Pretreatment process of amine liquid regeneration waste alkali liquid

Abstract

The invention discloses a pretreatment process of amine liquid regeneration waste alkali liquid, and belongs to the technical field of wastewater treatment. The method comprises the following steps: (1) carrying out primary homogeneous regulation on the amine liquid regeneration waste alkali liquid, and then carrying out pressurization treatment to obtain treated amine liquid regeneration waste alkali liquid; the method comprises the following steps: carrying out primary homogeneous regulation on monomer recovery unit external drainage from a nitrile rubber generation device to obtain treated external drainage; (2) carrying out primary electrolysis on the treated amine liquid regeneration waste alkali liquid and the treated discharged water to obtain primary electrolysis effluent; (3) carrying out secondary homogeneous regulation on primary electrolysis effluent; (4) performing secondary electrolysis on the effluent in the step (3) to obtain secondary electrolysis effluent; and (5) adding a precipitator into the secondary electrolysis effluent, carrying out precipitation reaction, refluxing part of the effluent after the reaction, and feeding the rest of the effluent into a deep treatment device. According to the treatment process, the content of toxic pollutants such as sulfides and organic amines in the waste alkali liquid can be rapidly reduced, the biodegradability of the waste alkali liquid is remarkably improved, and good conditions are created for subsequent deep treatment.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular relates to a pretreatment process for waste alkali liquid of amine liquid regeneration. Background Art

[0002] At present, the catalytic desulfurization, hydrogenation and sulfur recovery units of refineries usually use the alcohol amine process to absorb acid gases such as H2S and CO2 in gas, liquefied gas, light hydrocarbons and sulfur reduction gas. The rich amine liquid enters the solvent regeneration system, releases the acid gas by increasing the temperature, and enters the sulfur recovery unit as a raw material, while the lean amine liquid is recycled. During the amine liquid recycling and regeneration process, a small amount of unremoved acid gas in the solution forms thermally stable salts. As the concentration of thermally stable salts gradually increases, it will affect the long-term operation of the desulfurization unit. The amine liquid is often desalted by resin adsorption. After the resin adsorption is saturated, NaOH is used for regeneration, thus producing a high-concentration alkaline and toxic amine liquid regeneration waste alkali liquid. The wastewater is strongly alkaline, with a high sulfide content, a pungent odor and biological toxicity. It contains N-methyldiethanolamine, organic salts and inorganic salts, COD of about 85000mg / L, total nitrogen of about 6000mg / L, sulfide of about 7000mg / L, and conductivity of about 60000μS.cm -1 , directly entering the biochemical system will cause serious impact.

[0003] The core of amine liquid regeneration waste alkali liquid treatment is to eliminate the toxicity of organic amines and high-concentration sulfides and improve the biodegradability of wastewater. At present, common treatment methods include sending it to coking incineration treatment; multi-effect evaporation treatment, or using a combination of "desulfurization + advanced oxidation + biochemical treatment" to achieve deep treatment of wastewater.

[0004] Patent CN106554128A provides a method for treating waste alkali liquor from an amine liquid regeneration device. The waste alkali liquor is treated by the process of "electrolytic catalytic oxidation + engineered bacteria biochemistry + ozone catalytic oxidation". In the electrolysis process, the Co-activated carbon composite electrode is used as the anode and the stainless steel electrode is used as the cathode. The elemental sulfur is recycled after the sulfide is deposited on the electrode surface. The high concentration of organic matter and ammonia nitrogen are degraded by anaerobic engineered bacteria and aerobic engineered bacteria respectively. Finally, the ozone oxidation process is used to achieve the goal of COD < 60 mg / L and ammonia nitrogen < 5 mg / L. However, the actual application of this patent has too high a procurement cost for engineered bacteria. In the electrolytic desulfurization stage, the sulfur produced by electrolysis adheres to the anode plate. Although it is removed by reversing the electrode, the hydraulic retention time in the device is 0.5-1h, and the residence time of the reversal is only 5-15s. The sulfur element that is not discharged into the subsequent treatment unit in time will be re-deposited on the anode, resulting in anode passivation, which reduces the efficiency of electrolytic treatment, or is further oxidized to SO4 2- In the subsequent anaerobic treatment process, due to the presence of sulfate-reducing bacteria, SO4 2-It was restored to S 2- , affecting the stable operation of the sewage treatment system.

[0005] Patent CN107572716B discloses a deep treatment process for waste liquid generated by an amine liquid regeneration device, including five treatment units: homogenization regulation - biological desulfurization - ultraviolet oxidation - A / O1 / O2 biochemical treatment - electrolytic catalytic oxidation, which can recycle sulfides, and the final effluent COD ≤ 60 mg / L, ammonia nitrogen ≤ 5 mg / L, which meets the national emission standards. The biological desulfurization method used in the present invention has high requirements for the screening of desulfurization bacteria and the optimization of process conditions. The industrial application of this process has certain limitations, because high concentrations of S 2- It has an inhibitory and toxic effect on the biochemical system, and the tiny sulfur particles discharged from the microorganisms are in a colloidal state in the water and are difficult to precipitate naturally.

[0006] In the article "Process and Characteristics of Electrochemical Treatment of Sulfur-Containing Wastewater", written by Zhang Keqiang, a tubular electro-flotation device was used to treat artificially simulated sulfur-containing wastewater. The cathode and anode of the tubular electro-flotation device are composed of cast iron pipes with inner diameters of 50 mm and 34 mm, respectively. The anode is located in the center of the cylinder, the outer periphery is the cathode, and the bottom is a conical design. The water sample enters the top from the bottom of the reactor and is discharged. The FeS precipitate generated by the reaction enters the precipitator at the bottom. The electrolytic reactor used in this method is a sacrificial anode to achieve the purpose of removing sulfide from the water. When the amine liquid regeneration waste alkali liquid with a sulfide concentration of 7000 mg / L and a pH value of 10.2-13.2 is treated with this experimental device, a large amount of FeS precipitation will occur, and the anode needs to be replaced frequently, which affects the long-term operation of the device. In addition, FeS is a fine particle, and it takes a long time for natural sedimentation. Especially in an electrolytic device with air flotation function, it is almost impossible to naturally settle to the bottom of the equipment, and the effluent contains a large amount of black suspended matter.

[0007] In summary, most of the current treatment methods for amine regeneration waste alkali liquor have high treatment costs and are difficult to apply industrially. 2- After elemental sulfur is generated, it cannot be removed from the water in time, which increases the difficulty of deep wastewater treatment. Summary of the invention

[0008] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a pretreatment process for amine liquid regeneration of waste alkali liquid, which has the advantages of "treating waste with waste", low investment and operation costs, safety, stability, high efficiency and environmental protection. The process can quickly reduce the content of toxic pollutants such as sulfide and organic amines in the waste alkali liquid, significantly improve the biodegradability of the waste alkali liquid, and create good conditions for subsequent deep treatment.

