Method and device for recycling chlorobenzene rubber wastewater

Abstract

This invention belongs to the field of wastewater treatment technology, specifically relating to a method and apparatus for reusing chlorinated benzene rubber wastewater. The method includes the following steps: homogenization: introducing the chlorinated benzene rubber wastewater into a homogenization tank and introducing air to discharge chlorine-containing waste gas; oxidative flotation: subjecting the treated wastewater, oxidized wastewater, and chlorinated benzene-containing waste gas to oxidation treatment, then re-entering the oxidation tank for further treatment under ultrasonic synergistic action, and repeating this cycle to remove organic matter and suspended solids; clarification and buffering: the oxidized wastewater enters a buffer tank; pretreatment for reuse: the water after multi-media treatment enters an ultrafiltration unit to further remove particulate matter from the multi-media effluent; reuse treatment: the remaining wastewater enters a reverse osmosis unit for reuse, and the concentrated wastewater is sent to a wastewater treatment plant. This invention provides a method for reusing chlorinated benzene rubber wastewater that is environmentally friendly, produces high-quality wastewater, and has a high production rate; this invention also provides a reuse apparatus.

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 rubber wastewater. Background Technology

[0002] Chlorobenzene is a colorless, transparent, volatile liquid with an almond-like odor. It is commonly used as a dye, pharmaceutical, pesticide, intermediate in organic synthesis, and solvent. Therefore, in rubber production, chlorobenzene is often used as an additive or solvent in solution polymerization, resulting in chlorobenzene-containing rubber wastewater. While chlorobenzene has low solubility in water under normal conditions, the concentration of chlorobenzene in the wastewater entering the production process can reach over 200 mg / L. This chlorobenzene-containing wastewater poses a serious threat to the environment, polluting water bodies, soil, and the atmosphere. It is toxic to aquatic organisms and may have long-term adverse effects on the aquatic environment. Therefore, chlorobenzene-containing wastewater must undergo environmentally friendly treatment, taking into account the environmental impact of the treatment process on chlorobenzene volatilization.

[0003] In rubber production, most chlorobenzene is recovered and reused through physical methods, while the remaining chlorobenzene is transferred to wastewater. Direct discharge of this wastewater into a sewage treatment plant would inevitably impact the activated sludge, leading to substandard wastewater discharge. Although activated sludge capable of degrading chlorobenzene can be cultivated over time, fluctuations in the influent chlorobenzene concentration will again impact the sludge in the sewage treatment plant, which is detrimental to its stable operation. Therefore, chlorobenzene-containing wastewater must be treated separately or have its microbial toxicity removed before being discharged into the sewage treatment plant.

[0004] When chlorobenzene in rubber wastewater is difficult to treat directly using physical and biological methods, advanced oxidation technologies (AEOs) need to be considered. AEOs are currently widely used to treat wastewater that is difficult to biodegrade, such as Fenton oxidation, photocatalytic oxidation, and high-temperature wet catalytic oxidation. These technologies can pretreat or deeply treat chlorobenzene-containing wastewater, but the treatment costs are usually high. If the chlorobenzene-containing wastewater after AEOs can be reused, it will improve water resource utilization and the economic efficiency of treatment costs.

[0005] Rubber wastewater often contains rubber particles, which tend to clump together when filtered using conventional methods, necessitating flotation treatment. However, conventional flotation is insufficient to remove these particles effectively enough to meet the pretreatment requirements for wastewater reuse, thus limiting the reuse of this type of wastewater. Therefore, rubber wastewater reuse typically involves first using conventional flotation to remove suspended rubber particles, followed by a long-term biological treatment process, before considering reuse.

[0006] 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 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; and 6) reverse osmosis membrane section. The final product is 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 filtration is not suitable for wastewater containing rubber particles, which 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, making it unsuitable for reuse in treating rubber wastewater containing rubber particles.

