System and method for removing high concentration ammonia nitrogen in water

Abstract

The present invention discloses a system for removing high-concentration ammonia nitrogen in water, comprising a storage and water supply unit, a pretreatment unit, a reaction treatment unit and a post-treatment unit connected in sequence; the storage and water supply unit is connected to raw water for storing raw water; the pretreatment unit is used to remove larger particulate matter in the raw water and adjust the pH value and temperature of the raw water; the reaction treatment unit is filled with a cobalt-manganese modified molecular sieve filter material for removing ammonia nitrogen in the raw water and simultaneously intercepting the suspended matter remaining in the water; the post-treatment unit is used to kill pathogenic microorganisms in the raw water after being treated by the reaction treatment unit; the system also includes a backwashing unit and a filter material regeneration unit connected to the reaction treatment unit, which are used for backwashing and regenerating the filter material, respectively. The present invention also discloses a method for removing ammonia nitrogen in water using the above system. The system of the present invention can effectively remove ammonia nitrogen in water with a concentration of ≤4 mg / L for a long time.

Description

Technical Field

[0001] The present invention belongs to the technical field of water treatment, and in particular relates to a system for removing high-concentration ammonia nitrogen in water. The present invention also relates to a method for removing ammonia nitrogen in water using the system. Background Art

[0002] Nitrogen-containing fertilizers used in large quantities in agricultural activities and manure discharged from livestock and poultry farming will enter water bodies through runoff or infiltration; urea and other nitrogen-containing compounds contained in domestic sewage decompose in natural water bodies; ammonia nitrogen in industrial wastewater comes from industries such as chemical, pharmaceutical and food processing. These sources of ammonia nitrogen have led to a continuous increase in the concentration of ammonia nitrogen in water bodies. High concentrations of ammonia nitrogen in water can lead to eutrophication of water bodies, excessive growth of algae, consumption of dissolved oxygen in water, deterioration of water quality, and problems such as the death of fish and other aquatic organisms. In addition, ammonia nitrogen can be converted into nitrite in the human body, which has the risk of carcinogenesis and mutagenesis and poses a threat to human health. High ammonia nitrogen content will also increase the difficulty and cost of water treatment, and improper treatment may cause harmful substances to remain in drinking water. Therefore, it is particularly important to find efficient, economical and environmentally friendly high ammonia nitrogen removal technology.

[0003] Domestic and foreign countries mainly use biological treatment methods (such as biofilters, fixed film reactors), nanomaterial methods (such as nano zero-valent iron (nZVI), nano titanium dioxide (TiO2)), photocatalytic technology, ion exchange, electrochemical methods and catalytic oxidation methods for high ammonia nitrogen treatment. Among the existing high ammonia nitrogen treatment methods, although the biological treatment method (such as biofilters, fixed film reactors) is simple to operate and has high removal efficiency, it has a long start-up time, requires regular maintenance, and has high requirements for operating conditions. Although the nanomaterial method (such as nano zero-valent iron (nZVI), nano titanium dioxide (TiO2)) can efficiently remove ammonia nitrogen from water, the production and application costs are high and regeneration is difficult. Although photocatalytic technology is environmentally friendly and effective in a broad spectrum, it has complex requirements for light sources, high energy consumption and complex maintenance. Although the ion exchange method is relatively simple to operate and manage and is suitable for water treatment systems of various sizes, it is complex to operate and the ion exchange resin is expensive, and it needs to be regenerated or replaced regularly. The electrochemical method can efficiently remove ammonia nitrogen from water without producing harmful byproducts, but the equipment is complex, the electrode material is expensive and needs to be replaced regularly. Although the catalytic oxidation method has a long service life, easy maintenance, and no secondary pollution, the catalyst is expensive and may become deactivated during use, requiring regular replacement or regeneration. Summary of the invention

[0004] The purpose of the present invention is to provide a system for removing high-concentration ammonia nitrogen in water, which can effectively remove ammonia nitrogen in water with a concentration of ≤4 mg / L for a long time.

[0005] Another object of the present invention is to provide a method for removing ammonia nitrogen from water using the above system.

[0006] The technical solution adopted by the present invention is:

[0007] A system for removing high-concentration ammonia nitrogen in water comprises a storage and water supply unit, a pretreatment unit, a reaction treatment unit and a post-treatment unit which are connected in sequence; the storage and water supply unit is connected to raw water and is used to store raw water; the pretreatment unit is used to remove larger particulate matter in the raw water and adjust the pH value and temperature of the raw water; the reaction treatment unit is filled with cobalt-manganese modified molecular sieve filter material, which is used to remove ammonia nitrogen in the raw water and simultaneously intercept the suspended matter remaining in the water; the post-treatment unit is used to kill pathogenic microorganisms in the raw water after being treated by the reaction treatment unit; the system also comprises a backwashing unit and a filter material regeneration unit connected to the reaction treatment unit, which are used to backwash and regenerate the cobalt-manganese modified molecular sieve filter material respectively.

