Preparation method of composite material for recovering nitrogen and phosphorus in water body and simultaneously removing antibiotics

Abstract

The invention relates to the technical field of sewage treatment, in particular to a preparation method of a composite material for recovering nitrogen and phosphorus in a water body and simultaneously removing antibiotics. According to the composite material, iron-rich sludge carbon and straw biomass carbon are used as carriers, calcium peroxide is used as an additive substance, and the iron-rich sludge-straw-based mixed biomass carbon loaded calcium peroxide composite material is prepared through coupling under the action of an adhesive. The composite material prepared by the method has a rich pore structure and a relatively large specific surface area, calcium peroxide is loaded on pores and the surface, and nitrogen and phosphorus nutrient substances in a water body can be adsorbed and enriched and antibiotics can be efficiently degraded by means of surface adsorption and chemical action; the preparation method of the composite material is simple in process, convenient to operate, easily available in raw materials and easy for large-scale production; after being adsorbed and enriched, nitrogen and phosphorus nutrient substances in a water body can be recycled and applied to fertility improvement of barren soil.

Description

Technical Field

[0001] The present invention relates to the technical field of sewage treatment, and specifically to a preparation method of a composite material for recovering nitrogen and phosphorus in water bodies while removing antibiotics. Background Art

[0002] With the acceleration of the industrialization and urbanization processes, human production and life have led to a large amount of nitrogen, phosphorus, and antibiotics entering the natural water environment with the discharge of domestic sewage and industrial wastewater. Excessive nitrogen and phosphorus substances in the water environment can cause water eutrophication, leading to a large reproduction of phytoplankton, resulting in a rapid consumption of dissolved oxygen in the water body, further leading to water quality deterioration and damage to the water ecosystem, causing serious pollution to the environment; while the large enrichment of antibiotics can lead to the generation of resistance genes and antibiotic-resistant bacteria, posing a serious threat to human health. Therefore, sewage treatment is required. Most traditional water treatment processes use microbial combination processes to decompose or transform nitrogen and phosphorus in sewage, resulting in serious waste of this part of nitrogen and phosphorus resources. Nitrogen and phosphorus are the basic elements of the structure and function of organisms. In order to improve the utilization rate of nitrogen and phosphorus in sewage, for composite polluted water bodies, the present invention will seek new materials and new technologies for recovering nitrogen and phosphorus resources and simultaneously removing antibiotics, which has important significance and social needs.

[0003] As of 2020, the number of urban sewage treatment plants in China reached 2,679, and the number of sewage treatment plants is still showing an upward trend. The daily urban sewage treatment capacity reached 192 million cubic meters. When a sewage treatment plant treats 10,000 tons of domestic sewage, it can produce 5 - 8 tons of sludge with a moisture content of 80%. Then, 96,000 - 153,600 tons of sludge with a moisture content of 80% can be produced every day. Sludge is obviously the main by-product generated by urban sewage treatment plants, which has the dual attributes of resources and pollution. If not properly treated, it will cause secondary pollution to the environment. If the sludge is recycled, it can achieve "turning waste into treasure" and save a large amount of sludge treatment and disposal costs. Therefore, making sludge into an adsorption material with good performance for recovering nitrogen and phosphorus nutrients in wastewater meets the requirements of green development. Not only can the prepared composite material be applied to environmental pollution treatment, but the recovered product can also be applied to the fertility improvement of barren soils, achieving the multiple environmental protection concepts of "treating waste with waste + resource utilization".

[0004] Adsorption is a relatively mature water treatment method at present. It can not only physically adsorb and remove many hydrophobic toxic and harmful substances, but also chemically adsorb hydrophilic and ionic harmful substances. It is an efficient water treatment technology with advantages such as good treatment effect, simple process operation, easy installation and maintenance of treatment devices, and easy replacement and recycling of materials. Biochar has characteristics such as a rich pore structure, a large specific surface area, and abundant surface groups. It is a good adsorption material with the function of catalytic degradation. Reports have shown that biochar has good adsorption and oxidative degradation properties for dyes, phenolic compounds, ammonia nitrogen, and antibiotics in the water environment, but has almost no adsorption effect on phosphate. Therefore, this invention attempts to modify iron-rich sludge-based biochar and straw biomass char by loading an appropriate amount of calcium peroxide. The prepared composite material can realize the recovery of nitrogen and phosphorus in water and the simultaneous removal of antibiotics through physical adsorption and chemical degradation. The recovered composite can be reused as a soil conditioner for infertile soil. Among the currently published patented technologies, there is no report on the technology of using iron-rich sludge carbon-based composite materials to recover nitrogen and phosphorus nutrients in water and simultaneously remove antibiotics. Summary of the Invention

