A method for treating dimethyl sulfoxide-containing rectification wastewater

Abstract

The application discloses a treatment method of dimethyl sulfoxide-containing rectification wastewater. The method adopts micro-nano bubble reinforced dielectric barrier discharge oxidation to treat the dimethyl sulfoxide-containing rectification wastewater, and an activated carbon layer plate is used to adsorb and concentrate volatile organic compounds generated in the dimethyl sulfoxide oxidation process. The volatile organic compounds are desorbed by steam at high temperature, and then are introduced into a micro-nano bubble generator as a gas source. The volatile organic compounds are oxidized into carbon dioxide by hydroxyl radicals and active oxygen molecules generated by the dielectric barrier discharge after entering water. The carbon dioxide reacts with sodium hydroxide in water, so that the system gas pressure balance is maintained, the water body pH is reduced, and finally the effluent can be directly used as influent of a reclaimed water reuse system for reuse.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wastewater treatment, and relates to a treatment method for dimethyl sulfoxide-containing rectification wastewater. BACKGROUND

[0002] With the rapid development of industrialization, especially in the production process of high-end materials such as carbon fiber, dimethyl sulfoxide is widely used as an important solvent. Effective recovery of dimethyl sulfoxide in production wastewater is an important measure for enterprises to reduce costs and increase efficiency and clean production. When the solvent is recovered, flake alkali is usually added to keep the system alkaline, effectively inhibiting the decomposition of dimethyl sulfoxide, thereby improving the yield of rectification products. However, the rectification water inevitably contains residual dimethyl sulfoxide. Since the reverse osmosis membrane used in the water reuse system is mostly aromatic polyamide, dimethyl sulfoxide as a universal solvent will cause irreversible damage to the reverse osmosis membrane, resulting in a decrease in the quality of the produced water. The main method for treating difficult-to-degrade organic wastewater at present is the advanced oxidation process, such as Fenton oxidation, photocatalytic oxidation and electrochemical oxidation, which mainly uses the generated hydroxyl radicals to oxidize organic matter, but waste gas is generated during the treatment process, which requires a waste gas treatment device, and the volatile organic compounds remaining in the water body are enriched and accumulated in the air during the reverse osmosis concentration stage of the water reuse, which endangers the health of employees.

[0003] Dielectric barrier discharge is a kind of electrochemical oxidation, which is a low-temperature plasma technology, also known as silent discharge, usually driven by a sinusoidal alternating current power supply. With the increase of voltage, the gas in the discharge system gradually discharges from the insulating state to the completely discharged state. Due to the presence of insulating medium, no sparks or arcs are generated during the discharge process, reducing energy loss. Dielectric barrier discharge can be divided into gas phase discharge and liquid phase discharge, the main difference being the environment in which the discharge region is located. When the discharge region is in the liquid phase, the energy utilization rate decreases because the heating of the water body to form water vapor consumes a large amount of energy. When the discharge region is in the air, the initiation difficulty is low, the energy utilization rate is high, the high-voltage electrode does not directly contact the water, no short-circuit current is generated, the electrode is protected, and it is almost not affected by water quality. However, the gas-liquid mass transfer area is small, and the active substances such as hydroxyl radicals with short life have a lower utilization rate than in the liquid phase. The technical difficulty of dielectric barrier discharge lies in the efficient utilization of active substances, that is, it is necessary to improve the gas-liquid mass transfer efficiency and prolong the reaction time.

[0004] Micro-nano bubbles refer to bubbles with a particle size of 10 nm to 100 pm, which have some unique properties: (1) larger specific surface area and internal pressure, which directly increases the gas-liquid phase interface area and improves the mass transfer efficiency for gas-liquid two-phase reaction process; (2) longer residence time in water, as the bubble rising speed is proportional to the bubble size according to Stokes equation, so the micro-nano bubbles have a smaller rising speed in water, and thus have a longer residence time in water; (3) can generate hydroxyl radicals, in the contraction process of micro-nano bubbles, the charge density of the double electric layer increases rapidly, and due to the rapid change of the disappearance of the gas-liquid interface, the high-concentration ions accumulated on the interface can release the accumulated chemical energy instantaneously, and the strong oxidation of hydroxyl radicals can be used to degrade organic pollutants. In the process of treating wastewater by dielectric barrier discharge, micro-nano bubbles are introduced to effectively improve the mass transfer efficiency and strengthen the discharge oxidation effect.

