Method and device for treating wastewater containing high-concentration chlorobenzene and acetone

Abstract

The invention belongs to the technical field of wastewater treatment, and particularly relates to a method and a device for treating wastewater containing high-concentration chlorobenzene and acetone. Wastewater firstly enters a homogenizing tank to be buffered and homogenized and then enters a first-stage oxidation pond from the bottom, an oxidizing agent and an ultraviolet reactor are added into the first-stage oxidation pond to carry out oxidation cycle treatment, and chlorobenzene is subjected to oxidation reaction in the first-stage oxidation pond to be quickly degraded into a non-volatile intermediate product. Acetone and water form azeotrope in the first-stage oxidation pond, the azeotrope is discharged into the condensation tank through a pipeline at the upper part of the first-stage oxidation pond, and acetone gas is condensed into liquid in the condensation tank; on the basis of an existing photocatalytic oxidation process, only an oxidizing agent is added into a primary oxidation pond, chlorobenzene is subjected to rapid photolysis into an intermediate product difficult to volatilize in the oxidizing agent, and meanwhile, an acetone and water azeotrope is formed in the primary oxidation pond by controlling the reaction temperature, so that chlorobenzene and acetone in wastewater are separated.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a method and a device for treating wastewater containing high-concentration chlorobenzene and acetone. Background Art

[0002] Chlorobenzene and acetone are organic solvents widely used in rubber industry production, which will produce wastewater containing high concentrations of chlorobenzene and acetone. It is one of the most difficult industrial wastewaters to treat and has the characteristics of high biological toxicity. It is difficult to treat it to meet the standards using conventional biological treatment processes, and oxidation pretreatment measures must be added.

[0003] Photocatalytic oxidation is an advanced oxidation technology that is effective in treating chlorobenzene and acetone. Under the action of ultraviolet light and catalyst, characteristic pollutants in sewage absorb photon energy to form high-energy excited molecules, and the oxidant hydrogen peroxide is decomposed into highly reactive hydroxyl radicals. The two undergo an oxidative decomposition reaction, thereby completely degrading organic pollutants in wastewater.

[0004] Compared with the insoluble nature of chlorobenzene, acetone is an organic matter that is easily soluble in water. In the existing photocatalytic oxidation process, due to the influence of different solubilities, the oxidation reaction time is long, the dosage of oxidants and catalysts is large, and the operating cost is high. If chlorobenzene and acetone in sewage can be separated and treated separately, the oxidation efficiency can be effectively improved. At the same time, acetone is a high-quality carbon source for biological denitrification treatment, and the separated acetone can be recycled.

[0005] Patent CN 105819588 A discloses a method for reducing pollutant emissions in the production of phenol acetone, comprising at least one of the following steps: (A) collecting phenol-containing wastewater generated by a phenol acetone production device, adjusting the pH to acidic, and extracting and recovering phenols in the wastewater using isopropylbenzene as an extractant; (B) reducing the acetone content of the wastewater in the bottom of the tower by optimizing the process of the acetone refining tower; (C) treating the wastewater in the bottom of the acetone refining tower with a selective permeable membrane to recover alkali; (D) after step (C) recovering alkali, the wastewater in the bottom of the acetone refining tower is neutralized and mixed with the condensate at the top of the isopropylbenzene oxidation tower for detoxification treatment; (E) performing oil separation treatment on the total drainage of the phenol acetone device to recover organic matter including hydrocarbons; (F) performing biological treatment, coagulation sedimentation treatment and enhanced degradation treatment on the wastewater after oil separation treatment. This method has the function of recovering acetone, but adds an acetone refining unit, increases the production process and energy consumption, and is not suitable for the case where the sewage also contains chlorobenzene, a volatile substance.

[0006] Patent CN 115536187 A discloses a method and device for treating chlorobenzene-containing wastewater. The wastewater first enters a homogenization tank for buffering, and then is mixed with the outlet water of the oxidation tank and the chlorobenzene waste gas at the top of the homogenization tank, and then enters a UV generator for oxidation cycle treatment; the water outlet from the top of the oxidation tank is adjusted for pH value and then enters a laminated filter, where the catalyst solid particles are intercepted, and the filter outlet water is adjusted for pH value again to a monitoring pool and then discharged to meet the standards; the backwash water of the laminated filter contains catalyst, and enters a catalyst tank for catalyst recovery, and the recovered catalyst is injected into the oxidation tank through a reagent pump; the tail gas is discharged from the top of the oxidation tank to meet the standards. This invention realizes the oxidation degradation of chlorobenzene in wastewater through an ultraviolet generator, but when this method is used to simultaneously treat acetone contained in wastewater, not only the amount of oxidant and catalyst added increases, but also the acetone is not recycled.

