Method and device for purifying printing and dyeing wastewater based on TAPB-DMTA COF Fenton-like synergistic bacteria and algae

Abstract

The invention relates to the technical field of sewage treatment, in particular to a method and device for purifying printing and dyeing wastewater based on TAPB-DMTA COF Fenton-like synergistic bacteria and algae. According to the specific technical scheme, the printing and dyeing wastewater purification method comprises the following steps that 1, printing and dyeing wastewater is introduced into a photocatalytic Fenton-like reactor, porosity-modified photocatalysts TAPB-DMTA COF and H2O2 are added into the photocatalytic Fenton-like reactor, a baffle plate is arranged in the photocatalytic Fenton-like reactor, the angle of the baffle plate is 30-45 degrees, and the angle of the baffle plate is 30-45 degrees; a first illumination module is arranged outside the photocatalytic Fenton-like reactor; and (2) introducing the wastewater treated in the step (1) into an algal-bacterial symbiotic SNAD reactor, and adding a photocatalyst and a multi-walled carbon nanotube into the algal-bacterial symbiotic SNAD reactor. The photocatalytic Fenton-like reactor disclosed by the invention takes porosity modified TAPB-DMTA COF as a photocatalyst aiming at dyestuff which is difficult to degrade, so that complete degradation of the dyestuff is realized. For ammonia nitrogen pollutants, the bacterial-algae symbiotic SNAD reactor cancels traditional mechanical aeration, the microbial extracellular electron acquisition capability is optimized through a biological enhancer, and efficient and green removal of total nitrogen can be realized without adding an organic carbon source.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and in particular to a method and device for purifying printing and dyeing wastewater based on TAPB-DMTA COF-type Fenton-like synergistic bacteria and algae. Background Art

[0002] Every year, a large amount of synthetic dyes are produced worldwide for printing and dyeing, and part of them are discharged with wastewater. Printing and dyeing wastewater has the characteristics of large water volume, high content of organic pollutants, deep chroma, high alkalinity, and large changes in water quality. Therefore, this type of wastewater is difficult to be effectively treated by conventional wastewater treatment methods, especially decolorization. As a highly promising advanced oxidation process, Fenton-like reaction has been widely used in the treatment of refractory organic dyes. Fenton-like catalysts activate hydrogen peroxide (H2O2), peroxymonosulfate (PMS) or peroxydisulfide (PDS) to produce hydroxyl radicals (·OH), sulfate radicals (SO4 ·- ), superoxide radicals (O2 ·- ) or singlet oxygen ( 1 O2) can oxidize organic pollutants and even completely mineralize them into CO2 and H2O.

[0003] Free radical-mediated heterogeneous catalytic oxidation is the core of dye degradation, however, a single form or free radicals of the same nature are usually far from sufficient to meet the entire catalytic reaction process. Advanced oxidation mediated by hydroxyl radicals (·OH) has been shown to be difficult to completely remove most organic pollutants in printing and dyeing wastewater, mainly aromatic dyes. The main reason is that a refractory key intermediate, which has so far been generally considered to be benzoquinone, usually accumulates in the system, resulting in low overall mineralization efficiency. The original aromatic molecule can be attacked by ·OH and converted into benzoquinone, but the formed benzoquinone intermediate is difficult to be further oxidized by ·OH; therefore, the entire degradation process of advanced oxidation terminates at this stage. Once discharged into the environment, the residual benzoquinone will have an irreversible impact on the environment and may threaten human health due to its high toxicity. O2 ·- It exhibits high selectivity for electron-rich or electron-deficient species and can react smoothly with benzoquinone and further convert it into small molecules. Therefore, the regulation and matching of free radical types are crucial for the complete removal of ubiquitous aromatic dyes.

[0004] In addition, printing and dyeing wastewater contains a high concentration of ammonia nitrogen. Some reactive dyes and direct dyes contain nitrogen-containing functional groups such as amino groups (-NH2). These nitrogen-containing substances will enter the wastewater during the dyeing process. After the wastewater undergoes an advanced oxidation process, the oxidative degradation of nitrogen-containing functional groups will further increase the ammonia nitrogen concentration in the wastewater. Biological denitrification relies on the natural transformation process of microorganisms and has low operating costs. However, traditional denitrification strategies require a lot of energy, especially aeration, and the denitrification effect is limited by the carbon source of the influent. Therefore, efficient and energy-saving processes are needed to improve the denitrification effect and reduce wastewater treatment costs. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present invention provides a method and device for purifying printing and dyeing wastewater based on TAPB-DMTA COF-type Fenton-like synergistic bacteria and algae.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention discloses a method for purifying printing and dyeing wastewater, comprising the following steps:

