Nitrile rubber production sewage treatment process and device

Abstract

The invention discloses a nitrile rubber production sewage treatment process and device, and belongs to the technical field of synthetic rubber sewage treatment. According to the technical scheme, the sewage treatment device comprises a homogenizing tank, a two-stage air floatation tank, a high-density sedimentation tank I, a nitrile removal and cyanide breaking unit, an adsorption sedimentation tank, a hydrolysis acidification tank, a denitrification tank, an aeration tank, a secondary sedimentation tank, a denitrification filter tank, an engineering bacterium biological filter tank and a sedimentation filter tank which are sequentially connected through pipelines; the sewage treatment process comprises the following steps: 1) pretreating glue-containing sewage; the invention provides a nitrile-butadiene rubber production device sewage treatment method, which comprises the following steps of 1) nitrile removal and cyanogen breaking treatment, 3) biochemical treatment, and 4) sewage up-to-standard deep treatment.The nitrile-butadiene rubber production device sewage treatment method is safe and reliable in operation, can perform efficient denitrification and decarbonization treatment on all sewage in a nitrile-butadiene rubber production device area, enables the discharged sewage to reach the GB31571-2015 direct discharge standard, provides a tail gas discharge treatment scheme, and radically solves the problem of environmental pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of synthetic rubber wastewater treatment, and in particular relates to a process and a device for treating wastewater produced by nitrile rubber. Background Art

[0002] Nitrile rubber (NBR) is a copolymer made by emulsion polymerization of butadiene and acrylonitrile, followed by coagulation, washing and dehydration. NBR has the characteristics of oil resistance, heat resistance and excellent mechanical properties, and is widely used in the fields of automobiles, aerospace, oil extraction, chemicals, textiles, wires and cables, printing and food packaging. In the synthesis process of NBR, butadiene and acrylonitrile are used as raw materials, and various additives such as initiators, emulsifiers, electrolytes, regulators, dispersants and terminators are added. Therefore, the sewage containing incompletely recovered butadiene, acrylonitrile monomers and various additives has complex water quality, high COD and oligomer content, strong toxicity and is difficult to biodegrade, making it difficult to treat. If it enters the biochemical treatment system directly without pretreatment, it will cause serious impact on the sewage field and even pollute the environment.

[0003] There are few reports on the treatment process of NBR production wastewater, which mainly focus on removing residual acrylonitrile and sodium 1,2-dibutyl-6-naphthalenesulfonate (pulped powder) after monomer recovery. At present, there is no mature process that can treat nitrile rubber wastewater to meet the direct discharge standard of GB31571-2015, that is, to achieve the emission control indicators of COD ≤ 30 mg / L, ammonia nitrogen ≤ 2 mg / L, total nitrogen ≤ 7 mg / L, TOC ≤ 15 mg / L, and total phosphorus ≤ 0.5 mg / L.

[0004] Chinese invention patent CN104556538A relates to a method for treating acrylonitrile with a low concentration: under the conditions of polymerization reaction, nitrile-containing and latex-containing wastewater is mixed with a polymerization initiator to make acrylonitrile and oligomers undergo polymerization reaction, then the wastewater is subjected to magnetic flocculation, and finally the activated sludge method is used for biochemical treatment. The final discharged wastewater has basically no residual acrylonitrile, COD < 50mg / L, and ammonia nitrogen < 5mg / L. Through practical application, it was found that there is a problem of incomplete sodium persulfate flocculation of polyacrylonitrile, and the entire treatment process always has residual acrylonitrile with a concentration of 8-19mg / L, which not only affects the stable operation of the biochemical system, but also causes secondary pollution to the environment.

[0005] The treatment method disclosed in the Chinese invention patent CN104556539B is as follows: the wastewater produced by nitrile rubber is mixed with an excess of sulfite to convert acrylonitrile in the wastewater produced by nitrile rubber into sodium cyanoethyl sulfonate which is not volatile, and then H2O2 and ferrous sulfate solution are added to the water for advanced oxidation treatment with Fenton reagent; after solid-liquid separation of the sewage, the supernatant is mixed with activated sludge for biochemical treatment. After treatment by the invention method, the acrylonitrile content in the water is low, the COD value is less than 50mg / L, and the ammonia nitrogen content is less than 5mg / L. Although this method makes acrylonitrile in the water undetectable, -CN with biological toxicity still exists, and the B / C value of sodium cyanoethyl sulfonate of different concentrations is 0.1-0.23. The difficulty of sewage treatment and biodegradability have not been essentially changed, and a large amount of iron mud is produced when the sewage is treated with Fenton reagent, which brings secondary pollution to the environment.

[0006] Zhang Jieliang's article "Technology and Equipment Improvement for Nitrile Rubber Wastewater Treatment" points out that the combined process of "coagulation sedimentation-microelectrolysis-catalytic oxidation-neutralization" was used to treat the wastewater from the latex coagulation unit of the nitrile rubber plant of Lanzhou Petrochemical Company's rubber plant. After treatment, the removal rate of the powder was ≥70%, the COD removal rate was ≥30%, and the SS removal rate was ≥80%. The core of this process is the Fe / C microelectrolysis-Fenton combined process. Due to the different production synthesis and coagulation processes of nitrile rubber, the different water quality components, the presence of solid rubber residue, latex, and suspended impurities in the water, and the entrainment of foam during aeration, the microelectrolysis reactor filler is blocked, affecting the long-term operation of the device. The promotion and application of the process has certain limitations.

[0007] In summary, most of the existing nitrile rubber wastewater treatment processes have the disadvantages of poor effluent quality, which cannot meet the direct discharge standard of GB31571-2015, harsh reaction conditions in the treatment unit that are difficult to control, low treatment efficiency, production of toxic by-products, secondary pollution to the environment, and difficulty in achieving industrialization. Summary of the invention

[0008] The present invention provides a process and device for treating wastewater from nitrile rubber production, which overcomes the problems of poor water quality of existing process wastewater, the generation of toxic byproducts, and secondary pollution to the environment, and provides a safe and reliable operation method, which can effectively denitrify and decarbonize all wastewater in the nitrile rubber production device area, so that the discharged wastewater meets the direct discharge standard of GB31571-2015. At the same time, a tail gas emission treatment solution is provided to fundamentally solve the problem of environmental pollution.

[0009] The technical solution of the present invention is: In the first aspect, a nitrile rubber production wastewater treatment device is disclosed, including a homogenizing tank, a two-stage flotation tank, a high-density sedimentation tank, a nitrile and cyanide removal unit, an adsorption sedimentation tank, a hydrolysis acidification tank, a denitrification tank, an aeration tank, a secondary sedimentation tank, a denitrification filter, an engineering bacteria biofilter and a sedimentation filter tank, which are connected in sequence through pipelines; the homogenizing tank is provided with a monomer recovery unit drainage inlet pipeline and a condensation unit acid water inlet pipeline; a flocculant inlet pipeline is provided on the pipeline between the homogenizing tank and the two-stage flotation tank, and the two-stage flotation tank and the high-density An alkali inlet pipeline 1 is arranged on the pipeline between the high-density sedimentation tank 1, and an alkaline water inlet pipeline of the condensation unit is arranged on the pipeline between the nitrile removal and cyanide breaking unit and the adsorption sedimentation tank; a nitrification liquid return pipeline is also arranged between the aeration tank and the denitrification tank; a sludge return pipeline is also arranged between the secondary sedimentation tank and the adsorption sedimentation tank; a high-density sedimentation tank 2 and a circulating water sewage inlet pipeline are also connected on the pipeline between the hydrolysis acidification tank and the denitrification tank through pipelines, and a desalted water concentrate inlet pipeline and an alkali inlet pipeline 2 are arranged in the high-density sedimentation tank 2.