[0007] In summary, the following technical problems exist in the process of using existing photocatalytic oxidation technology to treat wastewater containing high concentrations of chlorobenzene and acetone:

[0008] 1. Chlorobenzene and acetone in sewage are not separated, and the dosage of oxidant and catalyst is large. Affected by different solubilities, the oxidation reaction time is long and the operating cost is high.

[0009] 2. Acetone is not effectively recycled. Summary of the invention

[0010] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for treating wastewater containing high concentrations of chlorobenzene and acetone. On the basis of the existing photocatalytic oxidation process, only an oxidant is added to the primary oxidation tank, and chlorobenzene is rapidly photolyzed into a non-volatile intermediate product. At the same time, by controlling the reaction temperature, an azeotrope of acetone and water is formed in the primary oxidation tank, thereby realizing the separation of chlorobenzene and acetone in the wastewater.

[0011] Another object of the present invention is to provide a wastewater treatment device containing high concentrations of chlorobenzene and acetone. The effluent from the primary oxidation tank enters the secondary catalytic oxidation tank, where oxidants and catalysts are added to deeply oxidize chlorobenzene, effectively improving the efficiency of photocatalytic oxidation and ensuring the ultraviolet oxidation effect.

[0012] The technical solution adopted by the present invention is:

[0013] The method for treating wastewater containing high concentrations of chlorobenzene and acetone comprises the following steps:

[0014] (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank;

[0015] (2) Primary oxidation: The water from the lower part of the homogenization tank enters the primary oxidation pool. Oxidant is added to the primary oxidation pool to cause ultraviolet light oxidation reaction. Acetone and water form an azeotrope. Chlorobenzene is decomposed into non-volatile intermediate products through the ultraviolet reactor, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation pool.

[0016] (3) Acetone recovery: The gas phase generated in the primary oxidation tank is sent to the condenser through the induced draft fan. The non-condensable gas at the top of the condenser is discharged to the tail gas treatment device for treatment, and the acetone condensate at the bottom is recycled;

[0017] (4) Secondary oxidation: The effluent from the middle of the primary oxidation pool enters the secondary catalytic oxidation pool, into which acid is added to adjust the pH, followed by the addition of a catalyst and an oxidant. The effluent from the lower part of the secondary catalytic oxidation pool enters the ultraviolet reactor, is irradiated by ultraviolet light, and then returns to the secondary catalytic oxidation pool for circulation, deeply oxidizing and decomposing chlorobenzene and its oxidation intermediates; 1 / 5 of the effluent from the secondary oxidation pool is returned to the primary oxidation pool to dilute the concentration of the oxidation intermediate benzoquinone pollutants, thereby ensuring the photocatalytic oxidation effect of the primary oxidation pool;

[0018] (5) Sedimentation: 4 / 5 of the effluent from the secondary catalytic oxidation tank is added with liquid caustic soda to adjust the pH value to neutral and then enters the sedimentation tank, where the catalyst produces a flocculation effect to precipitate the suspended organic matter;

[0019] (6) Drainage: The effluent from the sedimentation tank enters the monitoring tank and is discharged after testing and meeting the standards.

[0020] The hydraulic retention time in step (1) is 2 to 6 hours.

[0021] The primary oxidation pond in step (2) is made of an inner lining anti-corrosion material; the hydraulic retention time is 1 to 2 hours based on the influent; the oxidant is a hydrogen peroxide solution, and the mass ratio of the oxidant dosage (calculated as pure hydrogen peroxide) to the influent COD is (0.5:1) to (1:1).

[0022] The reaction temperature of the primary oxidation tank in step (2) is 55-60°C.

[0023] The ultraviolet reactor in step (2) contains a reaction tube, which is a medium-pressure ultraviolet reaction tube. The ultraviolet reactor includes a quartz sleeve area (a medium-pressure ultraviolet lamp is installed in the quartz sleeve) and a sewage area, wherein the primary oxidation sewage stays for 5 to 40 seconds. The ultraviolet reactor generates high heat during operation, and the cooler is used to control the temperature in the primary oxidation pool to avoid excessive temperature, which causes excessive decomposition of hydrogen peroxide. At the same time, the temperature in the primary oxidation pool can also be controlled to reach the boiling point of acetone.

