Preparation method of modified activated carbon adsorption material and application of the material in denitrification coupled with microorganisms

Abstract

The application relates to a preparation method of modified activated carbon adsorption material and application of the modified activated carbon adsorption material in coupling denitrification with microorganisms, and aims to solve the problems of large aeration amount, high denitrification energy consumption and poor denitrification effect in the existing denitrification process. The preparation method of the modified activated carbon adsorption material is as follows: I. high ferric acid salt is added into a phosphoric acid buffer solution, the pH of the system is adjusted to 7, and the high ferric acid salt is hydrolyzed to generate iron hydroxide through stirring; II. after standing for 2.5-4 hours, the supernatant is sucked and discarded, and the lower-layer iron hydroxide suspension is obtained; III. active carbon is filled in a filter column, the iron hydroxide suspension obtained in the step II is pumped into the filter column, and the pumping is circularly carried out until the filtrate is clear and free of precipitate, so that the modified activated carbon adsorption material is obtained. The preparation method of the soaking modified activated carbon adsorption material is to modify the active carbon through high ferric oxidation, the iron hydroxide particles can be loaded on the surface of the active carbon, the iron ammonia oxidation system is formed after domestication, and the conversion of ammonia nitrogen can be realized in an anaerobic environment without aeration.

Description

Technical Field

[0001] This invention belongs to the field of adsorption materials technology, specifically relating to the preparation method and application of modified activated carbon adsorption materials for nitrogen and phosphorus in domestic sewage. Background Technology

[0002] Excessive discharge of domestic sewage has a significant impact on aquatic ecosystems, environmental quality, and human health. The harmful effects of nitrogen and phosphorus on water bodies are mainly manifested in the following ways: nitrogen leads to eutrophication, causing algal blooms in lakes and red tides in seawater; the massive proliferation of algae drastically reduces dissolved oxygen in the water, leading to fish and shrimp mortality; the decomposition of biomass further exacerbates eutrophication, creating a vicious cycle; and the water gradually turns black and smelly, seriously affecting the safety of drinking water and the living environment of surrounding residents. Therefore, nitrogen removal from sewage is essential.

[0003] Nitrogen not only impacts environmental quality but also harms human health. How to remove nitrogen while reducing aeration volume has become a key research focus for scholars both domestically and internationally.

[0004] Traditional denitrification processes are stable and cost-effective, but require large aeration volumes and consume significant energy. The porous structure of activated carbon is generally designed for adsorbing trace amounts of organic matter, and its effectiveness in denitrification is minimal. Summary of the Invention

[0005] The purpose of this invention is to solve the problems of large aeration volume and high energy consumption in existing denitrification processes, and to provide a method for preparing modified activated carbon adsorbent materials and their application in denitrification coupled with microorganisms.

[0006] The preparation method of the hybrid modified activated carbon adsorbent material of the present invention is carried out according to the following steps:

[0007] 1. Add ferrate to phosphate buffer solution to adjust the pH of the system to 7, and stir continuously to hydrolyze the ferrate to produce ferric hydroxide, thus obtaining the reaction solution;

[0008] 2. After the ferrate in the reaction solution of step one has completely decomposed, let it stand for 2.5 to 4 hours, remove the supernatant and discard it to obtain the lower layer of ferric hydroxide suspension.

[0009] 3. The filter column is filled with activated carbon. The ferric hydroxide suspension obtained in step 2 is pumped into the filter column and circulated repeatedly until the filtrate is clear and free of precipitate, thus obtaining the modified activated carbon adsorbent material.

[0010] The preparation method of the mixed modified activated carbon adsorbent material of the present invention involves adding a certain proportion of ferric hydroxide, which can load ferric hydroxide particles on the surface of activated carbon, enrich the pore structure of the activated carbon surface, and form an iron ammonia oxidation system after acclimation. Ammonia nitrogen can be converted in an anaerobic environment without aeration.

[0011] The preparation method of the modified activated carbon adsorbent material of the present invention is carried out according to the following steps:

[0012] 1. Ferrate is added to phosphate buffer solution to obtain ferrate solution;

[0013] 2. Add activated carbon to the ferrate solution, mix and stir, adjust the pH of the system to 7 to completely hydrolyze the ferrate, let stand for 2.5-4 hours, remove the supernatant and discard it to obtain a solid-liquid mixture of ferric hydroxide and activated carbon.

[0014] 3. Load the solid-liquid mixture of ferric hydroxide and activated carbon into a filter column, and use a peristaltic pump to circulate and filter it until the filtrate is clear and free of ferric hydroxide precipitate. Stop the acclimation process to obtain the modified activated carbon adsorbent material.

[0015] The method for preparing the modified activated carbon adsorbent material of the present invention involves modifying activated carbon by high-iron oxidation, which enables the loading of iron hydroxide particles on the surface of the activated carbon. After acclimation, an iron-ammonia oxidation system is formed, which can realize the conversion of ammonia nitrogen in an anaerobic environment without the need for aeration.

