A sulfur-based autotrophic denitrifying and phosphorus-removing biological carrier containing magnesium, and a preparation method and application thereof

Abstract

The present application relates to a kind of sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier and its preparation method and application, belong to water deep processing field.The sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier includes matrix material and active material distributed in the inside and / or at least part of surface of the matrix material;The matrix material includes elemental sulfur and sulfur compound;The active material includes basic magnesium-containing compound and / or mineral containing basic magnesium-containing compound.The sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier has the ability of easy-to-use sulfur form by denitrification process and automatic adjustment system pH value, realizes deep denitrification and nitrogen removal, and the dissolved magnesium ion is transported into cell by improving ammonia nitrogen efficiency and forms phosphate precipitate, and the carrier is endowed with the function of efficient removal of ammonia nitrogen and phosphate.The sulfur-based basic magnesium-containing functional material provided by the present application is applied to deep processing or ecological buffer zone and other scenes, and can realize the coordinated deep removal of nitrate nitrogen, ammonia nitrogen and phosphate, and has wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of water advanced treatment, in particular to a sulfur-based autotrophic denitrification and phosphorus removal biological carrier with simultaneous and efficient removal of nitrate nitrogen, ammonia nitrogen and phosphate, and a preparation method and application thereof. BACKGROUND

[0002] Nitrogen is one of the main causes of water eutrophication and has been widely concerned. At present, the nitrogen capacity of ecological water bodies in most regions has tended to be saturated, and is on the verge of eutrophication explosion. The nutrient content (nitrate nitrogen, ammonia nitrogen and phosphate) in the secondary treated effluent of sewage treatment plants is relatively low, but it is enough to cause natural water eutrophication, which has become increasingly evident in the water quality changes of some inland river basins and lakes in recent years. Due to the limited self-purification capacity of water bodies, the environmental capacity of such regions is becoming saturated, and gradually increasing the total nitrogen emission limit of the surrounding pollution units is a powerful measure to prevent further deterioration of water quality. Although sewage treatment plants are constantly upgraded, there is still a big gap between the effluent quality and the natural water body, especially for environmentally sensitive areas, which generally need advanced treatment or rely on ecological buffer zones to narrow the gap between the effluent quality of sewage treatment plants and the natural water quality.

[0003] Sulfur autotrophic denitrification technology is a denitrification technology that has attracted much attention at present, mainly due to the low cost of elemental sulfur and the outstanding advantages of acting as an electron donor and biological carrier. However, there is a key problem with this technology, which is that the acid produced by denitrification has a negative impact on microbial activity, and external alkalinity is often needed to adjust the microbial growth environment.

[0004] A autotrophic denitrification biological carrier (CN 208980406 U) is disclosed in the prior art, which is composed of sulfur and limestone (CaCO3), and the substrate is sulfur, and the surface and interior are integrated with limestone particles to adjust the system pH and supplement the carbon source. However, the nitrate nitrogen removal capacity of this carrier applied to the advanced treatment system is limited, and it also has no obvious removal effect on the residual ammonia nitrogen and phosphate in the secondary effluent.

[0005] A slow-release electron donor and a method for advanced denitrification of wastewater using the same (CN 109879415 B) and a denitrification and phosphorus removal active biological carrier, a preparation method thereof and an application thereof (CN 109019877 B) are also disclosed in the prior art. Sulfur and siderite are physically fused together to form an integrated composite biological carrier with a new structure without changing its composition. The sulfur in the new structure can participate in the denitrification process to achieve advanced denitrification, and the siderite can assist in automatic pH adjustment, and the generated ferrous ions can be used for phosphorus removal and denitrification process. However, it still cannot remove the residual ammonia nitrogen in the secondary effluent.

[0006] Therefore, there is no autotrophic denitrification and phosphorus removal biological carrier with high efficiency in removing nitrate nitrogen, ammonia nitrogen and phosphate at present, which is used for deep treatment or ecological buffer zone to meet the needs of downstream environmentally sensitive water areas as receiving water. SUMMARY

[0007] To solve the above-mentioned technical problems, the purpose of the present application is to provide a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier with high efficiency in removing nitrate nitrogen, ammonia nitrogen and phosphate, which is used for deep treatment or ecological buffer zone to protect downstream environmentally sensitive water areas.

