Preparation method of modified zeolite filter material for simultaneously removing dissolved manganese and ammonia-nitrogen in surface water and application thereof

Abstract

The application discloses a preparation method of modified zeolite filter material for intensively removing dissolved manganese and ammonia nitrogen in surface water and application of the modified zeolite filter material, and aims at solving the problems that existing manganese removal processes cannot simultaneously remove manganese and ammonia nitrogen, and the cost of natural manganese sand is relatively high. The preparation method of the modified zeolite filter material comprises the following steps: firstly, sieving clinoptilolite; secondly, immersing the sieved clinoptilolite in a dilute nitric acid solution; thirdly, placing the initial zeolite in a divalent manganese salt solution with a concentration of 0.2-0.5 mol / L to perform oscillation adsorption treatment; and fourthly, immersing the zeolite particles with adsorbed divalent manganese in a mixed solution of permanganate and sodium hydroxide to perform adsorption reaction, and then washing and drying to obtain the modified zeolite filter material. The modified zeolite filter material is used as filter material for surface water treatment, can quickly and effectively remove the two pollutants of manganese and ammonia nitrogen, and the removal rate of manganese ions in water can reach 95%, and the removal rate of ammonia nitrogen can reach more than 90%.

Description

Technical Field

[0001] This invention relates to a method for preparing modified zeolite filter media, and a method for treating wastewater containing dissolved manganese and ammonia nitrogen using the modified zeolite filter media. Background Technology

[0002] Manganese is a common transition metal element in geology, and its abundance is significant. Surface water often contains excessive dissolved manganese, posing a threat to drinking water safety. Long-term excessive manganese intake can cause adverse symptoms such as fatigue, dizziness, and memory decline, and may even affect children's intellectual development. Therefore, it is necessary to develop a cost-effective and efficient method for manganese removal to address the problem of excessive manganese ion levels in drinking water sources. Due to agricultural activities, industrial production, and daily life, ammonia nitrogen is gradually becoming a new pollutant in surface water, easily leading to the proliferation of algae and causing serious biological pollution problems. Eutrophication of water bodies reduces the effectiveness of traditional manganese removal processes and also leads to seasonal manganese pollution.

[0003] Currently, the most common manganese removal technology is aeration contact oxidation filtration, which oxidizes dissolved manganese in water into manganese-based activated filter membranes through aeration. These activated filter membranes have the effect of contact oxidation to remove manganese. However, the activated filter membranes have a long maturation period, weak activity, and unstable manganese removal effect. Insufficient manganese sand production and high cost also limit the promotion of this technology.

[0004] Manganese removal from surface water often employs chemical oxidation, with potassium permanganate and sodium hypochlorite being common oxidants. However, controlling the dosage of potassium permanganate is difficult; insufficient dosage leads to excessive manganese levels in the effluent, while excessive dosage causes color changes. Chlorine alone is ineffective for manganese removal due to low oxidation efficiency, requiring actual chlorine dosages exceeding the theoretical stoichiometric ratio (1.3 mg), and resulting in prolonged oxidation times. Therefore, given the limitations of existing technologies and the current state of water pollution, a practical and feasible treatment process needs to be proposed to achieve the simultaneous removal of both pollutants. Summary of the Invention

[0005] The purpose of this invention is to solve the problems that existing manganese removal processes cannot simultaneously remove both manganese and ammonia nitrogen pollutants, and that natural manganese sand is expensive. The invention provides a method for preparing modified zeolite filter media that enhances the simultaneous removal of dissolved manganese and ammonia nitrogen from surface water, and its application.

[0006] The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to the present invention is implemented according to the following steps:

[0007] First, the clinoptilolite is sieved to obtain clinoptilolite with a particle size of 0.8–1.2 mm.

[0008] 2. The screened clinoptilolite is washed and dried, then impregnated in dilute nitric acid solution, and then washed and dried again to obtain the initial zeolite.

