CN102826701B - Method for deep purification of leachate by using single factor separation - Google Patents

Abstract

Leachate single-factor separation deep purification method: gas-liquid separation of water vapor containing gaseous pollutants and concentrated leachate containing high-boiling point pollutants; water vapor is converted into superheated steam and then extracted with low-boiling point pollutants The extraction agent solution is used for gas-liquid contact, so that the low-boiling point pollutant extractant solution absorbs and neutralizes the gaseous pollutants in the superheated steam, and converts them into high-boiling point neutralized products that are separated from the superheated steam, containing gaseous pollutants After the superheated water vapor of the substance is absorbed by the low-boiling point pollutant extractant solution, the gaseous pollutants are condensed, and the condensed water is discharged for recycling. The method of the present invention only utilizes the single factor of different boiling points of water in the leachate and various pollutants to carry out deep purification, and has the advantages of simple process, low equipment cost and treatment cost, and can realize high-efficiency and advanced treatment of the leachate .

Description

Leachate Single Factor Separation Advanced Purification Method

technical field

The invention belongs to the technical field of sewage treatment, and in particular relates to a treatment method for leachate of garbage.

Background technique

For landfill leachate with high concentration of pollutants, complex components, high toxicity or poor biodegradability, the concentration of pollutants in it is more than 100 times that of ordinary sewage, which is extremely difficult to treat, and a large amount of sludge and concentrated liquid will be produced after treatment. , has become a long-term industrial problem that is not easy to solve.

The problems existing in the existing leachate treatment methods mainly include:

Biological method: the equipment is large in size, and carbon sources need to be added, the removal is not complete, and a large amount of sludge is generated;

Blow-off method: high energy consumption, high drug consumption, incomplete removal, easily affected by environmental conditions;

Adsorption method: high equipment cost, high drug consumption, frequent regeneration, and secondary treatment of flushing water;

Oxidation method: high equipment cost, high drug consumption/energy consumption;

Nanofiltration method: Because the leachate is a high-concentration pollutant, the membrane is seriously polluted; because the small molecular pollutants are similar in size to water molecules, the removal rate is low and it is difficult to meet the standard; a large amount of concentrated liquid is produced, which is difficult to dispose of.

Reverse osmosis method: high energy consumption; because the leachate is a high-concentration pollutant, the membrane is seriously polluted; because the small molecular pollutants are similar in size to water molecules, the removal is not thorough and difficult to meet the standard; a large amount of concentrated liquid is produced, which is difficult to dispose of .

None of the above treatment methods can meet the emission standards. The treatment methods commonly used in engineering now are coagulation, sedimentation, biological anaerobic digestion, biological aerobic treatment, biological nitrification and denitrification treatment, membrane biochemical reactor, various The repeated combination and superposition of a variety of oxidants with various catalysts, catalysts, ultraviolet light, ultrasonic treatment, nanofiltration membrane/reverse osmosis membrane treatment, etc., involves a variety of physical factors, chemical factors and biological oxidation factors. However, all these multi-factor combined treatment methods generally have a large number of equipment, large volume, and are easily affected by water quality and environmental conditions. Multiple treatment factors affect and interfere with each other, and the system has high energy consumption, high chemical consumption, and high operating costs. The management is difficult, it cannot adapt to leachate in different periods, the removal is not thorough, it is difficult to meet the discharge standard, and a large amount of concentrated liquid and sludge that are more difficult to handle are produced during the treatment process.

The above-mentioned multi-factor combination treatment method (also known as multi-factor method) will produce a large amount of sludge and concentrate that is difficult to dispose of (accounting for more than 30% to 40% of the total leachate), and for a long time most of these sludge The result is that the concentration of pollutants in the leachate in the landfill will continue to increase, and it will gradually approach the upper limit of the concentration that can be treated within 3-4 years, so that the treatment efficiency will be reduced. Until it fails, and the typical design life of the landfill is more than ten years, thus leaving major troubles.

