Dyeing and finishing wastewater treatment system based on nylon fabric acid-controlled dyeing and finishing process

Abstract

The invention discloses a dyeing and finishing wastewater treatment system based on a nylon fabric acid-controlled dyeing and finishing process, and relates to the technical field of wastewater treatment, the dyeing and finishing wastewater treatment system comprises a wastewater collection pool, a pH regulation pool, a catalytic oxidation pool, a multi-stage adsorption filtration unit, a membrane separation device and a clear water reuse pool which are communicated in sequence; an inlet of the wastewater collecting tank is connected with a dyeing and finishing process drain pipe, an outlet of the wastewater collecting tank is communicated with a water inlet of the pH regulating tank through a lifting pump, a concentrated water outlet of the membrane separation device is connected to a water inlet end of the catalytic oxidation tank through a return pipe, and a clear water outlet of the membrane separation device is connected with the clear water recycling tank. According to the invention, through the multi-stage adsorption filtration unit, the gradient adsorption purification function on wastewater is realized, the problems of low adsorption capacity and poor selectivity of single zeolite are solved, and the material replacement frequency and the operation cost are remarkably reduced.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, in particular to a dyeing and finishing wastewater treatment system based on a nylon fabric acid-controlled dyeing and finishing process. Background Art

[0002] In the textile industry, nylon fabrics are widely used in high-end sportswear, outdoor gear, and other fields due to their excellent abrasion resistance, elasticity, and dyeing properties. Acid dyeing is a common dyeing method for nylon fabrics. The principle is to adjust the pH of the dye bath to acidic conditions (usually 4-6) so that the dye anions bind to the amino groups on the surface of the nylon fiber, achieving a bright color with high color fastness. However, the traditional nylon acid dyeing process has significant drawbacks. First, the dyeing process requires the use of large amounts of strong acids such as acetic acid and sulfuric acid to adjust the pH, resulting in highly acidic wastewater (pH ≤ 4), high chroma (up to 5,000 times), and COD concentrations as high as 15,000-20,000 mg / L. Second, dye utilization is low (usually only 70%-80%), and a large amount of unfixed dye is discharged with the wastewater, resulting in not only a waste of resources but also a serious threat to aquatic ecosystems.

[0003] Patent CN108529818B discloses a comprehensive dyeing and finishing waste treatment system. The above patent realizes the centralized treatment of large amounts of wastewater, solid waste and waste gas generated in the dyeing and finishing process, reducing the discharge of wastewater, solid waste and waste gas. At the same time, the three cooperate with each other to avoid secondary pollution to the environment caused by wastewater, solid waste and waste gas generated by the wastewater treatment system, sludge treatment system and waste gas treatment system.

[0004] The aforementioned patent effectively addresses waste gas pollution during the dyeing and finishing process by constructing a synergistic system encompassing waste gas and wastewater treatment. Its waste gas treatment system integrates multiple treatment units, including an SNCR denitrification reactor and a semi-dry quenching deacidification tower. The wastewater treatment system achieves wastewater purification and reuse through processes such as neutralization, filtration, and oxidation ditching. However, wastewater from the acid-controlled dyeing and finishing process for nylon fabrics not only contains conventional dyeing and finishing pollutants but also forms a specific acidic environment and a combination of refractory organic matter due to the acid-controlled process. This requires precise pH adjustment, deep organic matter removal, and efficient water reuse.

[0005] To this end, this application proposes a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, which can achieve synergistic oxidation through ultraviolet photocatalysis and ozone aeration, as well as directional treatment of acidic wastewater and reuse of clean water by composite adsorption. Summary of the Invention

[0006] The purpose of the present invention is to provide a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, so as to solve the technical problem proposed in the above-mentioned background technology that a large amount of strong acids such as acetic acid and sulfuric acid need to be used in the dyeing process to adjust the pH value, resulting in strong acidity of the wastewater, high COD concentration, low dye utilization rate, resulting in waste of resources, and also posing a serious threat to the aquatic ecosystem.

[0007] To achieve the above objectives, the present invention provides the following technical solutions: a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, comprising a wastewater collection tank, a pH adjustment tank, a catalytic oxidation tank, a multi-stage adsorption filtration unit, a membrane separation device, and a clean water reuse tank, which are connected in sequence; the inlet of the wastewater collection tank is connected to a dyeing and finishing process drain pipe, the outlet of the wastewater collection tank is connected to the water inlet of the pH adjustment tank via a lift pump, the concentrated water outlet of the membrane separation device is connected to the water inlet of the catalytic oxidation tank via a reflux pipe, and the clean water outlet of the membrane separation device is connected to the clean water reuse tank; The multi-stage adsorption filtration unit comprises an activated carbon adsorption layer and a composite zeolite layer, which are stacked up and down in series. The composite zeolite layer is formed by mixing and filling modified zeolite and nano-alumina particles.

[0008] Preferably, a pH sensor is provided at the middle of the inner wall of the pH regulating tank, and an automatic dosing device is provided at the top of the inner wall of the pH regulating tank; The automatic dosing device includes an alkali solution storage tank and an acid solution storage tank. The bottom of the alkali solution storage tank is connected to the dosing port of the pH adjustment tank through a first metering pump. A spiral nozzle is provided at the end of the alkali solution dosing pipe connected to the dosing port. The alkali solution dosing pipe extends to 20 cm above the bottom of the pH adjustment tank. The bottom of the acid solution storage tank is connected to the water inlet end of the catalytic oxidation tank through a second metering pump.

