Advanced oxidation treatment device and treatment method for printing and dyeing wastewater

Abstract

The invention discloses an advanced oxidation treatment device and treatment method for printing and dyeing wastewater, and relates to the technical field of sewage treatment.The device comprises a closed reactor, a feeding port is formed in the bottom of the closed reactor, and a discharging port and an exhaust port are formed in the top of the closed reactor; a functional filler layer is arranged in the closed reactor; activating balls and persulfate are arranged in the functional filler layer, the activating balls are formed by soaking Fe3O4 nano-particles and wine brewing wastewater fermentation liquor, and volatile fatty acid adsorbed on the surfaces of the activating balls is at pH gt; when the temperature is 7.5, the persulfate is desorbed and activated to generate sulfate free radicals. According to the invention, an autocatalysis system composed of pH responsive activation balls and persulfate is constructed in the functional filler layer, so that sulfate free radicals can be generated without adding an external agent, and meanwhile, the purpose of reducing carbon emission by inhibiting the activity of methanogens through metabolic competition is achieved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an advanced oxidation treatment device and method for dyeing and printing wastewater. Background Technology

[0002] In the practice of wastewater treatment engineering in the textile printing and dyeing industry, the mainstream technical approach known to those skilled in the art is a four-stage series combined process of "physicochemical pretreatment - anaerobic biological treatment - aerobic biological treatment - terminal advanced oxidation". Specifically, high-concentration printing and dyeing wastewater first undergoes coagulation and sedimentation unit with the addition of inorganic flocculants to remove suspended and colloidal pollutants; then it enters an upflow anaerobic sludge blanket (UASB) reactor for anaerobic digestion. Although this process can degrade some recalcitrant organic matter, it inevitably involves the generation and emission of a large amount of methane gas; subsequently, the wastewater flows sequentially through a hydrolysis acidification tank, an anaerobic tank, and an aerobic tank to complete biological denitrification and removal of residual organic matter; finally, hydrogen peroxide and ferrous salts are added in the Fenton oxidation unit for terminal chemical oxidation to ensure that the effluent meets the standards. The process layout has the following structural defects: each treatment unit is spatially independent and connected to the pipeline network via pumps, resulting in a significant footprint; the methanogenesis process in the UASB unit lacks effective means of suppression, resulting in only moderate carbon emission intensity; the Fenton oxidation unit requires continuous external addition of oxidants and catalysts, leading to high costs for reagents and iron-containing sludge disposal; the system fails to achieve closed-loop circulation of material flow and cascade utilization of energy during pollutant degradation, and each unit has a single function and lacks a synergistic effect mechanism.

[0003] While existing technologies can achieve compliant treatment of dyeing and printing wastewater, the endogenous driving force of the oxidation reaction and the metabolic regulation of carbon emissions cannot be synergistically achieved within the same reaction space. Specifically, traditional Fenton oxidation relies entirely on externally added ferrous ions and hydrogen peroxide; the system cannot utilize the Fe naturally dissolved from the upstream biological unit. 2+ The use of short-chain fatty acids produced by metabolism as activators results in reagent costs that are generally comparable to the yield of iron sludge. At the same time, the methanogenesis process in the anaerobic unit and the organic matter oxidation in the aerobic unit are independent of each other at the level of microbial metabolism. There is a lack of effective means to inhibit the activity of methanogens through electron competition or substrate-directed regulation, which means that carbon emission problems can only be addressed passively through end-of-pipe collection, and cannot be actively reduced at the level of reaction mechanism. Summary of the Invention

[0004] The purpose of this invention is to provide an advanced oxidation treatment device and method for dyeing and printing wastewater. By constructing a self-catalytic system composed of pH-responsive activation balls and persulfate within a functional packing layer, the invention addresses the technical problems of traditional advanced oxidation relying on external reagent addition and high carbon emissions from anaerobic treatment.

[0005] The present invention is achieved through the following technical solution: First, the present invention provides an advanced oxidation treatment device for dyeing and printing wastewater, including a closed reactor, with an inlet at the bottom of the closed reactor and an outlet and an exhaust port at the top of the closed reactor. The closed reactor is equipped with a functional packing layer, which is designed to guide the dyeing and printing wastewater into the inlet, and after being oxidized by the functional packing layer, it is discharged from the outlet. The functional packing layer contains activation balls and persulfate. The activation balls are made of Fe3O4 nanoparticles impregnated with brewing wastewater fermentation liquid. The volatile fatty acids adsorbed on the surface of the activation balls desorb when pH>7.5, activating the persulfate to generate sulfate free radicals.

[0006] As an optional implementation, the functional filler layer includes, from bottom to top, a primary micro-electrolysis peroxide layer, a secondary pH-responsive oxide layer, and a tertiary electron mediator buffer layer, with persulfate disposed within the secondary pH-responsive oxide layer.

[0007] As an optional implementation, the primary micro-electrolysis peroxide layer includes multiple primary particles, which are prepared from iron powder, activated carbon, kaolin and calcium peroxide in a mass ratio of (2~3):(0.4~0.6):2:(0.25~0.35), and the particle size of a single primary particle is 6~8 mm.

[0008] As an optional implementation, the secondary pH-responsive oxide layer includes multiple secondary particles, each of which includes a core particle and a shell. The core particle is prepared from iron powder, activated carbon, and kaolin in a mass ratio of (1~2):0.5:(1.5~2.5), and the shell includes modified biochar and calcium persulfate in a mass ratio of 0.8:(0.35~0.45). The particle size of the core particle is 6~8 mm, and the particle size of the secondary particles is 10~15 mm.

[0009] As an optional implementation, the tertiary electron mediator buffer layer comprises a plurality of tertiary particles, each of which is made of modified biochar loaded with sodium anthraquinone-2,6-disulfonate. The particle size of the tertiary particles is 4-6 mm, and the sodium anthraquinone-2,6-disulfonate loading is 0.04-0.06 mol / L.

[0010] As an optional implementation method, the modified biochar is prepared by pyrolyzing straw at 300~400℃ in anoxic conditions.