[0010] Preferably, the homogenization tank is also connected to an accident tank.

[0011] Preferably, the homogenization tank, the accident tank, the two-stage flotation tank, the high-density sedimentation tank and the nitrile removal and cyanide breaking unit are all connected to the waste gas absorption tower through pipelines; an absorption liquid recycling pipeline is also provided between the waste gas absorption tower and the nitrile removal and cyanide breaking unit, and the absorption liquid recycling pipeline is used to transport saturated sodium cyanoethyl sulfonate.

[0012] Preferably, the nitrile removal and cyanide destruction unit is provided with a hydrolysis adjustment tank, a photocatalytic reaction tank and an oxidation reactor.

[0013] In a second aspect, a process for treating wastewater produced by nitrile rubber is disclosed, comprising the following steps: 1) Pretreatment of rubber-containing wastewater: The alkaline drainage discharged from the acrylonitrile monomer recovery unit and the acidic water from the coagulation unit are mixed and then enter the homogenization tank, the pH value is adjusted to neutral to alkaline, flocculants and coagulants are added, and then enter the two-stage flotation tank. The effluent from the two-stage flotation tank enters the high-density sedimentation tank 1 to remove suspended impurities and oligomers in the water. Alkali solution is added to the effluent from the high-density sedimentation tank 1 to adjust the pH; 2) Nitrile removal and cyanide breaking treatment: including hydrolysis under alkaline conditions and advanced oxidation reaction under acidic conditions. As soon as the water comes out of the high-density sedimentation tank, alkali is added to adjust the pH, hydrogen peroxide is added, and the water enters the hydrolysis adjustment tank for homogenization adjustment, and then enters the photocatalytic reaction tank for hydrolysis reaction. During the reaction, the total cyanide content, ammonia nitrogen concentration and hydrogen peroxide residue are monitored in real time. When the total cyanide monitoring value of the sewage shows 0 and the ammonia nitrogen concentration rises sharply, alkali is no longer added to control the pH value. As the reaction proceeds, the pH of the wastewater drops to neutral to slightly acidic, and the sewage enters the oxidation reactor under acidic conditions for advanced oxidation reaction; 3) Biochemical treatment: After the alkaline water discharged from the condensation unit is mixed with the acidic water discharged after the nitrile and cyanide removal treatment, a neutralization reaction occurs and the water is collected together in the adsorption sedimentation tank for adsorption and sedimentation. After entering the hydrolysis acidification tank, the macromolecular organic matter in the sewage is degraded into small molecular organic matter. The effluent from the hydrolysis acidification tank flows to the denitrification tank by gravity. The subsequent effluent return liquid from the aeration tank, the circulating water from the plant area, and the desalted water after adding alkali to remove hardness are fully mixed at the water inlet of the denitrification tank to remove the total nitrogen in the sewage. The effluent from the denitrification tank enters the aeration tank for carbonization reaction and nitrification reaction to remove COD in the sewage, and convert ammonia nitrogen into nitrate and nitrite, and then precipitates in the secondary sedimentation tank; 4) Deep treatment of sewage to meet standards: The sewage that has been precipitated in the secondary sedimentation tank enters the denitrification filter, engineered bacteria biofilter and sedimentation filter in turn to further reduce the concentrations of total organic carbon, nitrate nitrogen and total nitrogen in the sewage to ensure that the sewage discharged from the system meets the standards stably.

[0014] Preferably, the neutral to alkaline pH range in step 1) is 6-9, and alkali solution is added to the effluent of the high-density sedimentation tank to adjust the pH to 10-12.5, preferably 10.5-12.

[0015] Preferably, in step 2), alkali is added to adjust the pH>10.5, the pH of the hydrolysis reaction in the photocatalytic reaction tank is>10.5, the reaction temperature is 40-60°C, preferably 45-55°C, the reaction time is 2-5h, preferably 2.5-4.5h, the neutral to slightly acidic pH range in step 2) is 4.5-6.5, and the concentration of hydrogen peroxide added is 1500-2500mg / L.

[0016] Preferably, the pH of the neutralization reaction in step 3) is 6-9, the residence time in the adsorption sedimentation tank is 0.5-1h, and the residence time in the hydrolysis acidification tank is 20-48h, preferably 24-45h.

[0017] Preferably, the process further comprises collecting and treating the tail gas containing nitrile, specifically: the tail gas containing acrylonitrile volatilized in the homogenizing tank, the two-stage flotation tank, the high-density sedimentation tank 1, the nitrile removal and cyanide breaking unit and the accident tank enters the waste gas absorption tower for treatment; the absorption liquid (saturated sodium cyanoethyl sulfonate solution) in the waste gas absorption tower is refluxed into the nitrile removal and cyanide breaking unit.

[0018] The specific principles are: 1) Pretreatment of rubber-containing wastewater: The alkaline stripping wastewater discharged from the acrylonitrile monomer recovery unit and the acidic water from the coagulation unit are mixed and then enter the homogenization tank. The main pollutants contained in the wastewater include acrylonitrile, residual production aids, rubber residues and incompletely coagulated latex particles. The residence time (HTR) in the homogenization tank is 10-20h, preferably 12-18h. The pH of the wastewater is adjusted to neutral to alkaline, and flocculants and coagulants are added. The wastewater enters the two-stage flotation treatment unit to remove impurities and latex in the water. The effluent of the two-stage flotation tank enters the high-density sedimentation tank 1 to remove suspended impurities and oligomers in the water, thereby reducing the turbidity of the wastewater and improving the penetration rate of ultraviolet light. At the same time, it avoids the adhesion of rubber oligomers to the surface of the lamp tube under the action of high temperature, creating good conditions for ultraviolet photocatalytic reaction under alkaline conditions; the effluent of the high-density sedimentation tank 1 is added with alkali solution in the pipeline for pH adjustment, and the pH is controlled at 10-12.5, preferably 10.5-12, to prepare for the elimination of organic matter containing -CN in the wastewater.

[0019] 2) Nitrile and cyanide removal treatment: including hydrolysis under alkaline conditions and advanced oxidation reaction under acidic conditions. The equipment used includes hydrolysis adjustment tank, photocatalytic reaction tank and oxidation reactor. The main pollutants treated include: acrylonitrile, residual production aids and adsorption liquid containing sodium cyanoethyl sulfonate; ultraviolet light catalytic reaction under alkaline conditions, under the combined action of hydrogen peroxide and ultraviolet light, sodium cyanoethyl sulfonate in nitrile rubber wastewater is hydrolyzed into sodium acrylamide sulfonate or sodium acrylic acid sulfonate, or a mixture of the two, effectively reducing the toxicity of organic nitrile compounds and cyanide compounds, and improving the biodegradability of wastewater. In the early stage of ultraviolet light catalytic reaction under alkaline conditions, caustic soda is added to the water to maintain pH>10.5, and the wastewater reaction temperature is 40-60℃, preferably 45-55℃. During the reaction, the three main control parameters of total cyanide content, ammonia nitrogen concentration and hydrogen peroxide residue are monitored in real time. When the total cyanide monitoring value of the sewage shows 0, the ammonia nitrogen concentration rises sharply. At this time, alkali solution is no longer added to control the pH value. As the reaction proceeds, the pH of the wastewater will gradually drop to neutral to slightly acidic, and the sewage enters the advanced oxidation COD reduction treatment under acidic conditions. If there are still residual cyanide compounds during the reaction, hydrogen peroxide is added to continue the photohydrolysis reaction until all organic nitrile compounds and cyanide compounds in the water are hydrolyzed, and then it can enter the subsequent treatment unit to avoid the release of highly toxic HCN during the advanced oxidation reaction under acidic conditions. The photohydrolysis reaction time is 2-5h, preferably 2.5-4.5h.

