Photoelectrocatalysis advanced oxidation-suspended filler bio-membrane reactor coupling system and sewage treatment method

Abstract

The invention relates to the technical field of sewage treatment, and particularly discloses a photoelectrocatalysis advanced oxidation-suspended filler bio-membrane reactor coupling system and a sewage treatment method. The coupling system comprises a photoelectrocatalysis advanced oxidation system and a suspended filler bio-membrane reactor; the photoelectrocatalysis advanced oxidation system comprises a photoanode, a photocathode, an electrolytic tank, a power supply and a light source; the suspended filler bio-membrane reactor comprises a bio-membrane tank, an aeration device, activated sludge, a porous bio-membrane carrier and coconut shell powder. By coordinating the operation mode of the coupling system, adopting the mode that the photoelectrocatalysis advanced oxidation system is in front of the MBBR and adding the advantages of adsorption, decoloration and microorganism growth and metabolism promotion of the coconut shell powder, the treatment efficiency of pollutants in water can be improved, the photoelectrocatalysis advanced oxidation time can be shortened, and reasonable utilization of energy is achieved. The coupling system also has the characteristics of environmental friendliness, simplicity in operation and suitability for various water bodies.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a photoelectric catalytic advanced oxidation-suspended filler biofilm reactor coupling system and a sewage treatment method. Background Art

[0002] Industrial wastewater has the characteristics of complex composition, difficult degradation, and large fluctuations in water quality and quantity. Industrial wastewater contains various organic and inorganic pollutants. For example, printing and dyeing wastewater contains a large amount of dyes and additives (such as alkali sulfide, hydrosulfite, etc.). These organic substances have complex components and diverse structures. Some of them are also biologically toxic, and it is difficult to completely remove them through a single treatment method; electroplating wastewater is rich in heavy metal ions, such as chromium, nickel, cadmium, copper, etc. These heavy metals cannot be biodegraded, will exist in the environment for a long time, and are easily enriched in organisms, causing serious harm to the ecosystem and human health. Different heavy metals require different treatment processes to be effectively removed, which increases the complexity of treatment.

[0003] At present, the common methods for treating industrial wastewater include physical methods, chemical methods, biological methods and their corresponding combined methods. The number of catalyst cycles in the physical method is limited, and the traditional biochemical method has many disadvantages such as large footprint, long treatment cycle, and poor treatment effect. Photoelectrocatalytic advanced oxidation sewage treatment technology is that under the combined action of light and external electric field, the photoelectrocatalytic material is excited to produce a large number of electrons and holes. After the separation of electrons and holes, they move in a directional manner, gather at the positive and negative poles and produce a large number of active free radicals. These active free radicals with strong oxidizing properties can react with pollutants in the water and be mineralized into carbon dioxide, water and inorganic salts, thereby achieving the purpose of water purification. In addition, these active free radicals can purify different types of water bodies, and can also enhance the biodegradability of the treated water body, thereby reducing the difficulty of its deep treatment. The suspended filler biofilm reactor (MBBR) is a sewage treatment device that combines the traditional activated sludge method with the biofilm method. MBBR uses suspended fillers as a carrier for biofilm attachment and uses microorganisms to consume nutrients in the water to achieve the purpose of purifying water quality. Compared with other biofilm treatment processes, MBBR has more advantages in denitrification, resistance to shock loads and floor space, but its treatment effect on sewage with strong biological toxicity or poor biodegradability is poor.

[0004] Due to the complex composition of industrial wastewater, a single treatment process often cannot meet the requirements of standard discharge, and a combination of multiple treatment processes is usually required. However, how to reasonably select and optimize these combined processes so that they work together to achieve the best treatment effect is a difficulty in industrial wastewater treatment. Therefore, it is urgent to develop a wastewater treatment coupling system to improve the inability of existing technologies to deeply treat complex water bodies. Summary of the invention

[0005] In view of the above problems, the present invention provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system and a sewage treatment method. By coupling the photocatalytic oxidation technology, the electrocatalytic reaction technology and the biofilm reactor, the synergistic effect of each part is brought into play, and the deep treatment efficiency of complex water bodies is improved. It has the characteristics of simple operation, long-term stable operation, mild reaction conditions, small footprint, and obvious sewage purification efficiency.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: In a first aspect, the present invention provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, comprising: a photoelectrocatalytic advanced oxidation system and a suspended filler biofilm reactor; The photoelectrocatalytic advanced oxidation system comprises 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 supply through wires; the light source is located outside the electrolytic cell and is used to irradiate the electrolytic cell with light; The suspended filler biofilm reactor comprises a biofilm tank, an aeration device, activated sludge, a porous biofilm carrier and coconut shell powder; The aeration device is located below the biofilm pool and is used to create an aerobic environment; the activated sludge, porous biofilm carrier and coconut shell powder are located in the biofilm pool; The water inlet of the biofilm pool is connected to the water outlet of the electrolytic cell, and the water outlet of the biofilm pool is connected to the water inlet of the electrolytic cell for reflux and multiple circulation treatments.

[0007] Compared with the prior art, the electrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system (referred to as the coupling system) provided by the present invention has obvious sewage treatment efficiency of the photoelectrocatalytic advanced oxidation system, has the characteristics of high energy consumption and limited catalyst cycle times, and is more suitable for short-term multiple operations, while MBBR has the characteristics of long-term stable operation and strong resistance to shock loads. The present invention fully utilizes the advantages of the electrocatalytic advanced oxidation system and MBBR by coupling the electrocatalytic advanced oxidation system with the MBBR, which not only improves the photoelectrocatalytic treatment capacity of complex water bodies, but also enhances the deep treatment efficiency of MBBR for industrial sewage; while improving the treatment efficiency, the coupling system can also take into account the rational use of energy, and while reducing the toxicity of the water body, it can also improve its biodegradability. The two sewage treatment systems complement each other, can meet the needs of deep treatment of industrial sewage, and have high market application value.

[0008] The present invention coordinates the operation mode of the coupling system, adopts the mode of photoelectrocatalytic advanced oxidation system in front and MBBR in the back, and takes advantage of coconut shell powder adsorption, decolorization, and promotion of microbial growth metabolism, which can not only improve the treatment efficiency of pollutants in water, but also shorten the time of photoelectrocatalytic advanced oxidation and realize the rational use of energy. The coupling system is also environmentally friendly, easy to operate, and suitable for various water bodies. The present invention connects the water outlet of the biofilm pool with the water inlet of the electrolytic cell, which can realize the repeated treatment of stubborn substances in complex water bodies.

[0009] Through a large number of experiments, the present invention found that the microporous structure of coconut shell powder has an adsorption and fixation effect on nutrient sources, and is compounded with porous biofilm carriers to promote the growth and metabolism of microorganisms, accelerate the growth and film formation of microorganisms on activated sludge and porous biofilm carriers, and greatly improve the activity of microorganisms. At the same time, coconut shell powder has an adsorption and decolorization effect on metal ions and toxic pollutants, thereby increasing the purification and cleaning efficiency of pollutants.

[0010] The advantages of the present invention lie in its long-term stable operation, mild reaction conditions, green and low-carbon nature, strong water treatment effect, and the ability to overcome the defects of high energy consumption and limited catalyst cycles in advanced oxidation technology, and solve the problem of large footprint and long treatment cycle in biotechnology. Through the coupling of the photoelectric catalytic advanced oxidation system with MBBR and the synergistic effect of its various components, materials, and biofilm structures, a deep treatment effect of sewage is achieved.

[0011] Preferably, the photoanode comprises an anode substrate and a photoanode material loaded on the anode substrate; The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4-containing layer supported on the WSe2 array layer.

[0012] The photoanode material provided by the present invention uses nano WSe2 and Bi2O2Fe2O4 semiconductor composite materials as the photoelectrocatalytic material of the photoanode, and uses the photoelectrocatalytic ability to remove pollutants in sewage. The photoelectrocatalytic material WSe2 has a narrow band gap (about 1.65eV), good light absorption performance and photoelectric storage capacity, and has excellent catalytic degradation effect on pollutants; through doping modification, it can obtain n-type or p-type semiconductor characteristics, sensitize other semiconductors with wider band gaps to form sensitized nanocomposite materials, reduce the band gap width, and improve the photoelectric conversion efficiency, thereby producing excellent photoelectrocatalytic activity, improving the utilization rate of visible light, increasing the generation of photogenerated electrons, and improving the separation and transmission rate of photogenerated electrons and the photoelectric conversion efficiency, thereby improving the sewage treatment effect. Bismuth metal semiconductors have low toxicity, high electrical conductivity and an adjustable suitable band gap, and have excellent photoelectrocatalytic reaction activity and photoelectric conversion efficiency. [Bi2O2] 2+ Layer and salt acid radical [Fe2O4]2- The stacked structure of the Aurvillius photocatalytic material Bi2O2Fe2O4, [Bi2O2] 2+ Layer and anion [Fe2O4] 2- The layers are vertically alternating, and this structure is more conducive to promoting the separation of photogenerated electrons and holes, thereby improving the catalytic oxidation reaction activity of the electrode. The present invention selects a new type of Bi2O2Fe2O4 and WSe2 to form a sensitized nanocomposite, which can improve their respective sunlight response capabilities and photoelectrocatalytic performance, and has obvious application advantages in the fields of environmental engineering and sewage treatment.