[0011] As an optional implementation, activation spheres with a volume ratio of 3-5% are provided in the primary micro-electrolysis peroxide layer, the secondary pH-responsive oxide layer, and the tertiary electron mediator buffer layer. The Fe3O4 nanoparticles have a particle size of 20~50nm. The impregnation mass ratio of Fe3O4 nanoparticles to brewing wastewater fermentation liquid is 1:(3~5), and the impregnation time is 12~18h.

[0012] As an optional implementation, a magnetic collection slope is provided at the bottom of the inner cavity of the closed reactor. The magnetic collection slope has a built-in permanent magnet array with a magnetic field strength of 0.1~0.3T, which is used to recover aged packing material. A water distribution plate is installed at the bottom of the primary micro-electrolysis peroxide layer.

[0013] Secondly, this invention also provides a method for advanced oxidation treatment of dyeing and printing wastewater, comprising the following steps: S1: Dyeing and printing wastewater with pH 5.5~6.5 enters the primary micro-electrolysis peroxide layer through the feed inlet and water distribution plate; S2: The dyeing and printing wastewater is flowed into the secondary pH-responsive oxidation layer, and the pH rises to 7.5~8.0; S3: The dyeing and printing wastewater flows into the three-stage electron mediator buffer layer; S4: After running for 30-40 days, shut off the water inlet, recover the aged packing from the magnetic inclined plane, and regenerate it by soaking it in hydrochloric acid solution.

[0014] As an optional implementation, the hydraulic retention time in S1 is 1.5~2.5h, dissolved oxygen is <0.3mg / L, calcium peroxide slowly releases H2O2, and Fe... 0 Dissolved Fe 2+ Formation of Fenton-like reactions; The residence time in S2 is 2.0~3.0h, during which calcium persulfate releases S2O8. 2- , by Fe 2+ Activation produces SO4•-; The residence time in S3 is 1.0~1.5h, Fe 3+ with Fe 2+ Cycle, SO4• - Continuous generation, SO4 2- Reducing bacteria compete with methanogens for substrates; The concentration of hydrochloric acid solution in S4 is 3~5wt%, and the soaking time is 1~2h.

[0015] Compared with the prior art, the embodiments of the present invention have the following advantages and beneficial effects: 1. In this embodiment of the invention, the endogenous utilization of anaerobic metabolites is coupled with the self-driven activation of advanced oxidation within a single reactor, achieving a closed-loop cycle of carbon-iron-sulfur elemental flow: Fe dissolved from the front-end anaerobic unit 2+The VFAs produced by metabolism enter the packing layer with the influent. Under the adsorption-desorption regulation of pH-responsive activation balls, they spontaneously release and activate persulfate in the locally slightly alkaline region (pH>7.5), generating highly active free radicals to oxidize and degrade residual recalcitrant organic matter (such as anthraquinones and azo dyes) in the dyeing and printing wastewater. At the same time, the consumption of VFAs changes the electron flow direction of anaerobic microorganisms, inhibiting the activity of methyl-CoM reductase in methanogens, thus reducing CH4 generation at the source. This device does not require external addition of ferrous salts and acid / alkali adjusters, reducing reagent costs and iron sludge production. By directionally regulating the microbial metabolic pathway, it reduces carbon emission intensity, ultimately achieving effluent COD <50 mg / L and color <80 times, realizing low-carbon, low-cost, and highly efficient synergistic treatment.

[0016] 2. In this embodiment of the invention, a three-level hierarchical structure is used to isolate functional space and couple reaction sequence to generate Fe through micro-electrolysis. 2+ The three processes of pH-responsive activation of persulfate, electron-medium deep oxidation, and other processes are directionally connected in series in the vertical direction, allowing each layer to focus on a specific function and avoid mutual interference. This design achieves a synergistic improvement in oxidant activation efficiency and pollutant removal rate: the micro-electrolysis layer pre-produces Fe... 2+ The pH-responsive layer provides an endogenous catalyst, avoiding external addition; it utilizes persulfate to ensure efficient oxidant release within the optimal pH range; and the electron mediator buffer layer extends the effective oxidation reaction time and stabilizes effluent quality by delaying free radical quenching and retaining suspended solids. This overall structure significantly enhances the system's resistance to shock loads, reduces unit oxidant consumption, decreases iron sludge production, and improves the stability of effluent quality.

[0017] 3. This invention achieves online recovery and dynamic balance of iron elements in the activated spheres through a gradient magnetic field and gravity-assisted enrichment mechanism: when the magnetization intensity of the aged activated spheres decays to 30~40 emu / g, the inclined magnetic field directionally separates them from the bottom of the packing layer, with a recovery rate >85%. After re-impregnation with brewing waste liquid, the reuse rate reaches over 90%, and the amount of iron supplementation in the system is reduced. The water distribution plate dissipates the kinetic energy of the incoming water through orifice homogenization and damping flow stabilization, allowing the water to flow evenly into the primary micro-electrolysis layer, improving micro-electrolysis efficiency, and extending the continuous operation cycle from 90 days to 180 days. The PTFE lining on the inclined surface prevents iron sludge adhesion and corrosion, and the bottom slag discharge pipe periodically discharges broken particles. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the advanced oxidation treatment apparatus provided in an embodiment of the present invention.

[0020] The attached diagram shows the markings and corresponding component names: A closed reactor, 2-inlet, 3-outlet, 4-exhaust port; 5-Functional filler layer, 6-Primary micro-electrolysis peroxide layer, 7-Secondary pH-responsive oxide layer, 8-Tertiary electron mediator buffer layer; 9-Magnetic collecting slope, 10-Water distribution plate. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that the terms "first," "second," "third," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Example

[0025] Example 1: This embodiment of the invention provides an advanced oxidation treatment device for dyeing and printing wastewater, referring to... Figure 1As shown, the reactor includes a closed reactor 1, with an inlet 2 at the bottom and an outlet 3 and an exhaust port 4 at the top. A functional packing layer 5 is installed inside the closed reactor 1. This layer guides the dyeing and printing wastewater into the reactor through the inlet 2, and after oxidation treatment by the packing layer 5, it is discharged through the outlet 3. The packing layer 5 contains activation balls and persulfate. The activation balls are made by impregnating Fe3O4 nanoparticles with fermentation liquid from brewing wastewater. Volatile fatty acids adsorbed on the surface of the activation balls desorb when pH > 7.5, activating the persulfate to generate sulfate free radicals.