[0020] The oxidation reactor is filled with filter material that can reduce COD. The filter material is a common commercially available filter material with carbon and iron components. It has solid particles with a certain strength and hardness and a porous structure. Under acidic conditions, it can form a primary battery and undergo a redox reaction with the difficult-to-degrade organic matter in the wastewater to reduce COD. The porous structure formed during the filter material processing has a strong adsorption effect, which increases the degradation area and residence time of organic matter, thereby eliminating the chromaticity of organic wastewater and improving the biodegradability of wastewater.

[0021] During operation, the drainage from the alkaline hydrolysis stage is neutral to slightly acidic. A proper amount of acid is added to adjust the pH to 2-4, preferably 2.5-3.4; the reaction time is 20-70 minutes, preferably 30-60 minutes. After passing through the packing bed through the distribution plate at the bottom of the oxidation reactor, it is discharged from the water collection tank at the top. The large amount of gas and residual hydrogen peroxide contained in the water flushes the surface of the packing during the flow, which not only meets the requirements of micro-aeration, but also avoids the formation of a passivation film on the surface of the filter material. In addition, the decomposition of hydrogen peroxide provides more ·OH, causing chain scission and degradation of organic macromolecules. The COD removal rate is greater than 70%, the ammonia nitrogen concentration increases significantly, and the biodegradability is significantly improved, creating good conditions for subsequent biochemical treatment.

[0022] 1) Biochemical treatment: The biochemical treatment unit uses the conventional A1 / A2 / O biochemical treatment combined process. After the alkaline water discharged from the coagulation unit is mixed with the acidic water discharged after the nitrile removal and cyanide breaking treatment, the pH value is 6-9 and they are collected together in the sludge adsorption sedimentation tank. A large number of microorganisms first quickly intercept and adsorb the particulate matter and colloidal matter in the influent water, and then enter the hydrolysis acidification tank after a residence time of 0.5-1h. The residence time of the hydrolysis acidification tank is 20-48h, preferably 24-45h. The macromolecular organic matter in the sewage is degraded into small molecular organic matter by the hydrolysis acidification bacteria, further improving the biodegradability of the sewage.

[0023] The small amount of Fe ions brought out during the oxidation stage of the advanced oxidation tank is converted into Fe(OH)3 precipitate in an alkaline environment, which has a flocculation and precipitation effect on the pollutants in the water and the colloid particles brought out during the rubber alkali washing process, increasing the sedimentation performance of the colloid particles and avoiding the floating of sludge due to the floating of colloid particles. In addition, the dissolved oxygen in the water drops rapidly to below 0.2 mg / L after being adsorbed by the sludge, preventing the high dissolved oxygen and large molecular colloid particles from directly entering the hydrolysis and acidification tank, causing the activated sludge with anaerobic microorganisms as the main flora to lose its acidification function, thereby reducing the treatment efficiency of the subsequent sewage treatment system.

[0024] After activated sludge adsorption and hydrolysis acidification treatment, the nitrile rubber wastewater is fully mixed with the effluent return liquid of the aeration tank, the circulating water wastewater in the plant area, and the desalted water concentrated water after hardness removal and filtration at the water inlet of the denitrification tank. Through the denitrification reaction, the nitrate and nitrite in the sewage are converted into nitrogen gas to achieve the purpose of removing total nitrogen. The effluent of the denitrification tank enters the biochemical aeration tank for carbonization reaction and nitrification reaction to remove COD in the sewage, and convert ammonia nitrogen into nitrate and nitrite. This water inlet method can prolong the hydrolysis and acidification time of the difficult-to-degrade organic matter in the nitrile rubber wastewater and improve the treatment effect of the difficult-to-degrade organic matter. After precipitation in the secondary sedimentation tank, it enters the standard discharge and enters the deep treatment unit.

[0025] 4) Deep treatment of sewage to meet standards: The nitrile rubber sewage deep treatment unit adopts the combined process of "denitrification filter + ABR engineering bacteria biofilter + sedimentation filtration" to further reduce the TOC (total organic carbon), nitrate nitrogen and total nitrogen concentrations in the sewage to ensure that the sewage discharged from the system meets the standards stably.

[0026] 5) Collection and treatment of nitrile-containing tail gas: During the treatment process of nitrile rubber wastewater, tail gas containing acrylonitrile will volatilize, which will cause serious harm to the surrounding environment of the factory and the health of operators. Taking full consideration of the absorption and treatment of tail gas, a waste gas absorption tower is set up, and sodium sulfite solution is used to absorb and treat tail gas containing acrylonitrile and cyanide to generate sodium cyanoethyl sulfonate with high solubility and low volatility. The absorption liquid regularly monitors the concentration and pH value of sodium sulfite, and after adsorption saturation, it is collected in the hydrolysis adjustment tank for pollutant treatment, fundamentally eliminating the impact of acrylonitrile.

[0027] Compared with the prior art, the present invention has the following beneficial effects: 1. The wastewater treatment process for the production of nitrile rubber of the present invention adopts the "diversion and quality separation" treatment method for the first time to treat various wastewaters from different process sections of nitrile rubber with different pollutant types, properties and concentrations. The treatment process is highly targeted and has a high pollutant removal rate. All wastewater discharged from the nitrile rubber device area is efficiently denitrified and decarbonized, including: wastewater from nitrile rubber production, circulating water wastewater, concentrated water produced in the process of manufacturing desalted water, and drainage from the accident pool. Multiple indicators such as COD, total nitrogen, ammonia nitrogen, TOC, and total phosphorus of the discharged wastewater meet the direct discharge standard of GB31571-2015.

[0028] 2. The combination of alkaline hydrolysis and acidic oxidation advanced oxidation processes in the present invention overcomes the shortcomings of the prior art. The alkaline hydrolysis stage removes cyanide and nitrile-containing organic matter in the water, and the acidic advanced oxidation stage does not produce highly toxic HCN, which significantly improves the biodegradability of wastewater. In addition, there is no need to lay an aeration device in the oxidation reactor, which reduces the investment and volume of the equipment. The degraded COD filter material is used in the advanced oxidation stage. After the sewage is flotated and filtered, there are fewer suspended impurities in the water, and there will be no foam entrainment or reactor clogging during the operation of the device. The hydrogen peroxide added to the water has no residue and is fully involved in the degradation of pollutants. The utilization rate of the reagent is high, and the operation is simple and easy to control. The operating effect is better than the existing water treatment process.

