Method and device for recycling waste water containing chlorobenzene from solution polymerization rubber

Abstract

The present application belongs to the technical field of wastewater treatment, and particularly relates to a method and device for recycling solution polymerization rubber wastewater containing chlorobenzene. The method for recycling solution polymerization rubber wastewater containing chlorobenzene comprises the following steps: homogenization, i.e. introducing the solution polymerization rubber wastewater containing chlorobenzene into a homogenization tank; oxidation air flotation, i.e. introducing the treated wastewater and the oxidized wastewater into two-stage UV generators for oxidation treatment, ultrasonic treatment, and recycling; separating the treated residue water through a basket strainer, discharging the water up to the standard, and discharging the tail gas up to the standard; clarification buffering; pretreatment for recycling, i.e. treating the suspended solids in the water in the buffer tank; recycling treatment, i.e. treating the water after the ultrafiltration unit, recycling the produced water, and introducing the concentrated water into a first-stage UV generator for treatment. The present application provides a method for recycling solution polymerization rubber wastewater containing chlorobenzene, which is environmentally friendly in the treatment process, has no harmful gas emission, has good water quality, has high water production rate, and has concentrated water organic matter up to the standard. The present application also provides a recycling device, which is stable in operation.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, specifically relating to a method and apparatus for reusing chlorinated benzene wastewater from solution polymerization of rubber. Background Technology

[0002] Chlorobenzene is commonly used as an intermediate and solvent in dyes, pharmaceuticals, pesticides, and organic synthesis. It is a colorless, transparent, volatile liquid with an almond-like odor and is toxic to the environment and human health. Wastewater containing chlorobenzene can pollute water bodies, soil, and the atmosphere. However, due to its excellent properties, it is often used as an additive or solvent in rubber production for solution polymerization. Even after chlorobenzene recovery, some still transfers to rubber wastewater, with concentrations reaching over 200 mg / L. This chlorobenzene-containing wastewater must undergo environmentally friendly treatment, and the environmental impact of chlorobenzene gas emissions must be considered.

[0003] In rubber production processes, solution polymerization and emulsion polymerization are common. Compared to emulsion polymerization, which uses more additives and involves the addition of acids, alkalis, or salts during latex coagulation, leads to greater difficulty in treating the organic matter in the wastewater. The wastewater often has a high salt content and contains latex and rubber particles. Generally, after removing residual rubber particles via flotation, the wastewater is mixed with other wastewater in a wastewater treatment plant and treated with activated sludge for reuse. Solution polymerization typically uses fewer acids, alkalis, and salts, resulting in relatively lower salt content and the absence of latex. Reuse after removing organic matter is relatively easier. However, the presence of rubber particles increases the difficulty of reuse.

[0004] If chlorobenzene-containing wastewater is directly discharged into a wastewater treatment plant, it will inevitably affect the activated sludge, leading to substandard wastewater discharge. Although activated sludge capable of degrading chlorobenzene can be cultivated over time, the chlorobenzene concentration becomes unstable during production fluctuations, further impacting the wastewater treatment plant sludge. Therefore, chlorobenzene-containing wastewater must undergo separate treatment to remove its toxicity to microorganisms before being discharged into the wastewater treatment plant. Consequently, it is difficult to comprehensively consider the reuse of chlorobenzene-containing wastewater after wastewater treatment.

[0005] When chlorobenzene in wastewater is difficult to treat directly by physical and biological methods, advanced oxidation technologies such as Fenton oxidation, photocatalytic oxidation, and high-temperature wet catalytic oxidation are used. These technologies can pre-treat or deeply treat chlorobenzene-containing wastewater, but the treatment cost is usually high.

[0006] Patent CN101774736B discloses a deep treatment process for chloroprene rubber industrial wastewater. It mainly includes four steps: coagulation and sedimentation, multi-media filtration, ultrafiltration, and reverse osmosis. The advantages of this invention are: it can effectively remove the adverse effects of pollutants in chloroprene rubber industrial wastewater on ultrafiltration and reverse osmosis membranes at a relatively low cost, enabling the wastewater to meet the reverse osmosis feed water quality requirements and undergo desalination via reverse osmosis. The deeply treated wastewater can then be reused as high-quality industrial water for boiler feedwater, process water, etc., ensuring the stable, continuous, and reliable industrial operation of the deep treatment and reuse system, achieving a win-win situation for both the economy and the environment. This invention uses coagulation and sedimentation to treat suspended solids. However, in actual rubber wastewater treatment, it has been found that low concentrations of flocculants and coagulants have poor flocculation effects, even with high concentrations. Most of the colloidal particles cannot be removed by coagulation and sedimentation, resulting in severe clogging of subsequent multi-media and ultrafiltration processes. The added reagents themselves also have a clogging effect on subsequent ultrafiltration and reverse osmosis. At the same time, this invention lacks organic matter removal facilities, which will also cause fouling and clogging of subsequent reverse osmosis processes, which is not conducive to stable operation.

[0007] Patent CN102358650B discloses a method and apparatus for the deep purification and reuse of recalcitrant organic industrial wastewater. This invention targets water discharged after conventional biochemical treatment of recalcitrant organic industrial wastewater such as coking wastewater and dyeing wastewater. It combines advanced oxidation technology, membrane technology, and industrial water treatment technology to provide a method and apparatus for the deep treatment and reuse of recalcitrant organic industrial wastewater after conventional biochemical treatment, achieving zero discharge of industrial wastewater. The treatment method and apparatus include the following steps: 1) media filtration; 2) self-cleaning filtration; 3) COD decomposer; 4) visible light photocatalytic oxidation; 5) ultrafiltration membrane section; 6) reverse osmosis membrane section; ultimately producing high-quality water that can be reused in production to replace fresh water. Although the patent provides a reuse process that does not require biological treatment, the direct use of media filtration and self-cleaning is not suitable for wastewater containing rubber particles. This leads to the clumping of filter media and sticking of filter discs, resulting in a significant decrease in filtration efficiency. In addition, the COD decomposer has a low oxidation effect, and the visible light catalytic oxidation uses a honeycomb titanium dioxide catalyst, which is expensive and loses its catalytic effect after the surface is contaminated. Therefore, it is not suitable for reuse in treating rubber wastewater containing rubber particles.