[0008] The present invention is also characterized in that:

[0009] The storage and water supply unit includes a storage tank, a water supply pump and a flow meter connected in sequence; the storage tank is connected to the raw water and is used to store the raw water; the water supply pump is used to transport the raw water from the storage tank to the pretreatment unit; the flow meter is used to monitor and adjust the raw water flow entering the pretreatment unit.

[0010] The pretreatment unit includes a coarse filter and an adjusting tank which are connected in sequence. The coarse filter is connected to the storage and water supply unit. The coarse filter is a sand filter or a mesh filter with a filtration accuracy of 50-100mm, which is used to remove larger particle impurities in the raw water. The adjusting tank is used to adjust the temperature and pH value of the raw water, and it includes a tank body, a stirring mechanism and a pH adjusting mechanism. The pH adjusting mechanism is a dosing pump for hydrochloric acid or sodium hydroxide with a flow rate of 0.1-1L / h. An overflow pipe is arranged on the upper part of the adjusting tank, and valves are arranged on the inlet and outlet pipes and the overflow pipe of the adjusting tank.

[0011] The reaction treatment unit includes a reactor connected to the pretreatment unit through a pipeline, the reactor is filled with cobalt-manganese modified molecular sieve filter material, and the filter layer thickness of the filter material is 1.1-1.5m; the top or water inlet end of the reactor is connected to a uniform water distribution device, which is used to evenly distribute water on the filter material in the reactor; the bottom or side of the reactor is also connected to an aeration device through a pipeline, the aeration device is a disc aerator, the bubble diameter of which is between 2-4mm, and the aeration device is connected to an air pump.

[0012] The post-processing unit includes a fine filter and a disinfection device which are connected in sequence, the fine filter is connected to the reaction processing unit; the fine filter is an activated carbon filter with a filtration accuracy of 1-5 μm; the disinfection device is a chlorine disinfector, and the type of the disinfectant is liquid chlorine, sodium hypochlorite or chlorine tablet solution, and the mass percentage concentration of the solution is 0.5%-1%.

[0013] The backwash unit includes a water suction well and a backwash water pump connected in sequence, and also includes an air pressurizing device. The backwash water pump and the air pressurizing device are both connected to the reaction treatment unit through pipelines; the backwash water pump is used to suck out water from the water suction well and send it to the filter material in the reaction treatment unit to provide backwash water; the air pressurizing device is used to provide backwash air to the filter material.

[0014] The filter material regeneration unit comprises a drug storage mechanism and a drug adding mechanism which are connected in sequence. The drug adding mechanism is connected to the filter material in the reaction processing unit through a pipeline. An oxidant is placed in the drug storage mechanism. The drug adding mechanism adds the oxidant in the drug storage mechanism to the filter material in the reaction processing unit. The oxidant is a hydrogen peroxide solution with a mass percentage concentration of 1%-3% or a sodium persulfate solution with a mass percentage concentration of 0.5%-2%.

[0015] The preparation process of cobalt-manganese modified molecular sieve filter material is as follows:

[0016] First, the molecular sieve was alkaline pretreated with a 0.5 mol / L sodium hydroxide solution for 6 hours, and then the molecular sieve was rinsed with flowing deionized water until its pH value returned to neutral. Finally, the neutralized molecular sieve was immersed in a mixed solution of 0.5 mg / L cobalt chloride solution, 1 mg / L manganese chloride solution and 0.75 mg / L potassium ferrate solution. After soaking for 21 days, a cobalt-manganese modified molecular sieve filter material was obtained.

[0017] Another technical solution adopted by the present invention is:

[0018] The method for removing high concentration ammonia nitrogen in water uses the above removal system and is implemented in the following steps:

[0019] The raw water enters the pretreatment unit after passing through the storage and water supply unit. The pretreatment unit removes larger particulate matter in the water and adjusts the pH value and temperature of the raw water. The raw water then flows into the reaction treatment unit. Under the action of the cobalt-manganese modified molecular sieve filter material in the reaction treatment unit, ammonia nitrogen in the water is removed. The raw water then enters the post-treatment unit for sterilization and disinfection to obtain drinking water of qualified quality. In addition, the cobalt-manganese modified molecular sieve is backwashed and regenerated by air and water using the backwash unit and the filter material regeneration unit.

