Method for deeply treating organic wastewater based on reduction-oxidation reaction interconversion circulation and application

Abstract

The invention provides a method for advanced treatment of organic wastewater based on reduction-oxidation reaction interconversion circulation and application, the method comprises the following steps: placing organic wastewater under dual-wavelength vacuum ultraviolet irradiation, adopting an aeration mode of cyclic stage input of inert gas and oxygen-containing gas, and adding inorganic sulfite when the inert gas is switched, the generation and cyclic conversion of active species in the system are regulated and controlled, and controllable multiple deep degradation is respectively carried out on organic pollutants existing in single / multi-component components in the organic wastewater and intermediate products generated in the treatment process of the organic pollutants. Through simple repeated switching of the atmosphere environment, a controllable reduction-oxidation mutual conversion circulation advanced treatment technology is effectively constructed, multiple targets of simultaneously improving the degradation rate, the mineralization rate and the dehalogenation rate are achieved, and the problem of secondary pollution of by-products is effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of organic wastewater treatment, and specifically relates to a method and application of deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle. Background Art

[0002] A large amount of organic wastewater is generated during the production and transportation of drugs or chemical products, and the composition of the organic molecule residues and their metabolites contained in them is relatively complex, usually including organic pollutants such as drug molecules (antibiotics, etc.), halogenated organic compounds, aromatic hydrocarbon compounds, and cyclic organic compounds. The continuous input and accumulation of these substances in the water environment will produce high chronic ecotoxicity to aquatic organisms, and there are irreversible negative risks to human health and ecosystems. However, due to its large molecular weight, complex organic structure and difficulty in biodegradation, it is difficult to effectively remove it with conventional water treatment processes. It is particularly noteworthy that the complex pollution system composed of multiple new organic pollutant components will greatly enhance the toxic effects on aquatic organisms, increase the complexity of the environmental migration and transformation behavior of pollutants, and increase the difficulty of deep treatment. Therefore, how to achieve efficient treatment of complex pollution under the coexistence of single / multi-difficult-to-degrade new organic pollutant components is one of the key problems in strengthening the terminal treatment capacity of new pollutants.

[0003] Traditional advanced oxidation / reduction processes combine light / electricity / heat activation methods with different types of oxidants / reductants to produce active species with strong oxidation / reduction capabilities to efficiently decompose target organic pollutants in water. Among them, the generated active species with high oxidation potential can undergo a series of oxidation reactions such as hydroxyl substitution and electron transfer with organic pollutant molecules, strengthen the ring-opening deconstruction of organic pollutants, reduce their aromaticity, and fully degrade or mineralize organic pollutants; while the generated active species with high reduction potential directly attack the carbon-halogen bond with the highly electronegative halogen atom as the center, breaking it and releasing halogen ions, thereby achieving reduction dehalogenation.

[0004] However, the research on active species-dominated antibiotic degradation technology mainly focuses on the exploration of generating a single type (oxidation or reduction) of active species. Although it can destroy part of the structure of a single pollutant to some extent, it still has certain limitations from the perspective of complete degradation. In addition, the generation and transformation process of different types of active species in a system without the addition of a catalyst lacks controllability, making it difficult for active species to maximize their own oxidation / reduction properties, affecting the treatment effect of pollutants. At the same time, the application environment of the target pollutants is single, focusing on the degradation ability of single organic pollutants and relatively high-oxidation-valence inorganic substances in a pure water environment, and it is difficult to provide accurate and reliable guidance for the deep treatment of organic wastewater pollution systems where complex organic pollutant components coexist. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides a method and application for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle. Without adding additional catalysts, the orderly cyclic generation of reduction-type active species and oxidation-type active species is effectively regulated by repeatedly switching the simple atmosphere environment, and a controllable reduction-oxidation interconversion cycle deep treatment technology is constructed to achieve the multiple goals of simultaneously improving the degradation rate, mineralization rate and dehalogenation rate, effectively solving the problem of secondary pollution of by-products.

[0006] The present invention solves the technical problem by adopting the following technical solutions:

[0007] The first object of the present invention is to provide a method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle, comprising the following steps: placing the organic wastewater under dual-wavelength vacuum ultraviolet irradiation, adopting an aeration method of cyclically inputting inert gas and oxygen-containing gas, and assisting in adding inorganic sulfite when switching to inert gas, regulating the generation and cyclic conversion of active species in the system, and controlling multiple deep degradation of organic pollutants in single / multi-component organic wastewater and intermediates generated during the treatment process.