[0013] The photoanode provided by the present invention improves the deep treatment efficiency of complex water bodies of industrial sewage by loading the photoanode material (including WSe2 array layer and Bi2O2Fe2O4 layer) on the anode substrate. The present invention adopts non-toxic, low-cost, acid-base corrosion-resistant nano-metal WSe2 array and Bi2O2Fe2O4 semiconductor composite electrode. The electrode material has high adhesion and is not easy to fall off. It can be taken off for cleaning, soaking, regeneration and reuse, solving the problems of traditional suspended photocatalysts being difficult to recycle and easy to fall off.

[0014] Further preferably, the anode substrate comprises at least one of stainless steel mesh, titanium mesh, copper mesh, aluminum mesh, molybdenum mesh, nickel mesh, stainless steel sheet, nickel foam, titanium foam or aluminum foam.

[0015] In the present invention, the anode substrate is made of metal material, and the base shape is sheet, mesh or foam mesh. It has a unique porous structure, stable physical and chemical properties and good conductivity, and is stable in different electrolytes. The porous structure can not only increase the surface area of ​​the anode, but also facilitate the reaction between ions in the electrolyte and the active materials on the electrode, thereby improving the activity of the photoelectrocatalytic reaction, which is beneficial to the improvement of the sewage treatment effect of the photoelectrocatalytic advanced oxidation system.

[0016] Further preferably, the anode substrate has a length of 50 mm to 100 mm, a width of 200 mm to 400 mm, and a thickness of 3 mm to 5 mm.

[0017] The present invention utilizes a cheap anode substrate with a large specific surface area and stable physical and chemical properties as a loading substrate for the photoelectric catalyst, effectively utilizes the photoelectric catalytic synergistic effect, and saves sewage treatment costs.

[0018] Further preferably, the thickness of the WSe2 array layer is 3 μm~5 μm.

[0019] It should be noted that the WSe2 array layer in the present invention is arranged by a single layer of WSe2 array, and the thickness of the WSe2 array layer is the length of the WSe2 array.

[0020] Further preferably, the thickness of the Bi2O2Fe2O4-containing layer is 80nm~200nm.

[0021] Further preferably, the Bi2O2Fe2O4-containing layer also includes carbon nanofibers.

[0022] Carbon nanofibers have excellent toughness, mechanical strength, adhesion and conductivity. They can increase the adhesion between the active substances (WSe2 array and Bi2O2Fe2O4) in the photoanode material and the anode matrix, prevent the active substances from falling off the anode matrix, and improve the stability of the photoelectrode. At the same time, carbon nanofibers have good conductivity and will not reduce the electron transport performance of the photoanode, which is beneficial to improving the photoelectric catalytic activity of the electrode.

[0023] More preferably, the carbon nanofibers have a diameter of 150 nm to 200 nm and a length of 5 μm to 20 μm.

[0024] Further preferably, the mass ratio of WSe2 to Bi2O2Fe2O4 in the photoanode material is 200:(10~50).

[0025] More preferably, the mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofibers in the photoanode material is 200:(10~50):(0.8~1.6), more preferably 200:(20~40):(1~1.4).

[0026] By limiting the thickness of the WSe2 array layer and the Bi2O2Fe2O4-containing layer and the amount of WSe2 and Bi2O2Fe2O4 used, the present invention can better exert the synergistic effect of the two, and has both good light response ability and good electrocatalytic performance.

[0027] More preferably, the WSe2 has n-type semiconductor characteristics and a particle size of 10nm~200nm.

[0028] More preferably, the preparation method of Bi2O2Fe2O4 comprises the following steps: Fe2O4 2- Salt, bismuth salt, emulsifier, ammonium acetate solution and acidic regulator are added to water, and a hydrolysis reaction is carried out under acidic conditions to effectively avoid the generation of a large amount of non-hydrolysis products (such as ferric oxyhydroxide, ferrous hydroxide, etc.) to obtain a suspension; after adjusting the pH of the suspension to be weakly alkaline, a first hydrothermal reaction is carried out to obtain Bi2O2Fe2O4.

[0029] In the present invention, Fe2O4 2-Salt and bismuth salt form Bi(OH)Fe2O4 white suspension through hydrolysis reaction in ammonium acetate and acidic conditions, and the emulsifier can effectively reduce the number of agglomerated particles; then, through the first hydrothermal reaction under weak alkaline conditions, the axial layer lattice is continuously replaced and overlapped, and the bismuth salt and Bi(OH)Fe2O4 continue to react, finally generating nano-scale Bi2O2Fe2O4.

[0030] More preferably, the Fe2O4 2- Salts include sodium ferrite.

[0031] More preferably, the bismuth salt comprises bismuth nitrate.

[0032] More preferably, the emulsifier comprises polyvinyl alcohol.

[0033] More preferably, the concentration of the ammonium acetate solution is 1.7M~2.3M.

[0034] More preferably, the acidic regulator comprises a 1.7M to 2.3M acetic acid solution.

[0035] 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).

[0036] More preferably, the acidic condition is pH=3~5.

[0037] More preferably, the temperature of the hydrolysis reaction is 20°C to 30°C, and the reaction time is 30min to 50min.

[0038] More preferably, urea is used to adjust the pH of the suspension to 7-8.

[0039] More preferably, the temperature of the first hydrothermal reaction is 180° C. to 220° C., and the reaction time is 8 h to 10 h.

[0040] For example, after the first hydrothermal reaction is completed, the process further includes: cooling to room temperature, solid-liquid separation, washing and drying the solid to obtain Bi2O2Fe2O4.

[0041] More preferably, the particle size of the Bi2O2Fe2O4 is 10nm~150nm.

[0042] Preferably, the method for preparing the photoanode comprises the following steps: Sa, immersing the anode substrate in a mixture of WSe2 and water to perform a second hydrothermal reaction to obtain a primary electrode; Sb, immersing the primary electrode in a mixed solution of WSe2, a silane coupling agent and a co-solvent, performing a third hydrothermal reaction to form a WSe2 array layer, thereby obtaining a WSe2 array electrode; Sc, coating a mixed solution of Bi2O2Fe2O4, an adhesive and a solvent on the WSe2 array electrode, and then calcining to form a Bi2O2Fe2O4 layer to obtain a photoanode.

[0043] The preparation method of the photoanode provided by the present invention adopts the sol-gel method to load and grow the photoanode material on the anode substrate, and the photoanode is prepared by calcining and utilizing the annealing characteristics. The present invention first utilizes the second hydrothermal reaction to form a primary electrode; then, under the action of a cosolvent, the hydrothermal effect is utilized to allow nano WSe2 to enter the surface of the primary electrode, and continuously nucleate and diffuse, and adsorb and couple under the action of a silane coupling agent, and deposit to form a WSe2 array layer to obtain a WSe2 array electrode; finally, the sol-gel method is used again to coat Bi2O2Fe2O4 on the surface of the WSe2 array electrode, and calcined to form a Bi2O2Fe2O4-containing layer to obtain a photoanode.

[0044] For example, in Sa, before the immersion, the method further includes: placing the anode substrate in acetone and water in sequence, ultrasonicating for 10 minutes to 15 minutes respectively, and then drying.

[0045] The present invention pre-treats the anode substrate first, which can effectively remove impurities and oil stains on the surface of the anode substrate and increase the adhesion of subsequent photoelectric catalytic materials on the surface of the electrode substrate.

[0046] Further preferably, in Sa, the mass ratio of WSe2 to water is (1~4):(80~100).

[0047] Further preferably, in Sa, the immersion time is 30 min to 60 min.

[0048] Further preferably, in Sa, the temperature of the second hydrothermal reaction is 100° C. to 120° C., and the reaction time is 25 min to 40 min.

[0049] Under the specific second hydrothermal reaction conditions, the present invention enables WSe2 to be evenly diffused and distributed on the surface of the anode substrate while ensuring that the crystal form of WSe2 remains unchanged, while improving the cohesiveness and adhesion of WSe2 on the anode substrate.

[0050] Further preferably, in Sb, the silane coupling agent includes KH560.

[0051] Further preferably, in Sb and Sc, the co-solvent comprises 40 wt % to 60 wt % of a polyvidone aqueous solution.

[0052] The polyvidone aqueous solution is an ionic liquid, which can increase the solubility of the system, reduce the interfacial tension, and is conducive to the full progress of the third hydrothermal reaction.

[0053] Further preferably, in Sb, the mass ratio of WSe2, silane coupling agent and co-solvent is (2~5):(1~4):(10~20).

[0054] Further preferably, in Sb, the temperature of the third hydrothermal reaction is 80° C. to 120° C., and the reaction time is 4 h to 8 h.

[0055] It should be noted that the present invention does not limit the amount of the photoanode and the mixed liquid in Sa, as long as the mixed liquid can immerse the anode substrate; the present invention does not limit the amount of the primary electrode and the mixed liquid in Sb, as long as the mixed liquid can immerse the primary electrode.

[0056] Further preferably, in Sc, the mixed liquid also includes carbon nanofibers.

[0057] Further preferably, in Sc, the adhesive comprises polyethylene dioxythiophene.

[0058] Polyethylene dioxythiophene (PEDOT) is an electrode material adhesive with electronic conductivity. It is used in the present invention to improve the bonding effect of Bi2O2Fe2O4 and carbon nanofibers on the WSe2 array electrode.

