A multi-stage AO process method for phosphorus and nitrogen removal from sewage

Abstract

The present invention relates to the field of sewage treatment, and provides a multi-stage AO process method for phosphorus and nitrogen removal from sewage. The water flows successively through anoxic zone 1, anaerobic zone, aerobic zone - anoxic zone 2 and sedimentation zone; the different zones are connected through notches, and the notches of adjacent zones are arranged staggered up and down; spiral biological fillers are suspended in anoxic zone 1 and aerobic zone. In the present invention, the notches of adjacent zones are arranged staggered up and down, so that the water flow passes through each zone in an S shape, prolonging the contact time in a limited space and improving the sewage treatment effect.

Description

Technical Field

[0001] The present invention relates to the field of sewage treatment, and particularly to a multi-stage AO process method for phosphorus and nitrogen removal from sewage. Background Art

[0002] The multi-stage AO process has become one of the important technologies in the field of sewage treatment. This process uses multi-stage contact oxidation (AO) technology to treat wastewater, achieving efficient phosphorus and nitrogen removal effects. For example, Patent CN112607862A discloses a multi-stage AO sewage biochemical treatment process: including a first-stage sewage biochemical treatment unit, a second-stage sewage biochemical treatment unit, and a third-stage sewage biochemical treatment unit connected in series in the direction of the sewage treatment process. The first-stage sewage biochemical treatment unit includes an anaerobic tank, an anoxic tank, an aerobic tank, and an internal reflux zone connected in sequence. The second-stage sewage biochemical treatment unit and the third-stage sewage biochemical treatment unit both include an anoxic / anaerobic tank, an aerobic tank, and an internal reflux zone connected in sequence. This invention forms a multi-stage A / O operation process with a concentration gradient through the alternating combination of anaerobic, anoxic, and aerobic conditions, deepening the removal of organic matter, strengthening biological phosphorus and nitrogen removal, especially strengthening biological nitrogen removal, and achieving high-quality effluent while reducing sludge production. However, there are many tanks and treatment units, resulting in a large floor area and high costs. Accordingly, an ideal solution is needed. Summary of the Invention

[0003] The present invention provides a multi-stage AO process method for phosphorus and nitrogen removal from sewage, in which the notches in adjacent areas are arranged staggered up and down, so that the water flows through each area in an S shape, extending the contact time within a limited space and improving the sewage treatment effect.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] A multi-stage AO process method for phosphorus and nitrogen removal from sewage, in which water flows through anoxic zone 1, anaerobic zone, aerobic zone - anoxic zone 2, and sedimentation zone in sequence; different zones are connected through notches, and the notches in adjacent zones are arranged staggered up and down; spiral biological fillers are suspended in anoxic zone 1 and the aerobic zone.

[0006] Preferably, there are at least 2 aerobic zone - anoxic zone 2s, which are arranged in series.

[0007] Preferably, the spiral biological filler includes an intermediate rope and a filler rope spirally wound around the intermediate rope. The filler rope is modified glass fiber, and the preparation method of the modified glass fiber is:

[0008] (1) Add octahydroxycage silsesquioxane monomer to an acrylic emulsion containing acrylic monomers to obtain a uniform mixture; the mass of the octahydroxycage silsesquioxane monomer is 0.5 - 2% of the mass of the emulsion;

[0009] (2) Take out the glass fiber after impregnating it in the mixture of (1), and cure and mold it.

[0010] Preferably, the components of the acrylic emulsion are: acrylic monomer, initiator, emulsifier, ethanol and water, and the solid content of the acrylic emulsion is 1-3%; the mass of the initiator is 2-6% of the acrylic monomer, and the mass of the emulsifier is 5-8% of the acrylic monomer.

[0011] Preferably, the particle size of the acrylic emulsion is 30-50 nm.

[0012] Preferably, the impregnation time is 6-14 h; the curing conditions are: drying at 80-100 °C for 20-60 min.

[0013] Preferably, anaerobic activated sludge is provided in the anaerobic zone, and facultative activated sludge is provided in the second anoxic zone.

