Sewage treatment system and method for photocatalytic coupling biological treatment

Abstract

The invention relates to the technical field of sewage treatment, and discloses a sewage treatment system and method for photocatalytic coupling biological treatment.The sewage treatment system for photocatalytic coupling biological treatment.The sewage treatment system for photocatalytic coupling biological treatment.The sewage treatment system for photocatalytic coupling biological treatmentcomprises a pretreatment unit, a photocatalytic unit, an electrochemical biological unit, a post-treatment unit and an intelligent control unit, the pretreatment unit comprises a microwave-ozone coupling reactor and a magnetic adsorption column; the photocatalysis unit comprises a dual-band reaction tower; the electrochemical biological unit comprises a three-dimensional electrode biological membrane assembly and a FeS2 filler layer, the anode of the three-dimensional electrode biological membrane assembly is boron-doped diamond, and the cathode of the three-dimensional electrode biological membrane assembly is a carbon felt of anaerobic ammonium oxidation bacteria. Through multi-stage cooperative treatment, heavy metal ions and organic matters in the sewage are effectively removed, the removal rate of the heavy metal Cr (VI) is greater than 99.9%, the removal rate of the refractory organic matter benzene is greater than 99.9%, and the method has multi-scene applicability and efficient treatment capacity.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a wastewater treatment system and method that couples photocatalysis with biological treatment. Background Technology

[0002] Water pollution is caused by harmful chemicals that reduce or eliminate the usability of water. Heavy metals (such as Cr(VI) and Cd(II)) and persistent organic compounds (such as benzene compounds) in wastewater can poison aquatic life and affect drinking water sources. Furthermore, the decomposition of organic matter in wastewater by microorganisms consumes oxygen in the water, affecting the life of aquatic organisms. After the dissolved oxygen in the water is depleted, the organic matter undergoes anaerobic decomposition, producing foul-smelling gases such as hydrogen sulfide and mercaptans, further deteriorating the water quality.

[0003] Currently, existing wastewater treatment methods mainly employ a step-by-step treatment strategy, but these methods have significant drawbacks in terms of technological synergy, treatment efficiency, and operating costs. For example, the sedimentation method: adding excess FeSO4 (molar ratio 1:8) at pH 8-9 can reduce Cr(VI) to Cr(III) and precipitate it, but it produces 3.5 kg / m³ of sludge containing heavy metals. 3 Based on a daily processing capacity of 2000m³ 3 Calculations show that the annual sludge production reaches 2,555 tons, and the subsequent hazardous waste disposal cost accounts for 42% of the total operating cost (approximately 1.8 million yuan per year). Even more serious is the residual Fe... 2 + It will undergo a Fenton reaction with organic matter in subsequent treatment units, leading to process disruption. Adsorption method: The theoretical adsorption capacity of commercial activated carbon for Cr(VI) is only 35 mg / g (at pH=2). In actual operation, due to competitive adsorption effects, the adsorption efficiency decreases by 63% when the concentration of benzene series compounds is >50 ppm. A case study of a dyeing and printing plant shows that when using zeolite to adsorb Cd(II), an influent concentration of 0.8 ppm requires a 45-minute empty bed contact time to meet the standard, resulting in an increase in the adsorbent replacement frequency to twice a week, increasing annual material costs by 850,000 yuan. Biological treatment: When Cu 2 When the concentration is greater than 2 ppm, the activity of microbial dehydrogenase decreases by 72%, and the COD removal rate drops sharply from 85% to 32%. Monitoring data from a petrochemical wastewater treatment plant shows that when the MLVSS in the aeration tank decreases from 3500 mg / L to 1200 mg / L, an additional 150 kg / d of biological activator is required to maintain system stability, increasing the annual reagent cost by 540,000 yuan.

[0004] Technical problems exist: (1) Poor synergy in pollutant treatment: In the existing stepwise treatment process, there is chemical antagonism between heavy metal precipitants and organic oxidants. For example, when the dosage of FeSO4 exceeds 2 mol / L, it will inhibit the catalytic decomposition efficiency of H2O2. (2) Bottleneck in treatment efficiency: The dynamic adsorption capacity of commercial zeolite for Cr(VI) is only 32-35 mg / g, and the adsorption rate drops sharply by 60% when pH>7. Summary of the Invention

[0005] In view of this, the present invention proposes a wastewater treatment system and method that couples photocatalysis with biological treatment, aiming to solve the problems of poor technical synergy and low treatment efficiency in the current technology.

[0006] On the one hand, the present invention provides a wastewater treatment system with photocatalytic coupled biological treatment, comprising a pretreatment unit, a photocatalytic unit, an electrochemical biological unit, a posttreatment unit and an intelligent control unit connected in sequence; The pretreatment unit includes: a microwave-ozone coupled reactor and a magnetic adsorption column; The photocatalytic unit includes: a dual-band reaction tower; The electrochemical biological unit includes a three-dimensional electrode biofilm assembly and an FeS2 filler layer. The anode of the three-dimensional electrode biofilm assembly is boron-doped diamond, and the cathode is carbon felt of anaerobic ammonia-oxidizing bacteria.