[0005] Chinese patent application CN118619441A discloses a kind of liquid under dielectric barrier discharge plasma coupling micro-nano bubble advanced oxidation device and method, using active gas generated by plasma as the gas source of micro-nano bubble generator, integrated equipment uses high-efficiency active substance in situ, when gas volume is large, bubble carries volatile substances in water and discharges into atmosphere. However, although this method realizes the purification of water body, the generated waste gas needs to be further treated by another device. SUMMARY

[0006] The purpose of the present application is to provide a method for treating dimethyl sulfoxide-containing rectification wastewater. This method uses micro-bubbles in conjunction with dielectric barrier discharge to treat the effluent from the dimethyl sulfoxide rectification recovery system, i.e., dimethyl sulfoxide-containing rectification wastewater, simultaneously treating the wastewater and waste gas without secondary pollution, without the need for a supporting waste gas treatment device, and can be used as the influent for a water reuse system.

[0007] The technical solution to achieve the purpose of the present application is as follows:

[0008] A method for treating dimethyl sulfoxide-containing rectification wastewater, comprising the following steps:

[0009] (1) passing the dimethyl sulfoxide-containing rectification wastewater into a container with a grounding electrode and a high-voltage electrode, the electrode surface being covered with an insulating medium, and an activated carbon layer plate being provided above the container, using liquid-phase discharge, the water surface being higher than the plane where the grounding electrode is located, turning on the power supply to start the discharge;

[0010] (2) turning on the micro-nano bubble generator, adjusting the working flow rate, using air as the gas source, adjusting the aeration amount, strengthening the discharge oxidation process, and completing the oxidation and decomposition of dimethyl sulfoxide, the volatile organic compounds generated in the oxidation process being adsorbed and concentrated by the activated carbon layer plate;

[0011] (3) stop using air as the micro-nano bubble generator gas source, pass steam to heat the activated carbon plate, use the desorbed high-concentration volatile organic compounds as the gas source to connect the micro-nano bubble generator, and then pass into the water body again to perform oxidation reaction, the volatile organic compounds are oxidized and decomposed into carbon dioxide, and react with sodium hydroxide in the wastewater to reduce the pH of the water body.

[0012] Further, in step (1), the concentration of dimethyl sulfoxide in the rectified wastewater is 100-1000 mg / L, and the pH is 9.0-10.5.

[0013] Further, in step (1), the high-voltage electrode and the grounding electrode are parallel plate electrodes, the insulating medium is one of quartz, ceramic, organic glass and mica, and the thickness is 0.1-0.5 times the thickness of the plate electrode.

[0014] Further, in step (1), the discharge voltage is set to 4-10 kV.

[0015] Further, in step (2), the working flow of the micro-nano bubble generator is 5m 3 / h-60m 3 / h, and the gas flow is 0.4-1 times the working flow.

[0016] Further, in step (2), the discharge oxidation reaction time is 10-60 min.

[0017] Further, in step (3), the steam is the rectification steam in the dimethyl sulfoxide rectification recovery system.

[0018] Further, in step (3), the steam amount is 2-60m 3 / h, the heating time is 10-20 min, and the reaction time is 10-20 min.

[0019] Compared with the prior art, the present application has the following advantages:

[0020] (1) The present application uses micro-nano bubbles to cooperate with dielectric barrier discharge to treat rectified wastewater containing dimethyl sulfoxide, the micro-nano bubbles increase the gas-liquid contact area in the discharge oxidation process, enhance the gas-liquid disturbance mixing, and prolong the contact time, thereby strengthening the oxidation effect and further reducing the residual concentration of dimethyl sulfoxide in the water.

[0021] (2) The present application sets up a waste gas reprocessing process, the volatile organic compounds such as dimethyl sulfide and dimethyl disulfide generated by the oxidation and decomposition of dimethyl sulfoxide have an odor, which are adsorbed and concentrated by the activated carbon plate. The adsorbed volatile organic compounds are desorbed after being heated by steam, and then connected to the wastewater again as the gas source of the micro-nano bubble generator, and oxidized and decomposed in the discharge oxidation process, realizing waste gas treatment.