[0016] The application of modified activated carbon adsorbent material coupled with microorganisms for denitrification in this invention involves loading the modified activated carbon adsorbent material into a filter column, circulating wastewater into the filter column, and during the wastewater circulation process, a biofilm grows on the surface of the modified activated carbon adsorbent material, thereby removing ammonia nitrogen pollutants from the wastewater. Attached Figure Description

[0017] Figure 1 This is a bar chart showing the conversion efficiency of ammonia nitrogen in the application examples;

[0018] Figure 2 This is a scanning electron microscope image of the surface of the original activated carbon.

[0019] Figure 3 This is a scanning electron microscope image of the modified activated carbon adsorbent material prepared in Example 1;

[0020] Figure 4 This is a scanning electron microscope image of the modified activated carbon adsorbent material prepared in Example 2;

[0021] Figure 5 This is a scanning electron microscope image of the modified activated carbon adsorbent material prepared in Example 3;

[0022] Figure 6 This is a scanning electron microscope image of the modified activated carbon adsorbent material prepared in Example 4. Detailed Implementation

[0023] Specific Implementation Method 1: The preparation method of the mixed modified activated carbon adsorbent material in this implementation method is carried out according to the following steps:

[0024] 1. Add potassium ferrate to the phosphate buffer solution to adjust the pH of the system to 7, and stir continuously to hydrolyze potassium ferrate to produce ferric hydroxide, thus obtaining the reaction solution;

[0025] 2. After the ferrate in the reaction solution of step one has completely decomposed, let it stand for 2.5 to 4 hours, remove the supernatant and discard it to obtain the lower layer of ferric hydroxide suspension.

[0026] 3. The filter column is filled with activated carbon. The ferric hydroxide suspension obtained in step 2 is pumped into the filter column and circulated repeatedly until the filtrate is clear and free of precipitate, thus obtaining the modified activated carbon adsorbent material.

[0027] In this embodiment, the preferred mass ratio of ferrate to activated carbon is 1:15-20.

[0028] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the ferrate mentioned in step one is sodium ferrate or potassium ferrate.

[0029] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that ferrate is added to the phosphate buffer solution in step 1, and the concentration of ferrate in the system is 1-3 g / L.

[0030] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that hydrochloric acid or sodium hydroxide is used to adjust the pH of the system to 7 in step one.

[0031] Specific Implementation Method 5: This implementation method differs from Specific Implementation Methods 1 to 4 in that the settling time in step 2 is 3 hours.

[0032] Specific Implementation Method Six: The preparation method of the impregnated modified activated carbon adsorbent material in this implementation method is carried out according to the following steps:

[0033] 1. Ferrate is added to phosphate buffer solution to obtain ferrate solution;

[0034] 2. Add activated carbon to the ferrate solution, mix and stir, adjust the pH of the system to 7 to completely hydrolyze the ferrate, let stand for 2.5-4 hours, remove the supernatant and discard it to obtain a solid-liquid mixture of ferric hydroxide and activated carbon.

[0035] 3. Load the solid-liquid mixture of ferric hydroxide and activated carbon into a filter column, and use a peristaltic pump to circulate and filter it until the filtrate is clear and free of ferric hydroxide precipitate. Stop the acclimation process to obtain the modified activated carbon adsorbent material.

[0036] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Method Six in that the concentration of ferrate in the ferrate solution in step one is 2 g / L.

[0037] Specific Implementation Method 8: This implementation method differs from Specific Implementation Method 6 or 7 in that the mass ratio of ferrate to activated carbon in step 2 is (1-2):(15-30).

[0038] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Six or Seven in that the settling time in step two is 3 to 4 hours.

[0039] Specific Implementation Method 10: In this implementation method, the modified activated carbon adsorbent material is coupled with microorganisms for denitrification. The modified activated carbon adsorbent material is loaded into a filter column, and sewage is circulated into the filter column. During the sewage circulation process, a biofilm grows on the surface of the modified activated carbon adsorbent material, thereby removing ammonia nitrogen pollutants from the sewage.

[0040] Example 1: The preparation method of the mixed modified activated carbon adsorbent material in this example is carried out according to the following steps:

[0041] 1. Add potassium ferrate to the phosphate buffer solution to adjust the pH of the system to 7. Stir continuously to hydrolyze the potassium ferrate to produce ferric hydroxide, and obtain 500 ml of reaction solution. The concentration of potassium ferrate in the reaction solution is 2 g / L.

[0042] 2. After the potassium ferrate in the reaction solution of step one has completely decomposed, let it stand for 3 hours, remove 300 ml of supernatant and discard it to obtain the lower layer of ferric hydroxide suspension.

[0043] 3. 15g of activated carbon is packed into the filter column. The ferric hydroxide suspension obtained in step 2 is pumped into the filter column and circulated repeatedly until the filtrate is clear and free of precipitate, thus obtaining the modified activated carbon adsorbent material.

