Photoelectrocatalytic advanced oxidation-suspended carrier biofilm reactor coupling system and wastewater treatment method

Abstract

This invention relates to the field of wastewater treatment technology, specifically disclosing a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor (MBBR) coupled system and wastewater treatment method. The coupled system includes a photoelectrocatalytic advanced oxidation system and a suspended packing biofilm reactor; the photoelectrocatalytic advanced oxidation system includes a photoanode, a photocathode, an electrolytic cell, a power supply, and a light source; the suspended packing biofilm reactor includes a biofilm tank, an aeration device, activated sludge, a porous biofilm carrier, and coconut shell powder. This invention, by coordinating the operation of the coupled system, employs a photoelectrocatalytic advanced oxidation system preceding a MBBR, and leverages the advantages of coconut shell powder in adsorption, decolorization, and promoting microbial growth and metabolism. This not only improves the treatment efficiency of pollutants in water but also shortens the photoelectrocatalytic advanced oxidation time, achieving rational energy utilization. The coupled system also features environmental friendliness, simple operation, and applicability to various water bodies.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system and wastewater treatment method. Background Technology

[0002] Industrial wastewater is characterized by its complex composition, recalcitrant nature, and large fluctuations in quality and quantity. It contains various organic and inorganic pollutants. For example, dyeing and printing wastewater contains large amounts of dyes and auxiliaries (such as sodium sulfide and sodium hydrosulfite). These organic substances have complex compositions and diverse structures, and some are even biotoxic, making them difficult to remove completely using a single treatment method. Electroplating wastewater is rich in heavy metal ions, such as chromium, nickel, cadmium, and copper. These heavy metals are non-biodegradable, persist in the environment for a long time, and easily accumulate in organisms, posing serious threats to ecosystems and human health. Different heavy metals require different treatment processes for effective removal, increasing the complexity of the treatment process.

[0003] Currently, common methods for treating industrial wastewater include physical, chemical, biological, and combined methods. Physical methods have limited catalyst cycles, while traditional biochemical methods suffer from drawbacks such as large land area requirements, long treatment cycles, and poor treatment efficiency. Photoelectrocatalytic advanced oxidation wastewater treatment technology, under the combined action of light and an applied electric field, excites photoelectrocatalytic materials to generate a large number of electrons and holes. These electrons and holes separate and move directionally, accumulating at the anode and cathode to generate a large number of active free radicals. These highly oxidizing free radicals react with pollutants in the water, mineralizing them into carbon dioxide, water, and inorganic salts, thereby achieving water purification. Furthermore, these active free radicals can purify different types of water and enhance the biodegradability of the treated water, thus reducing the difficulty of advanced treatment. Suspended packed-layer biofilm reactors (MBBRs) are wastewater treatment devices that combine traditional activated sludge and biofilm processes. MBBRs use suspended packing as a carrier for biofilm attachment, utilizing microorganisms to consume nutrients in the water to purify the water. Compared to other biofilm treatment processes, MBBR has advantages in denitrification, resistance to shock loads, and floor space, but it is less effective in treating wastewater with high biological toxicity or poor biodegradability.

[0004] Due to the complex composition of industrial wastewater, a single treatment process often cannot meet the requirements for discharge compliance, and a combination of multiple treatment processes is usually necessary. However, how to rationally select and optimize these combined processes to achieve the best treatment effect through synergistic cooperation is a challenge in industrial wastewater treatment. Therefore, there is an urgent need to develop a coupled wastewater treatment system to improve the limitations of existing technologies in the deep treatment of complex water bodies. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a photocatalytic advanced oxidation-suspended packing biofilm reactor coupling system and wastewater treatment method. By coupling photocatalytic oxidation technology, electrocatalytic reaction technology, and biofilm reactor, the system leverages the synergistic effect of each component, improving the efficiency of deep treatment of complex water bodies. It features simple operation, stable long-term operation, mild reaction conditions, small footprint, and significant wastewater purification efficiency.

[0006] To solve the above-mentioned technical problems, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a coupled system of photoelectrocatalytic advanced oxidation and suspended packing biofilm reactor, comprising: a photoelectrocatalytic advanced oxidation system and a suspended packing biofilm reactor;

[0008] The photoelectrocatalytic advanced oxidation system includes a photoanode, a photocathode, an electrolytic cell, a power source, and a light source;

[0009] The photoanode and the photocathode are located in the electrolytic cell, and the photoanode and the photocathode are respectively connected to the power source through wires; the light source is located outside the electrolytic cell and is used to irradiate the electrolytic cell with light.

[0010] The suspended packing biofilm reactor includes a biofilm tank, an aeration device, activated sludge, a porous biofilm carrier, and coconut shell powder.

[0011] The aeration device is located below the biofilm tank and is used to create an aerobic environment; the activated sludge, porous biofilm carrier and coconut shell powder are located in the biofilm tank;

[0012] The inlet of the biofilm tank is connected to the outlet of the electrolysis tank, and the outlet of the biofilm tank is connected to the inlet of the electrolysis tank, for recirculation and multiple cycles of treatment.

[0013] Compared to existing technologies, the electrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system (hereinafter referred to as the coupled system) provided by this invention offers significant advantages in wastewater treatment. The electrocatalytic advanced oxidation system exhibits high wastewater treatment efficiency but suffers from high energy consumption and limited catalyst cycles, making it more suitable for short-term, frequent operation. In contrast, the MBBR (Mixed Biofilm Reactor) system boasts long-term operational stability and strong resistance to shock loads. This invention, by coupling the electrocatalytic advanced oxidation system with the MBBR, fully leverages the advantages of both systems. It not only enhances the treatment capacity of photocatalysis for complex water bodies but also strengthens the deep treatment efficiency of the MBBR for industrial wastewater. Furthermore, the coupled system improves treatment efficiency while also ensuring rational energy utilization. It reduces water toxicity while improving biodegradability. The two wastewater treatment systems complement each other, meeting the needs for deep treatment of industrial wastewater and possessing high market application value.

[0014] This invention, through a coordinated operation of a coupled system, employs a photoelectrocatalytic advanced oxidation system preceding a molecular bioreactor (MBBR), leveraging the advantages of coconut shell powder in adsorption, decolorization, and promotion of microbial growth and metabolism. This not only enhances the treatment efficiency of pollutants in water but also shortens the photoelectrocatalytic advanced oxidation time, achieving rational energy utilization. The coupled system is also environmentally friendly, simple to operate, and suitable for various water bodies. By connecting the effluent of the biofilm tank to the influent of the electrolysis tank, this invention enables repeated treatment of stubborn substances in complex water bodies.

[0015] Through extensive experiments, this invention has discovered that the microporous structure of coconut shell powder has the effect of adsorbing and fixing nutrient sources. When combined with porous biofilm carriers, it promotes the growth and metabolism of microorganisms, accelerates the growth and film formation of microorganisms on activated sludge and porous biofilm carriers, and significantly improves the activity of microorganisms. At the same time, coconut shell powder has the effect of adsorbing and decolorizing metal ions and toxic pollutants, increasing the purification and cleaning efficiency of pollutants.

[0016] The advanced features of this invention are long-term stable operation, mild reaction conditions, green and low carbon emissions, and strong water treatment effect. It can overcome the defects of high energy consumption and limited catalyst cycle of advanced oxidation technology, and solve the problems of large land area and long treatment cycle of biotechnology. By coupling the photoelectrocatalytic advanced oxidation system with MBBR and the synergistic effect of its components, materials and biofilm structure, it achieves deep treatment of wastewater.

[0017] Preferably, the photoanode includes an anode substrate and a photoanode material supported on the anode substrate;

[0018] The photoelectric anode material includes a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer.

[0019] The photoanode material provided by this invention uses a nano-WSe2 and Bi2O2Fe2O4 semiconductor composite material as the photocatalytic material for the photoanode, utilizing photocatalytic activity to remove pollutants from wastewater. The photocatalytic material WSe2 has a narrow band gap (around 1.65 eV), exhibiting good light absorption and photoelectric storage capabilities, and demonstrates excellent catalytic degradation effects on pollutants. Through doping modification, it can acquire n-type or p-type semiconductor characteristics, sensitizing other semiconductors with wider band gaps to form sensitized nanocomposite materials, reducing the band gap width, improving photoelectric conversion efficiency, thereby generating excellent photocatalytic activity, increasing visible light utilization, increasing the generation of photogenerated electrons, improving the separation and transport rate of photogenerated electrons and photoelectric conversion efficiency, and enhancing wastewater treatment effects. Bismuth metal semiconductors have low toxicity, high conductivity, and an adjustable band gap, possessing excellent photocatalytic activity and photoelectric conversion efficiency. [Bi2O2] 2+ Layer and salt anion [Fe2O4] 2- In the layered structure of the Aurvillius photocatalyst Bi₂O₂Fe₂O₄, [Bi₂O₂] 2+ Layer and anion [Fe2O4] 2- The vertically alternating layers structure is more conducive to promoting the separation of photogenerated electrons and holes, thereby improving the catalytic oxidation reaction activity of the electrode. This invention uses a novel composite of Bi₂O₂Fe₂O₄ and WSe₂ to form a sensitized nanocomposite, which can improve their respective solar photoresponse capabilities and photoelectrocatalytic performance, showing significant application advantages in environmental engineering and wastewater treatment.

[0020] The photoanode provided by this invention improves the efficiency of deep treatment of complex industrial wastewater by loading photoanode materials (including a WSe2 array layer and a Bi2O2Fe2O4 layer) onto an anode substrate. This invention employs a non-toxic, inexpensive, and highly resistant nano-metal WSe2 array and Bi2O2Fe2O4 semiconductor composite electrode. The electrode material has high adhesion, is not easily detached, and can be removed for cleaning, soaking, regeneration, and reuse, solving the problems of traditional suspended photocatalysts being difficult to recycle and prone to detachment.

[0021] More preferably, the anode substrate includes at least one of stainless steel mesh, titanium mesh, copper mesh, aluminum mesh, molybdenum mesh, nickel mesh, stainless steel sheet, foamed nickel, foamed titanium, or foamed aluminum.