[0009] In order to achieve the above object, according to one aspect of the present invention, a pretreatment process for waste alkali solution of amine solution regeneration is provided, comprising the following steps: (1) Primary homogenization and adjustment: The waste alkali liquor from amine regeneration is subjected to pressure treatment after primary homogenization and adjustment to obtain the treated waste alkali liquor from amine regeneration; the waste water from the monomer recovery unit of the nitrile rubber production device is subjected to primary homogenization and adjustment to obtain the treated waste water; (2) Primary electrolysis: The treated amine solution regeneration waste alkali solution and the treated external drainage are mixed in a volume ratio of 1:1-1:5 and enter the primary electrolysis reactor for primary electrolysis reaction. The working voltage of the primary electrolysis reactor is 5-25V and the current density is 10-30mA / cm 2 , the reaction temperature is 30-50°C, the reaction time is 1-3.5h, and primary electrolysis water is obtained; (3) Secondary homogenization adjustment: Acidic substances are added to the primary electrolyzed water to adjust the pH to 3-6, and secondary homogenization adjustment is performed; (4) Secondary electrolysis: The effluent from step (3) enters a secondary electrolysis reactor for secondary electrolysis reaction. The operating voltage of the secondary electrolysis reactor is 15-40V and the current density is 40-90mA / cm 2 , the reaction temperature is 40-50°C, the reaction time is 1-2.5h, and secondary electrolysis water is obtained; (5) Chemical precipitation: alkaline substances are added to the secondary electrolysis effluent to adjust the pH to 7-10. After standing for 1-2 hours, a precipitant is added to carry out a precipitation reaction for 20-40 minutes. After the reaction, the effluent is refluxed at a reflux ratio of 100-200% to the point before the acidic substances are added to adjust the pH value in step (3). The remaining effluent enters a deep treatment device.

[0010] In some embodiments, in step (2), the primary electrolysis reactor includes a primary electrolysis reactor cavity, which is formed by wrapping a shell and is provided with a plurality of electrolysis reaction chambers distributed in a honeycomb shape, each electrolysis reaction chamber is provided with a primary electrolysis anode, a primary electrolysis cathode and a water distribution plate located at the bottom, the primary electrolysis anode is located at the center of the electrolysis reaction chamber, and is 3-10 cm away from the primary electrolysis cathode; the surface of the primary electrolysis anode is coated with a double-layer corrosion-resistant mesh, and the bottom of the primary electrolysis anode is connected to a rotating motor, and the rotating motor can drive the double-layer corrosion-resistant mesh coated on the surface of the primary electrolysis anode to rotate.

[0011] In some embodiments, in step (2), a plurality of small holes are provided on the water distribution plate, the diameter of the small holes is 2-10 mm, and the small holes are evenly distributed on the entire distribution plate.

[0012] In some embodiments, the primary electrolysis anode is any one of a graphite electrode and an activated carbon electrode, and the primary electrolysis cathode is a ruthenium-coated stainless steel electrode.

[0013] In some embodiments, in step (2), the double-layer corrosion-resistant mesh covering the surface of the primary electrolysis anode is any one of a 316L stainless steel mesh and a nylon mesh.

[0014] In some embodiments, in step (2), a suspended matter collector is disposed above each electrolysis reaction chamber, and the suspended matter collector is capable of collecting suspended matter on the water surface in the electrolysis reaction chamber and transporting it to a solid-liquid separation device located outside the primary electrolysis reactor.

[0015] In some embodiments, in step (4), the secondary electrolysis reactor includes a secondary electrolysis reactor cavity, a water inlet pipe and a water outlet pipe, a vertically parallel anode plate and a cathode plate are arranged in the middle of the secondary electrolysis reactor cavity, respectively connected to the positive and negative poles of the power supply, the spacing between the anode plate and the cathode plate is 3-10 cm, and porous iron-carbon fillers are filled between the plates; one end of the water inlet pipe is connected to the secondary homogenization adjustment water outlet, and the other end is inserted in the middle of the iron-carbon filler; an ultrasonic transducer is arranged at the outer bottom of the secondary electrolysis reactor cavity, and the ultrasonic transducer is connected to the ultrasonic generator; an overflow weir is arranged at the inner upper part of the secondary electrolysis reactor cavity, and the overflow weir is connected to the secondary electrolysis reactor water outlet pipe.

[0016] In some embodiments, the ultrasonic frequency is 20-80kHz, and the ultrasonic power is 50-500w.

[0017] In some embodiments, a plurality of water inlets are provided at one end of the water inlet pipe of the secondary electrolysis reactor inserted into the middle of the iron-carbon filler, the diameter of the water inlet is 5-25 mm, and the number of the water inlets is 20-200.

[0018] In some embodiments, in step (5), the precipitant is MgCl2·6H2O and Na2HPO4·6H2O, wherein the molar ratio of the elements is n(N):n(P):n(Mg)=1:0.9-1:1-1.3.

[0019] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention provides a pretreatment process for amine regeneration waste alkali liquor, which has the advantages of "treating waste with waste", low investment and operation cost, safety, stability, high efficiency and environmental protection. By treating two highly toxic and difficult-to-degrade mixed wastewaters, namely, amine regeneration waste alkali liquor and nitrile rubber monomer recovery drainage, in sequence, the process is subjected to "two-stage electrolysis + chemical precipitation" treatment, thereby achieving the purification effects of wastewater desulfurization, nitrile removal, COD reduction and nitrogen removal, realizing the purpose of "treating waste with waste" and co-degradation of pollutants, and significantly improving the biodegradability of the treated wastewater.

[0020] (2) The present invention designs a first-stage electrolysis reactor and a second-stage electrolysis reactor with a special structure, which can achieve the S 2-The controlled oxidation of sulfur can quickly separate the generated elemental sulfur from the sewage, solving the problem of S 2- Over-oxidation completes the hydrolysis of acrylonitrile at the same time, avoiding the problem of secondary pollution in subsequent treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein: Figure 1 The present invention is a flowchart of a waste alkali solution treatment process for amine solution regeneration. Figure 1 Among them, 1 is a first homogenizing tank; 2 is a second homogenizing tank; 3 is a pressurized gas dissolving tank; 4 is a primary electrolytic reactor; 5 is a third homogenizing tank; 6 is a secondary electrolytic reactor; 7 is a chemical precipitation unit; 8 is a sludge adsorption tank; 9 is a solid-liquid separation device; 10 is a magnesium ammonium hydrogen phosphate regeneration device; 11 is a first sulfide monitor; 12 is a second sulfide monitor; 13 is a first valve; 14 is a second valve; 15 is a third valve; 16 is a fourth valve; 17 is a fifth valve; 18 is a H2S pipeline; 19 is a reflux pipeline; 20 is an acidic substance dosing device; 21 is an alkaline substance dosing device.

[0022] Figure 2 This is the front view of the first-stage electrolytic reactor.

[0023] Figure 3 A top view of the first-stage electrolysis reactor.

[0024] Among them, 4-1 is a primary electrolysis anode; 4-2 is a primary electrolysis cathode; 4-3 is a water distribution plate; 4-4 is a rotating motor; 4-5 is a primary electrolysis reaction power supply; 4-6 is a suspended matter collector; 4-7 is a shell; 4-8 is a primary electrolysis reactor cavity; 4-9 is a small hole; 4-10 is an electrolysis reaction chamber; 11 is a first sulfide monitor; 14 is a second valve; 15 is a third valve; 17 is a fifth valve.