[0026] Exemplarily, in this embodiment of the invention, the closed reactor 1 is a vertical pressure vessel with a feed pipe tangentially connected to its bottom sidewall. The feed inlet 2 is sealed to the effluent pumping pipeline of the upstream anaerobic treatment unit (such as a hydrolysis acidification tank) via a flange, ensuring that the anaerobic effluent containing dissolved iron ions and volatile fatty acids (VFAs) is directly introduced into the reactor under anaerobic / micro-aerobic conditions. A discharge port 3 is vertically positioned at the center of the reactor top, connected to a subsequent neutralization sedimentation tank or advanced treatment unit via a solenoid valve, enabling controlled discharge of the oxidized wastewater. An exhaust port 4 is located on the top sidewall, connected to a micro-negative pressure gas collection system via a gas check valve, used to collect and remove trace amounts of CO2 or residual gas generated during the reaction. This arrangement utilizes the reactor's height-to-diameter ratio to create a plug-flow water pattern, avoiding short-circuiting and back-mixing.

[0027] The functional packing layer 5 fills the main space in the middle of the closed reactor 1, occupying 60-75% of the effective volume of the reactor. It consists of a porous inert carrier (such as ceramsite or volcanic rock) with a particle size of 3-5 mm, forming the bed framework. Inside the bed, activation balls and persulfate solid particles (sodium persulfate or potassium persulfate) are uniformly mixed at a volume ratio of 1:5 to 1:8 to form a reaction zone. The bottom of the packing layer is supported by a perforated water distribution plate 10. The water distribution plate 10 has an opening rate of 15-20% and a pore size of 2-3 mm to ensure uniform water distribution and prevent packing leakage. A stainless steel wire mesh cap (1-2 mm mesh) is installed at the top of the packing layer to limit packing expansion and maintain bed stability, while allowing the oxidized wastewater to flow smoothly into the top effluent zone. pH online monitoring probes are installed at 0.5 m intervals along the height direction inside the bed to provide real-time feedback on pH changes and regulate the influent water quality.

[0028] The activation sphere has a core-shell structure, with the core being an aggregate of Fe3O4 nanomagnetic particles and the outer shell being a biochar-based porous layer formed by impregnation with brewing wastewater fermentation broth. This structure achieves synergistic activation through the following principle: (1) VFAs such as acetic acid, propionic acid, and butyric acid in brewing waste liquid are adsorbed and concentrated by the biochar layer under anaerobic conditions. When pH>7.5, VFAs are desorbed and released into the liquid phase. (2) Fe on the surface of the Fe3O4 core 2+with Fe 3+ Cyclic conversion, desorbed VFAs act as organic ligands to promote Fe 2+ Dissolves and stabilizes its form; (3) Dissolved Fe 2+ With persulfate (S2O8) 2- A homogeneous reaction occurs within the pores of the packing material, generating SO4. - · and ·OH, and the Fe3O4 surface can also directly catalyze the heterogeneous activation of persulfate.

[0029] The closed reactor 1 utilizes an upflow design with bottom inlet and top outlet to create a stable plug flow pattern, maximizing pollutant degradation efficiency. Anaerobic sludge flocs or dissolved microbial products carried by the influent are retained by the packing layer, serving as a supplementary carbon source for VFAs regeneration. A jacketed heat exchanger is installed on the reactor's outer wall to maintain the reaction temperature at 35-40°C, thereby increasing the persulfate activation rate. Magnetic activation balls can be periodically recovered and regenerated via a magnetic ramp at the bottom of the reactor. The recovered activation balls are then re-impregnated with the brewing wastewater fermentation broth and recycled, achieving a closed-loop cycle for the functional materials.

[0030] In a preferred embodiment of the present invention, the functional packing layer 5 comprises, from bottom to top, a primary micro-electrolysis peroxide layer 6, a secondary pH-responsive oxidation layer 7, and a tertiary electron mediator buffer layer 8. Persulfate is disposed within the secondary pH-responsive oxidation layer 7. These three layers together constitute the core treatment unit within the closed reactor 1. Wastewater enters from the bottom inlet 2 and flows sequentially through the three functional layers to complete sequential oxidation treatment, finally discharging from the top outlet 3. Adjacent layers are separated by physical interfaces to prevent packing material mixing and ensure the directionality of water flow and mass transfer.

[0031] The first-level micro-electrolysis peroxidation layer 6 is located at the bottom and directly receives the influent. It uses micro-electrolysis to pre-oxidize the wastewater and provide reducing iron ions to the upper layer. The second-level pH-responsive oxidation layer 7 is located in the middle layer and is the persulfate addition layer. This layer contains activation spheres and solid persulfate. When the pH value of the wastewater increases due to the reaction in the lower layer, the volatile fatty acids adsorbed on the surface of the activation spheres desorb and work with iron ions to activate the persulfate to generate sulfate free radicals, completing the main oxidation reaction. The third-level electron mediator buffer layer 8 is located at the top layer. It deeply oxidizes residual pollutants through electron mediator action and buffers water quality fluctuations to ensure the stability of the effluent. The material flow between the layers is achieved through water phase dissolution and pore diffusion to achieve vertical transfer.

[0032] In this embodiment of the invention, preferably, the primary micro-electrolysis peroxide layer 6 comprises a plurality of primary particles, which are prepared from iron powder, activated carbon, kaolin and calcium peroxide in a mass ratio of (2~3):(0.4~0.6):2:(0.25~0.35), and the particle size of a single primary particle is 6~8mm.

