Method for treating liquid nitrile rubber wastewater

Abstract

The invention discloses a liquid nitrile rubber wastewater treatment method, which comprises: S1, carrying out supergravity air stripping on nitrile rubber wastewater under nitrogen protection under the conditions of a supergravity factor of 50-100 and a gas-liquid ratio of 500-2500; s2, sequentially carrying out ozone oxidation and Fenton oxidation on the wastewater treated in the step S1; and S3, carrying out solid-liquid separation on the wastewater treated in the step S2 to obtain a liquid component, distilling the liquid component, and adjusting the pH value until the wastewater reaches the discharge standard. After the high-concentration liquid nitrile rubber wastewater with the COD of 5000-20000 mg / L is treated, the COD is reduced to 50 mg / L or below, impact on a subsequent sewage treatment plant is avoided, and up-to-standard discharge of the wastewater is realized.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment technology, and specifically relates to a method for treating liquid nitrile rubber wastewater. Background Technology

[0002] Liquid rubber, an important type of synthetic rubber, typically has a number-average molecular weight of 500–10,000 and is a viscous polymer with free flow at room temperature. There are many types of liquid rubber, mainly including liquid nitrile rubber (NBR) and liquid styrene-butadiene rubber (SBR). Liquid NBR is polymerized from butadiene and acrylonitrile, two main monomers, with the addition of initiators, activators, regulators, and dispersants. Due to the addition of various additives during its production, the wastewater contains a wide variety of pollutants, high concentrations of organic matter, and low biodegradability, making it difficult to treat and recognized as recalcitrant organic wastewater. For liquid NBR wastewater with a COD of 5000–20000 mg / L, untreated wastewater will have a significant impact on subsequent wastewater treatment systems. Therefore, how to treat this type of liquid NBR wastewater simply, quickly, with low cost, and efficiently has become a focus of attention.

[0003] Industrial wastewater treatment methods include physical, chemical, biological, and combined methods. Physical methods include incineration, distillation, adsorption, and membrane separation; chemical methods include chemical coagulation, wet oxidation, Fenton oxidation, ozone oxidation, and supercritical water oxidation; and biological methods include activated sludge processes, membrane bioreactors, hydrolysis acidification, and biofilters. Currently, nitrile rubber wastewater treatment mainly employs a combination of pretreatment and biochemical treatment. While this method can remove pollutants, it is ineffective for wastewater containing recalcitrant additives and with a COD of 5000–20000 mg / L, affecting compliance with discharge standards. Therefore, there is an urgent need to develop a highly efficient method for treating liquid nitrile rubber wastewater.

[0004] Chinese patent CN101723526B discloses a membrane treatment method for synthetic rubber production wastewater. This method employs a treatment process of "catalytic oxidation + coagulation sedimentation + ultrafiltration + reverse osmosis." First, hydrogen peroxide is used as the oxidant and ferrous sulfate as the catalyst to catalytically oxidize the wastewater, primarily removing recalcitrant COD. Then, coagulation sedimentation removes iron and suspended solids, followed by ultrafiltration to remove colloids and residual particulate matter. Finally, reverse osmosis is used for desalination. Because the pretreatment effectively removes organic matter that significantly impacts membrane system operation, this method produces excellent effluent quality. However, direct oxidation is difficult to effectively reduce COD in liquid nitrile rubber wastewater containing recalcitrant additives. Furthermore, this wastewater is prone to membrane fouling and clogging; therefore, this method is not suitable for treating liquid nitrile rubber wastewater.

[0005] Chinese patent CN103787538B discloses a method for recycling and treating nitrile rubber wastewater. The method involves distilling the wastewater to remove most of the acrylonitrile; then contacting the wastewater with ozone and / or hydrogen peroxide to oxidize and decompose the remaining acrylonitrile. This invention effectively reduces the acrylonitrile content in nitrile rubber wastewater through distillation and oxidation. However, for liquid nitrile rubber wastewater containing a variety of organic compounds, high COD, and recalcitrant additives, direct distillation poses safety risks due to the large amount of volatile organic compounds. Furthermore, the high COD content makes direct distillation energy-intensive. Therefore, this method is not suitable for treating such liquid nitrile rubber wastewater.

