A porous material coupled with magnesium powder as a filler, its preparation method and application

Abstract

The present application relates to sewage treatment technical field, provide a kind of porous material coupling magnesium powder's filler and its preparation method and application.The porous material coupling magnesium powder's filler includes 40 ~ 60 mass parts of magnesium, 20 ~ 35 mass parts of porous material, 5 ~ 20 mass parts of inorganic carbon source and 5 ~ 10 mass parts of binder.The porous material coupling magnesium powder's filler provided by the present application can be used for the treatment of low carbon-nitrogen ratio sewage, has good nitrate treatment effect, and solves the problems of high cost of filler, easy to channel flow or mineralization.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically, to a porous material coupled with magnesium powder as a filler, its preparation method, and its application. Background Technology

[0002] Nitrate pollution is one of the most critical water quality issues today. Excessive nitrate levels in drinking water are detrimental to human health, potentially causing cancer and other illnesses. Furthermore, excessive nitrates in water can lead to numerous ecological problems, such as eutrophication of water sources, excessive N2O emissions, and habitat degradation. Heterotrophic denitrification is the mainstream method for removing nitrates from water. This method requires sufficient organic carbon sources in the water, but most wastewater has a low carbon-to-nitrogen ratio, necessitating the addition of organic carbon sources such as methanol, ethanol, and sodium acetate, which is costly and may cause secondary pollution. Moreover, heterotrophic denitrification produces a large amount of sludge, further increasing costs through treatment.

[0003] In contrast, autotrophic denitrification avoids the use of organic carbon sources, thus reducing costs and secondary pollution, making it ideal for removing nitrates from water with a low C / N ratio. Current electron donors mainly include hydrogen, sulfur, iron, and related compounds such as ferrisulfides and thiosulfates. However, hydrogen is expensive and difficult to store and transport; sulfur and sulfides produce large amounts of sulfate and can cause pipe blockages and channeling problems; iron and its ferrisulfides have low denitrification efficiency and serious mineralization issues.

[0004] Therefore, it is of great significance to develop a new type of autotrophic denitrification electron donor as a wastewater treatment packing material to reduce transportation and storage costs, reduce or avoid sludge formation and mineralization, and have a more efficient denitrification process. Summary of the Invention

[0005] The purpose of this invention is to provide a porous material coupled with magnesium powder as a filler and its preparation method, so as to solve the technical problems of high cost, easy channeling or mineralization, and unsatisfactory nitrate nitrogen treatment effect of fillers used in nitrate wastewater treatment in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, the present invention provides a porous material coupled with magnesium powder as a filler, comprising the following components in parts by mass:

[0008] Magnesium: 40-60 parts;

[0009] Porous materials: 20-35 parts;

[0010] Inorganic carbon source: 5-20 parts;

[0011] Adhesive: 5-10 parts.

[0012] The magnesium in the porous material coupled with magnesium powder provided by this invention exists in the form of elemental magnesium. When combined with the porous material, it allows autotrophic denitrifying bacteria to grow in large quantities on the surface of the porous material and form a biofilm. Through the autotrophic denitrification process using magnesium and hydrogen as electron donors, nitrates in the water are synergistically treated.

[0013] The porous material coupled with magnesium powder provided by this invention is applied to wastewater treatment. Autotrophic denitrifying bacteria utilize the magnesium in the packing material and the hydrogen gas generated from magnesium in the water as electron donors to convert nitrate nitrogen in the wastewater into nitrogen gas. The specific reaction process is as follows:

[0014] 5Mg + 2NO3 - +6H₂O→5Mg 2+ +N2+12OH -

[0015] Mg + H₂O → H₂ + Mg(OH)₂

[0016] 5H2+2NO3 - →N2+2OH - +4H2O.

[0017] According to some embodiments of the present invention, the filler particle size is 8~12mm.

[0018] According to some embodiments of the present invention, the porous material includes at least one of porous biomaterials, porous organic materials, and porous inorganic materials.

[0019] According to some embodiments of the present invention, the porous biomaterial includes porous natural biomaterials containing cellulose.

[0020] According to some embodiments of the present invention, the porous biomaterial includes at least one of sawdust, corn cob, and grapefruit peel.