[0008] In summary, the following technical problems exist in the current reuse of wastewater from solution-polymerized chlorinated benzene rubber:

[0009] 1. Wastewater is toxic to microorganisms and should not be directly discharged into the sewage treatment plant. It should be treated with activated sludge and then reused after comprehensive consideration.

[0010] 2. Chlorobenzene volatilizes during the wastewater treatment process, requiring a separate waste gas treatment facility.

[0011] 3. The wastewater treatment process is lengthy, involves many types of chemicals, requires large dosages, results in high operating costs, increases the salt content of the wastewater, makes reuse more difficult, and is also prone to fouling the reverse osmosis membrane.

[0012] 4. The wastewater contains additives and colloidal particles, which are prone to clumping and are difficult to reuse. Traditional air flotation methods are not thorough in removing colloidal particles and cause chlorobenzene to leak out, increasing the burden on subsequent tail gas treatment.

[0013] 5. The colloidal particles in the water contain chlorobenzene, which poses a health risk to the personnel handling the process.

[0014] 6. Organic matter in the reused concentrated wastewater must be treated at a wastewater treatment plant or a new concentrated wastewater treatment facility must be built to meet the standards. Summary of the Invention

[0015] The technical problem to be solved by this invention is to provide a method for recycling chlorinated benzene wastewater from solution polymerization of rubber. The treatment process is environmentally friendly, with no harmful gases escaping, producing high-quality water with a high water production rate, and the concentrated water meeting the organic matter standards. This invention also provides a recycling device that operates stably.

[0016] The method for reusing chlorinated benzene wastewater from solution polymerization of rubber according to the present invention includes the following steps:

[0017] (1) Homogenization: The chlorinated benzene wastewater from the solution-polymerized rubber is introduced into the homogenizing tank and air is introduced. A one-way air inlet and an exhaust gas outlet pipeline are installed at the top of the homogenizing tank.

[0018] (2) Oxidative flotation: The treated wastewater, oxidized wastewater, chlorobenzene waste gas and reused concentrated water are fed into a two-stage UV generator under the action of oxidant for oxidation treatment. The treated wastewater enters the oxidation tank, where wastewater and waste gas are further treated under the synergistic action of ultrasound, and the cycle continues. At the same time, the sludge and water treated by the sludge scraper on the oxidation tank are separated by a basket filter. The sludge is disposed of in a conventional manner, the water is discharged after meeting the standards, and the purified waste gas is discharged after meeting the standards.

[0019] (3) Clarification and buffering: Wastewater treated by the oxidation tank enters the buffer tank;

[0020] (4) Reuse pretreatment: The water in the buffer tank continues to enter the multi-media filter to treat suspended solids. The backwash water of the multi-media filter enters the homogenization tank. The water after multi-media treatment enters the ultrafiltration unit to further remove particulate matter in the multi-media effluent. The backwash water of the ultrafiltration is returned to the buffer tank.

[0021] (5) Reuse treatment: After the water is treated by the ultrafiltration unit, a reducing agent is added to remove the residual oxidant before it enters the reverse osmosis unit. The product water is reused, and the concentrate continues to enter the first-stage UV generator for treatment.

[0022] The homogenizing tank in step (1) is a conventional homogenizing tank, and the hydraulic residence time in the wastewater homogenization is 1 to 10 hours; the oxidation tank in step (2) is preferably made of polytetrafluoroethylene, polyethylene, or lined with anti-corrosion material, and the wastewater enters the oxidation tank. The hydraulic residence time is 1 to 4 hours based on the influent; the oxidation reaction temperature is 45 to 50°C, and the control method is preferably but not limited to ultraviolet power adjustment.

[0023] In step (2), the oxidant is hydrogen peroxide; the ratio of the dry basis dosage of the oxidant to the COD of the influent is 2:1 to 8:1.

[0024] In step (2), an ultrasonic generator is installed at the bottom of the oxidation tank, including an ultrasonic power supply and a transducer. The ultrasonic frequency is preferably, but not limited to, 20–80 kHz, and frequency sweep operation is preferred. The installed power is preferably, but not limited to, 100–500 W / m. 3 .

[0025] When the wastewater treated by the oxidation tank in step (3) enters the buffer tank, the residual oxidant is 10-100 mg / L.

[0026] In step (2), when the homogenized wastewater and the oxidized wastewater are fed into the UV generator together, the flow rate of the oxidized wastewater is 5 to 15 times the flow rate of the homogenizing tank booster pump.

[0027] In step (2), the circulating pump is preferably a gas-water mixing pump. The flow rate of the oxidation tank outlet and the flow rate of the booster pump are designed. The gas-water ratio of waste gas and waste water is preferably 1:20 to 1:100. The air intake is controlled by the fixed one-way air inlet of the homogenizing tank.

[0028] In step (2), the scum and part of the effluent enter the basket filter through the scum discharge port. The basket filter is preferably filtration precision of 10 to 100 μm.

[0029] The reducing agent in step (5) is sodium bisulfite, with a concentration of 5–20 mg / L.

[0030] The solution polymerization rubber chlorinated benzene wastewater recycling device consists of: a homogenizing tank connected to an oxidation tank; the oxidation tank connected to a buffer tank via an outlet three; the buffer tank connected to a multi-media filter; the multi-media filter connected to an ultrafiltration unit; the ultrafiltration unit connected to a reverse osmosis unit; and the homogenizing tank equipped with a wastewater inlet pipe, a waste gas outlet pipe, an air inlet, and a homogenizing tank outlet.