[0007] Preferably, the microwave-ozone coupled reactor is equipped with dual-frequency waveguides and temperature feedback control; the frequencies of the dual-frequency waveguides are 2.45 GHz and 5.8 GHz, respectively, and the temperature range of the temperature feedback control is 65-68℃.

[0008] Preferably, the filler of the magnetic adsorption column is Fe3O4@MIL-101 core-shell material, and the thiol density of the MOF shell of the Fe3O4@MIL-101 core-shell material is ≥5.2mmol / g.

[0009] Preferably, the dual-band reaction tower includes an upper visible light zone and a lower light source zone; The upper visible light region includes an LED lamp group and an Ag-TiO2 / graphene aerogel catalyst, and the lower light source region includes a UVA-infrared synergistic light source and a BiOI / WO3 heterojunction. The peak wavelength of the UVA-infrared synergistic light source is 360-370nm, and the infrared laser power density is 13-17W / cm². 2 .

[0010] Preferably, the post-processing unit includes: a transgenic reed adsorption bed overexpressing the MT gene and a pH-responsive nanofiltration membrane.

[0011] Preferably, the root MT secretion amount of the transgenic reed adsorption bed overexpressing the MT gene is ≥2.3 μg / g·FW.

[0012] Preferably, the intelligent control unit includes a parameter feedback system and a solar-capacitor power supply system.

[0013] Preferably, the parameter feedback system includes a combined XRF heavy metal detector and an FTIR organic matter analysis module, and the detection cycle of the parameter feedback system is ≤15 minutes; The capacitor in the solar-capacitor power supply system is a graphene / carbon nanotube composite capacitor.

[0014] As a preferred option, it also includes: The detection parameters of the parameter feedback system are obtained, including chemical elements and their corresponding element content values ​​obtained based on the XRF heavy metal detector, and organic matter and its corresponding organic matter content values ​​obtained based on the FTIR organic matter analysis module. Based on the element content value and the organic matter content value, determine whether the corresponding element or organic matter is at a preset sensitivity value. When the element content value and / or the organic matter content value is greater than the sensitivity value, obtain a number of element content values ​​and / or organic matter content values ​​after the sensitivity value. Establish a time-sensitivity value curve based on the data obtained multiple times, analyze the time-sensitivity value curve, and determine whether to issue an early warning. When analyzing the time-sensitivity curve, the slope of the sensitivity value relative to the time-sensitivity curve is obtained; When the slope is negative, the element content values ​​and / or organic matter content values ​​that are greater than the sensitivity value are compared with a preset content threshold; when the element content values ​​and / or organic matter content values ​​are greater than or equal to their respective content thresholds, an early warning is issued; when the element content values ​​and / or organic matter content values ​​are less than their respective content thresholds, no early warning is issued. When the slope is positive, the content threshold is adjusted to obtain a corrected content threshold. The content values ​​of the elements and / or organic matter after a certain number of values ​​that are greater than the sensitivity value are compared with the corrected content threshold. When the content values ​​of the elements and / or organic matter are greater than or equal to their respective corrected content thresholds, an early warning is issued; when the content values ​​of the elements and / or organic matter are less than their respective corrected content thresholds, no early warning is issued. When adjusting the content threshold, the adjustment is made according to the magnitude of the slope, and the corrected content threshold satisfies the following relationship: ; ; in, To correct the content threshold, The content threshold, The sensitivity coefficient is 1 ≤ ≤3, For adjustment function, This refers to the time interval from when the elemental content value or organic matter content value exceeded the sensitive value to the present. and Let A be a constant, 0.1 ≤ A ≤ 10, and 0.01 ≤ B ≤ 1. The slope; After the content threshold is adjusted, the corrected content threshold replaces the original content threshold.

[0015] On the other hand, the present invention also provides a method for a wastewater treatment system with photocatalytic coupled biological treatment, comprising the following steps: Wastewater is discharged into the microwave-ozone coupled reactor of the pretreatment unit to break down heavy metal-organic complexes and release free heavy metal ions; It then enters the dual-band reaction tower of the photocatalytic unit, where a reduction reaction takes place in the upper visible light zone of the dual-band reaction tower. After the reduction reaction is completed, it enters the lower light source zone to degrade benzene series compounds in the wastewater. The wastewater then enters the three-dimensional electrode biofilm assembly of the electrochemical biological unit, where organic matter in the wastewater is reduced through an open loop, and heavy metals are settled through the FeS2 packing layer. The wastewater then enters the transgenic reed adsorption bed overexpressing the MT gene in the post-treatment unit for chelation reaction. The pH-responsive nanofiltration membrane can retain dissolved organic matter in the wastewater. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metals in wastewater in real time to ensure that the heavy metal concentration meets the standards, and the FTIR organic matter analysis module identifies characteristic organic matter to ensure that the organic matter concentration meets the standards.