[0021] According to some embodiments of the present invention, the porous organic material includes at least one of polyurethane foam, organic multifaceted hollow spheres, and organic Pall rings.

[0022] According to some embodiments of the present invention, the porous inorganic material includes at least one of molecular sieves, zeolites, activated carbon, pumice, rock wool, porous ceramics, and perlite.

[0023] According to some embodiments of the present invention, the inorganic carbon source includes at least one of calcium carbonate, sodium carbonate, sodium bicarbonate, magnesium carbonate, zinc carbonate, and ferrous carbonate.

[0024] According to some embodiments of the present invention, the inorganic carbon source includes calcium carbonate, sodium carbonate, and sodium bicarbonate.

[0025] According to some embodiments of the present invention, the mass ratio of calcium carbonate, sodium carbonate and sodium bicarbonate is (2~4):(2~3):(3~4).

[0026] According to some embodiments of the present invention, the adhesive comprises the following components in weight percentage: 25-33% ammonium sulfate, 13-15% silica fume, 7-10% sorbitol, 12-15% nitrile rubber, 12-15% butyl acrylate and 20-24% gypsum dihydrate.

[0027] According to some embodiments of the present invention, the preparation method of the adhesive includes: feeding butyl acrylate and nitrile rubber into a mixer for internal mixing; adding the above-mixed raw materials, ammonium sulfate, silica fume, sorbitol and gypsum dihydrate into a grinding mill and grinding to obtain the adhesive.

[0028] In a second aspect, the present invention provides a method for preparing the filler described in the first aspect, comprising: mixing magnesium powder, porous material, inorganic carbon source, binder and water, stirring, granulating, and vacuum drying to obtain the filler.

[0029] The porous material coupled with magnesium powder filler provided by the present invention is prepared by solution bonding and drying method from raw materials including magnesium powder, porous material, inorganic carbon source and binder.

[0030] According to some embodiments of the present invention, the particle size of the magnesium powder is 20~500μm.

[0031] According to some embodiments of the present invention, the particle size of the inorganic carbon source is 50~500μm.

[0032] According to some embodiments of the present invention, the stirring time is 1 to 2 hours.

[0033] According to some embodiments of the present invention, the vacuum drying time is 5 to 7 hours.

[0034] According to some embodiments of the present invention, the filler particle size is 8~12mm.

[0035] Thirdly, the present invention provides an autotrophic denitrification reactor, comprising the packing material described in the first aspect or the packing material prepared by the preparation method described in the second aspect.

[0036] According to some embodiments of the present invention, the packing material occupies 60% to 80% of the reactor volume.

[0037] Fourthly, the present invention provides the application of the packing material described in the first aspect, the packing material prepared by the preparation method described in the second aspect, and the reactor described in the third aspect in wastewater treatment; particularly in the treatment of wastewater with dissolved oxygen concentration below 3.0 mg / L and COD concentration to nitrate nitrogen concentration ratio (C / N) less than 3.

[0038] The beneficial effects of this invention are at least as follows:

[0039] (1) The porous material coupled with magnesium powder provided by the present invention is mainly made of magnesium powder, porous materials, inorganic carbon source, etc., and its production, transportation and storage costs are much lower than those of hydrogen autotrophic denitrification packing.

[0040] (2) The magnesium contained in the porous material coupled with magnesium powder and the small amount of hydrogen generated by magnesium in water together serve as electron donors for autotrophic denitrification. The system has more types of autotrophic denitrifying bacteria and the bacterial community is more stable, thus making the denitrification effect of the packing material in treating nitrate-containing wastewater more stable.

[0041] (3) The porous material coupled with magnesium powder provided by the present invention does not have the problem of filler mudding, and will not cause channeling, blockage of pipelines, etc.

[0042] (4) Since magnesium has a stronger reducing power than iron, the porous material coupled with magnesium powder provided by the present invention has a higher efficiency in treating nitrate-containing wastewater than iron autotrophic denitrification.

[0043] (5) The pH range of magnesium ion precipitation is 9.4 to 12.4. The porous material coupled with magnesium powder filler provided by the present invention can avoid mineralization problems caused by iron ion precipitation.