[0031] The homogenizing tank is connected to the homogenizing tank lift pump through the homogenizing tank outlet. The homogenizing tank lift pump is connected to the circulation pump. The circulation pump is connected to the first-stage UV generator. The first-stage UV generator is connected to the second-stage UV generator. The second-stage UV generator is connected to the oxidation tank through the second outlet of the oxidation tank. An oxidant inlet pipe and an exhaust gas circulation pipe are installed between the homogenizing tank lift pump and the circulation pump. The exhaust gas circulation pipe is connected to the exhaust gas outlet pipeline.

[0032] The oxidation tank is equipped with a slag scraper and an ultrasonic generator. The oxidation tank is equipped with oxidation tank outlet 1, oxidation tank outlet 2, oxidation tank outlet 3, and exhaust gas outlet. Oxidation tank outlet 1 is connected to the outlet of the homogenization tank booster pump.

[0033] The oxidation tank is connected to the basket filter, and the basket filter is connected to the scum collection device.

[0034] A backwash water pipe is installed between the homogenizing tank and the multi-media filter; a backwash water pipe is installed between the ultrafiltration unit and the buffer tank; and a reducing agent inlet pipe is installed on the pipeline between the ultrafiltration unit and the reverse osmosis unit.

[0035] The reverse osmosis unit is connected to both the recycled water recovery device and the wastewater treatment plant concentrate recovery pipe; the wastewater treatment plant concentrate recovery pipe is connected to the circulation pump.

[0036] The basket filter is equipped with an external drain pipe.

[0037] A slag scraper is installed at the top inside the oxidation tank, designed according to the conventional air flotation slag scraper.

[0038] The UV generator consists of a power supply, a UV lamp, and a reaction tube. The UV lamp in the primary UV generator is capable of producing UV light with a wavelength of 200–400 nm; a medium-voltage UV lamp is preferred, and the preferred installation power is 300–3000 W / m. 3 The secondary UV generator uses a UV lamp capable of producing ultraviolet light with a wavelength less than 200nm. Low-pressure UV lamps are preferred, with an installation power of 100–700W / m². 3 The reaction tube is divided into a quartz sleeve area and a wastewater area. The quartz sleeve is preferably made of quartz to isolate the UV lamp tube from the wastewater medium. The wastewater and waste gas reaction area is preferably made of, but not limited to, quartz, PTFE, or polyethylene. The effective volume of the primary UV generator reaction tube is preferably calculated based on the influent hydraulic residence time of 30–120 s. The effective volume of the secondary UV generator reaction tube is preferably calculated based on the influent hydraulic residence time of 150–600 s. The power supply is matched to the UV lamp.

[0039] The hydraulic retention time of the buffer tank, calculated based on the influent, is preferably 1 to 2 hours.

[0040] The multi-media filter preferably uses one or more of the following media: quartz sand, anthracite, activated carbon, magnetite, garnet, porous ceramics, and plastic balls. The preferred filtration rate is 5–10 m / h. The multi-media filter preferably has a water production rate of over 95%. Backwash influent uses the multi-media filter effluent, and the backwash effluent is returned to the homogenization tank.

[0041] The ultrafiltration unit is a conventional wastewater reuse ultrafiltration unit. According to conventional design, the water production rate is preferably 85% to 95%. The backwash influent uses the ultrafiltration effluent, and the backwash effluent is returned to the buffer tank.

[0042] The reverse osmosis unit is a conventional wastewater reuse reverse osmosis unit, designed according to conventional methods, with an optimal water production rate of 75% to 85%.

[0043] Specifically, the method for reusing chlorinated benzene wastewater from solution polymerization of rubber includes the following steps:

[0044] (1) Homogenization: Wastewater enters the homogenizing tank of the present invention. The upper part of the homogenizing tank is provided with a one-way air inlet and a waste gas outlet pipeline, and the lower part is provided with a water outlet. The purpose of this step is to homogenize the wastewater and ensure that no chlorinated benzene waste gas escapes from the homogenizing tank.

[0045] (2) Oxidative Flotation: After the effluent from the homogenizing tank and the effluent from the bottom outlet of the oxidation tank are mixed, an oxidant is added and then mixed with the chlorobenzene waste gas from the top of the homogenizing tank before entering a two-stage UV generator for oxidation treatment. At a certain temperature, the organic matter in the wastewater of the first-stage UV generator is in an oxidized and excited state after being irradiated by high-intensity ultraviolet light. In particular, chlorobenzene can be photolyzed. At the same time, the oxidant is decomposed by high-intensity ultraviolet light to produce hydroxyl radicals and nascent oxygen, which oxidizes and decomposes organic matter such as chlorobenzene in both the gas phase and the water phase, thus purifying the waste gas and wastewater. Simultaneously, suspended solids in the wastewater adhere together with the nascent oxygen microbubbles generated by the oxidant and the carbon dioxide microbubbles generated by the oxidation of organic matter, eliminating the stability of the suspended solids and making them easy to remove by flotation. The low-intensity ultraviolet light of the second-stage UV generator further converts the nascent oxygen generated by the first-stage UV reactor into ozone, which improves the oxidizing power and further degrades organic matter, and further promotes the adhesion of small bubbles to the suspended solids. The oxidation effect of the two-stage UV generator and the adhered bubbles also perform surface oxidation on the suspended solids, making them less prone to agglomeration and gelation. The effluent from the secondary UV generator enters the oxidation tank, where, under the synergistic effect of ultrasound, the oxidant, strong free radicals, and ozone in the water thoroughly degrade organic matter. Simultaneously, suspended solids are removed through efficient flotation caused by the adhesion of small bubbles, ultrasonic cavitation, and the release of purified exhaust gas pressure. The oxidant dosage is controlled, and the water is circulated through the UV generator to ensure effective treatment of chlorobenzene and other organic matter.