[0033] Specifically, the raw material mass ratio of each primary particle is iron powder: activated carbon: kaolin: calcium peroxide = (2~3):(0.4~0.6):2:(0.25~0.35). This ratio can balance reactivity and structural stability. When the iron powder content reaches 2~3 parts, a dense Fe-C micro galvanic cell network can be formed inside the particle, ensuring Fe... 2+ Sufficient dissolution is required to drive subsequent persulfate activation. If the amount is less than 2 parts, the number of galvanic cells will be insufficient, and the amount of dissolved iron will be insufficient to meet the requirements of two-stage oxidation. However, if the amount is more than 3 parts, excessive iron powder will lead to excessive shrinkage during particle calcination, collapse of the pore structure, and excessive corrosion will generate too much iron oxide to block the pores of the particles. Activated carbon should be controlled at 0.4~0.6 parts to ensure sufficient cathode potential and an intact conductive network, avoiding limited micro-electrolysis efficiency when the proportion is too low, and preventing excessive retention of VFAs due to strong adsorption when the proportion is too high, which would affect their mass transfer and release to the pH-responsive layer. Kaolin is used as a binder. This amount allows the particles to obtain a compressive strength of ≥15 N / particle after calcination at 350~400℃. Insufficient amount will lead to brittle particles and bed collapse, while excessive amount will excessively coat the surface of the iron powder and hinder the exposure of micro-electrolysis reaction sites. A dosage of 0.25–0.35 parts of calcium peroxide allows for the sustained release of H2O2 after the particles are wetted (hydrolysis half-life approximately 8–12 hours). Too low a dosage results in a weak localized Fenton-like effect, contributing insufficiently to the pre-oxidation of dye molecules. Too high a dosage causes a sudden release of large amounts of Ca(OH)2 and H2O2, leading to a localized pH spike above 8.5, which inhibits the micro-electrolysis reaction and generates microbubbles that interfere with water flow uniformity. The final particle size is controlled at 6–8 mm. This size balances bed porosity (45–55%) and hydraulic flow. Smaller particle sizes (<6 mm) increase the specific surface area but lead to a significant increase in head loss and make backwashing difficult, easily causing clogging. Larger particle sizes (>8 mm) result in excessively long internal mass transfer paths and reduced utilization of the iron powder core, leading to increased Fe content within the particles. 2+ Dissolution lags, resulting in a time-space mismatch with VFAs release.

[0034] This granular formulation achieves self-supply of endogenous oxidants and catalysts through a micro-electrolysis-peroxidation synergistic mechanism: the iron-carbon micro-galvanic cell dissolves Fe under influent pH conditions of 5.5~6.5. 2+ It also releases nascent hydrogen (H), and calcium peroxide slowly releases H2O2 and Fe. 2+ A localized Fenton-like system forms on the particle surface, generating ·OH to achieve pre-oxidative chain scission of dye molecules. This layer itself can achieve a COD removal rate of 15-20% and a color removal rate of 25-35%, while providing stable Fe for persulfate activation. 2+Compared to traditional iron-carbon fillers, the introduction of calcium peroxide increases the redox potential of this layer by 200~300 mV, thereby improving the ring-opening efficiency of the azo bond and anthraquinone structure.

[0035] Preferably, the secondary pH-responsive oxide layer 7 comprises multiple secondary particles, each of which includes a core particle and a shell. The core particle is prepared from iron powder, activated carbon, and kaolin in a mass ratio of (1~2):0.5:(1.5~2.5). The shell comprises modified biochar and calcium persulfate in a mass ratio of 0.8:(0.35~0.45). The particle size of the core particle is 6~8 mm, and the particle size of the secondary particles is 10~15 mm.

[0036] Specifically, each secondary particle has a core of micro-electrolysis matrix and an outer shell of persulfate-supported layer. The mass ratio of the core particle raw materials is iron powder: activated carbon: kaolin = (1~2):0.5:(1.5~2.5), with the iron powder content reduced to 1~2 parts to ensure that the core maintains the necessary Fe content. 2+ The slow-release capability continuously drives persulfate activation while avoiding excessive iron powder content that could cause the core to crack due to excessive internal stress during calcination caused by the iron oxide phase transformation; if the iron powder content is less than 1 part, the Fe generated in the core... 2+ Insufficient flux cannot match the iron ion requirements of the upper electron mediator buffer layer. Activated carbon, as the conductive network framework, suffers from several drawbacks: too low a proportion leads to a sharp decrease in the number of micro-galvanic cells, reduced electron transfer efficiency, and impaired core-level regulation of the local pH microenvironment; while too high a proportion results in excessive trapping of Fe dissolved from the core due to its strong adsorption properties. 2+ This leads to Fe 2+It is difficult for VFAs to migrate to the outer shell. The amount of kaolin used is 1.5 to 2.5 parts. This range can meet the strength requirements after the core particle size increases to 6 to 8 mm. If the amount is insufficient, the mechanical strength of the core will decrease at the 6 to 8 mm scale, and the bed will easily pulverize after being subjected to pressure. If the amount is too large, the binder phase will be over-sintered, the porosity will be compressed, and the mass transfer and diffusion of VFAs from the core to the outer shell will be hindered. The outer shell is coated with a mixture of modified biochar and calcium persulfate in a ratio of 0.8:(0.35~0.45). The biochar accounts for 0.8 parts and forms the main framework of the outer shell. Its abundant carboxyl and phenolic hydroxyl functional groups endow it with pH-responsive adsorption capacity. If the proportion of biochar is reduced, the adsorption capacity of the outer shell for VFAs will be insufficient, making it difficult to trigger sufficient desorption to activate calcium persulfate when pH>7.5. The calcium persulfate is controlled at 0.35~0.45 parts. This loading can maintain the effective concentration of persulfate in the outer shell at 8~12 wt%. This ensures that the secondary pH-responsive oxidation layer 7, as the core reaction zone, has sufficient oxidation equivalent, while avoiding the loss of calcium persulfate due to saturation of the outer shell pores if the loading is too high, or the oxidation capacity is insufficient to bear the pollutant load after the pre-oxidation of the primary layer if the loading is too low. The final total particle size of the secondary particles is 10-15 mm. Within this size range, the outer shell thickness is 2-7 mm. If the outer shell is too thin (<2 mm), the calcium persulfate loading is limited, and the modified biochar layer cannot form a complete pH response gradient; if the outer shell is too thick (>7 mm), Fe dissolves from the core... 2+ If the required diffusion distance is too long, the spatiotemporal matching with the desorbed VFAs in the shell will be misaligned, resulting in a decrease in activation efficiency.

[0037] The core-shell structure of secondary particles achieves pH-responsive precision oxidation through spatial functional separation and interfacial reaction synergy: continuous dissolution of Fe from the core microelectrolysis. 2+ It maintains a locally weakly acidic microenvironment, and the shell-modified biochar adsorbs VFAs and desorbs them at pH > 7.5. The desorbed VFAs react with Fe that diffuses into the shell. 2+ Calcium persulfate is activated together to produce SO4. - • and •OH. This design concentrates the oxidation reaction mainly within the outer shell layer, preventing the core from being excessively oxidized and passivated. At the same time, the buffer thickness of the outer shell ensures that the oxidant release period reaches 8-10 hours, improving the utilization rate of the oxidant, and contributing 55-65% to COD removal and 70-80% to color removal.

