CN113003768A - Method for treating polyether polyol production wastewater and equipment for implementing method - Google Patents
Method for treating polyether polyol production wastewater and equipment for implementing method Download PDFInfo
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- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
Abstract
The invention relates to a treatment method of polyether polyol production wastewater and equipment for implementing the treatment method. The treatment method of the polyether polyol production wastewater comprises the following steps: removing solid matters in the polyether polyol production wastewater to obtain liquid wastewater; pretreating the liquid wastewater to obtain a pretreatment solution; mixing the pretreatment solution with an oxidant in the presence of a catalyst and carrying out an oxidation reaction to obtain a reaction product; cooling and depressurizing the reaction product, and then carrying out gas-liquid separation. The method for treating the polyether polyol production wastewater has the advantages of high wastewater treatment efficiency, capability of effectively controlling the reaction, simple and feasible process flow, no need of using a catalyst with overhigh cost, mild reaction conditions, more reasonable flow and more stable reaction.
Description
Technical Field
The invention belongs to the field of industrial wastewater treatment in environmental protection, relates to a treatment method of polyether polyol production wastewater and equipment for implementing the treatment method, and particularly relates to a method for treating high-concentration polyether polyol production wastewater containing toxic organic matters such as acrylonitrile and styrene in a wet oxidation mode.
Background
The wastewater discharged from the polyether polyol production device mainly contains ethylene oxide, propylene oxide, styrene, acrylonitrile, azobisisobutyronitrile and the like, has the characteristics of high COD content, low biodegradability, poor degradability and the like, and is a type of wastewater which is difficult to treat in organic chemical industry. In the prior art, the conventional treatment methods mainly include: anaerobic-aerobic biological treatment, biological activated carbon treatment and the like, and the conventional treatment mode has higher cost and low efficiency. Therefore, the treatment of the organic wastewater difficult to degrade becomes a new challenge in the field of water pollution control, the development of novel and practical environmental protection technology is very necessary, and the exploration of the technology for effectively treating the toxic, harmful and high-concentration organic wastewater becomes the research focus of a plurality of environmental protection technical workers.
At present, the microbiological method is most widely used in the aspect of sewage and wastewater treatment, the metabolic process of microorganisms is utilized to degrade organic matters, and the microbiological method has the advantages of low operation cost, good treatment effect and the like, but for high-concentration toxic organic wastewater containing acrylonitrile, styrene and the like, the biological treatment can be carried out only by pretreatment and dilution, otherwise, a great amount of death of microorganisms in a biological water body can be caused. Even diluted wastewater can affect the life of microorganisms, and the use cost of the biological activated sludge is increased.
The wet oxidation method needs to oxidize dissolved organic matters or reduced inorganic matters in the wastewater under the action of an oxidant at a high temperature (140-315 ℃) and a high pressure (0.5-20 Mpa), so that micromolecular organic matters, water, carbon dioxide and the like can be obtained. Compared with the conventional treatment technology, the wet oxidation method has the advantages of wide application range, high treatment efficiency, high oxidation rate, less secondary pollution and the like, and has better effect on treating high-concentration organic wastewater or salt-containing organic wastewater containing toxic and harmful substances. However, the wet oxidation method has the disadvantages of relatively harsh reaction conditions, high requirements for equipment materials, high investment and the like, and it is difficult to achieve real gas-liquid mixing in the practical application process, so that a high removal rate cannot be achieved under a low temperature and pressure condition, and the technical popularization is limited to a certain extent, so that how to achieve a high removal rate under a mild reaction condition is particularly important.
The Chinese patent CN108101291A combines a deep well oxidation reactor with a solar heating unit, thereby efficiently oxidizing and decomposing organic matters, but the treatment temperature can reach 400 ℃, and the deep well reactor is more difficult to effectively control the reaction when extending into the ground for more than 200 meters, thereby increasing the equipment investment and the treatment cost.