[0046] The effluent from which organic matter and suspended solids have been removed enters the subsequent steps through the upper outlet of the oxidation tank. A sludge scraper is installed at the top of the oxidation tank; sludge and effluent enter a basket filter for separation. The scum is disposed of using standard methods, while the effluent meets discharge standards. Purified exhaust gas is discharged from the top of the oxidation tank after meeting discharge standards. The purpose of this step is to purify waste gas, remove organic matter such as chlorobenzene from wastewater, remove suspended solids, and remove organic matter from the concentrated wastewater for subsequent reuse, creating conditions for reuse and ensuring that the discharged wastewater meets standards.

[0047] (3) Clarification and buffering: The effluent from the oxidation tank enters the buffer tank, which serves as a buffer for subsequent reuse.

[0048] (4) Reuse Pretreatment: The effluent from the buffer tank enters a conventional multi-media filter to further remove the trace amounts of suspended solids carried over with the effluent from the oxidation tank. The multi-media effluent then enters a conventional ultrafiltration unit, and the multi-media backwash water enters a homogenization tank. Ultrafiltration further removes particulate matter from the multi-media effluent, and the ultrafiltration backwash water is returned to the buffer tank. This step serves as pretreatment for subsequent reverse osmosis. The backwash water from both the multi-media filter and ultrafiltration is returned to this invention and not discharged externally to improve the water production rate. The treatment process controls the residue of the oxidant without the need for additional bactericides.

[0049] (5) Reuse treatment: After adding a reducing agent to remove residual oxidant, the ultrafiltration effluent enters the conventional reverse osmosis unit for reuse, and the concentrate enters the front end of the first-stage UV reactor of this invention for treatment.

[0050] The wastewater recycling device for solution-polymerized rubber containing chlorinated benzene of the present invention is implemented as follows:

[0051] Wastewater first enters a homogenizing tank for buffering. The effluent from the homogenizing tank is mixed with the effluent from the bottom of the oxidation tank, then an oxidant is added. This mixture is then mixed with chlorobenzene exhaust gas from the top of the homogenizing tank before entering a two-stage UV generator for oxidation treatment. In the first-stage UV generator, organic matter such as chlorobenzene in both the gaseous and aqueous phases is oxidized and decomposed. Simultaneously, suspended solids adhere to the microbubbles generated by the reaction, making them easily removable by flotation. In the second-stage UV generator, low-intensity ultraviolet light further converts the nascent oxygen in the effluent from the first-stage UV reactor into ozone, increasing oxidizing power and further degrading organic matter. It also further enhances the adhesion and oxidation of suspended solids through microbubble adhesion, preventing clumping and agglomeration. The effluent from the second-stage UV generator enters the oxidation tank, where, under the synergistic effect of ultrasound, the oxidant, strong oxidizing free radicals, and ozone in the effluent continue to efficiently degrade organic matter. Simultaneously, suspended solids are removed through efficient flotation due to the adhesion of microbubbles, ultrasonic cavitation, and the release of purified exhaust gas pressure. The influent and effluent from the two-stage UV generator circulate in the lower part of the oxidation tank, continuously degrading organic matter. The purified exhaust gas is discharged from the top; scum generated by air flotation in the oxidation tank enters a basket filter along with the scum water. The filtered scum is disposed of conventionally, and the effluent meets organic matter discharge standards. The effluent from the oxidation tank is discharged from the upper middle part into a buffer tank. Residual suspended solids in the buffer tank are further removed by a multi-media filter before entering the ultrafiltration unit. The effluent from the ultrafiltration unit undergoes reverse osmosis desalination treatment; the desalinated permeate is reused, and the concentrate is returned to the primary UV reactor of this invention. Backwash water from the multi-media unit is returned to the homogenizing tank, and backwash water from the ultrafiltration unit is returned to the buffer tank to improve the wastewater reuse rate.

[0052] This invention employs a two-stage UV generator. The first-stage UV generator uses high-intensity ultraviolet light emitted from a medium-pressure UV fan. This light causes pollutants to absorb the ultraviolet light and enter a form that is easily degradable. Simultaneously, it catalyzes hydrogen peroxide to generate hydroxyl radicals. The second-stage UV generator further utilizes the nascent oxygen in the effluent from the first-stage UV generator to produce ozone, thus efficiently degrading pollutants.

[0053] This invention utilizes the synergistic oxidation effects of ultrasound, hydrogen peroxide, ozone, and hydroxyl radicals to efficiently remove organic matter, significantly reducing the organic matter content in the influent of the reuse unit, ensuring the operating efficiency of the reuse unit, and guaranteeing that the discharged water meets standards. No catalysts or flocculants such as iron or aluminum salts are added during the organic matter removal process, avoiding contamination of subsequent reverse osmosis processes by these agents.

[0054] The solution polymerization rubber chlorinated benzene wastewater reuse method of this invention does not increase the salt content of the wastewater during the treatment process, except for a small amount of reducing agent. The residual oxidant and ozone from the oxidation process have bactericidal effects, eliminating the need to add chlorine-containing bactericides before ultrafiltration and thus not increasing the subsequent desalination burden. The concentrated wastewater undergoes organic matter treatment within this invention, eliminating the need for additional organic matter treatment facilities.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (1) In the method of the present invention, the waste gas is introduced into the wastewater treatment pipeline, and the wastewater and waste gas are treated by the same device, which saves the investment in waste gas and land occupation, and ensures that no harmful gas escapes during the reuse process; the invention process is compact and occupies a small area; the reused concentrated water is treated to meet the standards in the present invention, and no new concentrated water treatment facilities are required.