[0025] Figure 4 This is the front view of the secondary electrolysis reactor.

[0026] Figure 5 A top view of the secondary electrolysis reactor.

[0027] Among them, 6-1 is an anode plate; 6-2 is a cathode plate; 6-3 is a secondary electrolysis reactor cavity; 6-4 is a water inlet; 6-5 is a water inlet pipe; 6-6 is a water outlet pipe; 6-7 is an overflow weir; 6-8 is an iron-carbon filler; 6-9 is an ultrasonic transducer; 6-10 is an ultrasonic generator; and 6-11 is a secondary electrolysis reaction power supply. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0029] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0030] Herein, when describing embodiments or examples, it should be understood that they are not used to limit the present invention to these embodiments or examples. On the contrary, all substitutes, improvements and equivalents of the methods and materials described in the present invention can be included in the scope limited by the claims.

[0031] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0032] The present invention provides a pretreatment process for waste alkali solution of amine solution regeneration, comprising the following steps: (1) Primary homogenization and adjustment: The waste alkali liquor from amine regeneration is subjected to pressure treatment after primary homogenization and adjustment to obtain the treated waste alkali liquor from amine regeneration; the waste water from the monomer recovery unit of the nitrile rubber production device is subjected to primary homogenization and adjustment to obtain the treated waste water; (2) Primary electrolysis: The treated amine solution regeneration waste alkali solution and the treated external drainage are mixed in a volume ratio of 1:1-1:5 and enter the primary electrolysis reactor for primary electrolysis reaction. The working voltage of the primary electrolysis reactor is 5-25V and the current density is 10-30mA / cm 2 , the reaction temperature is 30-50°C, the reaction time is 1-3.5h, and primary electrolysis water is obtained; (3) Secondary homogenization adjustment: Acidic substances are added to the primary electrolyzed water to adjust the pH to 3-6, and secondary homogenization adjustment is performed; (4) Secondary electrolysis: The effluent from step (3) enters a secondary electrolysis reactor for secondary electrolysis reaction. The operating voltage of the secondary electrolysis reactor is 15-40V and the current density is 40-90mA / cm 2 , the reaction temperature is 40-50°C, the reaction time is 1-2.5h, and secondary electrolysis water is obtained; (5) Chemical precipitation: alkaline substances are added to the secondary electrolysis effluent to adjust the pH to 7-10. After standing for 1-2 hours, a precipitant is added to carry out a precipitation reaction for 20-40 minutes. After the reaction, the effluent is refluxed at a reflux ratio of 100-200% to the point before the acidic substances are added to adjust the pH value in step (3). The remaining effluent enters a deep treatment device.

[0033] In the present invention, the waste alkali liquid of amine liquid regeneration is strongly alkaline, with a pH of about 13.0-13.5, and the main pollutants are high-concentration sulfides, COD and N-methyldiethanolamine. The pH of the external drainage of the monomer recovery unit of the nitrile rubber production device is about 9-10, and the main pollutants are residual acrylonitrile after monomer recovery and latex substances discharged during the stripping process.

[0034] According to the treatment method of the present invention, in some embodiments, in step (1), the time for the homogenization adjustment of the amine regeneration waste alkali solution and the time for the homogenization adjustment of the external drainage of the monomer recovery unit of the nitrile rubber production device are both 0.5-8h. It can be understood that the homogenization adjustment time can be any specific value of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h or any value within the range of 0.5-8h. Homogenization adjustment is a mixing process, the purpose of which is to balance the changes in water quality, water volume, etc. of the amine regeneration waste alkali solution and the external drainage of the monomer recovery unit of the nitrile rubber production device, so that the intake of the two is evenly distributed. In the present invention, the homogenization adjustment can be carried out in a homogenization tank. The present invention has no special restrictions on the homogenization tank, which can be a conventional homogenization tank in the art.

[0035] According to the treatment method of the present invention, in some embodiments, in step (1), the waste alkali solution from amine liquid regeneration is subjected to pressure treatment after a homogenization adjustment, and specifically, the waste alkali solution from amine liquid regeneration is subjected to pressure treatment by passing through a pressurized gas dissolving tank, and the pressure in the pressurized gas dissolving tank is 300-550 kPa. After the pressurized treatment of the present invention, the waste alkali solution from amine liquid regeneration not only has a flotation effect after entering the electrolytic reactor, but also increases the oxygen concentration of the solution in the water, making it easier for the anode to precipitate oxygen, which is beneficial to the electrolytic reaction to generate highly oxidizing hydroxyl radicals.

[0036] In some embodiments, in step (2), the primary electrolysis reactor includes a primary electrolysis reactor cavity, which is formed by wrapping a shell and is provided with a plurality of electrolysis reaction chambers distributed in a honeycomb shape, each electrolysis reaction chamber is provided with a primary electrolysis anode, a primary electrolysis cathode and a water distribution plate located at the bottom, the primary electrolysis anode is located at the center of the electrolysis reaction chamber, and is 3-10 cm away from the primary electrolysis cathode; the surface of the primary electrolysis anode is coated with a double-layer corrosion-resistant mesh, and the bottom of the primary electrolysis anode is connected to a rotating motor, and the rotating motor can drive the double-layer corrosion-resistant mesh coated on the surface of the primary electrolysis anode to rotate.

[0037] Furthermore, in some specific embodiments, the primary electrolytic reactor cavity is formed by wrapping a shell, the shell is a stainless steel plate with an inner lining, and the inner lining is made of an insulating and anti-corrosion material. The shell of the present invention can further increase the robustness of the primary electrolytic reactor.

[0038] Further, in some specific embodiments, the cross-section of each electrolytic reaction chamber is preferably hexagonal.

[0039] In some embodiments, in step (2), a plurality of small holes are provided on the water distribution plate, the diameter of the small holes is 2-10 mm, and the small holes are evenly distributed on the entire distribution plate.

[0040] In some embodiments, the primary electrolysis anode is any one of a graphite electrode and an activated carbon electrode. Furthermore, the primary electrolysis anode can be an anode rod with a diameter of 8-12 mm, which is installed in the center of each electrolysis reaction chamber, 3-10 cm away from the primary electrolysis cathode, preferably 5-8 cm; the primary electrolysis cathode is a ruthenium-coated stainless steel electrode, and the cathode material of the present invention can enhance the corrosion resistance of the electrode.

[0041] In some embodiments, in step (2), the double-layer corrosion-resistant mesh covering the surface of the primary electrolysis anode is any one of a 316L stainless steel mesh and a nylon mesh. The present invention connects a rotating motor to the bottom of the primary electrolysis anode. After the electrolysis starts, the double-layer corrosion-resistant mesh moves in the reverse direction driven by the rotating motor to avoid S in the water. 2- The electrolytic oxidation generates sulfur and agglomerated rubber particles which adhere to the anode and passivate the anode.

[0042] In some embodiments, in step (2), a suspended matter collector is disposed above each electrolysis reaction chamber, and the suspended matter collector is capable of collecting suspended matter on the water surface in the electrolysis reaction chamber and transporting it to a solid-liquid separation device located outside the primary electrolysis reactor.