[0007] 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. This invention can effectively remove the adverse effects of pollutants in chloroprene rubber industrial wastewater on ultrafiltration and reverse osmosis membranes at a relatively low cost. It enables the chloroprene rubber industrial wastewater to meet the reverse osmosis feed water quality requirements and undergoes 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 was found that low concentrations of flocculants and coagulants have poor flocculation effects. Even with high concentrations of flocculants and coagulants, most of the rubber particles cannot be removed with coagulation and sedimentation, leading to severe clogging of subsequent multi-media and ultrafiltration processes. The added chemicals themselves also have a clogging effect on subsequent ultrafiltration and reverse osmosis. At the same time, this invention lacks organic matter removal facilities, and organic matter in the water will also cause fouling and clogging of subsequent reverse osmosis processes, which is not conducive to stable operation.

[0008] In summary, the following technical problems exist in the current process of reusing chlorinated benzene rubber wastewater:

[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, and increases the salt content of the wastewater, making reuse more difficult.

[0012] 4. Rubber chlorobenzene wastewater contains many additives and rubber particles, making it difficult to reuse. Traditional air flotation methods are incomplete in removing rubber particles and cause chlorobenzene to leak out, increasing the burden on subsequent exhaust gas treatment.

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

[0014] The technical problem to be solved by the present invention is to provide a method for recycling chlorinated benzene rubber wastewater, which is environmentally friendly, with no harmful gases escaping, and produces high-quality water with a high water production rate; the present invention also provides a recycling device.

[0015] The method for reusing chlorinated benzene rubber wastewater according to the present invention includes the following steps:

[0016] (1) Homogenization: The chlorinated benzene rubber wastewater 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.

[0017] (2) Oxidative flotation: The treated wastewater, oxidized wastewater and chlorinated benzene-containing waste gas are fed together into a UV generator under the action of an oxidant for oxidation treatment. The treated wastewater then enters an oxidation tank, where wastewater and waste gas are further treated under the synergistic effect of ultrasound. This cycle is repeated to remove organic matter and suspended solids. At the same time, the scum scraped by the scum scraper on the oxidation tank enters a scum flotation device, and the purified waste gas is discharged in compliance with standards.

[0018] (3) Clarification and buffering: Wastewater treated by the oxidation tank enters the buffer tank;

[0019] (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.

[0020] (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 concentrated water is sent to the sewage treatment plant for treatment.

[0021] 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; in step (2), the wastewater enters the oxidation tank, and the oxidation tank material is preferably, but not limited to, polytetrafluoroethylene, polyethylene, and anti-corrosion lining. The hydraulic residence time is 1 to 4 hours based on the influent. The oxidation reaction temperature is 50 to 55°C, and the control method is preferably, but not limited to, ultraviolet power adjustment.

[0022] In step (2), the oxidant is hydrogen peroxide or ozone; the ratio of the amount of oxidant added to the COD of the influent is 1:1 to 10:1.

[0023] An ultrasonic generator, including an ultrasonic power supply and a transducer, is installed at the bottom of the oxidation tank described in step (2). The ultrasonic frequency is preferably, but not limited to, 20–80 kHz, and it operates by frequency sweep. The installed power is 100–500 W / m. 3 .

[0024] When the wastewater treated by the oxidation tank in step (3) enters the buffer tank, the residual oxidant is 3-50 mg / L.

[0025] In step (2), when the homogenized wastewater and the oxidized wastewater are introduced into the UV generator together, the flow rate of the oxidized wastewater is 3 to 10 times the flow rate of the homogenizing tank lift pump; the circulating pump in step (2) is preferably a gas-water mixing pump, the flow rate of the oxidizing tank outlet and the flow rate of the lift pump are designed, the gas-water ratio of waste gas and wastewater is preferably 1:20 to 1:100, and the air intake is controlled by the homogenizing tank fixed one-way air port.

[0026] The reducing agent added to the reverse osmosis unit in step (5) is preferably, but not limited to, sodium bisulfite, with a concentration of 3 to 8 mg / L.