Contents of the invention

The technical problem to be solved by the present invention is to provide a leachate single-factor separation advanced purification method with simple process, low equipment cost and treatment cost, high efficiency and three-phase separation advanced treatment of landfill leachate.

The technical solution for solving the above problems is: the inventive method comprises the following content:

A. Heating the leachate to generate water vapor, the low-boiling point pollutants in the leachate are vaporized into gaseous pollutants and enter the water vapor, and the water vapor containing gaseous pollutants and the concentrated leachate containing high-boiling point pollutants are vaporized liquid separation;

B. Pass the separated water vapor containing gaseous pollutants through the superheated generator to make it into superheated steam, and make gas-liquid contact between the superheated steam and the low-boiling point pollutant extractant solution to extract low-boiling point pollutants The agent solution absorbs and neutralizes the gaseous pollutants in the superheated steam, converts them into high-boiling point neutralization products and separates them from the superheated steam;

C. When the superheated steam is in gas-liquid contact with the low boiling point pollutant extractant solution, the superheated degree of superheated steam is controlled to prevent the condensation of the superheated steam to the low boiling point pollutant extractant solution, so that the low boiling point The pollutant extractant solution is not diluted; at the same time, the water in the low boiling point pollutant extractant solution is partially vaporized by using the superheat value of the superheated steam to increase the concentration of the neutralized product in the low boiling point pollutant extractant solution;

D. After the superheated steam containing gaseous pollutants is absorbed by the low boiling point pollutant extractant solution, the gaseous pollutants are condensed, and the condensed water is discharged for recycling.

Further, the degree of superheat of the superheated steam is controlled to be 3°C to 40°C higher than the temperature of the saturated water vapor, and the degree of superheat is at least 1°C higher than the boiling point temperature of the low boiling point pollutant extractant solution;

The method of the present invention uses only the difference of the boiling point (vaporization or condensation temperature) between water and various pollutants to completely separate the pollutants, so it is called a single factor separation method;

described in the method of the present invention

High boiling point pollutants: refers to various pollutants in the leachate whose boiling point is higher than that of water;

Low boiling point pollutants: refers to various pollutants in leachate whose boiling point is close to or lower than that of water;

Low-boiling point pollutant extractant solution: refers to the acidic or alkaline aqueous solution that can neutralize the low-boiling point gaseous pollutants in superheated steam to form non-volatile soluble salts, or contain such acidic or alkaline High-boiling organic solvents for aqueous solutions.

After the superheated steam containing gaseous pollutants is in gas-liquid contact with the low boiling point pollutant extractant, a process of mass transfer to the liquid surface of the low boiling point pollutant extractant will occur, and then be neutralized in the liquid and converted into high Soluble salts at the boiling point can no longer enter the water vapor, so that the purpose of separation from the superheated steam can be achieved through mass transfer separation.

Most of the pollutants in the leachate, including the most difficult to handle, the most toxic, and the most diverse pollutants, are all high-boiling point pollutants. After the method of the present invention heats the landfill leachate to generate water vapor, the leachate The low-boiling point pollutants in the liquid become gaseous and enter the water vapor, while the high-boiling point pollutants are retained in the concentrated leachate, and the easily volatile low-boiling point pollutants in the leachate are converted into gaseous pollutants through gas-liquid separation The pollutants and water vapor are extracted together, so that the leachate becomes a concentrated solution with a greatly reduced volume. The pollutants contained in the concentrated solution are mainly high-boiling point pollutants, and the volatile substances contained in the leachate cause secondary pollution. The harmful substances with low boiling point are separated out. Since the volume of this concentrated leachate is greatly reduced, it is easy to recycle; and because it does not contain volatile pollutants, it will not cause secondary pollution during recycling.