[0006] Chinese patent CN105461156B discloses a method for treating wastewater from nitrile rubber (NBR) production. The method involves adjusting the pH of the wastewater to above 7, and then mixing the pH-adjusted wastewater with borohydride and aluminum chloride to reduce acrylonitrile in the wastewater. The wastewater after acrylonitrile reduction is then subjected to coagulation-flotation treatment, hydrolysis-acidification treatment, activated sludge treatment, and aerated biological filter purification treatment. This invention can effectively remove acrylonitrile from wastewater; however, its effectiveness in removing COD from liquid NBR wastewater containing recalcitrant additives is limited.

[0007] Chinese patent CN104710077B discloses a synthetic rubber wastewater treatment system, including a PLC system, an equalization tank, a neutralization tank, an air flotation tank, a biological contact oxidation tank, a loaded Fenton oxidation tank, an aerobic MBR tank, an ozone catalytic oxidation tower, and a breakpoint chlorination and denitrification tank. The sludge treatment system includes a sludge storage tank, a sludge thickening tank, and a plate and frame filter press. The outlet of the breakpoint chlorination and denitrification tank is connected to a flowing carbon filter tower via a water pump, which further treats organic matter and ammonia nitrogen in the wastewater that does not meet standards. This invention can effectively remove recalcitrant organic matter and high levels of ammonia nitrogen from water. However, the technical route of this invention is complex and not conducive to operation. Furthermore, the method has limited COD removal efficiency for liquid nitrile rubber wastewater containing recalcitrant additives.

[0008] The large volume of liquid nitrile rubber wastewater discharged externally, its high volatility, and high COD content increase the operating load of wastewater treatment plants. Given the limitations of existing technologies, how to degrade organic matter in liquid nitrile rubber wastewater is an urgent problem to be solved. Summary of the Invention

[0009] The purpose of this invention is to provide a method for treating liquid nitrile rubber wastewater, so as to solve the problem that it is difficult to treat nitrile rubber wastewater with high COD content in the prior art.

[0010] To achieve the above objectives, the present invention provides a method for treating liquid nitrile rubber wastewater, comprising the following steps:

[0011] S1, Nitrile rubber wastewater was subjected to hypergravity stripping under nitrogen protection. The hypergravity stripping conditions were: hypergravity factor 50-100, gas-liquid ratio 500-2500.

[0012] S2, the wastewater treated in step S1 is then subjected to ozone oxidation and Fenton oxidation in sequence;

[0013] S3. The wastewater treated in step S2 is subjected to solid-liquid separation to obtain liquid components. The liquid components are then distilled and the pH is adjusted to meet the discharge standards.

[0014] The method for treating liquid nitrile rubber wastewater according to the present invention further includes a step of gas separation of the gas after gravity stripping in step S1. This step enables the concentration, separation, resource utilization, and nitrogen recycling of acrylonitrile monomers.

[0015] The method for treating liquid nitrile rubber wastewater according to the present invention uses a gas separation membrane for gas separation, wherein the gas separation membrane is one or more of inorganic membranes and / or organic membranes.

[0016] The ozone oxidation conditions for the treatment of liquid nitrile rubber wastewater described in this invention are as follows: the ratio of ozone dosage to COD of the stripped wastewater is 0.5 to 1, and the reaction time is 30 to 60 minutes.

[0017] The method for treating liquid nitrile rubber wastewater according to the present invention uses the following Fenton oxidation conditions: the ratio of hydrogen peroxide dosage to COD mass of the wastewater after ozone oxidation treatment is 0.1–3, and the concentrations of hydrogen peroxide and Fe... 2+ The molar ratio is 1:1 to 5:1, the reaction time is 30 to 60 min, and the reaction temperature is 40 to 65℃.

[0018] This invention does not particularly limit the solid-liquid separation method, such as, but not limited to, centrifugation, pressure filtration, or natural sedimentation, and the separated sludge is discharged from the system after dewatering.

[0019] In the treatment method for liquid nitrile rubber wastewater of the present invention, the distillation method in step S3 is atmospheric distillation or vacuum distillation.

[0020] The method for treating liquid nitrile rubber wastewater according to the present invention wherein the temperature at the top of the atmospheric distillation tower is not greater than 95°C, the temperature at the bottom of the tower is not less than 120°C, and the residence time is 30-90 min.