[0020] Another technical solution of the present invention is also characterized in that:

[0021] The filter layer thickness of the cobalt-manganese modified molecular sieve filter material is 1.1-1.5m, the filtration rate is 5-10m / h, and the filtration cycle is 1-2d; during air-water backwashing, the air impact intensity is 10-15L / (m 2 .s), air flushing was performed every 14 days, and each air flushing lasted for 10 minutes; the water flushing intensity was: the water flushing intensity was 6-8L / (m 2 . s), the water flushing intensity is 10-12L / (m 2 . s), flush with water every 7 days, each flush lasting 15 minutes.

[0022] The beneficial effects of the present invention are:

[0023] The system of the present invention adopts cobalt-manganese modified molecular sieve as filter material, utilizes its efficient chemical adsorption and contact catalytic oxidation performance, combines pretreatment and post-treatment units, and through backwashing and regeneration, realizes long-term effective removal of high-concentration (≤4mg / L) ammonia nitrogen in water, with high removal efficiency (ammonia nitrogen removal rate of about 91%) and fast processing speed (effective removal at a filtration rate of 5-10m / h). The system of the present invention has the advantages of simple operation, green environmental protection, strong adaptability and high economic benefits. It can efficiently adsorb and catalytically oxidize ammonia nitrogen, operate stably for a long time, without secondary pollution, easy maintenance, save resources, and is suitable for a variety of water quality conditions. It comprehensively improves water quality and ensures drinking water safety.

[0024] The system of the present invention is not only suitable for the design of new water supply plants, but also easy to realize the upgrading and transformation of existing water supply plants. In terms of the upgrading and transformation of existing water supply plants, it is only necessary to replace all or part of the existing filter materials in the filter tank with the cobalt-manganese modified molecular sieve of the present invention, so as to effectively improve the removal effect of high-concentration ammonia nitrogen in water and ensure the water quality of the effluent. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the system of the present invention;

[0026] Figure 2 It is a detailed structural diagram of the system of the present invention;

[0027] Figure 3 A curve diagram showing the change of ammonia nitrogen concentration with the operation time in an embodiment of the present invention;

[0028] Figure 4 is a curve diagram showing the change of the concentration of nitrogen with the operation time in the embodiment of the present invention;

[0029] Figure 5 The scanning electron microscope (SEM) images of the cobalt-manganese modified molecular sieve filter material before and after the reaction in the embodiment of the present invention are shown;

[0030] Figure 6 The energy spectrum analysis (EDS) diagram of the cobalt-manganese modified molecular sieve filter material before and after the reaction in the embodiment of the present invention;

[0031] Figure 7The X-ray photoelectron spectroscopy (XPS) diagram of the cobalt-manganese modified molecular sieve filter material before and after the reaction in the embodiment of the present invention;

[0032] Figure 8 The X-ray diffraction (XRD) diagram of the cobalt-manganese modified molecular sieve filter material before and after the reaction in the embodiment of the present invention.

[0033] In the figure, 1. storage and water supply unit, 11. storage tank, 12. water supply pump, 13. flow meter;

[0034] 2. Pretreatment unit, 21. Coarse filter, 22. Regulating tank, 23. Overflow pipe;

[0035] 3. Reaction treatment unit, 31. Reactor, 32. Uniform water distribution device, 33. Aeration device, 34. Air pump;

[0036] 4. post-processing unit, 41. fine filter, 42. disinfection device;

[0037] 5. Backwash unit, 51. Water suction well, 52. Backwash water pump, 53. Air pressurizing device;

[0038] 6. Filter material regeneration unit, 61. Drug storage mechanism, 62. Drug adding mechanism. DETAILED DESCRIPTION

[0039] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0040] The high-concentration ammonia nitrogen removal system of the present invention can effectively remove ammonia nitrogen with a concentration of ≤4 mg / L in water. The structure of the system is as follows: Figure 1 and Figure 2 As shown, it includes a storage and water supply unit 1, a pretreatment unit 2, a reaction treatment unit 3 and a post-treatment unit 4 connected in sequence. In addition, the reaction treatment unit 3 is also connected to a backwash unit 5 and a filter material regeneration unit 6. The storage and water supply unit 1 is connected to the raw water, and is used to store raw water containing high concentrations of ammonia nitrogen; the pretreatment unit 2 is used to remove larger particulate matter in the water, and adjust the pH value and temperature of the raw water to prevent clogging of the subsequent treatment unit, and make the pH value and temperature of the raw water meet the requirements of the subsequent treatment unit; the reaction treatment unit 3 is filled with a cobalt-manganese modified molecular sieve filter material, which has adsorption and catalytic oxidation capabilities, realizes contact catalytic oxidation of ammonia nitrogen in the water on the surface of the active oxidation film of the filter material, and at the same time intercepts the suspended matter remaining in the water; the post-treatment unit 4 is used to kill pathogenic microorganisms in the raw water treated by the reaction treatment unit 3, and finally produces qualified drinking water. In addition, the backwash unit 5 and the filter material regeneration unit 6 are used to backwash and regenerate the cobalt-manganese modified molecular sieve filter material in the reaction treatment unit 3, respectively.