[0029] 3. The technical solution provided by the technical solution of the present invention sets up tail gas adsorption treatment facilities, provides a solution to fundamentally solve the problem of environmental pollution, has good industrial application prospects, and can be used for industrial governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the nitrile rubber wastewater treatment device provided by the present invention.

[0031] In the figure, 1. homogenization tank; 2. two-stage flotation tank; 3. high-density sedimentation tank 1; 4. nitrile removal and cyanide breaking unit; 5. adsorption sedimentation tank; 6. hydrolysis acidification tank; 7. denitrification tank; 8. aeration tank; 9. secondary sedimentation tank; 10. denitrification filter tank; 11. engineering bacteria biofilter tank; 12. sedimentation filter tank; 13. waste gas absorption tower; 14. accident tank; 15. monomer recovery unit drainage inlet pipeline; 16. coagulation unit acidic water inlet pipeline; 17. flocculant inlet pipe; 18. alkali inlet pipeline 1; 19. coagulation unit alkaline water inlet pipeline; 20. nitrification liquid reflux pipeline; 21. sludge reflux pipeline; 22. circulating water sewage inlet pipeline; 23. desalted water concentrate inlet pipeline; 24. alkali inlet pipeline 2; 25. high-density sedimentation tank 2; 26. absorption liquid reuse pipeline. DETAILED DESCRIPTION

[0032] The following embodiments all adopt the nitrile rubber production wastewater treatment device, which specifically includes a homogenization tank 1, a two-stage flotation tank 2, a high-density sedimentation tank 3, a nitrile removal and cyanide breaking unit 4, an adsorption sedimentation tank 5, a hydrolysis acidification tank 6, a denitrification tank 7, an aeration tank 8, a secondary sedimentation tank 9, a denitrification filter 10, an engineering bacteria biofilter 11 and a sedimentation filter 12 connected in sequence by pipelines; The homogenizing tank 1 is provided with a monomer recovery unit drainage inlet pipeline 15 and a condensation unit acid water inlet pipeline 16, and the homogenizing tank 1 is also connected to the accident tank 14; the homogenizing tank 1, the accident tank 14, the two-stage flotation tank 2, the high-density sedimentation tank 3 and the nitrile removal and cyanide breaking unit 4 are all connected to the waste gas absorption tower 13 through pipelines; an absorption liquid recycling pipeline 26 is also provided between the waste gas absorption tower 13 and the nitrile removal and cyanide breaking unit 4.

[0033] A flocculant inlet pipe 17 is provided on the pipeline between the homogenization tank 1 and the two-stage air flotation tank 2, an alkali inlet pipe 24 is provided on the pipeline between the two-stage air flotation tank 2 and the high-density sedimentation tank 1 3, and a coagulation unit alkaline water inlet pipe 19 is provided on the pipeline between the nitrile removal and cyanide breaking unit 4 and the adsorption sedimentation tank 5; The nitrile removal and cyanide destruction unit 4 is provided with a hydrolysis adjustment tank, a photocatalytic reaction tank and an oxidation reactor.

[0034] A nitrification liquid return pipeline 20 is also provided between the aeration tank 8 and the denitrification tank 7; a sludge return pipeline 21 is also provided between the secondary sedimentation tank 9 and the adsorption sedimentation tank 5; The pipeline between the hydrolysis acidification tank 6 and the denitrification tank 7 is also connected to a high-density sedimentation tank 25 and a circulating water sewage inlet pipeline 22 through a pipeline. The high-density sedimentation tank 25 is provided with a desalted water concentrated water inlet pipeline 23 and an alkali inlet pipeline 24.

[0035] Example 1 From a monomer recovery unit of a nitrile rubber wastewater treatment plant 10m 3 / h of alkaline drainage and 20m3 / h from the condensation unit 3 / h of acidic condensation water, the pH value was adjusted to 7.8 and entered the homogenization tank 1. It stayed in the homogenization tank 1 for 12 hours to precipitate and remove some rubber residues and incompletely condensed latex particles. The COD of the influent of the homogenization tank 1 was 880mg / L, TOC was 320mg / L, total nitrogen was 100mg / L, and ammonia nitrogen was not detected.

[0036] The effluent of homogenization tank 1 was added with flocculant PAC at a concentration of 100 mg / L and coagulant PAM at a concentration of 3 mg / L, and then entered the two-stage flotation treatment tank including vortex flotation and dissolved air flotation. After the impurities were removed from the effluent of the two-stage flotation treatment tank, it flowed into the high-density sedimentation tank 3 by gravity, and the suspended impurities and oligomers in the water were further removed. The turbidity was reduced from 10 NTU to below 3 NTU, achieving the purpose of improving the penetration rate of ultraviolet light, and at the same time avoiding the adhesion of rubber oligomers to the surface of the lamp tube of the photocatalytic reactor under the action of high temperature. The effluent of high-density sedimentation tank 3 was added with alkali solution in the pipeline for pH adjustment, and the pH was controlled to 10.5, creating good conditions for the operation of nitrile removal and cyanide breaking unit 4. COD of the effluent of high-density sedimentation tank 3: 506 mg / L, TOC: 180 mg / L, total nitrogen: 98 mg / L, ammonia nitrogen: not detected.

[0037] Since the wastewater treated by the homogenization tank 1, the two-stage flotation tank 2, the high-density sedimentation tank 3 and the nitrile removal and cyanide breaking unit 4 contains incompletely recovered acrylonitrile gas and other -CN-containing compounds, the tail gas containing acrylonitrile will be volatilized during the stirring and aeration process, which will cause serious harm to the surrounding environment of the factory and the health of the operators. Therefore, the tail gas from the above-mentioned treatment units is collected centrally and sent to the waste gas absorption tower 13 for harmless treatment. In the waste gas absorption tower 13, a 15% sodium sulfite solution is used to absorb and treat the tail gas containing acrylonitrile and cyanide to generate sodium cyanoethyl sulfonate with high solubility and low volatility. The absorption liquid regularly monitors the concentration and pH value of sodium sulfite. After adsorption saturation, it is collected into the hydrolysis adjustment tank of the nitrile removal and cyanide breaking unit 4 and mixed with 30m 3 / hThe pre-treated sewage is mixed and then treated together for nitrile removal and cyanide breaking to fundamentally eliminate the impact of acrylonitrile.

[0038] The effluent from the high-density sedimentation tank 3 enters the nitrile removal and cyanide breaking treatment, which includes hydrolysis under alkaline conditions and advanced oxidation reactions under acidic conditions. The effluent from the high-density sedimentation tank 3 has sewage COD: 1060mg / L, TOC: 420mg / L, total nitrogen: 236mg / L, and ammonia nitrogen: not detected. Alkali solution is added to adjust the pH value to 10.5, and the concentration of hydrogen peroxide added is 1500mg / L. It enters the hydrolysis adjustment tank for homogenization adjustment, and the residence time is 3h. The effluent from the hydrolysis adjustment tank then enters the UV / H2O2 photocatalytic reaction tank to improve the biodegradability of the wastewater. The ultraviolet light-promoted hydrolysis reaction temperature is 45°C and the reaction time is 2.5h. 2h after the start of the reaction, the change of pH value was monitored and alkali solution was continuously added to control the pH at 10.5-11.0, and the total cyanide and ammonia nitrogen contents in the water were monitored. When the total cyanide monitoring value of the sewage showed 0, the concentration of ammonia nitrogen increased to 48mg / L, and the total nitrogen concentration was 220mg / L. At this time, alkali solution was no longer added to control the pH value, and the photohydrolysis reaction continued for 0.5h. The pH of the wastewater gradually decreased to 5.5, and the total cyanide content was still monitored to show 0mg / L. The concentration of residual hydrogen peroxide was 100mg / L, which proved that all the organic nitrile compounds in the water were converted into substances containing -CN, and hydrolyzed into amides or carboxylic acids under alkaline conditions, and the toxicity of the cyanide compounds was eliminated.