[0038] Preferably, the tertiary electron mediator buffer layer 8 comprises multiple tertiary particles, each of which is made of modified biochar loaded with anthraquinone-2,6-disulfonate. The particle size of the tertiary particles is 4-6 mm, and the loading of anthraquinone-2,6-disulfonate is 0.04-0.06 mol / L. The modified biochar is obtained by anaerobic pyrolysis of straw at 300-400℃.

[0039] Specifically, the particle size of a single tertiary particle is 4-6 mm, and the AQDS loading is 0.04-0.06 mol / L. If the particle size is less than 4 mm, the bed porosity will be compressed, leading to a sharp increase in head loss, and it is easy to trap iron oxide particles detached from the previous two layers, causing caking and blockage. If the particle size is greater than 6 mm, the diffusion path within the particles will be too long, the interfacial electron transfer rate between the AQDS mediator and pollutant molecules will be reduced, and the insufficient bed packing density will cause the total mediator volume to decrease, thus reducing the treatment capacity.

[0040] If the loading is below 0.04 mol / L: Insufficient AQDS concentration leads to a low redox cycle frequency, resulting in insufficient indirect oxidation contribution to the degradation intermediates of residual polycyclic aromatic hydrocarbons in the secondary effluent, and the final COD removal rate cannot exceed 85%; If it is above 0.06 mol / L: Excessive AQDS is prone to crystallization and aggregation in the micropores of biochar, which reduces the effective active sites, and the risk of leaching will cause secondary pollution and increase operating costs.

[0041] More preferably, after anaerobic pyrolysis, the straw raw material is further modified by combined oxidative treatment with nitric acid and hydrogen peroxide (nitric acid concentration 2 mol / L, H2O2 concentration 15%, modification at 90℃ for 3 h), increasing the content of surface carboxyl and phenolic hydroxyl groups to 2.5~3.0 meq / g. The loading process adopts vacuum-pressure cyclic impregnation: the modified biochar is first placed in a 0.5 mol / L AQDS solution for vacuum impregnation for 2 h (vacuum degree ~0.08 MPa), then pressurized at 0.2 MPa for 4 h, and finally vacuum dried at 105℃ to constant weight, ensuring that AQDS is anchored in the pores of biochar through π-π stacking and hydrogen bonding, with a loading uniformity CV <5%.

[0042] In this embodiment of the invention, the tertiary particles serve as the terminal deep oxidation unit, working synergistically through an electron mediator cycling mechanism and a free radical buffering mechanism: AQDS forms redox active centers on the surface of straw-based modified biochar, and its anthraquinone groups reversibly capture and transfer electrons, deeply oxidizing the recalcitrant intermediates (such as benzoquinones and hydroxybiphenyls) that were not fully mineralized in the secondary pH-responsive oxidation layer 7 through a non-free radical indirect electron transfer pathway, while simultaneously removing excess SO4. - • ·OH free radicals are quenched on the mediator surface and converted into H2O and O2, avoiding the ineffective consumption of free radicals. This layer can also retain iron ions lost from the previous secondary layer (effluent Fe < 0.3 mg / L) and some Fe 3+ Reduced to Fe 2+ The effluent is returned to the secondary pH-responsive oxidation layer 7 to construct a micro-circulation system for iron. This design increases the overall COD removal rate to 85-90%, the color removal rate to >95%, and reduces the production of end-of-pipe sludge. The effluent ORP is stabilized at +180~+220 mV, ensuring water quality stability.

[0043] In a preferred embodiment of the present invention, activation spheres with a volume ratio of 3-5% are provided in the primary micro-electrolysis peroxide layer 6, the secondary pH-responsive oxide layer 7, and the tertiary electron mediator buffer layer 8; the particle size of Fe3O4 nanoparticles is 20-50 nm, the impregnation mass ratio of Fe3O4 nanoparticles to brewing wastewater fermentation liquid is 1:(3-5), and the impregnation time is 12-18 h.

[0044] When the particle size is too small (e.g., <20 nm), the surface energy of the nanoparticles is too high, making them prone to magnetic aggregation during impregnation and reaction. This results in poor dispersibility in the brewing waste liquid, a sharp reduction in the effective specific surface area, and weakened superparamagnetism, leading to a decrease in subsequent magnetic separation recovery. Simultaneously, excessively small nanoparticles easily penetrate the pores of the biochar shell and are lost, causing uneven distribution of iron between the three-stage packing layers. If the fermentation broth ratio is too low (e.g., <3 parts), the loading of VFAs (acetic acid, propionic acid, butyric acid) is insufficient, reducing the sensitivity of the activation spheres to pH response and shifting the desorption threshold to pH > 8.5. This prevents effective release of VFAs within the designed pH range of 7.5–8.0 for the secondary pH-responsive oxidation layer 7, reducing persulfate activation efficiency. If the impregnation time is insufficient, the brewing waste liquid only penetrates to the shallow layer of the shell, and the VFA adsorption capacity does not reach 70% of the saturation capacity. This causes the activation spheres to rapidly deplete the surface-adsorbed organic matter in the early stages of operation, losing their pH response regulation ability and requiring frequent regeneration.

[0045] When the particle size is >50 nm, the specific surface area is <40 m². 2 / g, insufficient density of surface active sites, dissolved Fe 2+ Reduced flux makes it difficult to form an effective iron microcirculation between the three layers; and large particles settle quickly, easily depositing at the bottom of the packing layer, making it impossible to achieve a uniform distribution at a volume ratio of 3-5%. If the proportion of fermentation broth is too high (e.g., >5 parts), the solid content of Fe3O4 nanoparticles in the suspension is too low, resulting in a loading of less than 8 wt% on the biochar support, leading to a decline in both magnetic and catalytic performance. Simultaneously, excessive organic matter easily forms a dense organic film on the particle surface during the drying process after impregnation, hindering the desorption and release of VFAs during the reaction. If the impregnation time is too long, the residual microorganisms in the brewing waste liquid will over-proliferate, causing rancidity and producing byproducts such as sulfides that poison the Fe3O4 surface. Furthermore, the loss rate of VFAs due to microbial degradation increases, thus reducing the effective loading.