[0059] Further preferably, in Sc, the mass ratio of Bi2O2Fe2O4, adhesive and solvent is (6~32):(1~8):(10~80), further preferably (10~28):(2~7):(25~65), and more preferably (15~22):(3~6):(30~50).

[0060] Further preferably, in Sc, the coating thickness is 80nm~200nm.

[0061] For example, in Sc, after coating and before calcining, the process further includes: natural drying for 4 min to 10 min.

[0062] More preferably, in Sc, the calcination temperature is 160° C. to 260° C. (more preferably 180° C. to 240° C.), and the calcination time is 80 min to 120 min.

[0063] In the present invention, under specific calcination conditions, the Bi2O2Fe2O4-containing layer solidifies, the Bi2O2Fe2O4 lattice gradually diffuses and tends to equilibrium, thereby increasing the cohesiveness and adhesion of the Bi2O2Fe2O4-containing layer on the WSe2 array electrode.

[0064] In the exemplary embodiment, Sc, after calcination, the step further comprises: cooling to room temperature.

[0065] Preferably, the photocathode includes at least one of a graphite electrode, a carbon rod electrode, a graphite fiber felt electrode or a plated metal electrode.

[0066] Further preferably, the photocathode includes at least one of carbon cloth, carbon fiber felt, titanium sheet, titanium mesh, platinum sheet or platinum mesh.

[0067] Preferably, the photoanode and the photocathode have the same size.

[0068] The present invention selects a sheet-shaped or mesh-shaped corrosion-resistant electrode as the photocathode, which has a small overpotential, a high hydrogen evolution potential, and is not prone to generating hydrogen and hydrogen embrittlement. The preferred photocathode of the present invention can fully utilize energy, reduce power consumption, and has the advantage of low carbon emission reduction.

[0069] Preferably, the volume of the electrolytic cell is 20L~150L.

[0070] Preferably, a stirring device is provided in the electrolytic cell.

[0071] The stirring device can make the photoelectrocatalytic advanced oxidation reaction proceed more fully.

[0072] For example, the light source adopts a sunlight simulation system.

[0073] Preferably, the power supply is a DC power supply of 80V~220V.

[0074] In the present invention, the current of the DC regulated power supply can be set according to a linear function with time as a variable, thereby reducing degradation energy consumption and improving the current efficiency of the photoelectrocatalytic advanced oxidation system.

[0075] Preferably, the volume of the biofilm pool is 250L~600L.

[0076] Preferably, a stirring device is provided in the biofilm pool.

[0077] For example, the material of the biofilm pool includes at least one of metal, enamel, plexiglass, plastic or acrylic.

[0078] Preferably, the upper side wall of the biofilm pool is provided with a gas outlet for discharging gas.

[0079] Preferably, the porous biofilm carrier includes at least one of polyurethane sponge, polyurethane hydrogel, polypropylene filler or polyethylene filler.

[0080] Preferably, the porous biofilm carrier has a pore size of 300 nm to 600 nm and a specific gravity of 0.8 g / cm 3 ~0.85g / cm 3 , surface area is 1100mm 2 / g~1375mm 2 / g.

[0081] The preferred biofilm carrier of the present invention has a porous and transparent structure with an increased specific surface area, making it easier for microorganisms to attach and thus form a dense biofilm.

[0082] For example, the porous biofilm carrier needs to be pretreated before use, including the following steps: The porous biofilm carrier is sequentially immersed in an alkaline solution and an acid solution for cleaning.

[0083] For example, the size of the porous biofilm carrier is (5-20) mm×(5-20) mm×(5-20) mm, such as 5 mm×5 mm×5 mm, 10 mm×10 mm×10 mm, 15 mm×15 mm×15 mm or 20 mm×20 mm×20 mm.

[0084] 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 % nitric acid aqueous solution.

[0085] For example, the immersion time of the alkaline solution is 1h~2h, and the immersion time of the alkaline solution is 1h~2h.

[0086] For example, the cleaning may be ultrasonic cleaning, and after cleaning, the pH of the porous biofilm carrier is 6-7 (more preferably 6-6.5). Cleaning to near neutrality is conducive to subsequent microorganisms attaching to the porous biofilm carrier for growth and development, thereby forming a biofilm.

[0087] The purpose of using alkali washing and acid washing in the present invention is to remove impurities inside the porous biofilm carrier, such as grease particles, organic and inorganic substances, ash, etc. The present invention does not specifically limit the amount of acid solution and alkali solution used, as long as the porous biofilm carrier can be immersed.

[0088] Preferably, the added amount of the porous biofilm carrier is 3.5 g / L to 20 g / L, and more preferably 5 g / L to 15 g / L.

[0089] 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.

[0090] Preferably, the particle size of the coconut shell powder is 450 mesh to 600 mesh.

[0091] Preferably, the added amount of the coconut shell powder is 0.1 g / L to 0.4 g / L.

[0092] Preferably, a water storage device is also connected between the photoelectrocatalytic advanced oxidation system and the suspended filler biofilm reactor; The water inlet of the water storage device is connected to the water outlet of the electrolytic cell, and the water outlet of the water storage device is connected to the water inlet of the biofilm pool.

[0093] In view of the different inlet and outlet water control and effective volume differences of the photoelectrocatalytic advanced oxidation system and MBBR, the present invention adds a water storage device between the two for buffering, thereby realizing the simultaneous operation of the photoelectrocatalytic advanced oxidation system and MBBR, formulating sewage treatment solutions according to different water bodies, adjusting the start-up time and power of the water pump operation in different links, and enabling the peristaltic water pump to operate all day, thereby greatly improving the efficiency of sewage treatment.

[0094] Preferably, a peristaltic water pump is connected between the water outlet of the electrolytic cell and the water inlet of the biofilm pool, and a peristaltic water pump is connected between the water outlet of the biofilm pool and the water inlet of the electrolytic cell, which are used to control the water inlet flow rate and the water outlet flow rate, respectively.

[0095] Further preferably, a peristaltic water pump is connected between the water outlet of the electrolytic cell and the water inlet of the water storage device, and a peristaltic water pump is connected between the water outlet of the water storage device and the water inlet of the biofilm tank.

[0096] The present invention can control the water inlet flow rate and the water outlet flow rate through a peristaltic water pump, thereby adjusting the treatment efficiency of pollutants in the water, shortening the time of photoelectrocatalytic advanced oxidation and biofilm treatment, and realizing the rational use of energy.

[0097] In a second aspect, the present invention provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, comprising the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The sewage to be treated and the activated sludge are introduced into the biofilm tank to carry out the first aerobic reaction; then the porous biofilm carrier and coconut shell powder are added, and the sewage to be treated and the treated sewage are intermittently introduced to carry out the second aerobic reaction. After 5 to 10 days, the treated purified water is discharged; S2, introducing the wastewater to be treated into the electrolytic cell, adjusting the pH value of the wastewater to be treated to 2-7 and the conductivity to 250 μS / cm-1000 μS / cm, starting the photoelectrocatalytic advanced oxidation system, and performing photoelectrocatalytic treatment to obtain photoelectrocatalytic purified effluent; S3, introducing the photoelectric treatment purified water into a biofilm pool to perform a third aerobic reaction to obtain biofilm pool purified water; S4, returning the purified water from the biofilm pool to the electrolytic cell, and repeating steps S2 to S3 until purified water that meets discharge standards is obtained.

[0098] The sewage treatment method coupled with the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor provided by the present invention comprises the following steps: in the MBBR microbial culturing and domestication stage, nano coconut shell powder is added to the activated sludge, and the adsorption and fixation of nutrient sources by the microporous structure are utilized to promote the growth and metabolism of microorganisms on the activated sludge and porous biofilm carriers, thereby accelerating the growth and film formation of microorganisms; through the photoelectrocatalytic treatment, not only the complex organic matter in the water body is decomposed and treated, but also the biodegradability of the water body is improved, and the subsequent MBBR deep treatment of sewage is effectively enhanced; combined with the adsorption effect of coconut shell powder on metal ions and toxic pollutants, the purification and cleaning efficiency of pollutants in the water body is increased; finally, through the terminal reflux operation, the stubborn substances in the water body can be repeatedly treated until the discharge meets the standards.

[0099] The sewage treatment method coupled with photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor provided by the present invention has mild reaction conditions and is green and low-carbon, overcomes the defects of traditional advanced oxidation technology such as high energy consumption and limited catalyst cycle times, and greatly shortens the treatment cycle.

[0100] Furthermore, the present invention applies the photoanode loaded with Bi2O2Fe2O4 / WSe2 array to the electrolytic cell. Through the photoelectrocatalytic advanced oxidation technology, the activity of photocatalytic and electrocatalytic oxidation reactions is improved. The various components and materials have a synergistic effect, which improves the deep treatment efficiency of complex water quality. The photoelectrocatalytic advanced oxidation system has a strong redox ability under the action of an external electric field and light radiation. The photoanode loses electrons and generates holes under the excitation of electric energy and light radiation. The holes are highly oxidizing and can directly react with pollutants, or react with water molecules to form hydroxyl radicals (·OH) to indirectly oxidize pollutants; and the electrons move to the cathode in a directed manner under the action of an external electric field to gather. The highly reducing electrons can not only directly catalyze the precipitation of heavy metal ions, but also react with water to generate superoxide radicals (·O 2- ), indirectly oxidize pollutants.

[0101] Preferably, in S1, the temperature of the first aerobic reaction is 20°C to 35°C, and the ventilation volume is 100m 3 / h~150m 3 / h, time is 30h~90h.