[0021] The method for treating liquid nitrile rubber wastewater according to the present invention includes a vacuum distillation pressure of 0.08–0.095 MPa, a temperature of 40–80 °C, and a residence time of 10–60 min.

[0022] The method for treating liquid nitrile rubber wastewater according to the present invention has a COD of 5000-20000 mg / L.

[0023] The method for treating liquid nitrile rubber wastewater of the present invention involves the waste gas generated during the entire process being treated uniformly by entering a waste gas collection pipeline network or a waste gas treatment unit, and the solid waste generated being uniformly dehydrated and transported off-site for treatment.

[0024] The beneficial effects of this invention are:

[0025] This invention reduces the COD of high-concentration liquid nitrile rubber wastewater with a COD of 5000-20000 mg / L to below 50 mg / L, avoiding the impact on subsequent wastewater treatment plants and achieving wastewater discharge that meets standards.

[0026] This invention utilizes a high-gravity stripping method. Due to the higher gas-liquid mass transfer efficiency of high gravity, wastewater and nitrogen can fully contact each other, allowing volatile organic compounds (VOCs) in the wastewater to be stripped away. This improves stripping efficiency and removes most of the VOCs (acrylonitrile) from the wastewater more effectively, significantly reducing COD, decreasing the load on subsequent treatment processes, and lowering energy consumption. Furthermore, because the stripping is carried out at room temperature under nitrogen protection, it avoids the large-scale overflow of VOCs from the wastewater that occurs during high-temperature distillation, eliminating the safety hazard of explosion.

[0027] This invention concentrates and separates acrylonitrile, nitrogen, and other small amounts of waste gas through gas separation. The separated acrylonitrile is recycled as a raw material to the liquid nitrile rubber production unit, realizing waste utilization. The nitrogen enters the stripping unit for recycling, reducing operating costs.

[0028] This invention removes most of the volatile and degradable organic matter from liquid nitrile rubber wastewater through supergravity stripping, ozone oxidation, and Fenton oxidation units, significantly reducing the organic matter content in the wastewater. Furthermore, the heat consumption of the distillation unit is greatly reduced during subsequent distillation, saving on treatment costs.

[0029] This invention utilizes ozone oxidation to both oxidize and degrade wastewater, while simultaneously blowing out some volatile components from the system. Ozone plays a dual role, accelerating the removal rate of COD from wastewater and reducing ozone consumption. Furthermore, after the ozone oxidation reaction, the wastewater pH decreases to 2-4, eliminating the need for pH adjustment in the Fenton oxidation unit. This reduces operational steps and the need for reagent addition, thus saving on treatment costs.

[0030] This invention enables the deep degradation of organic matter in wastewater using a Fenton oxidation unit. The Fenton oxidation requires heating to 40–60°C, and the treated wastewater directly enters the distillation unit. The heat from the Fenton oxidation unit is reused, reducing the heat consumption of the distillation unit and lowering the treatment cost. Attached Figure Description

[0031] Figure 1 This is a process flow diagram of a method for treating liquid nitrile rubber wastewater according to the present invention. Detailed Implementation

[0032] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0033] Source of raw materials or equipment: The liquid nitrile rubber wastewater comes from a rubber plant of China National Petroleum Corporation.

[0034] Evaluation and analysis methods: COD was determined according to GB11914-1989 (potassium dichromate method).

[0035] Example 1

[0036] Liquid nitrile rubber wastewater with a pH of 9.37 and a COD of 5940 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 1000 and a high-gravity factor of 60, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.5 and a reaction time of 30 minutes, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.64, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 0.5, and the hydrogen peroxide and Fe... 2+ The molar ratio was 1:1, the reaction time was 30 min, and the reaction temperature was 40℃. After the reaction, solid-liquid separation was performed by pressure filtration. The separated sludge, along with other system sludge, was dehydrated and transported for external treatment. The filtrate obtained from solid-liquid separation entered the distillation unit, where atmospheric distillation was performed at a top temperature of 80℃ and a bottom temperature of 125℃ for 30 min. After distillation, the pH of the wastewater was adjusted to 6, and the COD of the resulting wastewater was 32 mg / L.

