Short-process efficient printing and dyeing wastewater RO concentrated water treatment system

Abstract

The utility model relates to the field of printing and dyeing wastewater treatment, in particular to a short-process efficient printing and dyeing wastewater RO concentrated water treatment system. The short-process and high-efficiency RO concentrated water treatment system for the printing and dyeing wastewater comprises an electric flocculation tank, an inclined tube sedimentation tank, an HMF tank and an electrodialysis device which are arranged in sequence. In order to overcome the defects of multiple processes, complex route and the like of the existing printing and dyeing wastewater RO concentrated water treatment process, the electric flocculation, sedimentation tank, HMF and electrodialysis combined equipment with short processes is designed, so that RO concentrated water pollutants can be effectively removed, the process flow is short, and the operation is simple.

Description

Technical Field

[0001] The utility model relates to the field of printing and dyeing wastewater treatment, in particular to a short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater. Background Art

[0002] In recent years, the printing and dyeing industry has rapidly developed and has become one of the nation's pillar industries. While generating economic benefits, it also generates a massive amount of printing and dyeing wastewater. Printing and dyeing wastewater is discharged from printing and dyeing mills, wool dyeing and finishing, and silk mills, primarily processing cotton, linen, chemical fibers and their blends, and silk. Characterized by large volumes of water, high levels of organic pollutants, high alkalinity, and significant variability in water quality, it is a difficult-to-treat industrial wastewater, containing dyes, slurries, additives, oils, acids and alkalis, fiber impurities, sand, and inorganic salts. Currently, secondary treatment processes for printing and dyeing wastewater primarily rely on physical and chemical methods and biological treatment. While biological treatment offers good organic matter removal rates, the BOD / COD ratio decreases after biological treatment, resulting in poor biodegradability. At the same time, a growing number of printing and dyeing plants are experiencing a growing demand for recycled water. Most companies are using a dual-membrane process for reclaimed water reuse, employing either an MBR or UF process combined with a NF or RO process to intercept and filter biochemical wastewater. The produced water can be directly reused, while the concentrate is discharged to other sewage treatment plants for further treatment. However, due to its high concentration ratio, high salt content, high concentration of recalcitrant organic matter, high color, and low BOD / COD ratio, conventional biochemical and physicochemical methods are unable to effectively treat RO concentrate. Furthermore, due to the large amount of inorganic salt additives added during the printing and dyeing process, the concentrate contains a large amount of inorganic salts after concentration. Direct discharge not only reduces the biodegradability of the industrial park's sewage treatment plant, but also increases the difficulty of subsequent treatment and results in a significant waste of inorganic salts and water resources.

[0003] Currently, there are four general treatment methods for RO concentrate from printing and dyeing wastewater in the industry. The first is to treat the RO concentrate by directly discharging it to the next-level sewage treatment plant if it meets the water quality standards. The second is to treat the RO concentrate by using a simple physicochemical method to bring it up to the corresponding standards before discharge. The third is to directly treat the RO concentrate using an evaporation system. This method can achieve zero-discharge treatment of printing and dyeing wastewater, but it consumes a lot of energy. The fourth is to design an additional process to recycle the water and inorganic salts contained in the RO concentrate based on the water quality characteristics of the RO concentrate. However, the existing process is not mature enough and has disadvantages such as multiple process flows, complex operation, and high energy consumption. Therefore, designing a convenient, short-cycle wastewater treatment system for RO concentrate from printing and dyeing wastewater can improve resource reuse while treating the wastewater, bringing many benefits.

[0004] The existing technology has the following problems: 1. Directly discharging the RO concentrate from printing and dyeing wastewater will lead to a large amount of water resources and inorganic salt resources in the concentrate being wasted, and will also increase the biochemical burden of the next-level sewage treatment plant; 2. Directly using the evaporation process to treat the RO concentrate from printing and dyeing wastewater consumes huge operating energy and causes excessive evaporation and crystallization of inorganic salt impurities, making it unusable; 3. The conventional RO concentrate resource reuse process for printing and dyeing wastewater has a long process and a complex process route. When combined with MVR evaporation technology, the process consumes high energy and is costly.