[0009] 3. The initial zeolite was placed in a divalent manganese salt solution with a concentration of 0.2-0.5 mol / L for oscillation and adsorption treatment, and zeolite particles adsorbed with divalent manganese were separated.

[0010] IV. Under oscillation conditions, zeolite particles adsorbed with divalent manganese are immersed in a mixed solution of permanganate and sodium hydroxide, and heated in a water bath at 50-70°C for 10-16 hours to carry out the adsorption reaction. After washing and drying, modified zeolite filter media is obtained.

[0011] In step four, the concentration of sodium hydroxide in the mixed solution of potassium permanganate and sodium hydroxide is 0.3–0.6 mol / L, and the concentration of permanganate is 0.15–0.3 mol / L.

[0012] The application of modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water in this invention involves using the modified zeolite filter media as the filter medium and quartz sand as the support layer. Water containing dissolved manganese and ammonia nitrogen flows from top to bottom through the filter media for filtration.

[0013] This invention provides a method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water, and its application. Manganese oxides are loaded onto the surface of clinoptilolite under alkaline conditions via water bath heating. The filter media surface contains abundant hydroxyl functional groups and Mn-O-Mn structures, and is negatively charged, allowing for effective adsorption of metal cations and ammonium ions from the water through chemical bonding and electrostatic interactions. Sodium hypochlorite added before filtration effectively oxidizes the adsorbed dissolved manganese and ammonium ions under the catalytic action of the manganese oxides on the zeolite surface. The oxidized manganese ions are converted into trivalent and tetravalent manganese oxides, and the ammonium ions are oxidized to nitrate. The newly generated manganese oxides adhere to the filter media surface, achieving a filter media renewal process, continuing to adsorb manganese and ammonium ions, and catalyzing the oxidation of both pollutants by sodium hypochlorite, thus achieving green, circular pollutant removal without causing secondary pollution.

[0014] The present invention relates to a method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water, and its application, which has the following beneficial effects:

[0015] 1. The preparation method of the modified zeolite filter media in this invention is simple and easy to implement. The construction of filter columns filled with modified zeolite filter media, filter tanks loaded with manganese zeolite, or filter pools loaded with manganese zeolite is easy to implement and achieves good denitrification and manganese removal effects.

[0016] 2. The water treatment method of the present invention can quickly and effectively remove two pollutants, manganese and ammonia nitrogen. The process is simple and can be applied to centralized water supply plants or made into an integrated device for treating rural groundwater. It is inexpensive, easy to use, and has broad application prospects in the water treatment industry.

[0017] 3. The modified zeolite filter media of the present invention can be applied to existing water plants and is easy to modify. It is only necessary to replace part or all of the original filter media of the water plant with the modified filter media and add a sodium hypochlorite dosing device before filtration to achieve pollutant removal.

[0018] 4. In the event of sudden water pollution, sodium hypochlorite can be added immediately to ensure drinking water safety. If the source water is not polluted, the addition of sodium hypochlorite can be suspended to save on reagent costs.

[0019] 5. The modified zeolite filter media prepared in this invention, combined with sodium hypochlorite pre-oxidation, can achieve a manganese ion removal rate of 95% and an ammonia nitrogen removal rate of over 90% in water. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the operation of the modified zeolite filter column used in the embodiment to enhance the simultaneous removal of dissolved manganese and ammonia nitrogen from surface water;

[0021] Figure 2 The images shown are actual photos of the surface color changes of the modified zeolite filter media before and after operation under chlorination conditions in the application example. The left image shows the modified zeolite filter media before operation, and the right image shows the modified zeolite filter media after one week of operation. After long-term operation, the surface color of the filter media is significantly darker, and new manganese oxides are loaded on the surface of the filter media.

[0022] Figure 3 This is a graph showing the dissolved manganese removal rate test results of different application embodiments running continuously for 7 days in the application examples;

[0023] Figure 4 The graph shows the ammonia nitrogen removal rate test results of different application embodiments running continuously for 7 days in the application examples. Detailed Implementation

[0024] Specific Implementation Method 1: The preparation method of modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water in this implementation method is carried out according to the following steps:

[0025] First, the clinoptilolite is sieved to obtain clinoptilolite with a particle size of 0.8–1.2 mm.