Chinese patent CN105417846A discloses a method for treating polyether polyol process wastewater, which adopts a combination of biological and chemical methods to treat the discharged polyether polyol high-concentration wastewater, and the method has high requirements on wastewater components and complex process flow.
Chinese patent CN109336332A discloses a method for treating organic wastewater with high COD, wherein the organic wastewater is subjected to two catalytic wet oxidations, two biochemical treatments and three solid-liquid separations, and the COD content and nitrogen content both meet the industrial standard, but the process flow is too complicated, the equipment investment is too high, and the operation cost is too high by using transition metals such as rhodium and palladium as catalysts.
Therefore, the research on a method for treating polyether polyol production wastewater with high wastewater treatment efficiency, mild reaction conditions and more reasonable process and equipment for implementing the method become a technical problem to be solved urgently.
Disclosure of Invention
Problems to be solved by the invention
In view of the technical problems in the prior art, for example: the invention firstly provides a method for treating the wastewater generated in polyether polyol production, which is difficult to effectively control the reaction, has higher requirements on wastewater components, excessively complex process flow, excessively high equipment investment and treatment cost, excessively high operating cost and the like due to the adoption of transition metals such as rhodium, palladium and the like as catalysts. The treatment method has the advantages of high wastewater treatment efficiency, mild reaction conditions, more reasonable flow and more stable reaction.
Furthermore, the invention also provides equipment for implementing the treatment method, which can ensure that the treatment method is carried out efficiently and orderly, and has low equipment investment, low treatment cost and low operating cost.
Means for solving the problems
The invention firstly provides a method for treating polyether polyol production wastewater, which comprises the following steps:
removing solid matters in the polyether polyol production wastewater to obtain liquid wastewater;
pretreating the liquid wastewater to obtain a pretreatment solution;
mixing the pretreatment solution with an oxidant in the presence of a catalyst and carrying out an oxidation reaction to obtain a reaction product;
cooling and depressurizing the reaction product, and then carrying out gas-liquid separation.
The processing method according to the present invention, wherein the preprocessing includes: and adjusting the pH value of the liquid wastewater to 0.1-5 by using acid.
The treatment method according to the present invention, wherein the catalyst comprises a metal salt catalyst, wherein a concentration of the metal salt catalyst in the pretreatment liquid is 5ppm to 8000 ppm; and/or
The metal salt comprises one or the combination of more than two of copper salt, iron salt, manganese salt, lead salt, zinc salt and nickel salt.
The treatment method comprises the step of adding oxygen into the polyether polyol production wastewater, wherein the oxygen content in the oxidant is 50-300% of the COD of the polyether polyol production wastewater.
The treatment method of the invention comprises the steps of carrying out oxidation reaction at a reaction temperature of 150-300 ℃, under a reaction pressure of 0.5-8 MPa and for a reaction time of 0.2-10 hours.
According to the treatment method, the temperature of the cooled reaction product is below 60 ℃, and the pressure after pressure reduction is 0.1-6.1 MPa.
The invention also provides equipment for implementing the polyether polyol production wastewater treatment method, which comprises a reaction system, a temperature control system and a pressure maintaining system which are connected.
The equipment comprises a reaction system and a reaction system, wherein the reaction system comprises one or more of a liquid storage tank, a gas supply device, a gas-liquid mixer, an oxidation reactor and a gas-liquid separation tank.
The device according to the invention, wherein the temperature control system comprises an electrical heating medium and/or a heat exchanger.
The apparatus according to the invention, wherein the pressure holding system comprises a pressure pump and/or a pressure relief valve.
ADVANTAGEOUS EFFECTS OF INVENTION
The method for treating the polyether polyol production wastewater has the advantages of high wastewater treatment efficiency, capability of effectively controlling the reaction, simple and feasible process flow, no need of using a catalyst with overhigh cost, mild reaction conditions, more reasonable flow and more stable reaction.