[0024] In the step (4), the hydraulic retention time of the secondary catalytic oxidation tank is 1 to 2 hours; the oxidant is a hydrogen peroxide solution, and the mass ratio of the oxidant dosage (calculated as pure hydrogen peroxide) to the influent COD is (1 to 2):1; the acid solution is one of a sulfuric acid solution or a hydrochloric acid solution, and the added amount controls the pH value to be 2.3 to 3.0; the reaction temperature is 45 to 55° C.; the catalyst is ferric chloride, and the catalyst dosage (calculated as total iron) is 50 to 125 mg / L, and the dosage is calculated as total iron; the influent residence time of the reaction tube in the ultraviolet reactor is 5 to 20 seconds.

[0025] In the step (5), the hydraulic retention time is 0.5 to 1.5 hours; the alkali solution is one of a sodium hydroxide solution and a potassium hydroxide solution, and the pH value of the regulating tank is controlled to be 7.0 to 8.5; in the step (6), the hydraulic retention time is 1 to 3 hours.

[0026] The wastewater treatment device containing high concentrations of chlorobenzene and acetone comprises a homogenizing tank, which is connected to a secondary catalytic oxidation tank through a primary oxidation tank, which is connected to a monitoring tank through a sedimentation tank, a pipeline for entering the primary oxidation tank is connected between the homogenizing tank and the primary oxidation tank, a pipeline for exiting the secondary catalytic oxidation tank is connected between the secondary catalytic oxidation tank and the sedimentation tank, the pipeline for exiting the secondary catalytic oxidation tank is connected to the pipeline for entering the primary oxidation tank through a reflux pump, a secondary water outlet reflux pipeline is provided between the pipeline for exiting the secondary catalytic oxidation tank and the reflux pump, and a pipeline for exiting the reflux pump is provided between the reflux pump and the pipeline for entering the primary oxidation tank.

[0027] The primary oxidation tank is connected to a condensation tank through an induced draft fan, a condensation coil is arranged inside the condensation tank, a primary ultraviolet reactor is connected to the primary oxidation tank, and a secondary catalytic oxidation tank is connected to a secondary ultraviolet reactor.

[0028] The primary oxidation tank is connected to a primary oxidation tank feeding pipe, the secondary catalytic oxidation tank is connected to a secondary catalytic oxidation tank feeding pipe, the sedimentation tank is connected to a sedimentation tank feeding pipe, the bottom of the sedimentation tank is connected to a sedimentation tank slag discharge pipe, the monitoring tank is connected to a drainage pipe, and a cooler is arranged inside the primary oxidation tank.

[0029] The wastewater first enters the homogenization tank for buffering and homogenization, and then enters the primary oxidation tank from the bottom. Oxidants are added to the primary oxidation tank, and the ultraviolet reactor performs oxidation cycle treatment. Chlorobenzene undergoes oxidation reaction here and is quickly degraded into non-volatile intermediate products. Acetone and water form an azeotrope in the primary oxidation tank, which is discharged to the condenser tank through the upper pipeline of the primary oxidation tank. The acetone gas is condensed into liquid in the condenser tank. The non-condensable gas at the top of the condenser tank is discharged to the tail gas treatment device, and the condensate at the bottom is discharged to the biological treatment process as a supplementary carbon source. The effluent from the primary oxidation tank enters the secondary catalytic oxidation tank from the bottom and adjusts the pH. Oxidants and catalysts are added here, and the ultraviolet reactor performs oxidation cycle treatment to achieve deep degradation of chlorobenzene. The effluent from the secondary catalytic oxidation tank enters the secondary sedimentation tank after the pH value is adjusted. The effluent from the secondary sedimentation tank is discharged to the monitoring tank to meet the standards.

[0030] The principle of the present invention is:

[0031] The traditional photocatalytic oxidation is divided into two parts. The first part is to photolyze chlorobenzene, and the secondary photolysis product of chlorobenzene is oxidized and initially decomposed, and acetone is separated for recycling. The second part is to deeply decompose chlorobenzene to achieve standard discharge, and at the same time, part of the reflux dilutes the concentration of brown intermediate oxidation products in the first part of the wastewater to ensure the ultraviolet light oxidation effect of the first part.

[0032] Part 1: Add oxidant hydrogen peroxide to the primary photocatalytic oxidation tank. Hydrogen peroxide generates hydroxyl radicals after ultraviolet light irradiation. Chlorobenzene in the sewage forms non-volatile intermediate products, such as various chlorophenol isomers and benzoquinone mixtures, under the dual effects of ultraviolet light irradiation and hydroxyl radicals. By controlling the reaction temperature of the primary oxidation tank to 55-60°C, acetone and water form an azeotrope, and hydrogen peroxide decomposes to produce a large amount of gas, which carries acetone at the boiling point temperature up to the condensation tank. Then, chlorobenzene and acetone in the wastewater are separated. Acetone is then condensed and recovered in the condensation tank, realizing the recycling of acetone.