[0044] (6) The porous material coupled with magnesium powder provided by the present invention utilizes porous material, which increases the biofilm position of microorganisms, making it more conducive to microorganism attachment, and has physical adsorption properties, which is more conducive to microorganisms utilizing nitrates, thereby increasing the ability of a unit volume of packing to treat nitrates. Attached Figure Description

[0045] Figure 1 A schematic diagram of the reactor used to evaluate the wastewater treatment effect of the packing material. Detailed Implementation

[0046] To make the technical problem to be solved, the technical solution, and the beneficial effects of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely for illustrating this patent and do not limit the scope of protection of this invention in any way.

[0047] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the reagents used in the following embodiments are conventional biochemical reagents; the raw materials, instruments, and equipment used in the following embodiments can all be obtained commercially or by existing methods; unless otherwise specified, the reagent dosages are those used in routine experimental operations; unless otherwise specified, the experimental methods are conventional methods.

[0048] The materials used in the various embodiments and comparative examples of the present invention are as follows:

[0049] Magnesium powder: Particle size 50~200μm.

[0050] Calcium carbonate, sodium carbonate, sodium bicarbonate: particle size 50~200μm.

[0051] Iron powder: particle size 50~200μm.

[0052] Wood chips: particle size 1~2mm.

[0053] Corn cob powder: Dry the corn cobs and crush them into powder of 1~2mm.

[0054] Polyurethane foam material: prepared by polyurethane formate, with a pore density of 25 ppi and a density of 0.20~0.23 g / cm³. 3 The particle size is 20~60mm.

[0055] Multifaceted hollow sphere: Made of polypropylene, with a specification of DN25.

[0056] Molecular sieves: particle size 50~100μm.

[0057] Zeolite: Natural zeolite, with a particle size of 50~100μm and a specific surface area of ​​300~500m². 2 / g, with a packing density of 1.5~2.3cm³. 3 / g.

[0058] Pumice: Natural pumice, with a particle size of 50~100μm and a specific surface area of ​​100~160m². 2 / g, with a packing density of 2.4~3.6cm³. 3 / g.

[0059] Preparation Example 1

[0060] 12 parts by weight of butyl acrylate and 12 parts by weight of nitrile rubber (powdered nitrile rubber P83) are put into a mixer and mixed thoroughly. The mixed raw materials are then added to a grinder, along with 30 parts by weight of ammonium sulfate, 15 parts by weight of silica fume, 10 parts by weight of sorbitol and 21 parts by weight of gypsum dihydrate. The mixture is then ground to 25 μm to obtain adhesive A.

[0061] Preparation Example 2

[0062] Add 15 parts by weight of butyl acrylate and 15 parts by weight of nitrile rubber (powdered nitrile rubber P83) to a mixer and mix them thoroughly. Add the mixed raw materials to a grinder and add 25 parts by weight of ammonium sulfate, 14 parts by weight of silica fume, 7 parts by weight of sorbitol and 24 parts by weight of gypsum dihydrate to the grinder. Grind to 25 μm to obtain adhesive B.

[0063] Preparation Example 3

[0064] 15 parts by weight of butyl acrylate and 12 parts by weight of nitrile rubber (powdered nitrile rubber P83) are put into a mixer and mixed thoroughly. The mixed raw materials are then added to a grinder, along with 33 parts by weight of ammonium sulfate, 13 parts by weight of silica fume, 7 parts by weight of sorbitol and 20 parts by weight of gypsum dihydrate. The mixture is then ground to 25 μm to obtain adhesive C.

[0065] Example 1

[0066] Magnesium powder, inorganic carbon source, binder A, and sawdust were mixed in a mass ratio of 50:20:10:20 with an appropriate amount of water (the volume ratio of water to other components was approximately 1:2). The mixture was stirred for 1 hour, mechanically granulated, and vacuum dried for 6 hours to obtain filler #1. The particle size of filler #1 was 8~12 mm.

[0067] The inorganic carbon source is calcium carbonate, sodium carbonate, and sodium bicarbonate in a mass ratio of 2:1:2.