For the separated water vapor containing low-boiling gaseous pollutants, the method of the present invention makes it into superheated steam and then carries out sufficient gas-liquid contact with the low-boiling point pollutants extractant solution, and the gaseous pollution in the superheated vapor The gas-liquid mass transfer process occurs between the substance and the low-boiling point pollutant extractant solution. After the gaseous pollutant enters the liquid, it undergoes a neutralization reaction with the low-boiling point pollutant extractant and transforms into a high-boiling point compound, which can be obtained through gas-liquid contact. The balance is continuously shifted to the liquid state to achieve the purpose of separating low-boiling gaseous pollutants from superheated steam.

During the gas-liquid contact, through the mass transfer process, the low boiling point pollutant extractant solution will gradually contain a higher concentration of soluble substances, such as acid and neutralization product salt, or alkali and neutralization product salt, resulting in the solution The raising of boiling point, when the boiling point of low-boiling point pollutant extracting agent solution rises beyond water vapor condensation temperature, can cause the condensation of water vapor on the surface of low boiling point pollutant extracting agent solution and make solution be diluted, so the present invention will Before the water vapor containing gaseous pollutants undergoes mass transfer separation, it is first turned into superheated steam, and then the superheated steam is contacted with the low boiling point pollutant extractant solution in gas-liquid contact, so that the superheated steam can be used The degree of superheat prevents the condensation of water vapor to the low-boiling point pollutant extractant solution, avoiding the dilution of the low-boiling point pollutant extractant solution by condensed water; The superheated sensible heat value of the high value can partially vaporize the moisture in the low boiling point pollutant extractant solution, increase the concentration of neutralization products in the low boiling point pollutant extractant solution, achieve the purpose of energy saving, and provide further Create conditions for efficient separation.

During the gas-liquid contact process, the low-boiling point pollutant extractant solution can also cool the superheated steam, reduce its superheat value, and improve the subsequent heat exchange and condensation efficiency; thus, it can replace the superheated steam In the process of spraying cooling water to reduce its superheat value, the positive effect of saving energy and equipment is achieved.

By adopting the method of the invention, the leachate can be deeply separated into products that are easy to recover and will not cause secondary pollution in the recovery process.

The method of the present invention only uses the single factor (single factor) of different boiling points of water in the leachate and various pollutants for deep purification, but the effect is better than that of using multiple physical factors, multiple chemical factors and multiple biological oxidation factors ( Multi-factor) combined purification method; and has the advantages of simple process, low equipment cost and treatment cost, and can achieve high-efficiency and advanced treatment of leachate.

Description of drawings

Fig. 1, schematic flow chart of the method of the present invention

Fig. 2, process flow chart of the present invention's method embodiment 1

Fig. 3, implement the equipment structure diagram used for the method of embodiment 1 of the present invention

Fig. 4, implement the equipment structure diagram used for the method of embodiment 2 of the present invention

Detailed ways

Example 1

Fig. 2 is the process flow diagram of this embodiment, and Fig. 3 is a schematic diagram of the device structure used in implementing this embodiment.

In this example, the sensible heat exchange device 4 is used to preheat the leachate, and then the latent heat exchange device 3 is used to heat the leachate to generate steam. The process is as follows:

The leachate pumped by the leachate supply device 8 is heated by the heating side of the sensible heat exchange device 4 and the evaporation side of the latent heat exchange device 3, and then enters the gas-liquid separation device 5 through the throttle valve 7;

The water vapor containing low-boiling gaseous pollutants separated in the gas-liquid separation device 5 is output from the water vapor outlet 51 of the gas-liquid separation device 5, and generates superheated steam through the heat generating device. The superheat generating device of this example is a gas compressor 1. By mechanically boosting water vapor containing gaseous pollutants to turn it into superheated steam, in this example, the pressure of water vapor is increased from 1 atm to 1.2 atm, so that the condensation temperature of water vapor is increased. Due to the input of compression energy, The temperature of water vapor is increased more to become superheated vapor;

Then, the superheated steam formed by the superheat generator is input into the gas-liquid contact device 2, and the gas-liquid contact is carried out with the low boiling point pollutant extractant solution at the boiling point in the device. The gas-liquid contact device 2 of this example adopts The tray type gas-liquid contact device may also use a spray device and/or a gas-liquid differential contact device.