[0008] The second purpose of the present application is to provide a preparation method of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0009] The third purpose of the present application is to provide a sewage treatment device based on the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0010] The fourth purpose of the present application is to provide a sewage treatment method based on the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0011] To achieve the above-mentioned purposes, the technical solution adopted by the present application is: a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, comprising a matrix material and an active material distributed in the interior and / or at least part of the surface of the matrix material.

[0012] The matrix material comprises elemental sulfur and sulfur-containing compounds.

[0013] The active material comprises an alkaline magnesium-containing compound and / or a mineral containing the alkaline magnesium-containing compound.

[0014] Preferably, the alkaline magnesium-containing compound comprises magnesium carbonate and / or magnesium hydroxide.

[0015] Preferably, the mineral containing the alkaline magnesium-containing compound comprises magnesite, dolomite, brucite or serpentine.

[0016] Preferably, the mass ratio of the matrix material to the active material is 50:1 to 1:8.

[0017] More preferably, the mass ratio of the matrix material to the active material is 10:1 to 1:4.

[0018] Preferably, the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is in the form of a group, a block, a spherical-like shape or an irregular shape, and the maximum dimension is 1.5 to 12 mm.

[0019] More preferably, the particle size of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is 2 to 6 mm.

[0020] A preparation method of a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, comprising the following steps:

[0021] 1) melting the matrix material into a liquid state at 120-180 DEG C;

[0022] 2) mixing the molten matrix material with the active material at 160-180 DEG C, maintaining a stirring speed of 400-700 rpm for 30-300 s, to obtain a uniform mixture;

[0023] 3) controlling the dropping speed to be 0.5-5 L·min -1 , and dropping the obtained mixture into cooling water at 4-60 DEG C drop by drop, and cooling and forming for 1-10 min;

[0024] 4) filtering, and placing the obtained solid substance in an oven, and drying at 40-60 DEG C for 12-48 h, to obtain the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0025] Preferably, before mixing the molten matrix material with the active material, the molten matrix material is subjected to impurity removal treatment.

[0026] More preferably, the impurity removal treatment specifically comprises: grading filtering the molten matrix material, and removing impurities greater than 0.8 mu m in the molten matrix material.

[0027] Preferably, before mixing the molten matrix material with the active material, the active material is subjected to crushing and screening treatment.

[0028] More preferably, the crushing and screening treatment specifically comprises: crushing the active material, screening through a 60-300 mesh screen, and taking undersize.

[0029] A wastewater treatment device based on a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, comprising: a packed bed or a fixed bed filter tank filled with a filler.

[0030] The filler comprises the above-mentioned sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0031] Preferably, the filler accounts for 10-90% of the volume of the fixed bed filter tank.

[0032] A wastewater treatment method based on a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, which utilizes the above-mentioned sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier to perform denitrification treatment and / or simultaneous ammonia nitrogen and phosphate removal on wastewater.

[0033] The present application has the following beneficial effects:

[0034] 1. The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the application has a sulfur form that is easy to be utilized by a denitrification process and the ability to automatically adjust the pH value of a system, realizes deep denitrification, and simultaneously has the functions of removing ammonia nitrogen and phosphate.

[0035] 2. The preparation method of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is simple, easy to operate, does not need to use relatively complex instruments or equipment, and does not depend on a special process.

[0036] 3. The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the application mainly comprises a matrix material and an active material, and the elemental sulfur in the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier prepared by the method in the application is converted from zero-valent sulfur into polysulfide and from ring-shaped sulfur into linear sulfur, which is more conducive to the enrichment of denitrification bacteria taking reduced sulfur as an electron donor, thereby strengthening the removal of nitrate.

[0037] 4. When a packed bed is constructed by using the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the application as a filler, the alkaline components such as OH - , CO3 2- , which are dissolved out during the denitrification process, can adjust the pH of the system, and the wastewater can be well treated.

[0038] 5. When a packed bed is constructed by using the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the application as a filler, the dissolved free magnesium ions can promote the absorption and utilization of ammonia nitrogen by nitrifying bacteria by improving the transport efficiency of ammonia nitrogen into cells. These two aspects simultaneously promote the efficient removal of ammonia nitrogen in the system.

[0039] 6. When a packed bed is constructed by using the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the application as a filler, the dissolved magnesium ions can combine with phosphate to form chemical precipitates, thereby realizing the control of phosphate in effluent.