[0033] Part 2: Add oxidants and catalysts to the secondary oxidation pool. Since acetone has been separated in the primary oxidation pool, the secondary oxidation pool is only used to deeply degrade various chlorophenol isomers and benzoquinone mixture intermediates. This effectively improves the efficiency of photocatalytic oxidation and saves the amount of oxidants and catalysts. Benzoquinone products are yellow-brown in sewage, causing the color of the sewage to deepen and affect the effect of the photocatalytic reaction. Part of the effluent from the secondary oxidation pool is returned to the primary oxidation pool to dilute the concentration of benzoquinone pollutants and ensure the photocatalytic oxidation effect of the primary oxidation pool.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] (1) Based on the existing photocatalytic oxidation process, the present invention only adds an oxidant to the primary oxidation pool, where chlorobenzene is rapidly photolyzed into a non-volatile intermediate product. At the same time, by controlling the reaction temperature, an azeotrope of acetone and water is formed in the primary oxidation pool, thereby achieving separation of chlorobenzene and acetone in the wastewater.

[0036] (2) Chlorobenzene forms excited intermediate products after light oxidation in the primary oxidation tank, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation tank.

[0037] (3) The effluent from the primary oxidation tank enters the secondary catalytic oxidation tank, where oxidants and catalysts are added only for deep oxidation of chlorobenzene, effectively improving the efficiency of photocatalytic oxidation and ensuring the ultraviolet oxidation effect.

[0038] (4) The acetone in the wastewater forms an azeotrope with water in the primary oxidation tank and is subsequently condensed and recovered in a condensation tank, thereby achieving the recycling of acetone.

[0039] (5) The effluent from the secondary oxidation pool is partially returned to the primary oxidation pool to dilute the concentration of benzoquinone pollutants, thereby ensuring the photocatalytic oxidation effect of the primary oxidation pool, thus achieving the purpose of waste recycling. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a structural schematic diagram of a wastewater treatment device containing high concentrations of chlorobenzene and acetone according to the present invention;

[0041] In the figure: 1. homogenization tank; 2. primary oxidation tank; 3. secondary catalytic oxidation tank; 4. sedimentation tank; 5. monitoring tank; 6. condensation tank; 7. condensation coil; 8. primary UV reactor; 9. secondary UV reactor; 10. cooler; 11. pipeline for entering primary oxidation tank; 12. pipeline for exiting secondary catalytic oxidation tank; 13. secondary effluent return pipeline; 14. reflux pump; 15. pipeline for exiting reflux pump; 16. drainage pipeline; 17. feeding pipeline for primary oxidation tank; 18. feeding pipeline for secondary catalytic oxidation tank; 19. feeding pipeline for sedimentation tank; 20. slag discharge pipeline for sedimentation tank. DETAILED DESCRIPTION

[0042] The present invention is further described below with reference to the embodiments, but they do not limit the implementation of the present invention.

[0043] The analysis and testing methods and standards are shown in Table 1:

[0044] Table 1 Analysis and test methods and standards

[0045]

[0046] Note: B / C is the ratio of BOD to COD.

[0047] A wastewater treatment device containing high concentrations of chlorobenzene and acetone comprises a homogenizing tank 1, wherein the homogenizing tank 1 is connected to a secondary catalytic oxidation tank 3 through a primary oxidation tank 2, wherein the secondary catalytic oxidation tank 3 is connected to a monitoring tank 5 through a sedimentation tank 4, wherein a pipeline 11 for entering the primary oxidation tank is connected between the homogenizing tank 1 and the primary oxidation tank 2, wherein a pipeline 12 for exiting the secondary catalytic oxidation tank is connected between the secondary catalytic oxidation tank 3 and the sedimentation tank 4, wherein the pipeline 12 for exiting the secondary catalytic oxidation tank is connected to the pipeline 11 for entering the primary oxidation tank through a reflux pump 14, wherein a secondary effluent reflux pipeline 13 is provided between the pipeline 12 for exiting the secondary catalytic oxidation tank and the reflux pump 14, and wherein a reflux pump outlet pipeline 15 is provided between the reflux pump 14 and the pipeline 11 for entering the primary oxidation tank. The primary oxidation tank 2 is connected to a condensing tank 6 through an induced draft fan, wherein a condensing coil 7 is provided inside the condensing tank 6, wherein a primary ultraviolet reactor 8 is connected to the primary oxidation tank 2, and a secondary ultraviolet reactor 9 is connected to the secondary catalytic oxidation tank 3. The primary oxidation tank 2 is connected to a primary oxidation tank feeding pipe 17, the secondary catalytic oxidation tank 3 is connected to a secondary catalytic oxidation tank feeding pipe 18, the sedimentation tank 4 is connected to a sedimentation tank feeding pipe 19, a sedimentation tank slag discharge pipe 20 is connected below the sedimentation tank 4, the monitoring tank 5 is connected to a drainage pipe 16, and a cooler 10 is provided inside the primary oxidation tank 2.