The equipment for implementing the treatment method of the polyether polyol production wastewater is easy to regulate and control, can ensure that the treatment method is carried out efficiently and orderly, and has low equipment investment, low treatment cost and low operation cost.
Drawings
FIG. 1 shows a flow chart of a method for treating wastewater from polyether polyol production according to an embodiment of the present invention.
FIG. 2 shows a flow chart of an apparatus for carrying out the method for treating wastewater from polyether polyol production according to an embodiment of the present invention;
wherein, 1: a liquid storage tank; 2: a pressure pump; 3: a gas-liquid mixer;
4: a heat exchanger; 5: a heater; 6: an oxidation reactor;
7: a pressure reducing valve; 8: a gas-liquid separation tank; 9: a gas supply device.
Detailed Description
The present invention will be described in detail below. The technical features described below are explained based on typical embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:
in the present specification, the numerical range represented by "numerical value a to numerical value B" means a range including the end point numerical value A, B.
In the present specification, "plural" in "plural", and the like means a numerical value of 2 or more unless otherwise specified.
In this specification, the terms "substantially", "substantially" or "substantially" mean an error of less than 5%, or less than 3% or less than 1% as compared to the relevant perfect or theoretical standard.
In the present specification, "%" denotes mass% unless otherwise specified.
In the present specification, the meaning of "may" includes both the meaning of performing a certain process and the meaning of not performing a certain process.
In this specification, "optional" or "optionally" means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
In the present specification, reference to "some particular/preferred embodiments," "other particular/preferred embodiments," "embodiments," and the like, means that a particular element (e.g., feature, structure, property, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and may or may not be present in other embodiments. In addition, it is to be understood that the described elements may be combined in any suitable manner in the various embodiments.
First aspect
The first aspect of the invention provides a method for treating polyether polyol production wastewater, which comprises the following steps:
removing solid matters in the polyether polyol production wastewater to obtain liquid wastewater;
pretreating the liquid wastewater to obtain a pretreatment solution;
mixing the pretreatment solution with an oxidant in the presence of a catalyst and carrying out an oxidation reaction to obtain a reaction product;
cooling and depressurizing the reaction product, and then carrying out gas-liquid separation.
Generally, the COD content of the high-concentration organic wastewater which contains toxic substances such as acrylonitrile and styrene and is difficult to biochemically generate and is contained in the wastewater generated in polyether polyol production is 2000mg/L to 100000 mg/L. The COD removal rate of the wastewater treated by the method can reach more than 85 percent. The method for treating the polyether polyol production wastewater has the advantages of high wastewater treatment efficiency, capability of effectively controlling the reaction, simple and feasible process flow, no need of using a catalyst with overhigh cost, mild reaction conditions, more reasonable flow and more stable reaction.
Since polyether polyol production wastewater contains a large amount of solid matter such as suspended solids and the like, it is necessary to remove the solid matter before the oxidation reaction is carried out. The method for removing solid matter in the present invention is not particularly limited, and a solid-liquid separation method commonly used in the art may be used. For example: centrifugation, filtration, and the like. Preferably, for better removing solid suspended substances, the invention uses a filtration mode to remove solid substances in the polyether polyol production wastewater to obtain liquid wastewater.
Then, in order to make the oxidation reaction proceed better, it is necessary to pretreat the liquid wastewater to obtain a pretreatment liquid. Specifically, in the present invention, the pretreatment is generally to adjust the pH of the liquid wastewater using an acid agent so that the liquid wastewater is acidic. In general, the pH can be adjusted to 0.1 to 5, for example: the pH may be 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, etc. When the pH value of the pretreatment solution is 0.1-5, the oxidation reaction is more favorably carried out. As the acid agent, the present invention is not particularly limited, and there may be mentioned some acid agents commonly used in the art, and in view of the reaction, inorganic acid agents such as: inorganic acids such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and the like.
Further, in the presence of a catalyst, the pretreatment solution and an oxidant are mixed and subjected to oxidation reaction to obtain a reaction product.