[0040] 7. The device for treating wastewater provided by the application fills the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier as a filler in a packed bed or a fixed-bed filter tank, can realize the efficient removal of nitrate, ammonia nitrogen and phosphate, and can conveniently and quickly complete the filling when the carrier needs to be supplemented, and the material has good uniformity.

[0041] 8. The wastewater treatment method provided by the application can realize deep denitrification and has the effect of simultaneously and deeply removing ammonia nitrogen and phosphate. BRIEF DESCRIPTION OF DRAWINGS

[0042] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0043] Figure 1 A schematic diagram of the structure of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the present invention.

[0044] Figure 2 The surface scanning electron microscope (SEM) (a) and energy dispersive spectroscopy (EDS) (b) results of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the present invention.

[0045] Figure 3 The photoelectron spectroscopy (XPS) characterization results of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the present invention.

[0046] Figure 4 This is a schematic diagram of the wastewater treatment device provided by the present invention.

[0047] Figure label:

[0048] 1-Water inlet device, 2-Backwashing device, 3-Backwashing air passage and air inlet device, 4-Filter plate support, 5-Covering material, 6-Water outlet, 7-Fixed bed filter.

[0049] Figure 5 The SEM results of sediments collected after the wastewater treatment device provided by the present invention has been running for a period of time. Detailed Implementation

[0050] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, they are performed according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used where the manufacturer is not specified are all conventional products that can be purchased commercially.

[0051] The first aspect of this invention relates to a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, such as... Figure 1 As shown, it includes a matrix material and an active material distributed within the matrix material and / or at least partially on its surface.

[0052] The matrix material comprises elemental sulfur and sulfur-containing compounds.

[0053] The active material comprises alkaline magnesium-containing compounds and / or minerals containing alkaline magnesium-containing compounds.

[0054] Preferably, the alkaline magnesium-containing compounds comprise magnesium carbonate and / or magnesium hydroxide.

[0055] Preferably, the minerals containing alkaline magnesium-containing compounds comprise magnesite, dolomite, brucite or serpentine.

[0056] The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier has a sulfur form that is easily utilized by the denitrification process and the ability to automatically adjust the system pH, achieving deep denitrification, while also having the functions of removing ammonia nitrogen and phosphate.

[0057] During the denitrification process, the elemental sulfur on the surface of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is consumed, reducing nitrate nitrogen to nitrogen gas to achieve the goal of denitrification, while releasing hydrogen ions. The hydrogen ions can dissolve the carbonate / hydroxide and magnesium ions in the alkaline magnesium-containing compounds and / or minerals containing alkaline magnesium-containing compounds. The former can automatically adjust the system pH and also serve as a microbial carbon source, while the latter can accelerate the entry of ammonia nitrogen into the nitrifying bacteria process to enhance ammonia nitrogen removal, and can also combine with phosphate in the secondary effluent to form chemical precipitates to achieve phosphate removal.

[0058] Preferably, the mass ratio of the matrix material to the active material is 50:1 to 1:8.

[0059] More preferably, the mass ratio of the matrix material to the active material is 10:1 to 1:4 (e.g., 10:1, 4:1, 2:1, 1:1, or 1:4).

[0060] Further preferably, the mass ratio of the matrix material to the active material is more reasonable in terms of the amount of hydrogen ions, magnesium ions, and carbonate produced during the denitrification process, promoting the stable and persistent progress of the entire denitrification and phosphorus removal process.

[0061] Preferably, the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is in the form of a cluster, a block, a spherical-like shape, or an irregular shape, with a maximum dimension of 1.5 to 12 mm.

[0062] More preferably, the particle size of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is 2 to 6 mm (e.g., 2 mm, 3.5 mm, 4.5 mm, 5 mm, or 6 mm).

[0063] The second aspect of the present application also relates to a method for preparing a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, comprising the following steps:

[0064] 1) melt the matrix material into liquid state at 120-180℃ (e.g. 120℃, 130℃, 140℃, 160℃ or 180℃).

[0065] 2) mix the matrix material in molten state with the active material at 160-180℃ (e.g. 160℃, 165℃, 170℃, 175℃ or 180℃) with stirring at 400-700rpm (e.g. 400rpm, 500rpm, 600rpm or 700rpm) for 30-300s (e.g. 30s, 50s, 80s, 100s, 150s, 180s, 200s, 230s, 260s or 300s) to obtain a homogeneous mixture.