[0009] Preferably, the catalytic oxidation tank is provided with an ultraviolet catalytic component and an ozone aeration disk, the ultraviolet catalytic component is composed of an ultraviolet lamp group and a honeycomb ceramic plate, the ultraviolet lamp group is provided with a quartz sleeve, the ultraviolet lamp group includes a germicidal lamp with a main wavelength of 254nm and a catalytic lamp with a main wavelength of 365nm, the number ratio of the germicidal lamp to the catalytic lamp is 2:1, the outer wall of the honeycomb ceramic plate is loaded with titanium dioxide, and the honeycomb ceramic plate is arranged in a hexagonal channel structure, and the ozone aeration disk is connected to the external gas source through an ozone generator; The aeration holes of the ozone aeration plate have an aperture of 0.5-1 mm and are distributed in a circular array. The ozone aeration plate is fixedly installed at the bottom end of the inner wall of the catalytic oxidation tank. A baffle is provided 20 cm above the ozone aeration plate. The ultraviolet catalytic component is fixed to the inner wall of the catalytic oxidation tank through a bracket. The bracket suspends the ultraviolet catalytic component 10-20 cm above the liquid surface. The bottom of the bracket is detachably connected to the inner wall of the catalytic oxidation tank through a flange. The water inlet of the catalytic oxidation tank is arranged at the upper part of one side of the tank body, and the water outlet is arranged at the lower part of the other side of the tank body. The water inlet and the water outlet are arranged diagonally. A hydrogen peroxide doser is provided at the water inlet of the catalytic oxidation tank. The dosing pump of the hydrogen peroxide doser and the power control end of the ozone generator are respectively connected to the controller. The controller dynamically adjusts the addition ratio of hydrogen peroxide and ozone based on the COD value of the inlet water and the ORP value of the reaction system.

[0010] Preferably, the modified zeolite of the composite zeolite layer is clinoptilolite treated with a silane coupling agent, the particle size of the nano-alumina particles is 50-100 nm, and the mass ratio of the modified zeolite to the nano-alumina is 3:1; The activated carbon adsorption layer is filled in a stainless steel mesh frame. The activated carbon in the activated carbon adsorption layer is coconut shell activated carbon with a particle size of 2-4mm and a filling density of 400-600kg / m³. A backwash pipe is provided at the bottom of the activated carbon adsorption layer, and the backwash cycle is 24-48 hours. An exhaust port is provided at the top of the multi-stage adsorption filtration unit, and the exhaust port is connected to the activated carbon adsorber. The inside of the activated carbon adsorber is filled with granular activated carbon with an activated carbon particle size of 4-6mm and a filling height of 50-80cm.

[0011] Preferably, the membrane separation device includes a rolled nanofiltration membrane assembly and a porous central tube, the membrane of the rolled nanofiltration membrane assembly is spirally wound on the outer wall of the porous central tube, a flow control valve is fixedly installed at the concentrated water outlet of the rolled nanofiltration membrane assembly, a transparent detection pipe section is provided at the front end of the flow control valve, a conductivity detector is provided inside the transparent detection pipe section, and the clean water outlet is connected to a PE pipe; A safety filter is provided at the water inlet end of the membrane separation device. The filter element of the safety filter is a folded polypropylene filter element with a filtration accuracy of 5-10μm. A differential pressure sensor is provided on the outside of the filter element. The membrane pore size is 1-4nm and the operating pressure is 0.8-1.5Mpa. A protective shell is provided on the outside of the membrane separation device, and a shock-absorbing buffer layer is provided between the protective shell and the rolled nanofiltration membrane assembly.

[0012] Preferably, a sludge treatment unit is provided downstream of the catalytic oxidation tank sludge outlet; The sludge treatment unit includes a sedimentation tank, a sludge thickening tank and a plate and frame filter press. An ultrasonic oscillator is installed at the bottom of the sludge thickening tank, and the transducer of the ultrasonic oscillator is embedded in the inner wall of the sludge thickening tank. A stirring paddle is set on the top of the sludge thickening tank. The sludge thickening tank is connected to the sludge discharge port of the sedimentation tank through a screw pump, and the inlet of the sedimentation tank is connected to the sludge discharge port of the catalytic oxidation tank. The filtrate outlet of the plate and frame filter press is connected to the water inlet of the pH adjustment tank through a pipeline, and the feed port of the plate and frame filter press is connected to the bottom of the sludge thickening tank through a high-pressure hose.

[0013] Preferably, the sedimentation tank is provided with an inclined plate filler with an inclination angle of 60° and a plate spacing of 5-8 cm. The inclined plate filler is made of polypropylene with a thickness of 0.8-1.2 mm and a surface roughness Ra of 5-10 μm. The inclined plate filler is fixed to the inner wall of the sedimentation tank through a slot.

[0014] Preferably, the clean water reuse tank is connected to the rinsing water inlet of the dyeing and finishing process through a reuse water pump, and another part of the reuse water pump is connected to the backwash pipe. The outer wall of the backwash pipe is provided with a backwash water flow meter and a backwash water pressure gauge, and the backwash water flow meter and the backwash water pressure gauge are respectively connected to the controller through wireless communication technology; A residual chlorine detector and an activated carbon filter layer are installed inside the clean water reuse pool. The residual chlorine detector is fixedly installed at the outlet flange. The activated carbon filter layer is a columnar filling layer with a thickness of 50 cm. A stainless steel support net is set at the bottom of the activated carbon filter layer.

[0015] Preferably, the pH sensor is connected to the controller via a signal converter, the controller is connected to the signal converter via a data line, the signal converter is connected to the conductivity detector and the residual chlorine detector respectively, the controller is connected to the ozone generator, the first metering pump, the first metering pump and the flow control valve via a data bus, and the controller has a preset pH dynamic adjustment program; An intermediate water tank is set between the catalytic oxidation tank and the multi-stage adsorption filtration unit. The water inlet of the intermediate water tank is connected to the water outlet of the catalytic oxidation tank. The water outlet of the intermediate water tank is connected to the water inlet of the multi-stage adsorption filtration unit through a lifting pump. A liquid level sensor is set inside the intermediate water tank, and the liquid level sensor is connected to the controller signal.

[0016] Preferably, a grid and a pre-aeration device are provided inside the wastewater collection tank, the pre-aeration device is provided at the bottom of the wastewater collection tank, the grid is obliquely installed at the water inlet end of the wastewater collection tank, a vibration motor is provided under the grid, and the grid pitch of the grid is 2-4 mm; The pre-aeration device includes a microporous aeration head group and a Roots blower. The microporous aeration head group is distributed at the bottom of the wastewater collection tank. The spacing between the microporous aeration heads is 30 cm. The microporous aeration head group is connected to the Roots blower through a UPVC pipe to supply air. The air-water ratio is 3:1-5:1.