[0102] Preferably, in S1, the temperature of the second aerobic reaction is 20°C to 35°C, the dissolved oxygen concentration is 3 mg / L to 6 mg / L, and the time is 7 d to 9 d.

[0103] For example, in S1, during the second aerobic reaction, the liquid level of the water in the biofilm pool remains unchanged during the intermittent introduction of the sewage to be treated and the discharge of the treated sewage; the time for intermittent introduction of the sewage to be treated and the discharge of the treated sewage is 12h~48h.

[0104] During the second aerobic reaction of S1 of the present invention, the effect of keeping the liquid level unchanged can be achieved by opening the water inlet and outlet of the biofilm pool at the same time. The opening time of the water inlet and outlet of the biofilm pool is 12h~48h, and the closing time is also 12h~48h, until the biofilm growth and biological acclimation of the porous biofilm carrier are completed after 5d~10d. During the second aerobic reaction, some microorganisms carry out denitrification reaction in the anoxic environment inside the pores of the porous biofilm carrier, and some microorganisms carry out nitrification reaction of nitrogen-containing substances in the aerobic environment outside the pores of the porous biofilm carrier. After the second aerobic reaction is completed, the COD of the treated purified water can reach below 80mg / L.

[0105] Preferably, in S1, after the second aerobic reaction is completed, the biofilm thickness of the porous biofilm carrier is 1.8 mm to 2 mm.

[0106] The basic principle of biofilm formation is to attach bacteria and other microorganisms in activated sludge to porous biofilm carriers, and form biofilms through continuous growth and development. These biofilms can decompose organic impurities in sewage. When sewage passes through the filler layer (porous biofilm carrier), the organic pollutants in the water are gradually decomposed by the microorganisms on the biofilm.

[0107] Preferably, in S1~S2, the COD of the sewage to be treated is 150mg / L~12000mg / L, the ammonia nitrogen value is 50mg / L~390mg / L, the BOD is 70mg / L~410mg / L, the suspended matter content is 100mg / L~190mg / L, and the heavy metal ion content is 10mg / L~180mg / L.

[0108] For example, in S2, 0.1wt% sodium hydroxide solution, 0.1wt% hydrochloric acid aqueous solution or 0.1wt% nitric acid aqueous solution is used to adjust the pH of the sewage to be treated, and sodium sulfate or potassium sulfate is used to adjust the conductivity of the sewage to be treated. The present invention adjusts the sewage to be treated to a specific pH range and conductivity range, which is conducive to the smooth progress of subsequent photoelectric catalytic treatment and saves electrical energy.

[0109] Preferably, in S2, the photoelectrocatalytic treatment time is 30 min to 120 min.

[0110] Preferably, in S2, the COD of the water purified by the photoelectric treatment is 105mg / L~820mg / L, the ammonia nitrogen value is 26mg / L~160mg / L, the BOD is 40mg / L~110mg / L, the suspended matter content is 50mg / L~105mg / L, and the heavy metal ion content is 6mg / L~60mg / L.

[0111] Preferably, in S3, the temperature of the third aerobic treatment is 20°C to 35°C, the dissolved oxygen concentration is 3 mg / L to 6 mg / L, and the time is 12h to 48h.

[0112] Preferably, in S3, the COD of the water purified by the biofilm pool is 10 mg / L~180 mg / L, the ammonia nitrogen value is 10 mg / L~63 mg / L, the BOD is 15 mg / L~80 mg / L, and the heavy metal ion content is 2 mg / L~10 mg / L.

[0113] Preferably, in S3, the COD of the purified water that meets the discharge standards is below 60 mg / L, the ammonia nitrogen value is below 15 mg / L, the BOD is below 20 mg / L, the suspended matter content is below 20 mg / L, and the heavy metal ion content is below 2 mg / L. BRIEF DESCRIPTION OF THE DRAWINGS

[0114] Figure 1 1 is a schematic diagram of the structure of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system 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 water inlet of the electrolytic cell, 1032 represents the water outlet of the electrolytic cell, 104 represents the power supply, and 105 represents the light source; 2 represents the suspended filler biofilm reactor, 201 represents the biofilm pool, 2011 represents the water inlet of the biofilm pool, 2012 represents the water outlet of the biofilm pool, 2013 represents the air outlet of the biofilm pool, 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 water pump; Figure 2 This is a SEM image of Bi2O2Fe2O4 in Example 3 of the present invention; Figure 3 This is a SEM image of the WSe2 array in Example 3 of the present invention; Figures 4 and 5 This is a SEM image of the Bi2O2Fe2O4 / WSe2 array in Example 3 of the present invention; Figure 6 2. XRD diagram of Bi2O2Fe2O4, Bi2O2Fe2O4 / WSe2 array and WSe2-Bi2O2Fe2O4 nanocomposite in Example 3 of the present invention. DETAILED DESCRIPTION

[0115] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0116] See also Figure 1 , the present invention provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, comprising: a photoelectrocatalytic advanced oxidation system 1 and a suspended filler biofilm reactor 2; The photoelectrocatalytic advanced oxidation system 1 comprises a photoanode 101, a photocathode 102, an electrolytic cell 103, a power source 104 and a light source 105; 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; The suspended filler biofilm reactor 2 comprises a biofilm pool 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 pool 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 pool 201; The water inlet 2011 of the biofilm pool 201 is connected to the water outlet 1032 of the electrolytic cell 103, and the water outlet 2012 of the biofilm pool 201 is connected to the water inlet 1031 of the electrolytic cell 103 for reflux and multiple circulation treatments.

[0117] In some embodiments, the photoanode 101 and the photocathode 102 are the same size.

[0118] In some embodiments, a stirring device is provided in the electrolytic cell 103 .

[0119] In some embodiments, the light source 105 uses a simulated sunlight system.

[0120] In some embodiments, a stirring device is provided in the biofilm pool 201 .

[0121] In some embodiments, the upper side wall of the biofilm pool 201 is provided with a gas outlet 2013 for discharging gas.

[0122] In some embodiments, a water storage device 3 is further connected between the photoelectrocatalytic advanced oxidation system 1 and the suspended filler biofilm reactor 2; The water inlet of the water storage device 3 is connected to the water outlet 1032 of the electrolytic cell 103 , and the water outlet of the water storage device 3 is connected to the water inlet 2011 of the biofilm pool 201 .

[0123] In some embodiments, a peristaltic water pump 4 is connected between the water outlet 1032 of the electrolytic cell 103 and the water inlet 2011 of the biofilm pool 201, and a peristaltic water pump 4 is connected between the water outlet 2012 of the biofilm pool 201 and the water inlet 1031 of the electrolytic cell 103, which are used to control the water inlet flow rate and the water outlet flow rate, respectively.

[0124] In some embodiments, a peristaltic water pump 4 is connected between the water outlet 1032 of the electrolytic cell 103 and the water inlet of the water storage device 3 , and a peristaltic water pump 4 is connected between the water outlet of the water storage device 3 and the water inlet 2011 of the biofilm pool 201 .

[0125] In the present invention, the visible light radiation is provided by the light source of the HSX-F300 simulated sunlight system, and the aeration device is a RB-71D sewage aeration blower with adjustable power (100W-750W).

[0126] In the present invention, materials not specifically specified are all commercially available products. Water used in the present invention is all deionized water. Sewage used in the present invention is wastewater from an industrial park. The activated sludge of the present invention comes from the activated sludge in the aerobic tank of a sewage treatment plant as a microbial source.

[0127] Example 1 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system (see Figure 1 ), including: a photoelectrocatalytic advanced oxidation system 1, a suspended filler biofilm reactor 2 and a water storage device 3.

[0128] The photoelectrocatalytic advanced oxidation system 1 comprises a photoanode 101, a photocathode 102, an electrolytic cell 103, a power source 104 and a light source 105. 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 source 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.

[0129] The photoanode 101 and the photocathode 102 have the same size. A stirring device is provided in the electrolytic cell 103 .

[0130] The suspended filler biofilm reactor 2 comprises a biofilm pool 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 pool 201 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 pool 201.

[0131] A stirring device is provided in the biofilm pool 201. An air outlet 2013 is provided on the upper side wall of the biofilm pool 201 for exhausting gas.

[0132] The water inlet of the water storage device 3 is connected to the water outlet 1032 of the electrolytic cell 103, and the water outlet of the water storage device 3 is connected to the water inlet 2011 of the biofilm pool 201; the water outlet 2012 of the biofilm pool 201 is connected to the water inlet 1031 of the electrolytic cell 103, for reflux and multiple circulation treatment. A peristaltic water pump 4 is connected between the water outlet 1032 of the electrolytic cell 103 and the water inlet of the water storage device 3, a peristaltic water pump 4 is connected between the water outlet of the water storage device 3 and the water inlet 2011 of the biofilm pool 201, and a peristaltic water pump 4 is connected between the water outlet 2012 of the biofilm pool 201 and the water inlet 1031 of the electrolytic cell 103, for controlling the water inlet flow rate and the water outlet flow rate, respectively.

[0133] 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-containing layer loaded on the WSe2 array layer, and the Bi2O2Fe2O4-containing layer also includes a Φ150nm×5μm carbon nanofiber. The mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofiber in the photoanode material is 200:10:0.8. The anode substrate is a molybdenum mesh of 50mm×200mm×3mm, the thickness of the WSe2 array layer is 3μm, and the thickness of the Bi2O2Fe2O4-containing layer is 80nm.