[0039] Sulfuric acid or hydrochloric acid is added to the effluent of the photocatalytic reaction pool to adjust the pH value to 3.0, and then the effluent enters the oxidation reactor operating under acidic conditions. The sewage passes through the bottom distribution plate upward through the filter bed filled with COD reduction, and is discharged from the top sump, with a residence time of 40 minutes. A large amount of gas discharged with the water, as well as the residual 100 mg / L hydrogen peroxide, washes the surface of the filler to meet the requirements of micro-aeration. Hydrogen peroxide catalyzes the reaction of metal ions such as Fe and molybdenum with macromolecular organic matter in the water, and provides more ·OH, causing the organic matter to undergo chain breaking and degradation, and COD reduction treatment is carried out. The effluent COD is reduced to 280 mg / L, TOC: 112 mg / L, total nitrogen: 102 mg / L, ammonia nitrogen: 75 mg / L, and the biodegradability is significantly improved, the B / C value is greater than 0.4, the residual hydrogen peroxide is 0 mg / L, and the dissolved oxygen DO is 6.0 mg / L.

[0040] The wastewater from the nitrile removal and cyanide destruction unit 4 and the 110m 3 / h of alkaline glue washing water is mixed and enters the adsorption sedimentation tank 5. The alkaline water reacts with the acidic water discharged from the nitrile removal and cyanide breaking unit 4 to neutralize. The pH value after neutralization is 7.8 and they are collected together in the sludge adsorption sedimentation tank 5. A large number of microorganisms first quickly intercept and adsorb the particulate matter and colloidal matter in the influent, with a retention time of 0.5h. The DO drops rapidly to below 0.1, meeting the influent requirements of the hydrolysis acidification tank 6 (A1 tank). The sewage is hydrolyzed and acidified for 36h, and the MLSS unit mass of activated sludge is 8000mg / L. After hydrolysis and acidification, the COD of the sewage drops to 195mg / L, TOC: 80mg / L, total nitrogen: 102mg / L, ammonia nitrogen: 88mg / L, and nitrate nitrogen: 5mg / L.

[0041] The effluent from the hydrolysis and acidification tank 6 flows by gravity to the denitrification tank 7, where it is fully mixed with the effluent from the aeration tank 8, the circulating water wastewater in the plant area, and the desalted water after adding alkali and removing hardness at the water inlet of the denitrification tank 7. The water volume reaches 240m 3 / h. The water quality is: COD: 125mg / L, TOC: 47mg / L, total nitrogen: 71mg / L, ammonia nitrogen: 51mg / L, nitrate nitrogen: 3mg / L. The sewage enters the denitrification tank 7 (A2 tank) and aeration tank 8 (O tank) in turn for denitrification and COD reduction. In the denitrification tank 7, the pH is controlled at 6.5-7.5, the MLSS is 3500mg / L, the DO<0.5mg / L hydraulic retention time is 12.0h; the pH in the activated sludge aeration tank 8 is controlled at 7.5-8.5, the MLSS is 5000mg / L, the hydraulic retention time is 18h, and the DO>4mg / L. The biochemical effluent of the denitrification tank 7 enters the secondary sedimentation tank 9 for sludge sedimentation to reduce the suspended solids concentration and the total phosphorus content to 0.2mg / L. The COD removal rate in the biochemical treatment stage reached 61.8%, and the effluent quality was: COD: 48 mg / L, TOC: 25 mg / L, total nitrogen: 20 mg / L, ammonia nitrogen: 10 mg / L, nitrate nitrogen: 1.5 mg / L.

[0042] In order to meet higher standards of discharge requirements, the sewage adopts the combined process of "denitrification filter 10 + engineering bacteria biofilter 11 + sedimentation filtration" to further reduce the concentration of TOC, nitrate nitrogen and total nitrogen in the sewage to ensure that the system's external sewage is stable and up to standard. After deep treatment, all sewage in the nitrile rubber production unit area is effectively treated, and the final external sewage COD: 28mg / L, ammonia nitrogen: 1.5mg / L, total nitrogen: 3mg / L, TOC: 11mg / L, total phosphorus is not detected, meeting the GB31571-2015 direct discharge standard.

[0043] The final discharge control indicators of wastewater are COD ≤ 30mg / L, ammonia nitrogen ≤ 2mg / L, total nitrogen ≤ 7mg / L, TOC ≤ 15mg / L, and total phosphorus ≤ 0.5mg / L.

[0044] Example 2 14m from the monomer recovery unit of a nitrile rubber wastewater treatment plant 3 / h of alkaline drainage and 25m3 / h from the condensation unit 3 / h of acidic condensed water, and 5m2 of sewage from accident pool 14 containing high concentrations of acrylonitrile and difficult-to-degrade pollutants 3 / h after mixing, the pH value is adjusted to 6-9, and it enters the homogenization tank 1, where it stays for 12 hours to precipitate and remove some rubber residues and latex particles that are not completely condensed. The COD of the influent of the homogenization tank 1 is 1280 mg / L, TOC: 581 mg / L, total nitrogen: 189 mg / L, and ammonia nitrogen: not detected.

[0045] The effluent of homogenization tank 1 is added with flocculant PAC at a concentration of 150mg / L and coagulant PAM at a concentration of 5mg / L, and enters the two-stage flotation tank 2 including vortex flotation and dissolved air flotation treatment. After the effluent of the two-stage flotation tank 2 is removed from impurities, it flows into the high-density sedimentation tank 3 by gravity, and the suspended impurities and oligomers in the water are further removed, and the turbidity is reduced from 18NTU to below 4NTU. The purpose of improving the transmittance of ultraviolet light is achieved, and at the same time, the rubber oligomers are prevented from adhering to the surface of the lamp tube of the photocatalytic reactor under the action of high temperature. The effluent of high-density sedimentation tank 3 is added with alkali solution in the pipeline for pH adjustment, and the pH is controlled to 12, creating good conditions for the operation of nitrile removal and cyanide breaking unit 4. The effluent of high-density sedimentation tank 3 has COD: 960mg / L, TOC: 355mg / L, total nitrogen: 173mg / L, and ammonia nitrogen: not detected.

[0046] Since the sewage treated by the homogenization tank 1, the two-stage flotation tank 2, the high-density sedimentation tank 3 and the nitrile removal and cyanide breaking unit 4 contains incompletely recovered acrylonitrile gas and other -CN-containing compounds, the tail gas containing acrylonitrile will be volatilized during the stirring and aeration process, which will cause serious harm to the surrounding environment of the factory and the health of the operators. Therefore, in the process described in the patent, the tail gas of the above-mentioned treatment units is centrally collected and sent to the waste gas absorption tower 13 for harmless treatment. In the waste gas absorption tower 13, a 30% sodium sulfite solution is used to absorb and treat the tail gas containing acrylonitrile and cyanide to generate sodium cyanoethyl sulfonate with high solubility and low volatility. The absorption liquid regularly monitors the concentration and pH value of sodium sulfite, and after adsorption saturation, it is collected into the hydrolysis adjustment tank of the nitrile removal and cyanide breaking unit 4 and mixed with 44m 3 / hThe pre-treated sewage is mixed and then treated together for nitrile removal and cyanide breaking to fundamentally eliminate the impact of acrylonitrile.