[0057] (2) This invention uses high-intensity ultraviolet light, low-intensity ultraviolet light in conjunction with oxidant, ozone and ultrasound, resulting in high advanced oxidation efficiency, thorough removal of chlorobenzene characteristic pollutants, ensuring efficient removal of concentrated organic matter in water, and ensuring that the organic matter in the effluent meets the standards.

[0058] (3) The present invention uses microbubbles generated in the two-stage UV generator to make the suspended matter in a state that is easy to be removed by air flotation and is not easy to agglomerate and gel. The purified waste gas, the decomposed oxidant, and the ozone generated by the secondary UV generator produce a synergistic and efficient air flotation effect under the use of ultrasound, effectively removing suspended particles, ensuring the removal rate of particles and other suspended matter in wastewater, and further ensuring the operating efficiency of the reuse device.

[0059] (4) This invention does not add catalysts or flocculants such as iron salts and aluminum salts during the removal of organic matter, thus avoiding the contamination of subsequent reverse osmosis by such agents.

[0060] (5) The oxidant of the present invention does not increase the salt content of wastewater, does not require an acid or alkaline pH environment, and does not increase the salt content of wastewater except for a small amount of reducing agent during the treatment process. The oxidant not consumed in the oxidation process has a bactericidal effect. There is no need to add chlorine-containing bactericides before ultrafiltration, and it does not increase the subsequent desalination burden.

[0061] (6) The oxidation cost of chlorinated benzene wastewater treatment process is high. After treatment, it is not discharged but reused. The method of the present invention improves the water resource utilization rate and improves the economic efficiency of wastewater operation costs.

[0062] (7) The recycled concentrated water is treated in this invention, and the organic matter in the wastewater meets the standards; the scum discharged from the oxidation tank does not contain chlorobenzene, and the treatment process is more environmentally friendly. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the structure of the solution polymerization rubber chlorinated benzene wastewater recycling device of the present invention;

[0064] In the diagram: 1. Homogenizing tank; 2. Oxidizing tank; 3. Sludge scraper; 4. Scum removal device; 5. Buffer tank; 6. Multi-media filter; 7. Ultrafiltration unit; 8. Reverse osmosis unit; 9. Reclaimed water recovery device; 10. Wastewater treatment concentrate recovery pipe; 11. Primary UV generator; 12. Exhaust gas circulation pipe; 13. Oxidant input pipe; 14. Wastewater inlet pipe; 15. Exhaust gas outlet pipe; 16. Air inlet; 17. Tail gas outlet; 18. Backwash water pipe one; 19. Backwash water pipe two; 20. Reducing agent input pipe; 21. Ultrasonic generator; 22. Homogenizing tank lift pump; 23. Circulation pump; 24. Homogenizing tank outlet; 25. Oxidizing tank outlet one; 26. Oxidizing tank outlet two; 27. Oxidizing tank outlet three; 28. Basket filter; 29. ​​External drainage pipe; 30. Secondary UV generator. Detailed Implementation

[0065] The embodiments all use the solution polymerization rubber chlorinated benzene wastewater recycling device of the present invention, which further illustrates the beneficial effects of the present invention.

[0066] like Figure 1 As shown, the solution polymerization rubber chlorinated benzene wastewater recycling device consists of: a homogenizing tank 1 connected to an oxidation tank 2; the oxidation tank 2 connected to a buffer tank 5 via an oxidation tank outlet 27; the buffer tank 5 connected to a multi-media filter 6; the multi-media filter 6 connected to an ultrafiltration unit 7; the ultrafiltration unit 7 connected to a reverse osmosis unit 8; and the homogenizing tank 1 is equipped with a wastewater inlet pipe 14, a waste gas outlet pipe 15, an air inlet 16, and a homogenizing tank outlet 24.

[0067] Homogenizing tank 1 is connected to homogenizing tank lift pump 22 via homogenizing tank outlet 24. Homogenizing tank lift pump 22 is connected to circulation pump 23. Circulation pump 23 is connected to primary UV generator 11. Primary UV generator 11 is connected to secondary UV generator 30. Secondary UV generator 30 is connected to oxidation tank 2 via oxidation tank outlet 26. Oxidizing agent inlet pipe 13 and waste gas circulation pipe 12 are provided between homogenizing tank lift pump 22 and circulation pump 23. Waste gas circulation pipe 12 is connected to waste gas outlet pipeline 15.

[0068] The oxidation tank 2 is equipped with a slag scraper 3 and an ultrasonic generator 21. The oxidation tank 2 is equipped with an oxidation tank outlet 1 25, an oxidation tank outlet 26, an oxidation tank outlet 3 27, and a tail gas outlet 17. The oxidation tank outlet 1 25 is connected to the outlet of the homogenizing tank lift pump 22.

[0069] Oxidation tank 2 is connected to basket filter 28, and basket filter 28 is connected to scum device 4;

[0070] A backwash water pipe 18 is installed between the homogenizing tank 1 and the multi-media filter 6; a backwash water pipe 29 is installed between the ultrafiltration unit 7 and the buffer tank 5; and a reducing agent inlet pipe 20 is installed on the pipeline between the ultrafiltration unit 7 and the reverse osmosis unit 8.

[0071] The reverse osmosis unit 8 is connected to both the recycled water recovery device 9 and the wastewater treatment plant concentrate recovery pipe 10; the wastewater treatment plant concentrate recovery pipe 10 is connected to the circulating pump 23.

[0072] An external drain pipe 29 is provided on the basket filter 28.

[0073] All examples employ the method for treating chlorinated benzene-containing wastewater from solution polymerization of rubber according to the present invention, including the following steps:

[0074] (1) Homogenization: The chlorinated benzene wastewater from the solution-polymerized rubber is introduced into a homogenizing tank and homogenized by air and exhaust gas.