[0043] The present invention has no specific restrictions on the solid-liquid separation device, and conventional equipment and facilities with solid-liquid separation functions in the art can be used, and can be selected according to the site and water quality conditions in specific applications. For example, the solid-liquid separation device may include a centrifugal separator, a laminated filter, and a sand filter.

[0044] Further, in some specific embodiments, when the primary electrolytic reactor is working, the operating voltage is 5-25V, preferably 10-22V; the current density is 10-30mA / cm 2 , preferably 12-28 mA / cm 2 ; The reaction temperature is 30-50°C, preferably 35-45°C; the electrolysis reaction time is 1-3.5h, preferably 1.5-3.0h.

[0045] The present invention uses a special structure of the first-stage electrolytic reactor to perform a first-stage electrolytic reaction on the mixed influent water, so as to treat S 2- Controlled oxidation is performed to generate sulfur and quickly separate it from water, effectively preventing sulfur from dissolving in an alkaline environment to form polysulfides or being deeply oxidized to SO3 2- 、SO4 2- and thiosulfate and other by-products. In the primary electrolysis reaction, the high concentration of S in the amine solution regeneration waste alkali 2- Oxidation reaction occurs at the anode to generate elemental sulfur; hydrogen is generated at the cathode, diffuses from the electrode surface into the solution, and precipitates in the form of bubbles after reaching saturation. Under the action of the electric field, the latex particles with negative charge move toward the anode and gather, condensing to form large rubber particles, which envelop elemental sulfur with an average diameter of only about 61.7nm, making its particle size increase to 1-3mm, and concentrate near the anode electrode rod and adhere to the double-layer corrosion-resistant net covered on the surface of the anode rod. The double-layer corrosion-resistant net moves in reverse under the drive of the rotating motor to peel off the adhered particles; in addition, a variety of generation aids are added during the production of nitrile rubber, among which substances with surfactant effects can be adsorbed on the electrode surface, which can make the deposition of elemental sulfur at the anode loose and easy to remove. In addition, during the electrolysis reaction in the primary electrolysis reactor of the present invention, the generated hydrogen and the bubbles brought in by pressure during water inlet adhere to the surface of the suspended particle pollutants, causing the pollutants to float to the top of the reactor. A suspended matter collector floating above the water surface is installed above each electrolysis reaction chamber to promptly collect bubbles and suspended matter generated during the electrolysis process and transport them to the solid-liquid separation device located outside the primary electrolysis reactor. The wastewater after solid-liquid separation returns to the primary electrolysis reactor for further desulfurization treatment until the sulfide concentration is detected to be less than 30 mg / L.

[0046] The invention designs a two-stage electrolysis reaction process of primary electrolysis and secondary electrolysis. On the one hand, acrylonitrile remaining in the external drainage of a monomer recovery unit from a nitrile rubber production device can be hydrolyzed into acrylamide and acrylic acid under the action of an alkaline environment and an electric field, thereby avoiding the overflow of highly toxic HCN in subsequent advanced oxidation treatment. On the other hand, in the primary electrolysis reactor, N-methyldiethanolamine, rubber production additives and the like are oxidatively degraded to generate more small molecular organic matter, such as N-methyldiethanolamine generating methyl monoethanolamine, or further oxidizing into aminoacetic acid. During the electrolysis process, pH value slowly decreases from strong alkalinity to 6-9, and the removal rate of sulfide and latex is greater than 95%.

[0047] Furthermore, in some specific embodiments, in the first-level electrolysis reaction stage of step (2), multiple groups of first-level electrolysis reactors can be connected in parallel according to the water volume, and "multiple on and one standby" can work alternately. The "multiple on and one standby" means that one or two of the equipment are in the drainage state, and the remaining equipment is in the electrolysis sewage treatment state. When the monitoring value of sulfide in the mixed influent is less than 30 mg / L, the sewage is discharged from the drainage port at the bottom of the reactor into the homogenization tank.

[0048] In some embodiments, in step (3), an acidic substance is first added to the primary electrolyzed water to adjust the pH to 3-6, preferably 3.5-5.5; the acidic substance may be hydrochloric acid, and then a secondary homogenization adjustment is performed. The time for the secondary homogenization adjustment is 0.5-3h. It is understood that the homogenization adjustment time may be any specific value of 0.5h, 1h, 1.5h, 2h, 2.5h, 3h or any value within the range of 0.5-3h.

[0049] In some specific embodiments, the secondary homogenization adjustment can be performed in a homogenization tank. The present invention has no special restrictions on the homogenization tank, which can be a conventional homogenization tank in the art. Specifically, the wastewater after desulfurization and latex removal is transported to the homogenization tank via a pipeline, and the acidic substance is added on the transport pipeline to adjust the pH to 3-6, preferably 3.5-5.5, to create conditions for secondary electrolysis under acidic conditions. Furthermore, in addition to adding acidic substances, the pH is also adjusted by the wastewater from the chemical precipitation reflux in step (5). In the present invention, the residual S in the water is adjusted by secondary homogenization. 2- H2S gas is generated under acidic conditions, and then introduced into the amine liquid regeneration waste alkali liquid storage tank, where it is absorbed by the alkali liquid and the first-level electrolytic desulfurization is repeated to completely eliminate S 2- Impact on subsequent reactions.

[0050] In some embodiments, in step (4), the secondary electrolysis reactor comprises a secondary electrolysis reactor cavity, a water inlet pipe and a water outlet pipe, a vertically parallel anode plate and a cathode plate are arranged in the middle of the secondary electrolysis reactor cavity, respectively connected to the positive and negative poles of the power supply, the spacing between the anode plate and the cathode plate is 3-10 cm, preferably 4-9 cm, and porous iron-carbon fillers are filled between the plates; one end of the water inlet pipe is connected to the secondary homogenization adjustment water outlet, and the other end is inserted in the middle of the iron-carbon filler; an ultrasonic transducer is arranged at the outer bottom of the secondary electrolysis reactor cavity, and the ultrasonic transducer is connected to the ultrasonic generator; an overflow weir is arranged at the inner upper part of the secondary electrolysis reactor cavity, and the overflow weir is connected to the secondary electrolysis reactor water outlet pipe.

[0051] In some embodiments, in step (4), the anode plate and the cathode plate are both made of Ti-coated or ruthenium-coated 316L stainless steel mesh.

[0052] In some specific embodiments, the iron-carbon filler is a filter material containing carbon and iron components, and is a solid particle with a certain strength and hardness. The present invention has no specific restrictions on the specific brand of the iron-carbon filler, and conventional commercial products in the field can be used, preferably high-temperature sintered multi-catalytic oxidation iron-carbon filler, including but not limited to this type of filler.

[0053] In some specific embodiments, an ultrasonic transducer is attached to the outer bottom of the secondary electrolysis reactor cavity. The present invention has no specific restrictions on the structure of the ultrasonic transducer and the ultrasonic generator, and conventional ultrasonic transducers and ultrasonic generators in the art can be used.

[0054] In some embodiments, the ultrasonic frequency is 20-80kHz, preferably 25-75kHz; the ultrasonic power is 50-500w.