[0005] The purpose of the present invention is to provide a composite material for recovering nitrogen and phosphorus in water and simultaneously removing antibiotics. Specifically, it is to prepare a composite material of iron-rich sludge-straw-based mixed biomass char loaded with calcium peroxide. The iron-rich sludge carbon and straw biomass carbon in the composite material have a rich pore structure and a large specific surface area on their surfaces, and a large amount of calcium peroxide can be loaded in the pores and on the surface. Under the action of this composite material, nitrogen and phosphorus in water can be recovered quickly and efficiently, while antibiotics in sewage can be removed. Moreover, the recovered nitrogen phosphorus / composite material can be reused for improving the fertility of infertile soil. That is, the composite material has a high function of recovering nitrogen and phosphorus, and also has the function of simultaneously removing antibiotics. It has good application prospects in the field of composite water pollution treatment, and the material preparation process is simple, the raw materials are easy to obtain, and it is easy to scale up production.

[0006] In order to achieve the above purpose, the present invention provides the following technical solutions:

[0007] A composite material for recovering nitrogen and phosphorus in water and simultaneously removing antibiotics, the composite material is specifically a composite material of iron-rich sludge-straw-based mixed biomass char loaded with calcium peroxide; the composite material of iron-rich sludge-straw-based mixed biomass char loaded with calcium peroxide is prepared by coupling iron-rich sludge carbon, straw biomass carbon and calcium peroxide under the action of an adhesive.

[0008] More preferably, the preparation method of the composite material for recovering nitrogen and phosphorus in water and simultaneously removing antibiotics includes the following steps:

[0009] Step 1: After the collected iron-rich sludge is naturally air-dried, it is dried in an oven at 60-80°C to obtain dehydrated iron-rich sludge; then the dehydrated iron-rich sludge is placed in a muffle furnace for high-temperature carbonization treatment. After it cools in the furnace, it is crushed to obtain iron-rich sludge carbon.

[0010] Step 2: After the straw is washed, cut into pieces, and dried, it is placed in a tubular furnace for high-temperature carbonization treatment. After it cools in the furnace, straw biomass carbon is obtained.

[0011] Step 3: Iron-rich sludge carbon, straw biomass carbon, and calcium peroxide are coupled in a certain proportion under the action of a binder, and then centrifuged, washed, and dried to obtain a composite material.

[0012] Preferably, in Step 1, the carbonization treatment process is as follows: At room temperature, the dehydrated iron-rich sludge is placed in a muffle furnace, the temperature is set at 400-800°C, and it is heated to the specified temperature at a heating rate of 8-12°C / min, and then calcined for 3-6 hours.

[0013] Preferably, in Step 2, the carbonization treatment process is as follows: The treated straw is placed in a tubular furnace, the temperature is set at 600-800°C, and under nitrogen protection, it is heated to the specified temperature at a heating rate of 4-7°C / min, and then calcined for 1-3 hours.

[0014] Preferably, in Step 3, the specific preparation method of the composite material is as follows:

[0015] (1) Iron-rich sludge carbon and straw biomass carbon are added to a ball mill in a certain proportion, and ball milled at a speed of 900-1200 rpm for 2-3 times, each time lasting for 1-3 minutes, with an interval of 30-60 seconds between every two times, to obtain iron-rich sludge-straw mixed biomass carbon.

[0016] (2) Under magnetic stirring, calcium peroxide is slowly added to the binder. After the addition is complete, continuous stirring is carried out, and iron-rich sludge-straw mixed biomass carbon is added to the mixed solution. After continuous stirring for 2-4 hours, a mixture is obtained.

[0017] (3) A small amount of distilled water is added to the mixture, and it is transferred to a centrifuge tube and centrifuged at a speed of 3000-5000 rpm for 10-20 minutes. After filtration, it is dried at 60-80°C and then naturally cooled to room temperature to obtain a composite material.

[0018] Preferably, the mass ratio of the iron-rich sludge carbon to the straw biomass carbon is (2-5):1.

[0019] Preferably, when the addition amount of the binder is 30 mL, the mass ratio of the calcium peroxide to the iron-rich sludge-straw mixed biomass carbon is 1:(1.5-7.5).

[0020] Preferably, the binder is polyethylene glycol; the polyethylene glycol includes but is not limited to PEG200.