[0022] In this invention, the anode substrate is made of metallic material, and the substrate shape is sheet-like, mesh-like, or foam mesh-like. It has a unique porous structure, stable physicochemical properties, and good conductivity. It is stable in different electrolytes. The porous structure not only increases the surface area of ​​the anode, but also facilitates the reaction between ions in the electrolyte and the active materials on the electrode, thereby improving the activity of the photoelectrocatalytic reaction and enhancing the wastewater treatment effect of the photoelectrocatalytic advanced oxidation system.

[0023] More preferably, the anode substrate has a length of 50mm to 100mm, a width of 200mm to 400mm, and a thickness of 3mm to 5mm.

[0024] This invention utilizes an inexpensive anode substrate with a large specific surface area and stable physicochemical properties as a support substrate for a photoelectrocatalyst, effectively leveraging the synergistic effect of photoelectrocatalysis and saving wastewater treatment costs.

[0025] More preferably, the thickness of the WSe2 array layer is 3μm~5μm.

[0026] It should be noted that in this invention, the WSe2 array layer is arranged as a single-layer WSe2 array, and the thickness of the WSe2 array layer is the length of the WSe2 array.

[0027] More preferably, the thickness of the Bi2O2Fe2O4 layer is 80nm~200nm.

[0028] More preferably, the Bi2O2Fe2O4-containing layer further includes carbon nanofibers.

[0029] Carbon nanofibers possess excellent toughness, mechanical strength, adhesion, and conductivity. They can increase the adhesion between the active materials (WSe2 array and Bi2O2Fe2O4) and the anode substrate in photoelectrode materials, preventing the active materials from falling off the anode substrate and improving the stability of the photoelectrode. At the same time, carbon nanofibers have good conductivity and will not reduce the electron transport performance of the photoelectrode, which is beneficial to improving the photoelectrocatalytic activity of the electrode.

[0030] More preferably, the carbon nanofibers have a diameter of 150 nm to 200 nm and a length of 5 μm to 20 μm.

[0031] More preferably, the mass ratio of WSe2 to Bi2O2Fe2O4 in the photoelectric anode material is 200:(10~50).

[0032] More preferably, the mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofibers in the photoelectric anode material is 200:(10~50):(0.8~1.6), and even more preferably 200:(20~40):(1~1.4).

[0033] By limiting the thickness of the WSe2 array layer and the Bi2O2Fe2O4 layer, as well as the amount of WSe2 and Bi2O2Fe2O4, this invention can better leverage the synergistic effect of the two, achieving both good photoresponse capability and good electrocatalytic performance.

[0034] More preferably, the WSe2 has n-type semiconductor characteristics and a particle size of 10nm~200nm.

[0035] More preferably, the preparation method of Bi2O2Fe2O4 includes the following steps:

[0036] Fe2O4 2- Salt, bismuth salt, emulsifier, ammonium acetate solution and acidity regulator are added to water, and hydrolysis is carried out under acidic conditions to effectively avoid the generation of a large number of non-hydrolysis products (such as ferric hydroxide, ferrous hydroxide, etc.), resulting in a suspension; after adjusting the pH of the suspension to weak alkalinity, a first hydrothermal reaction is carried out to obtain Bi2O2Fe2O4.

[0037] In this invention, Fe2O4 2- Under ammonium acetate and acidic conditions, bismuth salts undergo a hydrolysis reaction to form a white suspension of Bi(OH)Fe2O4. The emulsifier can effectively reduce the number of agglomerated particles. Then, under weakly alkaline conditions, a first hydrothermal reaction is carried out to promote the continuous substitution and overlapping of the axial lattice. Bismuth salts and Bi(OH)Fe2O4 continue to react, eventually generating nano-sized Bi2O2Fe2O4.

[0038] More preferably, the Fe2O4 2- Salts include sodium ferrite.

[0039] More preferably, the bismuth salt includes bismuth nitrate.

[0040] More preferably, the emulsifier includes polyvinyl alcohol.

[0041] More preferably, the concentration of the ammonium acetate solution is 1.7M to 2.3M.

[0042] More preferably, the acidity regulator comprises a 1.7M to 2.3M acetic acid solution.

[0043] More preferably, the Fe2O4 2- The mass ratio of salt, bismuth salt, emulsifier, ammonium acetate solution and water is (2~8):(4~16):(0.5~1):(0.02~0.5):(100~160), and more preferably (3~7):(8~12):(0.6~0.9):(0.1~0.3):(120~150).

[0044] More preferably, the acidic condition is pH=3~5.

[0045] More preferably, the hydrolysis reaction is carried out at a temperature of 20°C to 30°C and for a reaction time of 30 min to 50 min.

[0046] More preferably, urea is used to adjust the pH of the suspension to 7-8.

[0047] More preferably, the temperature of the first hydrothermal reaction is 180℃~220℃, and the reaction time is 8h~10h.

[0048] For example, after the first hydrothermal reaction is completed, the process also includes: cooling to room temperature, solid-liquid separation, washing and drying the solid to obtain Bi2O2Fe2O4.

[0049] More preferably, the particle size of the Bi2O2Fe2O4 is 10nm~150nm.

[0050] Preferably, the method for preparing the photoanode includes the following steps:

[0051] Sa, the anode substrate is immersed in a mixture of WSe2 and water to carry out a second hydrothermal reaction to obtain the primary electrode;

[0052] Sb, the primary electrode is immersed in a mixture of WSe2, silane coupling agent and cosolvent, and a third hydrothermal reaction is carried out to form a WSe2 array layer, thus obtaining a WSe2 array electrode;

[0053] Sc, a mixture of Bi2O2Fe2O4, binder and co-solvent is coated onto the WSe2 array electrode, and then calcined to form a Bi2O2Fe2O4 layer, thus obtaining a photoanode.

[0054] The present invention provides a method for preparing a photoanode, which employs a sol-gel method to load and grow photoanode material onto an anode substrate, and then calcines it to utilize the annealing properties to obtain the photoanode. The invention first uses a second hydrothermal reaction to form a primary electrode; then, under the action of a cosolvent, hydrothermal action allows nano-WSe2 to enter the surface of the primary electrode, continuously nucleating and diffusing, and adsorbing and coupling under the action of a silane coupling agent, depositing to form a WSe2 array layer, thus obtaining a WSe2 array electrode; finally, the sol-gel method is again used to coat Bi2O2Fe2O4 onto the surface of the WSe2 array electrode, and calcination is performed to form a Bi2O2Fe2O4-containing layer, thus obtaining the photoanode.

[0055] For example, in Sa, before impregnation, the process includes: placing the anode substrate in acetone and water in sequence, sonicating for 10 to 15 minutes respectively, and then drying.

[0056] This invention first pre-treats the anode substrate, which can effectively remove impurities and oil stains on the surface of the anode substrate and increase the adhesion of subsequent photoelectrocatalytic materials to the electrode substrate surface.

[0057] More preferably, in Sa, the mass ratio of WSe2 to water is (1~4):(80~100).

[0058] More preferably, in Sa, the immersion time is 30 min to 60 min.

[0059] More preferably, in Sa, the temperature of the second hydrothermal reaction is 100℃~120℃, and the reaction time is 25min~40min.

[0060] Under specific second hydrothermal reaction conditions, this invention enables WSe2 to be uniformly diffused and distributed on the surface of the anode substrate while ensuring that the crystal form of WSe2 remains unchanged, and at the same time improves the adhesion and bonding force of WSe2 on the anode substrate.

[0061] More preferably, in Sb, the silane coupling agent includes KH560.

[0062] More preferably, in Sb and Sc, the co-solvent comprises 40wt% to 60wt% of a polyvinylpyrrolidone aqueous solution.

[0063] Povidone aqueous solution is an ionic liquid, which can increase the solubility of the system, reduce interfacial tension, and facilitate the full progress of the third hydrothermal reaction.

[0064] More preferably, in Sb, the mass ratio of WSe2, silane coupling agent and cosolvent is (2~5):(1~4):(10~20).

[0065] More preferably, in Sb, the temperature of the third hydrothermal reaction is 80℃~120℃, and the reaction time is 4h~8h.

[0066] It should be noted that the present invention does not limit the amount of photoanode and mixed solution in Sa, as long as the mixed solution can immerse the anode substrate; the present invention also does not limit the amount of primary electrode and mixed solution in Sb, as long as the mixed solution can immerse the primary electrode.

[0067] More preferably, in Sc, the mixture also includes carbon nanofibers.

[0068] More preferably, in Sc, the adhesive comprises polyethylene dioxythiophene.

[0069] Polyvinyl dioxythiophene (PEDOT) is an electrode material adhesive with electronic conductivity. In this invention, it can improve the adhesion of Bi2O2, Fe2O4 and carbon nanofibers on WSe2 array electrodes.

[0070] More preferably, in Sc, the mass ratio of Bi2O2Fe2O4, binder and co-solvent is (6~32):(1~8):(10~80), more preferably (10~28):(2~7):(25~65), and even more preferably (15~22):(3~6):(30~50).

[0071] More preferably, in Sc, the coating thickness is 80nm~200nm.

[0072] For example, in Sc, after coating and before calcination, it also includes natural drying for 4 to 10 minutes.

[0073] More preferably, in Sc, the calcination temperature is 160℃~260℃ (more preferably 180℃~240℃), and the calcination time is 80min~120min.

[0074] Under specific calcination conditions, the Bi2O2Fe2O4 layer solidifies, and the Bi2O2Fe2O4 lattice gradually diffuses and tends to equilibrium, increasing the adhesion and bonding force of the Bi2O2Fe2O4 layer on the WSe2 array electrode.

[0075] In the example, Sc, calcination also includes: cooling to room temperature.

[0076] Preferably, the photocathode includes at least one of a graphite electrode, a carbon rod electrode, a graphite fiber felt electrode, or a coated metal electrode.

[0077] More preferably, the photocathode comprises at least one of carbon cloth, carbon fiber felt, titanium sheet, titanium mesh, platinum sheet, or platinum mesh.

[0078] Preferably, the photoanode and the photocathode are of the same size.