[0134] The method for preparing the above-mentioned photoanode comprises the following steps: SI, Preparation of Bi2O2Fe2O4: Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 2.3M ammonium acetate solution and 2.3M acetic acid solution were added into 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 which time the pH of the system was 3, and the suspension was obtained after the hydrolysis reaction was carried out at 20°C for 45 minutes; Urea was then used to adjust the pH value of the suspension to 7.1, and the first hydrothermal reaction was carried out in a high-pressure reactor at 180°C. After keeping warm for 10 hours, the mixture was cooled to room temperature, the solid and the liquid were separated, and the solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 14 nm.

[0135] SII, the anode substrate was placed in acetone and water in turn, ultrasonicated for 10 minutes respectively, and then immersed in a mixture of WSe2 (average particle size of 12nm) and water (the mass ratio of WSe2 to water is 1:80) for 30 minutes after natural drying. Then it was taken out and placed in a reactor at 100℃ for the second hydrothermal reaction. After keeping warm for 40 minutes, the primary electrode was obtained.

[0136] SIII, immersing the primary electrode in a mixture of WSe2, KH560 and 60wt% polyvidone aqueous solution, the mass ratio of WSe2, KH560 and polyvidone aqueous solution is 2:1:10, and carrying out the third hydrothermal reaction in a reactor at 80°C, keeping the temperature for 7h to form a WSe2 array layer, cooling to room temperature, washing with water and drying to obtain a WSe2 array electrode.

[0137] SIV, using a coating machine, a mixed solution 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 on the WSe2 array electrode, and after natural drying for 4 minutes, it is calcined at 165°C for 120 minutes to form a Bi2O2Fe2O4 layer, and then cooled to room temperature to obtain a photoanode containing a Bi2O2Fe2O4 / WSe2 array.

[0138] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0139] The photocathode 102 is a plated tungsten alloy electrode with the same size as the photoanode 101 , the volume of the electrolytic cell 103 is 20 L, and the power supply 104 is a 80V DC power supply.

[0140] The volume of the biofilm pool 201 is 250 L, and the porous biofilm carrier has a pore size of 300 nm and a specific gravity of 0.8 g / cm 3 The amount of polyurethane hydrogel, porous biofilm carrier added was 4g / L, the amount of activated sludge added was 0.15kg / L, and the amount of 450-mesh coconut shell powder added was 0.1g / L.

[0141] Example 2 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system (see Figure 1 ), including: a photoelectrocatalytic advanced oxidation system 1, a suspended filler biofilm reactor 2 and a water storage device 3.

[0142] The positional relationship and connection conditions of the photoelectrocatalytic advanced oxidation system 1, the suspended filler biofilm reactor 2 and the water storage device 3 are the same as those in Example 1 and will not be described in detail.

[0143] 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-containing layer loaded on the WSe2 array layer, and the Bi2O2Fe2O4-containing layer also includes a Φ160nm×10μm carbon nanofiber. The mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofiber in the photoanode material is 200:15:1. The anode substrate is a molybdenum mesh of 80mm×250mm×4mm, the thickness of the WSe2 array layer is 4μm, and the thickness of the Bi2O2Fe2O4-containing layer is 100nm.

[0144] The method for preparing the above-mentioned photoanode comprises the following steps: SI, Preparation of Bi2O2Fe2O4: Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 2M ammonium acetate solution and 2M acetic acid solution were added into water, the mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution and water was 3:6:0.6:0.15:110, the pH of the system was 4 at this time, and the suspension was obtained after the hydrolysis reaction was carried out at 25°C for 40 minutes; Urea was then used to adjust the pH value of the suspension to 7.5, and the first hydrothermal reaction was carried out in a high-pressure reactor at 190°C. After being kept warm for 9.5 hours, the mixture was cooled to room temperature, the solid-liquid was separated, and the solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 60 nm.

[0145] SII, the anode substrate was placed in acetone and water in turn, ultrasonicated for 15 minutes respectively, and naturally dried, then immersed in a mixture of WSe2 (average particle size of 60nm) and water (the mass ratio of WSe2 to water is 2:85) for 40 minutes, and then taken out and placed in a reactor at 110℃ for the second hydrothermal reaction. After keeping warm for 30 minutes, the primary electrode was obtained.

[0146] SIII, immersing the primary electrode in a mixture of WSe2, KH560 and 50wt% polyvidone aqueous solution, the mass ratio of WSe2, KH560 and polyvidone aqueous solution is 3:2:12, and carrying out the third hydrothermal reaction in a reactor at 90°C, keeping warm for 7h to form a WSe2 array layer, cooling to room temperature, washing with water and drying to obtain a WSe2 array electrode.

[0147] SIV, using a coating machine, a mixed solution 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 on the WSe2 array electrode, and after natural drying for 6 minutes, it is calcined at 180°C for 110 minutes to form a Bi2O2Fe2O4 layer, and then cooled to room temperature to obtain a photoanode containing a Bi2O2Fe2O4 / WSe2 array.

[0148] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0149] The photocathode 102 is a titanium mesh with the same size as the photoanode 101, the volume of the electrolytic cell 103 is 100L, and the power supply 104 is a 80V DC power supply.

[0150] The volume of the biofilm pool 201 is 380 L, and the porous biofilm carrier has a pore size of 400 nm and a specific gravity of 0.84 g / cm 3 The amount of polyurethane sponge, porous biofilm carrier added was 8g / L, activated sludge added was 0.25kg / L, and 500-mesh coconut shell powder added was 0.2g / L.

[0151] Example 3 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system (see Figure 1 ), including: a photoelectrocatalytic advanced oxidation system 1, a suspended filler biofilm reactor 2 and a water storage device 3.

[0152] The positional relationship and connection conditions of the photoelectrocatalytic advanced oxidation system 1, the suspended filler biofilm reactor 2 and the water storage device 3 are the same as those in Example 1 and will not be described in detail.

[0153] 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-containing layer loaded on the WSe2 array layer, and the Bi2O2Fe2O4-containing layer also includes a Φ180nm×15μm carbon nanofiber. The mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofiber in the photoanode material is 200:35:1.3. The anode substrate is a 100mm×300mm×3mm nickel foam, the thickness of the WSe2 array layer is 4μm, and the thickness of the Bi2O2Fe2O4-containing layer is 180nm.

[0154] The method for preparing the above-mentioned photoanode comprises the following steps: SI, Preparation of Bi2O2Fe2O4: 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 into 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, the pH of the system was 4 at this time, and the suspension was obtained after the hydrolysis reaction was carried out at 25°C for 40 minutes; Urea was then used to adjust the pH value of the suspension to 7.8, and the first hydrothermal reaction was carried out in a high-pressure reactor at 200°C. After keeping the temperature for 9 hours, the mixture was cooled to room temperature, the solid-liquid was separated, and the solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 120 nm.

[0155] The above-mentioned product was subjected to electron microscope scanning and X-ray diffraction test, and the results were as follows: Figure 2 and Figure 6 shown.

[0156] SII, the anode substrate was placed in acetone and water in turn, ultrasonicated for 12 minutes respectively, naturally dried, and then immersed in a mixture of WSe2 (average particle size of 160nm) and water (the mass ratio of WSe2 to water is 3:90) for 50 minutes, and then taken out and placed in a reactor at 110℃ for the second hydrothermal reaction. After keeping warm for 30 minutes, the primary electrode was obtained.

[0157] SIII, immersing the primary electrode in a mixture of WSe2, KH560 and 50wt% polyvidone aqueous solution, the mass ratio of WSe2, KH560 and polyvidone aqueous solution is 4:3:15, and carrying out the third hydrothermal reaction in a reactor at 110°C, keeping the temperature for 6h to form a WSe2 array layer, cooling to room temperature, washing with water and drying to obtain a WSe2 array electrode.

[0158] The above-mentioned product was subjected to electron microscope scanning test, and the results were as follows: Figure 3 shown.

[0159] SIV, using a coating machine, a mixed solution 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 on the WSe2 array electrode, and after natural drying for 8 minutes, it is calcined at 240°C for 100 minutes to form a Bi2O2Fe2O4 layer, and then cooled to room temperature to obtain a photoanode containing a Bi2O2Fe2O4 / WSe2 array.

[0160] The surface of the obtained product was scanned by electron microscope and tested by X-ray diffraction. Figures 4 and 5 and Figure 6To further verify the composition of the Bi2O2Fe2O4 / WSe2 array, a mixture of WSe2 and Bi2O2Fe2O4 (denoted as WSe2-Bi2O2Fe2O4) with a mass ratio of 200:30 was subjected to X-ray diffraction testing. The results are shown in Figure 6 shown.

[0161] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0162] The photocathode 102 is a graphite felt electrode of the same size as the photoanode 101 , the volume of the electrolytic cell 103 is 120 L, and the power supply 104 is a 100 V DC power supply.

[0163] The volume of the biofilm pool 201 is 460 L, and the porous biofilm carrier has a pore size of 500 nm and a specific gravity of 0.83 g / cm 3 The amount of polyethylene filler, porous biofilm carrier added was 12g / L, activated sludge added was 0.35kg / L, and 550-mesh coconut shell powder added was 0.3g / L.

[0164] Example 4 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system (see Figure 1 ), including: a photoelectrocatalytic advanced oxidation system 1, a suspended filler biofilm reactor 2 and a water storage device 3.