[0047] The effluent from the high-density sedimentation tank 3 enters the nitrile removal and cyanide breaking treatment, which includes hydrolysis under alkaline conditions and advanced oxidation reactions under acidic conditions. The effluent from the high-density sedimentation tank 3 has sewage COD: 1690mg / L, TOC: 676mg / L, total nitrogen: 343mg / L, and ammonia nitrogen: not detected. Alkali solution is added to adjust the pH value to 10.5, and the concentration of hydrogen peroxide added is 2500mg / L. It enters the hydrolysis adjustment tank for homogenization adjustment with a residence time of 4h. The effluent from the hydrolysis adjustment tank then enters the UV / H2O2 photocatalytic reaction tank to improve the biodegradability of the wastewater. The ultraviolet light-promoted hydrolysis reaction temperature is 55℃, and the cumulative reaction time is 4h. The pH value changes are continuously monitored for 2h after the reaction starts, and alkali solution is added to control the pH to 11.0-12.0, and the content of total cyanide and ammonia nitrogen in the water is monitored. After 2 hours of reaction, the total cyanide monitoring value of the sewage was 5 mg / L, and the residual concentration of H2O2 was 20 mg / L. H2O2 with a concentration of 1000 mg / L was added to the water, and the reaction continued for 1.5 hours. The concentration of ammonia nitrogen was monitored to be 62 mg / L, and the total cyanide concentration was 0 mg / L; at this time, no more alkali solution was added to control the pH value, and the photo-promoted hydrolysis reaction continued for 0.5 hours. The pH of the wastewater gradually dropped to 5, and the concentration of residual hydrogen peroxide in the hydrolysis reaction effluent was 30 mg / L, proving that all the organic nitrile compounds in the water were converted into substances containing -CN, and hydrolyzed into amides or carboxylic acids under alkaline conditions, and the toxicity of cyanide compounds was eliminated.

[0048] Sulfuric acid or hydrochloric acid is added to the effluent of the photocatalytic reaction pool to adjust the pH value to about 2.5, and then enters the oxidation reactor operating under acidic conditions. The sewage passes through the bottom distribution plate upward through the filter bed filled with COD reduction, and is discharged from the top sump, with a residence time of 60 minutes. A large amount of gas discharged with the water, as well as the residual 30mg / L hydrogen peroxide, flushes the surface of the filler to meet the requirements of micro-aeration. Hydrogen peroxide catalyzes the reaction of metal ions such as Fe and molybdenum with macromolecular organic matter in the water, and provides more ·OH, causing chain scission and degradation of organic matter, reducing the COD of sewage. The effluent COD is reduced to 422mg / L, TOC: 192mg / L, total nitrogen: 213mg / L, ammonia nitrogen: 89mg / L, biodegradability is significantly improved, B / C value is greater than 0.4, the residual amount of hydrogen peroxide is 0mg / L, and the dissolved oxygen DO is 5.0mg / L.

[0049] The wastewater from the nitrile removal and cyanide destruction unit 4 and the 120m 3 / h of alkaline glue washing water is mixed and enters the adsorption sedimentation tank 5. The alkaline water reacts with the acidic water discharged from the nitrile removal and cyanide breaking unit 4 to neutralize, and the pH value is 9.0, and they are collected together in the sludge adsorption sedimentation tank 5. A large number of microorganisms first quickly intercept and adsorb the particulate matter and colloidal matter in the influent, with a retention time of 40min. The DO drops rapidly to below 0.1, meeting the influent requirements of the hydrolysis acidification tank 6 (A1 tank). The sewage is hydrolyzed and acidified for 48h, MLSS: 8000mg / L, and the COD of the sewage after hydrolysis and acidification drops to 289mg / L, TOC: 108mg / L, total nitrogen: 198mg / L, ammonia nitrogen: 133mg / L, and nitrate nitrogen: 15mg / L.

[0050] The effluent from the hydrolysis and acidification tank 6 flows by gravity to the denitrification tank 7, where it is fully mixed with the effluent from the aeration tank 8, the circulating water wastewater in the plant area, and the desalted water after adding alkali and removing hardness at the water inlet of the denitrification tank 7. The water volume reaches 260m 3 / h. The water quality is: COD: 194mg / L, TOC: 70mg / L, total nitrogen: 135mg / L, ammonia nitrogen: 84mg / L, nitrate nitrogen: 9mg / L. The sewage enters the denitrification tank 7 (A2 tank) and the aeration tank (8O tank) in turn for denitrification and COD reduction. In the denitrification tank 7, the pH is controlled at 6.5-7.5, the MLSS is 3500mg / L, the DO<0.2mg / L hydraulic retention time is 15.0h; the pH in the activated sludge aeration tank 8 is controlled at 7.5-8.5, the MLSS is 6000mg / L, the hydraulic retention time is 22h, and the DO>4mg / L. The biochemical effluent enters the secondary sedimentation tank 9 for sludge sedimentation to reduce the suspended solids concentration, and the total phosphorus concentration is 0.3mg / L. The COD removal rate in the biochemical treatment stage reached 71.6%, and the effluent quality was: COD: 55 mg / L, TOC: 20 mg / L, total nitrogen: 25 mg / L, ammonia nitrogen: 10 mg / L, nitrate nitrogen: 2.2 mg / L.

[0051] In order to meet higher standards of discharge requirements, the sewage adopts the combined process of "denitrification filter 10 + engineering bacteria biofilter 11 + sedimentation filtration" to further reduce the TOC, nitrate nitrogen and total nitrogen concentrations in the sewage to ensure that the system's external sewage is stable and up to standard. After deep treatment, all sewage in the nitrile rubber production unit area is effectively treated, and the final external sewage COD: 29mg / L, TOC: 13mg / L, ammonia nitrogen: 1.8mg / L, total nitrogen: 6mg / L, total phosphorus is not detected, meeting the GB31571-2015 direct discharge standard.

[0052] The final discharge control indicators of wastewater are COD ≤ 30mg / L, ammonia nitrogen ≤ 2mg / L, total nitrogen ≤ 7mg / L, TOC ≤ 15mg / L, and total phosphorus ≤ 0.5mg / L.

[0053] Example 3 12m from the monomer recovery unit of a nitrile rubber wastewater treatment plant 3 / h of alkaline drainage and 20m3 / h from the condensation unit 3 / h of acidic condensation water, adjusted to pH 6-9, and then entered homogenization tank 1, where it stayed for 12 hours to precipitate and remove some rubber residues and incompletely condensed latex particles. Homogenization tank 1 inlet water COD: 951mg / L, TOC: 346mg / L, total nitrogen: 92mg / L, ammonia nitrogen: not detected.