[0016] Preferably, in the microwave-ozone coupled reactor, the ozone concentration is 18-22 mg / L, the microwave power is 2-3 kW, and the treatment time is 20-30 min; The hydraulic residence time in the upper visible light region is 28-32 minutes, and the hydraulic residence time in the lower light source region is 18-22 minutes.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a wastewater treatment system with photocatalytic coupled biological treatment, comprising a pretreatment unit, a photocatalytic unit, an electrochemical biological unit, a posttreatment unit, and an intelligent control unit connected in sequence; the pretreatment unit includes a microwave-ozone coupled reactor and a magnetic adsorption column; the photocatalytic unit includes a dual-band reaction tower; the electrochemical biological unit includes a three-dimensional electrode biofilm assembly and an FeS2 packing layer, wherein the anode of the three-dimensional electrode biofilm assembly is boron-doped diamond, and the cathode is a carbon felt of anaerobic ammonia-oxidizing bacteria.

[0018] The pretreatment unit of this invention uses a microwave-ozone coupled reactor and a magnetic adsorption column. The microwave cavitation effect in the microwave-ozone coupled reactor enables ozone microbubbles to break down heavy metal-organic complexes (such as Cu-EDTA), improving the release efficiency of free heavy metals. Simultaneously, ozone oxidizes and decomposes large organic molecules (such as lignin), creating favorable conditions for subsequent biological treatment in the electrochemical-biological unit. Furthermore, the magnetic adsorption column exhibits selective adsorption, selectively adsorbing ions such as As(III) and Hg(II), reducing the heavy metal ion load on the photocatalytic unit. The photocatalytic unit includes a dual-band reaction tower capable of reducing high-valence heavy metals (Cr(VI)→Cr(III)) and degrading recalcitrant organic compounds (such as benzene compounds), avoiding the inhibition of biological activity by intermediate products in the subsequent electrochemical-biological unit. The boron-doped diamond anode in the electrochemical-biological unit has a high oxygen evolution potential, generating strong oxidizing free radicals and improving the ring-opening efficiency of organic degradation. When anaerobic ammonia-oxidizing bacteria are used as a carbon felt as a cathode, the carbon felt carrier loads the bacterial community to achieve NH4+. + Directly converted to N2, simultaneously degrading photocatalytic residual organic matter; the FeS2 filler layer can release S in situ. 2- These substances react with heavy metal ions in wastewater to form stable sulfide precipitates (such as CuS). This invention effectively removes heavy metal ions and organic matter from wastewater through multi-stage synergistic treatment. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] This invention provides a wastewater treatment system with photocatalytic coupled biological treatment, comprising a pretreatment unit, a photocatalytic unit, an electrochemical biological unit, a posttreatment unit, and an intelligent control unit connected in sequence. The pretreatment unit includes: a microwave-ozone coupled reactor and a magnetic adsorption column; The photocatalytic unit includes: a dual-band reaction tower; The electrochemical biological unit includes a three-dimensional electrode biofilm assembly and an FeS2 filler layer. The anode of the three-dimensional electrode biofilm assembly is boron-doped diamond, and the cathode is carbon felt of anaerobic ammonia-oxidizing bacteria.

[0021] In some embodiments of the present invention, the microwave-ozone coupling reactor is equipped with a dual-frequency waveguide and temperature feedback control; the frequencies of the dual-frequency waveguide are 2.45 GHz and 5.8 GHz, respectively. The 2.45 GHz band can promote the decomposition of ozone into •OH radicals; the 5.8 GHz band can excite the molecular vibrations of polar organic compounds (such as phenols), directly breaking chemical bonds through non-thermal effects. The temperature range of the temperature feedback control is 65-68°C, which can synergistically work with the frequencies of the dual-frequency waveguide to promote the efficient decomposition of ozone into •OH radicals.

[0022] In some embodiments of the present invention, the method for preparing the FeS2 filler layer includes the following steps: FeSO4·7H2O, thiourea, hexadecyltrimethylammonium bromide, and water were mixed and subjected to a hydrothermal reaction to obtain the FeS2 filler layer.

[0023] In some embodiments of the present invention, the mass ratio of FeSO4·7H2O, thiourea, and hexadecyltrimethylammonium bromide is 4.5:3.8:0.5.

[0024] In some embodiments of the present invention, the temperature of the hydrothermal reaction is 170-180°C, and the time of the hydrothermal reaction is 10-14 hours.

[0025] In some embodiments of the present invention, the packing material of the magnetic adsorption column is Fe3O4@MIL-101 core-shell material, and the thiol density of the MOF shell layer of the Fe3O4@MIL-101 core-shell material is ≥5.2 mmol / g. Fe3O4@MIL-101 can adsorb Hg from wastewater. 2+ Cd 2+ Plasma.