[0005] Prior art CN115448477A proposes a method for advanced treatment of printing and dyeing wastewater and reuse of recycled water. The wastewater undergoes sand filtration and fine filtration pretreatment, followed by ultrafiltration, adsorption, and primary reverse osmosis treatment. The primary reverse osmosis concentrate undergoes secondary reverse osmosis treatment, with the produced water collected for reuse as recycled water. The RO concentrate undergoes further advanced treatment to remove organic impurities before evaporation. While this method utilizes the RO process to significantly increase water reuse, the treatment of the RO concentrate is unclear. Ultimately, evaporation is used for salt reuse, requiring appropriate disposal of the RO concentrate. Summary of the Invention

[0006] This utility model hopes to provide a short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater. The specific scheme is as follows:

[0007] A short-process and efficient RO concentrate treatment system for printing and dyeing wastewater includes an electric flocculation tank, an inclined tube sedimentation tank, a high-intensity submerged membrane filtration (HMF) tank and an electrodialysis device which are arranged in sequence.

[0008] The electric flocculation tank includes an electric flocculation tank water inlet pipe, an electric flocculation cathode plate, an electric flocculation anode plate, an electric flocculation mud collecting hopper, an electric flocculation water outlet and an electric flocculation water outlet channel. The electric flocculation tank water inlet pipe is located at the lower left of the electric flocculation tank, the electric flocculation water outlet is located at the upper right of the electric flocculation tank, and the electric flocculation cathode plate and the electric flocculation anode plate are arranged in an alternating manner.

[0009] The inclined tube sedimentation tank includes an inclined tube sedimentation tank water inlet, an inclined tube, an inclined tube sedimentation tank mud collecting hopper, an inclined tube sedimentation tank water collecting trough and an inclined tube sedimentation tank water outlet. Water collecting trough water inlet holes are distributed on both sides of the inclined tube sedimentation tank water collecting trough. The water inlet of the inclined tube sedimentation tank is located at the lower left side of the inclined tube sedimentation tank, and the water outlet of the inclined tube sedimentation tank is located at the upper right side of the inclined tube sedimentation tank.

[0010] The HMF pool includes a hollow fiber ultrafiltration membrane component, an aeration system, an HMF pool sludge collecting hopper and an HMF pool water production pipeline.

[0011] The electrodialysis device includes an electrodialysis anion exchange membrane, an electrodialysis cation exchange membrane, an electrodialysis dilute chamber, an electrodialysis concentrate chamber, an electrodialysis concentrate chamber outlet pipe, an electrodialysis dilute chamber outlet pipe, an electrodialysis fresh water tank, an electrodialysis concentrate water tank, an electrodialysis anode chamber, an electrodialysis cathode chamber and a mud conveying pipeline. The electrodialysis concentrate chamber is connected to the electrodialysis concentrate water tank via the electrodialysis concentrate chamber outlet pipe, and the electrodialysis dilute chamber is connected to the electrodialysis dilute chamber water tank via the electrodialysis dilute chamber outlet pipe.

[0012] The utility model has the following advantages:

[0013] 1. To address the resource waste and environmental pollution caused by the discharge of RO concentrate from printing and dyeing wastewater, a short-process "electrocoagulation + sedimentation tank + HMF + electrodialysis" wastewater treatment system was designed to recycle a large amount of inorganic salt resources and water resources, achieving efficient treatment of RO concentrate from printing and dyeing wastewater;

[0014] 2. To address the high energy consumption and high concentration of crystallized salt contaminants in existing RO brine treatment technologies, the combined use of "electrocoagulation + HMF" equipment effectively removes most organic contaminants and inorganic substances, such as calcium and magnesium ions, from RO brine, significantly improving water quality. Finally, electrodialysis can replace the MVR evaporation system to achieve inorganic salt reuse.

[0015] 3. In view of the shortcomings of the existing RO concentrated water treatment process for printing and dyeing wastewater, such as multiple processes and complex routes, a short-process "electrocoagulation + sedimentation tank + HMF + electrodialysis" combined system is designed to effectively remove RO concentrated water pollutants with a short process flow and simple operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a structural diagram of a short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater in the utility model;

[0017] The numbers are: 1-water inlet of electro-flocculation tank; 2-cathode plate of electro-flocculation; 3-anode plate of electro-flocculation; 4-mud collecting hopper of electro-flocculation; 5-water outlet of electro-flocculation; 6-water outlet channel of electro-flocculation; 7-water inlet of inclined tube sedimentation tank; 8-inclined tube; 9-mud collecting hopper of inclined tube sedimentation tank; 10-water collecting tank of inclined tube sedimentation tank; 11-water inlet hole of water collecting tank; 12-water outlet of inclined tube sedimentation tank; 13-hollow fiber ultrafiltration membrane module; 14-HMF exposure Gas system; 15-HMF pool mud collecting hopper; 16-HMF pool water production pipeline; 17-electrodialysis anion exchange membrane; 18-electrodialysis cation exchange membrane; 19-electrodialysis dilute chamber; 20-electrodialysis concentrate chamber; 21-electrodialysis concentrate chamber outlet pipe; 22-electrodialysis dilute chamber outlet pipe; 23-electrodialysis fresh water tank; 24-electrodialysis concentrate tank; 25-electrodialysis anode chamber; 26-electrodialysis cathode chamber; 27-sludge transport pipeline. DETAILED DESCRIPTION