[0046] If the number of activated spheres is insufficient, and the spacing between activated spheres in the three-stage packing layer is >15 mm, it will be difficult to form an effective Fe... 2+Compared with the VFAs concentration field network, the improvement in oxidant utilization is small, and its contribution to overall COD removal is minimal. If the activation balls are added in excess to >5%, they will crowd out the space of the main packing materials (micro-electrolytic particles, persulfate, and electron mediators) in each layer, resulting in a decrease in the loading of functional materials within the layer. Furthermore, the close proximity of the activation balls leads to competitive adsorption of VFAs, causing local desorption concentration imbalances and reducing the accuracy of pH response.

[0047] Activation spheres, acting as intelligent response nodes in the three-tiered packing layer, form a sparse yet uniformly distributed network of activation sites in each layer at an optimized volume ratio of 3–5%. 20–50 nm Fe3O4 provides a high active specific surface area (50–80 nm). 2 With strong magnetic responsiveness (saturation magnetization >60 emu / g), it is easy to recover; the impregnation ratio of 1:(3~5) and the impregnation time of 12~18 h synergistically ensure that the VFAs loading is stable at 18~22 wt%, and is gradient-distributed within the shell thickness of 0.2~0.3 mm, achieving rapid desorption at pH>7.5 (desorption rate >75% within 15 minutes). This parameter combination enables the activation ball to assist in the supplementation of Fe in the micro-electrolysis layer. 2+ The system dominates persulfate activation in the pH-responsive layer and finely adjusts iron reflux in the electron mediator layer. Under the three-stage synergy, the overall utilization rate of oxidant is improved to 75-78%, the system's resistance to shock loads is enhanced, the production of iron sludge is reduced, and intelligent control of endogenous carbon and iron circulation is achieved.

[0048] Furthermore, a magnetic collection slope 9 is provided at the bottom of the inner cavity of the sealed reactor 1. The magnetic collection slope 9 has a built-in permanent magnet array with a magnetic field strength of 0.1~0.3T, which is used to recover aged packing material; a water distribution plate 10 is provided at the bottom of the primary micro-electrolysis peroxide layer 6.

[0049] For example, a magnetic collection ramp 9 with an inclination angle of 15-20° is set at the bottom of the closed reactor 1, with a permanent magnet array containing a magnetic field strength of 0.1-0.3 T. A titanium alloy water distribution plate 10 is set at the bottom of the primary micro-electrolysis peroxide layer 6, with a distance of 50-80 mm between the two to form a pre-sedimentation buffer zone. This structure achieves online recovery of activation balls and dynamic balance of iron elements through a gradient magnetic field and gravity-assisted enrichment mechanism: when the magnetization intensity of the aged activation balls decays to 30-40 emu / g, the inclined magnetic field separates them directionally from the bottom of the packing layer, with a recovery rate of >85%. After re-impregnation with brewing waste liquid, the reuse rate reaches over 90%, and the amount of iron element supplemented in the system is reduced. The water distribution plate 10 dissipates the kinetic energy of the incoming water through orifice homogenization and damping flow stabilization, so that the water flows evenly into the primary micro-electrolysis layer, improving the micro-electrolysis efficiency and extending the continuous operation cycle from 90 days to 180 days. The PTFE lining on the inclined surface prevents iron sludge adhesion and corrosion, and the bottom slag discharge pipe periodically discharges broken particles.

[0050] Example 2: Another embodiment of the invention provides a method for advanced oxidation treatment of dyeing and printing wastewater, comprising the following steps: S1: Dyeing and printing wastewater (COD 1200~1400mg / L, color 2000~3000 times, pH 5.5~6.5) enters the primary zone through distribution plate 10, with a hydraulic retention time of 1.5~2.5h and dissolved oxygen <0.3mg / L. Calcium peroxide slowly releases H2O2 (8~12mg / L), Fe... 0 Dissolved Fe 2+ (20~30mg / L) Forms a Fenton-like reaction, with a COD removal rate of 15~25%.

[0051] S2: Wastewater flows into the secondary zone, pH rises to 7.5-8.0, and remains for 2.0-3.0 hours. Calcium persulfate rapidly releases S2O8. 2- (30~45mg / L), by Fe 2+ Activation produces SO4· - (25~40mg / L), azo dyes and anilines, removal rate >70%.

[0052] S3: Wastewater enters the tertiary zone and remains for 1.0~1.5 hours. Quinone mediators accelerate Fe... 3+ / Fe 2+ Cycle, SO4· - Continuous generation; simultaneously SO4 2- Reducing bacteria compete with methanogens for substrates, reducing CH4 emissions to 5.5–7.0 g / m³. 2 ·d (60-65% lower than traditional processes).

[0053] S4: After running for 30-40 days, shut off the water inlet and recover 30-40% of the aged packing from the magnetic inclined surface. Regenerate the packing by soaking it in 3-5% dilute hydrochloric acid for 1-2 hours.