[0026] In some embodiments of the present invention, the preparation method of the Fe3O4@MIL-101 core-shell material includes the following steps: Under a protective atmosphere, FeCl3, FeSO4 and water were mixed and stirred. NH3·H2O was added to the mixture and stirring was continued. After obtaining a mixed solution, the mixed solution was separated to obtain Fe3O4 precipitate. After precipitating and purifying Fe3O4, washing was performed to obtain Fe3O4 nanoparticles. Fe3O4 nanoparticles were dissolved in N,N-dimethylformamide, and 2-mercaptoterephthalic acid was added and stirred. Then, Cr(NO3)3·9H2O and hydrofluoric acid were added, and a solvothermal reaction was carried out to obtain the Fe3O4@MIL-101 core-shell material.

[0027] In some embodiments of the present invention, the protective atmosphere is nitrogen, the mass-to-volume ratio of FeCl3, FeSO4 and NH3·H2O is 5.4g:2.7g:50mL, the mass concentration of NH3·H2O is 20%-30%, and the mass-to-volume ratio of Fe3O4 nanoparticles, 2-mercaptoterephthalic acid, Cr(NO3)3·9H2O and hydrofluoric acid is 1g:2g:1.8g:0.2mL.

[0028] In some embodiments of the present invention, the temperature of the solvothermal reaction is 140-160°C, and the time of the solvothermal reaction is 24 hours.

[0029] In some embodiments of the present invention, the dual-band reaction tower includes an upper visible light zone and a lower light source zone; The upper visible light region includes an LED light group and an Ag-TiO2 / graphene aerogel catalyst. The LED light group has a wavelength of 420 nm, which can excite the Ag-TiO2 / graphene aerogel, enabling photogenerated electrons to directionally reduce Cr(VI) to Cr(III). Simultaneously, the graphene aerogel has a large specific surface area, which can effectively adsorb free heavy metal ions (such as Pb). 2+ Cd 2+ ); The lower-level light source region includes: a UVA-infrared synergistic light source and a BiOI / WO3 heterojunction; the peak wavelength of the UVA-infrared synergistic light source is 360-370nm, and the infrared laser power density is 13-17W / cm². 2 A 360-370nm UVA infrared synergistic light source can excite the BiOI / WO3 heterojunction to generate h. + With •O2 - It degrades benzene compounds (such as toluene) and perfluorinated compounds (such as PFOA).

[0030] In some embodiments of the present invention, the post-processing unit includes: a transgenic reed adsorption bed overexpressing the MT gene and a pH-responsive nanofiltration membrane. The reed roots overexpressing the metallothionein (MT) gene secrete MT protein, which adsorbs residual heavy metals (such as Cd) through strong chelation with thiol groups (-SH). 2+ Pb 2+ pH-responsive nanofiltration membranes can retain dissolved organic matter (such as phenol and dye molecules).

[0031] In some embodiments of the present invention, the root MT secretion amount of the transgenic reed adsorption bed overexpressing the MT gene is ≥2.3 μg / g·FW.

[0032] In some embodiments of the present invention, the intelligent control unit includes a parameter feedback system and a solar-capacitor power supply system.

[0033] In some embodiments of the present invention, the parameter feedback system includes a combined XRF heavy metal detector and an FTIR organic matter analysis module, and the detection cycle of the parameter feedback system is ≤15 minutes; The capacitor in the solar-capacitor power supply system is a graphene / carbon nanotube composite capacitor.

[0034] In some embodiments of the present invention, it further includes: The detection parameters of the parameter feedback system are obtained, including chemical elements and their corresponding content values ​​obtained based on the XRF heavy metal detector, and organic matter and its corresponding content values ​​obtained based on the FTIR organic matter analysis module. Based on the element content value and the organic matter content value, determine whether the corresponding element or organic matter is at a pre-set sensitivity value. When the element content value and / or the organic matter content value is greater than the sensitivity value, obtain a number of element content values ​​and / or organic matter content values ​​after the sensitivity value is greater than the sensitivity value. Based on the data obtained multiple times, establish a time-sensitivity value curve, analyze the time-sensitivity value curve, and determine whether to issue an early warning. When analyzing the time-sensitivity curve, obtain the slope of the sensitivity value relative to the time-sensitivity curve; When the slope is negative, the element content values ​​and / or organic matter content values ​​after a certain number of values ​​that are greater than the sensitivity value are compared with the preset content thresholds; when the element content values ​​and / or organic matter content values ​​are greater than or equal to their respective content thresholds, an alert is issued; when the element content values ​​and / or organic matter content values ​​are less than their respective content thresholds, no alert is issued. When the slope is positive, the content threshold is adjusted to obtain a corrected content threshold. The content values ​​of elements and / or organic matter that are several times higher than the sensitivity value are compared with the corrected content threshold. When the content values ​​of elements and / or organic matter are greater than or equal to their respective corrected content thresholds, an alert is issued; when the content values ​​of elements and / or organic matter are less than their respective corrected content thresholds, no alert is issued. When adjusting the content threshold, the adjustment is based on the magnitude of the slope, and the corrected content threshold satisfies the following relationship: ; ; in, To correct the content threshold, The content threshold, The sensitivity coefficient is 1 ≤ ≤3, For adjustment function, This refers to the time interval from when the elemental content value or organic matter content value exceeded the sensitive value to the present. and Let A be a constant, 0.1 ≤ A ≤ 10, and 0.01 ≤ B ≤ 1. The slope; After the content threshold is adjusted, the corrected content threshold replaces the original content threshold.