[0165] The positional relationship and connection conditions of the photoelectrocatalytic advanced oxidation system 1, the suspended filler biofilm reactor 2 and the water storage device 3 are the same as those in Example 1 and will not be described in detail.

[0166] 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-containing layer loaded on the WSe2 array layer, and the Bi2O2Fe2O4-containing layer also includes a Φ200nm×20μm carbon nanofiber. The mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofiber in the photoanode material is 200:46:1.5. The anode substrate is a titanium mesh of 100mm×400mm×4.5mm, the thickness of the WSe2 array layer is 5μm, and the thickness of the Bi2O2Fe2O4-containing layer is 200nm.

[0167] The method for preparing the above-mentioned photoanode comprises the following steps: SI, Preparation of Bi2O2Fe2O4: Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, 1.7M ammonium acetate solution and 1.7M acetic acid solution were added into water, the mass ratio of Na2Fe2O4·2H2O, Bi(NO3)3·5H2O, polyvinyl alcohol, ammonium acetate solution and water was 8:16:1:0.45:160, the pH of the system was 5, and the suspension was obtained after hydrolysis reaction at 30°C for 30 minutes; Urea was then used to adjust the pH value of the suspension to 7.5, and the first hydrothermal reaction was carried out in a high-pressure reactor at 220°C. After being kept warm for 8 hours, the mixture was cooled to room temperature, the solid and the liquid were separated, and the solid was washed and dried to obtain Bi2O2Fe2O4 with an average particle size of 140 nm.

[0168] SII, the anode substrate was placed in acetone and water in turn, ultrasonicated for 13 minutes respectively, naturally dried, and then immersed in a mixture of WSe2 (average particle size of 190nm) and water (the mass ratio of WSe2 to water is 4:100) for 60 minutes, and then taken out and placed in a 120℃ reactor for the second hydrothermal reaction. After keeping warm for 25 minutes, the primary electrode was obtained.

[0169] SIII, immersing the primary electrode in a mixture of WSe2, KH560 and 40wt% polyvidone aqueous solution, the mass ratio of WSe2, KH560 and polyvidone aqueous solution is 5:4:20, and carrying out the third hydrothermal reaction in a reactor at 120°C, keeping the temperature for 5h to form a WSe2 array layer, cooling to room temperature, washing with water and drying to obtain a WSe2 array electrode.

[0170] SIV, using a coating machine, a mixed solution 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 on the WSe2 array electrode, and after natural drying for 0 min, it is calcined at 260°C for 80 min to form a Bi2O2Fe2O4 layer, and then cooled to room temperature to obtain a photoanode containing a Bi2O2Fe2O4 / WSe2 array.

[0171] It should be noted that this embodiment does not limit the order of SI and SII~SIII.

[0172] The photocathode 102 is a carbon rod of the same size as the photoanode 101, the volume of the electrolytic cell 103 is 150L, ​​and the power supply 104 is a 180V DC power supply.

[0173] The volume of the biofilm pool 201 is 600 L, and the porous biofilm carrier has a pore size of 600 nm and a specific gravity of 0.85 g / cm 3The amount of polypropylene filler, porous biofilm carrier added was 18g / L, activated sludge added was 0.5kg / L, and 600-mesh coconut shell powder added was 0.4g / L.

[0174] Example 5 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the Bi2O2Fe2O4 in the Bi2O2Fe2O4-containing layer of the photoanode is replaced with ferrous tungstate.

[0175] The preparation method of the above-mentioned photoanode is similar to that of Example 3, except that step S1 is deleted, and Bi2O2Fe2O4 in SIV is replaced with an equal mass of ferrous tungstate. The remaining conditions are the same as those of Example 3 and will not be described in detail.

[0176] Example 6 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 2, except that the Bi2O2Fe2O4 in the Bi2O2Fe2O4-containing layer of the photoanode is replaced with BiVO4.

[0177] The preparation method of the above-mentioned photoanode is similar to that of Example 2, except that step SI is deleted and Bi2O2Fe2O4 in SIV is replaced with an equal mass of BiVO4. The remaining conditions are the same as those of Example 2 and will not be described in detail.

[0178] Example 7 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the WSe2 in the WSe2 array layer of the photoanode is replaced with TiO2.

[0179] 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 those of Example 3 and will not be described in detail.

[0180] Example 8 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 2, except that the WSe2 in the WSe2 array layer of the photoanode is replaced with ZnO.

[0181] 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. The remaining conditions are the same as those of Example 2 and will not be described in detail.

[0182] Example 9 This embodiment provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the Bi2O2Fe2O4 in the Bi2O2Fe2O4 layer of the photoanode is replaced by ferrous tungstate, and the WSe2 in the WSe2 array layer is replaced by TiO2.

[0183] The preparation method of the above photoanode is similar to that of Example 3, except that step SI is deleted, 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 those of Example 3 and will not be repeated here.

[0184] Comparative Example 1 This comparative example provides a photocatalytic-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the photocatalytic advanced oxidation system is replaced by a photocatalytic system that does not include a power source, a photoanode, and a photocathode (it can be understood that the photocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 3 is used, and the power source is not powered when it is used). The remaining conditions are the same as those in Example 3 and will not be repeated.

[0185] Comparative Example 2 This comparative example provides an electrocatalytic-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the photoelectrocatalytic advanced oxidation system is replaced by an electrocatalytic system that does not include a light source (it can be understood that the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 3 is used without turning on the light source). The remaining conditions are the same as those of Example 3 and will not be repeated here.

[0186] Comparative Example 3 This comparative example provides a suspended filler biofilm reactor, which is the same as the suspended filler biofilm reactor 2 of Example 3 and will not be described in detail.

[0187] Comparative Example 4 This comparative example provides a photoelectrocatalytic advanced oxidation system, which is the same as the photoelectrocatalytic advanced oxidation system 1 of Example 3 and will not be described in detail.

[0188] Comparative Example 5 This comparative example provides a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, which is similar to Example 3, except that the suspended filler biofilm reactor 2 does not contain coconut shell powder. The remaining conditions are the same as those in Example 3 and will not be repeated.

[0189] Application Example 1 This application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 1, including the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The treated sewage and activated sludge were introduced into the biofilm tank (the mass ratio of treated sewage to activated sludge was 3:1), and the aeration device 202 was turned on at 35°C and a ventilation volume of 140m 3 / h for 30 hours; add porous biofilm carriers and coconut shell powder, and carry out the second aerobic reaction at 35°C and a dissolved oxygen concentration of 3 mg / L (during the second aerobic reaction, it is necessary to intermittently introduce the sewage to be treated and discharge the treated sewage, and the water level in the biofilm pool remains unchanged during this process; the opening time of the water inlet and outlet of the biofilm pool is 12 hours, and the closing time is 12 hours). After 6 days, the biofilm thickness of the porous biofilm carrier is 1.8 mm, completing the biofilm growth and biological acclimation of the porous biofilm carrier, and the treated purified water is discharged.

[0190] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH value of the sewage to be treated to 6, the conductivity to 250μS / cm, start the photoelectrocatalytic advanced oxidation system, and after 30 minutes of photoelectrocatalytic treatment, obtain the photoelectrocatalytic purified effluent.

[0191] S3, the photoelectric treatment purified water is introduced into the biofilm pool, and the third aerobic reaction is carried out at 35°C and a dissolved oxygen concentration of 3 mg / L for 12 hours to obtain the biofilm pool purified water.

[0192] S4, returning the purified water from the biofilm pool to the electrolytic cell, repeating steps S2 to S3 once, and obtaining purified water that meets the discharge standards.

[0193] Peristaltic water pump 4 runs all day long, and the treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage is evaluated by real-time monitoring of COD and ammonia nitrogen values ​​of inlet and outlet water (see Table 1).

[0194] Application Example 2 This application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 2, including the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The treated sewage and activated sludge were introduced into the biofilm tank (the mass ratio of treated sewage to activated sludge was 4:1), and the aeration device 202 was turned on at 25°C and a ventilation volume of 100m 3 / h for 50 hours; add porous biofilm carriers and coconut shell powder, and carry out the second aerobic reaction at 25°C and a dissolved oxygen concentration of 4 mg / L (during the second aerobic reaction, it is necessary to intermittently introduce the sewage to be treated and discharge the treated sewage, and the liquid level of the water in the biofilm pool remains unchanged during this process; the opening time of the water inlet and outlet of the biofilm pool is 16 hours, and the closing time is 168 hours). After 8 days, the biofilm thickness of the porous biofilm carrier is 1.9 mm, completing the biofilm growth and biological acclimation of the porous biofilm carrier, and the treated purified water is discharged.

[0195] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH value of the sewage to be treated to 5, and the conductivity to 550μS / cm, start the photoelectrocatalytic advanced oxidation system, and after 60 minutes of photoelectrocatalytic treatment, obtain the photoelectrocatalytic purified effluent.

[0196] S3, the photoelectric treatment purified water is introduced into the biofilm pool, and the third aerobic reaction is carried out at 25°C and a dissolved oxygen concentration of 4 mg / L for 16 hours to obtain the biofilm pool purified water, that is, the purified water that meets the discharge standards.