[0075] (2) Oxidative flotation: The treated wastewater, oxidized wastewater, chlorobenzene waste gas and reused concentrated water are fed into a two-stage UV generator under the action of oxidant for oxidation treatment. The treated wastewater enters the oxidation tank, where wastewater and waste gas are further treated under the synergistic action of ultrasound, and the cycle continues. At the same time, the sludge and water treated by the sludge scraper on the oxidation tank are separated by a basket filter. The sludge is disposed of in a conventional manner, the water is discharged after meeting the standards, and the purified waste gas is discharged after meeting the standards.

[0076] (3) Clarification and buffering: Wastewater treated by the oxidation tank enters the buffer tank;

[0077] (4) Reuse pretreatment: The water in the buffer tank continues to enter the multi-media filter to treat suspended solids. The backwash water of the multi-media filter enters the homogenization tank. The water after multi-media treatment enters the ultrafiltration unit to further remove particulate matter in the multi-media effluent. The backwash water of the ultrafiltration is returned to the buffer tank.

[0078] (5) Reuse treatment: After the water is treated by the ultrafiltration unit, a reducing agent is added to remove the residual oxidant before it enters the reverse osmosis unit. The product water is reused, and the concentrate continues to enter the first-stage UV generator for treatment.

[0079] Example 1

[0080] The wastewater from a certain rubber plant has a chlorobenzene concentration of 200–350 mg / L, a COD of 300–500 mg / L, a suspended solids concentration of 500–1000 mg / L, and a conductivity of 150–300 μS / cm. The operating parameters are as follows.

[0081] Homogenizing tank: The hydraulic retention time is preferably 10 hours.

[0082] Oxidation tank: The oxidant is hydrogen peroxide, with a dry basis dosage ratio of 5:1 to the influent COD. The hydraulic retention time is preferably 4 hours, the reaction temperature is 50℃, and the effluent flow rate is 10 times that of the booster pump. The gas-water ratio of the waste gas to wastewater in the gas-water mixing pump is preferably 1:20. The ultrasonic frequency is 20–80 kHz, and the installed power is 500 W / m². 3 ;

[0083] Basket filter, with a precision of 20μm, has an outlet water volume of 25% of the wastewater volume.

[0084] Primary UV reactor: UV light wavelength 200–400 nm, power 3000 W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 60 seconds.

[0085] Secondary UV reactor: UV wavelength 185nm, power 400W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 300 seconds.

[0086] Buffer tank: hydraulic retention time 1 hour, hydrogen peroxide concentration 50-100 mg / L.

[0087] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment: the multi-media filter unit has a water production rate of 97%, the ultrafiltration unit has a water production rate of 90%; the reducing agent dosage is 20mg / L, and the reverse osmosis unit has a water production rate of 75%.

[0088] Operating results: Chlorobenzene concentration at the outlet of the homogenizer exhaust gas was 100–150 mg / m³. 3 The concentration of chlorobenzene at the top of the oxidation tank is 1-2 mg / m³. 3The drainage from the basket filter has a COD of 21-29 mg / L and a chlorobenzene concentration of <0.1 mg / L.

[0089] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 20-25 mg / L, conductivity of 300-400 μS / cm, and suspended solids of 10-20 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0090] The conductivity of the reverse osmosis permeate is 30-35 μS / cm, the wastewater reuse rate of the entire process is 75%, the ultrafiltration is chemically cleaned once a quarter, and the reverse osmosis is chemically cleaned once every six months.

[0091] Example 2

[0092] The wastewater from a certain rubber stripping unit has a chlorobenzene concentration of 60–100 mg / L, a COD of 80–100 mg / L, a suspended solids concentration of 100–300 mg / L, and a conductivity of 79–137 μS / cm. The operating parameters are as follows.

[0093] Homogenizing tank: The hydraulic retention time is preferably 1 hour.

[0094] Oxidation tank: The oxidant is hydrogen peroxide, with a dry basis dosage ratio of 2:1 to the influent COD. The hydraulic retention time is preferably 2 hours, the reaction temperature is 45℃, and the effluent flow rate is 5 times the booster pump flow rate. The gas-water ratio of waste gas to wastewater in the gas-water mixing pump is preferably 1:50. The ultrasonic frequency is 20–60 kHz, and the installed power is 200 W / m. 3 ;

[0095] Basket filter, with a precision of 10μm, has an outlet water volume of 15% of the wastewater volume.

[0096] First-stage UV reactor: UV light wavelength 200–400 nm, power 500 W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 120 seconds.

[0097] Secondary UV reactor: UV light wavelength 185nm, power 700W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 150 seconds.

[0098] Buffer tank: hydraulic retention time 2h, hydrogen peroxide concentration 20-50mg / L.

[0099] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment; multi-media filter unit water production rate 95%, ultrafiltration unit water production rate 95%; reducing agent dosage 10mg / L, reverse osmosis unit water production rate 75%.

[0100] Operating results: Chlorobenzene concentration at the outlet of the homogenizer exhaust gas was 30–50 mg / m³. 3The concentration of chlorobenzene at the top of the oxidation tank is 1-2 mg / m³. 3 The COD of the drain water from the basket filter is 16-22 mg / L and the chlorobenzene concentration is <0.1 mg / L.

[0101] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 15-21 mg / L, conductivity of 100-150 μS / cm, and suspended solids of 2-8 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0102] The reverse osmosis permeate has a conductivity of 20-30 μS / cm, the wastewater reuse rate of the entire process is 85%, and the ultrafiltration and reverse osmosis systems are chemically cleaned every six months.

[0103] Example 3

[0104] The mixed wastewater from a chemical and rubber plant has a chlorobenzene concentration of 100–200 mg / L, a COD of 500–650 mg / L, a suspended solids concentration of 100–300 mg / L, and a conductivity of 200–500 μS / cm. The operating parameters are as follows.