If the superheated steam contains gaseous alkaline pollutants, the low-boiling point pollutant extractant solution uses an acidic aqueous solution that can neutralize it (for example, an acidic aqueous solution such as hydrochloric acid, sulfuric acid, or nitric acid can be used). With sufficient gas-liquid contact, the gaseous basic pollutants in the water vapor are adsorbed into the low-boiling point pollutant extractant solution and neutralized with the acidic aqueous solution to form high-boiling point non-volatile soluble salts.

If the water vapor contains gaseous acidic pollutants (such as H2S, acidic substances of organic acids), the low-boiling point pollutant extractant solution uses an alkaline aqueous solution that can neutralize it (for example, sodium hydroxide, Alkaline aqueous solution such as sodium carbonate), after sufficient gas-liquid contact, the gaseous acidic pollutants in the water vapor are adsorbed into the low-boiling point pollutant extractant solution and neutralized with the alkaline aqueous solution to form high-boiling point Volatile soluble salts.

The gas-liquid contact device 2 of this example is provided with a circulating spray device 23, which is used to continuously circulate the low-boiling point pollutant extractant solution at the bottom of the gas-liquid contact device 2 to the upper part of the device for spraying, and fully complete the process with the input superheated steam. gas-liquid contact. In this way, the pollutant extractant solution can be continuously cyclically evaporated and concentrated, and the gaseous pollutants in the superheated steam can be repeatedly absorbed, so that the concentration of pollutants absorbed in the pollutant extractant solution can reach a higher level. Then the neutralization product in the low boiling point pollutant extractant solution that has reached a certain concentration is separated for recycling;

In this example, the degree of superheat of the superheated steam is 11°C higher than the temperature of saturated water vapor, and the degree of superheat is 7°C higher than the boiling temperature of the low-boiling point pollutant extractant solution;

Usually, the present invention controls the degree of superheat of water vapor so that the degree of superheat is 3°C to 40°C higher than the temperature of saturated water vapor, and the degree of superheat is at least 1°C higher than the boiling point temperature of the low boiling point pollutant extractant solution;

This is because the aqueous solution of the low-boiling point pollutant extractant contains a certain concentration of the low-boiling point pollutant extractant and the dissolved matter of the neutralized product (such as the dissolved matter of hydrochloric acid and ammonium chloride, or the dissolved matter of sodium hydroxide and sodium acetate). substances, etc.), when the mass transfer process increases the concentration of dissolved substances in the low-boiling point pollutant extractant solution, it will cause the boiling point of the solution to rise, causing superheated steam to condense on the surface of the low-boiling point pollutant extractant solution. Its dilution; for example, the dissolved matter in the low-boiling point pollutant extractant solution can only reach a very low concentration when it is in contact with saturated water vapor. In this example, by making the superheat value of the water vapor higher than the boiling point rise value, it is possible to avoid the dilution of the low boiling point pollutant extractant solution by condensed water, thereby realizing the continuous circulation and absorption of the low boiling point pollutant extractant solution to dissolve the contained When the superheated degree of superheated steam is 3°C higher than the saturated water vapor temperature, the concentration of dissolved substances in the low boiling point pollutant extractant solution can reach at least 10%.