[0079] This invention selects corrosion-resistant electrodes with sheet-like or mesh-like structures as photocathodes, which have low overpotentials, high hydrogen evolution potentials, and are less prone to hydrogen gas generation and hydrogen embrittlement. The preferred photocathode of this invention can fully utilize energy, reduce electricity consumption, and has the advantages of low-carbon emission reduction.

[0080] Preferably, the volume of the electrolytic cell is 20L to 150L.

[0081] Preferably, the electrolytic cell is equipped with a stirring device.

[0082] A stirring device can make the photoelectrocatalytic advanced oxidation reaction proceed more fully.

[0083] For example, the light source uses a simulated sunlight system.

[0084] Preferably, the power supply is a DC power supply of 80V~220V.

[0085] In this invention, the current of the DC regulated power supply can be set as a linear function with time as the variable, thereby reducing degradation energy consumption and improving the current efficiency of the photoelectrocatalytic advanced oxidation system.

[0086] Preferably, the volume of the biofilm tank is 250L~600L.

[0087] Preferably, the biofilm tank is equipped with a stirring device.

[0088] For example, the biofilm tank may be made of at least one of the following materials: metal, enamel, plexiglass, plastic, or acrylic.

[0089] Preferably, the upper side wall of the biofilm tank is provided with an air outlet for discharging gas.

[0090] Preferably, the porous biofilm carrier is at least one of polyurethane sponge, polyurethane hydrogel, polypropylene filler, or polyethylene filler.

[0091] Preferably, the porous biomembrane carrier has a pore size of 300 nm to 600 nm and a specific gravity of 0.8 g / cm³. 3 ~0.85g / cm 3 Specific surface area is 1100 mm² 2 / g~1375mm 2 / g.

[0092] The preferred biofilm carrier of this invention has a porous and permeable structure, which increases the specific surface area and makes it easier for microorganisms to attach, thereby forming a dense biofilm.

[0093] For example, porous biofilm carriers require pretreatment before use, including the following steps:

[0094] The porous biofilm carrier was successively immersed in alkaline and acidic solutions and then washed.

[0095] For example, the size of the porous biofilm carrier is (5~20)mm×(5~20)mm×(5~20)mm, such as 5mm×5mm×5mm, 10mm×10mm×10mm, 15mm×15mm×15mm or 20mm×20mm×20mm.

[0096] For example, the alkaline solution is a 0.1 wt% sodium hydroxide solution or a 0.1 wt% potassium hydroxide solution, and the acid solution is a 0.1 wt% aqueous nitric acid solution.

[0097] For example, the soaking time using an alkaline solution is 1 to 2 hours, and the soaking time using a calcium solution is 1 to 2 hours.

[0098] For example, the cleaning can be ultrasonic cleaning, and after cleaning, the pH of the porous biofilm carrier is 6-7 (more preferably 6-6.5). Cleaning to near neutral pH is beneficial for subsequent microbial attachment to the porous biofilm carrier for growth and development, thereby forming a biofilm.

[0099] The purpose of using alkaline and acid washing in this invention is to remove impurities such as oil particles, organic and inorganic substances, and ash from the interior of the porous biofilm carrier. This invention does not impose special limitations on the amount of acid and alkaline solutions used; the porous biofilm carrier can be completely submerged.

[0100] Preferably, the amount of the porous biofilm carrier added is 3.5 g / L to 20 g / L, and more preferably 5 g / L to 15 g / L.

[0101] Preferably, the amount of activated sludge added is 0.1 kg / L to 0.6 kg / L, and more preferably 0.2 kg / L to 0.4 kg / L.

[0102] Preferably, the coconut shell powder has a particle size of 450 mesh to 600 mesh.

[0103] Preferably, the amount of coconut shell powder added is 0.1g / L to 0.4g / L.

[0104] Preferably, a water storage device is also connected between the photoelectrocatalytic advanced oxidation system and the suspended packing biofilm reactor;

[0105] The inlet of the water storage device is connected to the outlet of the electrolysis cell, and the outlet of the water storage device is connected to the inlet of the biofilm tank.

[0106] This invention addresses the differences in influent and effluent control and effective volume between the photoelectrocatalytic advanced oxidation system and the MBBR. By adding a water storage device between the two for buffering, the simultaneous operation of the photoelectrocatalytic advanced oxidation system and the MBBR can be achieved. Wastewater treatment solutions can be tailored to different water bodies, and the start-up time and power of pumps in different stages can be adjusted. The peristaltic pump can operate around the clock, significantly improving the efficiency of wastewater treatment.

[0107] Preferably, a peristaltic pump is connected between the outlet of the electrolytic cell and the inlet of the biofilm tank, and a peristaltic pump is connected between the outlet of the biofilm tank and the inlet of the electrolytic cell, respectively, to control the inlet flow rate and the outlet flow rate.

[0108] More preferably, a peristaltic pump is connected between the outlet of the electrolytic cell and the inlet of the water storage device, and a peristaltic pump is connected between the outlet of the water storage device and the inlet of the biofilm tank.

[0109] This invention can control the inlet and outlet flow rates through a peristaltic water pump, thereby adjusting the treatment efficiency of pollutants in the water, shortening the time for photoelectrocatalytic advanced oxidation and biofilm treatment, and achieving the rational utilization of energy.

[0110] Secondly, the present invention provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, employing the aforementioned photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system, comprising the following steps:

[0111] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0112] The wastewater to be treated and activated sludge are introduced into the biofilm tank for the first aerobic reaction; then porous biofilm carrier and coconut shell powder are added, and the wastewater to be treated and the treated wastewater are intermittently introduced for the second aerobic reaction. After 5 to 10 days, the treated purified water is discharged.

[0113] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 2~7 and the conductivity is adjusted to 250μS / cm~1000μS / cm, the photoelectrocatalytic advanced oxidation system is turned on to carry out photoelectrocatalytic treatment, and the photoelectrocatalytic purified effluent is obtained;

[0114] S3, the photoelectric treated purified water is introduced into the biofilm tank to carry out the third aerobic reaction, and the purified water of the biofilm tank is obtained.

[0115] S4, the purified water from the biofilm tank is returned to the electrolysis tank, and the operation of steps S2 to S3 is repeated until purified water that meets the discharge standards is obtained.

[0116] The wastewater treatment method coupled with photoelectrocatalytic advanced oxidation and suspended packing biofilm reactor provided by this invention involves adding nano-coconut shell powder to activated sludge during the MBBR microbial acclimatization stage. Utilizing the microporous structure's adsorption and fixation of nutrients, this promotes the growth and metabolism of microorganisms on the activated sludge and porous biofilm carrier, accelerating microbial growth and biofilm formation. Through photoelectrocatalytic treatment, not only are complex organic matter in the water decomposed, but the biodegradability of the water is also improved, effectively enhancing the subsequent deep treatment of wastewater by the MBBR. Combined with the adsorption of metal ions and toxic pollutants by coconut shell powder, the purification and cleaning efficiency of pollutants in the water is increased. Finally, through end-of-pipe recirculation, stubborn substances in the water can be repeatedly treated until the discharge meets standards.

[0117] The wastewater treatment method coupled with photoelectrocatalytic advanced oxidation and suspended packing biofilm reactor provided by this invention has mild reaction conditions, is green and low-carbon, overcomes the defects of high energy consumption and limited catalyst circulation of traditional advanced oxidation technology, and greatly shortens the treatment cycle.

[0118] Furthermore, this invention utilizes a photoanode loaded with a Bi2O2Fe2O4 / WSe2 array in an electrolytic cell. Through photoelectrocatalytic advanced oxidation technology, the activity of both photocatalytic and electrocatalytic oxidation reactions is enhanced. The various components and materials exhibit synergistic effects, improving the deep treatment efficiency of complex water qualities. The photoelectrocatalytic advanced oxidation system possesses extremely strong oxidation-reduction capabilities under the influence of an external electric field and light radiation. The photoanode loses electrons and generates holes under the excitation of electrical energy and light radiation. These holes exhibit strong oxidizing properties and can directly react with pollutants or react with water molecules to form hydroxyl radicals (·OH) for indirect oxidation of pollutants. Meanwhile, electrons, under the influence of an external electric field, directionally migrate to and accumulate at the cathode. These strongly reducing electrons can not only directly catalyze the precipitation of heavy metal ions but also react with water to generate superoxide radicals (·O2). 2- ), indirectly oxidizing pollutants.

[0119] Preferably, in S1, the temperature of the first aerobic reaction is 20℃~35℃, and the ventilation rate is 100m³ / h. 3 / h~150m 3 / h, with a time range of 30h to 90h.

[0120] Preferably, in S1, the temperature of the second aerobic reaction is 20℃~35℃, the dissolved oxygen concentration is 3mg / L~6mg / L, and the time is 7d~9d.

[0121] For example, in S1, during the second aerobic reaction process, the water level in the biofilm tank remains unchanged during the intermittent introduction of wastewater to be treated and the discharge of treated wastewater; the intermittent introduction of wastewater to be treated and the discharge of treated wastewater lasts for 12h to 48h.

[0122] In the second aerobic reaction process of this invention S1, the liquid level can be kept constant by simultaneously opening both the inlet and outlet of the biofilm tank. The inlet and outlet of the biofilm tank are opened for 12-48 hours and closed for 12-48 hours, until the biofilm growth and biological acclimatization of the porous biofilm carrier are completed after 5-10 days. During the second aerobic reaction, some microorganisms undergo denitrification in the anoxic environment inside the pores of the porous biofilm carrier, while others undergo nitrification of nitrogenous substances in the aerobic environment outside the pores. After the second aerobic reaction, the COD of the treated purified water can reach below 80 mg / L.

[0123] Preferably, in S1, after the second aerobic reaction is completed, the thickness of the biofilm on the porous biofilm carrier is 1.8 mm to 2 mm.

[0124] The basic principle of biofilm formation is to attach bacteria and other microorganisms from activated sludge to a porous biofilm carrier, where they continuously grow and develop to form a biofilm. These biofilms can decompose organic impurities in wastewater. As wastewater passes through the packing layer (porous biofilm carrier), the organic pollutants in the water are gradually decomposed by the microorganisms on the biofilm.

