Feed water pretreatment process by coupling activated carbon adsorption with catalytic ozonation

Abstract

The invention discloses an activated carbon adsorption coupled ozone catalytic oxidation feed water pretreatment process, belongs to the field of feed water pretreatment, and relates to technical treatment of drinking water source micro-pollution purification. The method comprises the following steps: firstly, introducing raw water of a reservoir into the catalytic ozonation tank, and carrying out primary reaction through catalytic ozonation to realize breakage and degradation of macromolecular organic matters; secondly, entering an activated carbon adsorption tank, carrying out hydraulic retention reaction for a period of time, and adsorbing and removing organic matters which are not thoroughly degraded in the previous step; then, effluent obtained after the reaction in the activated carbon adsorption tank enters a filter to remove activated carbon particles in the water, and secondary treatment is conducted on activated carbon through a high-temperature regeneration method; and finally, backwashing water is introduced to clean dirt generated in the reaction process, so that the service life of the reaction device is prolonged, and meanwhile, the effluent quality is ensured. The advantages of catalytic ozonation and activated carbon adsorption processes are fully utilized, the catalytic ozonation and the activated carbon adsorption processes compensate each other, the operation cost is reduced, and meanwhile, the effluent quality is improved.

Description

Technical Field

[0001] The present invention belongs to the field of water pretreatment, relates to technical treatment of micro-pollution purification of drinking water sources, and specifically relates to an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process. Background Art

[0002] With the rapid development of urbanization, people's living standards have been greatly improved. Along with the acceleration of industrialization, a series of environmental pollution problems have been brought about. Among them, water pollution and water shortage are the focus of people's attention, and the public's requirements for water quality and quantity are getting higher and higher. Therefore, how to ensure the safety of drinking water is the focus of current research.

[0003] Feed water pretreatment is an important process unit in water treatment. It is a preliminary pretreatment of pollutants in water through physical, chemical and biological methods to reduce the burden of subsequent processes, better play the role of water purification and improve the quality of effluent water. At present, the widely used means of feed water pretreatment are mainly adsorption pretreatment, chemical oxidation pretreatment and biological pretreatment. Adsorption pretreatment is a specific combination of processes such as coagulation, filtration, flocculation and sedimentation of adsorbents. While reducing the turbidity of water, it can also remove some organic matter and microorganisms in water and improve the quality of effluent water. However, when the turbidity of water is high and the water quality is poor, the treatment effect of such processes is not good and it is difficult to achieve the ideal effect. Chemical oxidation pretreatment relies on the oxidation ability of ultraviolet light, hydrogen peroxide and ozone to decompose and destroy pollutants to achieve the purpose of transforming and decomposing pollutants. This method can effectively remove the number of organic pollutants in water and improve the biodegradability of organic matter, but at the same time, some organic by-products will be produced, which are difficult to remove through subsequent processes, and new pollutants will be introduced. Biological pretreatment technology has disadvantages such as poor biological stability and small scale of use, making it difficult to ensure effluent quality and actual large-scale use.

[0004] Therefore, it is urgent to develop an efficient, environmentally friendly and stable water pretreatment process to improve water treatment efficiency while ensuring that the effluent quality meets the standards and meets people's needs for safe and healthy drinking water. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a water pretreatment process by coupling activated carbon adsorption with ozone catalytic oxidation.

[0006] An activated carbon adsorption coupled ozone catalytic oxidation feed water pretreatment process is specifically completed in the following steps:

[0007] 1. Introduce the reservoir raw water into the ozone catalytic oxidation tank, add the catalyst to the reservoir raw water, generate ozone through the ozone generator, control the ozone aeration device to continuously aerate the ozone catalytic oxidation tank, and carry out catalytic reaction under the action of the catalyst for a period of time to obtain the effluent after ozone catalytic oxidation;

[0008] Second, the effluent after ozone catalytic oxidation is introduced into the activated carbon adsorption tank, the activated carbon dosage is controlled by the activated carbon metering feeder, and the hydraulic retention reaction is carried out for a period of time to achieve the removal of macromolecular organic matter in the raw water, and the effluent after the reaction in the activated carbon adsorption tank is obtained;

[0009] 3. The effluent after the reaction in the activated carbon adsorption tank enters the filter to remove the activated carbon particles in the water. The filtered effluent is collected for subsequent deep treatment. The discarded activated carbon needs to be treated twice before discharge to avoid secondary pollution caused by direct discharge.