[0008] (1) Printing and dyeing wastewater is introduced into a photocatalytic Fenton reactor, into which porosity-modified photocatalysts TAPB-DMTA COF and H2O2 are added, a baffle is provided inside the photocatalytic Fenton reactor, and the baffle angle is 30-45 degrees, and a first illumination module is provided outside the photocatalytic Fenton reactor;

[0009] (2) The wastewater treated in step (1) is passed into a bacteria-algae symbiotic SNAD reactor, wherein the bacteria-algae symbiotic SNAD reactor is inoculated with short-cut nitrification sludge and Chlorella vulgaris, and a photocatalyst and multi-walled carbon nanotubes are added into the bacteria-algae symbiotic SNAD reactor.

[0010] Preferably, the photocatalyst TAPB-DMTA COF is prepared using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as raw materials and an acetic acid aqueous solution as a catalyst.

[0011] Preferably, the preparation process of the photocatalyst TAPB-DMTA COF is as follows: 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde are dissolved in acetonitrile in sequence, with a stirring speed of 200-300 r / min; the ultrasonic power is 100-150 W, the ultrasonication is performed for 60 s, the interval is 60 s, and the upper limit of the ultrasonication temperature is 35°C; the ultrasonication is performed for 30-60 min respectively until all the solids are dissolved, and then an acetic acid aqueous solution is added to obtain the product.

[0012] Preferably, the molar ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-dimethoxyterephthalaldehyde is 1:1-1.5, the concentration of the acetic acid aqueous solution is 1.0-12.0 mol / L, and the volume ratio of the acetic acid aqueous solution to acetonitrile is 0.2-0.3.

[0013] Preferably, in step (1), the dosage of the photocatalyst TAPB-DMTA COF is 50-200 mg / L, the stirring speed is 500-700 r / min, and the illumination intensity of the first illumination module is 0.7-0.8×10 4 lux, H2O2 addition concentration is 0.1~0.5mM, and reflux ratio is 5~10.

[0014] Preferably, a plurality of modular filler components are provided inside the bacteria-algae symbiotic SNAD reactor, and a second lighting module is provided outside the bacteria-algae symbiotic SNAD reactor.

[0015] Preferably, the illumination intensity of the second illumination module is 5000-10000 lux.

[0016] Preferably, the specific process of inoculating the short-cut nitrification sludge and Chlorella in the bacteria-algae symbiotic SNAD reactor is as follows: adding 1-2 g / L of short-cut nitrification sludge and 1-2 g / L of oxygen-ammonia oxidation sludge, and controlling the dissolved oxygen to be less than 1 mg / L during the reaction; inoculating Chlorella after the total nitrogen removal rate reaches 85%, each inoculation concentration is 1-2 g / L, inoculated once every two hydraulic retention times, and repeated 5-10 times; after inoculating Chlorella, gradually reducing the mechanical aeration, reducing it by 10-20 ml / min every two hydraulic retention times, until the oxygen production of Chlorella completely replaces the mechanical aeration.

[0017] Preferably, in step (2), the dosage of the photocatalyst is 100-300 mg / L, and the dosage of the multi-walled carbon nanotubes is 50-100 mg / L.

[0018] Accordingly, a purification device based on the printing and dyeing wastewater purification method includes a photocatalytic Fenton reactor and a bacteria-algae symbiotic SNAD reactor connected to the photocatalytic Fenton reactor through a pipeline, a first illumination module is provided outside the photocatalytic Fenton reactor, a baffle is provided inside the photocatalytic Fenton reactor, and a first stirring mechanism is provided outside the photocatalytic Fenton reactor 1;

[0019] A plurality of modular filler assemblies are provided in the bacteria-algae symbiotic SNAD reactor, and the filler assemblies are vertically arranged in the bacteria-algae symbiotic SNAD reactor; a second illumination module is provided outside the bacteria-algae symbiotic SNAD reactor, and a second stirring mechanism is provided in the bacteria-algae symbiotic SNAD reactor.

[0020] The present invention has the following beneficial effects:

[0021] 1. The present invention targets refractory dyes. The photocatalytic Fenton reactor uses porosity-modified (i.e., different porosities) TAPB-DMTA COF as a photocatalyst. The modified COF can complete the conversion of ·OH and O2 in the reaction system. ·- The regulation and combination of the two technologies effectively overcomes the degradation limitations of the aromatic intermediate benzoquinone, achieving complete degradation of the dye. For ammonia nitrogen pollutants, the bacteria-algae symbiotic SNAD reactor eliminates traditional mechanical aeration and optimizes the microbial extracellular electron acquisition capacity through bioaugmentation, achieving efficient and green removal of total nitrogen without the addition of an organic carbon source.