[0018] The following combination Figure 1 For further explanation:

[0019] A short-process and efficient RO concentrate treatment system for printing and dyeing wastewater includes an electric flocculation tank, an inclined tube sedimentation tank, a high-intensity submerged membrane filtration (HMF) tank and an electrodialysis device which are arranged in sequence.

[0020] The electrocoagulation tank includes an electrocoagulation tank water inlet pipe 1, an electrocoagulation cathode plate 2, an electrocoagulation anode plate 3, an electrocoagulation sludge collecting hopper 4, an electrocoagulation water outlet 5 and an electrocoagulation water outlet channel 6. The electrocoagulation tank water inlet pipe 1 is located at the lower left of the electrocoagulation tank, the electrocoagulation water outlet 5 is located at the upper right of the electrocoagulation tank, and the electrocoagulation cathode plate 2 and the electrocoagulation anode plate 3 are arranged alternately.

[0021] The inclined tube sedimentation tank includes an inclined tube sedimentation tank water inlet 7, an inclined tube 8, an inclined tube sedimentation tank mud collecting hopper 9, an inclined tube sedimentation tank water collecting trough 10 and an inclined tube sedimentation tank water outlet 12. Water collecting trough water inlet holes 11 are distributed on both sides of the inclined tube sedimentation tank water collecting trough 10. The inclined tube sedimentation tank water inlet 7 is located at the lower left side of the inclined tube sedimentation tank, and the inclined tube sedimentation tank water outlet 12 is located at the upper right side of the inclined tube sedimentation tank.

[0022] The HMF pool includes a hollow fiber ultrafiltration membrane assembly 13 , an aeration system 14 , an HMF pool sludge collecting hopper 15 and an HMF pool water production pipeline 16 .

[0023] The electrodialysis device includes an electrodialysis anion exchange membrane 17, an electrodialysis cation exchange membrane 18, an electrodialysis dilute chamber 19, an electrodialysis concentrate chamber 20, an electrodialysis concentrate chamber outlet pipe 21, an electrodialysis dilute chamber outlet pipe 22, an electrodialysis fresh water tank 23, an electrodialysis concentrate tank 24, an electrodialysis anode chamber 25, an electrodialysis cathode chamber 26 and a mud conveying pipeline 27. The electrodialysis concentrate chamber 20 is connected to the electrodialysis concentrate tank 24 via the electrodialysis concentrate chamber outlet pipe 21, and the electrodialysis dilute chamber 19 is connected to the electrodialysis dilute chamber tank 23 via the electrodialysis dilute chamber outlet pipe 22.

[0024] The treatment system of this utility model is designed for the RO concentrated water of the printing and dyeing wastewater membrane deep treatment process. The RO concentrated water of the printing and dyeing wastewater has the characteristics of high COD, high chroma, high hardness and high salt content, and the conductivity is usually 12 mS·cm -1 ~18 mS·cm -1 Floating within the range, COD is 300 mg·L -1 ~800 mg·L -1 , hardness is 100 mg·L -1 ~200 mg·L -1 , the chromaticity is 700 degrees to 1800 degrees.

[0025] In step one, RO concentrate from printing and dyeing wastewater enters the electroflocculation tank through the electroflocculation inlet pipe 1. The water flows upward from the bottom. Under the action of direct current, the anodes of the electroflocculation cathode plates 2 and 3 are corroded, producing metal ions. These ions undergo a series of hydrolysis reactions, forming complexes and hydroxides that drive pollutant sedimentation. Simultaneously, charged pollutant particles migrate in the electric field, where their partial charge is neutralized by the electrodes, leading to destabilization and coagulation. The electroflocculation tank can remove 60% to 90% of COD and color, or even higher. It also significantly removes calcium and magnesium ions, with optimal removal rates exceeding 90%.

[0026] In step 2, under the action of electric flocculation, the water quality of the printing and dyeing wastewater is optimized, and sludge and a large amount of suspended matter are produced along with complexation. Under the action of natural sedimentation, part of the sludge falls into the sludge collecting hopper 4 of the flocculation tank, and the water flows from bottom to top from the electric flocculation outlet 5 to the electric flocculation outlet channel 6, and enters the inclined tube sedimentation tank through the water inlet 7 of the inclined tube sedimentation tank.