[0054] Specifically, under weakly acidic micro-oxygen conditions (pH 6.0–6.5, dissolved oxygen <0.3 mg / L), S1 dissolves Fe through iron-carbon micro-electrolysis. 2+ (20~30 mg / L) reacts with calcium peroxide to release H2O2 (8~12 mg / L) to form an endogenous Fenton-like reaction, achieving a rapid COD reduction of 15~25% for easily broken esters and long-chain alkanes in dyeing and printing wastewater, while simultaneously dissolving Fe. 2+ As a precursor catalyst for the secondary reaction, S2, through the alkali-producing effect of primary micro-electrolysis and the self-buffering effect of calcium persulfate hydrolysis, precisely raises the pH to 7.5-8.0. This window value precisely triggers the desorption of VFAs on the surface of the activated sphere and the diffusion of Fe to the secondary reaction. 2+ Synergistic activation of S2O8 released by calcium persulfate 2- (30~45 mg / L), producing SO4·- (25~40 mg / L) Targeted attack on azo dyes and aniline pollutants, with a removal rate >80%. This pH threshold design bypasses the optimal pH range for methanogens (6.8~7.2), laying the foundation for subsequent carbon emission reduction; S3 introduces anthraquinone mediators to accelerate Fe 3+ / Fe 2+ Circulation (cycle frequency > 50 times / h) not only maintains SO4· - Continuous generation, and more importantly, creating a metabolically competitive environment between sulfate-reducing bacteria and methanogens, utilizing SO42- 2- As an electron acceptor, it preferentially consumes methanogenic substrates such as acetic acid and H2, reducing CH4 emissions to 5.5–7.0 g / m³. 2 ·d, compared with the traditional passive collection process, emissions are reduced by 60-65%, achieving active metabolic regulation of carbon emissions; S4 is set with a 30-40 day operating cycle. When the VFAs loading of the activation ball decays to <40% and the calcium persulfate consumption is >70%, 30-40% of the aged packing (magnetization intensity <10 emu / g) is recovered from the magnetic inclined surface. The surface iron oxide coating is dissolved by short soaking in 3-5% dilute hydrochloric acid (1-2 h) and the Fe3O4 core activity is restored. After regeneration, the magnetization intensity is >55 emu / g. The performance decay is <8% after 5 reuses, and the total iron loss is <5%. Compared with the traditional Fenton process, the reagent cost is reduced by 70%, the iron sludge production is reduced by 90%, and the overall system operating cost is reduced by 1.2 yuan / ton of water. The effluent COD is stable at <50 mg / L (removal rate 96-97.5%), the color is <80 times (>96%), and the ORP is controlled at +180~+220. mV, achieving a triple synergy of oxidant autocatalysis, active carbon emission reduction, and closed-loop material regeneration.

[0055] Example 3: This embodiment of the invention also provides an advanced oxidation treatment device and method for dyeing and printing wastewater, including the following: An advanced oxidation treatment device for dyeing and printing wastewater includes a closed vertical reactor with an inner diameter of 2.0 m, a total height of 5.5 m, and an effective volume of 15 m³. 3The reactor is made of 316L stainless steel. A DN100 feed inlet 2 is tangentially located at the bottom of the reactor, and a DN80 discharge outlet 3 with a solenoid valve is located at the center of the top. A DN50 exhaust port 4 is located on the top sidewall, connected to a micro-negative pressure gas collection system. The bottom of the inner cavity features a conical magnetic collection ramp 9 with an 18° inclination angle, housing a neodymium iron boron permanent magnet Halbach array with a surface magnetic field strength of 0.2 T. The ramp is lined with a 2 mm PTFE anti-corrosion layer, and the bottom is connected to a DN50 slag discharge pipe. A titanium alloy water distribution plate 10, 8 mm thick, with an 18% opening ratio and 2.5 mm diameter orifices arranged in staggered equilateral triangles, extends downwards by 2 mm. Above the water distribution plate 10, a three-stage functional filler layer 5 and a primary micro-electrolysis peroxide layer 6 are sequentially filled, with a height of 1.5 m. The filler consists of spherical particles with a particle size of 7 mm, and the raw material mass ratio is iron powder: activated carbon: kaolin: calcium peroxide = 2.5:0.5:2:0.3, with a filling density of 850 kg / m³. 3 The secondary pH-responsive oxide layer 7 has a height of 2.2 m, filled with core-shell structured particles. The core particle size is 7 mm (iron powder: activated carbon: kaolin = 1.5:0.5:2.0), the outer shell thickness is 3 mm (modified biochar: calcium persulfate = 0.8:0.4), the total particle size is 13 mm, and the packing density is 720 kg / m³. 3 The tertiary electron mediator buffer layer has a height of 1.0 m and is filled with straw-based modified biochar particles with a particle size of 5 mm. The AQDS loading is 0.05 mol / L, and the packing density is 650 kg / m³. 3 The packing layers are separated by PTFE perforated partitions with a porosity of 25%. Activation spheres, comprising 4% of the volume, are evenly distributed in each layer. These spheres are prepared by impregnating 35 nm Fe3O4 nanoparticles with brewing wastewater fermentation broth at a mass ratio of 1:4 for 15 h. A jacketed heat exchanger is installed on the outer wall of the reactor to maintain a temperature of 38±2℃, and pH online monitoring probes are installed every 0.5 m along the height.

[0056] The specific steps for treating dyeing and printing wastewater using the above-mentioned device are as follows: S1: Influent water quality: COD 1300 mg / L, color 2500 times, pH 6.0. After being evenly distributed by water distribution plate 10, it enters the primary micro-electrolysis peroxide layer 6, with a hydraulic retention time of 2.0 h and dissolved oxygen controlled at 0.2 mg / L. Within this layer, the concentration of H2O2 released by the hydrolysis of calcium peroxide reaches 10 mg / L, and Fe... 0 Micro-electrolysis to dissolve Fe 2+ At a concentration of 25 mg / L, a Fenton-like reaction was formed, resulting in a COD removal rate of 20%, a color removal rate of 30%, a B / C ratio increase from 0.18 to 0.32, and an effluent pH increase to 6.8.

[0057] S2: Wastewater enters the secondary pH-responsive oxidation layer 7, where the pH further rises to 7.8 due to the alkali production effect of micro-electrolysis, remaining for 2.5 hours. Calcium persulfate rapidly releases S2O8. 2- Concentration 38 mg / L, by Fe 2+ Activation produces SO4· - At a concentration of 32 mg / L, the removal rate of azo dyes and characteristic pollutants of aniline reached 75%, COD was removed by 520 mg / L, and the COD of the effluent was reduced to 520 mg / L.

[0058] S3: Wastewater enters the tertiary electron mediator buffer layer 8 and remains for 1.2 h. AQDS mediator accelerates Fe... 3+ / Fe 2+ The circulation frequency is increased to 50-60 times / hour to maintain SO4· - Continuous generation at a concentration of 15 mg / L, deep oxidation of residual polycyclic aromatic hydrocarbon intermediates; simultaneously SO4 2- As an electron acceptor, it promotes the dominant growth of sulfate-reducing bacteria, competing with methanogens for substrates, and reduces CH4 emissions to 6.2 g / m³. 2 ·d, reducing emissions by 62% compared to traditional passive end-of-pipe collection processes. The effluent from this layer has a COD of 52 mg / L, a color 18 times higher, an ORP stable at +210 mV, and a turbidity of <5 NTU.