[0027] The chlorinated benzene rubber wastewater recycling device consists of: a homogenizing tank connected to an oxidation tank; the oxidation tank connected to a buffer tank via its outlet three; a buffer tank connected to a multi-media filter; a multi-media filter connected to an ultrafiltration unit; an ultrafiltration unit connected to a reverse osmosis unit; and a wastewater inlet pipe, a waste gas outlet pipe, an air inlet, and a homogenizing tank outlet.

[0028] 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 UV generator. The 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.

[0029] 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.

[0030] 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.

[0031] The reverse osmosis unit is connected to both the recycled water recovery system and the wastewater treatment plant;

[0032] The oxidation tank is equipped with a scum-scavenging device and a scum scraper, designed according to the conventional air flotation scum scraper.

[0033] The UV generator consists of a power supply, a UV lamp, and a reaction tube. The UV lamp is capable of emitting UV light with a wavelength of 200–400 nm, preferably a medium-voltage UV lamp, and the preferred installation power is 500–3000 W / m. 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 and the wastewater medium. The wastewater and waste gas reaction area is preferably made of, but not limited to, quartz, polytetrafluoroethylene, or polyethylene. The preferred effective volume is calculated based on the influent hydraulic retention time of 30–120 s.

[0034] The hydraulic retention time of the buffer tank, calculated based on the influent, is preferably 1 to 2 hours.

[0035] 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, with a preferred filtration rate of 5 to 10 m / h.

[0036] The multi-media filter has a water production rate of over 95%. The backwash water inlet uses the multi-media filter outlet water, and the backwash water outlet water is returned to the homogenization tank.

[0037] The ultrafiltration unit is a conventional wastewater reuse ultrafiltration unit, designed according to conventional methods.

[0038] The ultrafiltration unit has a water production rate of 85% to 95%, and the backwash influent is ultrafiltration effluent, which is returned to the buffer tank.

[0039] 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%.

[0040] Specifically, the method for reusing chlorinated benzene rubber wastewater includes the following steps:

[0041] (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 into the environment after the wastewater enters the homogenizing tank.

[0042] (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 the UV generator for oxidation treatment. At a certain temperature in the UV generator, the organic matter in the wastewater 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. Meanwhile, the 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 effluent from the UV generator enters the oxidation tank, and under the synergistic effect of ultrasound in the oxidation tank, the oxidant and strong oxidizing radicals in the effluent from the UV generator continue to efficiently degrade the organic matter in the wastewater. At the same time, the suspended solids are removed by efficient flotation under the action of small bubbles, ultrasonic cavitation, and the pressure release of the purified waste gas. Control the amount of oxidant added and circulate it through a UV generator to ensure the treatment effect of chlorobenzene and other organic matter.

[0043] 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 scum scraper is installed at the top of the oxidation tank, and the scum is disposed of in a subsequent conventional scum treatment process. The purified exhaust gas is discharged from the top of the oxidation tank after meeting emission standards. The purpose of this step is to purify the waste gas, remove organic matter such as chlorobenzene from the wastewater, and remove suspended solids without increasing the salt content of the wastewater, thus creating conditions for reuse.

[0044] (3) Clarification and buffering: The effluent from the oxidation tank enters the buffer tank, which serves as a buffer for subsequent reuse.

[0045] (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.

[0046] (5) Reuse treatment: After adding a reducing agent to remove residual oxidant, the ultrafiltration effluent enters the conventional reverse osmosis unit. The permeate is reused, and the concentrate is sent to the wastewater treatment plant.