[0125] Preferably, in S1~S2, the wastewater to be treated has a COD of 150mg / L~12000mg / L, an ammonia nitrogen value of 50mg / L~390mg / L, a BOD of 70mg / L~410mg / L, a suspended solids content of 100mg / L~190mg / L, and a heavy metal ion content of 10mg / L~180mg / L.

[0126] For example, in S2, the pH of the wastewater to be treated is adjusted using a 0.1 wt% sodium hydroxide solution, a 0.1 wt% hydrochloric acid aqueous solution, or a 0.1 wt% nitric acid aqueous solution, and the conductivity of the wastewater to be treated is adjusted using sodium sulfate or potassium sulfate. This invention adjusts the wastewater to a specific pH and conductivity range, which is beneficial for the smooth progress of subsequent photoelectrocatalytic treatment, while also saving electrical energy.

[0127] Preferably, in S2, the photoelectrocatalytic treatment time is 30 min to 120 min.

[0128] Preferably, in S2, the COD of the photoelectric treated purified water is 105 mg / L to 820 mg / L, the ammonia nitrogen value is 26 mg / L to 160 mg / L, the BOD is 40 mg / L to 110 mg / L, the suspended solids content is 50 mg / L to 105 mg / L, and the heavy metal ion content is 6 mg / L to 60 mg / L.

[0129] Preferably, in S3, the temperature of the third aerobic treatment is 20℃~35℃, the dissolved oxygen concentration is 3mg / L~6mg / L, and the time is 12h~48h.

[0130] Preferably, in S3, the COD of the effluent purified by the biofilm tank is 10 mg / L to 180 mg / L, the ammonia nitrogen value is 10 mg / L to 63 mg / L, the BOD is 15 mg / L to 80 mg / L, and the heavy metal ion content is 2 mg / L to 10 mg / L.

[0131] Preferably, in S3, the purified water that meets the emission standards has a COD of less than 60 mg / L, an ammonia nitrogen value of less than 15 mg / L, a BOD of less than 20 mg / L, a suspended solids content of less than 20 mg / L, and a heavy metal ion content of less than 2 mg / L. Attached Figure Description

[0132] Figure 1 This is a schematic diagram of the coupled system of photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor in an embodiment of the present invention; wherein, 1 represents the photoelectrocatalytic advanced oxidation system, 101 represents the photoanode, 102 represents the photocathode, 103 represents the electrolytic cell, 1031 represents the inlet of the electrolytic cell, 1032 represents the outlet of the electrolytic cell, 104 represents the power source, and 105 represents the light source; 2 represents the suspended packing biofilm reactor, 201 represents the biofilm tank, 2011 represents the inlet of the biofilm tank, 2012 represents the outlet of the biofilm tank, 2013 represents the air outlet of the biofilm tank, 202 represents the aeration device, 203 represents activated sludge, 204 represents the porous biofilm carrier, and 205 represents coconut shell powder; 3 represents the water storage device, and 4 represents the peristaltic pump;

[0133] Figure 2 This is a SEM image of Bi2O2Fe2O4 in Example 3 of the present invention;

[0134] Figure 3 This is a SEM image of the WSe2 array in Embodiment 3 of the present invention;

[0135] Figures 4-5 This is a SEM image of the Bi2O2Fe2O4 / WSe2 array in Embodiment 3 of the present invention;

[0136] Figure 6 The images show the XRD patterns of Bi2O2Fe2O4, Bi2O2Fe2O4 / WSe2 array, and WSe2-Bi2O2Fe2O4 nanocomposite in Example 3 of this invention. Detailed Implementation

[0137] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0138] Please see Figure 1 The present invention provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system, comprising: a photoelectrocatalytic advanced oxidation system 1 and a suspended packing biofilm reactor 2;

[0139] The photoelectrocatalytic advanced oxidation system 1 includes a photoanode 101, a photocathode 102, an electrolytic cell 103, a power supply 104, and a light source 105;

[0140] The photoanode 101 and the photocathode 102 are located in the electrolytic cell 103, and the photoanode 101 and the photocathode 102 are respectively connected to the power supply 104 through wires; the light source 105 is located outside the electrolytic cell 103 and is used to irradiate the electrolytic cell 103 with light.

[0141] The suspended packing biofilm reactor 2 includes a biofilm tank 201, an aeration device 202, activated sludge 203, a porous biofilm carrier 204, and coconut shell powder 205.

[0142] The aeration device 202 is located below the biofilm tank 201 and is used to create an aerobic environment; the activated sludge 203, the porous biofilm carrier 204 and the coconut shell powder 205 are located in the biofilm tank 201.

[0143] The inlet 2011 of the biofilm tank 201 is connected to the outlet 1032 of the electrolysis tank 103, and the outlet 2012 of the biofilm tank 201 is connected to the inlet 1031 of the electrolysis tank 103, for recirculation and multiple cycles.

[0144] In some embodiments, the photoanode 101 and the photocathode 102 are the same size.

[0145] In some embodiments, the electrolytic cell 103 is equipped with a stirring device.

[0146] In some embodiments, the light source 105 employs a simulated sunlight system.

[0147] In some embodiments, the biofilm tank 201 is equipped with a stirring device.

[0148] In some embodiments, the upper sidewall of the biofilm tank 201 is provided with an air outlet 2013 for discharging gas.

[0149] In some embodiments, a water storage device 3 is also connected between the photoelectrocatalytic advanced oxidation system 1 and the suspended packing biofilm reactor 2;

[0150] The inlet of the water storage device 3 is connected to the outlet 1032 of the electrolysis cell 103, and the outlet of the water storage device 3 is connected to the inlet 2011 of the biofilm tank 201.

[0151] In some embodiments, a peristaltic pump 4 is connected between the outlet 1032 of the electrolytic cell 103 and the inlet 2011 of the biofilm tank 201, and a peristaltic pump 4 is connected between the outlet 2012 of the biofilm tank 201 and the inlet 1031 of the electrolytic cell 103, respectively, for controlling the inlet flow rate and the outlet flow rate.

[0152] In some embodiments, a peristaltic pump 4 is connected between the outlet 1032 of the electrolytic cell 103 and the inlet of the water storage device 3, and a peristaltic pump 4 is connected between the outlet of the water storage device 3 and the inlet 2011 of the biofilm tank 201.

[0153] In this invention, the visible light radiation is provided by the light source of the HSX-F300 simulated sunlight system, and the aeration device is the RB-71D sewage aeration blower with adjustable power (100W~750W).

[0154] In this invention, all materials unless otherwise specified are commercially available products. All water used in this invention is deionized water. The wastewater used in this invention is taken from industrial park wastewater. The activated sludge in this invention is derived from activated sludge in the aerobic tank of a wastewater treatment plant, serving as the microbial source.

[0155] Example 1

[0156] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system (see...). Figure 1 It includes: a photoelectrocatalytic advanced oxidation system 1, a suspended packing biofilm reactor 2, and a water storage device 3.

[0157] The photoelectrocatalytic advanced oxidation system 1 includes a photoanode 101, a photocathode 102, an electrolytic cell 103, a power supply 104, and a light source 105. The photoanode 101 and photocathode 102 are located in the electrolytic cell 103, and are respectively connected to the power supply 104 via wires; the light source 105 is located outside the electrolytic cell 103 and is used to irradiate the electrolytic cell 103 with light.

[0158] The photoanode 101 and photocathode 102 are the same size. The electrolytic cell 103 is equipped with a stirring device.

[0159] The suspended packing biofilm reactor 2 includes a biofilm tank 201, an aeration device 202, activated sludge 203, a porous biofilm carrier 204, and coconut shell powder 205. The aeration device 202 is located below the biofilm tank 201 and is used to create an aerobic environment; the activated sludge 203, the porous biofilm carrier 204, and the coconut shell powder 205 are located in the biofilm tank 201.

[0160] The biofilm tank 201 is equipped with a stirring device. The upper side wall of the biofilm tank 201 is provided with an air outlet 2013 for discharging gas.

[0161] The inlet of the water storage device 3 is connected to the outlet 1032 of the electrolysis cell 103, and the outlet of the water storage device 3 is connected to the inlet 2011 of the biofilm tank 201. The outlet 2012 of the biofilm tank 201 is connected to the inlet 1031 of the electrolysis cell 103 for recirculation and multiple cycles. A peristaltic pump 4 is connected between the outlet 1032 of the electrolysis cell 103 and the inlet of the water storage device 3, between the outlet of the water storage device 3 and the inlet 2011 of the biofilm tank 201, and between the outlet 2012 of the biofilm tank 201 and the inlet 1031 of the electrolysis cell 103, respectively, to control the inlet and outlet flow rates.

[0162] The photoanode 101 includes an anode substrate and a photoanode material loaded on the anode substrate. The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer. The Bi2O2Fe2O4 layer further includes carbon nanofibers with a diameter of 150 nm × 5 μm. The mass ratio of WSe2, Bi2O2Fe2O4, and carbon nanofibers in the photoanode material is 200:10:0.8. The anode substrate is a 50 mm × 200 mm × 3 mm molybdenum mesh, the thickness of the WSe2 array layer is 3 μm, and the thickness of the Bi2O2Fe2O4 layer is 80 nm.

[0163] The above-mentioned method for preparing a photoanode includes the following steps:

[0164] Preparation of SI, Bi₂O₂Fe₂O₄:

[0165] Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 2.3M ammonium acetate solution and 2.3M acetic acid solution were added to water. The mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution and water was 2:4:0.5:0.02:100. At this time, the pH of the system was 3. After hydrolysis reaction at 20℃ for 45 min, a suspension was obtained.

[0166] The pH of the suspension was adjusted to 7.1 using urea, and the first hydrothermal reaction was carried out in a high-pressure reactor at 180℃. After holding at this temperature for 10 hours, the mixture was cooled to room temperature, and the solid and liquid were separated. The solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 14nm.