[0022] (3)The carbon dioxide generated by the oxidation reaction of volatile organic matters can react with sodium hydroxide originally existing in the wastewater, maintain the balance of air pressure inside and outside the device, reduce the pH of the water body to 7.0-8.5, and the effluent can be directly used as the influent of the reverse osmosis concentration stage in the subsequent reclaimed water reuse system, without adjusting the pH of the influent, avoiding affecting the reverse osmosis membrane and reducing the desalination rate, and without causing waste gas enrichment and endangering the health of employees. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A schematic diagram of a device for treating dimethyl sulfoxide-containing rectification wastewater by micro-nano bubble synergistic dielectric barrier discharge;

[0024] Figure 2 A flowchart of a method for treating dimethyl sulfoxide-containing rectification wastewater. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below with examples. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0026] Example 1

[0027] The test water quantity was 1 t, and the dimethyl sulfoxide concentration in the rectification wastewater to be treated was 796 mg / L and the pH was 9.3 by liquid phase detection. The rectification wastewater was introduced into a container with a grounding electrode and a high-voltage electrode, the electrode surface was covered with an insulating medium, and an activated carbon layer plate was arranged at the upper part of the container, the water surface was higher than the plane where the grounding electrode was located, the power supply was turned on, the discharge voltage was adjusted to 6 kV, the thickness of the flat plate electrode was 1 cm, the thickness of the insulating medium was 0.5 cm, the micro-nano bubble generator was turned on, the working flow was adjusted to 15 m 3 / h, air was used as the gas source, the gas flow was 9 m 3 / h, the discharge oxidation reaction was carried out for 60 min, and the volatile organic matters generated in the oxidation process were adsorbed and concentrated by the activated carbon layer plate above. Then, air was stopped as the gas source of the micro-nano bubble generator, steam was introduced to heat the activated carbon layer plate, the steam flow was 60 m 3 / h, the heating time was 10 min, the desorbed high-concentration volatile organic matters were connected to the micro-nano bubble generator as the gas source, and the reaction was continued for 20 min, the volatile organic matters were oxidized and decomposed into carbon dioxide, and the residual dimethyl sulfoxide concentration in the effluent was 26 mg / L and the pH was 7.1 after the reaction was completed. The dimethyl sulfide and dimethyl disulfide concentrations in the waste gas were 4.8 mg / m 3 and 2.2 mg / m 3 , respectively, during the reaction, and the concentrations of both were lower than the detection limit after the reaction was completed. The effluent entered the subsequent reclaimed water reuse system, and there was no enrichment and accumulation of volatile organic matters.

[0028] Comparative Example 1

[0029] The dimethyl sulfoxide concentration of the rectification wastewater in Example 1 was 796 mg / L, the micro-nano bubble generator was not started, and the rest of the operations were the same as in Example 1. The residual dimethyl sulfoxide concentration in the effluent was measured to be 559 mg / L. After the reaction was completed, the dimethyl sulfide and dimethyl disulfide concentrations in the exhaust gas were measured to be 5.5 mg / m 3 and 2.9 mg / m 3 , respectively, the water body pH was 8.9, and the effluent entered the subsequent reclaimed water reuse system, with volatile organic compounds accumulating.

[0030] Comparative Example 2

[0031] The dimethyl sulfoxide concentration of the rectification wastewater in Example 1 was 796 mg / L, the micro-nano bubble generator was not started, and the reaction time was 120 min, and the rest of the operations were the same as in Example 1. The residual dimethyl sulfoxide concentration was measured to be 483.2 mg / L. After the reaction was completed, the dimethyl sulfide and dimethyl disulfide concentrations in the exhaust gas were measured to be 3.6 mg / m 3 and 1.6 mg / m 3 , respectively, the water body pH was 9.1, and the effluent entered the subsequent reclaimed water reuse system, with volatile organic compounds accumulating.