[0021] Preferably, after the composite material is applied to actual water bodies, after recovering nitrogen and phosphorus in the water body and removing antibiotics at the same time, and through separation, nitrogen phosphorus / composite material can be recovered, which can be reused for improving the fertility of barren soil and used as a modifier for barren soil.

[0022] Preferably, the nitrogen phosphorus / composite material is the composite material prepared by adsorbing and removing nitrogen, phosphorus and antibiotics in sewage, and finally the recovered composite material loaded with nitrogen and phosphorus.

[0023] The beneficial effects of the present invention are as follows:

[0024] (1) The iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material for recovering nitrogen and phosphorus in water bodies and removing antibiotics at the same time prepared by the present invention is selected from the aerobic-section effluent sludge of a coking wastewater treatment plant and agricultural waste straw, and has the green environmental protection concept of "sludge resource utilization" and "agricultural waste resource utilization";

[0025] (2) The preparation method of the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material for recovering nitrogen and phosphorus in water bodies and removing antibiotics at the same time provided by the present invention has a simple process, convenient operation, easily available raw materials, and is easy to scale up production;

[0026] (3) When the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material prepared by the present invention is added to water, calcium peroxide can be quickly released, and nitrogen can be efficiently enriched through chemical action; at the same time, the composite material itself has more pores and a larger specific surface area. On the one hand, it has a large adsorption effect and can quickly adsorb nitrogen-containing substances and antibiotics. On the other hand, under the action of the hydrolysis of calcium peroxide and iron-containing compounds, an iron-carbon microelectrolysis reaction occurs, which can efficiently degrade and remove the water body and the adsorbed antibiotics. In addition, calcium hydroxide and iron-containing minerals formed in the water body can further enrich the nitrogen and phosphorus substances in the water body, further improving the efficiency of nitrogen and phosphorus adsorption and antibiotic removal;

[0027] (4) After the composite material provided by the present invention adsorbs and enriches nitrogen and phosphorus nutrients in the water body, it is then applied to improve the fertility of barren soil, such as the restoration of mine soil and the afforestation of barren mountains, so as to truly achieve the purpose of waste resource utilization. Description of the Drawings

[0028] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation to the present invention. In the drawings:

[0029] Figure 1 It is the SEM image of the calcium peroxide - loaded composite of iron - rich sludge - straw - based mixed biochar prepared before the examples;

[0030] Figure 2 It is the XPS image of the calcium peroxide - loaded composite of iron - rich sludge - straw - based mixed biochar prepared before the examples for characterizing nitrogen elements;

[0031] Figure 3 It is the XPS image of the calcium peroxide - loaded composite of iron - rich sludge - straw - based mixed biochar prepared before the examples for characterizing phosphorus elements;

[0032] Figure 4 It is the intuitive graph of the removal rates of the simulated wastewater containing ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin with different initial concentrations treated by the calcium peroxide - loaded composite of iron - rich sludge - straw - based mixed biochar in Examples 1 - 6; from left to right on the graph correspond to Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6 respectively;

[0033] Figure 5 It is the XPS graph of the nitrogen - phosphorus - loaded composite recovered after the removal effect in Example 7 for characterizing nitrogen elements;

[0034] Figure 6 It is the XPS graph of the nitrogen - phosphorus - loaded composite recovered after the removal effect in Example 7 for characterizing phosphorus elements. Detailed implementation manners

[0035] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0036] Experimental scheme: Step 1: Preparation of iron - rich sludge biochar: (1) Take the aerobic - section effluent iron - rich sludge from the coking wastewater treatment plant, first air - dry it at room temperature for a period of time, then put it into an oven and bake it at 75 °C for 24 h. After it naturally cools to room temperature, dehydrated iron - rich sludge is obtained; (2) At room temperature, put the dehydrated iron - rich sludge into a crucible and place it in a muffle furnace for high - temperature carbonization treatment. Set the temperature at 600 °C and increase the temperature at a rate of 10 °C / min until the specified temperature is reached, and then continue to calcine for 4 h to make it fully pyrolyzed and carbonized. After calcination, wait for it to naturally cool to room temperature and take it out and crush it to obtain iron - rich sludge biochar.

[0037] Step 2: Preparation of straw biochar: Using agricultural waste straw as raw material, after simple cleaning, cutting it into pieces and drying, place it in a tube furnace, set the temperature at 700 °C, and increase the temperature at a rate of 5 °C / min until the specified temperature is reached, then continue to calcine for 2 h to fully pyrolyze and carbonize it. After calcination, wait for it to cool naturally to room temperature to obtain straw biochar.