[0054] The effluent of homogenization tank 1 is added with flocculant PAC at a concentration of 100 mg / L and coagulant PAM at a concentration of 2.5 mg / L, and enters the two-stage flotation tank 2 including vortex flotation and dissolved air flotation. After the impurities are removed from the effluent of the two-stage flotation tank 2, it flows into the high-density sedimentation tank 3 by gravity, and the suspended impurities and oligomers in the water are further removed. The turbidity is reduced from 11NTU to below 2NTU, achieving the purpose of improving the transmittance of ultraviolet light, and at the same time avoiding the adhesion of rubber oligomers to the surface of the lamp tube of the photocatalytic reactor under the action of high temperature. Alkali solution is added to the effluent of high-density sedimentation tank 3 in the pipeline for pH adjustment, and the pH is controlled to 11.0, creating good conditions for the operation of nitrile removal and cyanide breaking unit 4. COD of the effluent of high-density sedimentation tank 3: 518 mg / L, TOC: 195 mg / L, total nitrogen: 145 mg / L, ammonia nitrogen: not detected.

[0055] Since the wastewater treated by the homogenization tank 1, the two-stage flotation tank 2, the high-density sedimentation tank 3 and the nitrile removal and cyanide breaking unit 4 contains incompletely recovered acrylonitrile gas and other -CN-containing compounds, the tail gas containing acrylonitrile will be volatilized during the stirring and aeration process, which will cause serious harm to the surrounding environment of the factory and the health of the operators. Therefore, in the process described in the patent, the tail gas of the above-mentioned treatment units is centrally collected and sent to the waste gas absorption tower 13 for harmless treatment. In the waste gas absorption tower 13, a 15% sodium sulfite solution is used to absorb and treat the tail gas containing acrylonitrile and cyanide to generate sodium cyanoethyl sulfonate with high solubility and low volatility. The absorption liquid regularly monitors the concentration and pH value of sodium sulfite, and after adsorption saturation, it is collected into the hydrolysis adjustment tank of the nitrile removal and cyanide breaking unit 4 and mixed with 32m 3 / hThe pre-treated sewage is mixed and then treated together for nitrile removal and cyanide breaking to fundamentally eliminate the impact of acrylonitrile.

[0056] The effluent from the high-density sedimentation tank 3 enters the nitrile removal and cyanide breaking treatment, which includes hydrolysis under alkaline conditions and advanced oxidation reactions under acidic conditions. The effluent from the high-density sedimentation tank 3 has a COD of 1370 mg / L, a TOC of 527 mg / L, a total nitrogen of 326 mg / L, and ammonia nitrogen that is not detected. Alkali solution is added to adjust the pH value to 11, and the concentration of hydrogen peroxide added is 1800 mg / L. It enters the hydrolysis adjustment tank for homogenization adjustment with a residence time of 3 hours. The effluent from the hydrolysis adjustment tank then enters the UV / H2O2 photocatalytic reaction tank to improve the biodegradability of the wastewater. The ultraviolet light-promoted hydrolysis reaction temperature is 60°C and the reaction time is 3.5 hours. Monitor the changes in pH value in the first 3 hours after the reaction starts, and continuously add alkali solution to control the pH to 11.0-11.5. The total cyanide and ammonia nitrogen contents in the water were monitored. When the total cyanide monitoring value of the sewage showed 0, the concentration of ammonia nitrogen increased to 68 mg / L, and the total nitrogen concentration was 150 mg / L. At this time, no alkali solution was added to control the pH value. The photohydrolysis reaction continued for 0.5 h, and the pH of the wastewater gradually decreased to 5.8. The monitoring of the total cyanide content still showed 0 mg / L, and the concentration of residual hydrogen peroxide was 150 mg / L, proving that all the organic nitrile compounds in the water were converted into substances containing -CN, and hydrolyzed into amides or carboxylic acids under alkaline conditions, and the toxicity of the cyanide compounds was eliminated.

[0057] Sulfuric acid or hydrochloric acid is added to the effluent of the photocatalytic reaction pool to adjust the pH value to 3.5, and then enter the oxidation reactor operating under acidic conditions. The sewage passes through the bottom distribution plate upward through the filter bed filled with COD reduction, and is discharged from the top sump, with a residence time of 30 minutes. A large amount of gas discharged with the water, as well as the residual 150mg / L hydrogen peroxide, flushes the surface of the filler to meet the requirements of micro-aeration. Hydrogen peroxide catalyzes the reaction of metal ions such as Fe and molybdenum with macromolecular organic matter in the water, and provides more ·OH, causing the organic matter to undergo chain breaking and degradation, and COD reduction treatment is carried out. The effluent COD is reduced to 368mg / L, TOC: 160mg / L, total nitrogen: 116mg / L, ammonia nitrogen: 85mg / L, biodegradability is significantly improved, B / C value is greater than 0.4, the residual amount of hydrogen peroxide is 0mg / L, and the dissolved oxygen DO is 5.5mg / L.

[0058] The wastewater from the nitrile removal and cyanide destruction unit 4 and the 110m 3 / h of alkaline glue washing water is mixed and enters the adsorption sedimentation tank 5. The alkaline water reacts with the acidic water discharged from the nitrile removal and cyanide breaking unit 4 to neutralize, and the pH value is 7.8, and they are collected together in the sludge adsorption sedimentation tank 5. A large number of microorganisms first quickly intercept and adsorb the particulate matter and colloidal matter in the influent. When staying for 40 minutes, the DO drops rapidly to below 0.1, meeting the influent requirements of the hydrolysis acidification tank 6 (A1 tank). The sewage is hydrolyzed and acidified for 24 hours, MLSS: 8000mg / L, and the COD of the sewage after hydrolysis and acidification drops to 322mg / L, TOC: 129mg / L, total nitrogen: 103mg / L, ammonia nitrogen: 59mg / L, nitrate nitrogen: 4mg / L.

[0059] The effluent from the hydrolysis and acidification tank 6 flows by gravity to the denitrification tank 7, where it is fully mixed with the effluent from the aeration tank 8, the circulating water wastewater in the plant area, and the desalted water after adding alkali to remove hardness at the water inlet of the denitrification tank 7. The water volume reaches 235m 3 / h. The water quality is: 132mg / L, TOC: 48mg / L, total nitrogen: 73mg / L, ammonia nitrogen: 30mg / L, nitrate nitrogen: 4mg / L. The sewage enters the denitrification tank 7 (A2 tank) and aeration tank 8 (O tank) in turn for denitrification and COD reduction. In the denitrification tank 7, the pH is controlled at 6.5-7.5, the MLSS is 3500mg / L, the DO<0.5mg / L hydraulic retention time is 12.0h; the pH in the activated sludge aeration tank 8 is controlled at 7.5-8.5, the MLSS is 5000mg / L, the hydraulic retention time is 18h, and the DO>4mg / L. The biochemical effluent enters the secondary sedimentation tank 9 for sludge sedimentation to reduce the suspended solids concentration, and the total phosphorus concentration is 0.1mg / L. The COD removal rate in the biochemical treatment stage reached 67%, and the effluent quality was: COD: 43 mg / L, TOC: 15 mg / L, total nitrogen: 22 mg / L, ammonia nitrogen: 11 mg / L, nitrate nitrogen: 2.5 mg / L.