[0041] like Figure 2As shown, the storage and water supply unit 1 includes a storage tank 11, a water supply pump 12 and a flow meter 13 connected in sequence; the storage tank 11 is connected to the raw water and is used to store the raw water containing a high concentration of ammonia nitrogen. The water supply pump 12 is used to transport the raw water from the storage tank 11 to the pretreatment unit 2, and monitor and adjust the raw water flow entering the pretreatment unit 2 through the flow meter 13.

[0042] The pretreatment unit 2 includes a coarse filter 21 and a regulating tank 22 connected in sequence. The coarse filter 21 is connected to the flow meter 13. The coarse filter 21 is a sand filter or a mesh filter with a filtration accuracy of 50-100mm and a flow rate of 10-15m / h. The regulating tank 22 includes a tank body, a stirring mechanism and a pH regulating mechanism. The tank body capacity is 0.5-1m 3 , the tank body material is anti-corrosion materials such as polyethylene; the stirring mechanism is a mechanical stirrer or a gas stirrer, and its power is 0.5-1.5kW; the pH adjustment mechanism is a dosing pump of hydrochloric acid (HCl) or sodium hydroxide (NaOH), and its flow rate is 0.1-1L / h. Under the action of the water supply pump 12, the raw water enters the coarse filter 21 through the pipeline. The coarse filter 21 removes the larger particle impurities in the raw water to prevent clogging of the subsequent treatment unit, and then enters the regulating tank 22. The regulating tank 22 is used to stabilize the water quality parameters of the raw water, provide the best water inlet conditions for the subsequent treatment unit, and adjust the temperature and pH value of the raw water to meet the best operating conditions of the subsequent treatment unit. An overflow pipe 23 is provided on the upper part of the regulating tank 22 to discharge excess water and prevent the water in the regulating tank 22 from overflowing. Valves are provided on the inlet and outlet pipes of the regulating tank 22 and the overflow pipe 23 to control the inlet and outlet and flow of water.

[0043] The reaction treatment unit 3 includes a reactor 31 connected to the regulating tank 22 by a pipeline, and the reactor 31 is filled with a cobalt-manganese modified molecular sieve filter material. The preparation process of the cobalt-manganese modified molecular sieve filter material is as follows: first, the molecular sieve is subjected to an alkali pretreatment with a 0.5 mol / L sodium hydroxide solution for 6 hours to increase the surface activity of the molecular sieve and improve its adsorption capacity for manganese ions; then the molecular sieve is rinsed with flowing deionized water until its pH value is restored to neutral to ensure the effectiveness of subsequent treatment; finally, the molecular sieve treated with neutralization is immersed in a mixed solution of 0.5 mg / L cobalt chloride solution, 1 mg / L manganese chloride solution and 0.75 mg / L potassium ferrate solution, and after immersion for 21 days, a cobalt-manganese modified molecular sieve filter material is obtained. During the immersion process, by precisely controlling the concentration of the solution and the reaction conditions, it is ensured that the manganese ions are uniformly deposited on the surface of the molecular sieve and a stable manganese oxide layer is formed. The entire immersion process lasts for 21 days to ensure that the cobalt-manganese modified molecular sieve is fully mature and stable. The cobalt-manganese modified molecular sieve filter material prepared by this method has a mature active oxide film on its surface and has excellent physical, chemical and crystal stability, and can efficiently remove ammonia nitrogen from water. Under the action of the mature active oxide film on the surface of the filter material, chemical adsorption and contact catalytic oxidation of high ammonia nitrogen in water are achieved, turbidity, chromaticity, ammonia nitrogen in the water body are removed, and residual suspended matter in the water is intercepted at the same time; the filtration rate of the cobalt-manganese modified molecular sieve filter material is controlled within 5-10m / h, the filter layer thickness is controlled within 1.1-1.5m, and the filtration cycle is controlled within 1-2d.