[0167] SII: The anode substrate is placed in acetone and water in sequence, sonicated for 10 min each, and then naturally dried. It is then immersed in a mixture of WSe2 (average particle size of 12 nm) and water (mass ratio of WSe2 to water is 1:80) for 30 min. Then it is taken out and carried out in a 100℃ reactor for a second hydrothermal reaction. After holding at the temperature for 40 min, the primary electrode is obtained.

[0168] SIII. The primary electrode is immersed in a mixture of WSe2, KH560 and 60wt% of a povidone aqueous solution. The mass ratio of WSe2, KH560 and the povidone aqueous solution is 2:1:10. The third hydrothermal reaction is carried out in a reactor at 80℃ and kept at this temperature for 7 hours to form a WSe2 array layer. After cooling to room temperature, the electrode is washed with water and dried to obtain the WSe2 array electrode.

[0169] SIV, using a coating machine, a mixture of Bi2O2Fe2O4, carbon nanofibers, PEDOT and 60wt% povidone aqueous solution (the mass ratio of Bi2O2Fe2O4, carbon nanofibers, PEDOT and povidone aqueous solution is 6:1:14) is coated onto the WSe2 array electrode. After natural drying for 4 min, it is calcined at 165℃ for 120 min to form a Bi2O2Fe2O4 layer. After cooling to room temperature, a photoanode containing Bi2O2Fe2O4 / WSe2 array is obtained.

[0170] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0171] The photocathode 102 is a tungsten alloy electrode with the same dimensions as the photoanode 101. The electrolytic cell 103 has a volume of 20L, and the power supply 104 is an 80V DC power supply.

[0172] The biofilm tank 201 has a volume of 250L, and the porous biofilm carrier has a pore size of 300nm and a specific gravity of 0.8g / cm³. 3 The polyurethane hydrogel, porous biofilm carrier added at a rate of 4 g / L, activated sludge added at a rate of 0.15 kg / L, and 450-mesh coconut shell powder added at a rate of 0.1 g / L.

[0173] Example 2

[0174] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system (see...). Figure 1It includes: a photoelectrocatalytic advanced oxidation system 1, a suspended packing biofilm reactor 2, and a water storage device 3.

[0175] The positional relationship and connection of the photoelectrocatalytic advanced oxidation system 1, the suspended packing biofilm reactor 2, and the water storage device 3 are the same as in Example 1, and will not be repeated here.

[0176] The photoanode 101 includes an anode substrate and a photoanode material loaded on the anode substrate. The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer. The Bi2O2Fe2O4 layer further includes carbon nanofibers with a diameter of 160 nm × 10 μm. The mass ratio of WSe2, Bi2O2Fe2O4, and carbon nanofibers in the photoanode material is 200:15:1. The anode substrate is an 80 mm × 250 mm × 4 mm molybdenum mesh. The thickness of the WSe2 array layer is 4 μm, and the thickness of the Bi2O2Fe2O4 layer is 100 nm.

[0177] The above-mentioned method for preparing a photoanode includes the following steps:

[0178] Preparation of SI, Bi₂O₂Fe₂O₄:

[0179] Add Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 2M ammonium acetate solution, and 2M acetic acid solution to water. The mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution, and water is 3:6:0.6:0.15:110. At this point, the pH of the system is 4. After hydrolysis at 25℃ for 40 min, a suspension is obtained.

[0180] The pH of the suspension was adjusted to 7.5 using urea, and the first hydrothermal reaction was carried out in a high-pressure reactor at 190℃. After holding at this temperature for 9.5 hours, the mixture was cooled to room temperature, and the solid and liquid were separated. The solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 60 nm.

[0181] SII: The anode substrate is placed in acetone and water in sequence, sonicated for 15 min each, and then naturally dried. It is then immersed in a mixture of WSe2 (average particle size of 60 nm) and water (mass ratio of WSe2 to water of 2:85) for 40 min. Then it is taken out and carried out in a reactor at 110℃ for a second hydrothermal reaction. After holding at the temperature for 30 min, the primary electrode is obtained.

[0182] SIII. The primary electrode is immersed in a mixture of WSe2, KH560 and 50wt% povidone aqueous solution, with a mass ratio of WSe2, KH560 and povidone aqueous solution of 3:2:12. The third hydrothermal reaction is carried out in a reactor at 90℃ and kept at the temperature for 7h to form a WSe2 array layer. After cooling to room temperature, it is washed with water and dried to obtain the WSe2 array electrode.

[0183] SIV, using a coating machine, a mixture of Bi2O2Fe2O4, carbon nanofibers, PEDOT and 50wt% povidone aqueous solution (the mass ratio of Bi2O2Fe2O4, carbon nanofibers, PEDOT and povidone aqueous solution is 10:3:30) is coated onto the WSe2 array electrode. After natural drying for 6 min, it is calcined at 180℃ for 110 min to form a Bi2O2Fe2O4 layer. After cooling to room temperature, a photoanode containing Bi2O2Fe2O4 / WSe2 array is obtained.

[0184] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0185] The photocathode 102 is a titanium mesh of the same size as the photoanode 101, the electrolytic cell 103 has a volume of 100L, and the power supply 104 is an 80V DC power supply.

[0186] The biofilm tank 201 has a volume of 380L, and the porous biofilm carrier has a pore size of 400nm and a specific gravity of 0.84g / cm³. 3 The amount of polyurethane sponge, porous biofilm carrier added is 8 g / L, activated sludge added is 0.25 kg / L, and 500-mesh coconut shell powder added is 0.2 g / L.

[0187] Example 3

[0188] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system (see...). Figure 1 It includes: a photoelectrocatalytic advanced oxidation system 1, a suspended packing biofilm reactor 2, and a water storage device 3.

[0189] The positional relationship and connection of the photoelectrocatalytic advanced oxidation system 1, the suspended packing biofilm reactor 2, and the water storage device 3 are the same as in Example 1, and will not be repeated here.

[0190] The photoanode 101 includes an anode substrate and a photoanode material loaded on the anode substrate. The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer. The Bi2O2Fe2O4 layer further includes carbon nanofibers with a diameter of 180 nm × 15 μm. The mass ratio of WSe2, Bi2O2Fe2O4, and carbon nanofibers in the photoanode material is 200:35:1.3. The anode substrate is 100 mm × 300 mm × 3 mm nickel foam, the thickness of the WSe2 array layer is 4 μm, and the thickness of the Bi2O2Fe2O4 layer is 180 nm.

[0191] The above-mentioned method for preparing a photoanode includes the following steps:

[0192] Preparation of SI, Bi₂O₂Fe₂O₄:

[0193] Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 1.7M~2.3M ammonium acetate solution and 1.7M~2.3M acetic acid solution were added to water. The mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution and water was 6:12:0.8:0.3:140. At this time, the pH of the system was 4. After hydrolysis reaction at 25℃ for 40 min, a suspension was obtained.

[0194] The pH of the suspension was adjusted to 7.8 using urea, and the first hydrothermal reaction was carried out in a high-pressure reactor at 200℃. After holding at this temperature for 9 hours, the mixture was cooled to room temperature, and the solid and liquid were separated. The solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 120nm.

[0195] The obtained product was subjected to electron microscopy and X-ray diffraction tests, and the results are as follows: Figure 2 and Figure 6 As shown.

[0196] SII: The anode substrate is placed in acetone and water in sequence, sonicated for 12 min each, and then naturally dried. It is then immersed in a mixture of WSe2 (average particle size of 160 nm) and water (mass ratio of WSe2 to water is 3:90) for 50 min. Then it is taken out and carried out in a reactor at 110℃ for a second hydrothermal reaction. After holding at the temperature for 30 min, the primary electrode is obtained.

[0197] SIII. The primary electrode is immersed in a mixture of WSe2, KH560 and 50wt% povidone aqueous solution, with a mass ratio of WSe2, KH560 and povidone aqueous solution of 4:3:15. The third hydrothermal reaction is carried out in a reactor at 110℃ and kept at this temperature for 6 hours to form a WSe2 array layer. After cooling to room temperature, the electrode is washed with water and dried to obtain the WSe2 array electrode.

[0198] The obtained product was subjected to scanning electron microscopy, and the results are as follows: Figure 3 As shown.

[0199] SIV, using a coating machine, a mixture of Bi2O2Fe2O4, carbon nanofibers, PEDOT and 50wt% povidone aqueous solution (the mass ratio of Bi2O2Fe2O4, carbon nanofibers, PEDOT and povidone aqueous solution is 28:6:60) is coated onto the WSe2 array electrode. After natural drying for 8 min, it is calcined at 240℃ for 100 min to form a Bi2O2Fe2O4 layer. After cooling to room temperature, a photoanode containing Bi2O2Fe2O4 / WSe2 array is obtained.

[0200] The surface of the above-prepared material was subjected to scanning electron microscopy and X-ray diffraction tests, and the results are as follows: Figures 4-5 and Figure 6 As shown; to further verify the structure of the Bi2O2Fe2O4 / WSe2 array, X-ray diffraction tests were performed on a mixture of WSe2 and Bi2O2Fe2O4 with a mass ratio of 200:30 (denoted as WSe2-Bi2O2Fe2O4), and the results are shown in the figure. Figure 6 As shown.

[0201] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0202] The photocathode 102 is a graphite felt electrode with the same dimensions as the photoanode 101. The electrolytic cell 103 has a volume of 120L, and the power supply 104 is a 100V DC power supply.

[0203] The biofilm tank 201 has a volume of 460L, and the porous biofilm carrier has a pore size of 500nm and a specific gravity of 0.83g / cm³. 3 The polyethylene packing material, porous biofilm carrier added at a rate of 12 g / L, activated sludge added at a rate of 0.35 kg / L, and 550-mesh coconut shell powder added at a rate of 0.3 g / L.

[0204] Example 4

[0205] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system (see...). Figure 1 It includes: a photoelectrocatalytic advanced oxidation system 1, a suspended packing biofilm reactor 2, and a water storage device 3.

[0206] The positional relationship and connection of the photoelectrocatalytic advanced oxidation system 1, the suspended packing biofilm reactor 2, and the water storage device 3 are the same as in Example 1, and will not be repeated here.