[0017] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention achieves gradient adsorption and purification of organic matter, heavy metal ions, and color in wastewater through a multi-stage adsorption and filtration unit, solving the problems of low adsorption capacity and poor selectivity of single zeolite, and significantly reducing the frequency of material replacement and operating costs; 2. This invention combines a UV-light catalytic component with an ozone aeration disk to achieve efficient catalytic oxidation degradation of refractory organic matter, solving the problems of high energy consumption and blind oxidant addition in traditional catalytic oxidation processes, and effectively improving the decomposition efficiency of azo dyes in nylon dyeing and finishing wastewater. 3. The present invention connects the membrane separation device to the catalytic oxidation tank to achieve water resource recycling, solve the problem of secondary pollution of concentrated water, and improve the solid-liquid separation efficiency; 4. The present invention realizes automatic measurement and control of the entire process from wastewater collection to clean water reuse through the automatic dosing device, solves the problems of traditional manual dosing lag and acid and alkali waste, and improves the system operation stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the overall process flow of the system of the present invention; Figure 2 It is a schematic structural diagram of the multi-stage adsorption filtration unit of the present invention; Figure 3 This is a schematic diagram of the process flow of the sludge treatment unit of the present invention; Figure 4 This is a topological diagram of the automatic control system of the present invention. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0020] See also Figure 1 、 Figure 2 、 Figure 3 and Figure 4 The present invention provides an embodiment: a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, comprising a wastewater collection tank, a pH adjustment tank, a catalytic oxidation tank, a multi-stage adsorption filtration unit, a membrane separation device and a clean water reuse tank connected in sequence; the inlet of the wastewater collection tank is connected to the dyeing and finishing process drain pipe, the outlet of the wastewater collection tank is connected to the water inlet of the pH adjustment tank through a lift pump, the concentrated water outlet of the membrane separation device is connected to the water inlet of the catalytic oxidation tank through a reflux pipe, and the clean water outlet of the membrane separation device is connected to the clean water reuse tank; The multi-stage adsorption filtration unit includes an activated carbon adsorption layer and a composite zeolite layer, which are stacked up and down in series, and the composite zeolite layer is filled with a mixture of modified zeolite and nano-alumina particles; The modified zeolite of the composite zeolite layer is clinoptilolite treated with a silane coupling agent, the particle size of the nano-alumina particles is 50-100 nm, and the mass ratio of the modified zeolite to the nano-alumina is 3:1; The activated carbon adsorption layer is filled in a stainless steel mesh frame. The activated carbon in the activated carbon adsorption layer is coconut shell activated carbon with a particle size of 2-4mm and a filling density of 400-600kg / m³. A backwash pipe is set at the bottom of the activated carbon adsorption layer, and the backwash cycle is 24-48 hours. An exhaust port is set at the top of the multi-stage adsorption filtration unit, and the exhaust port is connected to the activated carbon adsorber. The activated carbon adsorber is filled with granular activated carbon with a particle size of 4-6mm and a filling height of 50-80cm. Furthermore, first, the dyeing and finishing process drain pipe valve is opened to collect and pre-treat wastewater. The wastewater flows into the wastewater collection pool. The 3mm-pitch grid installed at a 30° angle in the pool intercepts large-particle impurities such as fibers and dye particles. The vibration motor below is started every 15 minutes with a vibration frequency of 50Hz. The eccentric wheel vibrates and shakes off the retained matter on the grid into the sewage collection hopper below. The Roots blower supplies air to the microporous aeration head group at an air-water ratio of 4:1. The micropores with a diameter of 2mm produce bubbles with a diameter of 1-3mm, which evenly stir the wastewater for 30 minutes to mix the water evenly and increase the dissolved oxygen to 3-4mg / L. Next, pH adjustment and catalytic oxidation are performed. A lift pump pumps wastewater into the pH adjustment tank at a flow rate of 5 m³ / h. A pH sensor in the center of the tank monitors water quality in real time. When the pH drops below 6.5, a controller receives a signal and triggers the first metering pump at the bottom of the alkali solution storage tank. The first metering pump sprays a 10% NaOH solution into the pH adjustment tank through a spiral nozzle, 20 cm from the tank bottom. The solution and wastewater are mixed by an internal agitator. Dosing stops when the pH reaches 7.5. The adjusted wastewater enters the catalytic oxidation tank from the upper side of the pH adjustment tank. The controller simultaneously activates the hydrogen peroxide doser and ozone generator. The germicidal lamp and the quartz sleeve outside the catalytic lamp of the UV photocatalytic assembly have a transmittance of ≥90%. The wastewater is irradiated 15 cm from the liquid surface. UV light excites the titanium dioxide loaded on the surface of the honeycomb ceramic plate with 5 mm hexagonal channels to generate hydroxyl radicals. The ozone released from the aeration holes of the ozone aeration plate forms an advanced oxidation system with hydrogen peroxide. The water inlet and outlet are set diagonally to form a plug flow reaction, and the reaction residence time is 60 minutes. Finally, after adsorption filtration, membrane separation, and water reuse, the catalytically oxidized wastewater flows by gravity into the intermediate tank. When the level sensor detects the water level reaches two-thirds of the tank, a lift pump pumps the wastewater at a flow rate of 8 m³ / h into the multi-stage adsorption filtration unit. First, it passes through the activated carbon adsorption layer composed of coconut shell activated carbon. The wastewater then flows from top to bottom through a stainless steel mesh frame for 30 minutes of adsorption. The bottom backwash pipe is activated every 24 hours, flushing the wastewater from bottom to top with clean water at 1.5 times the process flow rate for 10 minutes. It then enters the composite zeolite layer, a 3:1 mixture of modified clinoptilolite and 50nm nano-alumina particles. The zeolite is modified by soaking in a silane coupling agent for 24 hours, increasing its specific surface area to 300 m² / g. The nanoparticles fill the zeolite pores, enhancing the adsorption of heavy metal ions. After filtration, the wastewater enters the membrane separation unit. A safety filter with a pleated polypropylene element first removes particles ≥5μm. A differential pressure sensor monitors the filter element pressure differential. When the pressure differential exceeds 0.1MPa, it transmits an abnormality signal to the controller. The controller converts the digital signal to a graphic display on the front panel, prompting a replacement. A spiral nanofiltration membrane assembly separates the wastewater. Clean water flows through a PE pipe into the clean water reuse tank, while concentrated water returns to the inlet of the catalytic oxidation tank through a return pipe at a flow rate of 2m³ / h. The activated carbon filter layer in the clean water tank further absorbs trace organic matter. A residual chlorine detector monitors the water quality at the outlet in real time. Upon receiving the standard-reaching signal, the controller sends a signal to the reuse water pump to deliver the recycled water at a flow rate of 10m³ / h to the dyeing, finishing, and rinsing process.