[0010] 4. Backwash water is introduced into the ozone catalytic oxidation tank and the activated carbon adsorption tank to use the shear force of the water flow and the collision friction of the particles to clean the dirt generated during the reaction process, thereby extending the service life of the reaction device while ensuring the water quality of the effluent, and collecting the backwash water for secondary reuse.

[0011] Advantages of the present invention:

[0012] 1. The present invention discloses an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process; in the ozone catalytic oxidation process, since ozone has a high redox potential (2.08V), it can oxidize most of the organic matter in the water, and the secondary pollution generated is small. In the process of gradually increasing ozone concentration, the macromolecular organic matter is gradually broken into small molecular organic matter and degraded, while the small molecular organic matter that is difficult to remove through the ozone catalytic oxidation process or the organic matter that is not completely removed enters the activated carbon adsorption tank. Since the activated carbon has a large specific surface area and a developed pore structure, it can non-selectively adsorb the organic matter in the water; the present invention makes full use of the advantages of ozone catalytic oxidation and activated carbon adsorption processes, the two compensate each other, reduce the operating cost and improve the effluent water quality;

[0013] Second, in recent years, supported catalysts prepared by dispersing metals / metal oxides on catalytic carriers have gradually become the preparation trend of commercial catalytic materials. These composite materials not only overcome the agglomeration problem common in metal / metal oxide catalysts, but also stabilize the surface functional groups and structural defects of non-metallic materials, producing a synergistic effect. Manganese-based catalysts have achieved remarkable results in activating ozone. The manganese metal center will undergo a valence state conversion during the ozone oxidation process, which provides electrons for the conversion of ozone into free radicals, promotes the generation of reactive oxygen species (ROS), and thus achieves pollutant degradation.

[0014] 3. The method of the present invention is used to treat polluted water, wherein the removal rate of ammonia nitrogen can reach more than 80%, and the removal rate of COD can reach more than 75%. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process of the present invention. DETAILED DESCRIPTION

[0016] Specific implementation method 1: This implementation method is an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process, which is specifically completed according to the following steps:

[0017] 1. Introduce the reservoir raw water into the ozone catalytic oxidation tank, add the catalyst to the reservoir raw water, generate ozone through the ozone generator, control the ozone aeration device to continuously aerate the ozone catalytic oxidation tank, and carry out catalytic reaction under the action of the catalyst for a period of time to obtain the effluent after ozone catalytic oxidation;

[0018] Second, the effluent after ozone catalytic oxidation is introduced into the activated carbon adsorption tank, the activated carbon dosage is controlled by the activated carbon metering feeder, and the hydraulic retention reaction is carried out for a period of time to achieve the removal of macromolecular organic matter in the raw water, and the effluent after the reaction in the activated carbon adsorption tank is obtained;

[0019] 3. The effluent after the reaction in the activated carbon adsorption tank enters the filter to remove the activated carbon particles in the water. The filtered effluent is collected for subsequent deep treatment. The discarded activated carbon needs to be treated twice before discharge to avoid secondary pollution caused by direct discharge.

[0020] 4. Backwash water is introduced into the ozone catalytic oxidation tank and the activated carbon adsorption tank to use the shear force of the water flow and the collision friction of the particles to clean the dirt generated during the reaction process, thereby extending the service life of the reaction device while ensuring the water quality of the effluent, and collecting the backwash water for secondary reuse.

[0021] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that the average ammonia nitrogen content of the reservoir raw water in step 1 is 1.5 mg / L to 2.5 mg / L, and the average COD content is 5 mg / L to 7 mg / L. The other steps are the same as those in specific implementation method 1.

[0022] Specific implementation method three: This implementation method is different from specific implementation method one or two in that: in step one, the dosage of ozone is calculated according to the volume of raw water in the reservoir, and the dosage of ozone is 0.5mg / L to 1.5mg / L; the catalytic reaction time in the ozone catalytic oxidation tank in step one is 10min to 30min; the dosage of the catalyst in step one is 10mg / L to 70mg / L. The other steps are the same as those in specific implementation method one or two.