[0207] The photoanode 101 includes an anode substrate and a photoanode material loaded on the anode substrate. The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer. The Bi2O2Fe2O4 layer further includes carbon nanofibers with a diameter of 200 nm × 20 μm. The mass ratio of WSe2, Bi2O2Fe2O4, and carbon nanofibers in the photoanode material is 200:46:1.5. The anode substrate is a 100 mm × 400 mm × 4.5 mm titanium mesh. The thickness of the WSe2 array layer is 5 μm, and the thickness of the Bi2O2Fe2O4 layer is 200 nm.

[0208] The above-mentioned method for preparing a photoanode includes the following steps:

[0209] Preparation of SI, Bi₂O₂Fe₂O₄:

[0210] Add Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 1.7M ammonium acetate solution and 1.7M acetic acid solution to water. The mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution and water is 8:16:1:0.45:160. At this time, the pH of the system is 5. After hydrolysis reaction at 30℃ for 30 min, a suspension is obtained.

[0211] The pH of the suspension was adjusted to 7.5 using urea, and the first hydrothermal reaction was carried out in a high-pressure reactor at 220℃. After holding at this temperature for 8 hours, the mixture was cooled to room temperature, and the solid and liquid were separated. The solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 140nm.

[0212] SII: The anode substrate is placed in acetone and water in sequence, sonicated for 13 min each, and then naturally dried. It is then immersed in a mixture of WSe2 (average particle size of 190 nm) and water (mass ratio of WSe2 to water of 4:100) for 60 min. Then it is taken out and carried out in a 120℃ reactor for a second hydrothermal reaction. After holding at the temperature for 25 min, the primary electrode is obtained.

[0213] SIII. The primary electrode is immersed in a mixture of WSe2, KH560 and 40wt% of a povidone aqueous solution. The mass ratio of WSe2, KH560 and the povidone aqueous solution is 5:4:20. The third hydrothermal reaction is carried out in a reactor at 120℃ and kept at this temperature for 5 hours to form a WSe2 array layer. The electrode is then cooled to room temperature, washed with water and dried to obtain the WSe2 array electrode.

[0214] SIV, using a coating machine, a mixture of Bi2O2Fe2O4, carbon nanofibers, PEDOT and 40wt% povidone aqueous solution (the mass ratio of Bi2O2Fe2O4, carbon nanofibers, PEDOT and povidone aqueous solution is 32:8:77) is coated onto the WSe2 array electrode. After natural drying for 0 min, it is calcined at 260℃ for 80 min to form a Bi2O2Fe2O4 layer. After cooling to room temperature, a photoanode containing Bi2O2Fe2O4 / WSe2 array is obtained.

[0215] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0216] The photocathode 102 is a carbon rod with the same dimensions as the photoanode 101, the electrolytic cell 103 has a volume of 150L, ​​and the power supply 104 is a 180V DC power supply.

[0217] The biofilm tank 201 has a volume of 600L, and the porous biofilm carrier has a pore size of 600nm and a specific gravity of 0.85g / cm³. 3 The polypropylene packing material contains 18 g / L of porous biofilm carrier, 0.5 kg / L of activated sludge, and 0.4 g / L of 600-mesh coconut shell powder.

[0218] Example 5

[0219] This embodiment provides a photoelectrocatalytic advanced oxidation-suspension packing biofilm reactor coupling system, which is similar to Embodiment 3, except that the Bi2O2Fe2O4 in the Bi2O2Fe2O4 layer of the photoanode is replaced with ferrous tungstate.

[0220] The preparation method of the above photoanode is similar to that of Example 3, except that step S1 is omitted and Bi2O2Fe2O4 in SIV is replaced with an equal mass of ferrous tungstate. The remaining conditions are the same as in Example 3 and will not be repeated here.

[0221] Example 6

[0222] This embodiment provides a photoelectrocatalytic advanced oxidation-suspension packing biofilm reactor coupling system, which is similar to Embodiment 2, except that the Bi2O2Fe2O4 in the Bi2O2Fe2O4 layer of the photoanode is replaced with BiVO4.

[0223] The preparation method of the above photoanode is similar to that of Example 2, except that step S1 is omitted and Bi2O2Fe2O4 in SIV is replaced with an equal mass of BiVO4. The remaining conditions are the same as in Example 2 and will not be repeated here.

[0224] Example 7

[0225] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system, which is similar to Embodiment 3, except that the WSe2 in the WSe2 array layer of the photoanode is replaced with TiO2.

[0226] The preparation method of the above photoanode is similar to that of Example 3, except that WSe2 in SII~SIII is replaced with an equal mass of TiO2. The remaining conditions are the same as in Example 3 and will not be repeated.

[0227] Example 8

[0228] This embodiment provides a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system, which is similar to Embodiment 2, except that the WSe2 in the WSe2 array layer of the photoanode is replaced with ZnO.

[0229] The preparation method of the above photoanode is similar to that of Example 2, except that WSe2 in SII~SIII is replaced with an equal mass of ZnO. All other conditions are the same as in Example 2 and will not be repeated here.

[0230] Example 9

[0231] This embodiment provides a photoelectrocatalytic advanced oxidation-suspension packing biofilm reactor coupling system, which is similar to that of Embodiment 3, except that: the Bi2O2Fe2O4 in the Bi2O2Fe2O4 layer of the photoanode is replaced with ferrous tungstate, and the WSe2 in the WSe2 array layer is replaced with TiO2.

[0232] The preparation method of the above photoanode is similar to that of Example 3, except that step S1 is omitted, WSe2 in SII~SIII is replaced with an equal mass of TiO2, and Bi2O2Fe2O4 in SIV is replaced with an equal mass of ferrous tungstate. The remaining conditions are the same as in Example 3 and will not be repeated.

[0233] Comparative Example 1

[0234] This comparative example provides a photocatalytic-suspended packing biofilm reactor coupling system, similar to Example 3, except that the photoelectrocatalytic advanced oxidation system is replaced with a photocatalytic system that does not include a power source, photoanode, and photocathode (this can be understood as using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 3, but without power supply). All other conditions are the same as in Example 3 and will not be repeated.

[0235] Comparative Example 2

[0236] This comparative example provides an electrocatalytic-suspended packing biofilm reactor coupling system, similar to Example 3, except that the photoelectrocatalytic advanced oxidation system is replaced with an electrocatalytic system that does not contain a light source (this can be understood as using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 3, without turning on the light source during use). All other conditions are the same as in Example 3 and will not be repeated.

[0237] Comparative Example 3

[0238] This comparative example provides a suspended packing biofilm reactor, which is the same as the suspended packing biofilm reactor 2 in Example 3, and will not be described again.

[0239] Comparative Example 4

[0240] This comparative example provides a photoelectrocatalytic advanced oxidation system, which is the same as the photoelectrocatalytic advanced oxidation system 1 in Example 3, and will not be described again.

[0241] Comparative Example 5

[0242] This comparative example provides a coupled system of photoelectrocatalytic advanced oxidation and suspended packing biofilm reactor, similar to Example 3, except that the suspended packing biofilm reactor 2 does not contain coconut shell powder. All other conditions are the same as in Example 3 and will not be repeated.

[0243] Application Example 1

[0244] This application example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 1, including the following steps:

[0245] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0246] The wastewater to be treated and activated sludge were introduced into the biofilm tank (the mass ratio of wastewater to activated sludge was 3:1), and the aeration device 202 was turned on at 35°C and an aeration rate of 140 m³ / h. 3 After the first aerobic reaction was carried out for 30 hours at a dissolved oxygen concentration of 3 mg / L, a porous biofilm carrier and coconut shell powder were added, and a second aerobic reaction was carried out at 35℃ and a dissolved oxygen concentration of 3 mg / L. (During the second aerobic reaction, the wastewater to be treated and the treated wastewater were intermittently introduced and discharged. During this process, the water level in the biofilm tank remained unchanged. The inlet and outlet of the biofilm tank were opened for 12 hours and closed for 12 hours.) After 6 days, the biofilm thickness of the porous biofilm carrier was 1.8 mm, completing the biofilm growth and biological acclimatization of the porous biofilm carrier. The treated purified water was then discharged.

[0247] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 6 and the conductivity is adjusted to 250 μS / cm, the photoelectrocatalytic advanced oxidation system is turned on, and after photoelectrocatalytic treatment for 30 minutes, the photoelectrocatalytic purified effluent is obtained.

[0248] S3, the photoelectric treated purified water is introduced into the biofilm tank, and after the third aerobic reaction is carried out at 35℃ and dissolved oxygen concentration of 3mg / L for 12 hours, the purified water of the biofilm tank is obtained.

[0249] S4. The purified water from the biofilm tank is returned to the electrolysis tank. Repeat steps S2 to S3 once to obtain purified water that meets the discharge standards.

[0250] The peristaltic pump 4 runs 24 hours a day. By monitoring the COD and ammonia nitrogen values ​​of the influent and effluent in real time, the treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater is evaluated (see Table 1).

[0251] Application Example 2

[0252] This application example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 2, including the following steps:

[0253] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0254] The wastewater to be treated and activated sludge were introduced into the biofilm tank (the mass ratio of wastewater to activated sludge was 4:1), and the aeration device 202 was turned on at 25°C and an aeration rate of 100 m³ / h. 3 After the first aerobic reaction was carried out for 50 hours at a dissolved oxygen concentration of 4 mg / L, a porous biofilm carrier and coconut shell powder were added, and a second aerobic reaction was carried out at 25℃ and a dissolved oxygen concentration of 4 mg / L. (During the second aerobic reaction, the wastewater to be treated was introduced and the treated wastewater was discharged intermittently. During this process, the water level in the biofilm tank remained unchanged. The inlet and outlet of the biofilm tank were opened for 16 hours and closed for 168 hours.) After 8 days, the biofilm thickness of the porous biofilm carrier was 1.9 mm, completing the biofilm growth and biological acclimatization of the porous biofilm carrier. The treated purified water was then discharged.

[0255] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 5 and the conductivity is adjusted to 550μS / cm, the photoelectrocatalytic advanced oxidation system is turned on, and after 60 minutes of photoelectrocatalytic treatment, the photoelectrocatalytic purified effluent is obtained.