[0047] The implementation process of the chlorinated benzene rubber wastewater reuse device of the present invention is as follows:

[0048] 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 and mixed with chlorobenzene exhaust gas from the top of the homogenizing tank before entering a UV generator for oxidation treatment. In the 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 air flotation. The effluent from the UV generator enters the oxidation tank, where, under the synergistic effect of ultrasound, the oxidant and strong free radicals in the effluent continue to efficiently degrade the organic matter in the wastewater. Meanwhile, suspended solids are removed through efficient air flotation due to the adhesion of microbubbles, ultrasonic cavitation, and the release of purified exhaust gas pressure. The influent and effluent from the UV generator circulate in the lower part of the oxidation tank, continuously degrading organic matter. The purified exhaust gas is discharged from the top; the scum generated by air flotation in the oxidation tank is collected and discharged by a scraper at the top of the oxidation tank; and the effluent from the oxidation tank is discharged from the upper middle part into a buffer tank. The remaining 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 water is reused, and the concentrated chlorine-benzene water meets the standards and can be directly sent to the wastewater treatment plant for further treatment before discharge. The backwash water from the multi-media unit is returned to the homogenizing tank, and the backwash water from the ultrafiltration unit is returned to the buffer tank to improve the wastewater reuse rate.

[0049] The UV generator used in this invention emits ultraviolet light that causes pollutants to absorb the ultraviolet light and enter a form that is easily degradable. Simultaneously, it catalyzes the oxidant to produce hydroxyl radicals and nascent oxygen. Microbubbles generated within the UV generator adhere to suspended solids, destabilizing them. The purified waste gas and the gases produced in the reaction, under ultrasonic treatment, create a synergistic and highly efficient flotation effect, effectively removing suspended particles and ensuring a high removal rate of colloids and other suspended solids from wastewater. This further guarantees the operational efficiency of the reuse device.

[0050] This invention utilizes the synergistic oxidation effect of ultrasound, oxidants, virgin oxygen, and hydroxyl radicals to efficiently remove organic matter, significantly reducing the organic matter content in the influent of the reuse device and ensuring the operating efficiency of the reuse device.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) This invention introduces waste gas into the wastewater treatment pipeline and treats wastewater and waste gas using the same device, saving waste gas investment and land occupation, and ensuring that no harmful gases escape during the reuse process; the invention process is compact and occupies a small area.

[0053] (2) This invention uses high-intensity ultraviolet light, synergistic oxidant and ultrasound, which has high advanced oxidation efficiency, thoroughly removes chlorobenzene characteristic pollutants, and degrades most of the organic matter.

[0054] (3) The microbubbles generated in the UV generator of the present invention make the suspended matter in a state that is easily removed by air flotation. The purified waste gas and the gas produced by the reaction produce a synergistic and efficient air flotation effect under the use of ultrasound, effectively removing suspended particles, ensuring the removal rate of suspended particles and other suspended matter in wastewater, and further ensuring the operating efficiency of the reuse device.

[0055] (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.

[0056] (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.

[0057] (6) The oxidation cost in the treatment of chlorinated benzene wastewater is high, and the treated wastewater is reused instead of being discharged. The method of the present invention improves the utilization rate of water resources and improves the economic efficiency of wastewater operation costs.

[0058] (7) The concentrated water treated by the method of the present invention is not toxic to organisms and can be sent to a sewage treatment plant for biological treatment before being discharged; the scum does not contain chlorobenzene characteristic pollutants, which reduces the hazardous waste level of subsequent disposal. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the chlorinated benzene rubber wastewater recycling device of the present invention;

[0060] 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 plant; 11. 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 booster pump; 23. Circulation pump; 24. Homogenizing tank outlet; 25. Oxidizing tank outlet one; 26. Oxidizing tank outlet two; 27. Oxidizing tank outlet three. Detailed Implementation

[0061] The embodiments all use the chlorinated benzene rubber wastewater recycling device of the present invention, which further illustrates the beneficial effects of the present invention.

[0062] like Figure 1As shown, the chlorinated benzene rubber 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.