[0055] Furthermore, in some specific embodiments, when the secondary electrolysis reactor is in operation, the operating voltage is 15-40V, preferably 12-38V; the current density is 40-90mA / cm 2 , preferably 45-85mA / cm 2 The reaction temperature is 40-50°C and the reaction time is 1-2.5h. In the present invention, the secondary electrolysis effluent is further discharged from the overflow weir at the upper part of the secondary electrolysis reactor and enters the subsequent chemical precipitation treatment.

[0056] In some embodiments, a plurality of water inlets are provided at one end of the water inlet pipe of the secondary electrolysis reactor inserted into the middle of the iron-carbon filler, the diameter of the water inlet is 5-25 mm, and the number of the water inlets is 20-200.

[0057] The present invention uses a special structure of the secondary electrolytic reactor to treat the sewage by secondary electrolytic reaction, adopts the cathode electrolytic Fenton method, and cooperates with the oscillation, fractionation, cavitation and cavitation effect of ultrasound to make the refractory organic matter in the waste alkali solution of amine liquid regeneration and the external drainage of the monomer recovery unit of the nitrile rubber production device undergo advanced oxidation reaction, and carry out COD reduction treatment, while delaying the caking of iron-carbon fillers and electrode plates. Its basic principle is: in the secondary electrolytic reactor, O2 is reduced to H2O2 at the cathode and reacts with Fe 2+ Fenton reaction occurs to generate ·OH; refractory organic matter is oxidized by ·OH to CO2 and H2O, or small molecular organic matter, such as oxalic acid, ethylene glycol, methanol, aminoacetic acid, acrylic acid, etc. These substances have good biodegradability, and the BOD / COD value of sewage is significantly improved. In the subsequent biological denitrification stage, sufficient carbon source can be provided for microorganisms, reducing the dosage of exogenous denitrification carbon source. In addition, the special structure of the secondary electrolytic reactor of the present invention can allow sewage to enter the iron-carbon filler through the water inlet of the water inlet pipe and be evenly distributed in the secondary electrolytic reactor. The Fe in the iron-carbon filler is 2+ It dissolves in water and provides a catalyst for Fenton oxidation, so there is no need to add chemical reagents such as ferrous sulfate and H2O2. The two-stage electrolysis treatment designed by the present invention can shorten the Fenton reaction time and reduce the operating cost. The reaction time for COD removal rate>95% is reduced from 3-4h to 1-2.5h, and the ammonia nitrogen concentration of the effluent is significantly increased after the nitrogen-containing organic matter is oxidized.

[0058] In some embodiments, in step (5), the precipitant is MgCl2·6H2O and Na2HPO4·6H2O, wherein the molar ratio of the elements is n(N):n(P):n(Mg)=1:0.9-1:1-1.3.

[0059] The present invention can remove ammonia nitrogen from water by the chemical precipitation step (5). The specific removal principle is as follows: after adding alkaline substances such as NaOH to the sewage to adjust the pH, Fe(OH)3 precipitation is first generated. After standing for 1-2 hours, a precipitant is added to the water to react with NH4 + The reaction generates a white precipitate of MgNH4O4·6H2O (MAP for short), thereby achieving the removal of ammonia nitrogen in water. The precipitate MAP produced in the chemical precipitation step can further enter the MAP regeneration unit to generate magnesium hydrogen phosphate for recycling after washing, drying and pyrolysis.

[0060] In the present invention, in step (5), the precipitant and NH4 in water +After that, the pH value of the water will drop rapidly, affecting the production of MAP. In order to stabilize the pH value at 9-9.5, the precipitation reaction time of the sewage is controlled to be 20-40 minutes, and the effluent after the reaction is further refluxed to step (3) before adding the acidic substance to adjust the pH value, and the pH value of the primary electrolysis effluent is adjusted together with the acidic substance.

[0061] In the present invention, the sewage treated by the method of the present invention can be further treated in an activated sludge adsorption tank and a biochemical treatment unit for subsequent deep treatment, and the sewage can be discharged up to standard after treatment. The present invention has no specific restrictions on the activated sludge adsorption tank and the biochemical treatment unit, and conventional devices and processes in the art can be used.

[0062] The present invention will be described in detail below by way of examples. It should be understood that the following examples are only used to further explain and illustrate the content of the present invention by way of example, and are not intended to limit the present invention.

[0063] In the present invention, the testing methods of various performance parameters in the embodiments and comparative examples are as follows: Conductivity: Tested in accordance with GB / T6682-2008; Chemical oxygen demand COD: tested according to HJ828-2017 standard; Biochemical oxygen demand BOD: tested according to HJ505-2009 standard; Total nitrogen content: tested according to BSEN12260-2003 standard; Ammonia nitrogen concentration: tested according to HJ / T195-2005 standard; Sulfide concentration: tested according to HJ / T60-2000 standard.

[0064] Reference Figure 2 and Figure 3A primary electrolytic reactor comprises a primary electrolytic reactor cavity 4-8, which is formed by wrapping a shell 4-7, and is provided with a plurality of electrolytic reaction chambers 4-10 distributed in a honeycomb shape, each electrolytic reaction chamber 4-10 is provided with a primary electrolytic anode 4-1, a primary electrolytic cathode 4-2 and a water distribution plate 4-3 located at the bottom, the primary electrolytic anode 4-1 is located at the center of the electrolytic reaction chamber 4-10, and is 3-10cm away from the primary electrolytic cathode 4-2; the surface of the primary electrolytic anode 4-1 is coated with a double-layer corrosion-resistant mesh, and the bottom of the primary electrolytic anode 4-1 is connected to a rotating motor 4-1, and the rotating motor 4-4 can drive the double-layer corrosion-resistant mesh coated on the surface of the primary electrolytic anode to rotate. A suspended matter collector 4-6 is arranged above each electrolytic reaction chamber 4-10, and the suspended matter collector 4-6 can collect suspended matter on the water surface in the electrolytic reaction chamber 4-10 and transport it to a solid-liquid separation device located outside the primary electrolytic reactor. The water distribution plate is provided with a plurality of small holes 4-9, the diameter of the small holes is 2-10 mm, and the small holes are evenly distributed on the entire distribution plate.

[0065] Reference Figure 4 and Figure 5 A secondary electrolytic reactor comprises a secondary electrolytic reactor cavity 6-3, an inlet pipe 6-5 and an outlet pipe 6-6, wherein a vertically parallel anode plate 6-1 and a cathode plate 6-2 are arranged in the middle of the secondary electrolytic reactor cavity 6-3, respectively connected to the positive and negative electrodes of the secondary electrolytic reaction power supply 6-11, the spacing between the anode plate 6-1 and the cathode plate 6-2 is 3-10 cm, and a porous iron-carbon filler 6-8 is filled between the plates; one end of the inlet pipe 6-6 is connected to the secondary homogenization regulating water outlet, and the other end is inserted in the middle of the iron-carbon filler 6-8; an ultrasonic transducer 6-9 is pasted on the outer bottom of the secondary electrolytic reactor cavity 6-3, and the ultrasonic transducer 6-9 is connected to the ultrasonic generator 6-10; an overflow weir 6-7 is arranged on the inner upper part of the secondary electrolytic reactor cavity 6-3, and the overflow weir 6-7 is connected to the outlet pipe 6-6 of the secondary electrolytic reactor.