[0037] Example 2

[0038] Liquid nitrile rubber wastewater with a pH of 9.37 and a COD of 5940 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 1500 and a high-gravity factor of 70, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.8 and a reaction time of 30 min, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.57, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 1, and the hydrogen peroxide and Fe... 2+ The molar ratio was 1:1, the reaction time was 60 min, and the reaction temperature was 50℃. After the reaction, solid-liquid separation was performed by pressure filtration. The separated sludge, along with other system sludge, was dehydrated and transported for external treatment. The filtrate obtained from solid-liquid separation entered the distillation unit, where atmospheric distillation was performed at a top temperature of 85℃ and a bottom temperature of 130℃ for 40 min. After distillation, the pH of the wastewater was adjusted to 7, and the COD of the resulting wastewater was 18 mg / L.

[0039] Example 3

[0040] Liquid nitrile rubber wastewater with a pH of 9.62 and a COD of 9820 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 2000 and a high-gravity factor of 80, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 1, and a reaction time of 60 min. Under the dual effects of stripping and oxidation, the organic matter in the wastewater was further degraded. At the end of the reaction, the wastewater pH was 2.81, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 2, and the hydrogen peroxide and Fe... 2+ The molar ratio was 3:1, the reaction time was 60 min, and the reaction temperature was 50℃. After the reaction, solid-liquid separation was performed by centrifugation. The separated sludge, along with other system sludge, was dehydrated and transported for external treatment. The filtrate obtained from the solid-liquid separation entered the distillation unit, where atmospheric distillation was performed at a top temperature of 80℃ and a bottom temperature of 125℃ for 30 min. After distillation, the pH of the wastewater was adjusted to 6, and the COD of the resulting wastewater was 25 mg / L.

[0041] Example 4

[0042] Liquid nitrile rubber wastewater with a pH of 9.62 and a COD of 9820 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 1500 and a high-gravity factor of 70, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.5 and a reaction time of 30 min, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.95, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 3, and the hydrogen peroxide and Fe... 2+ The molar ratio was 5:1, the reaction time was 30 min, and the reaction temperature was 60℃. After the reaction, solid-liquid separation was performed by pressure filtration. The separated sludge, along with other system sludge, was dehydrated and transported for external treatment. The filtrate obtained from solid-liquid separation entered the distillation unit, where atmospheric distillation was performed at a top temperature of 90℃ and a bottom temperature of 140℃ for 60 min. After distillation, the pH of the wastewater was adjusted to 8, and the COD of the resulting wastewater was 21 mg / L.

[0043] Example 5

[0044] Liquid nitrile rubber wastewater with a pH of 8.94 and a COD of 13650 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 1500 and a high-gravity factor of 60, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 1, and a reaction time of 30 min. Under the dual effects of stripping and oxidation, the organic matter in the wastewater was further degraded. At the end of the reaction, the wastewater pH was 2.48, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 2, and the hydrogen peroxide and Fe... 2+ The molar ratio was 4:1, the reaction time was 40 min, and the reaction temperature was 40℃. After the reaction, solid-liquid separation was performed by natural sedimentation. The separated sludge and other system sludge were dewatered and transported for off-site treatment. The filtrate obtained from solid-liquid separation entered the distillation unit and underwent vacuum distillation at a pressure of 0.9 MPa and a temperature of 60℃ for 10 min. After distillation, the pH of the wastewater was adjusted to 8, and the COD of the resulting wastewater was 35 mg / L.

[0045] Example 6

[0046] Liquid nitrile rubber wastewater with a pH of 8.94 and a COD of 13650 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 2000 and a high-gravity factor of 80, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.8 and a reaction time of 40 min, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.52, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 3, and the hydrogen peroxide and Fe... 2+ The molar ratio was 5:1, the reaction time was 50 min, and the reaction temperature was 50℃. After the reaction, solid-liquid separation was performed by natural sedimentation. The separated sludge and other system sludge were dewatered and transported for off-site treatment. The filtrate obtained from solid-liquid separation entered the distillation unit and underwent vacuum distillation at a pressure of 0.95 MPa and a temperature of 70℃ for 30 min. After distillation, the pH of the wastewater was adjusted to 8, and the COD of the resulting wastewater was 27 mg / L.

