Treatment method of rectification wastewater containing dimethyl sulfoxide

Abstract

The invention discloses a method for treating rectification wastewater containing dimethyl sulfoxide. The method comprises the following steps: carrying out oxidation treatment on rectification wastewater containing dimethyl sulfoxide by adopting micro-nano bubble reinforced dielectric barrier discharge, adsorbing and concentrating volatile organic compounds generated in a dimethyl sulfoxide oxidation process by using an activated carbon laminate, and introducing the volatile organic compounds into a micro-nano bubble generator as a gas source after high-temperature steam desorption, after entering the water, hydroxyl radicals and active oxygen molecules generated by dielectric barrier discharge are oxidized into carbon dioxide, the carbon dioxide reacts with sodium hydroxide in the water, the air pressure balance of the system is kept, the pH value of the water body is reduced, and the final effluent can be directly used as the inlet water of the reclaimed water recycling system for recycling.

Description

Technical Field

[0001] The invention belongs to the field of wastewater treatment and relates to a method for treating distillation wastewater containing dimethyl sulfoxide. Background Art

[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, increase efficiency and clean production. When recovering solvents, caustic soda is usually added to keep the system alkaline, effectively inhibiting the decomposition of dimethyl sulfoxide, thereby increasing the yield of distillation products. However, dimethyl sulfoxide is inevitably residual in the distilled water. Since the reverse osmosis membranes used in the reclaimed water reuse system are mostly aromatic polyamides, 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. At present, the main method for treating refractory organic wastewater is 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 will be generated during the treatment process, and a waste gas treatment device is required. In addition, the volatile organic matter remaining in the water body is emitted into the air during the reverse osmosis concentration stage of reclaimed water reuse, enriched and accumulated, which endangers the health of employees.

[0003] Dielectric barrier discharge is a type of electrochemical oxidation and a low-temperature plasma technology, also known as silent discharge. It is usually driven by a sinusoidal AC power supply. As the voltage increases, the gas in the discharge system gradually discharges from the insulating state and is eventually broken down to form a fully discharged state. Due to the presence of the 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 lies in the environment in which the discharge area is located. When the discharge area is in the liquid phase, the energy utilization rate is reduced because a lot of energy is consumed by heating the water body to form water vapor. When the discharge area is in the air, the initiation difficulty is low and the energy utilization rate is high. The high-voltage electrode is not in direct contact with water, and no short-circuit current is generated, which protects the electrode and is almost unaffected by water quality. However, the gas-liquid mass transfer area is small, and the utilization rate of active substances such as short-lived hydroxyl radicals is lower than that of 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 extend the reaction time.

[0004] Micro-nano bubbles refer to bubbles with a particle size between 10nm and 100μm, which have some unique properties: (1) larger specific surface area and internal pressure. For gas-liquid two-phase reaction processes, this directly increases the gas-liquid interface area and improves mass transfer efficiency; (2) long residence time in water. According to the Stokes equation, the rising speed of bubbles is proportional to the size of bubbles, so micro-nano bubbles have a smaller rising speed in water, and thus have a longer residence time in water; (3) hydroxyl free radicals can be generated. During the contraction process of micro-nano bubbles, the charge density of the double electric layer increases rapidly. At the moment of bubble rupture, due to the drastic change of the disappearance of the gas-liquid interface, the high concentration of ions accumulated on the interface can instantly release the accumulated chemical energy, and the strong oxidizing property of hydroxyl free radicals can be used to degrade organic pollutants. In the process of dielectric barrier discharge treatment of wastewater, the introduction of micro-nano bubbles can effectively improve the mass transfer efficiency and enhance the discharge oxidation effect.

[0005] Chinese patent application CN118619441A discloses an advanced oxidation device and method of submerged dielectric barrier discharge plasma coupled micro-nano bubbles, using active gas generated by plasma as the gas source of the micro-nano bubble generator, and the integrated device uses high-efficiency active substances in situ. When the gas volume is large, the bubbles carry the volatile substances in the water into the atmosphere. However, although this method achieves water purification, the waste gas generated needs to be further processed by other equipment. Summary of the invention

[0006] The object of the present invention is to provide a method for treating distillation wastewater containing dimethyl sulfoxide. The method targets the effluent of a dimethyl sulfoxide distillation recovery system, i.e., distillation wastewater containing dimethyl sulfoxide, and uses microbubbles in coordination with dielectric barrier discharge to simultaneously treat wastewater and waste gas without secondary pollution and without the need for a matching waste gas treatment device, and can be used as influent of a reclaimed water reuse system.