[0066] 3) control the dropping speed at 0.5-5L·min -1 (e.g. 0.5L·min -1 , 0.8L·min -1 , 1.5L·min -1 , 2.5L·min -1 , 4L·min -1 , 5L·min -1 ), and drop the mixture into cooling water at 4-60℃ (e.g. 4℃, 10℃, 20℃, 40℃, 50℃ or 60℃) drop by drop, and cool and shape for 1-10min (e.g. 1min, 2min, 5min, 6min, 8min or 10min).

[0067] 4) filter, and dry the obtained solid material in an oven at 40-60℃ (e.g. 40℃, 45℃, 50℃, 55℃ or 60℃) for 12-48h (e.g. 12h, 15h, 18h, 24h, 36h, 42h or 48h) to obtain the sulfur-based autotrophic denitrification and phosphorus removal bio-carrier.

[0068] Preferably, the matrix material in molten state is subjected to impurity removal treatment before being mixed with the active material.

[0069] More preferably, the impurity removal treatment specifically comprises: melting the matrix material in molten state at 120-180℃ (e.g. 120℃, 130℃, 140℃, 160℃ or 180℃) and standing, or grading the matrix material in molten state and removing impurities ≥0.8μm in the matrix material in molten state.

[0070] Removing impurities in the matrix material can further increase the content of effective components and improve the denitrification capacity of the autotrophic denitrification and phosphorus removal bio-carrier.

[0071] Preferably, the active material is pulverized and sieved before being mixed with the molten matrix material.

[0072] More preferably, the pulverization and sieving process specifically includes: pulverizing the active material, passing it through a 60-300 mesh sieve (e.g., 60 mesh, 80 mesh, 100 mesh, 120 mesh, 140 mesh, 150 mesh, 160 mesh, 190 mesh, 220 mesh, 250 mesh, 280 mesh, or 300 mesh), taking the undersize material, and using the sieved active material as raw material.

[0073] Selecting the particle size of the active material within a reasonable range can ensure a tighter connection between the active material and the matrix material, preventing stratification during the denitrification process.

[0074] A third aspect of the present invention also relates to a wastewater treatment device based on a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, comprising: a packed bed or fixed bed filter filled with packing material.

[0075] The packing material includes the aforementioned sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0076] The wastewater treatment device has excellent denitrification capabilities.

[0077] Preferably, such as Figure 4 As shown, the wastewater treatment device includes an inlet device 1, a backwashing device 2, a backwashing air passage and an air inlet device 3, a filter plate support 4, a packing material 5, an outlet 6, and a fixed bed filter tank 7.

[0078] Preferably, the bottom sidewall of the fixed bed filter is provided with an air inlet and a water inlet.

[0079] Preferably, the air inlet device is connected to the air inlet of the fixed bed filter through the backwashing air passage.

[0080] Preferably, the water inlet device is connected to the water inlet of the fixed bed filter.

[0081] Preferably, the backwash inlet at the bottom of the fixed bed filter is connected to the outlet of the backwashing device via a backwash water pipe.

[0082] Preferably, the supporting filter plate is placed inside the fixed bed filter tank.

[0083] Preferably, the supporting filter plate is positioned above the air inlet and water inlet located on the bottom side wall of the fixed bed filter tank.

[0084] Preferably, the packing material is placed on the supporting filter plate.

[0085] Preferably, the side wall at the top of the fixed bed filter is provided with a backwash outlet and a flushing outlet.

[0086] Preferably, the filler occupies 10-90% of the fixed bed filter volume.

[0087] The fourth aspect of the present application also relates to a wastewater treatment method based on the sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier, which uses the above-mentioned sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier to perform denitrification treatment on wastewater.

[0088] The present application will be further explained and described in conjunction with specific examples and comparative examples.

[0089] Example 1

[0090] The sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier provided in this example uses elemental sulfur and magnesium carbonate with a mass ratio of 10:1, and the preparation method comprises the following steps:

[0091] 1) The solid elemental sulfur is added to a heating kettle, and is heated to melt into liquid elemental sulfur at 140°C. The liquid elemental sulfur is subjected to fractional filtration to remove impurities with a particle size greater than 0.8 μm.