[0008] Furthermore, the molar ratio of the amount of sulfite added before exposure to the inert gas to the organic matter content in the wastewater is 10 to 50:1.

[0009] Furthermore, the ultraviolet light uses a vacuum ultraviolet mercury lamp as a light source, and the illumination form is central irradiation.

[0010] Furthermore, the ultraviolet light source excites and releases dual-band ultraviolet light simultaneously.

[0011] Furthermore, the inert gas and the oxygen-containing gas are input into the degradation system in a phased batch cycle manner, and the aeration time ratio of the inert gas and the oxygen-containing gas in each phase is regulated according to the composition and content of the organic matter.

[0012] Furthermore, the ratio of the aeration time of the inert gas and the oxygen-containing gas in each stage is 1-9:1-9.

[0013] Furthermore, the aeration form of the inert gas and oxygen-containing gas in each stage is continuous, and the aeration form between adjacent stages is intermittent.

[0014] Furthermore, the aeration interval between adjacent stages is 0 to 10 minutes.

[0015] Furthermore, the inert gas is selected from nitrogen or argon, and the oxygen-containing gas is selected from air or oxygen.

[0016] The treatment effect of using oxygen for aeration is better than that of using air.

[0017] Furthermore, an aeration system is used for aeration, and the aeration system includes an aeration passage immersed in the wastewater, the two ends of the aeration passage are respectively connected to an aeration device and a three-way valve, a photochemical reactor is arranged between the three-way valve and the aeration passage, and the other two ends of the three-way valve are respectively connected to oxygen-containing gas and inert gas.

[0018] Furthermore, the aeration device is immersed in the wastewater.

[0019] Furthermore, the sulfite includes but is not limited to sodium sulfite, sodium bisulfite, and potassium sulfite.

[0020] The second object of the present invention is to provide an application of the above-mentioned organic wastewater treatment method in the treatment of single / multi-component new organic pollutants, wherein the single / multi-component new organic pollutants in the wastewater are any one or more of drug molecules, halogenated organic compounds, aromatic hydrocarbon compounds or cyclic organic compounds.

[0021] Furthermore, it can be used to treat organic wastewater with a pH value ranging from 2.0 to 12.0.

[0022] Compared with the prior art, the beneficial technical effects of the present invention are:

[0023] The present invention uses a dual-wavelength vacuum ultraviolet light source (VUV) with stronger photon energy to replace the traditional single-wavelength UV-C ultraviolet light source to activate sulfite ions. Based on the characteristics of dual-wavelength ultraviolet light to simultaneously photolyze water and excite sulfite ions, the system can generate hydrated electrons, hydrogen free radicals and other reducing type active species in the reduction stage, and generate sulfate free radicals, hydroxyl free radicals, superoxide free radicals and other active species with certain strong oxidizing properties in the oxidation stage based on the transformation of active species in the reduction system. It has strong controllability and anti-interference ability, and the constructed controllable reduction-oxidation synergistic degradation system enables single / multi-element new organic pollutants in organic wastewater to be completely removed under complex water environment conditions.

[0024] The method of the invention has low energy consumption, does not require the introduction of additional organic catalysts, has mild reaction conditions, and has controllable generation and conversion of active species. It only requires the use of inexpensive and readily available sulfite and a low-pressure dual-wavelength vacuum ultraviolet mercury lamp light source with low energy consumption to obtain a high removal rate and a high dehalogenation rate for new macromolecular organic pollutants in organic wastewater, and can achieve multiple conversions of intermediate products, improve the biodegradability of effluent water, effectively inhibit the negative impact of increased toxicity of degradation products on receiving water bodies, and can be expanded to be applied to the deep purification of other types of complex refractory organic pollution systems.

[0025] The present invention can have a good degradation effect under a wide pH value range of 2.0 to 12.0, thereby solving the problem of high pH requirements for wastewater treatment in the prior art, and especially solving the problem of poor degradation effect under acidic conditions.

[0026] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a graph of the degradation efficiency of Example 3 of the present invention and the unregulated comparative example 1.