[0007] The technical solution for achieving the purpose of the present invention is as follows:

[0008] A method for treating distillation wastewater containing dimethyl sulfoxide comprises the following steps:

[0009] (1) Distillation wastewater containing dimethyl sulfoxide is passed into a container with a ground electrode and a high-voltage electrode. The surface of the electrode is covered with an insulating medium, and an activated carbon layer is arranged above the container. Liquid phase discharge is adopted, the water surface is higher than the plane where the ground electrode is located, and the power is turned on to start discharge;

[0010] (2) Turn on the micro-nano bubble generator, adjust the working flow, use air as the gas source, adjust the ventilation volume, strengthen the discharge oxidation process, and complete the oxidation and decomposition of dimethyl sulfoxide. The volatile organic matter generated during the oxidation process is adsorbed and concentrated by the activated carbon layer;

[0011] (3) Stop using air as the gas source for the micro-nano bubble generator, introduce steam to heat the activated carbon layer, connect the desorbed high-concentration volatile organic matter to the micro-nano bubble generator as the gas source, and introduce it into the water body again for oxidation reaction. The volatile organic matter is oxidized and decomposed into carbon dioxide, which reacts with the sodium hydroxide in the wastewater to reduce the pH of the water body.

[0012] Furthermore, 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.

[0013] Furthermore, 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 to 0.5 times the thickness of the flat plate electrode.

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

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

[0016] Furthermore, in step (2), the discharge oxidation reaction time is 10 to 60 minutes.

[0017] Furthermore, in step (3), the steam adopts the distillation steam in the dimethyl sulfoxide distillation recovery system.

[0018] Furthermore, in step (3), the steam volume is 2 to 60 m 3 / h, heating time is 10 to 20 minutes, and reaction time is 10 to 20 minutes.

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

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

[0021] (2) The present invention provides a waste gas re-treatment process, and dimethyl sulfide and dimethyl disulfide and other volatile organic compounds with odor generated by the oxidation and decomposition of dimethyl sulfoxide are adsorbed and concentrated by activated carbon layers. The adsorbed volatile organic compounds are desorbed after steam heating and are introduced into the waste water again as the gas source of the micro-nano bubble generator, and are oxidized and decomposed in the discharge oxidation process, thereby achieving waste gas treatment.

[0022] (3) The carbon dioxide generated by the oxidation reaction of volatile organic matter in the present invention can react with the sodium hydroxide originally present in the wastewater, while maintaining the air pressure balance inside and outside the device, reducing the pH of the water body to 7.0-8.5. The effluent can be directly used as the inlet water for the subsequent reverse osmosis concentration stage of recycled water reuse, without adjusting the inlet pH, avoiding affecting the reverse osmosis membrane and reducing the desalination rate, and will not cause waste gas enrichment and endanger the health of employees. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of a device for treating distillation wastewater containing dimethyl sulfoxide using micro-nano bubbles in cooperation with dielectric barrier discharge;

[0024] Figure 2 The present invention is a schematic flow chart of a method for treating distillation wastewater containing dimethyl sulfoxide. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0026] Example 1

[0027] The test water volume is 1t. According to liquid phase detection, the concentration of dimethyl sulfoxide in the distillation wastewater to be treated is 796mg / L and the pH is 9.3. The distillation wastewater is passed into a container with a grounding electrode and a high-voltage electrode. The surface of the electrode is covered with an insulating medium, and an activated carbon layer is set above the container. The water surface is higher than the plane where the grounding electrode is located. Turn on the power, adjust the discharge voltage to 6kV, the thickness of the flat electrode to 1cm, the thickness of the insulating medium to 0.5cm, turn on the micro-nano bubble generator, and adjust the working flow rate to 15m 3 / h, using air as the gas source, the gas flow rate is 9m 3 / h, discharge oxidation reaction for 60min, the volatile organic matter generated in the oxidation process is adsorbed and concentrated by the activated carbon layer above. Then stop using air as the gas source for the micro-nano bubble generator, and introduce steam to heat the activated carbon layer. The steam flow rate is 60m 3 / h, heating time 10min, the desorbed high concentration volatile organic matter as the gas source connected to the micro-nano bubble generator, the reaction continued for 20min, the volatile organic matter was oxidized and decomposed into carbon dioxide, after the reaction was completed, the residual dimethyl sulfoxide concentration in the water was measured to be 26mg / L, pH 7.1. During the reaction process, the concentrations of dimethyl sulfide and dimethyl disulfide in the exhaust gas were measured to be 4.8mg / m 3 and 2.2 mg / m 3 After the reaction, the concentrations of both were below the detection limit. The effluent entered the subsequent water reuse system without accumulation of volatile organic matter.