[0044] The top or water inlet of the reactor 31 is connected with a uniform water distribution device 32, which is used to evenly distribute water on the filter material in the reactor 31 to prevent water short circuit and improve the treatment efficiency of the reactor; the bottom or side of the reactor 31 is also connected with an aeration device 33 through a pipeline. The aeration device 33 is a disc aerator, and its bubble diameter is between 2-4mm and the air supply per hour is 0.7-1.2m 3 The aeration device 33 is connected to an air pump 34 and is used to inject air or oxygen into the reactor to promote the oxidation reaction in the reactor.

[0045] The post-processing unit 4 includes a fine filter 41 and a disinfection device 42 connected in sequence, and the fine filter 41 is connected to the reactor 31. The fine filter 41 is an activated carbon filter with a filtration accuracy of 1-5μm, a filtration rate of 5-10m / h, a diameter of 0.5-1.0m, and a height of 1.5-2.0m. The disinfection device 42 is a chlorine disinfector, and the type of its disinfectant is liquid chlorine, sodium hypochlorite (NaClO) or chlorine tablets (such as chlorine dioxide tablets), the mass percentage concentration of the solution is 0.5%-1%, the dosage is 1-5mg / L, and the contact time is determined according to the raw water quality and treatment objectives. More than 30 minutes to ensure full contact and reaction to kill microorganisms. The water purified by the reactor 31 enters the fine filter 41 and the disinfection device 42 for further filtration and disinfection, and then flows to the municipal water supply system through a pipeline.

[0046] The backwash unit 5 includes a water absorption well 51 and a backwash water pump 52 connected in sequence, and also includes an air pressurizing device 53. The backwash water pump 52 and the air pressurizing device 53 are connected to the reactor 31 through pipelines. The backwash water pump 52 absorbs water from the water absorption well 51 and then sends the water to the reactor 31 to provide backwash water; the air pressurizing device 53 provides backwash air to the reactor 31. When performing air-water backwashing, the air flushing intensity is selected to be 10-15L / (m 2 . s), the air flushing intensity within this range can ensure that the airflow penetrates the pores of the molecular sieve. Air flushing is performed every 14 days, and each air flushing lasts for 10 minutes to completely clear the internal pores of the molecular sieve. The water flushing intensity is: the water flushing intensity is 6-8L / (m 2 . s), the water flushing intensity is 10-12L / (m 2 . s), the water flushing intensity within this range can effectively flush the ammonia nitrogen on the surface of the cobalt-manganese modified molecular sieve material. Water flushing is performed every 7 days, and each flushing lasts for 15 minutes to ensure sufficient cleaning. After the cobalt-manganese modified molecular sieve filter material is used to remove high ammonia nitrogen in water, attachments will form on the filter material surface and dirt will form in the filter material pores. Therefore, air-water backwashing and selecting appropriate backwashing parameters can achieve better backwashing effects, effectively remove the occupied adsorption sites on the molecular sieve surface, and enable it to continuously and efficiently adsorb ammonia nitrogen.

[0047] The filter material regeneration unit 6 includes a drug storage mechanism 61 and a drug adding mechanism 62 which are connected in sequence. The drug adding mechanism 62 is connected to the reactor 31 through a pipeline. An oxidant is placed in the drug storage mechanism 61. The drug adding mechanism 62 puts the oxidant in the drug storage mechanism 61 into the reactor 31, and uses the strong oxidizing effect of the oxidant to restore the original activity of the filter material and regenerate the filter material. The oxidant is a hydrogen peroxide solution with a mass percentage concentration of 1%-3% or a sodium persulfate solution with a mass percentage concentration of 0.5%-2%. Hydrogen peroxide has strong oxidizing properties and no harmful byproducts, reacts quickly, and has mild processing conditions (hydrogen peroxide can work effectively in a wide pH range and has low corrosiveness to equipment and filter materials). Sodium persulfate is a strong oxidant with excellent redox potential. It can effectively remove stubborn pollutants on the surface of filter media. It is mainly used for cobalt-manganese modified molecular sieves. When removing high ammonia nitrogen in water, it will form complex chain compounds, which will affect the removal efficiency. Sodium persulfate has a long reaction time in water and can continuously oxidize complex chain compounds. Sodium persulfate is relatively stable at room temperature, easy to store and transport, and highly safe to use. The dosage of oxidant is determined according to the amount of filter media, the type of oxidant and the regeneration requirements of the filter media. The regeneration time is generally 30-60 minutes to ensure that the agent is fully in contact with the filter media. The regeneration cycle can be controlled within 1-2 months.