Specifically, as for the catalyst, the present invention does not use an excessively expensive catalyst, but uses a general homogeneous catalyst. In some embodiments, the catalyst comprises a low cost metal salt catalyst. And the concentration of the catalyst added to the pretreatment solution is 5ppm to 8000ppm for efficiently performing the oxidation reaction, for example: 100ppm, 200ppm, 300ppm, 400ppm, 500ppm, 600ppm, 700ppm, 800ppm, 900ppm, 1000ppm, 1100ppm, 2000ppm, 3000ppm, 4000ppm, 5000ppm, 6000ppm, 7000ppm, etc.
The metal salt used in the present invention is not particularly limited, and may be any of the inexpensive metal salts commonly used in the art. Specifically, in the present invention, the metal salt may include one or a combination of two or more of copper salt, iron salt, manganese salt, lead salt, zinc salt, and nickel salt. For the anion of the metal salt, any feasible anion may be used. For example, chloride ion, nitrate ion, sulfate ion, etc. may be mentioned.
As the oxidizing agent, the oxidizing agent used in the present invention may contain oxygen. The oxidation reaction of the present invention may be carried out in an oxidation reactor in which the pretreatment liquid is sufficiently mixed with an oxidizing agent, which may be in a gaseous state, such as oxygen or an oxygen-containing component, dissolved in the pretreatment liquid in a pressurized state; or the oxidant is a liquid oxidant and is decomposed at high temperature and high pressure to obtain oxygen. Specifically, according to the depth requirement of treatment, the oxygen content in the oxidant is 50-300% of the COD value of the polyether polyol production wastewater.
In the present invention, the conditions of the oxidation reaction are not particularly limited, and the conditions of the oxidation reaction may be appropriately selected as needed. Specifically, the reaction solution may be heated and then transferred to an oxidation reactor to perform an oxidation reaction. Preferably, in the present invention, the reaction temperature of the oxidation reaction is 150 to 300 ℃, for example: 170 deg.C, 190 deg.C, 210 deg.C, 230 deg.C, 250 deg.C, 270 deg.C, 290 deg.C, etc.; the reaction pressure is 0.5MPa to 8MPa, for example: 1Mpa, 2Mpa, 3Mpa, 4Mpa, 5Mpa, 6Mpa, 7Mpa, 8Mpa, etc.; the reaction time is 0.2h to 10h, for example: 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 6h, 7h, 8h, 9h and the like. When the conditions of the oxidation reaction are within the above range, the organic matter can be more effectively decomposed, so that the COD value can be further reduced.
And cooling and depressurizing the reaction product after the oxidation reaction, and carrying out gas-liquid separation. In particular, the temperature of the reaction product after cooling is below 60 ℃, for example: 10 ℃, 20 ℃, 30 ℃, 40 ℃, 50 ℃ and the like, and the pressure after the pressure reduction is 0.1Mpa to 6.1Mpa, for example: 1MPa, 2MPa, 3MPa, 4MPa, 5MPa, etc.
In some specific embodiments, the gas-liquid separation may be performed in a gas-liquid separation tank; wherein, the gas part after gas-liquid separation is absorbed and purified and then discharged into the air; while the liquid fraction is discharged below the separation tank. The liquid part after processing can directly be discharged, can also directly classify and recycle liquid, and the liquid mixed solution COD clearance that the analysis discharged with the quick tester of COD is more than 85%.
Second aspect of the invention
In a second aspect, the invention provides a device for implementing the polyether polyol production wastewater treatment method in the first aspect, which comprises a reaction system, a temperature control system and a pressure maintaining system which are connected.
In the present invention, the reaction system includes a liquid storage tank 1, a gas supply device 9, a gas-liquid mixer 3, an oxidation reactor 6, and a gas-liquid separation tank 8. By arranging the devices, the reaction system can be ensured to be carried out efficiently and orderly.