[0022] 2. The photocatalytic Fenton reactor disclosed in the present invention uses porosity-modified TAPB-DMTA COF as a photocatalyst to regulate and match OH and O2 in the photocatalytic Fenton reaction. ·- , achieving effective and complete dye removal, with a COD removal efficiency of 90-95%. The bacteria-algae symbiotic SNAD reactor further removes organic matter from the water, with a COD removal efficiency of 50-60%. It also removes total nitrogen from the water, with a total nitrogen removal efficiency of 95%.

[0023] 3. The photocatalytic Fenton reactor disclosed in the present invention can achieve deep and complete removal of refractory substances (such as aromatic dyes) in printing and dyeing wastewater after biological treatment. ·- The types of COF radicals after porosity modification (·OH and O2 ·- ) are adjusted and matched to eliminate the highly toxic and difficult-to-degrade key intermediate benzoquinone, thereby achieving effective and complete removal of aromatic dyes.

[0024] 4. Low-porosity TAPB-DMTA COF exhibits excellent photocatalytic activity under low-power light sources. Previous studies generally used high-power light sources to simulate sunlight (6-10×10 4 To obtain high-energy light sources (4900 lux), photocatalysis requires high-energy ultraviolet light or high-pressure mercury lamps to effectively remove organic matter. Low-porosity TAPB-DMTA COF can catalyze a Fenton-like reaction under ultra-low-power LED light (4900 lux) to achieve efficient removal of organic dyes. This low-cost, environmentally friendly, and easily industrializable material offers the potential for all-weather catalytic green pollution control driven by ultra-low energy consumption and visible light.

[0025] 5. The SNAD wastewater treatment technology combines bacteria and algae with a low energy consumption and high efficiency. The oxygen required by ammonia-oxidizing bacteria is entirely provided by the photosynthesis of the algae, eliminating the need for additional aeration. Compared to traditional denitrification processes, the SNAD reactor reduces aeration energy consumption and carbon source supply by 100%, achieving low-energy, high-efficiency carbon and nitrogen removal.

[0026] 6. Adding TAPB-DMTA COF and multi-walled carbon nanotubes enhances the denitrification performance of bacteria and algae. Photoexcited TAPB-DMTA COF generates photogenerated electrons that enhance the algae's light utilization efficiency and oxygen production, ensuring a continuous oxygen supply for subsequent denitrification. Multi-walled carbon nanotubes, acting as nanowires, enhance the transfer of photogenerated electrons and interspecies electrons between bacteria and algae, increasing their ability to acquire extracellular electrons. This provides functional microorganisms with more reducing power for energy metabolism, helping to strengthen the denitrification performance of the SNAD reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the device for purifying printing and dyeing wastewater based on TAPB-DMTA COF-like Fenton-like synergistic bacteria and algae;

[0028] Figure 2 is the SEM image of the original TAPB-DMTA COF;

[0029] Figure 3 This is the SEM image of low-porosity TAPB-DMTA COF;

[0030] Figure 4 is the powder X-ray diffraction pattern;

[0031] Figure 5 is the nitrogen adsorption isotherm at 77K;

[0032] Figure 6 (A) UV-Vis DRS spectrum and estimated band gap (inset) and (B) XPS spectrum;

[0033] Figure 7 This is a diagram of a free radical trapping experiment;

[0034] Figure 8 This is the experimental diagram of the 5-cycle degradation of low-porosity TAPB-DMTA COF;

[0035] Figure 9 is the liquid chromatography-mass spectrum of benzoquinone (m / z 108.3) in the reaction system;

[0036] In the figure: a photocatalytic Fenton reactor 1, a bacteria-algae symbiotic SNAD reactor 2, a first water inlet pump, a photocatalyst TAPB-DMTA COF 4, a first illumination module 5, a drug inlet pump 6, a first stirring mechanism 7, a reflux pump 8, a baffle 9, a second water inlet pump 10, a second stirring mechanism 11, a filler assembly 12, a second illumination module 13, and a bio-enhancer 14. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0039] The present invention discloses a method for purifying printing and dyeing wastewater, which is characterized by comprising the following steps:

[0040] (1) The printing and dyeing wastewater is passed into the photocatalytic Fenton reactor 1 to remove the refractory organic matter in the printing and dyeing wastewater. The porosity-modified photocatalyst TAPB-DMTA COF and H2O2 are added to the photocatalytic Fenton reactor 1. The added photocatalyst TAPB-DMTA COF has the characteristics of dye-specific and efficient removal, effectively breaking the degradation limit of the aromatic intermediate benzoquinone and achieving complete degradation of the dye. The photocatalytic Fenton reactor is provided with a baffle to increase the reaction process, ensure the full contact between the photocatalyst TAPB-DMTA COF and the wastewater and achieve effective retention of the catalyst by gravity sedimentation. The baffle angle is 30-45°. The photocatalytic Fenton reactor is provided with a first illumination module 5 outside the photocatalytic Fenton reactor. The illumination intensity of the first illumination module is 0.7-0.8×10 4 lux to increase the light source required for light collection; the dosage of the photocatalyst TAPB-DMTA COF is 50-200 mg / L, the stirring speed is 500-700 r / min, the H2O2 addition concentration is 0.1-0.5 mM, and the reflux ratio is 5-10.

[0041] (2) The wastewater treated in step (1) is passed into a bacteria-algae symbiotic SNAD reactor 2 (i.e., a bacteria-algae symbiotic synchronous short-term nitrification, anaerobic ammonium oxidation, and denitrification (SNAD) reactor), wherein the bacteria-algae symbiotic SNAD reactor is inoculated with short-term nitrification sludge and Chlorella vulgaris, wherein the sludge includes Chlorella vulgaris, ammonia-oxidizing bacteria, anaerobic ammonium-oxidizing bacteria, and denitrifying bacteria, and nitrogen in the printing and dyeing wastewater is removed without aeration and without the addition of a carbon source; during the operation of the bacteria-algae symbiotic SNAD reactor, a bio-enhancer 14 is added and attached to the biofilm, wherein the bio-enhancer 14 includes a photocatalyst and multi-walled carbon nanotubes, which enhance the transfer of photogenerated electrons and interspecies electrons between bacteria and algae, enhance the ability of bacteria and algae to obtain extracellular electrons, and improve the denitrification performance of the bacteria-algae SNAD. The photocatalyst is a common TAPB-DMTA COF. The SNAD reactor is equipped with multiple modular packing assemblies 12, and a second illumination module 13 is installed outside the reactor. The illumination intensity of the second illumination module 13 is 5,000 to 10,000 lux. The dosage of the photocatalyst is 100 to 300 mg / L, and the dosage of the multi-walled carbon nanotubes is 50 to 100 mg / L.

[0042] Furthermore, the photocatalyst TAPB-DMTA COF is prepared using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as raw materials and an acetic acid aqueous solution as a catalyst.

[0043] Specifically, the preparation process of the photocatalyst TAPB-DMTA COF is as follows: 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde are dissolved in acetonitrile in sequence, with a stirring speed of 200-300 r / min; ultrasonic power is 100-150 W, ultrasonication is performed for 60 seconds, with an interval of 60 seconds, and the upper limit of ultrasonication temperature is 35°C; ultrasonication is performed for 30-60 minutes respectively until all solids are dissolved, and then an acetic acid aqueous solution is added to obtain the product.

[0044] The molar ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-dimethoxyterephthalaldehyde is 1:1-1.5, the concentration of the acetic acid aqueous solution is 1.0-12.0 mol / L, and the volume ratio of the acetic acid aqueous solution to acetonitrile is 0.2-0.3.

[0045] Furthermore, photocatalytic TAPB-DMTA COF materials with different porosities can be prepared by changing the concentration of acetic acid aqueous solution. As a preferred solution, the porosity-modified photocatalyst TAPB-DMTA COF has the best Fenton-like dye removal performance when the acetic acid aqueous solution is 12M.

[0046] Furthermore, the specific process of inoculating the short-cut nitrification sludge and Chlorella in the bacteria-algae symbiotic SNAD reactor is as follows: adding 1-2 g / L of short-cut nitrification sludge and 1-2 g / L of oxygen-ammonia oxidation sludge, and controlling the dissolved oxygen to be less than 1 mg / L during the reaction; inoculating Chlorella after the total nitrogen removal rate reaches 85%, each inoculation concentration is 1-2 g / L, inoculated once every two hydraulic retention times (HRT), and repeated 5-10 times; after inoculating Chlorella, gradually reduce the mechanical aeration, and reduce it by 10-20 ml / min every two hydraulic retention times (HRT) until the oxygen production of Chlorella completely replaces the mechanical aeration.