[0063] Homogenizing tank 1 is connected to homogenizing tank lift pump 22 through homogenizing tank outlet 24. Homogenizing tank lift pump 22 is connected to circulation pump 23. Circulation pump 23 is connected to UV generator 11. UV generator 11 is connected to oxidation tank 2 through 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.

[0064] 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.

[0065] 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.

[0066] The reverse osmosis unit 8 is connected to both the recycled water recovery device 9 and the wastewater treatment plant 10.

[0067] Oxidation tank 2 is connected to scum device 4.

[0068] All examples employ the chlorinated benzene rubber wastewater reuse method of the present invention, which includes the following steps:

[0069] (1) Homogenization: The chlorinated benzene rubber wastewater 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.

[0070] (2) Oxidative flotation: The treated wastewater, oxidized wastewater and chlorinated benzene-containing waste gas are fed together into a UV generator under the action of an oxidant for oxidation treatment. The treated wastewater then enters an oxidation tank, where wastewater and waste gas are further treated under the synergistic effect of ultrasound. This cycle is repeated to remove organic matter and suspended solids. At the same time, the scum scraped by the scum scraper on the oxidation tank enters a scum flotation device, and the purified waste gas is discharged in compliance with standards.

[0071] (3) Clarification and buffering: Wastewater treated by the oxidation tank enters the buffer tank;

[0072] (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.

[0073] (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 concentrated water is sent to the sewage treatment plant for treatment.

[0074] Example 1

[0075] The wastewater from a certain special rubber plant has a chlorobenzene concentration of 200–350 mg / L, COD of 300–500 mg / L, suspended solids of 500–1000 mg / L, and conductivity of 150–300 μS / cm. The operating parameters are as follows:

[0076] Homogenizing tank: The hydraulic retention time is preferably 10 hours.

[0077] Oxidation tank: The oxidant is hydrogen peroxide solution, with a dry basis dosage ratio of 6:1 to the influent COD. The hydraulic retention time is preferably 4 hours, the reaction temperature is 50–52℃, 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 1:50. The ultrasonic frequency is 20–80 kHz, and the installed power is 500 W / m². 3 The scum outlet water volume is 2% of the influent.

[0078] UV reactor: UV light wavelength 200-400nm, power 3000W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 30 seconds.

[0079] Buffer tank: hydraulic retention time 1 hour, hydrogen peroxide concentration 20-50 mg / L.

[0080] 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 85%; the reducing agent dosage is 5mg / L, and the reverse osmosis unit has a water production rate of 80%.

[0081] 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. 3 ;

[0082] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 25-35 mg / L, conductivity of 150-300 μS / cm, and suspended solids of 10-20 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0083] The conductivity of the reverse osmosis permeate is 10–15 μS / cm, the conductivity of the concentrate is 700–1500 μS / cm, the chlorobenzene concentration is <0.1 mg / L, and the COD is 150–180 mg / L.

[0084] The wastewater reuse rate is 78.4% throughout the entire process. The ultrafiltration system is chemically cleaned once a quarter, and the reverse osmosis system is chemically cleaned once every six months. The operation is stable.

[0085] Example 2

[0086] The wastewater from a 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:

[0087] Homogenizing tank: The hydraulic retention time is preferably 1 hour.

[0088] Oxidation tank: The oxidant is hydrogen peroxide solution, with a dry basis dosage ratio of 1:1 to the influent COD. The hydraulic retention time is preferably 2 hours, the reaction temperature is 53–55℃, and the effluent flow rate is 3 times the booster pump flow rate. The gas-water ratio of 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 200 W / m². 3 The scum outlet water volume is 2% of the influent.

[0089] The scum outlet water volume is 2% of the influent.

[0090] 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.

[0091] Buffer tank: hydraulic retention time 2h, hydrogen peroxide concentration 3-20mg / L.

[0092] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment, with a water production rate of 95% for both the multi-media filter and ultrafiltration units; reducing agent dosage of 3 mg / L, and a water production rate of 85% for the reverse osmosis unit.