The continuous use of the low-boiling point pollutant extractant solution for absorption and neutralization will increase the concentration of total dissolved substances. When the concentration of total dissolved substances reaches about 10%, the superheated degree of superheated steam must be higher than that of saturated water vapor. The temperature is at least 3°C; the maximum increase in the boiling point of the low-boiling point pollutant extractant solution can reach about 8°C. In this case, the superheated degree of superheated steam must be higher than the temperature of saturated water vapor by at least 9°C;

However, if the degree of superheat exceeds 40°C, the efficiency of the superheat generator will drop too much and the overall efficiency will decrease. Therefore, the preferred control range of the degree of superheat of the water vapor in the present invention is 3°C to 40°C higher than the temperature of saturated water vapor;

The superheated calorific value of the superheated part of the superheated steam that is higher than the rising value of the boiling point of the low-boiling point pollutant extractant solution can make the low-boiling point pollutant extractant solution evaporate and concentrate, thereby avoiding only low-concentration absorption and The disadvantages of neutralizing the product and then consuming a large amount of heat energy to evaporate and concentrate the low boiling point pollutant extractant solution.

The superheated steam will be cooled when in contact with the low-boiling point pollutant extractant solution, and the superheat value will be reduced. If it drops below the boiling point of the low-boiling point pollutant extractant by 1°C, which is closer to the temperature of saturated water vapor, there will be overheating Water vapor reduces the efficiency of the subsequent heat exchange device and increases energy consumption.

Therefore, the present invention selects the superheat of water vapor to be at least 1°C higher than the boiling temperature of the low boiling point pollutant extractant solution;

In this example, the gas-liquid contact device 2 is provided with a low-boiling point pollutant extractant solution inlet 24, which is used to fill the gas-liquid contact device with a low-boiling point pollutant extractant solution, and the lower part is provided with a low-boiling point pollutant extractant solution outlet 21; Pollutant extraction agent outlet 21 is connected with crystallization and solid-liquid separation device 9 .

The process of separating the neutralized product in the low boiling point pollutant extractant solution that reaches a certain concentration for recycling is:

In the gas-liquid contact device 2, control the low-boiling point pollutant extractant solution to absorb the concentration of the neutralization product generated by pollutants to rise to the degree that crystallized solids can be precipitated after cooling, and then part of the pollutant extractant solution flows into the crystallization and solid After cooling in the liquid separation device 9, the crystalline solid deposits are separated out, and after solid-liquid separation, the crystalline solid deposits are discharged from the crystallization deposit outlet 91 to prepare usable chemical raw materials. The liquid is discharged from the outlet 92 and returned to the gas-liquid contact device 2 after readjusting the pH value, and repeats the process of absorbing, evaporating and concentrating.

In this example, the superheated steam after the gaseous pollutants are absorbed by the low-boiling point pollutant extractant solution is used to heat the input leachate, specifically:

The water vapor after the gaseous pollutants are absorbed by the low-boiling point pollutant extractant solution first transfers heat to the leachate through the latent heat exchange device 3, and then transfers the heat to the latent heat exchange device 4 through the sensible heat exchange device to be input into the latent heat exchange. The leachate on the evaporation side of the device and the heated leachate on the evaporation side of the latent heat exchange device 3 are input into the gas-liquid separation device 5 for gas-liquid separation; the upper part of the gas-liquid separation device 5 is provided with a steam outlet 51 for Output the separated water vapor, the lower part is provided with a concentrated liquid outlet 52, which is used to output the concentrated leachate reaching a certain concentration, the lower part of the gas-liquid separation device 5 is connected to the evaporation side of the latent heat heat exchange device through the circulation device 6, and is used to make the leachate Drainage is heated and separated by circulation.

specifically is:

The above-mentioned purified water vapor from which low-boiling point pollutants have been removed is transported to the condensation side of the latent heat exchange device 3. Since it has been increased in pressure and the condensation temperature of the water vapor is increased, it can be condensed at a higher temperature and release gas. The latent heat is transferred to the leachate on the evaporation side through the latent heat exchange device to heat it to the boiling point, and the leachate on the evaporation side of the latent heat exchange device is input into the gas-liquid separation device 5 for gas-liquid separation;

In this example, a throttling valve 7 is provided on the output channel of the latent heat exchange device 3 on the evaporation side of the gas-liquid separation device, so that the leachate is in a pressurized state when passing through the latent heat exchange device, and passes through the evaporation side of the latent heat exchange device. The leachate output from the throttle valve 7 reaches the gas-liquid separation device 5 and is decompressed, where gasification and evaporation occur in the gas-liquid separation device 5 .