[0028] Figure 2 This is a graph of the degradation efficiency under different pH conditions of Example 3 and Example 4 of the present invention.

[0029] Figure 3 This is a comparison chart of the degradation efficiency of Example 1 and Example 2 of the present invention under one stage cycle. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following embodiments are only exemplary illustrations and explanations of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are included in the scope of protection that the present invention is intended to protect.

[0031] In addition, unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0032] Example 1

[0033] A mixture of antibiotic ciprofloxacin (CIP) and norfloxacin (NOR) solutions with an initial concentration of 20 mg / L was used as simulated composite organic wastewater.

[0034] A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle, comprising the following steps:

[0035] 1) Inject 700 mL of organic wastewater into the photochemical reactor;

[0036] 2) A 10W dual-wavelength low-pressure vacuum ultraviolet mercury lamp was used as the excitation light source. After preheating for 10 minutes, it was placed in the quartz condenser tube in the center of the photochemical reactor and immersed in the polluted water body. The illumination form was central irradiation.

[0037] 3) The three-way valve gas circuit is connected to an inert gas to construct a reduction reaction environment, and a 100 mg / L sodium sulfite solution is added to the reactor at the same time. After aeration for 8 to 15 minutes under the reduction environment, the three-way valve gas circuit is switched to connect to an oxygen-containing gas, and the degradation environment is converted from a reduction reaction environment to an oxidation environment, and aeration is carried out in the oxidation environment for 8 to 15 minutes to complete a cycle of reduction-oxidation synergistic degradation reaction; in this embodiment, nitrogen is selected as the inert gas and oxygen is selected as the oxygen-containing gas.

[0038] 4) After stopping aeration for 5 minutes, repeat step 3) to achieve multiple conversions of the intermediate products. In the treatment of organic wastewater, the concentration of organic pollutants after treatment is tested by taking wastewater at regular intervals, and the degradation rate of pollutants and their intermediate products in the reaction process is calculated.

[0039] Example 2

[0040] The difference from Example 1 is that an antibiotic ciprofloxacin (CIP) solution with an initial concentration of 20 mg / L is used as the simulated organic wastewater.

[0041] Example 3

[0042] The difference from Example 1 is that an antibiotic norfloxacin (NOR) solution with an initial concentration of 20 mg / L is used as the simulated organic wastewater.

[0043] Example 4

[0044] An antibiotic norfloxacin (NOR) solution with an initial concentration of 20 mg / L was used as simulated organic wastewater, and the pH value of the wastewater was adjusted to 3.02 and 8.98, respectively. The other conditions of the two organic wastewaters were the same, and they were treated in the same way. The specific treatment method was the same as in Example 3.

[0045] Comparative Example 1

[0046] The antibiotic norfloxacin (NOR) solution with an initial concentration of 20 mg / L was used as the simulated organic wastewater.

[0047] A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle, comprising the following steps:

[0048] 1) Inject 700 mL of organic wastewater into the photochemical reactor;

[0049] 2) A 10W dual-wavelength low-pressure vacuum ultraviolet mercury lamp was used as the excitation light source. After preheating for 10 minutes, it was placed in the quartz condenser tube in the center of the photochemical reactor and immersed in the polluted water body. The illumination form was central irradiation.

[0050] 3) The three-way valve gas circuit is connected to an inert gas to construct a reduction reaction environment, and a 100 mg / L sodium sulfite solution is added to the reactor at the same time. After aeration for 8 to 15 minutes under the reduction environment, the three-way valve gas circuit is switched to connect to an oxygen-containing gas, and the degradation environment is converted from a reduction reaction environment to an oxidation environment, and aeration is carried out in the oxidation environment for 8 to 15 minutes to complete the reduction-oxidation synergistic degradation reaction; in this embodiment, nitrogen is selected as the inert gas and oxygen is selected as the oxygen-containing gas.