[0256] S3. The purified water from the photoelectric treatment is introduced into the biofilm tank and subjected to the third aerobic reaction at 25℃ and dissolved oxygen concentration of 4mg / L for 16 hours to obtain the purified water from the biofilm tank, which is the purified water that meets the discharge standards.

[0257] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0258] Application Example 3

[0259] This application example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 3, including the following steps:

[0260] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0261] The wastewater and activated sludge to be treated are introduced into the biofilm tank, and the aeration device 202 is turned on at 30°C and an aeration rate of 120 m³ / h. 3 After the first aerobic reaction was carried out for 70 hours at a dissolved oxygen concentration of 5 mg / L, a porous biofilm carrier and coconut shell powder were added, and a second aerobic reaction was carried out at 30℃ and a dissolved oxygen concentration of 5 mg / L. (During the second aerobic reaction, the wastewater to be treated was introduced and the treated wastewater was discharged intermittently. During this process, the water level in the biofilm tank remained unchanged. The inlet and outlet of the biofilm tank were opened for 36 hours and closed for 36 hours.) After 9 days, the biofilm thickness of the porous biofilm carrier was 2 mm, completing the biofilm growth and biological acclimatization of the porous biofilm carrier. The treated purified water was then discharged.

[0262] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 6 and the conductivity is adjusted to 750 μS / cm, the photoelectrocatalytic advanced oxidation system is turned on, and after photoelectrocatalytic treatment for 100 min, the photoelectrocatalytic purified effluent is obtained.

[0263] S3. The purified water from the photoelectric treatment is introduced into the biofilm tank and subjected to the third aerobic reaction at 30℃ and dissolved oxygen concentration of 5mg / L for 36 hours to obtain the purified water from the biofilm tank, which is the purified water that meets the discharge standards.

[0264] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0265] Application Example 4

[0266] This application example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Example 4, including the following steps:

[0267] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0268] The wastewater and activated sludge to be treated are introduced into the biofilm tank, and the aeration device 202 is turned on at 20°C and an aeration rate of 150 m³ / h. 3 After the first aerobic reaction was carried out for 90 hours at a dissolved oxygen concentration of 6 mg / L, a porous biofilm carrier and coconut shell powder were added, and a second aerobic reaction was carried out at 20℃ and a dissolved oxygen concentration of 6 mg / L. (During the second aerobic reaction, the wastewater to be treated was introduced and the treated wastewater was discharged intermittently. During this process, the water level in the biofilm tank remained unchanged. The inlet and outlet of the biofilm tank were opened for 40 hours and closed for 48 hours.) After 7 days, the biofilm thickness of the porous biofilm carrier was 1.8 mm, completing the biofilm growth and biological acclimatization of the porous biofilm carrier. The treated purified water was then discharged.

[0269] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 3 and the conductivity is adjusted to 1000 μS / cm, the photoelectrocatalytic advanced oxidation system is turned on, and after photoelectrocatalytic treatment for 120 min, the photoelectrocatalytic purified effluent is obtained.

[0270] S3. The purified water from the photoelectric treatment is introduced into the biofilm tank and subjected to the third aerobic reaction at 20℃ and dissolved oxygen concentration of 6mg / L for 48 hours to obtain the purified water from the biofilm tank, which is the purified water that meets the discharge standards.

[0271] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0272] Application Examples 5-9

[0273] This application example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, similar to Application Example 3, except that the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Examples 5-9 is used respectively. The remaining conditions and steps are the same as in Application Example 3 and will not be repeated.

[0274] Application Comparative Example 1

[0275] This application comparative example provides a wastewater treatment method using a photocatalytic-suspended packing biofilm reactor coupling system, similar to Application Example 3, except that it employs the photocatalytic-suspended packing biofilm reactor coupling system of Comparative Example 1. Specifically, it includes the following steps:

[0276] S1, the same as in application example 3, will not be repeated.

[0277] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 5 and the conductivity is 550μS / cm, the photocatalytic system is turned on, and after photocatalytic treatment for 60 minutes, the photo-treated purified water is obtained.

[0278] S3, the same as application example 3, will not be repeated.

[0279] The treatment effect of the photocatalytic-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0280] Application Comparative Example 2

[0281] This application comparative example provides a wastewater treatment method using an electrocatalytic-suspended packing biofilm reactor coupling system, similar to Application Example 3, except that it employs the electrocatalytic-suspended packing biofilm reactor coupling system of Comparative Example 2. Specifically, it includes the following steps:

[0282] S1, the same as in application example 3, will not be repeated.

[0283] S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 5 and the conductivity is adjusted to 550μS / cm, the electrocatalytic system is turned on, and after 60 minutes of electrocatalytic treatment, the photoelectric purified effluent is obtained.

[0284] S3, the same as application example 3, will not be repeated.

[0285] The treatment effect of the electrocatalytic-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0286] Application Comparative Example 3

[0287] This comparative example provides a wastewater treatment method using a suspended packing biofilm reactor, similar to Application Example 3, except that the suspended packing biofilm reactor of Comparative Example 3 is used. Specifically, it includes the following steps:

[0288] S1, the same as in application example 3, will not be repeated.

[0289] S2, the wastewater to be treated is introduced into the biofilm tank, and after the third aerobic reaction is carried out at 25℃ and dissolved oxygen concentration of 4mg / L for 16 hours, the purified effluent from the biofilm tank is obtained.

[0290] The treatment effect of the suspended packing biofilm reactor on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen levels in the influent and effluent (see Table 1).

[0291] Application Comparative Example 4

[0292] This comparative example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, similar to Application Example 3, except that the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Comparative Example 5 is used, and coconut shell powder is not added in S1. Specifically, it includes the following steps:

[0293] S1, Biofilm growth and biological domestication of porous biofilm carriers:

[0294] The wastewater to be treated and activated sludge were introduced into the biofilm tank (the mass ratio of wastewater to activated sludge was 4:1), and the aeration device 202 was turned on at 25°C and an aeration rate of 100 m³ / h. 3 After the first aerobic reaction was carried out for 50 hours at a dissolved oxygen concentration of 4 mg / L, a porous biofilm carrier was added, and a second aerobic reaction was carried out at 25℃ and a dissolved oxygen concentration of 4 mg / L. (During the second aerobic reaction, the wastewater to be treated was introduced and the treated wastewater was discharged intermittently. During this process, the water level in the biofilm tank remained unchanged. The inlet and outlet of the biofilm tank were opened for 16 hours and closed for 168 hours.) After 8 days, the biofilm thickness of the porous biofilm carrier was 1.6 mm, completing the biofilm growth and biological acclimatization of the porous biofilm carrier. The treated purified water was then discharged.

[0295] S2~S3 are the same as in Application Example 3, and will not be repeated here.

[0296] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0297] Application Comparative Example 5

[0298] This comparative example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, similar to Application Example 3, except that in S2, the pH of the wastewater to be treated is adjusted to 8. The remaining conditions and steps are the same as in Application Example 3 and will not be repeated here.

[0299] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0300] Application Comparative Example 6

[0301] This comparative example provides a wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor, similar to Application Example 3, except that in S2, the conductivity of the wastewater to be treated is adjusted to 200 μS / cm. The remaining conditions and steps are the same as in Application Example 3 and will not be repeated here.

[0302] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupled system on wastewater was evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of influent and effluent (see Table 1).

[0303] Table 1. Influent and effluent performance indicators for application examples and comparative examples.

[0304]

[0305] As shown in Table 1, after the wastewater was treated by the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system of Examples 2-4, the effluent performance indicators of COD, ammonia nitrogen, BOD, SS and color were all better than the national first-class standard, indicating that the photoelectrocatalytic advanced oxidation-suspended packing biofilm reactor coupling system provided by the present invention can effectively treat industrial wastewater at a deep level.

[0306] Compared to Examples 2-4 (Application Examples 2-4), Examples 5-9 (Application Examples 5-9) used non-Bi2O2Fe2O4 semiconductors or non-WSe2 arrays as photoanodes. After wastewater treatment, the effluent performance test results showed a significant increase in COD and ammonia nitrogen levels, with the ammonia nitrogen value exceeding the national Class I standard. This indicates that replacing the Bi2O2Fe2O4 semiconductor nanomaterials or WSe2 arrays in the photoanode reduced the efficiency of its photocatalytic oxidation reaction, failing to leverage the synergistic effect of photocatalysis and electrocatalysis between WSe2 and Bi2O2Fe2O4, resulting in a significant decrease in the overall water treatment performance compared to Examples 1-4. This invention uses a composite of nano-WSe2 and Bi2O2Fe2O4 semiconductors, which can fully utilize the synergistic effect of the composite photoanode and cathode. Under illumination and an applied electric field, a large number of electrons and holes are generated. After separation, the electrons and holes move directionally, accumulating at the anode and cathode and generating a large number of active free radicals. These active free radicals react with pollutants in the water, significantly improving the water purification efficiency.

[0307] Compared to Example 3 (Application Example 3), Comparative Example 1 (Application Comparative Example 1) only provided a photocatalytic system. After wastewater treatment, the effluent performance test results showed a significant increase in COD and ammonia nitrogen levels, exceeding the national Class I standard. This indicates that the application of electricity affected the water treatment capacity of the photoelectrocatalytic advanced oxidation system. Under light-only conditions, some of the electrons and holes generated by the photoanode were not separated and moved in a timely manner, leading to recombination of electrons and holes. This weakened the photocurrent and hole density, resulting in a decrease in photoelectric conversion efficiency. The oxidation-reduction performance of the advanced oxidation reaction system could not exert its original synergistic effect, thus leading to a significant decrease in the water treatment effect of the coupled system and a significant increase in the effluent COD value.

[0308] Compared to Example 3 (Application Example 3), Comparative Example 2 (Application Comparative Example 2) only provided an electrocatalytic system. After wastewater treatment, the effluent performance test results showed a significant decrease in COD, but a substantial increase in ammonia nitrogen, both exceeding the national Class I standard. This indicates that the effect of single electrochemical treatment is not ideal. The photoanode can only generate electrons and holes and improve photoelectric conversion efficiency when excited by light. Electrocatalytic treatment with only an electric field effect cannot fully utilize the synergistic effect of photocatalytic and electrocatalytic reactions between the Bi2O2Fe2O4 semiconductor and the WSe2 array, resulting in a decrease in the water treatment effect of the coupled system and a significant increase in the effluent ammonia nitrogen value.