[0021] See also Figure 1 、 Figure 2 and Figure 4 , an embodiment provided by the present invention: a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, wherein a pH sensor is provided in the middle of the side of the inner wall of the pH adjustment tank, and an automatic dosing device is provided at the top of the inner wall of the pH adjustment tank; The automatic dosing device includes an alkali solution storage tank and an acid solution storage tank. The bottom of the alkali solution storage tank is connected to the dosing port of the pH adjustment tank through a first metering pump. The end of the alkali solution dosing pipe connected to the dosing port is provided with a spiral nozzle. The alkali solution dosing pipe extends to 20 cm above the bottom of the pH adjustment tank. The bottom of the acid solution storage tank is connected to the water inlet of the catalytic oxidation tank through a second metering pump. A sludge treatment unit is provided downstream of the catalytic oxidation tank sludge outlet; The sludge treatment unit includes a sedimentation tank, a sludge thickening tank and a plate and frame filter press. An ultrasonic oscillator is installed at the bottom of the sludge thickening tank, and the transducer of the ultrasonic oscillator is embedded in the inner wall of the sludge thickening tank. A stirring paddle is set on the top of the sludge thickening tank. The sludge thickening tank is connected to the mud discharge port of the sedimentation tank through a screw pump. The inlet of the sedimentation tank is connected to the mud discharge port of the catalytic oxidation tank. The filtrate outlet of the plate and frame filter press is connected to the water inlet of the pH adjustment tank through a pipeline. The feed port of the plate and frame filter press is connected to the bottom of the sludge thickening tank through a high-pressure hose. Furthermore, when the ultrasonic level meter installed on the top of the wastewater collection tank detects that the liquid level has reached 80% of the total tank height, the meter's analog signal is transmitted via a shielded cable to the controller. The controller's built-in logic program immediately executes the following steps: 1. Signal Verification: This verifies the liquid level signal is stable within the 80% ± 2% range three times, with 10-second intervals between each step, to avoid false triggering. 2. Equipment Self-Test: This verifies the status of the lift pump via the MODBUS protocol. 3. Execution: The controller sends a start command to the VFD, which is directly connected to the lift pump. The VFD gradually increases its frequency from 5Hz to 50Hz to avoid starting current surges. Simultaneously, it outputs a switching signal to the indicator light on the lift pump control cabinet, opening the electric valve in the pipeline between the wastewater collection tank and the pH adjustment tank. The valve position feedback signal is then returned to the controller via a limit switch. This allows the controller to automatically control the lift pump to feed wastewater into the pH adjustment tank. A pH sensor located in the middle of the pH adjustment tank's inner wall collects data every 10 seconds, and the signal is transmitted to the controller via a signal converter. If the initial wastewater pH is 5.2 (typically acidic for nylon dyeing and finishing wastewater), the controller invokes a pre-set dynamic pH adjustment program to calculate the required amount of NaOH solution. The controller then activates the first metering pump, which delivers the alkali solution via a DN25 dosing pipe to a spiral nozzle 20 cm above the tank bottom, creating an atomized spray. Three sets of stirring paddles within the tank operate synchronously, with each set spaced 50 cm apart, ensuring thorough mixing of the solution and wastewater. When the pH sensor stabilizes at 7.8 (the optimal pH range for catalytic oxidation), the metering pump automatically stops. The adjustment process takes approximately 15 minutes. The conditioned wastewater then flows into the upper inlet of the catalytic oxidation tank. A controller uses a PID algorithm to calculate the hydrogen peroxide to ozone dosage ratio based on the inlet COD value and the reaction system's ORP value, as input by an online COD detector. When the ORP value rises to +600mV, the controller adjusts the hydrogen peroxide dosing pump frequency from 40Hz to 50Hz and simultaneously increases the ozone generator power from 80% to 100%. The UV lamp assembly of the UV photocatalytic assembly continuously illuminates the water, and the quartz sleeve is cleaned weekly with a soft brush to ensure light transmittance. The aeration holes of the ozone aeration plate, fixed to the tank bottom and 10cm from the tank wall, alternate at 0.5-second intervals, creating a pulsed ozone release. A baffle, half the diameter of the tank body and 20cm from the aeration plate, prevents water from directly impacting the tank wall, forcing the wastewater to circulate and extending the ozone contact time to 45 minutes. Finally, the wastewater after catalytic oxidation flows into the intermediate tank through a DN100 outlet pipe at the bottom of the tank. A level sensor within the wastewater tank monitors the water level in real time. When the water level falls below 20%, the lift pump automatically stops upon receiving a limit signal. When it rises above 80%, an alarm prompts the front-end processing equipment to slow down. The controller simultaneously collects data from the pH sensor, COD meter, and ORP meter to generate a real-time process curve. If the COD removal rate after catalytic oxidation is detected to be below 60% for three consecutive times, the UV lamp assembly and ozone aeration disk cleaning procedure is automatically triggered: the power is turned off, the UV assembly is removed through the bottom flange of the bracket, and the surface of the honeycomb ceramic plate is rinsed with deionized water to remove any deposits. The ozone aeration disk then purges the aeration holes with compressed air for 10 minutes through the backwash pipe.