[0048] Embodiment 1:

[0049] In the removal system and removal method of this embodiment:

[0050] The water supply pump 12 has a power of 1.5 kW and a maximum flow rate of 5 m 3 / h centrifugal pump; the stirring mechanism in the regulating tank 22 adopts a mechanical stirrer with a power of 1.0kW; the coarse filter 21 adopts a sand filter with a filtration accuracy of 75mm and a flow rate of 13m / h; the reactor 31 adopts a fixed bed reactor with a height of 1.5m and a diameter of 0.5m. The filling amount of the filter material in the reactor is 50 kg, the filtration rate is controlled at 7.5m / h, the filter layer thickness is controlled at 1.3m, and the filtration cycle is controlled at 2d; the aeration device 33 is a disc aerator with a bubble diameter of 3mm and an air supply of 1.1m per hour. 3 ; The fine filter 41 is an activated carbon filter with a filtration accuracy of 3μm, a filtration rate of 7.5m / h, a diameter of 0.75m and a height of 1.8m; the disinfection device 42 is a chlorine disinfector, and the type of its disinfectant is a mixed solution of liquid chlorine and sodium hypochlorite. The mass percentage concentration of liquid chlorine in the mixed solution is 0.5%, and the mass percentage concentration of sodium hypochlorite is 0.75%. The dosage is set to 3mg / L, and the actual dosage of disinfectant added is 0.015mg / L of liquid chlorine and 0.0225mg / L of sodium hypochlorite; the oxidant uses a sodium persulfate solution with a mass percentage concentration of 1.5%.

[0051] Air impact strength 13L / (m 2 . s), air flushing is performed every 14 days, and each air flushing lasts for 10 minutes. The water flushing intensity is: the water flushing intensity is 8L / (m 2 . s), the water flushing intensity is 11L / (m 2 . s), flush with water every 7 days, each flush lasting 15 minutes.

[0052] The above system and process parameters were used to remove ammonia nitrogen from water, where the influent concentration of ammonia nitrogen was 4 mg / L. The removal effect was as follows: Figure 3 As shown, it can be seen that after the water containing ammonia nitrogen is treated by the system of this embodiment, the effluent concentration of ammonia nitrogen reaches below 0.5 mg / L, and the effluent concentration meets the requirements of the "Sanitary Standard for Drinking Water" (GB 5749-2022). After the system has been running for 60 days, it still has a good removal effect on ammonia nitrogen, and the effluent concentration still meets the requirements of the water quality standard.

[0053] Embodiment 2:

[0054] The concentrations of ammonia nitrogen, nitrite nitrogen and nitric nitrogen in the effluent of Example 1 were tested, and the results were as follows: Figure 4 As shown, it can be seen that during the 60-day operation, the effluent concentration of ammonia nitrogen remained below 0.5 mg / L, indicating that the system has a continuous and efficient removal capacity for high-concentration (initial concentration 4 mg / L) ammonia nitrogen. The effluent concentration of nitrite nitrogen showed an upward trend in the first 10 days of operation, and after rising to a peak of 1.53 mg / L, it began to decline, and a small peak of 0.72 mg / L appeared again during the 30-40 days of operation, and finally stabilized at 0.15-0.2 mg / L. This trend of change shows that: in the initial stage, ammonia nitrogen is oxidized to nitrite nitrogen, resulting in an increase in nitrite nitrogen concentration. As the system runs, nitrite nitrogen is further oxidized to nitric nitrogen, and the concentration gradually decreases. Finally, the nitrite nitrogen concentration stabilizes at a low level, indicating that the system can maintain a low nitrite nitrogen concentration in long-term operation and has a good treatment effect. The effluent concentration of nitrate nitrogen dropped to 2.3 mg / L in the first 10 days of operation, then rose to 3.5 mg / L, then dropped to 3.15 mg / L during 30-40 days, and finally stabilized at close to 4 mg / L. This shows that the system has good nitrification in long-term operation and can effectively oxidize ammonia nitrogen and nitrite nitrogen into nitrate nitrogen, reflecting its efficient oxidation capacity.

[0055] The system of the present invention adopts optimized cobalt-manganese modified molecular sieve filter material, which shows higher removal efficiency and stability for ammonia nitrogen, can maintain a low nitrite nitrogen concentration and a stable nitrate nitrogen concentration for a long time, and ensure that the effluent water quality meets the drinking water standard.

