other operations and parameters are the same as those in Example 1, and Comparative Treatment Agent 1 is prepared.

[0105] Comparative Example 2

[0106] Compared with Example 1, the only difference is that in Step 1, the modified kaolinite material is not prepared by the emulsion method, that is, no coupling agent is added, and in addition, an equal volume of water is used to replace n-hexane. The other operations and parameters are the same as those in Example 1. Comparative Treatment Agent 2 is prepared.

[0107] Comparative Example 3

[0108] Compared with Example 1, the only difference is that in Step 1, montmorillonite is used to replace kaolinite. The other operations and parameters are the same as those in Example 1, and the corresponding Comparative Treatment Agent 3 is prepared.

[0109] Comparative Example 4

[0110] Compared with Example 1, the only difference is that in Step 1, maifanite is used to replace kaolinite. The other operations and parameters are the same as those in Example 1, and the corresponding Comparative Treatment Agent 4 is prepared.

[0111] Comparative Example 5

[0112] Compared with Example 1, the only difference is that Step 2 is not performed, and the modified kaolinite is directly used as the treatment agent to prepare Comparative Treatment Agent 5.

[0113] 1.2: Record the degradation effect

[0114] Test 1:

[0115] The simulated wastewater with perchlorate concentration of 800 mg / L, nitrate concentration of 600 mg / L and ammonia nitrogen concentration of 100 mg / L is used as the influent of the experiment, sodium acetate is used as the carbon source, the sludge concentration is 3500 mg / L, the pH value is 7.0-7.5 during the experiment, the dissolved oxygen is 0.2 mg / L, the experimental temperature is 26℃, 300 mg / L (referring to the ratio of the added treatment agent mass to the total volume of sludge and wastewater in the reactor) of the treatment agent is poured into the sequencing batch reactor (the reaction volume is 5L), it is taken every 1d, the removal rates of perchlorate, ammonia nitrogen and nitrate are calculated, the effluent after 4d treatment is taken, and the concentrations of perchlorate, ammonia nitrogen and nitrate are measured (the results are shown in Table 1).

[0116]

[0117] Test 2:

[0118] The treatment agent is prepared according to Example 1, sodium acetate is used as the carbon source, the pH value is 7.0-7.5 during the experiment, the dissolved oxygen is 0.05-0.2 mg / L, the sludge concentration is 3000-5000 mg / L, the treatment agent is added to the reactor at a dosage of 300 mg / L, and the perchlorate heterotrophic microbial degradation experiment under different perchlorate contents and different temperatures is carried out. The water is taken out every 1d, the removal rates of perchlorate, ammonia nitrogen and nitrate are calculated, the effluent after 4d treatment is taken, and the concentrations of perchlorate, ammonia nitrogen and nitrate are measured, and the results are shown in Table 2.

[0119]

[0120] Test 3:

[0121] The treatment agent prepared according to each of the comparative examples is used for the treatment of Test 1, and the results are shown in Table 3.

[0122]

[0123]

[0124] Note: The data in Table 4-a is from Appendix Figure 5 -a; the data in Table 4-b is from Appendix Figure 5 -b; the data in Table 4-c is from Appendix ​ -c.

Claims

1. A complex treatment agent, characterized by, The modified kaolinite comprises a modified kaolinite and an enzyme. The modified kaolinite is a part of the in-situ coated kaolinite material, which comprises kaolinite and in-situ deposited ferroferric oxide nanoparticles on part of the surface of the kaolinite. The enzyme comprises a protease and / or a lipase.

2. The composite treatment of claim 1, wherein, In the modified kaolinite, the area covered by the ferroferric oxide nanoparticles accounts for 30-60% of the surface area of the kaolinite. Preferably, the ferroferric oxide is deposited on one surface of the kaolinite. Preferably, the weight ratio of the ferroferric oxide to the kaolinite is 0.2-0.4:

1.

3. The complexing agent according to claim 1 or 2, wherein The preparation method of the modified kaolinite comprises mixing the kaolinite and a coupling agent, and then adding water and a hydrophobic solvent for ultrasonic emulsification to obtain an O / W emulsion. Subsequently, water-soluble ferric salt, water-soluble ferrous salt and an alkaline component are added to the O / W emulsion to deposit the ferroferric oxide nanoparticles on the surface of the kaolinite in contact with the water phase in the O / W emulsion, thereby obtaining the modified kaolinite.

4. The composite treatment of claim 3, wherein, The coupling agent is at least one of a titanate coupling agent and a silane coupling agent. The weight ratio of the kaolinite to the coupling agent is 1:0.005-0.025, preferably 1:0.01-0.

015. The hydrophobic solvent is a C4-C10 hydrocarbon solvent. 10 The hydrophobic solvent is a C4-C10 hydrocarbon solvent. Preferably, the volume ratio of the water to the hydrophobic solvent is 1:0.5-5, further 1:1-1.

5. The volume weight ratio of the total solvent of the water and the hydrophobic solvent to the kaolinite is 5-20 mL / g, further 10-15 mL / g.

5. The composite treatment of claim 3, wherein Fe 2+ , Fe 3+ in a molar ratio of 2-4:1; Preferably, the alkaline component is an alkali metal hydroxide. Preferably, the mass ratio of the kaolinite to the water-soluble ferrous salt is 2-5:

1. Preferably, the in-situ deposition temperature is 50-60℃. Preferably, the pH in the in-situ deposition process is 10-12.

6. The composition of claim 6, wherein The content of the protease is 5000-20000 U / g, and the content of the lipase is 3000-20000 U / g.

7. A method for producing the composite treatment agent according to any one of claims 1 to 6, characterized by, The components are compounded to obtain the composite treatment agent.

8. Use of the composite treatment agent according to any one of claims 1 to 6, characterized in that The composite treatment agent is used for the treatment of perchlorate wastewater.

9. Use of a composite treatment agent according to claim 8, characterized in that The perchlorate wastewater is wastewater containing ammonia nitrogen and / or nitrate nitrogen synchronously. Preferably, in the perchlorate wastewater, the concentration of the perchlorate (calculated as perchlorate) is 50-1200 mg / L, the concentration of the nitrate (calculated as nitrate nitrogen) is 50-800 mg / L, and the concentration of the ammonia nitrogen is 20-200 mg / L.

10. Use of a complexing agent as claimed in claim 8 or 9, characterized in that The dosage of the composite treatment agent in the treatment process is 100-500 mg / L. Preferably, in the process of degrading the perchlorate by the heterotrophic microorganisms, the pH is controlled at 7-7.5, the temperature is controlled at 2-35℃, and the dissolved oxygen is controlled at 0.05-0.2 mg / L. Preferably, active sludge is inoculated in the treatment process.

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