[0022] See also Figure 1 、 Figure 2 and Figure 3 The present invention provides an embodiment of a dyeing and finishing wastewater treatment system based on a nylon fabric acid-controlled dyeing and finishing process, wherein the membrane separation device comprises a wound nanofiltration membrane assembly and a porous central tube, wherein the membrane of the wound nanofiltration membrane assembly is spirally wound around the outer wall of the porous central tube, a flow control valve is fixedly installed at the concentrated water outlet of the wound nanofiltration membrane assembly, a transparent detection pipe section is provided at the front end of the flow control valve, and a conductivity detector is provided inside the transparent detection pipe section, and the clean water outlet is connected to a PE pipe; A safety filter is provided at the water inlet end of the membrane separation device. The filter element of the safety filter is a folded polypropylene filter element with a filtration accuracy of 5-10μm. A differential pressure sensor is provided on the outside of the filter element. The membrane pore size is 1-4nm and the operating pressure is 0.8-1.5Mpa. A protective shell is provided on the outside of the membrane separation device, and a shock-absorbing buffer layer is provided between the protective shell and the rolled nanofiltration membrane assembly. The catalytic oxidation tank is provided with an ultraviolet catalytic component and an ozone aeration disk. The ultraviolet catalytic component is composed of an ultraviolet lamp group and a honeycomb ceramic plate. The ultraviolet lamp group is provided with a quartz sleeve. The ultraviolet lamp group includes a germicidal lamp with a main wavelength of 254nm and a catalytic lamp with a main wavelength of 365nm. The number ratio of the germicidal lamp to the catalytic lamp is 2:1. The outer wall of the honeycomb ceramic plate is loaded with titanium dioxide. The honeycomb ceramic plate is arranged in a hexagonal channel structure. The ozone aeration disk is connected to an external gas source through an ozone generator. The aeration holes of the ozone aeration plate have an aperture of 0.5-1 mm and are distributed in a circular array. The ozone aeration plate is fixedly installed at the bottom end of the inner wall of the catalytic oxidation tank. A baffle is provided 20 cm above the ozone aeration plate. The ultraviolet catalytic component is fixed to the inner wall of the catalytic oxidation tank through a bracket. The bracket suspends the ultraviolet catalytic component 10-20 cm above the liquid surface. The bottom of the bracket is detachably connected to the inner wall of the catalytic oxidation tank through a flange. The water inlet of the catalytic oxidation tank is provided at the upper part of one side of the tank body, and the water outlet is provided at the lower part of the other side of the tank body. The water inlet and the water outlet are provided diagonally. A hydrogen peroxide doser is provided at the water inlet of the catalytic oxidation tank. The dosing pump of the hydrogen peroxide doser and the power control end of the ozone generator are respectively connected to a controller. The controller dynamically adjusts the addition ratio of hydrogen peroxide and ozone based on the COD value of the inlet water and the ORP value of the reaction system. Furthermore, a pneumatic butterfly valve is installed at the front end of the exhaust port, located vertically in the center of the top of the multi-stage adsorption filtration unit, and a rain cap is installed at the outlet end. As wastewater is lifted from the intermediate pool and enters the multi-stage adsorption filtration unit, the top exhaust port is initially opened for 30 seconds. Air within the multi-stage adsorption filtration unit is naturally expelled by gravity and water pre-pressure, preventing air blockage in the pores between the activated carbon adsorption layer and the composite zeolite layer, which can lead to uneven water flow distribution. The wastewater first encounters the activated carbon adsorption layer: a stainless steel mesh frame filled with coconut shell activated carbon at a density of 600 kg / m³, forming a filtration layer with a porosity of 45%. Wastewater passes from top to bottom at a filtration rate of 0.5m / h. The micropores on the surface of the activated carbon adsorb dye molecules and organic matter. After running for 24 hours, backwashing is started: the water inlet valve is closed, the backwash pipe valve is opened, and the recycled water from the clean water reuse pool is reversely flushed from the bottom backwash pipe at a flow rate of 15m³ / h and a water flow rate of 2m / s for 15 minutes. The retained impurities are flushed to the drainage ditch. After the backwash is completed, the exhaust port is opened again for 5 seconds to balance the pressure. The wastewater, having undergone activated carbon adsorption, then enters the upper composite zeolite layer. The modified clinoptilolite is treated with the silane coupling agent KH-550. The zeolite is immersed in a 5% ethanol solution of the coupling agent, stirred in a 60°C water bath for two hours, filtered, and then dried at 100°C for four hours. This grafts amino groups onto the surface, increasing its adsorption capacity for heavy metal ions such as Cu²+ and Zn²+ by 40%. Nanoalumina particles and modified zeolite are mixed in a mixer at a mass ratio of 3:1 for 30 minutes and evenly distributed throughout the filter layer. Wastewater flows upward, where the ion exchange activity of the zeolite and the surface adsorption of the nanoparticles synergistically remove residual pollutants for a residence time of 20 minutes. An activated carbon adsorber connected to the top exhaust port operates simultaneously to absorb small amounts of organic waste gases emitted during the filtration process. The activated carbon is replaced quarterly. Finally, the filtered wastewater enters the membrane separation unit through a pipeline. It first passes through a safety filter, where a differential pressure sensor on the outside of the filter element monitors the filter element in real time. When the differential pressure reaches 0.2 MPa, a signal is issued for replacement. The wastewater enters the spiral nanofiltration membrane assembly at a pressure of 1.0 MPa. The membrane is spirally wound around a porous central tube, forming a filtration unit with a flow channel width of 0.8 mm. The flow control valve at the reject water outlet adjusts its opening based on the conductivity meter's readings. When the reject water conductivity is ≥1500 μS / cm, the valve remains at 80% opening, allowing the reject water to flow back to the catalytic oxidation tank at a rate of 3 m³ / h. When the reject water conductivity is below 1000 μS / cm, the valve opening is adjusted to 60% to minimize backflow. The PE pipe at the clean water outlet is equipped with an online turbidity meter. When the test value is <0.5 NTU, the reject water enters the clean water reuse tank. Otherwise, the system automatically switches to a backwash process, flushing the membrane surface with clean water at 1.5 times the operating flow rate for 10 minutes to restore membrane flux.