[0048] The following examples all use the above-mentioned wastewater treatment device containing high concentrations of chlorobenzene and acetone to treat wastewater.

[0049] Example 1

[0050] Special rubber wastewater, chlorobenzene content 500-700 mg / L, acetone content 200-300 mg / L, COD 1300 mg / L.

[0051] The above wastewater treatment method comprises the following steps:

[0052] (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank. The hydraulic retention time is 6.0h, and the mixed wastewater is homogenized;

[0053] (2) Primary oxidation: The water from the lower part of the homogenization tank enters the primary oxidation pool. An oxidant is added to the primary oxidation pool to cause ultraviolet light oxidation reaction. Acetone and water form an azeotrope. Chlorobenzene is decomposed into non-volatile intermediate products through the ultraviolet reactor, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation pool. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the ratio of influent COD are 1:1, the hydraulic retention time is 1.0 h, and the reaction temperature is 60 ° C. Ultraviolet reactor: The ultraviolet light power is 500w / m 3 , the hydraulic retention time in the sewage area of ​​the reaction tube is 40S;

[0054] (3) Acetone recovery: The gas phase generated in the primary oxidation tank is sent to the condenser through the induced draft fan. The non-condensable gas at the top of the condenser is discharged to the tail gas treatment device for treatment, and the acetone condensate at the bottom is recycled; wherein, the hydraulic retention time is 3.0h;

[0055] (4) Secondary oxidation: The effluent from the middle of the primary oxidation tank enters the secondary catalytic oxidation tank, dilute hydrochloric acid solution is added to the secondary catalytic oxidation tank to adjust the pH to 2.3, and then ferric chloride solution and hydrogen peroxide solution are added. The preferred dosage of hydrogen peroxide solution (calculated as pure hydrogen peroxide) and the ratio of influent COD are 2:1, the hydraulic retention time is 1.0h, the reaction temperature is 55°C, and the total iron concentration in the oxidation tank is 125mg / L; the effluent from the lower part of the secondary catalytic oxidation tank enters the ultraviolet reactor for ultraviolet irradiation, and then returns to the secondary catalytic oxidation tank for circulation, so as to deeply oxidize and decompose chlorobenzene and its oxidation intermediates; the power of the ultraviolet reactor is 1000w / m 3 The hydraulic retention time of the sewage area in the reaction tube is 20S. One fifth of the effluent from the secondary oxidation tank flows back to the primary oxidation tank.

[0056] (5) Sedimentation: Sodium hydroxide solution is added to 4 / 5 of the effluent from the secondary catalytic oxidation tank to adjust the pH value to 8.5, and the effluent enters the sedimentation tank. The catalyst produces a flocculation effect to precipitate the suspended organic matter here; the hydraulic retention time is 1.5 h;

[0057] (6) Drainage: The effluent from the sedimentation tank enters the monitoring tank with a hydraulic retention time of 3.0 h and a pH value of 9.

[0058] Test results: the chlorobenzene content in the effluent of the monitoring pool is <0.2mg / L, the acetone content is 3-8mg / L, and the COD content is 26.9mg / L. The chlorobenzene and COD contents meet the enterprise's emission requirements. The acetone recovered by condensation is prepared into a 50mg / L solution, and the B / C is determined to be 0.41, which can be used as a high-quality carbon source for the biological denitrification process.

[0059] Example 2

[0060] Special rubber wastewater, chlorobenzene content 90 ~ 140mg / L, acetone content 50 ~ 80mg / L, COD320mg / L.