[0026] 2. The screened clinoptilolite is washed and dried, then impregnated in dilute nitric acid solution, and then washed and dried again to obtain the initial zeolite.

[0027] 3. The initial zeolite was placed in a divalent manganese salt solution with a concentration of 0.2-0.5 mol / L for oscillation and adsorption treatment, and zeolite particles adsorbed with divalent manganese were separated.

[0028] IV. Under oscillation conditions, zeolite particles adsorbed with divalent manganese are immersed in a mixed solution of permanganate and sodium hydroxide, and heated in a water bath at 50-70°C for 10-16 hours to carry out the adsorption reaction. After washing and drying, modified zeolite filter media is obtained.

[0029] In step four, the concentration of sodium hydroxide in the mixed solution of potassium permanganate and sodium hydroxide is 0.3–0.6 mol / L, and the concentration of permanganate is 0.15–0.3 mol / L.

[0030] The zeolite described in step one of this embodiment has a particle size of 0.8–1.2 mm, a uniformity coefficient of 1.4–1.6, and a density of 2.2 g / cm³. 3 .

[0031] In this embodiment, the modified zeolite filter media is prepared by loading manganese dioxide onto the surface of zeolite under alkaline water bath heating conditions.

[0032] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the volume fraction of nitric acid in the dilute nitric acid solution in step two is 5% to 6%.

[0033] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the divalent manganese salt solution in step 3 is a manganese sulfate solution with a concentration of 0.3 mol / L.

[0034] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that a shaking table is used in step three for oscillation adsorption treatment, and the shaking table speed is controlled at 50 to 500 r / min, and the amplitude is 10 to 30 mm.

[0035] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the oscillation adsorption treatment time in step 3 is 10 to 16 hours.

[0036] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the molar ratio of sodium hydroxide to permanganate in the mixed solution of permanganate and sodium hydroxide described in step four is 2:1.

[0037] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the adsorption reaction is carried out in step four by heating in a water bath at 60°C for 12 hours.

[0038] Specific Implementation Method 8: This implementation method enhances the application of modified zeolite filter media for the simultaneous removal of dissolved manganese and ammonia nitrogen from surface water by using the modified zeolite filter media as the filter media and quartz sand as the support layer. Water containing dissolved manganese and ammonia nitrogen flows from top to bottom through the filter media for filtration.

[0039] This implementation method is applicable to surface water containing manganese and ammonia nitrogen, with a pH of 6.5 to 8.5.

[0040] This embodiment uses manganese-loaded zeolite particles as filter media and quartz sand as a support layer to construct manganese-loaded zeolite filter columns, filter tanks, or filter pools.

[0041] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Eight in that water containing dissolved manganese and ammonia nitrogen is pre-passed through a mixing tank. In the mixing tank, water containing dissolved manganese and ammonia nitrogen is mixed with sodium hypochlorite solution. The concentration of sodium hypochlorite in the system is 60-100 μM, and pre-oxidation treatment is carried out for 0.5-5 min.

[0042] Specific Implementation Method 10: This implementation method differs from Specific Implementation Method 8 or 9 in that water containing dissolved manganese and ammonia nitrogen flows from top to bottom through the filter media for filtration, and the contact time between the water containing dissolved manganese and ammonia nitrogen and the filter media is controlled to be 8 to 10 minutes.

[0043] Specific Implementation Method Eleven: This implementation method differs from Specific Implementation Methods Eight to Ten in that it uses modified zeolite filter media as the filter media, and the thickness of the filter media is 15-30cm.