[0092] 2) The temperature of the heating kettle is increased and maintained at 160°C, and the undersize magnesium carbonate sieved through a 120-mesh sieve is added to the liquid elemental sulfur in the heating kettle. The temperature in the heating kettle is controlled at 160°C, and the mixture of magnesium carbonate and elemental sulfur is stirred and mixed at a frequency of 600 rpm for 50 s to obtain a uniform mixture.

[0093] 3) The dropping speed is maintained at 1.5 L·min -1 The above-mentioned mixture is dropped into 10°C cooling water drop by drop, and is cooled and formed for 1 min to form solid spherical particles.

[0094] 4) Filtration, the solid spherical particles are placed in an oven and dried at 40°C for 12 h to obtain a sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier with a particle size of 3-4 mm.

[0095] Example 2

[0096] The sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier provided in this example uses elemental sulfur and magnesite (the content of magnesium carbonate is about 90%) with a mass ratio of 10:1, and the preparation method comprises the following steps:

[0097] 1) The solid elemental sulfur is added to a heating kettle, and is heated to melt into liquid elemental sulfur at 160°C. The liquid elemental sulfur is subjected to fractional filtration to remove impurities with a particle size greater than 0.8 μm.

[0098] 2) The temperature of the heating kettle is increased and maintained at 180°C, and the undersize magnesite sieved through a 250-mesh sieve is added to the liquid elemental sulfur in the heating kettle; the temperature in the heating kettle is controlled at 180°C, and the mixture of magnesite and elemental sulfur is stirred and mixed at a frequency of 700 rpm for 150 s to obtain a uniform mixture.

[0099] 3) The dropping rate is maintained at 1.5 L·min -1 The above mixture is dropped into 20°C cooling water drop by drop, and is cooled and formed for 6 minutes to form solid spherical particles.

[0100] 4) Filtration, the solid spherical particles are placed in an oven and dried at 55°C for 24 h to obtain the sulfur-based autotrophic denitrification and phosphorus removal biological carrier containing magnesium, with a particle size of 3-4 mm.

[0101] Example 3

[0102] The sulfur-based autotrophic denitrification and phosphorus removal biological carrier containing magnesium provided in this example uses elemental sulfur and magnesite (magnesium carbonate content of about 90%) in a mass ratio of 4:1, and the preparation method is the same as that of Example 2, to obtain a sulfur-based autotrophic denitrification and phosphorus removal biological carrier containing magnesium, with a particle size of 3-4 mm.

[0103] Example 4

[0104] The sulfur-based autotrophic denitrification and phosphorus removal biological carrier containing magnesium provided in this example uses elemental sulfur and magnesite (magnesium carbonate content of about 90%) in a mass ratio of 1:1, and the preparation method comprises the following steps:

[0105] 1) Solid elemental sulfur is added to a heating kettle, and is heated and melted into liquid elemental sulfur at 120°C, and the liquid elemental sulfur is subjected to fractional filtration to remove impurities with a particle size greater than 0.8 μm.

[0106] 2) The temperature of the heating kettle is increased and maintained at 175°C, and the undersize magnesite sieved through a 160-mesh sieve is added to the liquid elemental sulfur in the heating kettle; the temperature in the heating kettle is controlled at 175°C, and the mixture of magnesite and elemental sulfur is stirred and mixed at a frequency of 400 rpm for 300 s to obtain a uniform mixture.

[0107] 3) The dropping rate is maintained at 1.5 L·min -1 The above mixture is dropped into 4°C cooling water drop by drop, and is cooled and formed for 10 min to form solid spherical particles.

[0108] 4) Filtration, the solid spherical particles are placed in an oven and dried at 60°C for 18 h to obtain the sulfur-based autotrophic denitrification and phosphorus removal biological carrier containing magnesium, with a particle size of 3-4 mm.

[0109] Example 5

[0110] The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided in this embodiment uses elemental sulfur and magnesite (magnesium carbonate content of about 90%) in a mass ratio of 1:4. The preparation method includes the following steps:

[0111] 1) Add solid elemental sulfur to a heating vessel and heat it at 180°C to melt it into liquid elemental sulfur. Then, filter the liquid elemental sulfur in stages to remove impurities with a particle size greater than 0.8 μm.