[0047] The present invention discloses a purification device based on a printing and dyeing wastewater purification method, comprising a photocatalytic Fenton reactor 1 and a bacteria-algae symbiotic SNAD reactor 2 connected thereto via a pipeline. A second water inlet pump 10 is provided on the pipeline. A first illumination module 5 is provided outside the photocatalytic Fenton reactor 1 to increase the light source required for light collection. A baffle 4 is provided inside the photocatalytic Fenton reactor 1, with an angle of 30 to 45 degrees to ensure sufficient contact between the photocatalyst TAPB-DMTA COF and the wastewater, and to achieve effective retention of the catalyst through gravity sedimentation. A first stirring mechanism 7, such as a magnetic stirring mechanism, is provided outside the photocatalytic Fenton reactor 1.

[0048] Furthermore, a feed pump 6 is provided outside the photocatalytic Fenton reactor 1 to enable the addition of H2O2. The photocatalytic Fenton reactor 1 is also provided with a reflux pump 8, the inlet and outlet of which are respectively connected to the photocatalytic Fenton reactor 1 and arranged near the top and bottom thereof. In combination with a first stirring mechanism 7, this ensures sufficient contact between the photocatalyst TAPB-DMTACOF and the wastewater, and a baffle is provided to increase the reaction flow.

[0049] Furthermore, a plurality of modular filler assemblies 12 are provided in the bacteria-algae symbiotic SNAD reactor 2, and the filler assemblies 12 are vertically arranged in the bacteria-algae symbiotic SNAD reactor 2; a second illumination module 13 is provided outside the bacteria-algae symbiotic SNAD reactor, and a second stirring mechanism 11 is provided in the bacteria-algae symbiotic SNAD reactor 2 to ensure that the wastewater is in full contact with the filler assembly (such as sponge filler). It should be noted that the filler in the filler assembly can be a sponge. As one embodiment, the sponge filler is a cube with a side length of 2 to 3 cm, the volume filling ratio of the sponge filler is 30 to 50%, and the sponge filler is equidistantly fixed vertically in the bacteria-algae symbiotic SNAD reactor 2.

[0050] The present invention will be further described below with reference to specific embodiments.

[0051] Example 1

[0052] Synthesis of photocatalyst TAPB-DMTA COF:

[0053] 1,3,5-tris(4-aminophenyl)benzene (TAPB, 353 mg, 1 mmol) and 2,5-dimethoxyterephthalaldehyde (DMTA, 293 mg, 1.5 mmol) were added to a flask containing 240 mL of acetonitrile and ultrasonicated at room temperature for 60 min to completely dissolve the monomers. Then, 48 mL of 6 M acetic acid solution was added to obtain a mixture. After the mixture was allowed to stand at 25°C for 12 h, the yellow precipitate was collected by centrifugation and washed three times with ACN and ultrapure water respectively. The original TAPB-DMTA COF was obtained by vacuum drying at 80°C for 24 h. The product prepared above was characterized by SEM. Figure 2 It can be seen that the surface of the prepared material is rough and sea urchin-like, forming a hierarchical porous structure, which can provide abundant channels for organic pollutants.

[0054] Example 2

[0055] Synthesis of low-porosity photocatalyst TAPB-DMTA COF:

[0056] 1,3,5-tris(4-aminophenyl)benzene (TAPB, 353 mg, 1 mmol) and 2,5-dimethoxyterephthalaldehyde (DMTA, 293 mg, 1.5 mmol) were added to a flask containing 240 mL of acetonitrile and ultrasonicated at room temperature for 60 min to completely dissolve the monomers. Then, 48 mL of 12 M acetic acid solution was added to obtain a mixture. After the mixture was allowed to stand at 25°C for 12 h, the yellow precipitate was collected by centrifugation and washed three times with ACN and ultrapure water respectively. Low porosity TAPB-DMTA COF was obtained by vacuum drying at 80°C for 24 h. The product prepared above was characterized by SEM. Figure 3 It can be seen that the prepared material has a morphology similar to that of the original TAPB-DMTA COF and tends to be more spherical.