[0105] Homogenizing tank: The hydraulic retention time is preferably 4 hours.

[0106] Oxidation tank: The oxidant is hydrogen peroxide, with a dry basis dosage ratio of 8:1 to the influent COD. The hydraulic retention time is preferably 1 hour, the reaction temperature is 48℃, and the effluent flow rate is 15 times that of the booster pump. The gas-water ratio of the waste gas to wastewater in the gas-water mixing pump is preferably 1:20. The ultrasonic frequency is 40–80 kHz, and the installed power is 100 W / m². 3 ;

[0107] Basket filter, with a precision of 100μm, has an outlet water volume of 20% of the wastewater volume.

[0108] First-stage UV reactor: UV light wavelength 200–400 nm, power 500 W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 30 seconds.

[0109] Secondary UV reactor: UV light wavelength 185nm, power 100W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 600 seconds.

[0110] Buffer tank: hydraulic retention time 2h, hydrogen peroxide concentration 10-20mg / L.

[0111] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment, multi-media filter unit water production rate 95%, ultrafiltration unit water production rate 90%; reducing agent dosage 5mg / L, reverse osmosis unit water production rate 80%.

[0112] Operating results: Chlorobenzene concentration at the outlet of the homogenizer exhaust gas was 30–50 mg / m³.3 The concentration of chlorobenzene at the top of the oxidation tank is 1-2 mg / m³. 3 The COD of the drain water from the basket filter is 20-29 mg / L and the chlorobenzene concentration is <0.1 mg / L.

[0113] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 20-25 mg / L, conductivity of 200-500 μS / cm, and suspended solids of 1-6 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0114] The conductivity of the reverse osmosis permeate is 20–50 μS / cm, and the wastewater reuse rate is 80% throughout the entire process. The ultrafiltration and reverse osmosis systems undergo chemical cleaning every six months.

[0115] Comparative Example 1

[0116] The wastewater from a certain rubber plant has a chlorobenzene concentration of 200–350 mg / L, a COD of 300–500 mg / L, a suspended solids concentration of 500–1000 mg / L, and a conductivity of 150–300 μS / cm.

[0117] This invention employs some of the processes and parameters of the present invention, but differs from the present invention in that a dissolved air flotation system is installed after the oxidation tank, and polyaluminum flocculant is added to assist the flotation. Ultrasonic waves are not installed inside the oxidation tank, but a slag scraper is still installed. The operating parameters are as follows.

[0118] Homogenizing tank: Hydraulic retention time is preferably 10 hours;

[0119] Oxidation tank: The oxidant is hydrogen peroxide, the ratio of dry basis dosage to influent COD is 5:1, the hydraulic retention time is preferably 4h, the reaction temperature is 50℃, the effluent flow rate is 10 times the flow rate of the booster pump, and the gas-water ratio of waste gas to wastewater in the gas-water mixing pump is preferably 1:20.

[0120] Basket filter, with a precision of 20μm, has an outlet water volume of 25% of the wastewater volume;

[0121] Primary UV reactor: UV light wavelength 200–400 nm, power 3000 W / m 3 The wastewater area in the reaction tube has a hydraulic retention time of 60 seconds;

[0122] Secondary UV reactor: UV wavelength 185nm, power 400W / m 3 The hydraulic retention time in the wastewater area of ​​the reaction tube is 300 seconds.

[0123] The hydraulic retention time for dissolved air flotation is 0.5 h, and the flocculant dosage is 5 mg / L.

[0124] Buffer tank: hydraulic retention time 1 hour, hydrogen peroxide concentration 200-300 mg / L.

[0125] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment: the multi-media filter unit has a water production rate of 97%, the ultrafiltration unit has a water production rate of 90%, the reducing agent dosage is 100mg / L, and the reverse osmosis unit has a water production rate of 75%.

[0126] Operating results: Chlorobenzene concentration at the outlet of the homogenizer exhaust gas was 100–150 mg / m³. 3 The concentration of chlorobenzene at the top of the oxidation tank is 5-10 mg / m³. 3 The drainage from the basket filter has a COD of 40-60 mg / L and a chlorobenzene concentration of 1-5 mg / L.

[0127] The effluent from the buffer tank has a COD of 40-60 mg / L, a conductivity of 300-400 μS / cm, and a suspended solids concentration of 30-50 mg / L. The removal rates of chlorobenzene waste gas, chlorobenzene in water, and suspended solids have decreased, and the amount of wastewater discharged exceeds the local discharge standard by 40 mg / L.

[0128] The reverse osmosis permeate has a conductivity of 50-100 μS / cm, the wastewater reuse rate of the entire process is 75%, the ultrafiltration system is cleaned every half month, and the reverse osmosis system is cleaned once a month.

[0129] Compared with Example 1, without the ultrasonic action of the present invention, even with the subsequent addition of dissolved air flotation, the suspended solids in the buffer tank still increased, resulting in a decrease in the operating efficiency of the recycling device. At the same time, the large amount of hydrogen peroxide remaining in the buffer tank led to an increase in the subsequent addition of reducing agent. The hydrogen peroxide was not effectively utilized, resulting in the need for further treatment of the wastewater organic matter before discharge.

[0130] Of course, the above description is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the embodiments of the present invention. The present invention is also not limited to the above examples, and all equivalent changes and improvements made by those skilled in the art within the scope of the present invention should fall within the patent coverage of the present invention.