[0112] 2) The temperature of the heating vessel is maintained at 180℃. Magnesite that has been screened through a 300-mesh sieve is added to the liquid elemental sulfur in the heating vessel. The temperature inside the heating vessel is controlled at 180℃. The mixture of magnesite and sulfur is stirred at a frequency of 500 rpm for 200 seconds to obtain a uniform mixture.

[0113] 3) Maintain a drip rate of 1.5 L / min -1 The above mixture is added dropwise into cooling water at 50°C and cooled for 5 minutes to form solid spherical particles.

[0114] 4) Filtration: Place the solid spherical particles in an oven and dry them at 50°C for 42 hours to obtain the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier with a particle size of 3-4 mm.

[0115] like Figure 2 As shown in Figure (a), the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by this invention exhibits a nanoflower structure at the microscopic level. The interlayered lamellar structures create voids that give the material a large specific surface area and more active sites; as shown in Figure (a), the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by this invention exhibits a nanoflower structure at the microscopic level. Figure 2 The EDS results shown in (b) indicate that the carrier is based on elemental sulfur, and the nanoflowers embedded on it are mainly formed by doping most of the active materials with a small amount of elemental sulfur.

[0116] like Figure 3 The results show that the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier provided by the present invention contains polysulfides and linear sulfur forms that are easily taken up and utilized by microorganisms.

[0117] Example 6: A wastewater treatment method based on a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

[0118] A wastewater treatment method based on a sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier, employing, as follows: Figure 4 The wastewater treatment device shown includes an inlet device 1, a backwashing device 2, a backwashing air passage and an air inlet device 3, a filter plate support 4, packing material 5, an outlet 6, and a fixed bed filter 7.

[0119] An air inlet and a water inlet are provided at the bottom of the side wall of the fixed bed filter 7; the backwash air passage and air inlet device 3 are connected to the air inlet of the fixed bed filter 7; the water inlet device 1 is connected to the water inlet of the fixed bed filter 7; the backwash water inlet at the bottom of the fixed bed filter 7 is connected to the water outlet of the backwash device 2; the supporting filter plate 4 is placed inside the fixed bed filter 7; the supporting filter plate 4 is placed at the bottom of the side wall of the fixed bed filter 7 and is positioned above the air inlet and water inlet; the packing material 5 is placed on the supporting filter plate 4; and the water outlet 6 is provided on the top side wall of the fixed bed filter 7.

[0120] (I) Effects of sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biocarriers prepared at different dropping rates on the removal of nitrate nitrogen, ammonia nitrogen and total phosphorus

[0121] 1. A sulfur-based, magnesium-containing, autotrophic denitrification and phosphorus removal biological carrier, prepared as follows:

[0122] The sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carrier provided in this embodiment uses elemental sulfur and magnesite (magnesium carbonate content of about 90%) in a mass ratio of 1:1. The preparation method is the same as in Example 4, except that the dropping rate is controlled as shown in Table 1 to obtain sulfur-based magnesium-containing autotrophic denitrification and dephosphorization biological carriers prepared at different dropping rates.

[0123] 2. Methods for removing nitrate nitrogen, ammonia nitrogen, and total phosphorus

[0124] Sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carriers prepared at different dropping rates were used as filler material 5 and placed in a container as shown in Figure 5. Figure 4 In the fixed-bed filter 7 of the provided wastewater treatment device, the filling ratio is 70%. Anaerobic sludge from a wastewater treatment plant is added to the fixed-bed filter 7 and soaked for 24 hours before water flow is introduced for startup. During startup, the hydraulic retention time of the fixed-bed filter reactor is set to 1 hour. A peristaltic pump is used to stably deliver culture medium (containing nitrate nitrogen, ammonia nitrogen, and phosphorus, etc.) into the reactor for dynamic cultivation and acclimatization. Samples are taken and tested every 24 hours until the concentrations of nitrate nitrogen, ammonia nitrogen, and phosphorus in the effluent reach stability. The nitrate nitrogen concentration in the simulated wastewater is 30 mg / L. -1 The ammonia nitrogen concentration was 4 mg / L. -1 The total phosphorus concentration was 3.5 mg / L. -1 The influent pH was 7.52 ± 0.10. The concentrations of nitrate nitrogen, ammonia nitrogen, and total phosphorus in the effluent were measured, and the removal rates of nitrate nitrogen, ammonia nitrogen, and total phosphorus are shown in Table 1.