[0057] The physicochemical properties of the original TAPB-DMTA COF prepared in Example 1 and the low-porosity TAPB-DMTA COF prepared in Example 2 were characterized. The powder X-ray diffraction characterization results showed that TAPB-DMTA COF showed a characteristic peak at 2θ (2.6), and the low-porosity TAPB-DMTA COF had a high crystallinity ( Figure 4 Nitrogen adsorption analysis was performed at 77 K to determine the porosity of 6M COF and low-porosity TAPB-DMTA COF ( Figure 5 The pore sizes of the pristine TAPB-DMTA COF and the low-porosity TAPB-DMTA COF were calculated to be 3.1 nm and 2.7 nm, respectively, based on nonlocal density functional theory (NLDFT).

[0058] The optical and electrical properties of the original TAPB-DMTA COF prepared in Example 1 and the low-porosity TAPB-DMTA COF prepared in Example 2 were tested. Figure 6 As shown. Due to the conjugated structure of TAPB-DMTA COF, both the original TAPB-DMTA COF and the low-porosity TAPB-DMTA COF have a wide visible light absorption range (around 680 nm), corresponding to narrow band gaps of 1.51 eV and 1.47 eV, respectively ( Figure 6 A), the reduction of the band gap is conducive to increasing the absorption range. The valence band electron positions (VB) of the original TAPB-DMTA COF and the low-porosity TAPB-DMTA COF were determined by valence band X-ray photoelectron spectroscopy (VBXPS) to be 1.37e and 1.09eV, respectively ( Figure 6 B); their conduction bands (CB) are -0.14eV and -0.38eV respectively. Compared with the original TAPB-DMTACOF, the CB position of the low-porosity TAPB-DMTA COF is higher than that of O2 reduced to O2 ·- The electrode potential of -0.33 eV is much more negative, which indicates that the photoexcited electrons will be captured by the dissolved O2 to generate O2 ·- , directly oxidize organic molecules in aqueous solution. ·OH exists in the aqueous phase for a very short time (~10us), which limits its transfer from the generation site to the target organic matter, while O2 ·- It can stay in the system for hundreds of seconds, which means that porosity modification can increase the contact between ROS and pollutants in the reaction system, thereby enhancing the degradation efficiency of organic matter. In addition, studies have shown that O2 ·- Free radicals are the main active species in the photodegradation of liquid aromatic dyes. At the same time, the reduction of the CB position is thermodynamically favorable for the single-electron reduction of O2. In contrast, the CB energy level of the original TAPB-DMTACOF is only -0.14eV, which cannot excite O2. ·- and 1 Therefore, the change of ROS species in the Fenton-like reaction system mediated by the photocatalysis of low-porosity TAPB-DMTA COF is beneficial to improving the removal efficiency of dyes.

[0059] Example 3

[0060] Catalytic degradation tests were performed on the original TAPB-DMTA COF prepared in Example 1 and the low-porosity TAPB-DMTA COF prepared in Example 2.

[0061] 1. Photocatalyst TAPB-DMTA COF was used to degrade malachite green in a liquid environment.

[0062] A 20 mg / L malachite solution was prepared and placed in a photocatalytic Fenton reactor. 200 mg / L TAPB-DMTACOF was added and pre-adsorbed for 60 min under dark conditions. A low-power LED lamp was used as the light source. H2O2 was added and tert-butyl alcohol (TBA) and hydroquinone (pBQ) were used to remove OH and HO2 in the reaction system. · / O2 ·- Free radicals were captured and the degradation effect was as follows Figure 7 As shown. In the original TAPB-DMTA COF-mediated oxidation system, ·OH plays a dominant role in the degradation of malachite green, while in the low-porosity TAPB-DMTA COF reaction system, HO2 · / O2 ·- The contribution rate to organic matter removal is higher than that of ·OH. Therefore, the TAPB-DMTA COF-mediated reaction system after porosity modification tends to generate HO2 with a longer lifespan. · / O2 ·- , while HO2 · / O2 ·- Can further 1 O2 conversion. Relative to HO2 · / O2 ·- and OH, 1 O2 can also play a role in the chain initiation and chain growth reaction of aromatic organic dyes. Therefore, porosity modification realizes the conversion of ·OH in the reaction system to long-lived HO2 · / O2 ·- and 1 The conversion of O2 is conducive to the efficient removal of malachite green by the low-porosity TAPB-DMTA COF photocatalytic Fenton-like system.

[0063] 2. Cyclic degradation effect of photocatalyst TAPB-DMTA COF

[0064] The photocatalyst TAPB-DMTA COF was used to degrade malachite green in a liquid environment.