[0027] In step three, the printing and dyeing wastewater flows upward through the inclined tube sedimentation tank. As the wastewater flows upward through the inclined tube 8, suspended solids and sludge in the water fall onto the inclined tube and, following the slope of the inclined tube, fall into the sludge collecting hopper 9 of the inclined tube sedimentation tank. After passing through the inclined tube area, the suspended solids in the water are largely removed. The clean water continues to flow upward to the outer wall of the inclined tube sedimentation tank sump 10, flows into the sump through the sump inlet hole 11 on the upper side of the sump, and flows along the sump through the inclined tube sedimentation tank outlet 12 into the high-intensity submerged membrane filtration (HMF) tank.

[0028] In step 4, the printing and dyeing wastewater passes through the screening effect of the hollow fiber ultrafiltration membrane assembly 13 in the HMF pool, and the remaining suspended matter in the water can be basically completely removed. Under the action of negative pressure suction, water molecules penetrate from the surface of the membrane filaments to the inside of the membrane filaments, and the pollutants are retained on the surface of the membrane filaments. Under the action of the HMF aeration system 14, the pollutants on the surface of the membrane filaments are washed away by water vapor, slowing down the accumulation rate of membrane pollution. After precipitation, the pollutants fall into the HMF pool sludge hopper 15. Clean water enters the electrodialysis from the HMF pool water production pipeline 16. HMF can reduce the turbidity of wastewater to below 1 NTU.

[0029] Step five, after the printing and dyeing wastewater enters the electrodialysis device, under the action of electric current, the anions in the water pass through the anion exchange membrane 17, and the cations pass through the cation exchange membrane 18, and the anions and cations are continuously transferred from the electrodialysis dilution chamber 19 to the electrodialysis concentration chamber 20. The inorganic salt concentration of the water in the dilution chamber continues to decrease, and finally the water outlet of the electrodialysis concentration chamber concentrates a large amount of inorganic salts and can be directly reused as concentrated brine; the dilution chamber has a low inorganic salt content and excellent water quality, and can be reused as a freshwater resource. After the wastewater is desalinated and concentrated, the water produced by the electrodialysis concentration chamber 20 enters the electrodialysis concentrated water tank 24 along the electrodialysis concentration chamber outlet pipe 21, and the water produced by the electrodialysis dilution chamber 19 enters the electrodialysis dilution chamber water tank 23 along the electrodialysis dilution chamber outlet pipe 22.

[0030] Step 6: The sludge collected from the electric flocculation tank, the inclined tube sedimentation tank and the HMF tank is uniformly transported to the sludge treatment device area through the sludge transport pipeline 27.

[0031] Among them, electrocoagulation is a water treatment technology that utilizes electrochemical principles. Using alloy metals such as aluminum and iron as the main electrodes, it applies pulsed high voltage to generate an electrochemical reaction, converting electrical energy into chemical energy. This method produces metal cationic flocculants that separate pollutants from the water through coagulation, flotation, reduction, and oxidative decomposition, achieving the goal of purifying the water.

[0032] Among them, electrocoagulation technology is an effective wastewater treatment method, highly efficient in removing organic matter from water. This technology uses electrolysis to generate highly oxidizing free radicals and cations. These active substances react with organic matter, thereby reducing COD, BOD, and other organic indicators in the water. This technology has applications in both oilfield wastewater and papermaking wastewater.

[0033] Among them, electrocoagulation is used to remove calcium and magnesium ions from water, and its removal effect is significant in the field of electric field circulating cooling water. Increasing the current density and extending the electrolysis time can improve the efficiency of hardness removal. In addition, alkaline conditions are more conducive to the removal of calcium and magnesium ions than acidic and neutral conditions. RO concentrate from printing and dyeing wastewater has a high pH, ​​which is advantageous for hardness removal.

[0034] The electroflocculation device itself has a sedimentation function. To ensure the effective removal of flocculants and suspended solids in the water, a sedimentation tank is connected after the electroflocculation device. This secondary sedimentation of the wastewater effectively removes suspended solids. The sedimentation tank is not limited to a specific type and can be a conventional sedimentation tank or an inclined tube sedimentation tank. The inclined tube sedimentation tank was chosen for this design.