[0023] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the preparation method of the catalyst described in step 1 is specifically completed according to the following steps:

[0024] (1) Adding a NaS2O3 solution dropwise to a continuously stirred KMnO4 solution and leaving the solution to stand for a period of time; separating the precipitate using a centrifuge and washing it with ultrapure water, and then drying it in an oven for a period of time to obtain a dry product; transferring the dry product to a tube furnace, and then heating it to a calcination temperature under an argon atmosphere, and calcining it at the calcination temperature for a period of time, and the obtained product is MnO2;

[0025] (2) Dicyandiamide is used as a nitrogen source, mixed with MnO2, calcined for a period of time, and cooled to room temperature to obtain Mn3O4-CN, which is a catalyst. The other steps are the same as those in the first to third embodiments.

[0026] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that: the concentration of the KMnO4 solution in step (1) is 0.1 mol / L to 0.5 mol / L; the concentration of the NaS2O3 solution is 0.1 mol / L to 0.3 mol / L; the volume ratio of the KMnO4 solution to the NaS2O3 solution in step (1) is 1:2; the standing time in step (1) is 2h to 4h. The other steps are the same as those in specific embodiments 1 to 4.

[0027] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that: the temperature of the oven described in step (1) is 80°C to 120°C, and the drying time is 10h to 14h; the calcination temperature described in step (1) is 500°C, and the calcination time is 2h to 4h. The other steps are the same as those of specific embodiments 1 to 5.

[0028] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the molar ratio of dicyandiamide to MnO2 in step (2) is 1:(3-5); the calcination temperature in step (2) is 600°C-700°C, and the calcination time is 4h-6h. The other steps are the same as those in specific embodiments 1 to 6.

[0029] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that: the activated carbon described in step 2 is columnar granular carbon with a diameter of 1.5 mm, the flow rate of the activated carbon adsorption pool is 3 m / h to 5 m / h, and the thickness of the carbon layer is 0.5 m to 1 m; the time of the hydraulic retention reaction described in step 2 is 2 h to 4 h. The other steps are the same as those of specific embodiments 1 to 7.

[0030] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the secondary processing method described in step 3 is specifically completed according to the following steps:

[0031] The activated gas is introduced, and the waste activated carbon is first heated to 100°C to 150°C in the activated gas atmosphere, and heated at 100°C to 150°C for 1h to 2h to remove moisture and some low-boiling point organic matter; then the temperature is raised to 300°C to 700°C, and heated at 300°C to 700°C for 0.5h to 1h to thermally decompose the high-boiling point organic matter; then the temperature is heated to 700°C to 1000°C, and heated at 700°C to 1000°C for 0.5h to 1h to obtain regenerated activated carbon;

[0032] The activated gas is water vapor, carbon dioxide or oxygen. The other steps are the same as those in the first to eighth embodiments.

[0033] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that the amount of backwash water in step 4 is 10m 3 / (m 2 h), the pressure of backwash water is less than 0.15 MPa. The other steps are the same as those in the first to ninth embodiments.

[0034] The following examples are used to verify the beneficial effects of the present invention:

[0035] Example 1: An activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process is specifically completed according to the following steps:

[0036] 1. Introduce the reservoir raw water into the ozone catalytic oxidation tank, add the catalyst to the reservoir raw water, generate ozone through the ozone generator, control the ozone aeration device to continuously aerate the ozone catalytic oxidation tank, and carry out catalytic reaction under the action of the catalyst for a period of time to obtain the effluent after ozone catalytic oxidation;

[0037] The average ammonia nitrogen content of the reservoir raw water described in step 1 is 1.5 mg / L, and the average COD content is 5 mg / L;

[0038] In step 1, the ozone dosage is calculated based on the volume of raw water in the reservoir and is 0.8 mg / L;

[0039] The catalytic reaction time in the ozone catalytic oxidation tank in step 1 is 20 minutes;

[0040] The dosage of the catalyst in step 1 is 30 mg / L;

[0041] The preparation method of the catalyst described in step 1 is specifically completed according to the following steps:

[0042] (1) Adding a NaS2O3 solution dropwise to a continuously stirred KMnO4 solution and leaving the solution to stand for a period of time; separating the precipitate using a centrifuge and washing it with ultrapure water, and then drying it in an oven for a period of time to obtain a dry product; transferring the dry product to a tube furnace, and then heating it to a calcination temperature under an argon atmosphere, and calcining it at the calcination temperature for a period of time, and the obtained product is MnO2;