[0023] See also Figure 1 、 Figure 3 and Figure 4 The present invention provides an embodiment of a dyeing and finishing wastewater treatment system based on a nylon fabric acid-controlled dyeing and finishing process, wherein an inclined plate filler is provided in the sedimentation tank, the inclined plate has an inclination angle of 60°, the plate spacing is 5-8 cm, the inclined plate filler is made of polypropylene, has a thickness of 0.8-1.2 mm, and a surface roughness Ra of 5-10 μm, and the inclined plate filler is fixedly mounted on the inner wall of the sedimentation tank through a slot; The clean water reuse tank is connected to the rinsing water inlet of the dyeing and finishing process through a reuse water pump, and the other end of the reuse water pump is connected to the backwash pipe. The outer wall of the backwash pipe is provided with a backwash water flow meter and a backwash water pressure gauge. The backwash water flow meter and the backwash water pressure gauge are respectively connected to the controller through wireless communication technology; A residual chlorine detector and activated carbon filter layer are installed inside the clean water reuse pool. The residual chlorine detector is fixedly installed at the outlet flange. The activated carbon filter layer is a columnar filling layer with a thickness of 50 cm. A stainless steel support mesh is installed at the bottom of the activated carbon filter layer. Furthermore, first, the solid-liquid separation is carried out in the sedimentation tank, and the sludge outlet of the catalytic oxidation tank located at the center of the bottom of the tank is opened regularly, once a day for 10 minutes each time, to discharge the sludge-containing wastewater into the sedimentation tank. The inclined plate filler in the tank is installed at a 60° angle, with a plate spacing of 6cm, and is fixed to the tank wall through a slot. Wastewater flows into the sedimentation tank from the lower water inlet, rises along the channel between the inclined plates, and the flow rate is controlled at 0.3mm / s. The sludge particles are mainly titanium dioxide catalytic slag and organic flocculants. Under the action of gravity, they slide along the surface of the inclined plate to the bottom of the tank, and the separation efficiency is increased by 30% compared with the traditional horizontal flow sedimentation tank. The inclined plate is manually cleaned once a month, and the sediment on the plate surface is flushed with a high-pressure water gun to prevent clogging. Next, the sludge discharge pipe at the bottom of the sedimentation tank, equipped with a pneumatic diaphragm valve, is opened every two hours to pump the sludge into the sludge thickening tank. An ultrasonic oscillator embedded in the tank bottom operates for 30 minutes, followed by a 10-minute pause. This cavitation effect breaks up sludge flocs and promotes water release. A stirring paddle at the top continuously agitates the sludge to prevent sedimentation. During the thickening process, the sludge moisture content decreases from 98% to 95%. When the liquid level in the tank reaches 80%, the screw pump is activated to transfer the sludge to the plate and frame filter press. Before feeding the filter press, a 0.1% polyacrylamide solution is added to the thickening tank at a dosage of 5 kg / m³ of sludge and mixed for 15 minutes to improve sludge dewatering performance. Finally, after the plate and frame filter press is turned on, a high-pressure hose pumps the conditioned sludge into the filter chamber. When the feed pressure reaches 0.8 MPa, the feed is stopped and the pressure is maintained for 30 minutes. A monofilament polyester filter cloth intercepts the sludge particles, allowing the filtrate to pass through the cloth and flow through the filtrate outlet into a pipeline. A solenoid valve switches the filter directly back to the pH adjustment tank inlet. If the filtrate exceeds the pH standard, a controller receives a signal to switch the solenoid valve, discharging the excess filtrate into a wastewater collection tank. After filtration is complete, the filter plates are released, and a mechanical scraper automatically removes the sludge cake, which is collected and transported for disposal. Each batch of filtration takes two hours, and the filter cloth is rinsed with a neutral detergent once a week to prevent clogging.