[0060] In order to meet higher standards of discharge requirements, the sewage adopts the combined process of "denitrification filter 10 + engineering bacteria biofilter 11 + sedimentation filtration" to further reduce the TOC, nitrate nitrogen and total nitrogen concentrations in the sewage to ensure that the system's external sewage is stable and up to standard. After deep treatment, all sewage in the nitrile rubber production unit area is effectively treated, and the final external sewage COD: 28mg / L, TOC: 12mg / L, ammonia nitrogen: 1.3 mg / L, total nitrogen: 6mg / L, total phosphorus is not detected, meeting the GB31571-2015 direct discharge standard.

Claims

1. A wastewater treatment device for nitrile rubber production, characterized in that: It comprises a homogenization tank (1), a two-stage flotation tank (2), a high-density sedimentation tank (3), a nitrile removal and cyanide destruction unit (4), an adsorption sedimentation tank (5), a hydrolysis acidification tank (6), a denitrification tank (7), an aeration tank (8), a secondary sedimentation tank (9), a denitrification filter tank (10), an engineered bacteria biofilter tank (11) and a sedimentation filter tank (12) which are sequentially connected through pipelines; The homogenization tank (1) is provided with a monomer recovery unit drainage water inlet pipeline (15) and a condensation unit acid water inlet pipeline (16); A flocculant inlet pipe (17) is provided on the pipeline between the homogenization tank (1) and the two-stage air flotation tank (2), an alkali inlet pipe (18) is provided on the pipeline between the two-stage air flotation tank (2) and the high-density sedimentation tank (3), and a coagulation unit alkaline water inlet pipe (19) is provided on the pipeline between the nitrile removal and cyanide breaking unit (4) and the adsorption sedimentation tank (5); A nitrification liquid return pipeline (20) is also provided between the aeration tank (8) and the denitrification tank (7); a sludge return pipeline (21) is also provided between the secondary sedimentation tank (9) and the adsorption sedimentation tank (5); The pipeline between the hydrolysis acidification tank (6) and the denitrification tank (7) is also connected to a high-density sedimentation tank 2 (25) and a circulating water sewage inlet pipeline (22). The high-density sedimentation tank 2 (25) is provided with a desalted water concentrated water inlet pipeline (23) and an alkali inlet pipeline 2 (24).

2. The nitrile rubber production wastewater treatment device according to claim 1, characterized in that: The homogenization tank (1) is also connected to an accident tank (14).

3. The nitrile rubber production wastewater treatment device as claimed in claim 2, characterized in that: The homogenization tank (1), the accident tank (14), the two-stage flotation tank (2), the first high-density sedimentation tank (3) and the nitrile removal and cyanide breaking unit (4) are all connected to the waste gas absorption tower (13) through pipelines; an absorption liquid recycling pipeline (26) is also provided between the waste gas absorption tower (13) and the nitrile removal and cyanide breaking unit (4).

4. The nitrile rubber production wastewater treatment device as claimed in claim 3, characterized in that: The nitrile removal and cyanide destruction unit (4) is provided with a hydrolysis adjustment tank, a photocatalytic reaction tank and an oxidation reactor.

5. The process for treating wastewater produced by nitrile rubber by a treatment device as claimed in claim 4, characterized in that: The following steps are involved: 1) Pretreatment of rubber-containing wastewater: The alkaline wastewater discharged from the acrylonitrile monomer recovery unit and the acidic water from the coagulation unit are mixed and then enter the homogenization tank (1), the pH value is adjusted to neutral to alkaline, flocculants and coagulants are added, and then enter the two-stage flotation tank. The effluent from the two-stage flotation tank enters the high-density sedimentation tank (3) to remove suspended impurities and oligomers in the water. Alkali solution is added to the effluent from the high-density sedimentation tank (3) to adjust the pH; 2) Nitrile removal and cyanide destruction treatment: including hydrolysis under alkaline conditions and advanced oxidation reaction under acidic conditions. The effluent from the high-density sedimentation tank (3) is treated with alkali to adjust the pH value, and hydrogen peroxide is added. The effluent enters the hydrolysis adjustment tank for homogenization adjustment, and then enters the photocatalytic reaction tank for hydrolysis reaction. During the reaction, the total cyanide content, ammonia nitrogen concentration and hydrogen peroxide residue are monitored in real time. When the total cyanide monitoring value of the sewage shows 0 and the ammonia nitrogen concentration rises significantly, alkali is no longer added to control the pH value. As the reaction proceeds, the pH value of the wastewater drops to neutral to slightly acidic, and the sewage enters the oxidation reactor under acidic conditions for advanced oxidation reaction; 3) Biochemical treatment: The alkaline water discharged from the condensation unit is mixed with the acidic water discharged after the nitrile and cyanide removal treatment, and a neutralization reaction occurs. The water is then collected together in the adsorption sedimentation tank (5) for adsorption and sedimentation. The water enters the hydrolysis and acidification tank (6) to degrade the macromolecular organic matter in the sewage into micromolecular organic matter. The effluent from the hydrolysis and acidification tank (6) flows by gravity to the denitrification tank (7). The effluent return liquid from the subsequent aeration tank (8), the circulating water from the plant area, and the desalted water after adding alkali to remove hardness are fully mixed at the water inlet of the denitrification tank (7) to remove the total nitrogen in the sewage. The effluent from the denitrification tank (7) enters the aeration tank (8) for carbonization and nitrification reactions to remove COD in the sewage and convert ammonia nitrogen into nitrate and nitrite. The water is then precipitated in the secondary sedimentation tank (9). 4) Deep treatment of sewage to meet standards: The sewage that has been precipitated in the secondary sedimentation tank (9) enters the denitrification filter (10), the engineered bacteria biofilter (11) and the sedimentation filter (12) in sequence to further reduce the concentrations of total organic carbon, nitrate nitrogen and total nitrogen in the sewage, so as to ensure that the sewage discharged from the system meets the standards stably.

6. The process for treating wastewater from nitrile rubber production as claimed in claim 5, wherein: In step 1), the neutral to alkaline pH range is 6-9, and alkali solution is added to the effluent of the high-density sedimentation tank 1 (3) to adjust the pH to 10-12.5, preferably 10.5-12.

7. The process for treating wastewater from nitrile rubber production as claimed in claim 5, wherein: In step 2), alkali is added to adjust the pH to 10.5, the pH of the photocatalytic reaction tank for hydrolysis reaction is > 10.5, the reaction temperature is 40-60°C, preferably 45-55°C, the reaction time is 2-5h, preferably 2.5-4.5h, the neutral to slightly acidic pH range in step 2) is 4.5-6.5, and the concentration of hydrogen peroxide added is 1500-2500mg / L.

8. The process for treating wastewater from nitrile rubber production as claimed in claim 5, wherein: The pH of the neutralization reaction in step 3) is 6-9, the residence time in the adsorption sedimentation tank (5) is 0.5-1 h, and the residence time in the hydrolysis acidification tank (6) is 20-48 h, preferably 24-45 h.

9. The process for treating wastewater from nitrile rubber production as claimed in claim 5, wherein: The method also includes collecting and treating nitrile-containing tail gas, specifically: the acrylonitrile-containing tail gas volatilized in the homogenizing tank (1), the two-stage flotation tank (2), the first high-density sedimentation tank (3), the nitrile removal and cyanide breaking unit (4) and the accident tank (14) enters the waste gas absorption tower (13) for treatment; and the absorption liquid in the waste gas absorption tower (13) flows back into the nitrile removal and cyanide breaking unit (4).

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