[0044] Example 1: The preparation method of the modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water in this example is implemented according to the following steps:

[0045] 1. The clinoptilolite was sieved to obtain clinoptilolite with a particle size of 0.8–1.2 mm, a uniformity coefficient of 1.4–1.6, and a density of 2.2 g / cm³. 3 ;

[0046] 2. The screened clinoptilolite is washed and dried, and then immersed in dilute nitric acid solution to remove impurities and particulate matter on the surface of the filter material to facilitate subsequent loading. After washing and natural drying, the initial zeolite is obtained.

[0047] 3. The initial zeolite was placed in a 0.3 mol / L manganese sulfate solution for 6 hours of oscillation and adsorption treatment. The oscillation speed was controlled at 150 r / min and the amplitude was 20 mm. The mass-volume ratio of the initial zeolite to the divalent manganese salt solution was controlled at 1 kg / L. Zeolite particles adsorbed with divalent manganese were obtained by separation.

[0048] IV. Under oscillation conditions, zeolite particles adsorbed with divalent manganese were immersed in a mixed solution of potassium permanganate and sodium hydroxide and the adsorption reaction was carried out at 60°C for 12 hours. After washing with deionized water and air drying, modified zeolite filter media was obtained.

[0049] In step four, the concentration of sodium hydroxide in the mixed solution of potassium permanganate and sodium hydroxide is 0.4 mol / L, and the concentration of potassium permanganate is 0.2 mol / L.

[0050] Application Example 1: The application process of modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water in this example is as follows:

[0051] I. Constructing a filter column loaded with manganese zeolite:

[0052] The modified zeolite filter media prepared in Example 1 was used as the filter media, with a thickness of 20 cm. Quartz sand was used as the support layer to construct a manganese-loaded zeolite filter column.

[0053] II. Dynamic Filtering:

[0054] Water containing 1 mg / L dissolved manganese and 1 mg / L ammonia nitrogen enters the filter column filled with modified zeolite filter media from top to bottom. The contact time is 10 min to obtain filtered water. Before entering the filter column, the water passes through a mixing tank. Sodium hypochlorite solution is mixed with the raw water in the mixing tank for 3 min. The concentration of sodium hypochlorite is 80 μM. Then the water enters the filter column, and the influent flow rate is controlled at 2 mL / min.

[0055] In this embodiment, during the operation of the filter column filled with modified zeolite filter media, sodium hypochlorite solution is added to the front end, which effectively improves the removal efficiency of dissolved manganese and ammonia nitrogen. The removal rates of dissolved manganese and ammonia nitrogen are 95% and 93%, respectively, and the filter media can achieve the required effluent quality without a maturation period.

[0056] Application Example 2: The application process of the modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water in this example is as follows:

[0057] I. Constructing a filter column loaded with manganese zeolite:

[0058] The modified zeolite filter media prepared in Example 1 was used as the filter media, with a thickness of 20 cm. Quartz sand was used as the support layer to construct a manganese-loaded zeolite filter column.

[0059] II. Dynamic Filtering:

[0060] Water containing dissolved manganese and ammonia nitrogen enters from top to bottom into a filter column filled with modified zeolite filter media, with a contact time of 10 minutes, to obtain filtered water.

[0061] Application Example 3: The process of removing dissolved manganese and ammonia nitrogen from surface water using zeolite filter media in this example is as follows:

[0062] 1. Using clinoptilolite filter media as the filter medium, with a thickness of 20cm, and using quartz sand as the support layer, a manganese-loaded zeolite filter column is constructed.

[0063] II. Dynamic Filtering:

[0064] Water containing dissolved manganese and ammonia nitrogen enters from top to bottom into a filter column filled with modified zeolite filter media, with a contact time of 10 minutes, to obtain filtered water.

[0065] Application Example 4: The process of removing dissolved manganese and ammonia nitrogen from surface water using manganese sand filter media in this example is as follows:

[0066] 1. Constructing manganese-loaded zeolite filter columns using manganese sand as filter media and support layer;

[0067] II. Dynamic Filtering:

[0068] Water containing dissolved manganese and ammonia nitrogen enters from top to bottom into a filter column filled with modified zeolite filter media, with a contact time of 10 minutes, to obtain filtered water.