[0197] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0198] Application Example 3 This application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 3, including the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The sewage to be treated and the activated sludge are introduced into the biofilm tank, and the aeration device 202 is turned on. 3 / h for 70 hours; add porous biofilm carriers and coconut shell powder, and carry out the second aerobic reaction at 30°C and a dissolved oxygen concentration of 5 mg / L (during the second aerobic reaction, it is necessary to intermittently introduce the sewage to be treated and discharge the treated sewage, and the water level in the biofilm pool remains unchanged during this process; the opening time of the water inlet and outlet of the biofilm pool is 36 hours, and the closing time is 36 hours). After 9 days, the biofilm thickness of the porous biofilm carrier is 2 mm, completing the biofilm growth and biological acclimation of the porous biofilm carrier, and the treated purified water is discharged.

[0199] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH value of the sewage to be treated to 6, and the conductivity to 750μS / cm, start the photoelectrocatalytic advanced oxidation system, and after 100 minutes of photoelectrocatalytic treatment, obtain the photoelectrocatalytic purified effluent.

[0200] S3, the photoelectric treatment purified water is introduced into the biofilm pool, and the third aerobic reaction is carried out at 30°C and a dissolved oxygen concentration of 5 mg / L for 36 hours to obtain the biofilm pool purified water, that is, the purified water that meets the discharge standards.

[0201] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0202] Application Example 4 This application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, using the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Example 4, including the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The sewage to be treated and the activated sludge are introduced into the biofilm tank, and the aeration device 202 is turned on. 3 / h for 90 hours; add porous biofilm carriers and coconut shell powder, and carry out the second aerobic reaction at 20°C and a dissolved oxygen concentration of 6 mg / L (during the second aerobic reaction, it is necessary to intermittently introduce the sewage to be treated and discharge the treated sewage, and the liquid level of the water in the biofilm pool remains unchanged during this process; the opening time of the water inlet and outlet of the biofilm pool is 40 hours, and the closing time is 48 hours). After 7 days, the biofilm thickness of the porous biofilm carrier is 1.8 mm, completing the biofilm growth and biological acclimation of the porous biofilm carrier, and the treated purified water is discharged.

[0203] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH of the sewage to be treated to 3, the conductivity to 1000μS / cm, start the photoelectrocatalytic advanced oxidation system, and after 120 minutes of photoelectrocatalytic treatment, obtain the photoelectrocatalytic purified effluent.

[0204] S3, the photoelectric treatment purified water is introduced into the biofilm pool, and the third aerobic reaction is carried out at 20°C and a dissolved oxygen concentration of 6 mg / L for 48 hours to obtain the biofilm pool purified water, that is, the purified water that meets the discharge standards.

[0205] Through real-time monitoring of COD and ammonia nitrogen values ​​in influent and effluent water, the treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated (see Table 1).

[0206] Application Examples 5~9 This application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, which is similar to application example 3, except that the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of embodiments 5 to 9 is used respectively. The remaining conditions and steps are the same as those of application example 3 and will not be repeated.

[0207] Application Comparative Example 1 This comparative application example provides a sewage treatment method coupled with a photocatalytic-suspended filler biofilm reactor, which is similar to Application Example 3, except that the photocatalytic-suspended filler biofilm reactor coupling system of Comparative Example 1 is used. Specifically, the following steps are included: S1 is the same as Application Example 3 and will not be described in detail.

[0208] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH value of the sewage to be treated to 5, and the conductivity to 550μS / cm, start the photocatalytic system, and after 60 minutes of photocatalytic treatment, obtain the photoelectric treatment purified water.

[0209] S3 is the same as application example 3 and will not be described in detail.

[0210] The treatment effect of the photocatalytic-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0211] Application Comparative Example 2 This comparative application example provides a sewage treatment method coupled with an electrocatalytic-suspended filler biofilm reactor, which is similar to Application Example 3, except that the electrocatalytic-suspended filler biofilm reactor coupling system of Comparative Example 2 is used. Specifically, the following steps are included: S1 is the same as Application Example 3 and will not be described in detail.

[0212] S2, introduce the sewage to be treated into the electrolytic cell, adjust the pH value of the sewage to be treated to 5, and the conductivity to 550μS / cm, start the electrocatalytic system, and after 60 minutes of electrocatalytic treatment, obtain the photoelectric treatment purified water.

[0213] S3 is the same as application example 3 and will not be described in detail.

[0214] The treatment effect of the electrocatalytic-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0215] Application Comparative Example 3 This comparative example provides a wastewater treatment method using a suspended filler biofilm reactor, which is similar to Example 3, except that the suspended filler biofilm reactor of Comparative Example 3 is used. Specifically, the following steps are included: S1 is the same as Application Example 3 and will not be described in detail.

[0216] S2, introducing the sewage to be treated into the biofilm pool, and carrying out the third aerobic reaction at 25°C and a dissolved oxygen concentration of 4 mg / L for 16 hours to obtain the purified effluent from the biofilm pool.

[0217] The treatment effect of the suspended filler biofilm reactor on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0218] Application Comparative Example 4 This comparative application example provides a sewage treatment method coupled with a photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor, which is similar to Application Example 3, except that: the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Comparative Example 5 is used, and coconut shell powder is not added to S1. Specifically, the following steps are included: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The treated sewage and activated sludge were introduced into the biofilm tank (the mass ratio of treated sewage to activated sludge was 4:1), and the aeration device 202 was turned on at 25°C and a ventilation volume of 100m 3 / h for 50 hours; add porous biofilm carriers, and carry out the second aerobic reaction at 25°C and a dissolved oxygen concentration of 4 mg / L (during the second aerobic reaction, it is necessary to intermittently introduce the sewage to be treated and discharge the treated sewage, and the liquid level of the water in the biofilm pool remains unchanged during this process; the opening time of the water inlet and outlet of the biofilm pool is 16 hours, and the closing time is 168 hours). After 8 days, the biofilm thickness of the porous biofilm carrier is 1.6 mm, completing the biofilm growth and biological acclimation of the porous biofilm carrier, and the treated purified water is discharged.

[0219] S2~S3 are the same as those in Application Example 3 and will not be described in detail.

[0220] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0221] Application Comparative Example 5 This comparative application example provides a sewage treatment method coupled with photoelectrocatalytic advanced oxidation and suspended filler biofilm reactor, which is similar to Application Example 3, except that: in S2, the pH of the sewage to be treated is adjusted to 8. The remaining conditions and steps are the same as those in Application Example 3 and will not be repeated.

[0222] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0223] Application Comparative Example 6 This comparative application example provides a sewage treatment method coupled with photoelectrocatalytic advanced oxidation and suspended filler biofilm reactor, which is similar to Application Example 3, except that: in S2, the conductivity of the sewage to be treated is adjusted to 200 μS / cm. The remaining conditions and steps are the same as those in Application Example 3 and will not be repeated.

[0224] The treatment effect of the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system on sewage was evaluated by real-time monitoring of the COD and ammonia nitrogen values ​​of the inlet and outlet water (see Table 1).

[0225] Table 1 Inlet and outlet water performance indicators of application examples and comparative examples

[0226] As can be seen from Table 1, after the sewage was treated by the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system of Examples 2 to 4, the COD, ammonia nitrogen, BOD, SS and chromaticity test results of the effluent performance indicators were better than the national primary standards, indicating that the photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system provided by the present invention can effectively treat industrial sewage in depth.

[0227] Compared with Examples 2 to 4 (Application Examples 2 to 4), Examples 5 to 9 (Application Examples 5 to 9) use non-Bi2O2Fe2O4 semiconductors or non-WSe2 arrays as photoanodes. After sewage treatment, it can be seen from the test results of the effluent performance that the values ​​of COD and ammonia nitrogen are significantly increased, and the effluent ammonia nitrogen value is higher than the national first-level standard. This shows that after replacing the Bi2O2Fe2O4 semiconductor nanomaterial or WSe2 array in the photoanode, the efficiency of its photoelectrocatalytic oxidation reaction is reduced, and the synergistic effect of the photocatalysis and electrocatalytic oxidation of WSe2 and Bi2O2Fe2O4 is not exerted, so that the water treatment performance of the entire system is significantly reduced compared with Examples 1 to 4. The present invention selects nano WSe2 and Bi2O2Fe2O4 semiconductor composites, which can give full play to the synergistic effect of the composite material photoanode and cathode, and can generate a large number of electrons and holes under the excitation of light and external electric field. After the separation of electrons and holes, they move in a directional manner, gather at the positive and negative poles and generate a large number of active free radicals. After the active free radicals react with pollutants in water, the purification efficiency of water quality can be significantly improved.

[0228] Compared with Example 3 (Application Example 3), Comparative Example 1 (Application Comparative Example 1) only provides a photocatalytic system. After sewage treatment, it can be seen from the test results of the effluent performance that the values ​​of COD and ammonia nitrogen have increased significantly, exceeding the national first-level standard. This shows that the power supply affects the water treatment capacity of the photoelectric catalytic advanced oxidation system. In the case of only light, some of the electrons and holes generated by the photoanode are not separated and moved in a directional manner in time, and the electrons and holes are recombined, which weakens the photocurrent and the density of holes, and reduces the photoelectric conversion efficiency. The redox performance of the advanced oxidation reaction system cannot play the original synergistic role, which leads to a significant decrease in the water treatment effect of the coupling system and a significant increase in the effluent COD value.