Claims

1. A method for recycling chlorinated benzene-containing wastewater from solution polymerization of rubber, characterized in that: Includes the following steps: (1) Homogenization: The chlorinated benzene wastewater from the solution-polymerized rubber is introduced into a homogenizing tank and air is introduced; (2) Oxidative flotation: The treated wastewater, oxidized wastewater, chlorobenzene waste gas, and reused concentrated water are fed together into a two-stage UV generator under the action of an oxidant. The first-stage UV generator uses UV lamps that can generate ultraviolet light with a wavelength of 200-400nm and a power of 300-3000W / m. 3 The secondary UV generator uses ultraviolet lamps that emit ultraviolet light with a wavelength less than 200nm, and has a power of 100–700W / m. 3 The wastewater undergoes oxidation treatment, and the treated wastewater enters the oxidation tank. Under the synergistic effect of ultrasound, the wastewater and exhaust gas are further treated, and this cycle continues. At the same time, the slag and water treated by the slag scraper on the oxidation tank are separated by the basket filter. The scum is disposed of in a conventional manner, the water is discharged after meeting the standards, and the purified exhaust gas is discharged after meeting the standards. When the homogenized wastewater and the oxidized wastewater are fed into the UV generator together, the flow rate of the oxidized wastewater is 5 to 15 times the flow rate of the homogenizing tank lift pump; the gas-water ratio of the total wastewater to the exhaust gas is 1:20 to 1:100; the filtration accuracy of the basket filter in step (2) is 10 to 100 μm. (3) Clarification and buffering: Wastewater treated by the oxidation tank enters the buffer tank; (4) Reuse pretreatment: The water in the buffer tank continues to enter the multi-media filter to treat suspended solids. The filtration rate of the multi-media filter is 5-10 m / h and the water production rate is over 95%. The backwash water of the multi-media filter enters the homogenization tank. The water after multi-media treatment enters the ultrafiltration unit to further remove particulate matter in the multi-media effluent. The water production rate of the ultrafiltration unit is 85%-95%. The backwash water of the ultrafiltration unit is returned to the buffer tank. (5) Reuse treatment: After the water is treated by the ultrafiltration unit, a reducing agent is added to remove the residual oxidant before entering the reverse osmosis unit. The permeate is reused, and the concentrate continues to enter the first-stage UV generator for treatment.

2. The method for recycling chlorinated benzene wastewater from solution polymerization of rubber according to claim 1, characterized in that: The hydraulic retention time in the wastewater homogenization process in step (1) is 1 to 10 hours; the hydraulic retention time in the oxidation tank in step (2) is 1 to 4 hours based on the influent; and the oxidation reaction temperature is 45 to 50°C.

3. The method for recycling chlorinated benzene wastewater from solution polymerization of rubber according to claim 1, characterized in that: In step (2), the oxidant is hydrogen peroxide; the ratio of the dry basis dosage of the oxidant to the COD of the influent is 2:1 to 8:

1.

4. The method for recycling chlorinated benzene wastewater from solution polymerization of rubber according to claim 1, characterized in that: In step (2), the ultrasonic frequency is 20–80 kHz, frequency sweep operation is used, and the installed power is 100–500 W / m. 3 .

5. The method for recycling chlorinated benzene wastewater from solution polymerization of rubber according to claim 1, characterized in that: When the wastewater treated by the oxidation tank in step (3) enters the buffer tank, the residual oxidant is 10-100 mg / L.

6. The method for recycling chlorinated benzene wastewater from solution polymerization of rubber according to claim 1, characterized in that: The reducing agent in step (5) is sodium bisulfite, with a concentration of 5–20 mg / L.

7. A device for recycling chlorinated benzene wastewater from solution polymerization of rubber according to any one of claims 1-6, characterized in that: The homogenizing tank (1) is connected to the oxidation tank (2), and the oxidation tank (2) is connected to the buffer tank (5) through the oxidation tank outlet three (27); the buffer tank (5) is connected to the multi-media filter (6), and the multi-media filter (6) is connected to the ultrafiltration unit (7); the ultrafiltration unit (7) is connected to the reverse osmosis unit (8); the homogenizing tank (1) is equipped with a wastewater inlet pipe (14), a waste gas outlet pipe (15), an air inlet (16), and a homogenizing tank outlet (24); The homogenizing tank (1) is connected to the homogenizing tank lift pump (22) through the homogenizing tank outlet (24). The homogenizing tank lift pump (22) is connected to the circulation pump (23). The circulation pump (23) is connected to the first-stage UV generator (11). The first-stage UV generator (11) is connected to the second-stage UV generator (30). The second-stage UV generator (30) is connected to the oxidation tank (2) through the second oxidation tank outlet (26). An oxidant inlet pipe (13) and a waste gas circulation pipe (12) are provided between the homogenizing tank lift pump (22) and the circulation pump (23). The waste gas circulation pipe (12) is connected to the waste gas outlet pipeline (15). The oxidation tank (2) is equipped with a slag scraper (3) and an ultrasonic generator (21). The oxidation tank (2) is equipped with an oxidation tank outlet 1 (25), an oxidation tank outlet 2 (26), an oxidation tank outlet 3 (27), and a tail gas outlet (17). The oxidation tank outlet 1 (25) is connected to the outlet of the homogenizing tank lifting pump (22). The oxidation tank (2) is connected to the basket filter (28), and the basket filter (28) is connected to the scum device (4); A backwash water pipe (18) is provided between the homogenizing tank (1) and the multi-media filter (6); a backwash water pipe (19) is provided between the ultrafiltration unit (7) and the buffer tank (5); a reducing agent inlet pipe (20) is provided on the pipeline between the ultrafiltration unit (7) and the reverse osmosis unit (8).

8. The solution polymerization rubber chlorinated benzene wastewater recycling device according to claim 7, characterized in that: The reverse osmosis unit (8) is connected to both the recycled water recovery device (9) and the wastewater treatment plant concentrate recovery pipe (10); the wastewater treatment plant concentrate recovery pipe (10) is connected to the circulating pump (23).

9. The solution polymerization rubber chlorinated benzene wastewater recycling device according to claim 7, characterized in that: An external drain pipe (29) is provided on the basket filter (28).

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