[0059] S4: After 35 days of continuous operation, the inlet valve was closed, and 35% of the aged packing (whose magnetization intensity had decayed to 8 emu / g) was recovered from the magnetic collection slope 9. After soaking in 4% dilute hydrochloric acid for 1.5 h to dissolve the Fe2O3 and CaCO3 coating layer on the surface, the reload of the activated ball VFAs was restored to 19 wt%, the calcium persulfate regeneration rate was 85%, the magnetization intensity was restored to 58 emu / g, and the reuse rate reached 90%.

[0060] Technical Results: When the device and method are operated in tandem, the cost of the treatment agent per ton of water is reduced by RMB 1.15 compared to the traditional Fenton process, the iron sludge production is reduced by 92%, and the effluent consistently achieves COD <50 mg / L, color <20 times, Fe <0.3 mg / L, and aniline <0.3 mg / L (>95%). Through metabolic competition by sulfate-reducing bacteria, CH4 emissions are actively reduced by 62%, and carbon emission intensity is reduced by 45-60%. After 180 days of continuous operation, the performance of the packing material decreases by less than 8% after 5 reuses, achieving a triple synergy of oxidant autocatalysis, carbon emission reduction, and material regeneration.

[0061] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the scope of protection of the invention. It should be noted that the structures or components illustrated in the accompanying drawings are not necessarily drawn to scale, and descriptions of well-known components, processing techniques, and processes have been omitted to avoid unnecessarily limiting the invention.

Claims

1. An advanced oxidation treatment device for dyeing and printing wastewater, characterized in that, It includes a closed reactor (1), with a feed inlet (2) at the bottom and a discharge outlet (3) and an exhaust outlet (4) at the top. The closed reactor (1) is equipped with a functional packing layer (5). The functional packing layer (5) is designed to guide the dyeing and printing wastewater to enter from the inlet (2), and after being oxidized by the functional packing layer (5), it is discharged from the outlet (3). The functional filler layer (5) contains activation balls and persulfate. The activation balls are made by impregnating Fe3O4 nanoparticles with fermentation liquid from brewing wastewater. The volatile fatty acids adsorbed on the surface of the activation balls desorb when pH>7.5, and activate the persulfate to generate sulfate free radicals.

2. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 1, characterized in that, The functional filler layer (5) includes, from bottom to top, a primary micro-electrolysis peroxide layer (6), a secondary pH-responsive oxide layer (7), and a tertiary electron mediator buffer layer (8), with the persulfate disposed within the secondary pH-responsive oxide layer (7).

3. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 2, characterized in that, The primary micro-electrolysis peroxide layer (6) comprises multiple primary particles, which are prepared from iron powder, activated carbon, kaolin and calcium peroxide in a mass ratio of (2~3):(0.4~0.6):2:(0.25~0.35), and the particle size of a single primary particle is 6~8 mm.

4. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 2, characterized in that, The secondary pH-responsive oxide layer (7) includes multiple secondary particles, each of which includes a core particle and a shell. The core particle is prepared from iron powder, activated carbon and kaolin in a mass ratio of (1~2):0.5:(1.5~2.5). The shell includes modified biochar and calcium persulfate in a mass ratio of 0.8:(0.35~0.45). The particle size of the core particle is 6~8 mm, and the particle size of the secondary particles is 10~15 mm.

5. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 4, characterized in that, The tertiary electron mediator buffer layer (8) comprises multiple tertiary particles, each of which is made of modified biochar loaded with sodium anthraquinone-2,6-disulfonate. The particle size of the tertiary particles is 4-6 mm, and the sodium anthraquinone-2,6-disulfonate loading is 0.04-0.06 mol / L.

6. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 5, characterized in that, The modified biochar was obtained by pyrolyzing straw at 300-400℃ in anoxic conditions.

7. The advanced oxidation treatment device for dyeing and printing wastewater according to any one of claims 2 to 6, characterized in that, The primary micro-electrolysis peroxide layer (6), the secondary pH-responsive oxide layer (7), and the tertiary electron mediator buffer layer (8) are all provided with activation spheres at a volume ratio of 3-5%. The Fe3O4 nanoparticles have a particle size of 20-50 nm, and the impregnation mass ratio of the Fe3O4 nanoparticles to the fermentation liquid of brewing wastewater is 1:(3-5), with an impregnation time of 12-18 h.

8. The advanced oxidation treatment device for dyeing and printing wastewater according to claim 7, characterized in that, The bottom of the inner cavity of the sealed reactor (1) is provided with a magnetic collection slope (9), which is equipped with a permanent magnet array with a magnetic field strength of 0.1~0.3T. This magnetic collection slope (9) is used to recover aged packing material. A water distribution plate (10) is provided at the bottom of the primary micro-electrolysis peroxide layer (6).

9. A method for advanced oxidation treatment of dyeing and printing wastewater, characterized in that, Includes the following steps: S1: Dyeing and printing wastewater with pH 5.5~6.5 is fed into the first-stage micro-electrolysis peroxide layer (6) through the feed inlet (2) and the water distribution plate (10); S2: The dyeing and printing wastewater is flowed into the secondary pH-responsive oxidation layer (7), and the pH rises to 7.5~8.0; S3: The dyeing and printing wastewater flows into the three-stage electron mediator buffer layer (8); S4: After running for 30-40 days, shut off the water inlet, recover the aged packing from the magnetic inclined plane, and regenerate it by soaking it in hydrochloric acid solution.

10. The method for advanced oxidation treatment of dyeing and printing wastewater according to claim 9, characterized in that, The hydraulic retention time in S1 is 1.5–2.5 h, dissolved oxygen is <0.3 mg / L, calcium peroxide slowly releases H2O2, and Fe... 0 Dissolved Fe 2+ Formation of Fenton-like reactions; The residence time in S2 is 2.0~3.0h, during which calcium persulfate releases S2O8. 2- , by Fe 2+ Activation produces SO4• - ; The residence time in S3 is 1.0~1.5h, Fe 3+ with Fe 2+ Cycle, SO4• - Continuous generation, SO4 2- Reducing bacteria compete with methanogens for substrates; The concentration of hydrochloric acid solution in S4 is 3~5wt%, and the soaking time is 1~2h.

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