[0038] Step 3: Preparation of the composite material: (1) Add iron-rich sludge biochar and straw biochar into a ball mill at a mass ratio of 2:1, ball mill at a speed of 1100 rpm for 3 times, each time lasting for 2 min, with an interval of 40 s between every two times, to obtain iron-rich sludge-straw mixed biochar; (2) Under magnetic stirring, slowly add 25 g of calcium peroxide to 300 mL of PEG200. After adding, continue stirring, and add 75 g of iron-rich sludge-straw mixed biochar to the mixed solution. After continuously stirring for 2 h, obtain a mixture; (3) Add a small amount of distilled water to the mixture, transfer it to a centrifuge tube, centrifuge at a speed of 4000 rpm for 15 min, filter, dry at 80 °C, and wait for it to cool naturally to room temperature to obtain an iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material.

[0039] Examples 1-7: Explore the removal rates of ammonia nitrogen, phosphate, and antibiotics of the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material prepared according to the test plan:

[0040] Examples 1-6: Explore the removal rates of the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material in simulated wastewater with different concentrations of ammonia nitrogen, phosphate, and antibiotics; the specific data of the removal rates of ammonia nitrogen, phosphate, and antibiotics in Examples 1-6 are shown in Table 1, and the intuitive graph is as Figure 4 shown (from left to right on the graph correspond to Example 1, Example 2, Example 3, Example 4, Example 5, and Example 6 respectively);

[0041] Example 1: Under normal temperature and pressure conditions, use NH4Cl, KH2PO4, and norfloxacin to simulate wastewater. Prepare 200 mL of simulated wastewater with a concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin of 60:140:40. Add 0.3 g of the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material to the simulated wastewater, conduct continuous magnetic stirring. After reacting for 24 h, take 2 mL of the sample, filter it through a 0.45 μm membrane, and use a Nessler reagent spectrophotometer, anion chromatography, and high-performance liquid chromatography to detect the contents of ammonia nitrogen, phosphate, and antibiotics, and calculate the removal rates of each pollutant;

[0042] Example 2: Referring to Example 1, the changed content is: Prepare 200 mL of simulated wastewater with the concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin being 80:150:50; other conditions are the same as in Example 1.

[0043] Example 3: Referring to Example 1, the changed content is: Prepare 200 mL of simulated wastewater with the concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin being 100:160:60; other conditions are the same as in Example 1.

[0044] Example 4: Referring to Example 1, the changed content is: Prepare 200 mL of simulated wastewater with the concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin being 120:170:70; other conditions are the same as in Example 1.

[0045] Example 5: Referring to Example 1, the changed content is: Prepare 200 mL of simulated wastewater with the concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin being 140:180:80; other conditions are the same as in Example 1.

[0046] Example 6: Referring to Example 1, the changed content is: Prepare 200 mL of simulated wastewater with the concentration ratio of ammonia nitrogen (calculated as N), phosphate (calculated as P), and norfloxacin being 160:190:90; other conditions are the same as in Example 1.

[0047] Table 1

[0048] Example Ammonia nitrogen removal rate (%) Phosphate removal rate (%) Norfloxacin removal rate (%) Example 1 58.6 90.8 76.2 Example 2 41.3 88.9 68.5 Example 3 33.2 88.2 67.2 Example 4 33.8 87.4 66.6 Example 5 26.6 82.1 56.8 Example 6 20.8 78.8 52.2

[0049] According to the data in Table 1, it can be seen that by adding a small amount of the material of the present invention to the high-concentration simulated wastewater in the laboratory, the removal effects of ammonia nitrogen, phosphate, and norfloxacin in the wastewater are all very good. Among them, the removal rate of phosphate is the highest, up to 90.8%, followed by norfloxacin and ammonia nitrogen; it shows that the material of the present invention can efficiently remove the mixed pollution of high-concentration ammonia nitrogen, phosphate, and norfloxacin in water bodies simultaneously.