[0065] A 20 mg / L malachite solution was prepared and placed in a photocatalytic Fenton reactor. 200 mg / L low-porosity TAPB-DMTA COF was added. The solution was pre-adsorbed for 60 min in the dark. A low-power LED lamp was used as the light source. H2O2 was added. The degradation effect after 5 cycles was as follows: Figure 8 After 5 consecutive cycles of testing, the photocatalytic Fenton-like system mediated by low-porosity TAPB-DMTA COF maintained a removal rate of about 95% for malachite green, indicating that low-porosity TAPB-DMTA COF has the stability and applicability for repeated use.

[0066] 3. After the photocatalyst TAPB-DMTA COF degraded malachite green in a liquid environment, the degradation intermediates of malachite green in the Fenton-like system were analyzed by liquid chromatography-mass spectrometry. The liquid chromatography-mass spectrometry results showed that no significant enrichment of benzoquinone intermediates was found in the Fenton-like system mediated by 12M COF photocatalysis ( Figure 9 ). Therefore, the photocatalytic activity of ·OH and O2 in the Fenton-like system mediated by 12M COF is ·- The coexistence of these two agents can achieve effective and complete removal of aromatic dyes, ensuring the safety of water quality for wastewater reuse or discharge.

[0067] Example 4

[0068] The micro-algae symbiotic SNAD reactor is equipped with multiple modular packing assemblies. A second lighting module is installed outside the SNAD reactor. The illumination intensity of the second lighting module is 5000-10000 lux. The sponge packing is a cube with a side length of 2-3 cm, and the volume filling ratio of the sponge packing is 30-50%. The sponge packing is evenly spaced and vertically fixed in the SNAD reactor.

[0069] The SNAD reactor is inoculated with 1-2 g / L of short-range nitrification sludge and 1-2 g / L of oxygen-ammonia oxidation sludge, with dissolved oxygen controlled below 1 mg / L. After achieving a total nitrogen removal rate of 85%, Chlorella vulgaris is inoculated at a concentration of 1-2 g / L, repeated 5-10 times every two hydraulic retention times (HRTs). After inoculation, mechanical aeration is gradually reduced by 10-20 ml / min every two HRTs until oxygen production by Chlorella completely replaces mechanical aeration.

[0070] During the operation of the bacteria-algae symbiotic SNAD reactor, a bioenhancer was added and adhered to the biofilm. The bioenhancer consisted of a photocatalyst and carbon nanowires. The photocatalyst was a standard TAPB-DMTA COF, and the carbon nanowires were multi-walled carbon nanotubes. The TAPB-DMTA COF dosage was 200 mg / L, and the multi-walled carbon nanotube dosage was 50 mg / L. The denitrification performance of the bacteria-algae symbiotic SNAD reactor during the mechanical aeration phase and during the Chlorella oxygen production phase are shown in Tables 1 and 2 below.

[0071] Table 1 Denitrification performance of the bacterial-algal symbiotic SNAD reactor during the mechanical aeration operation phase

[0072]

[0073] Table 2 Denitrification performance of Chlorella during oxygen production operation in the SNAD reactor of bacteria-algae symbiosis

[0074]

[0075] Example 5

[0076] This embodiment provides a method for treating printing and dyeing wastewater from a certain enterprise by combining a photocatalytic Fenton reactor with a bacteria-algae symbiotic SNAD reactor. The treatment parameters of the bacteria-algae symbiotic SNAD reactor are the same as those in Example 4, and the treatment parameters of the photocatalytic Fenton reactor refer to the parameters involved in the purification method disclosed in the present invention. The photocatalyst used is the low-porosity TAPB-DMTA COF prepared in Example 2. The dosage of low-porosity TAPB-DMTA COF in the photocatalytic Fenton reactor is 150 mg / L, the concentration of hydrogen peroxide is 0.5 mM, and the reflux ratio is 5. The inlet and outlet water quality of the printing and dyeing wastewater of a certain enterprise is shown in Table 3. The water volume of the printing and dyeing wastewater is 3500 m 3 / d.

[0077] Table 3 Water quality of inlet and outlet water of printing and dyeing wastewater of a certain enterprise

[0078]

[0079] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for purifying printing and dyeing wastewater, characterized in that: The following steps are involved: (1) Printing and dyeing wastewater is introduced into a photocatalytic Fenton reactor (1), into which porosity-modified photocatalysts TAPB-DMTA COF and H2O2 are added, a baffle (9) is arranged inside the photocatalytic Fenton reactor, and the angle of the baffle (9) is 30 to 45 degrees, and a first illumination module (5) is arranged outside the photocatalytic Fenton reactor; (2) The wastewater treated in step (1) is passed into a bacteria-algae symbiotic SNAD reactor (2), wherein the bacteria-algae symbiotic SNAD reactor (2) is inoculated with short-range nitrification sludge and Chlorella vulgaris, and a photocatalyst and multi-walled carbon nanotubes are added into the bacteria-algae symbiotic SNAD reactor (2).