[0061] The above wastewater treatment method comprises the following steps:

[0062] (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank. The hydraulic retention time is 2.0h, and the mixed wastewater is homogenized;

[0063] (2) Primary oxidation: The water from the lower part of the homogenization tank enters the primary oxidation pool. An oxidant is added to the primary oxidation pool to cause ultraviolet light oxidation reaction. Acetone and water form an azeotrope. Chlorobenzene is decomposed into non-volatile intermediate products through the ultraviolet reactor, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation pool. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the ratio of influent COD are 0.5:1, the hydraulic retention time is 2.0 h, and the reaction temperature is 55 °C; Ultraviolet reactor: The ultraviolet light power is 500 w / m 3 , the sewage area of ​​the reaction tube has a hydraulic retention time of 5S;

[0064] (3) Acetone recovery: The gas phase generated in the primary oxidation tank is sent to the condenser through the induced draft fan. The non-condensable gas at the top of the condenser is discharged to the tail gas treatment device for treatment, and the acetone condensate at the bottom is recycled; wherein, the hydraulic retention time is 1.0h;

[0065] (4) Secondary oxidation: The effluent from the middle of the primary oxidation tank enters the secondary catalytic oxidation tank, dilute hydrochloric acid solution is added to the secondary catalytic oxidation tank to adjust the pH to 3.0, and then ferric chloride solution and hydrogen peroxide solution are added. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the COD of the influent are 1:1, the hydraulic retention time is 2.0 h, the reaction temperature is 45°C, and the total iron concentration in the oxidation tank is 50 mg / L; the effluent from the lower part of the secondary catalytic oxidation tank enters the ultraviolet reactor for ultraviolet irradiation, and then returns to the secondary catalytic oxidation tank for circulation, so as to deeply oxidize and decompose chlorobenzene and its oxidation intermediates; Ultraviolet reactor: the ultraviolet light power is 1000w / m 3 The hydraulic retention time in the sewage area of ​​the reaction tube is 5S. One-fifth of the effluent from the secondary oxidation tank flows back to the primary oxidation tank.

[0066] (5) Sedimentation: 4 / 5 of the effluent from the secondary catalytic oxidation tank is added with sodium hydroxide solution to adjust the pH value to 7, and then enters the sedimentation tank. The catalyst produces a flocculation effect to precipitate the suspended organic matter here; the hydraulic retention time is 0.5 h;

[0067] (6) Drainage: The effluent from the sedimentation tank enters the monitoring tank with a hydraulic retention time of 1.0 h and a pH value of 6.

[0068] Test results: The chlorobenzene content in the effluent of the monitoring pool is <0.2mg / L, the acetone content is 2-6mg / L, and the COD is 27.6mg / L. The chlorobenzene and COD contents meet the enterprise's emission requirements. The acetone recovered by condensation is prepared into a 50mg / L solution, and the B / C is determined to be 0.40, which can be used as a high-quality carbon source for the biological denitrification process.

[0069] Example 3

[0070] Special rubber wastewater, chlorobenzene content 260 ~ 330mg / L, acetone content 160 ~ 210mg / L, COD320mg / L.

[0071] The above wastewater treatment method comprises the following steps:

[0072] (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank. The hydraulic retention time is 4.0h, and the mixed wastewater is homogenized;

[0073] (2) Primary oxidation: The water from the lower part of the homogenization tank enters the primary oxidation pool. An oxidant is added to the primary oxidation pool to cause ultraviolet light oxidation reaction. Acetone and water form an azeotrope. Chlorobenzene is decomposed into non-volatile intermediate products through the ultraviolet reactor, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation pool. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the ratio of influent COD are 0.8:1, the hydraulic retention time is 1.5h, and the reaction temperature is 58°C; Ultraviolet reactor: The ultraviolet light power is 500w / m 3 , the hydraulic retention time in the sewage area of ​​the reaction tube is 30S;

[0074] (3) Acetone recovery: The gas phase generated in the primary oxidation tank is sent to the condenser through the induced draft fan. The non-condensable gas at the top of the condenser is discharged to the tail gas treatment device for treatment, and the acetone condensate at the bottom is recycled; wherein, the hydraulic retention time is 2.5h;

[0075] (4) Secondary oxidation: The effluent from the middle of the primary oxidation tank enters the secondary catalytic oxidation tank, dilute hydrochloric acid solution is added to the secondary catalytic oxidation tank to adjust the pH to 2.6, and then ferric chloride solution and hydrogen peroxide solution are added. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the ratio of influent COD are 1.5:1, the hydraulic retention time is 1.5h, the reaction temperature is 50°C, and the total iron concentration in the oxidation tank is 90mg / L; the effluent from the lower part of the secondary catalytic oxidation tank enters the ultraviolet reactor for ultraviolet irradiation, and then returns to the secondary catalytic oxidation tank for circulation, so as to deeply oxidize and decompose chlorobenzene and its oxidation intermediates; Ultraviolet reactor: the ultraviolet light power is 1000w / m 3 The hydraulic retention time in the sewage area of ​​the reaction tube is 15S. One-fifth of the effluent from the secondary oxidation tank flows back to the primary oxidation tank.