[0068] Example 2

[0069] Magnesium powder, inorganic carbon source, binder B, and sawdust were mixed in a mass ratio of 55:15:5:25 with an appropriate amount of water (the volume ratio of water to other components was approximately 1:2). The mixture was stirred for 1 hour, mechanically granulated, and vacuum dried for 6 hours to obtain filler #2. The particle size of filler #2 was 8~12 mm.

[0070] The inorganic carbon source is calcium carbonate, sodium carbonate, and sodium bicarbonate in a mass ratio of 1:1:2.

[0071] Example 3

[0072] Magnesium powder, inorganic carbon source, binder C, and sawdust were mixed in a mass ratio of 50:10:10:30 with an appropriate amount of water (the volume ratio of water to other components was approximately 1:2). The mixture was stirred for 1 hour, mechanically granulated, and vacuum dried for 6 hours to obtain filler #3. The particle size of filler #3 was 8~12 mm.

[0073] The inorganic carbon source is calcium carbonate, sodium carbonate, and sodium bicarbonate in a mass ratio of 2:1:2.

[0074] Example 4

[0075] The preparation method of the filler is the same as in Example 1, except that the "wood chips" are replaced with "corn cob powder" to obtain filler #4.

[0076] Example 5

[0077] The filler was prepared according to Example 1, except that "wood chips" were replaced with "polyurethane foam" to obtain filler #5.

[0078] Example 6

[0079] The preparation method of the filler is the same as in Example 1, except that the "wood chips" are replaced with "multi-surface hollow spheres" to obtain filler #6.

[0080] Example 7

[0081] The preparation method of the filler is the same as in Example 1, except that the "wood chips" are replaced with "molecular sieves" to obtain filler #7.

[0082] Example 8

[0083] The preparation method of the filler is the same as in Example 1, except that the "wood chips" are replaced with "zeolite" to obtain filler #8.

[0084] Example 9

[0085] The preparation method of the filler is the same as in Example 1, except that the "wood chips" are replaced with "pumice" to obtain filler #9.

[0086] Comparative Example 1

[0087] The packing material was prepared according to Example 1, except that no inorganic carbon source was added, and packing material D1 was obtained.

[0088] Comparative Example 2

[0089] The preparation method of the filler is the same as in Example 1, except that no sawdust is added, and filler D2 is obtained.

[0090] Comparative Example 3

[0091] The preparation method of the filler is the same as in Example 1, except that the magnesium powder is replaced with iron powder to obtain filler D3.

[0092] Wastewater treatment effect evaluation

[0093] The fillers prepared in each embodiment and comparative example were added. Figure 1 The reactor shown was used to conduct an evaluation test on the effectiveness of wastewater treatment.

[0094] Figure 1 The reactor shown is a packed column reactor, including a reactor body 1 and a three-phase separator 2 set on the top of the reactor body 1. The reactor body 1 is a sealed plexiglass container with an inner diameter of 10 cm and a volume of 5 L. The three-phase separator 2 is used to separate mud and water vapor. The bottom of the reactor body 1 is provided with an inlet 3 and the top of the reactor is provided with an outlet 4. The side wall of the reactor body 1 is provided with a reflux inlet 6, a sampling port 5 and a reflux outlet 7 from bottom to top.

[0095] The packing materials prepared in each embodiment and comparative example were loaded into reactor body 1. Simulated nitrogen-containing wastewater without organic carbon sources was prepared, and dissolved oxygen was controlled below 3 mg / L using nitrogen oxygenation. Sludge acclimated in the laboratory for one year was inoculated onto the packing material and subjected to secondary acclimation using the simulated wastewater. The wastewater was then pumped into the reactor using a peristaltic pump. The influent nitrate nitrogen concentration is shown in Table 1. The reactor was operated in continuous flow mode without deoxygenation facilities or processes, with the temperature controlled at 20-25℃, a reflux ratio of 5, and the system pH stability range shown in Table 1. Dissolved oxygen was below 0.3 mg / L. The reactor was operated continuously for two months at a hydraulic retention time (HRT) of 4 h. During this period, the effluent nitrate nitrogen concentration was measured, and the effluent nitrate nitrogen removal rate was calculated. The results are shown in Table 1.