[0043] The concentration of the KMnO4 solution in step (1) is 0.3 mol / L; the concentration of the NaS2O3 solution is 0.2 mol / L;

[0044] The volume ratio of the KMnO4 solution to the NaS2O3 solution in step (1) is 1:2;

[0045] The standing time described in step (1) is 3 hours;

[0046] The temperature of the oven described in step (1) is 100° C. and the drying time is 10 h;

[0047] The calcination temperature in step (1) is 500° C. and the calcination time is 3 h;

[0048] (2) Dicyandiamide is used as a nitrogen source, mixed with MnO2, calcined for a period of time, and cooled to room temperature to obtain Mn3O4-CN, which is a catalyst;

[0049] The molar ratio of dicyandiamide to MnO2 in step (2) is 1:3;

[0050] The calcination temperature in step (2) is 650° C. and the calcination time is 4 h;

[0051] Second, the effluent after ozone catalytic oxidation is introduced into the activated carbon adsorption tank, the activated carbon dosage is controlled by the activated carbon metering feeder, and the hydraulic retention reaction is carried out for a period of time to achieve the removal of macromolecular organic matter in the raw water, and the effluent after the reaction in the activated carbon adsorption tank is obtained;

[0052] The activated carbon described in step 2 is columnar granular carbon with a diameter of 1.5 mm, the flow rate of the activated carbon adsorption pool is 3 m / h, and the thickness of the carbon layer is 0.6 m;

[0053] The time of the hydraulic retention reaction in step 2 is 3 hours;

[0054] 3. The effluent after the reaction in the activated carbon adsorption tank enters the filter to remove the activated carbon particles in the water. The filtered effluent is collected for subsequent deep treatment. The discarded activated carbon needs to be treated twice before discharge to avoid secondary pollution caused by direct discharge.

[0055] The secondary processing method described in step 3 is specifically completed by the following steps:

[0056] The activated gas is introduced, and the waste activated carbon is first heated to 100°C to 150°C in the activated gas atmosphere, and heated at 100°C to 150°C for 1h to 2h to remove moisture and some low-boiling point organic matter; then the temperature is raised to 300°C to 700°C, and heated at 300°C to 700°C for 0.5h to 1h to thermally decompose the high-boiling point organic matter; then the temperature is heated to 700°C to 1000°C, and heated at 700°C to 1000°C for 0.5h to 1h to obtain regenerated activated carbon;

[0057] The activated gas is water vapor, carbon dioxide or oxygen;

[0058] 4. Backwash water is introduced into the ozone catalytic oxidation and activated carbon adsorption tanks to use the shear force of the water flow and the collision friction of the particles to clean the dirt generated during the reaction process, thereby extending the service life of the reaction device while ensuring the quality of the effluent water, and collecting the backwash water for secondary reuse.

[0059] The amount of backwash water described in step 4 is 10m 3 / (m 2 ·h), the pressure of backwash water is less than 0.15MPa.

[0060] The average ammonia nitrogen content of the reservoir raw water described in step 1 in Example 1 is 1.5 mg / L, and the average COD content is 5 mg / L; after being treated by an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process in Example 1, the ammonia nitrogen content in the effluent is 0.3 mg / L, and the COD content is 1.3 mg / L. The ammonia nitrogen content in the effluent is <0.5 mg / L, and the COD content is <2 mg / L, which meets the national drinking water quality standards.

[0061] Comparative Example 1: The difference between this example and Example 1 is that the addition of catalyst to the reservoir raw water is omitted in step 1. The other steps and parameters are the same as those in Example 1.

[0062] The average ammonia nitrogen content of the reservoir raw water described in step 1 in comparative example 1 is 1.5 mg / L, and the average COD content is 5 mg / L; after being treated by an activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process in comparative example 1, the ammonia nitrogen content in the effluent is 0.8 mg / L, and the COD content is 2.2 mg / L.

[0063] In summary, compared with the ozone oxidation degradation efficiency in a pure ozone system, the degradation efficiency is significantly improved after adding Mn3O4-CN catalyst.