[0125] Table 1. Removal rates of nitrate nitrogen, ammonia nitrogen, and total phosphorus from sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carriers formed at different mixed droplet rates.

[0126]

[0127]

[0128] (II) Effects of different sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biocarriers on the removal of nitrate nitrogen, ammonia nitrogen and total phosphorus

[0129] 1. Comparative Example 1

[0130] The sulfur autotrophic denitrification and phosphorus removal biological carrier provided in this comparative example differs from Example 1 only in that it is composed solely of elemental sulfur as the matrix material, without the addition of active materials (alkaline magnesium compounds and / or minerals containing alkaline magnesium compounds).

[0131] 2. Comparative Example 2

[0132] This comparative example is Example 1 of the prior art CN109019877B.

[0133] 3. Methods for removing nitrate nitrogen, ammonia nitrogen, and total phosphorus

[0134] The autotrophic nitrogen and phosphorus removal biological carriers prepared in Examples 1-5, Comparative Examples 1 and 2 were respectively used as filler 5 and placed in a container as shown in the figure. Figure 4 In the fixed-bed filter 7 of the provided wastewater treatment device, the filling ratio is 70%. Anaerobic sludge from a wastewater treatment plant is added to the fixed-bed filter 7 and soaked for 24 hours before water flow is introduced for startup. During startup, the hydraulic retention time of the fixed-bed filter reactor is set to 1 hour. A peristaltic pump is used to stably deliver culture medium (containing nitrate nitrogen, ammonia nitrogen, and phosphorus, etc.) into the reactor for dynamic cultivation and acclimatization. Samples are taken and tested every 24 hours until the concentrations of nitrate nitrogen, ammonia nitrogen, and phosphorus in the effluent reach stability. The nitrate nitrogen concentration in the simulated wastewater is 30 mg / L. -1 The ammonia nitrogen concentration was 4 mg / L. -1 The total phosphorus concentration was 3.5 mg / L. -1 The influent pH was 7.52 ± 0.10. The concentrations of nitrate nitrogen, ammonia nitrogen, and total phosphorus in the effluent were measured, and the removal rates of nitrate nitrogen, ammonia nitrogen, and total phosphorus, as well as the effluent pH, are shown in Table 2.

[0135] Table 2. Removal rates of nitrate nitrogen, ammonia nitrogen, and total phosphorus, and effluent pH

[0136] Nitrate nitrogen removal rate Ammonia nitrogen removal rate Total phosphorus removal rate Effluent pH Example 1 80.7±3.9％ 52.1±3.1％ 22.5±1.4％ 7.31±0.11 Example 2 72.2±1.9％ 62.7±3.6％ 39.6±2.1％ 7.35±0.17 Example 3 90.9±3.2％ 85.6±4.2％ 60.1±4.2％ 7.35±0.12 Example 4 87.3±2.4％ 72.3±2.8％ 57.2±3.4％ 7.29±0.23 Example 5 92.1±2.2％ 98.1±1.5％ 70.1±3.6％ 7.31±0.14 Comparative Example 1 58.2±1.4％ Not removed 10.2±3.2％ 6.98±0.13 Comparative Example 2 84.3±5.7％ Not removed 76.0±8.0％ 7.01±0.11

[0137] In the process of continuous flow water, stable biofilm gradually grows on the surface of the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier, and the removal capacity of nitrate nitrogen and ammonia nitrogen gradually increases. Among them, the nitrate removal rate of the effluent of Example 5 is 92.1±2.2%, which is increased by 33.9% compared with the nitrate removal rate of Comparative Example 1, and the removal effect of nitrate removal rate is increased by 7.8% compared with Comparative Example 2; the ammonia nitrogen removal rate of the effluent of Example 5 is 98.1±1.5%, while Comparative Example 1 and Comparative Example 2 have no obvious removal of ammonia nitrogen; the total phosphorus removal rate of the effluent of Example 5 is 70.1±3.6%; the pH of the effluent of Example 5 can be maintained at 7.31±0.14, which is beneficial to the process of denitrification and phosphorus removal.