When the leachate passes through the latent heat exchange device, it is in a pressurized state, so that the leachate does not vaporize or reduces the occurrence of gasification in the latent heat exchange device, so as to prevent it from vaporizing on the surface of the evaporation side of the heat exchange device Local concentration is caused, thereby avoiding the fouling tendency of the heat exchange surface of the latent heat exchange device, so as to improve the heat exchange efficiency.

After the leachate is gasified and evaporated in the gas-liquid separation device 5, the separated water vapor containing gaseous low-boiling point pollutants flows out from the water vapor outlet 51, and is input to the aforementioned gas compressor 1 through the mechanical power booster device. Gas-liquid contact device 2;

The concentrated leachate separated in the gas-liquid separation device 5 passes through the circulation pump 6 and returns to the latent heat exchange device 3 to be heated again. After the liquid is concentrated to a certain extent, it is discharged from the concentrated liquid outlet 52.

The condensed water at a higher temperature obtained after the purified water vapor from which low-boiling-point pollutants have been condensed on the condensation side of the latent heat exchange device 3 is input to the heat release side of the sensible heat exchange device 4, and the sensible heat On the heating side of the exchange device, the leachate prepared to be input to the latent heat heat exchange device 3 is preheated, and the water vapor from which pollutants have been removed undergoes such sufficient heat exchange in the latent heat and sensible heat heat exchange device to generate condensed water, It is discharged from the condensed water outlet 41 and becomes discharge water meeting national standards.

If the COD and BOD in the condensed water after the above treatment still exceed the standard, a biological treatment device can be added to post-treat the condensed water; a preferred solution is to use a membrane bioreactor (MBR).

At the beginning of the cycle of the system, the external heating source can be used to heat the leachate on the heat-absorbing side of the heat exchange device. The leachate in the device is heated, that is to say, after the circulation is normal, there is basically no need for external heating energy.

As mentioned above, the leachate is continuously vaporized and transformed into water vapor, and the low-boiling point pollutants also volatilize into gaseous pollutants and enter the water vapor. After gas-liquid separation of the water vapor containing gaseous pollutants and non-evaporated leachate, it is sent to a gas compressor to convert it into superheated steam, and then enters a gas-liquid contact device for extraction with a low boiling point pollutant extractant solution. The gas-liquid contact makes the gaseous pollutants absorbed by the low-boiling point pollutant extractant solution, and after the superheated steam removes the low-boiling point gaseous pollutants, it enters the heat release side of the heat exchange device to exchange heat with the leachate, and this cycle makes the whole The system runs continuously.

The low boiling point pollutant extractant solution in the gas-liquid contact device is selected for the main components of the gaseous pollutants in the superheated steam. In this example, the acidic aqueous solution is selected for the gaseous basic pollutants in the superheated steam; The gaseous pollutants in the hot water vapor are mainly non-polar organic pollutants, including alcohols such as methanol and ethanol, etc., and the low-boiling pollutant extractant containing high-boiling-point organic solvents (boiling point is higher than water) can be used to extract non-polar pollutants at the same time. Adsorb polar organic substances to achieve the purpose of separation and removal. This kind of high boiling point organic solvent can be organic hydrocarbons from C8 to C10;

If the gaseous pollutants in the superheated steam are mainly acidic substances, such as organic acids, H2S, etc., an alkaline aqueous solution can be selected as the low-boiling point pollutant extraction agent, so that the acidic pollutants can be adsorbed and converted into high-boiling point soluble salts similar substances to achieve the purpose of separating and removing them;

In this example, low-boiling gaseous pollutants in superheated steam are mainly gaseous alkaline pollutants; acidic aqueous solutions such as hydrochloric acid, sulfuric acid, and nitric acid, which have a pH value of less than 3, are used to absorb and neutralize the gaseous pollutants in the steam. gaseous alkaline pollutants (when the pH is greater than 3, the effect of removing gaseous alkaline pollutants begins to decrease significantly).