[0051] Experimental Example 1

[0052] See attached Figure 1 , the organic wastewater was treated according to the method of Example 3, firstly, a 5-minute photoreduction reaction was carried out, and then a 5-minute photooxidation reaction was carried out, the interval between the cycles of each stage was 5 minutes, and three cycles of reduction-oxidation synergistic degradation reaction were carried out continuously. At the same time, the organic wastewater was treated in a non-circulating system according to the method of Comparative Example 1, firstly, a 15-minute photoreduction reaction was carried out, and then a 15-minute photooxidation reaction was carried out. The two groups of wastewater after treatment were regularly tested, and the removal rates of the two groups of antibiotics are shown in the attached Figure 1 It can be seen that under the same degradation time, compared with the unregulated (non-circulating) wastewater in comparative example 1, after the auxiliary addition of sodium sulfite and circulation regulation of the present invention, the removal rate of norfloxacin increased from 87.74% to 97.26%, and the degradation rate increased by 1.68 times. The multi-stage reduction-oxidation synergistic degradation reaction of the present invention has a better removal effect on organic pollutants than the one-stage reduction-oxidation synergistic degradation reaction, and it is easy to achieve a removal rate of more than 95%.

[0053] In the reduction stage, sulfite forms hydrated electrons under the vacuum ultraviolet system. Hydrated electrons are a strong reducing agent that strengthens the dehalogenation of halogenated organic matter and improves the degradation rate and dehalogenation rate. In the oxidation stage, the degradation of organic pollutants and intermediates is attributed to the hydrated electrons and sulfite radicals generated by sulfite under reducing conditions. The transformation occurs in an oxygen-containing environment. The generated oxidative free radicals such as sulfate radicals, hydroxyl radicals, and superoxide radicals and oxidative non-radicals such as singlet oxygen are beneficial to the ring-opening deconstruction of organic molecules, and the pollutants themselves and their degradation products are destroyed at multiple levels. Therefore, the present invention can achieve the conversion from oxidation reaction to reduction reaction by supplementing sulfite while passing inert gas, that is, it can achieve multiple cycles of reduction-oxidation-reduction-oxidation...reactions. The construction of a multi-stage cyclic degradation system enhances the performance of vacuum ultraviolet degradation of organic pollutants. Compared with the non-cyclic regulation control ratio, active substances are generated cyclically in the multi-stage cyclic degradation system, and pollutants and their intermediates are transformed in stages and at multiple levels. The small molecular organic matter generated by the decomposition of organic pollutants in the cyclic system during multiple cyclic conversion processes is used as an intermediate product. The intermediate product generated in the previous cyclic conversion process can be further decomposed by reduction-oxidation reaction in the next cyclic conversion process. The functional groups with different nucleophilic / electrophilic properties carried by the intermediate product can be fully destroyed under the synergistic effect of reduction-oxidation and decomposed into small molecular organic matter with lower molecular weight. In the cyclic system of this experimental example, more than a dozen important degradation products can be decomposed and generated, making the removal of organic pollutants more thorough, thereby improving the removal efficiency of organic pollutants in the entire system and meeting the wastewater treatment requirements.

[0054] Experimental Example 2

[0055] See attached Figure 2 The pH value of the untreated wastewater in Example 3 was measured to be 6.96, and the pH values ​​of the two wastewaters in Example 4 were adjusted to 3.02 and 8.98, respectively. The three wastewaters in Example 3 and Example 4 were subjected to three cycles of reduction-oxidation synergistic degradation reaction, each cycle was aerated for 20 minutes, and the interval between each cycle was 5 minutes. The degradation efficiency is shown in the attached Figure 2 . It can be seen that the degradation efficiency of the reduction-oxidation synergistic degradation reaction in neutral and alkaline environments reaches more than 90%, and multiple cycles have little effect on the degradation efficiency. However, the degradation efficiency of wastewater in an acidic environment is only 21.63% after one cycle of reduction-oxidation synergistic degradation reaction, while the degradation efficiency reaches 95.27% after three cycles of reduction-oxidation synergistic degradation reaction, which is 4.4 times higher. The reduction-oxidation synergistic degradation system of the present invention has a wide pH adaptability range, and the degradation effect is better under pH conditions of 2 to 12, which improves the application of the system in the treatment of organic wastewater under various pH conditions.

[0056] Experimental Example 3

[0057] See attached Figure 3 , the organic wastewater was treated according to the methods of Example 1 and Example 2, wherein a 10-minute photoreduction reaction was first performed and then a 30-minute photooxidation reaction was performed, a cycle of reduction-oxidation synergistic degradation reaction was performed, and the concentration of pollutants was detected at regular intervals. Figure 3 It can be seen that compared with organic wastewater with a single pollutant, when binary composite pollutants coexist, the degradation rate of the pollutants by the synergistic degradation system has almost no change. It can be seen that the synergistic degradation system of the present invention is not affected by the type and amount of pollutants, and has good treatment capabilities for both single pollutants and multiple pollutants.