[0047] Comparative Example 1

[0048] Liquid nitrile rubber wastewater with a pH of 9.37 and a COD of 5940 mg / L was collected. Sodium borohydride and aluminum chloride were added to the wastewater at concentrations of 2.50 g / L and 50 mg / L, respectively, with a reaction time of 60 min. The wastewater then entered a coagulation and flotation unit, where polyacrylamide was added at a concentration of 2.0 mg / L, with a residence time of 40 min and a surface hydraulic loading of 4 m³. 3 / (m2·h); Wastewater enters the hydrolysis acidification unit, where dissolved oxygen is controlled at 0.1 mg / L and hydraulic retention time is 4 h; the above effluent enters the activated sludge treatment unit, where the activated sludge concentration is 6000 mg / L, dissolved oxygen is 4 mg / L, and retention time is 8 h; wastewater enters the aerated biological filter, where dissolved oxygen is 3 mg / L and volumetric loading is 0.20 kg COD / m 3 The measured COD of the water was 2260 mg / L.

[0049] Comparative Example 2

[0050] Liquid nitrile rubber wastewater with a pH of 9.62 and a COD of 9820 mg / L was collected. The wastewater underwent catalytic oxidation treatment at a reaction temperature of 25℃ and a reaction pressure of atmospheric pressure. 27.5% hydrogen peroxide and ferrous sulfate were added to the wastewater, with the weight ratio of H2O2 to TOC in the wastewater being 5.0. 2+The catalytic oxidation process, with a weight ratio of 0.8 to H₂O₂, involves aeration and mixing, with a reaction residence time of 120 min. The effluent from this process is pressurized and fed into a coagulation unit. The pH is adjusted to 10.0 with 15% NaOH. The wastewater then enters a coagulation tank, where a baffle plate mixing method is used. After a 10-min residence time, the wastewater proceeds to a sedimentation tank for sludge-water separation. The sedimentation tank effluent passes through a multi-media filter at a filtration rate of 7 m / s. The multi-media filter effluent is then coarsely adjusted to pH 9.5 with hydrochloric acid, and 3 mg / L of sodium hypochlorite is added. It then passes through a bag filter before entering the ultrafiltration and reverse osmosis systems. The measured COD of the effluent is 4590 mg / L.

[0051] Comparative Example 3

[0052] Liquid nitrile rubber wastewater with a pH of 8.94 and a COD of 13650 mg / L was collected. The wastewater was subjected to vacuum distillation using a water bath at a pressure of 0.095 MPa and a temperature of 60°C. Immediately after the start of distillation, a large amount of foam was generated, filling the distillation apparatus, posing a safety risk, and the reaction was not continued.

[0053] Comparative Example 4

[0054] Liquid nitrile rubber wastewater with a pH of 9.37 and a COD of 5940 mg / L was collected. The wastewater quality and quantity were adjusted in an equalization tank to ensure uniformity. The effluent from the equalization tank entered a neutralization tank, where the pH was adjusted to 6.5 before entering a dissolved air flotation (DAF) tank. After DAF treatment, the wastewater entered a biological contact oxidation tank equipped with microporous aeration discs at the bottom to provide oxygen for the microorganisms. The retention time in this tank was 10 hours. At the upstream end of the loaded Fenton oxidation tank, the wastewater pH was adjusted to 5, and 30% hydrogen peroxide was added at a dosage of 0.5 kg / t water. The retention time in this tank was 2.5 hours. At the downstream end of the loaded Fenton oxidation tank, the wastewater pH was adjusted to 7.5 to facilitate subsequent biochemical reactions. The hydraulic retention time in the aerobic MBR tank was 20 hours. The effluent from the aerobic MBR tank enters the ozone catalytic oxidation tower, with a 30% hydrogen peroxide dosage of 0.25 kg / t water and an ozone dosage of 8 kg / t water. The effluent then flows by gravity into the breakpoint chlorination and denitrification tank. A 10% sodium hypochlorite solution is added to the breakpoint chlorination and denitrification tank to remove ammonia nitrogen, with a chloride to ammonia mass ratio of 10:1. A flowing carbon filter is used as a backup process to further treat organic matter and ammonia nitrogen in the water. The measured COD of the effluent is 617 mg / L.

[0055] Comparative Example 5

[0056] Liquid nitrile rubber wastewater with a pH of 9.62 and a COD of 9820 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 1000 and a high-gravity factor of 30, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.5 and a reaction time of 30 min, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.94, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 3, and the hydrogen peroxide and Fe... 2+ The molar ratio was 5:1, the reaction time was 30 min, and the reaction temperature was 40℃. After the reaction, solid-liquid separation was performed by pressure filtration. The separated sludge, along with other system sludge, was dehydrated and transported for external treatment. The filtrate obtained from solid-liquid separation entered the distillation unit, where atmospheric distillation was performed at a top temperature of 60℃ and a bottom temperature of 125℃ for 35 min. After distillation, the pH of the wastewater was adjusted to 6, and the COD of the resulting wastewater was 1034 mg / L.