[0056] Embodiment 3:

[0057] After the system of Example 1 was operated for 60 days, the cobalt-manganese modified molecular sieve filter material after the reaction was subjected to microscopic characterizations such as SEM, EDS, XPS, and XRD to verify the microstructure of the filter material after long-term operation in the system of the present invention and under the process parameters of the method of the present invention. The results are as follows:

[0058] (1) Figure 5 As shown, these are SEM images of the cobalt-manganese modified molecular sieve filter material before and after the reaction, wherein Figure a and Figure b are SEM images 100 times and 5000 times before the reaction, respectively, and Figure c and Figure d are SEM images 100 times and 5000 times after the reaction, respectively. It can be seen that the surface morphology of the cobalt-manganese modified molecular sieve filter material after 60 days of operation still shows a stable porous structure, without obvious pore blockage or structural collapse, and the microstructure still maintains good integrity and uniformity. Compared with before the reaction, the micropores and mesopores are still clearly visible, indicating that it has always had high physical stability in long-term operation.

[0059] (2) Figure 6 As shown, it is the EDS diagram of the cobalt-manganese modified molecular sieve filter material before and after the reaction. It can be seen that the element composition of the filter material surface remains basically stable after 60 days of operation. The cobalt and manganese elements are still evenly distributed on the filter material surface without obvious migration or loss. Compared with before the reaction, the relative content of the main elements remains stable, indicating that the filter material has always had good chemical stability during use.

[0060] (3) Figure 7 The figures are XPS graphs of the cobalt-manganese modified molecular sieve filter material before and after the reaction, where a and c are XPS graphs before the reaction, and b and d are XPS graphs after the reaction. It can be seen that after 60 days of operation, the surface chemical state of the cobalt-manganese modified molecular sieve filter material has not changed significantly, and the manganese element still mainly exists in the form of Mn (Ⅳ) and Mn (Ⅲ), while the cobalt element exists in the form of Co-Mn alloy and CoMn2O4 compound. This shows that the filter material has no significant redox reaction or surface passivation phenomenon during long-term use, further proving its chemical stability.

[0061] (4) Figure 8As shown, these are the XRD diagrams of the cobalt-manganese modified molecular sieve filter material before and after the reaction, where Figure a is the XRD diagram before the reaction and Figure b is the XRD diagram after the reaction. It can be seen that after 60 days of operation, the crystal phase structure of the cobalt-manganese modified molecular sieve filter material has not changed significantly. Compared with before the reaction, the crystal structure remains stable, and the peak shape and peak position are basically the same, proving that the filter material has good crystal stability in long-term operation and is not easily damaged by external conditions.

[0062] In summary, the analysis results of microscopic characterization methods such as SEM, EDS, XPS and XRD show that the cobalt-manganese modified molecular sieve filter material still maintains good physical, chemical and crystal stability after running for 60 days under the system and process parameters of the present invention. This characteristic enables it to continue to play an effective role in the long-term treatment of water bodies containing high ammonia nitrogen, ensuring that the effluent water quality is stable and meets the standards.

Claims

1. A system for removing high concentration ammonia nitrogen from water, characterized in that: The system comprises a storage and water supply unit (1), a pretreatment unit (2), a reaction treatment unit (3) and a post-treatment unit (4) which are connected in sequence; the storage and water supply unit (1) is connected to raw water and is used to store raw water; the pretreatment unit (2) is used to remove larger particulate matter in the raw water and adjust the pH value and temperature of the raw water; the reaction treatment unit (3) is filled with a cobalt-manganese modified molecular sieve filter material and is used to remove ammonia nitrogen in the raw water and simultaneously intercept the suspended matter remaining in the water; the post-treatment unit (4) is used to kill pathogenic microorganisms in the raw water after being treated by the reaction treatment unit (3); the system further comprises a backwashing unit (5) and a filter material regeneration unit (6) connected to the reaction treatment unit (3), which are used to backwash and regenerate the cobalt-manganese modified molecular sieve filter material respectively; The storage and water supply unit (1) comprises a storage tank (11), a water supply pump (12) and a flow meter (13) which are connected in sequence; the storage tank (11) is connected to raw water and is used to store the raw water; the water supply pump (12) is used to transport the raw water from the storage tank (11) to the pretreatment unit (2); the flow meter (13) is used to monitor and adjust the flow rate of the raw water entering the pretreatment unit (2); The pretreatment unit (2) comprises a coarse filter (21) and a regulating tank (22) which are connected in sequence, the coarse filter (21) being connected to the storage and water supply unit (1); the coarse filter (21) being a sand filter or a mesh filter having a filtering accuracy of 50-100 mm and being used to remove larger particle impurities in raw water; the regulating tank (22) being used to regulate the temperature and pH value of raw water, comprising a tank body, a stirring mechanism and a pH regulating mechanism, the pH regulating mechanism being a dosing pump for hydrochloric acid or sodium hydroxide having a flow rate of 0.1-1 L / h; an overflow pipe (23) being provided at the top of the regulating tank (22), and valves being provided on the inlet and outlet pipes of the regulating tank (22) and on the overflow pipe (23); The reaction treatment unit (3) comprises a reactor (31) connected to the pretreatment unit (2) via a pipeline, the reactor (31) being filled with cobalt-manganese modified molecular sieve filter material, the filter layer thickness of the filter material being 1.1-1.5 m; the top or water inlet end of the reactor (31) is connected with a uniform water distribution device (32), which is used to uniformly distribute water on the filter material in the reactor (31); the bottom or side of the reactor (31) is also connected with an aeration device (33) via a pipeline, the aeration device (33) being a disc aerator, the bubble diameter of which is between 2 and 4 mm, and the aeration device (33) is connected with an air pump (34); The preparation process of the cobalt-manganese modified molecular sieve filter material is as follows: First, the molecular sieve was alkaline pretreated with a 0.5 mol / L sodium hydroxide solution for 6 hours, and then the molecular sieve was rinsed with flowing deionized water until its pH value returned to neutral. Finally, the neutralized molecular sieve was immersed in a mixed solution of 0.5 mg / L cobalt chloride solution, 1 mg / L manganese chloride solution and 0.75 mg / L potassium ferrate solution. After soaking for 21 days, a cobalt-manganese modified molecular sieve filter material was obtained.