[0066] Example 1 A pretreatment process for waste alkali solution of amine solution regeneration, such as Figure 1 As shown. Specifically including the steps: (1) Primary homogenization adjustment: 2m2 of waste alkali solution from amine liquid regeneration of sulfur recovery unit 3 / h and 2m of external drainage from the monomer recovery unit of the nitrile rubber production device 3 / h enters the first homogenization tank and the second homogenization tank for homogenization adjustment respectively. The homogenization adjustment time is 1h. The water from the first homogenization tank enters the pressurized gas dissolving tank 3 for pressurization treatment. The pressure of the pressurized gas dissolving tank 3 is 300-550kPa. At this time, the first valve and the second valve are in an open state, and the two sewage are mixed in a volume ratio of 1:1. The water quality of the mixed water is: pH value: 12.5, conductivity: 35000μS.cm -1 , COD: 44500mg / L; total nitrogen: 2890mg / L, sulfide concentration: 3360mg / L.

[0067] (2) Primary electrolysis: The mixed influent enters the primary electrolytic reactor 4 through the water distribution plate 4-3. After reaching the predetermined water level, the first valve and the second valve are closed, the fourth valve and the fifth valve are opened, and the sewage circulates between the electrolytic reactor 4 and the solid-liquid separation device 9. The electrolytic reactor uses a graphite electrode as the anode and a ruthenium-coated stainless steel electrode as the cathode. It is powered by a pulse power supply with an operating voltage of 22V and an electrolytic reaction current density of 28mA / cm 2 , reaction temperature 50°C, electrolysis reaction time 3.0h. The rotating motor 4-4 drives the double-layer stainless steel mesh wrapped on the graphite electrode to rotate, causing the latex and S attached to the anode to fall off, and float to the water surface driven by the bubbles generated by electrolysis, and are sucked out by the negative pressure generated by the suspended matter collector 4-6 floating on the water surface, and enter the solid-liquid separation device 9. After centrifugal separation, the suspended matter in the water is intercepted, and the reflux liquid enters through the water distribution plate at the bottom of the electrolysis reaction chamber again for cyclic electrolysis. Until the monitor 11 detects that the sulfide concentration is 29mg / L, the third valve is opened. After testing, the effluent water quality is: pH value: 8.9, conductivity: 33800μS·cm -1 , COD: 35270mg / L, COD removal rate: 20.7%, total nitrogen: 2680mg / L, total nitrogen removal rate: 7.3%, ammonia nitrogen concentration: 11.7mg / L, sulfide concentration: 30mg / L.

[0068] (3) Secondary homogenization adjustment: Add HCl to the sewage delivery pipeline, use air blowing to stir, adjust the pH value to 3.5, and the residual S 2- Under acidic conditions, H2S gas is generated and blown out of the water. A waste gas collector is set on the top of the homogenization tank to introduce the H2S gas into the first homogenization tank for alkaline solution absorption.

[0069] (4) Secondary electrolysis: The sewage flows into the iron-carbon filler area from the water inlet pipe located in the center of the secondary electrolysis reactor 6-1 for electrolysis reaction. The anode and cathode of the secondary electrolysis reactor are both made of Ti-coated 316L stainless steel mesh. The working voltage is 38V and the electrolysis reaction current density is 85mA / cm 2, reaction temperature 50℃, electrolysis reaction time 2.5h. Ultrasonic working frequency 80kHz, power 300w. After testing, the water quality of the secondary electrolysis water is: pH value: 3.5, conductivity: 33200μS·cm -1 , COD: 1520mg / L, COD removal rate: 95.7%, total nitrogen: 1520mg / L, total nitrogen removal rate: 43.3%, ammonia nitrogen concentration: 1216mg / L, sulfide concentration: 0mg / L.

[0070] (5) Chemical precipitation: NaOH was added to the water pipeline to adjust the pH value to 9. The sewage flowed to the chemical precipitation unit and stood for 1.5 hours. MgCl2·6H2O and Na2HPO4·6H2O were added to the supernatant, n(N):n(P):n(Mg)=1:0.9:1.3. The reaction lasted for 40 minutes. The effluent was refluxed at a reflux ratio of 200% before the acid was added for secondary homogenization. After testing, the effluent quality was as follows: pH value: 8, COD: 1109 mg / L, total nitrogen: 405 mg / L, total nitrogen removal rate: 73.4%, ammonia nitrogen concentration: 145 mg / L, ammonia nitrogen removal rate: 88.1%.

[0071] The effluent from the chemical precipitation unit then flows to the sludge adsorption unit 8 to complete the adsorption of soluble pollutants and large suspended impurities by activated sludge. At this time, the BOD / COD value of the sewage reaches 0.61, creating good conditions for subsequent biochemical treatment.

[0072] Example 2 A pretreatment process for waste alkali solution of amine solution regeneration, such as Figure 1 As shown. Specifically including the steps: (1) Primary homogenization adjustment: 2m2 of waste alkali solution from amine liquid regeneration of sulfur recovery unit 3 / h and 6m of external drainage from the monomer recovery unit of the nitrile rubber production unit 3 / h enters the first homogenization tank and the second homogenization tank for homogenization adjustment respectively. The homogenization adjustment time is 5h. The water from the first homogenization tank enters the pressurized gas dissolving tank 3 for pressurization treatment. The pressure of the pressurized gas dissolving tank 3 is 300-550kPa. At this time, the first valve and the second valve are in an open state, and the two sewage are mixed in a volume ratio of 1:3. The water quality of the mixed water is: pH value: 11.2, conductivity: 12600μS·cm -1 , COD: 24033mg / L, total nitrogen: 1550mg / L, sulfide concentration: 1058mg / L.

[0073] (2) Primary electrolysis: The mixed influent enters the primary electrolytic reactor 4 through the water distribution plate 4-3. After reaching the predetermined water level, the first valve and the second valve are closed, the fourth valve and the fifth valve are opened, and the sewage circulates between the electrolytic reactor 4 and the solid-liquid separation device 9. The electrolytic reactor uses a graphite electrode as the anode and a ruthenium-coated stainless steel electrode as the cathode. It is powered by a pulse power supply, has an operating voltage of 16V, and an electrolytic reaction current density of 18mA / cm 2 , reaction temperature 45°C, electrolysis reaction time 2.5h. The rotating motor 4-4 drives the double-layer stainless steel mesh wrapped on the graphite electrode to rotate, causing the latex and S attached to the anode to fall off, and float to the water surface driven by the bubbles generated by electrolysis, and are sucked out by the negative pressure generated by the suspended matter collector 4-6 floating on the water surface, and enter the solid-liquid separation device 9. After centrifugal separation, the suspended matter in the water is intercepted, and the reflux liquid enters again through the water distribution plate at the bottom of the electrolysis reaction chamber for cyclic electrolysis. Until the monitor 11 detects that the sulfide concentration is 25mg / L, the third valve is opened. After testing, the effluent water quality is: pH value: 8.1, conductivity: 115900μS·cm -1 , COD: 16904mg / L, COD removal rate: 29.7%, total nitrogen: 1380mg / L, total nitrogen removal rate: 11.0%, ammonia nitrogen concentration: 23.8mg / L, sulfide concentration: 29mg / L.