[0093] 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 ;

[0094] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 10-15 mg / L, conductivity of 80-140 μS / cm, and suspended solids of 5-10 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0095] The conductivity of the reverse osmosis permeate is 15–30 μS / cm, the conductivity of the concentrate is 550–1100 μS / cm, the chlorobenzene concentration is <0.1 mg / L, and the COD is 70–110 mg / L.

[0096] The wastewater reuse rate is 83.3% throughout the entire process. The ultrafiltration and reverse osmosis systems are chemically cleaned every six months, and the operation is stable.

[0097] Example 3

[0098] 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.

[0099] Homogenizing tank: The hydraulic retention time is preferably 4 hours.

[0100] Oxidation tank: The oxidant is hydrogen peroxide solution, with a dry basis dosage ratio of 10:1 to the influent COD. The hydraulic retention time is preferably 1 hour, the reaction temperature is 50–53℃, and the effluent flow rate is 6 times that of the booster pump. The gas-water ratio of the waste gas to wastewater in the gas-water mixing pump is preferably 1:100. The ultrasonic frequency is 20–60 kHz, and the installed power is 100 W / m². 3 The scum outlet water volume is 2% of the influent.

[0101] The scum outlet water volume is 3% of the influent.

[0102] UV reactor: UV light wavelength 200-400nm, power 2000W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 60 seconds.

[0103] Buffer tank: hydraulic retention time 2h, hydrogen peroxide concentration 30-50mg / L.

[0104] Multi-media filter + ultrafiltration + reverse osmosis desalination and reuse treatment; multi-media filter unit has a water production rate of 95%, ultrafiltration unit has a water production rate of 90%; reducing agent dosage is 8mg / L, reverse osmosis unit has a water production rate of 75%.

[0105] Operating results: Chlorobenzene concentration at the outlet of the homogenizer exhaust gas was 50–100 mg / m³. 3 The concentration of chlorobenzene at the top of the oxidation tank is 1-2 mg / m³. 3 ;

[0106] The effluent from the buffer tank has a chlorobenzene concentration of <0.1 mg / L, COD of 22-35 mg / L, conductivity of 200-500 μS / cm, and suspended solids of 5-10 mg / L. Chlorobenzene waste gas, chlorobenzene in water, and suspended solids are all effectively removed.

[0107] The conductivity of the reverse osmosis permeate is 20–45 μS / cm, the conductivity of the concentrate is 800–2000 μS / cm, the chlorobenzene concentration is <0.1 mg / L, and the COD is 91–150 mg / L.

[0108] The wastewater reuse rate is 72.8% throughout the entire process. The ultrafiltration and reverse osmosis systems are chemically cleaned every six months, and the operation is stable.

[0109] Comparative Example 1

[0110] The wastewater from a certain special 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.

[0111] The process and parameters of this invention are adopted, but the difference from this invention is that dissolved air flotation is set after the oxidation tank, and polyaluminum flocculant is added to assist the flotation. Ultrasonic waves are not set in the oxidation tank, but a slag scraper is still set. The operating parameters are as follows.

[0112] Homogenizing tank: The hydraulic retention time is preferably 10 hours.

[0113] Oxidation tank: The oxidant is hydrogen peroxide solution, with a dry basis dosage ratio of 6:1 to the influent COD. The hydraulic retention time is preferably 4 hours, the reaction temperature is 50–52℃, 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 1:50. The ultrasonic frequency is 20–80 kHz, and the installed power is 500 W / m². 3 The scum outlet water volume is 2% of the influent.

[0114] UV reactor: UV light wavelength 200-400nm, power 3000W / m 3 The sewage area in the reaction tube has a hydraulic retention time of 30 seconds.

[0115] The hydraulic retention time for dissolved air flotation is 0.5 h, and the flocculant dosage is 5 mg / L.

[0116] Buffer tank: hydraulic retention time 1 hour, hydrogen peroxide concentration 100-200 mg / L.