The liquid storage tank 1 can be used for storing liquid wastewater to perform subsequent reaction, and liquid wastewater can be pretreated in the liquid storage tank 1. The gas-liquid mixer 3 is used to mix the pretreatment liquid with the oxidizing agent, and then the oxidation reaction is performed in the oxidation reactor 6. The oxidation reactor 6 is a tower structure which can promote the sufficient mixing of gas and liquid, and is made of a bimetal composite plate consisting of at least one of TA2, TA9, TA10, ZR702 and the like and at least one of carbon steel, 304 stainless steel or 316 stainless steel.
In the present invention, the temperature control system comprises a heating medium and/or a heat exchanger 4. The temperature control system can control the temperature of the whole reaction system, and the temperature control precision is +/-5 ℃. The heating medium may be an electric heating medium, or may be a heater 5, electric tracing, or the like. The heat exchanger 4 can be used to heat the reaction mass with the heat released from the dwell system, thereby saving energy.
The pressure maintaining system includes a pressure pump 2 and/or a pressure reducing valve 7, etc., wherein the pressure pump 2 adjusts the pressure of the reaction system to the reaction pressure. The pressure reducing valve 7 may be used to reduce the pressure of the reaction system, and the pressure reducing valve 7 is not particularly limited in the present invention as long as the valve can achieve pressure reduction, and specifically, may be a regulating valve, a back pressure valve, a ball valve, a pressure relief valve, or the like. Thereby effectively controlling the pressure of the reaction system, and the control precision of the pressure is +/-0.1 MPa.
In some specific embodiments, as shown in fig. 2, the apparatus of the present invention comprises a liquid storage tank 1, an oxidation reactor 6, and a gas-liquid separation tank 8, which are connected in series; wherein the content of the first and second substances,
the liquid storage tank 1 is used for storing liquid wastewater, the liquid wastewater is obtained by removing solid substances in the polyether polyol production wastewater, and specifically, the solid substances can be removed by using a filter; moreover, the liquid wastewater can be pretreated in the liquid storage tank 1 to obtain pretreatment liquid;
the oxidation reactor 6 is used for mixing the pretreatment liquid with an oxidant in the presence of a catalyst and carrying out an oxidation reaction to obtain a reaction product;
and a gas-liquid separation tank 8 for performing gas-liquid separation of the reaction product.
Preferably, a pressure pump 2 is also arranged between the liquid storage tank 1 and the oxidation reactor 6; a pressure reducing valve 7 is also arranged between the oxidation reactor 6 and the gas-liquid separation tank 8; wherein the content of the first and second substances,
a pressure pump 2 for adjusting the pressure of the reaction system to a reaction pressure; the pressure reducing valve 7 is used to reduce the pressure of the reaction system.
Further, between the pressure pump 2 and the oxidation reactor 6, the apparatus of the present invention further comprises a heating medium and/or a heat exchanger 4; wherein the content of the first and second substances,
the heat exchanger 4 can be used for heating the reaction materials by using the heat released by the pressure maintaining system; the heating medium is used to start the heating medium when the reaction temperature is insufficient, so that the reaction can be carried out at a suitable temperature.
Further, the apparatus of the present invention may further comprise a gas supply device 9, wherein the gas supply device 9, such as an air compressor, is mainly used for rapidly supplying oxygen when oxygen is required in the reaction system.
In addition, a gas-liquid mixer 3 is also arranged between the pressure pump 2 and the heating medium and/or the heat exchanger 4; wherein the content of the first and second substances,
the gas-liquid mixer 3 is used to mix gas and liquid when not heated and pressurized, so that danger can be avoided and the subsequent reaction can be facilitated.
In the invention, the process flow system is connected with the control cabinet, the control ranges and the upper and lower limits of temperature and pressure are set, and when the condition change exceeds the control range, linkage control is performed.