[0024] See also Figure 1 、 Figure 3 and Figure 4 The present invention provides an embodiment: a dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, wherein a grid and a pre-aeration device are arranged inside the wastewater collection tank, the pre-aeration device is arranged at the bottom of the wastewater collection tank, the grid is installed obliquely at the water inlet end of the wastewater collection tank, a vibration motor is arranged under the grid, and the grid pitch of the grid is 2-4 mm; The pre-aeration device includes a microporous aeration head group and a Roots blower. The microporous aeration head group is distributed at the bottom of the wastewater collection tank. The microporous aeration head spacing is 30cm. The microporous aeration head group is connected to the Roots blower through a UPVC pipe to supply air. The air-water ratio is 3:1-5:1. The pH sensor is connected to the controller via a signal converter, the controller is connected to the signal converter via a data line, the signal converter is connected to the conductivity detector and the residual chlorine detector respectively, the controller is connected to the ozone generator, the first metering pump, the first metering pump and the flow control valve via a data bus, and a pH dynamic adjustment program is preset in the controller; An intermediate water tank is set between the catalytic oxidation tank and the multi-stage adsorption filtration unit, the water inlet of the intermediate water tank is connected to the water outlet of the catalytic oxidation tank, the water outlet of the intermediate water tank is connected to the water inlet of the multi-stage adsorption filtration unit through a lifting pump, and a liquid level sensor is set inside the intermediate water tank, and the liquid level sensor is connected to the controller signal; First, the clean water from the membrane separation unit enters the clean water reuse tank. A stainless steel support mesh at the bottom of the tank supports a 50cm-thick columnar activated carbon filter layer, through which the wastewater passes upward for 15 minutes, further absorbing residual trace dyes and disinfection byproducts. A residual chlorine detector at the outlet flange provides real-time monitoring. When the measured value exceeds 0.5mg / L, the controller initiates a backwash procedure for the activated carbon filter layer: the valve at the bottom of the tank is opened, and recycled water is flushed at 1.2 times the process flow rate for 20 minutes to remove excess residual chlorine and adsorbed materials on the activated carbon surface. Two reuse water pumps are then installed in the clean water reuse tank. The main pump is connected to the rinse water inlet of the dyeing and finishing process via a DN100 pipe. An electromagnetic flowmeter and pressure sensor are installed on the pipe to monitor the reuse water volume and pressure in real time. Another backwash pipe is connected to the backwash port of the activated carbon adsorption layer of the multi-stage adsorption filtration unit. The backwash water flowmeter and pressure gauge in the pipe transmit data to the controller via a wireless communication module. When the activated carbon adsorption layer requires backwashing, the controller switches the pump valve. The differential pressure sensor triggers the controller to prioritize the backwash request. After the backwash is completed, the controller closes the backwash butterfly valve and keeps the pump running for 30 seconds to drain any remaining rinse water in the channel. The valve is then switched back to its original position to resume reuse mode. Finally, the controller integrates all sensor signals: the vibrating screen motor and pre-aeration fan in the wastewater collection tank; the dosing pump and agitator in the pH adjustment tank; the UV lamp and ozone generator in the catalytic oxidation tank; the level sensor in the intermediate tank; the backwash valve in the multi-stage adsorption filtration unit; the flow control valve and conductivity meter in the membrane separation unit; and the residual chlorine detector in the fresh water reuse tank. All are connected via an RS485 bus. The user interface displays the operating parameters of each unit in real time, with preset alarm thresholds. If the ORP value in the catalytic oxidation tank is less than +400mV for more than 10 minutes, or the pressure differential in the membrane separation unit exceeds 0.3MPa, the system automatically generates an audible and visual alarm, suspends water intake, and sends a text message to the administrator's mobile phone. Daily operation reports are automatically generated, recording data such as treated water volume, chemical consumption, and equipment operating time, with storage for one year. The system automatically calibrates the pH sensor weekly using standard buffer.

[0025] Working Principle: Dyeing and finishing wastewater enters the wastewater collection tank through a drainage pipe. A grid within the tank removes larger solid impurities. A pre-aeration device aerates the wastewater through microporous aeration heads, providing initial mixing and pretreatment. The wastewater is then pumped to the pH adjustment tank via a lift pump. In the pH adjustment tank, a pH sensor monitors the wastewater's pH in real time. A controller, based on the monitoring data, controls the automatic dosing device, adding chemicals from either the alkali or acid storage tanks to the tank, adjusting the wastewater's pH to a range suitable for catalytic oxidation. The pH-adjusted wastewater then enters the catalytic oxidation tank. The ozone aeration disk within the tank releases ozone, while the UV lamps in the UV photocatalytic assembly work synergistically with the titanium dioxide-loaded honeycomb ceramic plates. Through the combined catalytic oxidation of UV light and ozone, organic pollutants in the wastewater are broken down and degraded. The treated wastewater then enters a multi-stage adsorption filtration unit, where it first passes through an activated carbon adsorption layer to absorb organic impurities and odors, and then passes through a composite zeolite layer to further absorb pollutants such as heavy metal ions. Finally, the wastewater that has undergone adsorption filtration enters the membrane separation unit, where it is separated by spiral nanofiltration membrane modules. The clean water flows through the clean water outlet into the clean water reuse tank, while the concentrated water returns to the catalytic oxidation tank through the return pipe for further treatment. The sludge produced in the catalytic oxidation tank enters the sludge treatment unit through the sludge outlet, where it is treated in a sedimentation tank, sludge thickening tank, and plate and frame filter press. The filtrate returns to the pH adjustment tank for further recycling.

[0026] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process of nylon fabrics, characterized by: It includes a wastewater collection tank, a pH adjustment tank, a catalytic oxidation tank, a multi-stage adsorption filtration unit, a membrane separation device and a clean water reuse tank which are connected in sequence; The inlet of the wastewater collection tank is connected to the dyeing and finishing process drain pipe, the outlet of the wastewater collection tank is connected to the water inlet of the pH adjustment tank through a lifting pump, the concentrated water outlet of the membrane separation device is connected to the water inlet of the catalytic oxidation tank through a reflux pipe, and the clean water outlet of the membrane separation device is connected to the clean water reuse tank; The multi-stage adsorption filtration unit comprises an activated carbon adsorption layer and a composite zeolite layer, which are stacked up and down in series. The composite zeolite layer is formed by mixing and filling modified zeolite and nano-alumina particles.

2. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: A pH sensor is provided in the middle of the inner wall of the pH regulating tank, and an automatic dosing device is provided at the top of the inner wall of the pH regulating tank; The automatic dosing device includes an alkali solution storage tank and an acid solution storage tank. The bottom of the alkali solution storage tank is connected to the dosing port of the pH adjustment tank through a first metering pump. A spiral nozzle is provided at the end of the alkali solution dosing pipe connected to the dosing port. The alkali solution dosing pipe extends to 20 cm above the bottom of the pH adjustment tank. The bottom of the acid solution storage tank is connected to the water inlet end of the catalytic oxidation tank through a second metering pump.

3. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: The catalytic oxidation tank is provided with an ultraviolet catalytic component and an ozone aeration disk. The ultraviolet catalytic component is composed of an ultraviolet lamp group and a honeycomb ceramic plate. The ultraviolet lamp group is provided with a quartz sleeve. The ultraviolet lamp group includes a germicidal lamp with a main wavelength of 254nm and a catalytic lamp with a main wavelength of 365nm. The number ratio of the germicidal lamp to the catalytic lamp is 2:

1. The outer wall of the honeycomb ceramic plate is loaded with titanium dioxide. The honeycomb ceramic plate is arranged in a hexagonal channel structure. The ozone aeration disk is connected to an external gas source through an ozone generator. The aeration holes of the ozone aeration plate have an aperture of 0.5-1 mm and are distributed in a circular array. The ozone aeration plate is fixedly installed at the bottom end of the inner wall of the catalytic oxidation tank. A baffle is provided 20 cm above the ozone aeration plate. The ultraviolet catalytic component is fixed to the inner wall of the catalytic oxidation tank through a bracket. The bracket suspends the ultraviolet catalytic component 10-20 cm above the liquid surface. The bottom of the bracket is detachably connected to the inner wall of the catalytic oxidation tank through a flange. The water inlet of the catalytic oxidation tank is arranged at the upper part of one side of the tank body, and the water outlet is arranged at the lower part of the other side of the tank body. The water inlet and the water outlet are arranged diagonally. A hydrogen peroxide doser is provided at the water inlet of the catalytic oxidation tank. The dosing pump of the hydrogen peroxide doser and the power control end of the ozone generator are respectively connected to the controller. The controller dynamically adjusts the addition ratio of hydrogen peroxide and ozone based on the COD value of the inlet water and the ORP value of the reaction system.

4. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: The modified zeolite of the composite zeolite layer is clinoptilolite treated with a silane coupling agent, the particle size of the nano-alumina particles is 50-100 nm, and the mass ratio of the modified zeolite to the nano-alumina is 3:1; The activated carbon adsorption layer is filled in a stainless steel mesh frame. The activated carbon in the activated carbon adsorption layer is coconut shell activated carbon with a particle size of 2-4mm and a filling density of 400-600kg / m³. A backwash pipe is provided at the bottom of the activated carbon adsorption layer, and the backwash cycle is 24-48 hours. An exhaust port is provided at the top of the multi-stage adsorption filtration unit, and the exhaust port is connected to the activated carbon adsorber. The inside of the activated carbon adsorber is filled with granular activated carbon with an activated carbon particle size of 4-6mm and a filling height of 50-80cm.

5. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: The membrane separation device includes a rolled nanofiltration membrane assembly and a porous central tube. The membrane of the rolled nanofiltration membrane assembly is spirally wound on the outer wall of the porous central tube. A flow control valve is fixedly installed at the concentrated water outlet of the rolled nanofiltration membrane assembly. A transparent detection pipe section is provided at the front end of the flow control valve. A conductivity detector is provided inside the transparent detection pipe section. The clean water outlet is connected to a PE pipe. A safety filter is provided at the water inlet end of the membrane separation device. The filter element of the safety filter is a folded polypropylene filter element with a filtration accuracy of 5-10μm. A differential pressure sensor is provided on the outside of the filter element. The membrane pore size is 1-4nm and the operating pressure is 0.8-1.5Mpa. A protective shell is provided on the outside of the membrane separation device, and a shock-absorbing buffer layer is provided between the protective shell and the rolled nanofiltration membrane assembly.

6. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: A sludge treatment unit is provided downstream of the catalytic oxidation tank sludge outlet; The sludge treatment unit includes a sedimentation tank, a sludge thickening tank and a plate and frame filter press. An ultrasonic oscillator is installed at the bottom of the sludge thickening tank, and the transducer of the ultrasonic oscillator is embedded in the inner wall of the sludge thickening tank. A stirring paddle is set on the top of the sludge thickening tank. The sludge thickening tank is connected to the sludge discharge port of the sedimentation tank through a screw pump, and the inlet of the sedimentation tank is connected to the sludge discharge port of the catalytic oxidation tank. The filtrate outlet of the plate and frame filter press is connected to the water inlet of the pH adjustment tank through a pipeline, and the feed port of the plate and frame filter press is connected to the bottom of the sludge thickening tank through a high-pressure hose.

7. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 6, characterized in that: The sedimentation tank is provided with an inclined plate filler with an inclination angle of 60° and a plate spacing of 5-8 cm. The inclined plate filler is made of polypropylene with a thickness of 0.8-1.2 mm and a surface roughness Ra of 5-10 μm. The inclined plate filler is fixedly installed on the inner wall of the sedimentation tank through a slot.

8. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: The clean water reuse tank is connected to the rinsing water inlet of the dyeing and finishing process through a reuse water pump, and the other end of the reuse water pump is connected to the backwash pipe. The outer wall of the backwash pipe is provided with a backwash water flow meter and a backwash water pressure gauge. The backwash water flow meter and the backwash water pressure gauge are respectively connected to the controller through wireless communication technology; A residual chlorine detector and an activated carbon filter layer are installed inside the clean water reuse pool. The residual chlorine detector is fixedly installed at the outlet flange. The activated carbon filter layer is a columnar filling layer with a thickness of 50 cm. A stainless steel support net is set at the bottom of the activated carbon filter layer.

9. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 2, characterized in that: The pH sensor is connected to the controller via a signal converter, the controller is connected to the signal converter via a data line, the signal converter is connected to the conductivity detector and the residual chlorine detector respectively, the controller is connected to the ozone generator, the first metering pump, the first metering pump and the flow control valve via a data bus, and a pH dynamic adjustment program is preset in the controller; An intermediate water tank is set between the catalytic oxidation tank and the multi-stage adsorption filtration unit. The water inlet of the intermediate water tank is connected to the water outlet of the catalytic oxidation tank. The water outlet of the intermediate water tank is connected to the water inlet of the multi-stage adsorption filtration unit through a lifting pump. A liquid level sensor is set inside the intermediate water tank, and the liquid level sensor is connected to the controller signal.

10. The dyeing and finishing wastewater treatment system based on the acid-controlled dyeing and finishing process for nylon fabrics according to claim 1, characterized in that: A grid and a pre-aeration device are provided inside the wastewater collection tank. The pre-aeration device is provided at the bottom of the wastewater collection tank. The grid is tilted and installed at the water inlet end of the wastewater collection tank. A vibration motor is provided under the grid. The grid pitch is 2-4 mm. The pre-aeration device includes a microporous aeration head group and a Roots blower. The microporous aeration head group is distributed at the bottom of the wastewater collection tank. The spacing between the microporous aeration heads is 30 cm. The microporous aeration head group is connected to the Roots blower through a UPVC pipe to supply air. The air-water ratio is 3:1-5:1.

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