[0138] Therefore, when the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier of the application is filled in the fixed bed filter, the nanoflower structure of the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier gives it a large specific surface area and more active sites Figure 2 , and the released OH - , CO3 2- and other alkaline components can realize the automatic balance of pH, thereby facilitating the enrichment and growth of more microorganisms; the sulfur in the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier prepared by the method of the application is converted from zero-valent sulfur to polysulfide, and the circular sulfur is converted to linear sulfur Figure 3 , which is more conducive to the enrichment of denitrifying bacteria with reduced sulfur as electron donor, thereby giving the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier stable high denitrification efficiency. When the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier appears performance attenuation due to consumption, the bed layer can be restored to the original height by supplementing the prepared active biological carrier, without additional operations such as mixing.

[0139] The sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier provided by the application has high removal capacity for ammonia nitrogen and total phosphorus: when the sulfur-based magnesium-containing autotrophic nitrogen and phosphorus removal biological carrier provided by the application is used as filler to construct a packed bed, the dissolved free magnesium ions can promote the absorption and utilization of nitrifying bacteria to ammonia nitrogen by improving the transport efficiency of ammonia nitrogen into the cell; as shown in Figure 5 , the dissolved magnesium ions can combine with phosphate to form chemical precipitates to control the effluent phosphate. It has broad application prospects.

[0140] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions described in the foregoing examples, or make equivalent substitutions for part or all of the technical features; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A sulphur-based autotrophic denitrifying and phosphorus removing bio-carrier containing magnesium, characterized in that, The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier comprises a matrix material and active material distributed in the interior and / or at least part of the surface of the matrix material. The matrix material comprises elemental sulfur and sulfur-containing compounds. The active material comprises alkaline magnesium-containing compounds and / or minerals containing alkaline magnesium-containing compounds. The alkaline magnesium-containing compounds comprise magnesium carbonate and / or magnesium hydroxide; the minerals containing alkaline magnesium-containing compounds comprise magnesite, dolomite, brucite or serpentine. The mass ratio of the matrix material to the active material is 50:1-1:

8. The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier has a shape of a cluster, a block, a sphere-like shape or an irregular shape, and the maximum dimension is 1.5-12 mm. The preparation method of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier comprises the following steps: 1) Melting the matrix material into a liquid state at 120-180°C; 2) Mixing the matrix material in a molten state with the active material at 160-180°C, maintaining a stirring speed of 400-700 rpm for 30-300 s to obtain a uniform mixture; 3) control the dropping speed to be 0.5-5 L·min -1 The obtained mixed solution is dropped into cooling water at 4-60℃ drop by drop, and cooled and shaped for 1-10 min. 4) Filtering, and drying the obtained solid substance in an oven at 40-60°C for 12-48 h to obtain the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier.

2. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 1, characterized in that, The mass ratio of the matrix material to the active material is 10:1-1:

4.

3. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 1, characterized in that, The particle size of the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier is 2-6 mm.

4. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 1, characterized in that, The molten matrix material is subjected to impurity removal treatment before being mixed with the active material.

5. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 4, characterized in that, The impurity removal treatment specifically comprises: grading the molten matrix material to remove impurities ≥0.8 μm in the molten matrix material.

6. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 1, characterized in that, The active material is subjected to crushing and screening treatment before being mixed with the molten matrix material.

7. The sulfur-based autotrophic denitrifying and phosphorus-removing bio-carrier according to claim 6, characterized in that, The crushing and screening treatment specifically comprises: crushing the active material, passing it through a 60-300 mesh sieve, and taking the undersize.

8. A sewage treatment device based on a sulfur-based autotrophic denitrifying and phosphorus-removing biological carrier containing magnesium, characterized in that, The sewage treatment device comprises a packed bed or a fixed bed filter tank filled with packing material; the packing material comprises the sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier according to claim 1.

9. The sewage treatment device of claim 8, wherein, The packing material accounts for 10-90% of the volume of the fixed bed filter tank.

10. A method for wastewater treatment based on a sulfur-based autotrophic denitrifying and phosphorus-removing biological carrier containing magnesium, characterized in that, The sulfur-based magnesium-containing autotrophic denitrification and phosphorus removal biological carrier according to claim 1 is used for denitrification treatment and / or simultaneous removal of ammonia nitrogen and phosphate from sewage.

Images