Examples
Embodiments of the present invention will be described in detail below with reference to examples, but those skilled in the art will appreciate that the following examples are only illustrative of the present invention and should not be construed as limiting the scope of the present invention. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
Example 1
Get the organic waste water of high concentration that polyether polyol device discharged out, through filtering the solid suspended solid among them of separation, the organic liquid waste water solution that obtains, through gas chromatography-mass spectrometry analyzer known the inside composition have: acrylonitrile, styrene, isopropanol and other components are analyzed by a COD rapid analyzer to obtain the liquid wastewater with the COD value of 25600mg/L and the BOD5/COD value of 0.12; the detection method of BOD5 comprises the following steps: in a microorganism laboratory, a water sample is diluted by 10 times and filled into a culture bottle, the culture bottle is sealed and is airtight, and the bottle is placed in an incubator for 5 days under the constant temperature condition of 20 ℃. The dissolved oxygen concentration is measured before and after the culture, and the oxygen consumption mass per liter of water, namely the BOD5 value can be calculated according to the difference between the dissolved oxygen concentration and the dissolved oxygen concentration.
Putting liquid wastewater into a liquid storage tank, adding a sulfuric acid solution to adjust the pH value of the liquid wastewater to 2.0 to obtain a pretreatment solution, adding copper sulfate serving as a catalyst into the pretreatment solution, wherein the concentration of the catalyst is 300ppm, fully mixing the catalyst with air containing 100% of oxygen of the COD value of the liquid wastewater, and conveying the air to an oxidation reactor for reaction, wherein the reaction conditions are as follows: reacting for 2 hours at the temperature of 220 ℃ and the pressure of 4.8Mpa, cooling the treated liquid wastewater by a condenser, introducing the cooled liquid wastewater into a gas-liquid separation tank at the temperature of 45 ℃ after passing through a pressure reducing valve and an adjusting valve, discharging gas at the upper part of the tank, and discharging liquid from the lower part of the tank to obtain a reaction product.
The liquid after gas-liquid separation analyzed by gas chromatography-mass spectrometry (GCMS) no longer contained acrylonitrile, styrene, etc., and its COD value was 3200mg/L, and the COD removal rate was 87.5%, in which the BOD5/COD value increased from 0.12 before reaction to 0.95.
Example 2
High-concentration organic wastewater discharged by a polyether polyol device is taken, solid suspended matters are centrifugally separated from the high-concentration organic wastewater, and the obtained organic liquid wastewater solution can be known to have the following components through a gas chromatography-mass spectrometer: acrylonitrile, styrene, isopropanol and other components are analyzed by a COD rapid analyzer to obtain the liquid wastewater with the COD value of 30000mg/L and the BOD5/COD value of 0.09; the detection method of BOD5 comprises the following steps: in a microorganism laboratory, a water sample is diluted by 10 times and filled into a culture bottle, the culture bottle is sealed and is airtight, and the bottle is placed in an incubator for 5 days under the constant temperature condition of 20 ℃. The dissolved oxygen concentration is measured before and after the culture, and the oxygen consumption mass per liter of water, namely the BOD5 value can be calculated according to the difference between the dissolved oxygen concentration and the dissolved oxygen concentration.
Putting liquid wastewater into a liquid storage tank, adding a certain amount of nitric acid to adjust the pH value of the liquid wastewater to 1.5 to obtain a pretreatment solution, adding copper nitrate serving as a catalyst into the pretreatment solution, wherein the concentration of the catalyst is 500ppm, fully mixing the catalyst with air with oxygen content of 150% of the COD value of the liquid wastewater, and conveying the air to an oxidation reactor for reaction, wherein the reaction conditions are as follows: reacting for 2h at 240 ℃ and 4.6Mpa, cooling the treated liquid wastewater by a condenser, introducing the cooled liquid wastewater into a gas-liquid separation tank at 45 ℃, passing through a pressure reducing valve and an adjusting valve, discharging the gas at the upper part of the tank, and discharging the liquid from the lower part of the tank to obtain a reaction product.