[0050] Example 7: Based on the experimental results of Examples 1 - 6, apply the prepared iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material to the actual black and odorous water body:

[0051] Under normal temperature and pressure, take 200 mL of the eluate of the actual black and odorous river bottom mud and add it to a beaker. After detecting the contents of ammonia nitrogen, phosphate, and antibiotics in the water body, add 0.3 g of the iron-rich sludge-straw-based mixed biochar loaded with calcium peroxide composite material to the beaker. After reacting for 8 h and 24 h, take 2 mL of the sample respectively, filter it through a 0.45 μm membrane, and detect the contents of ammonia nitrogen, phosphate, and antibiotics by using a Nessler reagent spectrophotometer, anion chromatography, and high-performance liquid chromatography respectively. The specific data are shown in Table 2:

[0052] Table 2

[0053]

[0054] As can be seen from the data in Table 2, the calcium peroxide composite loaded with iron-rich sludge-straw-based hybrid biochar prepared by the present invention has remarkable effects on the removal of ammonia nitrogen, phosphate and antibiotics in actual black and odorous water bodies. In only 8 hours, the removal rate of ammonia nitrogen reaches 70.7%, and phosphate and antibiotics in the water body are basically undetectable; after 24 hours, the removal rate of ammonia nitrogen increases to 94.4%.

[0055] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or further includes elements inherent to such process, method, article or device.

[0056] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. Preparation method of composite material for simultaneously removing nitrogen, phosphorus and antibiotics in water body, characterized in that: It is prepared by coupling ferric-rich sludge carbon, straw biochar and calcium peroxide under the action of a binder.

2. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics from water body according to claim 1, wherein: It includes the following steps: Step 1: Dry the ferric-rich sludge to obtain dehydrated ferric-rich sludge; Then place the dehydrated ferric-rich sludge in a muffle furnace for high-temperature carbonization treatment, and finally crush it to obtain ferric-rich sludge carbon; Step 2: After cleaning, cutting and drying the straw, place it in a tube furnace for high-temperature carbonization treatment to obtain straw biochar; Step 3: Mix ferric-rich sludge carbon, straw biochar, calcium peroxide and a binder, and after coupling, centrifuging, washing and drying, a composite material is obtained.

3. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics in the recovered water body according to claim 2, wherein: In the said Step 1, the carbonization treatment process is as follows: At room temperature, place the dehydrated ferric-rich sludge in a muffle furnace, set the temperature at 400 - 800 °C, heat it to the specified temperature at a heating rate of 8 - 12 °C / min, and then continue to calcine for 3 - 6 h.

4. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics in water body according to claim 2, characterized in that: In the said Step 2, the carbonization treatment process is as follows: Place the treated straw in a tube furnace, set the temperature at 600 - 800 °C, under nitrogen protection, heat it to the specified temperature at a heating rate of 4 - 7 °C / min, and then continue to calcine for 1 - 3 h.

5. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics in recycled water according to claim 2, characterized in that: In the said Step 3, the specific preparation method of the composite material is as follows: (1) Add ferric-rich sludge carbon and straw biochar into a ball mill, ball mill at a speed of 900 - 1200 rpm for 2 - 3 times, each time lasting for 1 - 3 min, with an interval of 30 - 60 s between every two times, to obtain ferric-rich sludge-straw mixed biochar; (2) Under the action of magnetic stirring, slowly add calcium peroxide into the binder, continuously stir, and add ferric-rich sludge-straw mixed biochar into the mixed solution. After continuously stirring for 2 - 4 h, a mixture is obtained; (3) Add distilled water into the mixture and transfer it to a centrifuge tube. Centrifuge at a speed of 3000 - 5000 rpm for 10 - 20 min, filter, dry at 60 - 80 °C, and wait for it to cool naturally to room temperature to obtain the composite material.

6. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics from water body according to claim 5, characterized in that: The mass ratio of the ferric-rich sludge carbon to the straw biochar is (2 - 5):1; the binder is polyethylene glycol.

7. The preparation method of the composite material for simultaneously removing nitrogen, phosphorus and antibiotics from water body according to claim 5, characterized in that: When the addition amount of the binder is 30 mL, the mass ratio of the calcium peroxide to the ferric-rich sludge-straw mixed biochar is 1:(1.5 - 7.5).

8. A composite material prepared by the preparation method of the composite material for simultaneously removing antibiotics while recovering nitrogen and phosphorus in water according to any one of claims 1 - 7.

9. Application of a composite material for simultaneously removing nitrogen, phosphorus and antibiotics in water bodies, characterized in that: After the composite material described in claim 8 is used for recovering nitrogen and phosphorus while removing antibiotics in water, nitrogen and phosphorus / composite material is recovered.

10. Application of a composite material for simultaneously removing nitrogen, phosphorus and antibiotics from water bodies, characterized in that: The nitrogen and phosphorus / composite material described in claim 9 is used as a modifier for barren soil.

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