[0096] The nitrate nitrogen concentration was tested using ion chromatography (HJ / T84-2001); the nitrate nitrogen removal rate in Table 1 is the average value.

[0097] The autotrophic denitrifying bacteria used in the above wastewater treatment effect evaluation process were taken from sludge that had been domesticated and screened for one year in the laboratory.

[0098] Table 1

[0099]

[0100] The reactors loaded with the packing materials prepared in Examples 1-9 ran continuously for 2 months, and the effluent quality was stable, indicating that the autotrophic denitrification process of the porous material coupled with magnesium powder packing material provided by the present invention as an electron donor can efficiently remove nitrate nitrogen from wastewater.

[0101] The packing material prepared in Comparative Example 1 did not contain an inorganic carbon source, resulting in a lack of inorganic carbon source in the reactor. Moreover, inorganic carbon source can also act as a pH regulator. The lack of inorganic carbon source will cause the pH to drop during the autotrophic denitrification process, deviating from the optimal pH range, thus leading to a significant decrease in denitrification efficiency.

[0102] The packing material prepared in Comparative Example 2 did not contain porous materials, making it difficult for microorganisms to attach and grow, resulting in a significant decrease in denitrification efficiency.

[0103] In Comparative Example 3, the magnesium metal component was replaced with iron in the packing material. The denitrification efficiency was better in the early stage of the device operation, which was slightly worse than that in Example 1, but the difference was not obvious. However, during the operation, the surface of the packing material gradually turned iron red, and the denitrification efficiency continued to decline. It is speculated that ferric iron deposits accumulated on the surface of the packing material during the reaction process and affected the subsequent utilization of the packing material.

[0104] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A denitrification packing of autotrophic type with porous material coupled with magnesium powder, characterized in that, The filler comprises the following components by mass fraction: Magnesium: 40-60 parts; Porous material: 20-35 parts; Inorganic carbon source: 5-20 parts; Binder: 5-10 parts; The porous material comprises a natural biological material with a porous structure containing cellulose; and / or, the porous material comprises at least one of polyurethane foam, organic material multi-faceted hollow sphere, and organic material Pall ring; and / or, the porous material comprises at least one of molecular sieve, zeolite, activated carbon, pumice, rock wool, porous ceramic, and perlite; The inorganic carbon source comprises at least one of calcium carbonate, sodium carbonate, sodium bicarbonate, magnesium carbonate, zinc carbonate, and ferrous carbonate.

2. The filler of claim 1, wherein The porous material comprises at least one of wood chips, corn cobs, and pomelo peels.

3. The filler according to claim 1 or 2, characterized in that The binder comprises the following components by mass percentage: ammonium sulfate 25-33%, silica ash 13-15%, sorbitol 7-10%, nitrile rubber 12-15%, butyl acrylate 12-15%, and dihydrate gypsum 20-24%.

4. The filler of claim 3, wherein The preparation method of the binder comprises: feeding butyl acrylate and nitrile rubber into a banbury mixer for mixing; and feeding the above-mentioned mixed raw materials, ammonium sulfate, silica ash, sorbitol, and dihydrate gypsum into a grinder for grinding to obtain the binder.

5. The method of preparing the filler according to any one of claims 1 to 4, characterized in that, The filler comprises: The magnesium powder, porous material, inorganic carbon source, binder, and water are mixed, stirred, granulated, and vacuum dried to obtain the filler.

6. The preparation method according to claim 5, characterized in that, The stirring time is 1-2 hours; The vacuum drying time is 5-7 hours; The particle size of the filler is 8-12 mm.

7. An autotrophic denitrification reactor characterized in that, The filler comprises the filler of any one of claims 1-4 or the filler prepared by the preparation method of claim 5 or 6.

8. The reactor of claim 7, wherein, The filler accounts for 60%-80% of the volume of the reactor.

9. The filler of any one of claims 1-4, the filler prepared by the preparation method of claim 5 or 6, or the reactor of any one of claims 7-8 for use in sewage treatment.

10. Use according to claim 9, characterized in that, The use is for treating sewage with a dissolved oxygen concentration lower than 3.0 mg / L and a ratio of COD concentration to nitrate nitrogen concentration less than 3.

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