[0229] Compared with Example 3 (Application Example 3), Comparative Example 2 (Application Comparative Example 2) only provides an electrocatalytic system. After sewage treatment, it can be seen from the test results of the effluent performance that COD has decreased significantly, but the ammonia nitrogen value has increased significantly, both of which exceed the national first-level standard. This shows that the effect of single electrochemical treatment is not ideal. The photoanode can only generate electrons and holes when excited by light, improving the photoelectric conversion efficiency. The electrocatalytic treatment with only the electric field effect is difficult to exert the synergy of the photocatalytic reaction and electrocatalytic reaction between the Bi2O2Fe2O4 semiconductor and the WSe2 array, resulting in a decrease in the water treatment effect of the coupling system and a significant increase in the effluent ammonia nitrogen value.

[0230] Compared with Example 3 (Application Example 3), Comparative Example 3 (Application Comparative Example 3) only contains a suspended filler biofilm reactor. After sewage treatment, it can be seen from the effluent performance test results that the COD and ammonia nitrogen values ​​are greatly increased. This shows that a single suspended filler biofilm reactor cannot take into account the efficiency and biodegradability of photoelectrocatalytic advanced oxidation sewage treatment. After losing the synergistic complementarity with the photoelectrocatalytic system, the purification effect is affected. Comparative Example 4 only contains a photoelectrocatalytic advanced oxidation system. After sewage treatment, it can be seen from the performance test results of the photoelectric treatment purified effluent of Application Example 3 and the biofilm pool purified effluent that the treatment efficiency of COD, BOD and ammonia nitrogen is relatively weak, especially the ammonia nitrogen value is particularly significant. This shows that the single photoelectrocatalytic advanced oxidation sewage treatment lacks the microbial digestion effect of MBBR on organic pollutants in sewage, especially the nitrification and denitrification of ammonia nitrogen, and the purification efficiency is significantly adversely affected. The only photoelectrocatalytic advanced oxidation system cannot take into account the requirements of energy consumption control and circulation treatment, and the sewage treatment effect is also significantly lower than the coupling system, and the effluent parameters do not meet the national first-level standards.

[0231] Compared with Example 3 (Application Example 3), the MBBR of Comparative Example 5 (Application Comparative Example 4) does not contain coconut shell powder. After sewage treatment, the effluent performance test results show that the treatment efficiency of COD, BOD and ammonia nitrogen is not as expected, and the values ​​are greatly increased, especially the sewage chroma is high. This shows that adding coconut shell powder to the activated sludge of MBBR can significantly improve the sewage treatment capacity of the coupling system, and the lack of coconut shell powder cannot achieve the effect of deep sewage treatment.

[0232] Compared with Application Example 3, Application Comparative Examples 5-6 changed the pH and conductivity of the wastewater to be treated in the photoelectrocatalytic advanced oxidation system. After the wastewater was treated, the effluent performance test results showed that all indicators of the effluent could not meet the national standards. This shows that pH and conductivity in the operating parameters have an important influence on the water treatment efficiency of the coupled process system.

[0233] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system, characterized in that: include: Photoelectrocatalytic advanced oxidation systems and suspended filler biofilm reactors; The photoelectrocatalytic advanced oxidation system comprises 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 supply through wires; the light source is located outside the electrolytic cell and is used to irradiate the electrolytic cell with light; The suspended filler biofilm reactor comprises a biofilm tank, an aeration device, activated sludge, a porous biofilm carrier and coconut shell powder; The aeration device is located below the biofilm pool and is used to create an aerobic environment; the activated sludge, porous biofilm carrier and coconut shell powder are located in the biofilm pool; The water inlet of the biofilm pool is connected to the water outlet of the electrolytic cell, and the water outlet of the biofilm pool is connected to the water inlet of the electrolytic cell for reflux and multiple circulation treatments.

2. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 1, characterized in that: The photoanode comprises an anode substrate and a photoanode material loaded on the anode substrate; The photoanode material includes a WSe2 array layer and a Bi2O2Fe2O4-containing layer supported on the WSe2 array layer.

3. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 2, characterized in that: The thickness of the WSe2 array layer is 3 μm to 5 μm, and the thickness of the Bi2O2Fe2O4-containing layer is 80 nm to 200 nm.

4. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 2 or 3, characterized in that: The Bi2O2Fe2O4-containing layer further comprises carbon nanofibers; the carbon nanofibers have a diameter of 150nm to 200nm and a length of 5μm to 20μm; The mass ratio of WSe2, Bi2O2Fe2O4 and carbon nanofibers in the photoanode material is 200:(10~50):(0.8~1.6).

5. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 4, characterized in that: The preparation method of Bi2O2Fe2O4 comprises the following steps: Fe2O4 2- Salt, bismuth salt, emulsifier, ammonium acetate solution and acidic regulator are added to water, and a hydrolysis reaction is carried out under acidic conditions to obtain a suspension; after adjusting the pH of the suspension to be weakly alkaline, a first hydrothermal reaction is carried out to obtain Bi2O2Fe2O4; The method for preparing the photoanode comprises the following steps: Sa, immersing the anode substrate in a mixture of WSe2 and water to perform a second hydrothermal reaction to obtain a primary electrode; Sb, immersing the primary electrode in a mixed solution of WSe2, a silane coupling agent and a co-solvent, performing a third hydrothermal reaction to form a WSe2 array layer, thereby obtaining a WSe2 array electrode; Sc, coating a mixed solution of Bi2O2Fe2O4, an adhesive and a solvent on the WSe2 array electrode, and then calcining to form a Bi2O2Fe2O4 layer to obtain a photoanode.

6. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 5, characterized in that: The Fe2O4 2- The salt comprises sodium ferrite, the bismuth salt comprises bismuth nitrate, the emulsifier comprises polyvinyl alcohol, the concentration of the ammonium acetate solution is 1.7M to 2.3M, and the acidic regulator comprises 1.7M to 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 urea is used to adjust the pH of the suspension to 7-8; and / or The hydrolysis reaction temperature is 20°C to 30°C, and the reaction time is 30min to 50min; and / or The temperature of the first hydrothermal reaction is 180° C. to 220° C., and the reaction time is 8 h to 10 h; 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°C to 120°C, and the reaction time is 25min to 40min; and / or In Sb and Sc, the cosolvent comprises 40 wt % to 60 wt % of a polyvidone 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 Sb, the temperature of the third hydrothermal reaction is 80°C to 120°C, and the reaction time is 4h to 8h; and / or In Sc, the mixed liquid further includes carbon nanofibers; and / or In Sc, the adhesive comprises polyethylene dioxythiophene; and / or In Sc, the mass ratio of Bi2O2Fe2O4, adhesive and solvent is (6-32):(1-8):(10-80); and / or In Sc, the calcination temperature is 160° C. to 260° C., and the calcination time is 80 min to 120 min.

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

8. The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to claim 1, characterized in that: A water storage device is also connected between the photoelectrocatalytic advanced oxidation system and the suspended filler biofilm reactor; The water inlet of the water storage device is connected to the water outlet of the electrolytic cell, and the water outlet of the water storage device is connected to the water inlet of the biofilm pool; A peristaltic water pump is connected between the water outlet of the electrolytic cell and the water inlet of the water storage device, a peristaltic water pump is connected between the water outlet of the water storage device and the water inlet of the biofilm pool, and a peristaltic water pump is connected between the water outlet of the biofilm pool and the water inlet of the electrolytic cell, which are used to control the water inlet flow rate and the water outlet flow rate, respectively.

9. A sewage treatment method coupled with a photoelectrocatalytic advanced oxidation and a suspended filler biofilm reactor, characterized in that: The photoelectrocatalytic advanced oxidation-suspended filler biofilm reactor coupling system according to any one of claims 1 to 8 comprises the following steps: S1, Biofilm growth and bioacclimation on porous biofilm carriers: The sewage to be treated and the activated sludge are introduced into the biofilm tank to carry out the first aerobic reaction; then the porous biofilm carrier and coconut shell powder are added, and the sewage to be treated and the treated sewage are intermittently introduced to carry out the second aerobic reaction. After 5 to 10 days, the treated purified water is discharged; S2, introducing the wastewater to be treated into the electrolytic cell, adjusting the pH value of the wastewater to be treated to 2-7 and the conductivity to 250 μS / cm-1000 μS / cm, starting the photoelectrocatalytic advanced oxidation system, and performing photoelectrocatalytic treatment to obtain photoelectrocatalytic purified effluent; S3, introducing the photoelectric treatment purified water into a biofilm pool to perform a third aerobic reaction to obtain biofilm pool purified water; S4, returning the purified water from the biofilm pool to the electrolytic cell, and repeating steps S2 to S3 until purified water that meets discharge standards is obtained.

10. The method for treating sewage by coupling photoelectrocatalytic advanced oxidation and suspended filler biofilm reactor according to claim 9, characterized in that: In S1, the temperature of the first aerobic reaction is 20°C to 35°C, and the ventilation volume is 100m 3 / h~150m 3 / h, time is 30h~90h; and / or In S1, the temperature of the second aerobic reaction is 20°C to 35°C, the dissolved oxygen concentration is 3mg / L to 6mg / L, and the time is 7d to 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 COD of the sewage to be treated is 150mg / L~12000mg / L, the ammonia nitrogen value is 50mg / L~390mg / L, the BOD is 70mg / L~410mg / L, the suspended matter content is 100mg / L~190mg / L, and the heavy metal ion content is 10mg / L~180mg / 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°C to 35°C, the dissolved oxygen concentration is 3mg / L to 6mg / L, and the time is 12h to 48h.

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