2. The system for removing high concentration ammonia nitrogen in water according to claim 1, characterized in that: The post-processing unit (4) comprises a fine filter (41) and a disinfection device (42) which are connected in sequence, and the fine filter (41) is connected to the reaction processing unit (3); the fine filter (41) is an activated carbon filter with a filtration accuracy of 1-5 μm; The disinfection device (42) is a chlorine disinfector, and the type of disinfectant is liquid chlorine, sodium hypochlorite or chlorine tablet solution, and the mass percentage concentration of the solution is 0.5%-1%.

3. The system for removing high concentration ammonia nitrogen in water according to claim 1, characterized in that: The backwash unit (5) comprises a water suction well (51) and a backwash water pump (52) which are connected in sequence, and also comprises an air pressurizing device (53); the backwash water pump (52) and the air pressurizing device (53) are both connected to the reaction treatment unit (3) through pipelines; the backwash water pump (52) is used to suck out water in the water suction well (51) and send it to the filter material in the reaction treatment unit (3) to provide backwash water; the air pressurizing device (53) is used to provide backwash air to the filter material.

4. The system for removing high concentration ammonia nitrogen in water according to claim 1, characterized in that: The filter material regeneration unit (6) comprises a drug storage mechanism (61) and a drug adding mechanism (62) which are connected in sequence, the drug adding mechanism (62) being connected to the filter material in the reaction processing unit (3) via a pipeline, an oxidant being placed in the drug storage mechanism (61), and the drug adding mechanism (62) adding the oxidant in the drug storage mechanism (61) to the filter material in the reaction processing unit (3), the oxidant being a hydrogen peroxide solution with a mass percentage concentration of 1% to 3% or a sodium persulfate solution with a mass percentage concentration of 0.5% to 2%.

5. A method for removing high concentration ammonia nitrogen in water, characterized in that: Using the system as described in any one of claims 1 to 4, the method is implemented in the following steps: The raw water passes through the storage and water supply unit (1) and enters the pretreatment unit (2). The pretreatment unit (2) removes larger particulate matter in the water and adjusts the pH value and temperature of the raw water. The raw water then flows into the reaction treatment unit (3). Under the action of the cobalt-manganese modified molecular sieve filter material in the reaction treatment unit (3), ammonia nitrogen in the water is removed. The raw water then enters the post-treatment unit (4) for sterilization and disinfection to obtain drinking water of qualified quality. In addition, the cobalt-manganese modified molecular sieve is backwashed with air and water and regenerated using the backwash unit (5) and the filter material regeneration unit (6).

6. The method for removing high concentration ammonia nitrogen in water according to claim 5, characterized in that: The filter layer thickness of the cobalt-manganese modified molecular sieve filter material is 1.1-1.5m, the filtration rate during filtration is 5-10m / h, and the filtration cycle is 1-2d; during air-water backwashing, the air impact intensity is 10-15L / (m 2. s), air flushing is performed every 14 days, and each air flushing lasts for 10 minutes; the water flushing intensity is: the water flushing intensity is 6-8L / (m 2. s), the water flushing intensity is 10-12L / (m 2. s), flush with water every 7 days, and each flush lasts for 15 minutes.

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