[0035] On the other hand, this embodiment also provides a method for a wastewater treatment system with photocatalytic coupled biological treatment, comprising the following steps: Wastewater is discharged into the microwave-ozone coupled reactor of the pretreatment unit to break down heavy metal-organic complexes and release free heavy metal ions; It then enters the dual-band reaction tower of the photocatalytic unit, where a reduction reaction takes place in the upper visible light zone of the dual-band reaction tower. After the reduction reaction is completed, it enters the lower light source zone to degrade benzene series compounds in the wastewater. The wastewater then enters the three-dimensional electrode biofilm assembly of the electrochemical biological unit, where organic matter in the wastewater is reduced through an open loop, and heavy metals are settled through the FeS2 packing layer. The wastewater then enters the transgenic reed adsorption bed overexpressing the MT gene in the post-treatment unit for chelation reaction. The pH-responsive nanofiltration membrane can retain dissolved organic matter in the wastewater. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metals in wastewater in real time to ensure that the heavy metal concentration meets the standards, and the FTIR organic matter analysis module identifies characteristic organic matter to ensure that the organic matter concentration meets the standards.

[0036] In some embodiments of the present invention, the ozone concentration in the microwave-ozone coupled reactor is 18-22 mg / L, the microwave power is 2-3 kW, and the treatment time is 20-30 min. The hydraulic residence time in the upper visible light region is 28-32 minutes, and the hydraulic residence time in the lower light source region is 18-22 minutes.

[0037] In some embodiments of the present invention, the bottom outlet of the microwave-ozone coupling reactor is connected to the inlet at the top of the magnetic adsorption column. The temperature feedback control is located inside the microwave-ozone coupling reactor for detecting real-time temperature. The effluent from the magnetic adsorption column flows by gravity into the upper visible light zone of the dual-band reaction tower, and is then pumped into the lower light source zone of the dual-band reaction tower by a centrifugal pump. The effluent from the lower light source zone is controlled by an electromagnetic flow meter to enter the three-dimensional electrode biofilm assembly. The effluent from the three-dimensional electrode biofilm assembly is pumped into the FeS2 packing layer. The supernatant from the upper layer of the FeS2 packing layer is pumped into the supernatant of the packing layer and into the transgenic reed adsorption bed overexpressing the MT gene. The effluent is pumped into a pH-responsive nanofiltration membrane.

[0038] In some embodiments of the present invention, the XRF heavy metal detector is installed at the outlet of the photocatalytic unit, and the FTIR spectrometer is located at the inlet of the electrochemical unit.

[0039] In the following embodiments, the method for preparing the FeS2 packing layer includes the following steps: 4.5g FeSO4·7H2O, 3.8g thiourea, and 0.5g hexadecyltrimethylammonium bromide were dissolved in water and subjected to a hydrothermal reaction at 180℃ for 12h to obtain the FeS2 filler layer.

[0040] The preparation method of the Fe3O4@MIL-101 core-shell material in the following embodiments includes the following steps: Under a nitrogen atmosphere, 5.4 g FeCl3, 2.7 g FeSO4 and water were mixed and stirred. NH3·H2O was added to the mixture until the pH of the mixture was 10. Stirring was continued for 1 h to obtain a mixed solution. The mixed solution was then separated to obtain Fe3O4 precipitate. After precipitating and purifying Fe3O4, washing was performed to obtain Fe3O4 nanoparticles. 1g of Fe3O4 nanoparticles were dissolved in N,N-dimethylformamide, and 1.8g of 2-mercaptoterephthalic acid was added and stirred. Then, 2g of Cr(NO3)3·9H2O and 0.2mL of hydrofluoric acid were added, and the mixture was hydrothermally reacted at 150℃ for 24h to obtain the Fe3O4@MIL-101 core-shell material.

[0041] Example 1 The wastewater from electroplating plants mainly contains Cr(VI) and Cu. 2+ And electroplating additives, water quality parameters are as follows: Cr(VI) = 28.5 mg / L, Cu 2+ =22.3mg / L, COD=520mg / L, NH4 + -N=35.6mg / L, pH=2.4.

[0042] Wastewater was discharged into the microwave-ozone coupled reactor of the pretreatment unit. Dual-frequency microwaves (2.45GHz / 5.8GHz, power 2.8kW), ozone concentration 20mg / L, treatment time 25min, and temperature feedback control maintained at 65℃ were used to break down Cu-EDTA complexes and release free heavy metal ions. A magnetic adsorption column (Fe3O4@MIL-101 core-shell material, thiol density 5.8mmol / g), packed to a height of 1.2m, with a magnetic field strength of 0.35T, selectively adsorbed As(III) and Hg. 2+ .