The liquid solution after gas-liquid separation analyzed by gas chromatography-mass spectrometry (GCMS) no longer contained acrylonitrile, styrene, etc., and its COD value was measured to be 2400mg/L, and the COD removal rate was 92%, in which the BOD5/COD value increased from 0.09 before reaction to 0.93.
Example 3
Taking out a part of mixed high-concentration wastewater discharged from a polyether polyol production device, filtering and separating to obtain a liquid wastewater solution, wherein the components comprise acrylonitrile, styrene, azobisisobutyronitrile and the like through analysis, and the COD value of the wastewater is 28000mg/L and 0.1 of BOD5/COD value through analysis of a COD rapid tester, wherein the detection method of BOD5 comprises the following steps: in a microorganism laboratory, a water sample is diluted by 10 times and filled into a culture bottle, the culture bottle is sealed and is airtight, and the bottle is placed in an incubator for 5 days under the constant temperature condition of 20 ℃. The dissolved oxygen concentration is measured before and after the culture, and the oxygen consumption mass per liter of water, namely the BOD5 value can be calculated according to the difference between the dissolved oxygen concentration and the dissolved oxygen concentration.
Putting liquid wastewater into a liquid storage tank, adding a certain amount of sulfuric acid into the solution to adjust the pH value of the liquid wastewater to 2 to obtain a pretreatment solution, adding ferrous sulfate serving as a catalyst into the pretreatment solution, wherein the concentration of the catalyst is 800ppm, fully mixing the catalyst with air containing oxygen of 150% of the COD value of the liquid wastewater, and conveying the air to an oxidation reactor for reaction, wherein the reaction conditions are as follows: reacting for 2 hours at the temperature of 250 ℃ and the pressure of 5Mpa, cooling the treated liquid wastewater by a condenser, introducing the cooled liquid wastewater into a gas-liquid separation tank at the temperature of 45 ℃ after passing through a pressure reducing valve and an adjusting valve, discharging gas at the upper part of the tank, and discharging liquid from the lower part of the tank to obtain a reaction product.
The liquid solution after gas-liquid separation is analyzed by a gas chromatography-mass spectrometer (GCMS) to contain trace amounts of refractory organic matters such as acrylonitrile, styrene and the like, the COD value is tested to be 3000mg/L, the COD removal rate is 89.3 percent, wherein the BOD5/COD value is increased to 0.9 from 0.1 before reaction.
Comparative example 1
Taking out a part of mixed high-concentration wastewater discharged from a polyether polyol production device, filtering and separating to obtain a liquid wastewater solution, wherein the components comprise acrylonitrile, styrene, azobisisobutyronitrile and the like through analysis, and the COD value of the wastewater is 30000mg/L and the BOD5/COD value is 0.12 through analysis of a COD rapid determinator. The detection method of BOD5 comprises the following steps: in a microorganism laboratory, a water sample is diluted by 10 times and filled into a culture bottle, the culture bottle is sealed and is airtight, and the bottle is placed in an incubator for 5 days under the constant temperature condition of 20 ℃. The dissolved oxygen concentration is measured before and after the culture, and the oxygen consumption mass per liter of water, namely the BOD5 value can be calculated according to the difference between the dissolved oxygen concentration and the dissolved oxygen concentration.
Fully mixing the liquid wastewater with air with oxygen content of 130% of the COD value of the liquid wastewater, and conveying the mixture into an oxidation reactor 6 for reaction, wherein the reaction conditions are as follows: reacting for 2 hours at the temperature of 250 ℃ and the pressure of 5Mpa, cooling the treated liquid wastewater by a condenser, introducing the cooled liquid wastewater into a gas-liquid separation tank at the temperature of 45 ℃ after passing through a pressure reducing valve and an adjusting valve, discharging gas at the upper part of the tank, and discharging liquid from the lower part of the tank to obtain a reaction product.