[0074] (3) Secondary homogenization adjustment: Add HCl to the sewage delivery pipeline, use air blowing to stir, adjust the pH value to 3.5, and the residual S 2- Under acidic conditions, H2S gas is generated and blown out of the water. A waste gas collector is set on the top of the homogenization tank to introduce the H2S gas into the first homogenization tank for alkaline solution absorption.

[0075] (4) Secondary electrolysis: The sewage flows into the iron-carbon filler area from the water inlet pipe located in the center of the secondary electrolysis reactor 6-1 for electrolysis reaction. The anode and cathode of the secondary electrolysis reactor are both made of Ti-coated 316L stainless steel mesh. The working voltage is 25V and the electrolysis reaction current density is 55mA / cm 2 , reaction temperature 45℃, electrolysis reaction time 2h. Ultrasonic working frequency 60kHz, power 300w. After testing, the water quality of the secondary electrolysis water is: pH value: 3.2, conductivity: 12000μS·cm -1 , COD: 684mg / L, COD removal rate: 96.0%, total nitrogen: 786mg / L, total nitrogen removal rate: 43.0%, ammonia nitrogen concentration: 589.5mg / L, sulfide concentration: 0mg / L.

[0076] (5) Chemical precipitation: NaOH was added to the water pipeline to adjust the pH value to 9.5. The sewage flowed to the chemical precipitation unit and stood for 1.5 hours. MgCl2·6H2O and Na2HPO4·6H2O were added to the supernatant, n(N):n(P):n(Mg)=1:1:1. The reaction lasted for 40 minutes. The effluent was refluxed at a reflux ratio of 150% before the acid was added for secondary homogenization. After testing, the effluent quality was as follows: pH value 8.5, COD: 532 mg / L, total nitrogen: 230 mg / L, total nitrogen removal rate: 70.7%, ammonia nitrogen concentration: 93 mg / L, ammonia nitrogen removal rate: 84.2%.

[0077] The effluent from the chemical precipitation unit then flows to the sludge adsorption unit 8 to complete the adsorption of soluble pollutants and large suspended impurities by activated sludge. At this time, the BOD / COD value of the sewage reaches 0.63, creating good conditions for subsequent biochemical treatment.

[0078] Example 3 A pretreatment process for waste alkali solution of amine solution regeneration, such as Figure 1 As shown. Specifically including the steps: (1) Primary homogenization adjustment: 2m2 of waste alkali solution from amine liquid regeneration of sulfur recovery unit 3 / h and 10m of external drainage from the monomer recovery unit of the nitrile rubber production unit 3 / h enters the first homogenization tank and the second homogenization tank for homogenization adjustment respectively. The homogenization adjustment time is 8h. The water from the first homogenization tank enters the pressurized gas dissolving tank 3 for pressurization treatment. The pressure of the pressurized gas dissolving tank 3 is 300-550kPa. At this time, the first valve and the second valve are in an open state, and the two sewage are mixed at a volume ratio of 1:3. The water quality of the mixed water is: pH value: 10.5, conductivity: 10000μS·cm -1 , COD: 14520mg / L, total nitrogen: 1150mg / L, sulfide concentration: 980mg / L.

[0079] (2) Primary electrolysis: The mixed influent enters the primary electrolytic reactor 4 through the water distribution plate 4-3. After reaching the predetermined water level, the first valve and the second valve are closed, the fourth valve and the fifth valve are opened, and the sewage circulates between the electrolytic reactor 4 and the solid-liquid separation device 9. The electrolytic reactor uses a graphite electrode as the anode and a ruthenium-coated stainless steel electrode as the cathode. It is powered by a pulse power supply, has an operating voltage of 10V, and an electrolytic reaction current density of 12mA / cm 2, reaction temperature 40°C, electrolysis reaction time 1.8h. The rotating motor 4-4 drives the double-layer stainless steel mesh wrapped on the graphite electrode to rotate, causing the latex and S attached to the anode to fall off, and float to the water surface driven by the bubbles generated by electrolysis, and are sucked out by the negative pressure generated by the suspended matter collector 4-6 floating on the water surface, and enter the solid-liquid separation device 9. After centrifugal separation, the suspended matter in the water is intercepted, and the reflux liquid enters again through the water distribution plate at the bottom of the electrolysis reaction chamber for cyclic electrolysis. Until the monitor 11 detects that the sulfide concentration is 25mg / L, the third valve is opened. After testing, the effluent water quality is: pH value: 8.1, conductivity: 9870μS·cm -1 , COD: 11250mg / L, COD removal rate: 22.5%, total nitrogen: 988mg / L, total nitrogen removal rate: 14.0%, ammonia nitrogen concentration: 20.8mg / L, sulfide concentration: 25mg / L.

[0080] (3) Secondary homogenization adjustment: Add HCl to the sewage delivery pipeline, use air blowing to stir, adjust the pH value to 3.5, and the residual S 2- Under acidic conditions, H2S gas is generated and blown out of the water. A waste gas collector is set on the top of the homogenization tank to introduce the H2S gas into the first homogenization tank for alkaline solution absorption.

[0081] (4) Secondary electrolysis: The sewage flows into the iron-carbon filler area from the water inlet pipe located in the center of the secondary electrolysis reactor 6-1 for electrolysis reaction. The anode and cathode of the secondary electrolysis reactor are both made of ruthenium-coated 316L stainless steel mesh. The working voltage is 16V and the electrolysis reaction current density is 45mA / cm 2 , reaction temperature 45℃, electrolysis reaction time 1.5h. Ultrasonic working frequency 20kHz, power 500w. After testing, the water quality of the secondary electrolysis water is: pH 3.0, conductivity: 9663μS·cm -1 , COD: 496mg / L, COD removal rate: 95.6%, total nitrogen: 528mg / L, total nitrogen removal rate: 46.5%, ammonia nitrogen concentration: 438.2mg / L, sulfide concentration: 0mg / L.

[0082] (5) Chemical precipitation: NaOH was added to the water pipeline to adjust the pH value to 8.0. The sewage flowed to the chemical precipitation unit and stood for 1.5 hours. MgCl2·6H2O and Na2HPO4·6H2O were added to the supernatant, n(N):n(P):n(Mg)=1:1:1. The reaction lasted for 40 minutes. The effluent was refluxed at a reflux ratio of 150% before the acid was added for secondary homogenization. After testing, the effluent quality was as follows: pH value 8.5, COD: 360 mg / L, total nitrogen: 151 mg / L, total nitrogen removal rate: 71.4%, ammonia nitrogen concentration: 85 mg / L, ammonia nitrogen removal rate: 80.6%.

[0083] The effluent from the chemical precipitation unit then flows to the sludge adsorption unit 8 to complete the adsorption of soluble pollutants and large suspended impurities by activated sludge. At this time, the BOD / COD value of the sewage reaches 0.65, creating good conditions for subsequent biochemical treatment.