[0309] Compared to Example 3 (Application Example 3), Comparative Example 3 (Application Comparative Example 3) only contained a suspended packing biofilm reactor. After wastewater treatment, the effluent performance test results showed a significant increase in both COD and ammonia nitrogen values. This indicates that a single suspended packing biofilm reactor cannot simultaneously achieve both efficiency and biodegradability in wastewater treatment using photoelectrocatalytic advanced oxidation. The lack of synergistic complementarity with the photoelectrocatalytic system negatively impacts the purification effect. Comparative Example 4 only contained a photoelectrocatalytic advanced oxidation system. After wastewater treatment, the performance test results of the photoelectrocatalytic purified effluent and the biofilm tank purified effluent from Application Example 3 showed weak treatment efficiency for COD, BOD, and ammonia nitrogen, especially a significant increase in ammonia nitrogen values. This indicates that single photoelectrocatalytic advanced oxidation wastewater treatment lacks the microbial decomposition effect of MBBR on organic pollutants in wastewater, particularly the nitrification and denitrification of ammonia nitrogen. The purification efficiency is significantly negatively affected, and the single photoelectrocatalytic advanced oxidation system cannot simultaneously meet the requirements for energy consumption control and recycling. The wastewater treatment effect is also significantly lower than that of the coupled system, and the effluent parameters do not meet the national Class I standard.

[0310] Compared to Example 3 (Application Example 3), the MBBR in Comparative Example 5 (Application Comparative Example 4) did not contain coconut shell powder. After wastewater treatment, the effluent performance test results showed that the treatment efficiency for COD, BOD, and ammonia nitrogen was lower than expected, with significant increases in these values, especially in wastewater color. This indicates that adding coconut shell powder to the activated sludge of the MBBR can significantly improve the wastewater treatment capacity of the coupled system; without coconut shell powder, the deep wastewater treatment effect cannot be achieved.

[0311] Compared to Application Example 3, Comparative Examples 5 and 6 altered the pH and conductivity of the wastewater to be treated in the photoelectrocatalytic advanced oxidation system. After wastewater treatment, the effluent performance test results showed that none of the effluent indicators met national standards. This indicates that pH and conductivity, among the operating parameters, have a significant impact on the water treatment efficiency of the coupled process system.

[0312] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system, characterized in that, include: Photoelectrocatalytic advanced oxidation system and suspended packed biofilm reactor; The photoelectrocatalytic advanced oxidation system includes a photoanode, a photocathode, an electrolytic cell, a power source, and a light source; The photoanode and the photocathode are located in the electrolytic cell, and the photoanode and the photocathode are respectively connected to the power source via wires; The light source is located outside the electrolytic cell and is used to irradiate the electrolytic cell with light. The photoanode includes an anode substrate and a photoanode material loaded on the anode substrate; The photoanode material comprises a WSe2 array layer and a Bi2O2Fe2O4 layer loaded on the WSe2 array layer, wherein the Bi2O2Fe2O4 layer further comprises carbon nanofibers; the diameter of the carbon nanofibers is 150nm~200nm and the length is 5μm~20μm; the mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofibers in the photoanode material is 200:(10~50):(0.8~1.6); The suspended packing biofilm reactor includes a biofilm tank, an aeration device, activated sludge, a porous biofilm carrier, and coconut shell powder. The aeration device is located below the biofilm tank and is used to create an aerobic environment; the activated sludge, porous biofilm carrier and coconut shell powder are located in the biofilm tank; The inlet of the biofilm tank is connected to the outlet of the electrolysis tank, and the outlet of the biofilm tank is connected to the inlet of the electrolysis tank, for recirculation and multiple cycles of treatment.

2. The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system as described in claim 1, characterized in that, The thickness of the WSe2 array layer is 3μm~5μm, and the thickness of the Bi2O2Fe2O4 layer is 80nm~200nm.

3. The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system as described in claim 1, characterized in that, The preparation method of Bi2O2Fe2O4 includes the following steps: Fe2O4 2- Salt, bismuth salt, emulsifier, ammonium acetate solution and acid regulator are added to water and hydrolyzed under acidic conditions to obtain a suspension; the pH of the suspension is then adjusted to weakly alkaline, and a first hydrothermal reaction is carried out to obtain Bi2O2Fe2O4. The method for preparing the photoanode includes the following steps: Sa, the anode substrate is immersed in a mixture of WSe2 and water to carry out a second hydrothermal reaction to obtain the primary electrode; Sb, the primary electrode is immersed in a mixture of WSe2, silane coupling agent and cosolvent, and a third hydrothermal reaction is carried out to form a WSe2 array layer, thus obtaining a WSe2 array electrode; Sc, a mixture of Bi2O2Fe2O4, binder and co-solvent is coated onto the WSe2 array electrode, and then calcined to form a Bi2O2Fe2O4 layer, thus obtaining a photoanode.

4. The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system as described in claim 3, characterized in that, The Fe2O4 2- The salt includes sodium ferrate, the bismuth salt includes bismuth nitrate, the emulsifier includes polyvinyl alcohol, the concentration of the ammonium acetate solution is 1.7M~2.3M, and the acidity adjuster includes a 1.7M~2.3M acetic acid solution; and / or The Fe2O4 2- The mass ratio of salt, bismuth salt, emulsifier, ammonium acetate solution, and water is (2~8):(4~16):(0.5~1):(0.02~0.5):(100~160), the acidic condition is pH=3~5, and the pH of the suspension is adjusted to 7~8 using urea; and / or The hydrolysis reaction is carried out at a temperature of 20℃~30℃ for a reaction time of 30min~50min; and / or The temperature of the first hydrothermal reaction is 180℃~220℃, and the reaction time is 8h~10h; and / or In Sa, the mass ratio of WSe2 to water is (1~4):(80~100); and / or In Sa, the temperature of the second hydrothermal reaction is 100℃~120℃, and the reaction time is 25min~40min; and / or In Sb and Sc, the co-solvent comprises 40wt% to 60wt% of a povidone aqueous solution; and / or In Sb, the mass ratio of WSe2, silane coupling agent, and cosolvent is (2~5):(1~4):(10~20); and / or In Sb, the temperature of the third hydrothermal reaction is 80℃~120℃, and the reaction time is 4h~8h; and / or In Sc, the mixture further includes carbon nanofibers; and / or In Sc, the adhesive comprises polyethylene dioxythiophene; and / or In Sc, the mass ratio of Bi2O2Fe2O4, binder, and co-solvent is (6~32):(1~8):(10~80); and / or In Sc, the calcination temperature is 160℃~260℃, and the calcination time is 80min~120min.

5. The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system as described in claim 1, characterized in that, The amount of the porous biofilm carrier added is 3.5 g / L to 20 g / L, the amount of the activated sludge added is 0.1 kg / L to 0.6 kg / L, and the amount of coconut shell powder added is 0.1 g / L to 0.4 g / L.

6. The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system as described in claim 1, characterized in that, A water storage device is also connected between the photoelectrocatalytic advanced oxidation system and the suspended packing biofilm reactor. The inlet of the water storage device is connected to the outlet of the electrolysis cell, and the outlet of the water storage device is connected to the inlet of the biofilm tank. A peristaltic pump is connected between the outlet of the electrolytic cell and the inlet of the water storage device, a peristaltic pump is connected between the outlet of the water storage device and the inlet of the biofilm tank, and a peristaltic pump is connected between the outlet of the biofilm tank and the inlet of the electrolytic cell, respectively, to control the inlet and outlet flow rates.

7. A wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor, characterized in that, The photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor coupling system according to any one of claims 1 to 6 includes the following steps: S1, Biofilm growth and biological domestication of porous biofilm carriers: The wastewater to be treated and activated sludge are introduced into the biofilm tank for the first aerobic reaction; then porous biofilm carrier and coconut shell powder are added, and the wastewater to be treated and the treated wastewater are intermittently introduced for the second aerobic reaction. After 5 to 10 days, the treated purified water is discharged. S2, the wastewater to be treated is introduced into the electrolytic cell, the pH of the wastewater to be treated is adjusted to 2~7 and the conductivity is adjusted to 250μS / cm~1000μS / cm, the photoelectrocatalytic advanced oxidation system is turned on to carry out photoelectrocatalytic treatment, and the photoelectrocatalytic purified effluent is obtained; S3, the photoelectric treated purified water is introduced into the biofilm tank to carry out the third aerobic reaction, and the purified water of the biofilm tank is obtained. S4, the purified water from the biofilm tank is returned to the electrolysis tank, and the operation of steps S2 to S3 is repeated until purified water that meets the discharge standards is obtained.

8. The wastewater treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended packed biofilm reactor as described in claim 7, characterized in that, In S1, the temperature of the first aerobic reaction is 20℃~35℃, and the ventilation rate is 100m³ / h. 3 / h~150m 3 / h, for a time period of 30h~90h; and / or In S1, the temperature of the second aerobic reaction is 20℃~35℃, the dissolved oxygen concentration is 3mg / L~6mg / L, and the time is 7d~9d; and / or In S1, after the second aerobic reaction is completed, the biofilm thickness of the porous biofilm carrier is 1.8 mm to 2 mm; and / or In S1~S2, the wastewater to be treated has a COD of 150 mg / L~12000 mg / L, an ammonia nitrogen value of 50 mg / L~390 mg / L, a BOD of 70 mg / L~410 mg / L, a suspended solids content of 100 mg / L~190 mg / L, and a heavy metal ion content of 10 mg / L~180 mg / L; and / or In S2, the photoelectrocatalytic treatment time is 30 min to 120 min; and / or In S3, the temperature of the third aerobic treatment is 20℃~35℃, the dissolved oxygen concentration is 3mg / L~6mg / L, and the time is 12h~48h.

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