The liquid solution after gas-liquid separation analyzed by gas chromatography-mass spectrometry (GCMS) still contains a certain amount of non-degradable organic matters such as acrylonitrile, styrene and the like, the COD value is tested to be 9700mg/L, the COD removal rate is only 67.67%, wherein the BOD5/COD value is only increased to 0.5 from 0.12 before reaction.
It should be noted that, although the technical solutions of the present invention are described by specific examples, those skilled in the art can understand that the present invention should not be limited thereto.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen in order to best explain the principles of the embodiments, the practical application, or improvements made to the technology in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Claims (10)
1. A treatment method of polyether polyol production wastewater is characterized by comprising the following steps:
removing solid matters in the polyether polyol production wastewater to obtain liquid wastewater;
pretreating the liquid wastewater to obtain a pretreatment solution;
mixing the pretreatment solution with an oxidant in the presence of a catalyst and carrying out an oxidation reaction to obtain a reaction product;
cooling and depressurizing the reaction product, and then carrying out gas-liquid separation.
2. The processing method according to claim 1, characterized in that said pre-processing comprises: and adjusting the pH value of the liquid wastewater to 0.1-5 by using acid.
3. The treatment method according to claim 1 or 2, wherein the catalyst comprises a metal salt catalyst, wherein a concentration of the metal salt catalyst in the pretreatment liquid is 5ppm to 8000 ppm; and/or
The metal salt comprises one or the combination of more than two of copper salt, iron salt, manganese salt, lead salt, zinc salt and nickel salt.
4. The treatment according to any one of claims 1 to 3, wherein the oxidizing agent comprises oxygen, and wherein the oxygen content in the oxidizing agent is 50% to 300% of the COD of the wastewater from the production of polyether polyol.
5. The process according to any one of claims 1 to 4, wherein the oxidation reaction is carried out at a reaction temperature of 150 ℃ to 300 ℃, a reaction pressure of 0.5MPa to 8MPa, and a reaction time of 0.2 hours to 10 hours.
6. The process according to any one of claims 1 to 5, wherein the temperature of the reaction product after cooling is 60 ℃ or lower, and the pressure after depressurization is 0.1MPa to 6.1 MPa.
7. An apparatus for carrying out the method for treating polyether polyol production wastewater according to any one of claims 1 to 6, comprising a reaction system, a temperature control system and a pressure maintaining system which are connected.
8. The apparatus of claim 7, wherein the reaction system comprises one or a combination of two or more of a liquid storage tank, a gas supply device, a gas-liquid mixer, an oxidation reactor, and a gas-liquid separation tank.
9. The apparatus according to claim 7 or 8, wherein the temperature control system comprises an electrical heating medium and/or a heat exchanger.
10. An apparatus according to any one of claims 7 to 9, wherein the pressure holding system comprises a pressure pump and/or a pressure relief valve.
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| CN113860587A (en) * | 2021-10-09 | 2021-12-31 | 南京大学 | Styrene-containing wastewater pretreatment method |
| CN113860640A (en) * | 2021-10-09 | 2021-12-31 | 南京大学 | Method for treating high-concentration organic wastewater in polymer polyol production process |
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| CN112010494A (en) * | 2019-10-29 | 2020-12-01 | 沈阳化工研究院设计工程有限公司 | Method for treating wastewater generated by synthesizing para-ester by mercaptoethanol method |
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| CN112010494A (en) * | 2019-10-29 | 2020-12-01 | 沈阳化工研究院设计工程有限公司 | Method for treating wastewater generated by synthesizing para-ester by mercaptoethanol method |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113860587A (en) * | 2021-10-09 | 2021-12-31 | 南京大学 | Styrene-containing wastewater pretreatment method |
| CN113860640A (en) * | 2021-10-09 | 2021-12-31 | 南京大学 | Method for treating high-concentration organic wastewater in polymer polyol production process |
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