[0117] 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 85%; the reducing agent dosage is 80 mg / L, and the reverse osmosis unit has a water production rate of 80%.

[0118] 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 ;

[0119] The effluent from the buffer tank has a chlorobenzene concentration of <3 mg / L, COD of 40–75 mg / L, conductivity of 150–300 μS / cm, and suspended solids of 50–100 mg / L. The removal rates of chlorobenzene in waste gas, chlorobenzene in water, and suspended solids decrease.

[0120] The conductivity of the reverse osmosis permeate is 30–50 μS / cm, the conductivity of the concentrate is 700–1500 μS / cm, the chlorobenzene concentration is <10 mg / L, and the COD is 20–380 mg / L.

[0121] Ultrafiltration requires chemical cleaning every 10 days, while reverse osmosis requires cleaning once a month; otherwise, ultrafiltration will struggle to maintain normal operation.

[0122] Compared with Example 1, without the ultrasonic action of the present invention in the oxidation tank, even with the subsequent addition of dissolved air flotation, the suspended solids and COD in the buffer tank were still high, resulting in a decrease in the operating efficiency of the recycling device. At the same time, there was a large amount of hydrogen peroxide remaining in the buffer tank, indicating that the oxidation efficiency of the oxidation tank decreased, which led to an increase in the subsequent addition of reducing agent and an increase in the difficulty of treating the organic matter in the wastewater.

[0123] 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 reusing chlorinated benzene rubber wastewater, characterized in that: Includes the following steps: (1) Homogenization: The chlorinated benzene rubber wastewater is introduced into a homogenizing tank and air is introduced; (2) Oxidative flotation: The treated wastewater, oxidized wastewater and chlorine-containing waste gas are fed into a UV generator under the action of an oxidant for oxidation treatment. The treated wastewater then enters an oxidation tank, where wastewater and waste gas are treated again under the synergistic effect of ultrasound, and the cycle continues. At the same time, the scum treated by the scraper on the oxidation tank enters a scum device, and the purified waste gas is discharged in compliance with standards. The oxidant is hydrogen peroxide or ozone; the ratio of the oxidant dosage to the influent COD is 1:1 to 10:

1. When the homogenized wastewater and the oxidized wastewater are fed into the UV generator together, the effluent flow rate of the oxidized wastewater is 3 to 10 times the flow rate of the homogenizing tank lift pump. (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 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. (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 concentrated water is sent to the sewage treatment plant for treatment. The chlorinated benzene rubber wastewater recycling device includes a homogenizing tank (1) connected to an oxidation tank (2). The oxidation tank (2) is connected to a buffer tank (5) through an oxidation tank outlet three (27). The buffer tank (5) is connected to a multi-media filter (6). The multi-media filter (6) is connected to an ultrafiltration unit (7). The ultrafiltration unit (7) is connected to a 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 UV generator (11), and the UV generator (11) is connected to the oxidation tank (2) through the 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), and 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). 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).

2. The method for reusing chlorinated benzene rubber wastewater 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 50 to 55°C.

3. The method for reusing chlorinated benzene rubber wastewater 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 .

4. The method for reusing chlorinated benzene rubber wastewater 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 3-50 mg / L.

5. The method for reusing chlorinated benzene rubber wastewater according to claim 1, characterized in that: The total wastewater to waste gas gas ratio in step (2) is 1:20 to 1:

100.

6. The method for reusing chlorinated benzene rubber wastewater according to claim 1, characterized in that: The reducing agent in step (5) is sodium bisulfite, with a concentration of 3-8 mg / L.

7. The method for reusing chlorinated benzene rubber wastewater according to claim 1, characterized in that: The reverse osmosis unit (8) is connected to both the recycled water recovery unit (9) and the wastewater treatment plant (10).

8. The method for reusing chlorinated benzene rubber wastewater according to claim 7, characterized in that: A scum device (4) is installed inside the oxidation tank (2).

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