[0076] (5) Sedimentation: Sodium hydroxide solution is added to 4 / 5 of the effluent from the secondary catalytic oxidation tank to adjust the pH value to 8.5, and the effluent enters the sedimentation tank. The catalyst produces a flocculation effect to precipitate the suspended organic matter here; the hydraulic retention time is 1 hour;

[0077] (6) Drainage: The effluent from the sedimentation tank enters the monitoring tank with a hydraulic retention time of 2.0 h and a pH value of 7.

[0078] Test results: The chlorobenzene content in the effluent of the monitoring pool is <0.2mg / L, the acetone content is 4-8mg / L, and the COD content is 33.5mg / L. The chlorobenzene and COD contents meet the enterprise's emission requirements. The acetone recovered by condensation is prepared into a 50mg / L solution, and the B / C is determined to be 0.45, which can be used as a high-quality carbon source for the biological denitrification process.

[0079] Comparative Example 1

[0080] Special rubber wastewater, chlorobenzene content 500-700 mg / L, acetone content 200-300 mg / L, COD 1300 mg / L.

[0081] The above wastewater treatment method comprises the following steps:

[0082] (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank. The hydraulic retention time is 6.0h, and the mixed wastewater is homogenized;

[0083] (2) Photocatalytic oxidation: The effluent from the lower part of the homogenization tank enters the oxidation tank, dilute hydrochloric acid solution is added to the oxidation tank to adjust the pH to 2.3, and then ferric chloride solution and hydrogen peroxide solution are added. The preferred dosage of hydrogen peroxide solution (in terms of pure hydrogen peroxide) and the COD of the influent are 3:1, the hydraulic retention time is 3.0 h, the reaction temperature is 50°C, and the total iron concentration in the oxidation tank is 150 mg / L; the effluent from the lower part of the oxidation tank enters the ultraviolet reactor for ultraviolet irradiation, and then returns to the photocatalytic oxidation tank for circulation to deeply oxidize and decompose chlorobenzene and acetone; the power of the ultraviolet reactor is 1000 w / m 3 The hydraulic retention time in the sewage area of ​​the reaction tube is 40S.

[0084] (3) Sedimentation: Sodium hydroxide solution is added to the effluent from the oxidation tank to adjust the pH value to 8.5, and the effluent enters the sedimentation tank. The catalyst produces a flocculation effect to precipitate the suspended organic matter here; the hydraulic retention time is 1.5 h;

[0085] (4) Drainage: The effluent from the sedimentation tank enters the monitoring tank with a hydraulic retention time of 3.0 h and a pH value of 9. The effluent from the monitoring tank meets the discharge standards.

[0086] Test results: The chlorobenzene content in the effluent from the monitoring pool is <0.2mg / L, the acetone content is 15-20mg / L, and the COD content is 38.9mg / L. The chlorobenzene and COD contents meet the company's emission requirements.

[0087] The comparison results of the process parameters of Comparative Example 1 and Example 1 are shown in Table 1.

[0088] Table 1 Comparison of process parameters between comparative example 1 and embodiment 1

[0089]

[0090] When the existing photocatalytic oxidation process is used for treatment, chlorobenzene and acetone in sewage are not treated separately, the dosage of oxidant and catalyst is large, the reaction time is long, the acetone in sewage is deeply degraded, and it is not effectively recycled, and the operating cost is high. The dosage of oxidant and catalyst in the technology of the present invention is small, the oxidation time is shortened, the separated acetone solution has good biodegradability, and the oxidation efficiency and economy are better than the comparative process.

Claims

1. A method for treating wastewater containing high concentrations of chlorobenzene and acetone, characterized in that: The following steps are involved: (1) Homogenization: The wastewater enters the homogenization tank, and a water outlet is set at the bottom of the homogenization tank; (2) Primary oxidation: The water from the lower part of the homogenization tank enters the primary oxidation pool. Oxidant is added to the primary oxidation pool to cause ultraviolet light oxidation reaction. Acetone and water form an azeotrope. Chlorobenzene is decomposed into non-volatile intermediate products through the ultraviolet reactor, creating conditions for deep oxidation treatment in the secondary photocatalytic oxidation pool. (3) Acetone recovery: The gas phase generated in the primary oxidation tank is sent to the condenser through the induced draft fan. The non-condensable gas at the top of the condenser is discharged to the tail gas treatment device for treatment, and the acetone condensate at the bottom is recycled; (4) Secondary oxidation: The effluent from the middle of the primary oxidation pool enters the secondary catalytic oxidation pool, into which acid is added to adjust the pH, followed by the addition of a catalyst and an oxidant. The effluent from the lower part of the secondary catalytic oxidation pool enters the ultraviolet reactor, is irradiated by ultraviolet light, and then returns to the secondary catalytic oxidation pool for circulation, deeply oxidizing and decomposing chlorobenzene and its oxidation intermediates; 1 / 5 of the effluent from the secondary oxidation pool is returned to the primary oxidation pool to dilute the concentration of the oxidation intermediate benzoquinone pollutants, thereby ensuring the photocatalytic oxidation effect of the primary oxidation pool; (5) Sedimentation: 4 / 5 of the effluent from the secondary catalytic oxidation tank is added with liquid caustic soda to adjust the pH value to neutral and then enters the sedimentation tank, where the catalyst produces a flocculation effect to precipitate the suspended organic matter; (6) Drainage: The effluent from the sedimentation tank enters the monitoring tank and is discharged after testing and meeting the standards.

2. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: The hydraulic retention time in step (1) is 2 to 6 hours.

3. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: The primary oxidation pond in step (2) is made of an inner lining anti-corrosion material; the hydraulic retention time is 1 to 2 hours based on the influent; the oxidant is a hydrogen peroxide solution, and the mass ratio of the oxidant dosage to the influent COD is (0.5:1) to (1:1).

4. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: The reaction temperature of the primary oxidation tank in step (2) is 55-60°C.

5. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: The ultraviolet reactor in the step (2) contains a reaction tube, which is a medium-pressure ultraviolet light reaction tube. The ultraviolet reactor includes a quartz sleeve area and a sewage area, wherein the primary oxidation sewage stays for 5 to 40 seconds.

6. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: In the step (4), the hydraulic retention time of the secondary catalytic oxidation tank is 1 to 2 hours; the oxidant is a hydrogen peroxide solution, and the mass ratio of the oxidant dosage to the influent COD is (1 to 2):1; the acid solution is one of a sulfuric acid solution or a hydrochloric acid solution, and the added amount controls the pH value to be 2.3 to 3.0; the reaction temperature is 45 to 55° C.; the catalyst is ferric chloride, and the catalyst dosage is 50 to 125 mg / L, and the dosage is calculated based on total iron; the influent residence time of the reaction tube in the ultraviolet reactor is 5 to 20 seconds.

7. The method for treating wastewater containing high concentrations of chlorobenzene and acetone according to claim 1, characterized in that: In the step (5), the hydraulic retention time is 0.5 to 1.5 hours; the alkali solution is one of a sodium hydroxide solution and a potassium hydroxide solution, and the pH value of the regulating tank is controlled to be 7.0 to 8.5; in the step (6), the hydraulic retention time is 1 to 3 hours.

8. A device used in the method for treating wastewater containing high concentrations of chlorobenzene and acetone according to any one of claims 1 to 7, characterized in that: The invention comprises a homogenizing tank (1), wherein the homogenizing tank (1) is connected to a secondary catalytic oxidation tank (3) via a primary oxidation tank (2), the secondary catalytic oxidation tank (3) is connected to a monitoring tank (5) via a sedimentation tank (4), a pipeline (11) for entering the primary oxidation tank is connected between the homogenizing tank (1) and the primary oxidation tank (2), a pipeline (12) for exiting the secondary catalytic oxidation tank is connected between the secondary catalytic oxidation tank (3) and the sedimentation tank (4), the pipeline (12) for exiting the secondary catalytic oxidation tank is connected to the pipeline (11) for entering the primary oxidation tank via a reflux pump (14), a secondary water outlet reflux pipeline (13) is provided between the pipeline (12) for exiting the secondary catalytic oxidation tank and the reflux pump (14), and a reflux pump outlet pipeline (15) is provided between the reflux pump (14) and the pipeline (11) for entering the primary oxidation tank.

9. The device according to claim 8, characterized in that The primary oxidation tank (2) is connected to a condensation tank (6) via an induced draft fan, a condensation coil (7) is provided inside the condensation tank (6), a primary ultraviolet reactor (8) is connected to the primary oxidation tank (2), and a secondary catalytic oxidation tank (3) is connected to a secondary ultraviolet reactor (9).

10. The device according to claim 8, characterized in that The primary oxidation tank (2) is connected to a primary oxidation tank feeding pipeline (17), the secondary catalytic oxidation tank (3) is connected to a secondary catalytic oxidation tank feeding pipeline (18), the sedimentation tank (4) is connected to a sedimentation tank feeding pipeline (19), the sedimentation tank (4) is connected to a sedimentation tank slag discharge pipeline (20), the monitoring tank (5) is connected to a drainage pipeline (16), and a cooler (10) is provided inside the primary oxidation tank (2).

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