[0043] It then enters the dual-band reaction tower of the photocatalytic unit, where a reduction reaction takes place in the upper visible light zone (420nm LED, Ag-TiO2 / graphene catalyst (Ag 1.8wt%), hydraulic residence time 30min, DO=0.3mg / L). After the reduction reaction is completed, it enters the lower light source zone (365nm UVA, hydraulic residence time 20min) to degrade benzene compounds in the wastewater. Subsequently, the three-dimensional electrode biofilm assembly of the electrochemical biological unit (boron-doped diamond anode with a current density of 35 mA / cm²) was introduced. 2 Anaerobic ammonia-oxidizing bacteria loaded on carbon felt cathode (bacterial concentration 1×10⁻⁶) 6 (CFU / g), voltage 3.2V), open-ring deionization of benzoquinone in wastewater, through the FeS2 packing layer, generates CuS precipitate; The transgenic reeds overexpressing the MT gene were then introduced into the post-treatment unit to perform a chelation reaction in an adsorption bed (MT secretion rate 2.8 μg / g·FW, hydraulic retention time 24 h). The pH-responsive nanofiltration membrane retained citric acid complexes with a molecular weight cutoff of 200 Da at pH 5.2. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metal Cr(VI) in wastewater in real time until Cr(VI) < 1 ppm; the FTIR organic matter analysis module identifies C=O bonds to ensure that the organic matter concentration meets the standard.

[0044] Example 2 The wastewater from the printing and dyeing factory contains reactive dyes and benzene-based solvents. The water quality parameters are as follows: color = 850 times (dilution ratio method), benzene = 95 mg / L, Cr(VI) = 10.2 mg / L, COD = 1480 mg / L, pH = 8.5.

[0045] Wastewater is discharged into the microwave-ozone coupled reactor of the pretreatment unit, using dual-frequency microwave (2.45GHz / 5.8GHz, power 3kW), ozone concentration 22mg / L, treatment time 28min, and temperature feedback control to maintain 65℃, to break down anthraquinone dye molecules; It then enters the dual-band reaction tower of the photocatalytic unit, where the reduction reaction takes place in the upper visible light zone (420nm LED, Ag-TiO2 / graphene catalyst (Ag 1.8wt%), hydraulic residence time 30min, DO=0.3mg / L). After the reduction reaction is completed, it enters the lower light source zone (365nm UVA, hydraulic residence time 20min) to accelerate the degradation of benzene compounds. Subsequently, the three-dimensional electrode biofilm assembly of the electrochemical biological unit (boron-doped diamond anode with a current density of 35 mA / cm²) was introduced. 2 Anaerobic ammonia-oxidizing bacteria loaded on carbon felt cathode (bacterial concentration 1×10⁻⁶) 6 (CFU / g), voltage 3.2V), open-ring deionization of benzoquinone in wastewater, through the FeS2 packing layer, generates PbS precipitate; The transgenic reeds overexpressing the MT gene were then introduced into the post-treatment unit to perform a chelation reaction in an adsorption bed (MT secretion rate 3.0 μg / g·FW, hydraulic retention time 24 h). The pH-responsive nanofiltration membrane retained dye intermediates with a molecular weight of 500 Da at pH 5.0. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metal Cr(VI) in wastewater in real time until Cr(VI) < 1 ppm; the FTIR organic matter analysis module identifies the characteristic peak of benzene ring to ensure that the organic matter concentration meets the standard.

[0046] Example 3 Mineral wastewater: containing As(III) and Fe 3+ And sulfate, the water quality parameters are as follows: As(III) = 40.5 mg / L, Fe 3+ =125mg / L, SO4 2- =4500mg / L, pH=1.7.

[0047] Wastewater is discharged into the microwave-ozone coupled reactor of the pretreatment unit, using dual-frequency microwaves (2.45GHz / 5.8GHz, power 2.5kW), ozone concentration of 18mg / L, treatment time of 22min, and temperature feedback control to maintain 65℃, targeting the breaking of As-S bonds.

[0048] It then enters the dual-band reaction tower of the photocatalytic unit, where Fe2+ is reacted in the upper visible light region of the dual-band reaction tower. 3+ →Fe 2+ The reduction reaction (420nm LED, Ag-TiO2 / graphene catalyst (Ag 1.8wt%), hydraulic residence time 30min, DO=0.3mg / L) was initiated. After the reduction reaction was completed, the system moved to the lower light source zone (365nm UVA, hydraulic residence time 18min) to degrade thiosulfate (S2O3). 2- →SO42- ); Subsequently, the three-dimensional electrode biofilm assembly of the electrochemical biological unit (boron-doped diamond anode with a current density of 35 mA / cm²) was introduced. 2 Anaerobic ammonia-oxidizing bacteria loaded on carbon felt cathode (bacterial concentration 1×10⁻⁶) 6 (CFU / g), voltage 3.2V), open-ring deionization of benzoquinone in wastewater, through FeS2 packing layer, generates As2S3 precipitate; Subsequently, the reeds, overexpressing the MT gene, were placed in the post-processing unit and placed in a transgenic reed adsorption bed (MT secretion rate 2.5 μg / g·FW, hydraulic retention time 24 h) to enrich As. 3+ pH-responsive nanofiltration membranes retain As2S3 colloids (particle size 20-60nm) at pH 2. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metal As(III) in wastewater in real time until it meets the standard.