Claims

1. An activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process, characterized in that The pretreatment process is specifically completed according to the following steps:

1. Introduce the reservoir raw water into the ozone catalytic oxidation tank, add the catalyst to the reservoir raw water, generate ozone through the ozone generator, control the ozone aeration device to continuously aerate the ozone catalytic oxidation tank, and carry out catalytic reaction under the action of the catalyst for a period of time to obtain the effluent after ozone catalytic oxidation; Second, the effluent after ozone catalytic oxidation is introduced into the activated carbon adsorption tank, the activated carbon dosage is controlled by the activated carbon metering feeder, and the hydraulic retention reaction is carried out for a period of time to achieve the removal of macromolecular organic matter in the raw water, and the effluent after the reaction in the activated carbon adsorption tank is obtained; 3. The effluent after the reaction in the activated carbon adsorption tank enters the filter to remove the activated carbon particles in the water. The filtered effluent is collected for subsequent deep treatment. The discarded activated carbon needs to be treated twice before discharge to avoid secondary pollution caused by direct discharge.

4. Backwash water is introduced into the ozone catalytic oxidation tank and the activated carbon adsorption tank to use the shear force of the water flow and the collision friction of the particles to clean the dirt generated during the reaction process, thereby extending the service life of the reaction device while ensuring the water quality of the effluent, and collecting the backwash water for secondary reuse.

2. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that The average ammonia nitrogen content of the reservoir raw water described in step 1 is 1.5 mg / L to 2.5 mg / L, and the average COD content is 5 mg / L to 7 mg / L.

3. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that In step one, the dosage of ozone is calculated according to the volume of raw water in the reservoir, and is 0.5 mg / L to 1.5 mg / L; the catalytic reaction time in the ozone catalytic oxidation tank in step one is 10 min to 30 min; the dosage of the catalyst in step one is 10 mg / L to 70 mg / L.

4. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that The preparation method of the catalyst described in step 1 is specifically completed according to the following steps: (1) Adding a NaS2O3 solution dropwise to a continuously stirred KMnO4 solution and leaving the solution to stand for a period of time; separating the precipitate using a centrifuge and washing it with ultrapure water, and then drying it in an oven for a period of time to obtain a dry product; transferring the dry product to a tube furnace, and then heating it to a calcination temperature under an argon atmosphere, and calcining it at the calcination temperature for a period of time, and the obtained product is MnO2; (2) Dicyandiamide is used as a nitrogen source, mixed thoroughly with MnO2, calcined for a period of time, and cooled to room temperature to obtain Mn3O4-CN, which is the catalyst.

5. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 4 is characterized in that The concentration of the KMnO4 solution described in step (1) is 0.1mol / L to 0.5mol / L; the concentration of the NaS2O3 solution is 0.1mol / L to 0.3mol / L; the volume ratio of the KMnO4 solution to the NaS2O3 solution described in step (1) is 1:2; the standing time described in step (1) is 2h to 4h.

6. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 4 is characterized in that The temperature of the oven described in step (1) is 80° C. to 120° C., and the drying time is 10 h to 14 h; the temperature of the calcination described in step (1) is 500° C., and the calcination time is 2 h to 4 h.

7. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 4 is characterized in that The molar ratio of dicyandiamide to MnO2 in step (2) is 1:(3-5); the calcination temperature in step (2) is 600°C-700°C, and the calcination time is 4h-6h.

8. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that The activated carbon described in step 2 is columnar granular carbon with a diameter of 1.5 mm, the flow rate of the activated carbon adsorption pool is 3m / h~5m / h, and the thickness of the carbon layer is 0.5m~1m; the time of the hydraulic retention reaction described in step 2 is 2h~4h.

9. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that The secondary processing method described in step 3 is specifically completed by the following steps: The activated gas is introduced, and the waste activated carbon is first heated to 100°C to 150°C in the activated gas atmosphere, and heated at 100°C to 150°C for 1h to 2h to remove moisture and some low-boiling point organic matter; then the temperature is raised to 300°C to 700°C, and heated at 300°C to 700°C for 0.5h to 1h to thermally decompose the high-boiling point organic matter; then the temperature is heated to 700°C to 1000°C, and heated at 700°C to 1000°C for 0.5h to 1h to obtain regenerated activated carbon; The activated gas is water vapor, carbon dioxide or oxygen.

10. The activated carbon adsorption coupled ozone catalytic oxidation water pretreatment process according to claim 1 is characterized in that The amount of backwash water described in step 4 is 10m 3 / (m 2 ·h), the pressure of backwash water is less than 0.15MPa.

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