[0044] The water treatment experiment mainly consists of: measuring the ammonia nitrogen content in the original sewage, sewage pretreatment, measuring the ammonia nitrogen content in the pretreated sewage, sewage flowing into the filter column for filtration, and measuring the ammonia nitrogen content in the water after filtration for 10 hours. The specific experimental procedure is as follows: (1) Sewage pretreatment: filter the sewage to remove insoluble large particles. Add 15 mg / L potassium ferrate solution (the solution passes through a 0.45 μm filter membrane), stir for 30 min, and then add 20 mg / L polyaluminum chloride for coagulation and sedimentation. The ammonia nitrogen concentration in the pretreated sewage is 50 mg / L. (2) Filtration experiment: pump the pretreated sewage into the filter column (the filter column is connected to the atmosphere) with modified activated carbon adsorption material using a peristaltic pump, circulate repeatedly, and take a sample after filtration for 10 hours. (3) Determination of ammonia nitrogen content: take 1 ml of water sample, add it to a 50 ml colorimetric tube, and dilute to the mark; add 1 ml of potassium sodium tartrate solution and mix well. Add 1 ml of Nathaniel's reagent and mix well. After standing for 10 minutes, the wavelength was measured using a 10 mm cuvette.

[0045] In this embodiment, the efficiency of the mixed modified activated carbon adsorbent material in absorbing and converting ammonia nitrogen (to nitrite and nitrate nitrogen) was 79.36%.

[0046] Example 2: This example differs from Example 1 in that step three involves filling the filter column with 30g of activated carbon.

[0047] In this embodiment, the absorption and conversion efficiency of ammonia nitrogen by the hybrid modified activated carbon adsorbent material was 50.45%.

[0048] Example 3: The preparation method of the impregnated modified activated carbon adsorbent material is carried out according to the following steps:

[0049] 1. Potassium ferrate was added to phosphate buffer solution to obtain 500 ml of potassium ferrate solution. The concentration of potassium ferrate in the potassium ferrate solution was 2 g / L.

[0050] 2. Add 15g of activated carbon to the potassium ferrate solution, mix and stir, adjust the pH of the system to 7 to completely hydrolyze the ferrate, let stand for 3 hours, remove 300ml of supernatant and discard it to obtain a solid-liquid mixture of ferric hydroxide and activated carbon.

[0051] 3. Load the solid-liquid mixture of ferric hydroxide and activated carbon into a filter column, and use a peristaltic pump to circulate and filter it until the filtrate is clear and free of ferric hydroxide precipitate. Stop the acclimation process to obtain the modified activated carbon adsorbent material.

[0052] In this embodiment, the absorption and conversion efficiency of the impregnated modified activated carbon adsorbent material for ammonia nitrogen was 30.45%.

[0053] Example 4: This example differs from Example 3 in that 30g of activated carbon is added to the potassium ferrate solution.

[0054] In this embodiment, the absorption and conversion efficiency of the impregnated modified activated carbon adsorbent material for ammonia nitrogen was 20.36%.

[0055] As shown in the above examples, the mixed-modified activated carbon has a higher conversion efficiency for ammonia nitrogen, and the amount of activated carbon required is not large. The lower the activated carbon content, the greater the number of biological units per volume, and the better the denitrification effect. SEM images show that the modified activated carbon has an increased number of pores, and the mixed modification effect is superior to the soaking modification. In Example 1, the modified activated carbon adsorbent showed the best microbial growth effect and the highest ammonia nitrogen conversion rate, with the optimal mass ratio of ferrate to activated carbon being 1:15.

Claims

1. The application of modified activated carbon adsorbent materials, characterized in that, Modified activated carbon adsorbent material is loaded into a filter column, and wastewater is circulated through the filter column. During the wastewater circulation process, a biofilm grows on the surface of the modified activated carbon adsorbent material, forming an iron-ammonia oxidation system, thereby removing ammonia nitrogen pollutants from the wastewater in an anaerobic environment without the need for aeration. The preparation method of the modified activated carbon adsorbent material is carried out according to the following steps:

1. Add ferrate to phosphate buffer solution to adjust the pH of the system to 7, and stir continuously to hydrolyze the ferrate to produce ferric hydroxide, thus obtaining the reaction solution; 2. After the ferrate in the reaction solution of step one has completely decomposed, let it stand for 2.5 to 4 hours, remove the supernatant and discard it to obtain the lower layer of ferric hydroxide suspension.

3. The filter column is filled with activated carbon. The ferric hydroxide suspension obtained in step 2 is pumped into the filter column and circulated repeatedly until the filtrate is clear and free of precipitate, thus obtaining the modified activated carbon adsorbent material.

2. The application of the modified activated carbon adsorbent material according to claim 1, characterized in that, The ferrate mentioned in step one is sodium ferrate or potassium ferrate.

3. The application of the modified activated carbon adsorbent material according to claim 1, characterized in that, In step one, ferrate is added to the phosphate buffer solution, and the concentration of ferrate in the system is 1~3 g / L.

4. The application of the modified activated carbon adsorbent material according to claim 1, characterized in that, In step one, the pH of the system is adjusted to 7 using hydrochloric acid or sodium hydroxide.

5. The application of the modified activated carbon adsorbent material according to claim 1, characterized in that, The settling time in step two is 3 hours.

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