[0035] The HMF process, developed based on MBR, centers on hollow fiber membrane separation technology. This innovative purification and separation technology utilizes pressure differentials as a driving force and has been widely used in various fields, including printing and dyeing, chemicals, medicine, and biology. The HMF membrane system utilizes negative pressure suction filtration. After undergoing front-end treatment, wastewater enters the membrane tank. A suction pump operates to push the wastewater through the outer walls of the hollow fiber membranes and into the interior. Filtered water flows out from the interior, while pollutants are trapped on the membrane surface. The membrane components can be selected from the BP series fabric-reinforced polyvinylidene fluoride (PVDF) hollow fiber membranes produced by Zhejiang Jinmo Environmental Technology Co., Ltd. These membranes have an average pore size of 0.03 μm and feature high tensile strength, long service life, and excellent effluent quality. HMF treatment significantly reduces COD, color, turbidity, and suspended solids in wastewater.

[0036] Among them, this system uses the HMF process to further remove suspended matter in the effluent from the sedimentation tank to ensure the smooth operation of the electrodialysis process.

[0037] Electrodialysis technology utilizes the potential difference in a DC electric field to force anions and cations in the solution through a selectively permeable anion and cation exchange membrane, thereby transferring inorganic salt ions from the freshwater chamber to the concentrated water chamber, achieving the purpose of desalination and concentration of the solution salt. This system uses an electrodialysis device to extract and concentrate salt from RO concentrate after electrocoagulation, sedimentation tanks, and HMF treatment, ultimately enabling the reuse of RO concentrate.

[0038] The advantages of this utility model are as follows:

[0039] 1. Further process treatment of RO concentrated water from printing and dyeing wastewater avoids the waste of inorganic salt resources and water resources in the wastewater, reduces the biochemical treatment burden on the sewage treatment plant after the RO concentrated water is directly discharged to the lower-level sewage treatment plant, and reduces the risk of environmental pollution;

[0040] 2. The combined process of electrocoagulation and HMF as the core is used to improve the quality of RO concentrated water, which has the advantages of simple process flow, convenient operation and high treatment efficiency.

[0041] 3. Using electrodialysis technology as the core salt recycling system to replace the MVR evaporation system can greatly reduce the energy consumption during process operation and improve the resource recycling rate. The electrodialysis fresh water is reused as water resources, the concentrated water is a high-concentration salt solution, and the inorganic salt is reused in the form of liquid;

[0042] 4. The system achieves zero discharge of printing and dyeing wastewater, which has positive benefits for industry development and environmental survival.

[0043] Although the embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater, characterized by: It includes an electric flocculation tank, an inclined tube sedimentation tank, a high-intensity submerged membrane filtration tank and an electrodialysis device which are arranged in sequence; The electrocoagulation tank includes an electrocoagulation tank water inlet pipe, an electrocoagulation cathode plate, an electrocoagulation anode plate, an electrocoagulation mud collecting hopper, an electrocoagulation water outlet and an electrocoagulation water outlet channel, wherein the electrocoagulation tank water inlet pipe is located at the lower left of the electrocoagulation tank, the electrocoagulation water outlet is located at the upper right of the electrocoagulation tank, and the electrocoagulation cathode plate and the electrocoagulation anode plate are staggered. The high-intensity submerged membrane filtration pool includes a hollow fiber ultrafiltration membrane component, an aeration system, an HMF pool mud collecting hopper and an HMF pool water production pipeline.

2. A short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater according to claim 1, characterized in that: The inclined tube sedimentation tank includes an inclined tube sedimentation tank water inlet, an inclined tube, an inclined tube sedimentation tank mud collecting hopper, an inclined tube sedimentation tank water collecting trough and an inclined tube sedimentation tank water outlet. Water collecting trough water inlet holes are distributed on both sides of the inclined tube sedimentation tank water collecting trough. The water inlet of the inclined tube sedimentation tank is located at the lower left side of the inclined tube sedimentation tank, and the water outlet of the inclined tube sedimentation tank is located at the upper right side of the inclined tube sedimentation tank.

3. A short-process and efficient RO concentrated water treatment system for printing and dyeing wastewater according to claim 1, characterized in that: The electrodialysis device includes an electrodialysis anion exchange membrane, an electrodialysis cation exchange membrane, an electrodialysis dilute chamber, an electrodialysis concentrate chamber, an electrodialysis concentrate chamber outlet pipe, an electrodialysis dilute chamber outlet pipe, an electrodialysis fresh water tank, an electrodialysis concentrate water tank, an electrodialysis anode chamber, an electrodialysis cathode chamber and a mud conveying pipeline. The electrodialysis concentrate chamber is connected to the electrodialysis concentrate water tank via the electrodialysis concentrate chamber outlet pipe, and the electrodialysis dilute chamber is connected to the electrodialysis dilute chamber water tank via the electrodialysis dilute chamber outlet pipe.

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