[0028] Comparative Example 1

[0029] Take the distillation wastewater with a dimethyl sulfoxide concentration of 796 mg / L in Example 1, do not turn on the micro-nano bubble generator, and perform the same operations as in Example 1. The residual dimethyl sulfoxide concentration in the water is 559 mg / L. After the reaction is completed, the concentrations of dimethyl sulfide and dimethyl disulfide in the waste gas are 5.5 mg / m 3 and 2.9 mg / m 3 The pH of the water body is 8.9, and the effluent enters the subsequent reclaimed water reuse system, where volatile organic matter is enriched and accumulated.

[0030] Comparative Example 2

[0031] Take the distillation wastewater with a dimethyl sulfoxide concentration of 796 mg / L in Example 1, do not turn on the micro-nano bubble generator, the reaction time is 120 min, and the other operations are the same as in Example 1. The residual dimethyl sulfoxide concentration is measured to be 483.2 mg / L. After the reaction is completed, the concentrations of dimethyl sulfide and dimethyl disulfide in the waste gas are measured to be 3.6 mg / m 3 and 1.6 mg / m 3 The water pH is 9.1, and the effluent enters the subsequent reclaimed water reuse system, where volatile organic matter is enriched and accumulated.

[0032] Example 2

[0033] The test water volume is 1t. According to liquid phase detection, the concentration of dimethyl sulfoxide in the distillation wastewater to be treated is 515mg / L and the pH is 9.7. The distillation wastewater is passed into a container with a grounding electrode and a high-voltage electrode. The surface of the electrode is covered with an insulating medium, and an activated carbon layer is set above the container. The water surface is higher than the plane where the grounding electrode is located. Turn on the power, adjust the discharge voltage to 4kV, the thickness of the flat electrode to 1cm, the thickness of the insulating medium to 0.3cm, turn on the micro-nano bubble generator, and adjust the working flow rate to 10m 3 / h, using air as the gas source, the gas flow rate is 6m 3 / h, discharge oxidation reaction for 30min, the volatile organic matter generated in the oxidation process is adsorbed and concentrated by the activated carbon layer above. Then stop using air as the gas source for the micro-nano bubble generator, and introduce steam to heat the activated carbon layer. The steam flow rate is 30m 3 / h, heating time 20min, the desorbed high concentration volatile organic matter as the gas source connected to the micro-nano bubble generator, the reaction continued for 20min, the volatile organic matter was oxidized and decomposed into carbon dioxide, after the reaction was completed, the residual dimethyl sulfoxide concentration in the water was measured to be 18mg / L, and the water pH was 7.4. During the reaction process, the concentrations of dimethyl sulfide and dimethyl disulfide in the exhaust gas were measured to be 2.6mg / m 3 and 1.1 mg / m 3After the reaction, the concentrations of both were lower than the detection limit, and the effluent entered the subsequent reclaimed water reuse system without any accumulation of volatile organic matter.

[0034] The above description is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto, and any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for treating distillation wastewater containing dimethyl sulfoxide, characterized in that: The following steps are involved: (1) The distillation wastewater containing dimethyl sulfoxide is passed into a container with a ground electrode and a high-voltage electrode. The surface of the electrode is covered with an insulating medium, and an activated carbon layer is set above the container. Liquid phase discharge is adopted. The water surface is higher than the plane where the ground electrode is located. Turn on the power and start discharge; (2) Turn on the micro-nano bubble generator, adjust the working flow, use air as the gas source, adjust the ventilation volume, strengthen the discharge oxidation process, and complete the oxidation and decomposition of dimethyl sulfoxide. The volatile organic compounds generated during the oxidation process are adsorbed and concentrated by the activated carbon layer; (3) Stop using air as the gas source for the micro-nano bubble generator, introduce steam to heat the activated carbon layer, connect the desorbed high-concentration volatile organic matter to the micro-nano bubble generator as the gas source, and introduce it into the water body again for oxidation reaction. The volatile organic matter is oxidized and decomposed into carbon dioxide, and reacts with the 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 ground electrode are parallel plate electrodes, the insulating medium is one of quartz, ceramic, organic glass and mica, and the thickness is 0.1 to 0.5 times the thickness of the flat plate electrode.

4. The processing method according to claim 1, characterized in that: In step (1), the discharge voltage is set to 4~10kV.

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

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

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

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

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