[0032] Example 2

[0033] The test water volume was 1 t, and the dimethyl sulfoxide concentration of the rectification wastewater to be treated was 515 mg / L, and the pH was 9.7, as detected by liquid phase detection. The rectification wastewater was introduced into a container with a grounding electrode and a high-voltage electrode, the electrode surface was covered with an insulating medium, and an activated carbon layer plate was arranged at the top of the container. The water surface was higher than the plane where the grounding electrode was located. The power supply was turned on, the discharge voltage was adjusted to 4 kV, the thickness of the flat electrode was 1 cm, the thickness of the insulating medium was 0.3 cm, the micro-nano bubble generator was started, the working flow was adjusted to 10 m 3 / h, air was used as the gas source, the gas flow was 6 m 3 / h, the discharge oxidation reaction was carried out for 30 min, and the volatile organic compounds generated during the oxidation process were adsorbed and concentrated by the activated carbon layer plate above. Then, the air was stopped as the gas source of the micro-nano bubble generator, steam was introduced to heat the activated carbon layer plate, the steam flow was 30 m 3 / h, the heating time was 20 min, the desorbed high-concentration volatile organic compounds were used as the gas source to be connected to the micro-nano bubble generator, and the reaction was continued for 20 min. The volatile organic compounds were oxidized and decomposed into carbon dioxide. After the reaction was completed, the residual dimethyl sulfoxide concentration in the effluent was measured to be 18 mg / L, and the water body pH was 7.4. During the reaction, the dimethyl sulfide and dimethyl disulfide concentrations in the exhaust gas were measured to be 2.6 mg / m 3 and 1.1 mg / m 3After the reaction, the concentrations of both are lower than the detection limit, and the effluent enters the subsequent reclaimed water reuse system without accumulation of volatile organic compounds.

[0034] The above merely describes the preferred embodiments of the present application, but the protection scope of the present application is not limited thereto, and any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for treating distillation wastewater containing dimethyl sulfoxide, characterized in that, Includes the following steps: (1) Pass the distillation wastewater containing dimethyl sulfoxide into a container with a grounding electrode and a high-voltage electrode. The electrode surface is covered with an insulating medium, and an activated carbon plate is set on the upper part of the container. The liquid phase discharge is adopted, the water level is higher than the plane where the grounding electrode is located, the power is turned on, and the discharge is started. The discharge voltage is set to 4~10kV. (2) Turn on the micro-nano bubble generator, adjust the working flow rate, use air as the gas source, adjust the ventilation volume, strengthen the discharge oxidation process, and complete the oxidation decomposition of dimethyl sulfoxide. The volatile organic compounds generated during the oxidation process are adsorbed and concentrated by the activated carbon plate. (3) Stop using air as the gas source for the micro-nano bubble generator, introduce steam to heat the activated carbon plate, and use the desorbed high concentration of volatile organic compounds as the gas source to connect to the micro-nano bubble generator. Then, introduce it into the water body again to carry out the oxidation reaction. The volatile organic compounds are oxidized and decomposed into carbon dioxide, and react with sodium hydroxide in the wastewater to reduce the pH of the water body.

2. The processing method according to claim 1, characterized in that, In step (1), the concentration of dimethyl sulfoxide in the distillation wastewater is 100~1000 mg / L and the pH is 9.0~10.

5.

3. The processing method according to claim 1, characterized in that, In step (1), the high-voltage electrode and the grounding electrode are parallel plate electrodes, and the insulating medium is one of quartz, ceramic, plexiglass and mica, with a thickness of 0.1 to 0.5 times that of the plate electrode.

4. The processing method according to claim 1, characterized in that, In step (2), the working flow rate of the micro / nano bubble generator is 5 m³ / s. 3 / h~60m 3 / h, the gas flow rate is 0.4 to 1 times the working flow rate.

5. The processing method according to claim 1, characterized in that, In step (2), the discharge oxidation reaction time is 10~60 min.

6. The processing method according to claim 1, characterized in that, In step (3), the steam used is the distillation steam from the dimethyl sulfoxide distillation recovery system.

7. The processing method according to claim 1, characterized in that, In step (3), the steam volume is 2~60m³. 3 / h, heating time is 10~20min, oxidation reaction time is 10~20min.

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