2. A method for purifying printing and dyeing wastewater according to claim 1, characterized in that: The photocatalyst TAPB-DMTA COF is prepared by using 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde as raw materials and acetic acid aqueous solution as catalyst.

3. A method for purifying printing and dyeing wastewater according to claim 2, characterized in that: The preparation process of the photocatalyst TAPB-DMTA COF is as follows: 1,3,5-tris(4-aminophenyl)benzene and 2,5-dimethoxyterephthalaldehyde are dissolved in acetonitrile in sequence, the stirring speed is 200-300r / min; the ultrasonic power is 100-150W, the ultrasonic is performed for 60s, the interval is 60s, and the upper limit of the ultrasonic temperature is 35°C; the ultrasonic is performed for 30-60min respectively until the solid is completely dissolved, and then an acetic acid aqueous solution is added to obtain the photocatalyst TAPB-DMTA COF.

4. A method for purifying printing and dyeing wastewater according to claim 3, characterized in that: The molar ratio of 1,3,5-tris(4-aminophenyl)benzene to 2,5-dimethoxyterephthalaldehyde is 1:1-1.5, the concentration of the acetic acid aqueous solution is 1.0-12.0 mol / L, and the volume ratio of the acetic acid aqueous solution to acetonitrile is 0.2-0.

3.

5. A method for purifying printing and dyeing wastewater according to any one of claims 1 to 4, characterized in that: In step (1), the dosage of the photocatalyst TAPB-DMTA COF is 50-200 mg / L, the stirring speed is 500-700 r / min, and the illumination intensity of the first illumination module (5) is 0.7-0.8×10 4 lux, H2O2 concentration is 0.1~0.5mM, and reflux ratio is 5~10.

6. A method for purifying printing and dyeing wastewater according to claim 1, characterized in that: A plurality of modular filler components (12) are arranged inside the bacteria-algae symbiotic SNAD reactor (2), and a second illumination module (13) is arranged outside the bacteria-algae symbiotic SNAD reactor.

7. A method for purifying printing and dyeing wastewater according to claim 6, characterized in that: The illumination intensity of the second illumination module (13) is 5000-10000 lux.

8. A method for purifying printing and dyeing wastewater according to claim 1, characterized in that: The specific process of inoculating the short-cut nitrification sludge and Chlorella in the bacteria-algae symbiotic SNAD reactor (2) is as follows: adding 1-2 g / L of short-cut nitrification sludge and 1-2 g / L of oxygen-ammonia oxidation sludge, and controlling the dissolved oxygen to be lower than 1 mg / L during the reaction; inoculating Chlorella after the total nitrogen removal rate reaches 85%, each inoculation concentration is 1-2 g / L, inoculating once every 2 hydraulic retention times, and repeating 5-10 times; after inoculating Chlorella, gradually reducing mechanical aeration, reducing it by 10-20 ml / min every 2 hydraulic retention times, until the oxygen production of Chlorella completely replaces the mechanical aeration.

9. A method for purifying printing and dyeing wastewater according to claim 1, characterized in that: In step (2), the dosage of the photocatalyst is 100-300 mg / L, and the dosage of the multi-walled carbon nanotubes is 50-100 mg / L.

10. A purification device based on the method for purifying printing and dyeing wastewater according to any one of claims 1 to 9, characterized in that: The invention comprises a photocatalytic Fenton reactor (1) and a bacteria-algae symbiotic SNAD reactor (2) connected to the photocatalytic Fenton reactor (1) through a pipeline, wherein the photocatalytic Fenton reactor (1) and the bacteria-algae symbiotic SNAD reactor (2) are respectively provided with a lighting module (5) outside, the photocatalytic Fenton reactor (1) is provided with a baffle (4) inside, and the photocatalytic Fenton reactor (1) is provided with a first stirring mechanism (7) outside; A plurality of modular filler assemblies (12) are arranged in the bacteria-algae symbiotic SNAD reactor (2), and the filler assemblies (12) are arranged vertically in the bacteria-algae symbiotic SNAD reactor (2); a second illumination module (13) is arranged outside the bacteria-algae symbiotic SNAD reactor, and a second stirring mechanism (11) is arranged in the bacteria-algae symbiotic SNAD reactor (2).

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