If the low-boiling gaseous pollutants in the superheated steam are mainly acidic pollutants such as hydrogen sulfide and/or organic acids, acidic aqueous solutions such as sodium hydroxide and sodium carbonate with a pH value greater than 11 can be used to remove Absorb and neutralize hydrogen sulfide and/or organic acids in water vapor (when the pH is less than 11, the effect of removing gaseous acid pollutants begins to decrease significantly).

In short, the selected low boiling point pollutant extractant solution should be able to neutralize the gaseous pollutants in the superheated steam to generate high boiling point non-volatile soluble salts.

Example 2

When the gaseous pollutants in the superheated steam contain both acidic substances and alkaline substances, a two-stage or more gas-liquid contact process can be set up so that the superheated steam passes through two or more stages of gas-liquid contact process in series. The liquid contact process, and the gas-liquid contact with the low-boiling point pollutant extractant solutions with different acidity and alkalinity, respectively, to remove the gaseous basic pollutants and gaseous acidic pollutants contained therein.

In this example, a two-stage gas-liquid contact process is set up (see Figure 4).

In the first-stage gas-liquid contact process, the low-boiling-point pollutant extractant solution containing acidic substances is used to make sufficient gas-liquid contact with the gaseous pollutants in the superheated steam to absorb the alkaline substances;

In the second-stage gas contact process, the low-boiling-point pollutant extractant solution containing alkaline substances is used for sufficient gas-liquid contact with the gaseous pollutants in the superheated steam to absorb the acidic substances;

The two-stage gas-liquid contact process is realized by the gas-liquid differential contact device gas 2 and the second gas-liquid differential contact device 10 respectively. The gas-liquid differential contact device 2 uses an aqueous solution of low-boiling pollutant extractant containing acidic substances, and the second gas-liquid differential contact device 10 uses an aqueous solution of low-boiling pollutant extractant containing alkaline substances.

If the gaseous pollutants contain more acidic substances than alkaline substances, the first-stage gas-liquid contact process uses an alkaline low-boiling point pollutant extractant solution, and the second stage uses an acidic low-boiling point pollutant extractant solution.

Example 3

Negative pressure operation, low boiling point pollutant extractant is sodium hydroxide aqueous solution, PH=12, total dissolved matter concentration 20%, relevant data and purification effect are as follows:

The purification effect meets the national standard GB1689-2008 special discharge limit and industrial reuse water standard.

Example 4

Normal pressure operation, low boiling point pollutant extractant is nitric acid aqueous solution, PH=0.2, total dissolved matter concentration 51%, relevant data and purification effect are as follows:

The purification effect meets the national standard GB1689-2008 special emission limit and agricultural recycling standard.

Example 5

Normal pressure operation, low boiling point pollutant extractant is a high boiling point organic solvent containing nitric acid aqueous solution, PH=0.3, total dissolved matter concentration 52%, relevant data and purification effect are as follows:

The purification effect meets the national standard GB1689-2008 special discharge limit and industrial reuse water standard.

The "total dissolved matter" described in the above-mentioned embodiments 3-5 refers to all dissolved matter in the solution, including low-boiling point pollutant extractant and non-volatile soluble salt substances generated by absorbing gaseous pollutants in superheated steam .

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in any form. Any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention are still within the scope of this invention. The protection scope of the technical solution of the invention.