[0084] Comparative Example 1 The pretreatment process of the amine solution regeneration waste alkali solution in Comparative Example 1 is the same as that in Example 1, except that the surface of the primary electrolysis anode of the primary electrolysis reactor in Comparative Example 1 is not coated with a double-layer corrosion-resistant mesh, and the bottom of the primary electrolysis anode is not connected to a rotating motor. After 2 hours of use, the surface of the anode electrolysis rod is covered with elemental S produced by electrolysis, resulting in passivation of the electrode plate. After testing, the sulfide concentration in the effluent water rapidly increased to 2512 mg / L.

[0085] Comparative Example 2 The pretreatment process of the amine solution regeneration waste alkali solution in Comparative Example 2 is the same as that in Example 1, except that there is no primary electrolysis step in Comparative Example 2. After testing, the COD of the secondary electrolysis effluent is 10591 mg / L, and the COD removal rate is 76.2%.

[0086] It can be seen from Example 1 and Comparative Example 1 that in the embodiment of the present invention, by setting a rotating motor in the primary electrolysis reactor to drive the double-layer corrosion-resistant mesh coated on the surface of the primary electrolysis anode to rotate, the sulfide in the wastewater can be better removed. It can be seen from Example 1 and Comparative Example 2 that in the embodiment of the present invention, by setting a special two-stage electrolysis treatment, the COD removal rate of the wastewater under the same time is significantly improved, and the operating cost is reduced.

[0087] It can be seen that the present invention achieves the purification effects of wastewater sulfur removal, nitrile removal, COD reduction and nitrogen removal by sequentially subjecting two highly toxic and difficult-to-degrade mixed sewage, namely, amine liquid regeneration waste alkali liquid and nitrile rubber monomer recovery drainage, to "two-stage electrolysis + chemical precipitation", thereby achieving the purpose of "treating waste with waste" and co-degrading pollutants. The BOD / COD value of the treated sewage is greater than 0.6, and the biodegradability is significantly improved.

[0088] Obviously, the above embodiments of the present invention are only examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made on the basis of the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the protection scope of the present invention.

Claims

1. A pretreatment process for waste alkali liquor regeneration from amine liquor, characterized in that: The steps include: (1) Primary homogenization and adjustment: The waste alkali liquor from amine regeneration is subjected to pressure treatment after primary homogenization and adjustment to obtain the treated waste alkali liquor from amine regeneration; the waste water from the monomer recovery unit of the nitrile rubber production device is subjected to primary homogenization and adjustment to obtain the treated waste water; (2) Primary electrolysis: The treated amine solution regeneration waste alkali solution and the treated external drainage are mixed in a volume ratio of 1:1-1:5 and enter the primary electrolysis reactor for primary electrolysis reaction. The working voltage of the primary electrolysis reactor is 5-25V and the current density is 10-30mA / cm 2 , the reaction temperature is 30-50°C, the reaction time is 1-3.5h, and primary electrolysis water is obtained; (3) Secondary homogenization adjustment: Acidic substances are added to the primary electrolyzed water to adjust the pH to 3-6, and secondary homogenization adjustment is performed; (4) Secondary electrolysis: The effluent from step (3) enters a secondary electrolysis reactor for secondary electrolysis reaction. The operating voltage of the secondary electrolysis reactor is 15-40V and the current density is 40-90mA / cm 2 , the reaction temperature is 40-50°C, the reaction time is 1-2.5h, and secondary electrolysis water is obtained; (5) Chemical precipitation: alkaline substances are added to the secondary electrolysis effluent to adjust the pH to 7-10. After standing for 1-2 hours, a precipitant is added to carry out a precipitation reaction for 20-40 minutes. After the reaction, the effluent is refluxed at a reflux ratio of 100-200% to the point before the acidic substances are added to adjust the pH value in step (3). The remaining effluent enters a deep treatment device.

2. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 1, characterized in that: In step (2), the primary electrolysis reactor comprises a primary electrolysis reactor cavity, which is formed by wrapping a shell and is provided with a plurality of electrolysis reaction chambers distributed in a honeycomb shape. Each electrolysis reaction chamber is provided with a primary electrolysis anode, a primary electrolysis cathode and a water distribution plate located at the bottom. The primary electrolysis anode is located at the center of the electrolysis reaction chamber and is 3-10 cm away from the primary electrolysis cathode. The surface of the primary electrolysis anode is coated with a double-layer corrosion-resistant mesh, and the bottom of the primary electrolysis anode is connected to a rotating motor, and the rotating motor can drive the double-layer corrosion-resistant mesh coated on the surface of the primary electrolysis anode to rotate.

3. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 2, characterized in that: In step (2), a plurality of small holes are provided on the water distribution plate, wherein the diameter of the small holes is 2-10 mm, and the small holes are evenly distributed on the entire distribution plate.

4. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 2, characterized in that: The primary electrolysis anode is any one of a graphite electrode and an activated carbon electrode, and the primary electrolysis cathode is a ruthenium-coated stainless steel electrode.

5. The pretreatment process of waste alkali solution from amine solution regeneration according to claim 2, characterized in that: In step (2), the double-layer corrosion-resistant mesh covering the surface of the primary electrolysis anode is any one of a 316L stainless steel mesh and a nylon mesh.

6. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 2, characterized in that: In step (2), a suspended matter collector is arranged above each electrolytic reaction chamber, and the suspended matter collector is capable of collecting suspended matter on the water surface in the electrolytic reaction chamber and transporting it to a solid-liquid separation device located outside the primary electrolytic reactor.

7. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 1, characterized in that: In step (4), the secondary electrolysis reactor comprises a secondary electrolysis reactor cavity, a water inlet pipe and a water outlet pipe, wherein a vertically parallel anode plate and a cathode plate are arranged in the middle of the secondary electrolysis reactor cavity, respectively connected to the positive and negative poles of a power supply, the spacing between the anode plate and the cathode plate is 3-10 cm, and porous iron-carbon fillers are filled between the plates; one end of the water inlet pipe is connected to the secondary homogenization adjustment water outlet, and the other end is inserted in the middle of the iron-carbon filler; an ultrasonic transducer is arranged at the outer bottom of the secondary electrolysis reactor cavity, and the ultrasonic transducer is connected to an ultrasonic generator; an overflow weir is arranged at the inner upper part of the secondary electrolysis reactor cavity, and the overflow weir is connected to the secondary electrolysis reactor water outlet pipe.

8. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 7, characterized in that: The ultrasonic frequency is 20-80kHz and the ultrasonic power is 50-500w.

9. The pretreatment process for waste alkali solution from amine solution regeneration according to claim 7, characterized in that: One end of the water inlet pipe of the secondary electrolysis reactor inserted into the middle of the iron-carbon filler is provided with a plurality of water inlets, the diameter of the water inlets is 5-25 mm, and the number of the water inlets is 20-200.

10. The pretreatment process of waste alkali solution from amine solution regeneration according to claim 1, characterized in that: In step (5), the precipitant is MgCl2·6H2O and Na2HPO4·6H2O, wherein the molar ratio of the elements is n(N):n(P):n(Mg)=1:0.9-1:1-1.3.

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