[0069] In Application Examples 2, 3, and 4, after the filter columns ran for 12 hours, 8 hours, and 3 hours respectively, the dissolved manganese and ammonia nitrogen content in the effluent exceeded the standards. Based on the removal efficiency of various filter media for dissolved manganese in water, it can be seen that without chlorine, simple zeolite has limited adsorption capacity for dissolved manganese and ammonia nitrogen; the modified zeolite filter media prepared in these examples has a good adsorption effect on dissolved manganese and ammonia nitrogen.

[0070] During initial operation, in Application Examples 1, 2, 3, and 4, when the contact time between the raw water and the filter column was 10 minutes, the dissolved manganese removal rates were 94%, 92%, 7%, and 92%, respectively, and the ammonia nitrogen removal rates were 95%, 82%, 8%, and 89%, respectively.

[0071] After one week of continuous operation, in Application Examples 1, 2, 3 and 4, when the contact time between the raw water and the filter column was 10 minutes, the dissolved manganese removal rates were 98%, 21%, 20% and 29%, respectively, and the ammonia nitrogen removal rates were 94%, 19%, 13% and 29%, respectively.

Claims

1. A method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water, characterized in that... The modified zeolite filter media is prepared according to the following steps: First, the clinoptilolite is sieved to obtain clinoptilolite with a particle size of 0.8–1.2 mm.

2. The screened clinoptilolite is washed and dried, then impregnated in dilute nitric acid solution, and then washed and dried again to obtain the initial zeolite.

3. The initial zeolite was placed in a divalent manganese salt solution with a concentration of 0.2-0.5 mol / L for oscillation and adsorption treatment, and zeolite particles adsorbed with divalent manganese were separated. IV. Under oscillation conditions, zeolite particles adsorbed with divalent manganese are immersed in a mixed solution of permanganate and sodium hydroxide, and heated in a water bath at 50-70°C for 10-16 hours to carry out the adsorption reaction. After washing and drying, modified zeolite filter media is obtained. In step four, the concentration of sodium hydroxide in the mixed solution of potassium permanganate and sodium hydroxide is 0.3–0.6 mol / L, and the concentration of permanganate is 0.15–0.3 mol / L.

2. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... In step two, the volume fraction of nitric acid in the dilute nitric acid solution is 5% to 6%.

3. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... In step three, the divalent manganese salt solution is a manganese sulfate solution with a concentration of 0.3 mol / L.

4. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... In step three, a shaking table is used for oscillation adsorption treatment, with the shaking table speed controlled at 50-500 r / min and the amplitude at 10-30 mm.

5. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... The oscillation adsorption treatment time in step three is 10–16 hours.

6. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... In step four, the molar ratio of sodium hydroxide to permanganate in the mixed solution of permanganate and sodium hydroxide is 2:

1.

7. The method for preparing modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 1, characterized in that... In step four, the adsorption reaction is carried out by heating in a water bath at 60°C for 12 hours.

8. The application of the modified zeolite filter media prepared as claimed in claim 1 for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water, characterized in that... The modified zeolite filter media is used as the filter medium, and quartz sand is used as the support layer. Water containing dissolved manganese and ammonia nitrogen flows from top to bottom through the filter media for filtration.

9. The application of the modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 8, characterized in that... Water containing dissolved manganese and ammonia nitrogen is pre-passed through a mixing tank. In the mixing tank, the water containing dissolved manganese and ammonia nitrogen is mixed with sodium hypochlorite solution. The concentration of sodium hypochlorite in the system is 60-100 μmol / L. Pre-oxidation treatment is carried out for 0.5-5 min.

10. The application of the modified zeolite filter media for enhanced simultaneous removal of dissolved manganese and ammonia nitrogen from surface water according to claim 8, characterized in that... Water containing dissolved manganese and ammonia nitrogen flows from top to bottom through the filter media for filtration. The contact time between the water containing dissolved manganese and ammonia nitrogen and the filter media is controlled to be 8 to 10 minutes.

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