[0058] The present invention uses a dual-wavelength vacuum ultraviolet light source (VUV) to activate a sulfite system as a process template. Without adding any additional catalyst, the invention effectively regulates the orderly cyclic generation of reducing type active species and oxidizing type active species by repeatedly switching a simple atmosphere environment, thereby constructing a controllable reduction-oxidation interconversion cycle deep treatment technology, which is applied to the non-differentiated multi-level degradation of multiple new organic pollutants coexisting in a composite pollution system of organic wastewater, thereby achieving the multiple goals of simultaneously improving the degradation rate, mineralization rate and dehalogenation rate, and effectively solving the problem of secondary pollution of by-products.

[0059] The technology of the present invention combines the advantages of different types of active species degradation, uses inert gas exposure to construct a reduction system, and oxygen-containing gas exposure to construct an oxidation system. The principle of cyclic switching of aeration can regulate the mutual transformation of reduction-oxidation active species, clarifies the generation types and transformation mechanisms of active species at different stages, and at the same time proves the possibility of avoiding mutual quenching between different types of active species, and strengthens the multiple attack performance of active species on carbon-halogen bonds (CX, X=F, Cl, Br, I), aromatic rings and other functional groups, so that it can synergistically and cyclically utilize the advantages of reduction and oxidation reaction performance on the basis of green energy saving to optimize the treatment of the coexistence pollution system of multiple organic pollutant components in organic wastewater to the greatest extent. By exploring the relationship between reaction conditions and water quality parameters and degradation efficiency, the operating conditions are optimized, and the optimal process parameters are applied to enable the technology to meet the requirements of low energy consumption, harmlessness, and resource utilization of multiple antibiotic complex pollution, deepen end-of-pipe treatment, and strive to achieve the ultimate goal of coordinated control of carbon pollution on the basis of completing the directional chemical transformation of target pollutants.

[0060] Compared with the traditional ultraviolet (catalytic) degradation method, this method is mainly used for the deep treatment of single / multi-element new organic pollutant (complex) pollution system in organic wastewater. By establishing a cyclic conversion mode of reduction-oxidation degradation system, the molecular structures of multiple types of coexisting organic pollutants with electrophilic or nucleophilic properties are destroyed separately, and the intermediate products are degraded for the second time, thereby reducing the generation of harmful by-products, improving the biochemical utilization performance of the final reaction system, and suppressing the risk of secondary pollution of the receiving effluent.

[0061] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0062] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle, It is characterized in that The method comprises the following steps: placing the organic wastewater under dual-wavelength vacuum ultraviolet irradiation, adopting an aeration method of circulating and staged input of inert gas and oxygen-containing gas, and assisting in the addition of inorganic sulfite when switching to inert gas, regulating the generation and cyclic conversion of active species in the system, and controlling multiple deep degradation of organic pollutants in single / multi-component organic wastewater and intermediate products generated during the treatment process.

2. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle as claimed in claim 1, Features: The molar ratio of the amount of sulfite added before exposure to the inert gas to the organic matter content in the wastewater is 10 to 50:

1.

3. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle as claimed in claim 1, Features: The ultraviolet light source excites and releases dual-band ultraviolet light simultaneously.

4. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle as claimed in claim 1, Features: Inert gas and oxygen-containing gas are input into the degradation system in a phased batch cycle.

5. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle as claimed in claim 4, Features: The aeration form of inert gas and oxygen-containing gas in each stage is continuous, and the aeration form between adjacent stages is intermittent.

6. A method for deep treatment of organic wastewater based on reduction-oxidation reaction interconversion cycle as claimed in claim 5, Features: The aeration interval between adjacent stages is 0 to 10 minutes.

7. An application of the organic wastewater treatment method according to any one of claims 1 to 6 in the treatment of mono- / multi-organic polluted wastewater, wherein the mono- / multi-organic pollutants in the wastewater are any one or more of drug molecules, halogenated organic compounds, aromatic hydrocarbon compounds or cyclic organic compounds.

8. The use as claimed in claim 7, Features: It can be used to treat organic wastewater with a pH value ranging from 2.0 to 12.0.

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