[0057] Comparative Example 6

[0058] Liquid nitrile rubber wastewater with a pH of 8.94 and a COD of 13650 mg / L was collected. The wastewater entered a high-gravity stripping unit using nitrogen gas at a gas-to-liquid ratio of 200 and a high-gravity factor of 40, stripping away most of the volatile organic compounds. The stripped gas then entered a gas separation unit for the concentration, separation, and resource utilization of acrylonitrile monomers, as well as the recycling of nitrogen. The treated wastewater then entered an ozone oxidation unit with an ozone dosage to COD mass ratio of 0.5 and a reaction time of 30 min, further degrading the organic matter in the wastewater through the combined effects of stripping and oxidation. At the end of the reaction, the wastewater pH was 2.58, and it then entered a Fenton oxidation unit. The COD mass ratio of the wastewater after hydrogen peroxide and ozone oxidation was 2, and the hydrogen peroxide and Fe... 2+ The molar ratio was 3:1, the reaction time was 30 min, and the reaction temperature was 40℃. After the reaction, solid-liquid separation was performed by pressure filtration. The separated sludge, along with other system sludge, was dewatered and transported for disposal. The filtrate obtained from solid-liquid separation entered the distillation unit for atmospheric pressure distillation. Due to the high concentration of volatile organic compounds in the wastewater, a large amount of foam was generated immediately after distillation began, filling the distillation unit and posing a safety risk; therefore, the reaction was not continued. The COD of the wastewater before entering the distillation unit was measured to be 3370 mg / L.

[0059] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for treating liquid nitrile rubber wastewater, characterized in that, Includes the following steps: S1, Nitrile rubber wastewater was subjected to hypergravity stripping under nitrogen protection. The hypergravity stripping conditions were: hypergravity factor 50-100, gas-liquid ratio 500-2500. S2, the wastewater treated in step S1 is then subjected to ozone oxidation and Fenton oxidation in sequence; S3. The wastewater treated in step S2 is subjected to solid-liquid separation to obtain liquid components. The liquid components are then distilled and the pH is adjusted to meet the discharge standards.

2. The method for treating liquid nitrile rubber wastewater according to claim 1, characterized in that, It also includes a step of gas separation of the gas after the hypergravity blow-off in step S1.

3. The method for treating liquid nitrile rubber wastewater according to claim 2, characterized in that, Gas separation is performed using a gas separation membrane, which is one or more of inorganic and / or organic membranes.

4. The method for treating liquid nitrile rubber wastewater according to claim 1, characterized in that, The ozone oxidation conditions are as follows: the ratio of ozone dosage to COD of the stripped wastewater is 0.5 to 1, and the reaction time is 30 to 60 minutes.

5. The method for treating liquid nitrile rubber wastewater according to claim 1, characterized in that, Fenton oxidation conditions are: the ratio of hydrogen peroxide dosage to COD mass of wastewater after ozone oxidation treatment is 0.1–3, and the concentrations of hydrogen peroxide and Fe are... 2+ The molar ratio is 1:1 to 5:1, the reaction time is 30 to 60 min, and the reaction temperature is 40 to 65℃.

6. The method for treating liquid nitrile rubber wastewater according to claim 1, characterized in that, In step S3, the distillation method is either atmospheric distillation or vacuum distillation.

7. The method for treating liquid nitrile rubber wastewater according to claim 6, characterized in that, The temperature at the top of the atmospheric distillation column is not greater than 95℃, the temperature at the bottom of the column is not less than 120℃, and the residence time is 30 to 90 minutes.

8. The method for treating liquid nitrile rubber wastewater according to claim 6, characterized in that, The vacuum distillation pressure is 0.08–0.095 MPa, the temperature is 40–80 °C, and the residence time is 10–60 min.

9. The method for treating liquid nitrile rubber wastewater according to claim 1, characterized in that, The COD of the nitrile rubber wastewater is 5000-20000 mg / L.

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