Claims (7)

1. The leachate single-factor separation deep purification method is characterized in that it includes the following content: A. Heating the leachate to generate water vapor, the low-boiling point pollutants in the leachate are vaporized into gaseous pollutants and enter the water vapor, and the water vapor containing gaseous pollutants and the concentrated leachate containing high-boiling point pollutants are vaporized liquid separation; B. Pass the separated water vapor containing gaseous pollutants through the gas compressor to make it into superheated steam, and make gas-liquid contact between the superheated steam and the low-boiling point pollutant extractant solution to extract low-boiling point pollutants The agent solution absorbs and neutralizes the gaseous pollutants in the superheated steam, converts them into high-boiling point neutralization products and separates them from the superheated steam; C. When the superheated steam is in gas-liquid contact with the low boiling point pollutant extractant solution, the superheated degree of the superheated steam is controlled to be 3°C to 40°C higher than the saturated water vapor temperature, and the superheated degree is higher than that of the low boiling point pollutants The boiling point temperature of the extractant solution is at least 1°C to prevent the condensation of superheated steam to the low-boiling point pollutant extractant solution, so that the low-boiling point pollutant extractant solution is not diluted; Moisture in the low boiling point pollutant extractant solution is partially vaporized to increase the concentration of neutralized products in the low boiling point pollutant extractant solution; D. After the superheated steam containing gaseous pollutants is absorbed by the low boiling point pollutant extractant solution, the gaseous pollutants are condensed, and the condensed water is discharged for recycling. 2. The deep purification method of single-factor separation of leachate according to claim 1, characterized in that, the superheated steam formed by the gas compressor is input into the gas-liquid contact device (2), and the The low-boiling point pollutant extractant solution is subjected to gas-liquid contact, and the gas-liquid contact device (2) is a tray-type gas-liquid contact device, or a spray device and/or a gas-liquid differential contact device. 3. The leachate single-factor separation advanced purification method according to claim 1, characterized in that the water vapor after the gaseous pollutants are absorbed by the low-boiling point pollutant extractant solution first passes through the latent heat heat exchange device (3) to The heat is transferred to the leachate, and then through the sensible heat exchange device (4), the heat is transferred to the leachate to be input to the evaporation side of the latent heat exchange device, and the leachate heated on the evaporation side of the latent heat exchange device (3) The liquid is input into the gas-liquid separation device (5) for gas-liquid separation; the upper part of the gas-liquid separation device (5) is provided with a water vapor outlet (51) for outputting the separated water vapor, and the lower part is provided with a concentrated liquid outlet (52 ), used to output concentrated leachate reaching a certain concentration; the lower part of the gas-liquid separation device (5) is connected to the evaporation side of the latent heat exchange device through the circulation device (6), and is used to circulate the leachate for heating and separation. 4. The deep purification method of single-factor separation of leachate according to claim 3, characterized in that a throttling valve (7) is provided on the output channel of the latent heat heat exchange device (3) evaporation side gas-liquid separation device so that the leachate is in a pressurized state when it passes through the latent heat exchange device, and the leachate output from the evaporation side of the latent heat exchange device through the throttle valve (7) reaches the gas-liquid separation device (5) and is decompressed , vaporization occurs in the gas-liquid separation device (5). 5. The leachate single-factor separation advanced purification method according to claim 1, characterized in that the obtained condensed water is subjected to biological purification treatment using a bioreactor. 6. The leachate single-factor separation deep purification method according to claim 1 is characterized in that, the low-boiling pollutant extractant solution with a pH value of less than 3 is used to absorb and neutralize the gaseous alkalinity in the superheated steam Pollutants; or use a low-boiling pollutant extractant solution with a pH value greater than 11 to absorb and neutralize gaseous acidic pollutants in superheated steam. 7. The leachate single-factor separation deep purification method according to claim 1, characterized in that two or more gas-liquid contact processes are set, so that superheated steam passes through two or more stages in series In the gas-liquid contact process, the gas-liquid contact is carried out with the low-boiling point pollutant extractant solutions with different acidity and alkalinity, and the gaseous basic pollutants and gaseous acidic pollutants contained in them are removed.

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