[0049] Example 4 The industrial park's mixed wastewater contains various heavy metals and complex organic matter. The water quality parameters are as follows: Cr(VI) = 18.6 mg / L, Cd... 2+ =12.3mg / L, benzene=78mg / L, COD=980mg / L, NH4 + -N=50.5mg / L, pH=3.0.

[0050] Wastewater was discharged into the microwave-ozone coupled reactor of the pretreatment unit. Dual-frequency microwaves (2.45GHz / 5.8GHz, 3kW power) were used, with an ozone concentration of 22mg / L, a treatment time of 30min, and temperature feedback control maintained at 68℃ to break down the Cd-EDTA complex. A magnetic adsorption column was used: Fe3O4@MIL-101 core-shell material (thiol density 5.8mmol / g), packing height 1.5m, magnetic field strength 0.35T, selectively adsorbing Cd. 2+ .

[0051] It then enters the dual-band reaction tower of the photocatalytic unit, where the reduction reaction Cr(VI)→Cr(III) takes place in the upper visible light zone (420nm LED, Ag-TiO2 / graphene catalyst (Ag 1.8wt%), hydraulic residence time 32min, DO=0.3mg / L). After the reduction reaction is completed, it enters the lower light source zone (365nm UVA, hydraulic residence time 22min) to degrade benzene series compounds in wastewater. Subsequently, the three-dimensional electrode biofilm assembly of the electrochemical biological unit (boron-doped diamond anode with a current density of 40 mA / cm²) was introduced. 2 Anaerobic ammonia-oxidizing bacteria were loaded onto the carbon felt cathode (bacterial concentration 1.2 × 10⁻⁶). 6(CFU / g), voltage 3.2V), removal of NH4 + -N passes through the FeS2 packing layer to generate CdS precipitate; The reeds then entered the post-processing unit and were placed in a transgenic reed adsorption bed overexpressing the MT gene (MT secretion rate 2.3 μg / g·FW, hydraulic retention time 24 h) to enrich Cd. 2+ pH-responsive nanofiltration membranes retain organic acid complexes with a molecular weight of 200 Da at a pH of 5.5; The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metal Cr(VI) in wastewater in real time until Cr(VI) < 1 ppm; the FTIR organic matter analysis module identifies the characteristic peak of benzene ring to ensure that the organic matter concentration meets the standard.

[0052] Test case The influent and effluent water quality of Example 1 were tested, and the results are shown in Table 1.

[0053] Table 1. Water quality comparison results of Example 1

[0054] The influent and effluent water quality of Example 2 were tested, and the results are shown in Table 2.

[0055] Table 2. Water quality comparison results of Example 2

[0056] The influent and effluent water quality of Example 3 were tested, and the results are shown in Table 3.

[0057] Table 3. Water quality comparison results of Example 3

[0058] The influent and effluent water quality of Example 4 were tested, and the results are shown in Table 4.

[0059] Table 4. Water quality comparison results of Example 4

[0060] As shown in Tables 1-4, the wastewater treatment system with photocatalytic coupled biological treatment provided by this invention has applicability to multiple scenarios and high treatment efficiency. The removal rate of heavy metal Cr(VI) is >99.9%, and the removal rate of recalcitrant organic compound benzene is >99.9%.

[0061] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A wastewater treatment system with photocatalysis coupled with biological treatment, characterized in that, It includes a pretreatment unit, a photocatalysis unit, an electrochemical-biological unit, a post-treatment unit, and an intelligent control unit connected in sequence; The pretreatment unit includes: a microwave-ozone coupled reactor and a magnetic adsorption column; The photocatalytic unit includes: a dual-band reaction tower; The electrochemical biological unit includes a three-dimensional electrode biofilm assembly and an FeS2 filler layer. The anode of the three-dimensional electrode biofilm assembly is boron-doped diamond, and the cathode is carbon felt of anaerobic ammonia-oxidizing bacteria.

2. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 1, characterized in that, The microwave-ozone coupled reactor is equipped with dual-frequency waveguides and temperature feedback control; the frequencies of the dual-frequency waveguides are 2.45 GHz and 5.8 GHz, respectively, and the temperature range of the temperature feedback control is 65-68℃.

3. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 1, characterized in that, The magnetic adsorption column is filled with Fe3O4@MIL-101 core-shell material, and the thiol density of the MOF shell of the Fe3O4@MIL-101 core-shell material is ≥5.2mmol / g.

4. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 1, characterized in that, The dual-band reaction tower includes an upper visible light zone and a lower light source zone; The upper visible light region includes an LED lamp group and an Ag-TiO2 / graphene aerogel catalyst, and the lower light source region includes a UVA-infrared synergistic light source and a BiOI / WO3 heterojunction. The peak wavelength of the UVA-infrared synergistic light source is 360-370nm, and the infrared laser power density is 13-17W / cm². 2 .

5. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 1, characterized in that, The post-processing unit includes: a transgenic reed adsorption bed overexpressing the MT gene and a pH-responsive nanofiltration membrane.

6. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 5, characterized in that, The transgenic reed adsorption bed overexpressing the MT gene has a root MT secretion amount ≥2.3 μg / g·FW.

7. The wastewater treatment system with photocatalytic coupled biological treatment according to claim 1, characterized in that, The intelligent control unit includes a parameter feedback system and a solar-capacitor power supply system.

8. A wastewater treatment system with photocatalytic coupled biological treatment according to claim 7, characterized in that, The parameter feedback system includes a combined XRF heavy metal detector and an FTIR organic matter analysis module, and the detection cycle of the parameter feedback system is ≤15 minutes. The capacitor in the solar-capacitor power supply system is a graphene / carbon nanotube composite capacitor.

9. A wastewater treatment system with photocatalytic coupled biological treatment according to claim 8, characterized in that, Also includes: The detection parameters of the parameter feedback system are obtained, including chemical elements and their corresponding element content values ​​obtained based on the XRF heavy metal detector, and organic matter and its corresponding organic matter content values ​​obtained based on the FTIR organic matter analysis module. Based on the element content value and the organic matter content value, determine whether the corresponding element or organic matter is at a preset sensitivity value. When the element content value and / or the organic matter content value is greater than the sensitivity value, obtain a number of element content values ​​and / or organic matter content values ​​after the sensitivity value. Establish a time-sensitivity value curve based on the data obtained multiple times, analyze the time-sensitivity value curve, and determine whether to issue an early warning. When analyzing the time-sensitivity curve, the slope of the sensitivity value relative to the time-sensitivity curve is obtained; When the slope is negative, the element content values ​​and / or organic matter content values ​​that are greater than the sensitivity value are compared with a preset content threshold; when the element content values ​​and / or organic matter content values ​​are greater than or equal to their respective content thresholds, an early warning is issued; when the element content values ​​and / or organic matter content values ​​are less than their respective content thresholds, no early warning is issued. When the slope is positive, the content threshold is adjusted to obtain a corrected content threshold. The content values ​​of the elements and / or organic matter after a certain number of values ​​that are greater than the sensitivity value are compared with the corrected content threshold. When the content values ​​of the elements and / or organic matter are greater than or equal to their respective corrected content thresholds, an early warning is issued; when the content values ​​of the elements and / or organic matter are less than their respective corrected content thresholds, no early warning is issued. When adjusting the content threshold, the adjustment is made according to the magnitude of the slope, and the corrected content threshold satisfies the following relationship: ； ； in, To correct the content threshold, The content threshold, Sensitivity coefficient , For adjustment function, This refers to the time interval from when the elemental content value or organic matter content value exceeded the sensitive value to the present. and Let A be a constant, 0.1 ≤ A ≤ 10, and 0.01 ≤ B ≤ 1. The slope; After the content threshold is adjusted, the corrected content threshold replaces the original content threshold.

10. A method for a wastewater treatment system with photocatalytic coupled biological treatment as described in any one of claims 1-9, characterized in that, Includes the following steps: Wastewater is discharged into the microwave-ozone coupled reactor of the pretreatment unit to break down heavy metal-organic complexes and release free heavy metal ions; It then enters the dual-band reaction tower of the photocatalytic unit, where a reduction reaction takes place in the upper visible light zone of the dual-band reaction tower. After the reduction reaction is completed, it enters the lower light source zone to degrade benzene series compounds in the wastewater. The wastewater then enters the three-dimensional electrode biofilm assembly of the electrochemical biological unit, where organic matter in the wastewater is reduced through an open loop, and heavy metals are settled through the FeS2 packing layer. The wastewater then enters the transgenic reed adsorption bed overexpressing the MT gene in the post-treatment unit for chelation reaction. The pH-responsive nanofiltration membrane can retain dissolved organic matter in the wastewater. The XRF heavy metal detector in the intelligent control unit monitors the concentration of heavy metals in wastewater in real time to ensure that the heavy metal concentration meets the standards, and the FTIR organic matter analysis module identifies characteristic organic matter to ensure that the organic matter concentration meets the standards. In the microwave-ozone coupled reactor, the ozone concentration is 18-22 mg / L, the microwave power is 2-3 kW, and the treatment time is 20-30 min. The hydraulic residence time in the upper visible light region is 28-32 minutes, and the hydraulic residence time in the lower light source region is 18-22 minutes.

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