[0014] Preferably, a vertical flow cylinder is provided in the center of the sedimentation zone, and hexagonal honeycomb inclined tube fillers are provided between the sedimentation zone and the vertical flow cylinder.

[0015] Preferably, an air aeration device is provided at the bottom of the first anoxic zone; an oxygen aeration device is provided at the bottom of the aerobic zone.

[0016] Therefore, the beneficial effects of the present invention are: the water quality flowing out from the outlet of the sedimentation zone meets the standards of CODcr, BOD5, ammonia nitrogen, SS and other indicators, and at the same time realizes the up-to-standard discharge of total nitrogen and total phosphorus; the total nitrogen removal rate is ≥85%, the total phosphorus removal rate is ≥90%, and the water quality treatment compliance rate is 100%. Description of the Drawings

[0017] Figure 1 is a flow chart of the multi-stage AO process method for phosphorus and nitrogen removal from sewage of the present invention.

[0018] In the figure: 1, the first anoxic zone, 11, the air aeration device, 2, the anaerobic zone, 21, the anaerobic activated sludge, 3, the aerobic zone, 31, the oxygen aeration device, 4, the second anoxic zone, 41, the facultative activated sludge, 5, the partition board, 6, the notch, 7, the sedimentation zone, 71, the vertical flow cylinder, 72, the hexagonal honeycomb inclined tube filler, 73, the water outlet, 74, the sludge outlet, 8, the spiral biological filler, 81, the middle rope, 82, the filler rope. Detailed Embodiments

[0019] The following further illustrates the technical solutions of the present invention through specific embodiments.

[0020] In the present invention, unless otherwise specified, the raw materials, equipment, etc. used can be obtained from the market or are commonly used in the art. The methods in the examples are conventional methods in the art unless otherwise specified. Unless otherwise indicated, all parts are by weight, the temperature is expressed in °C or at ambient temperature, and the pressure is atmospheric pressure or close to atmospheric pressure. There are various variants and combinations of reaction conditions (such as component concentrations, required solvents, solvent mixtures, temperature, pressure, and other reaction ranges) and conditions that can be used to optimize the purity and yield of the products obtained by the said methods, and only reasonable conventional experiments will be required to optimize such method conditions.

[0021] Example

[0022] A multi-stage AO process method for phosphorus and nitrogen removal from sewage, in which water flows successively through anoxic zone 1, anaerobic zone, aerobic zone - anoxic zone 2, and sedimentation zone. There are at least 2 aerobic zone - anoxic zone 2s, which are arranged in series. The different zones are connected by notches, and the notches of adjacent zones are staggered up and down, so that water can flow through each zone in an S shape, extending the contact time in a limited space and improving the sewage treatment effect.

[0023] Spiral biological fillers are suspended in anoxic zone 1, and an air aeration device is provided at the bottom. The spiral biological filler is composed of a middle rope and a filler rope spirally wound around the middle rope. The spiral structure makes the specific surface area of the filler large, and in practical applications, it can ensure sufficient film hanging space and sufficient biomass. The air aeration device at the bottom can increase the water body flow and increase the contact between sewage and spiral biological fillers. The three-dimensional spiral biological filler has a large-opening flow channel, which can reduce the flow resistance during rolling and rotation, and has good water permeability and water passing ability, and can maintain a relatively high flow rate and achieve material exchange and energy exchange.

[0024] Anaerobic activated sludge is provided in the anaerobic zone. Activated sludge is a flocculent sludge particle formed by the mixture of microbial populations such as bacteria, fungi, protozoa, and metazoans with suspended substances and colloidal substances in sewage. It has a strong ability to adsorb and decompose organic matter and good sedimentation performance, and is called activated sludge because of its biochemical activity. The complex microorganisms in the activated sludge form a complex food chain with the organic nutrients in the wastewater. The first to undertake the purification task are heterotrophic bacteria and saprophytic fungi, and bacteria, especially spherical bacteria, play the most crucial role. Well-operated activated sludge is a zoogloea composed of spherical bacteria with filamentous bacteria as the skeleton. It has good sedimentation performance. As the activated sludge operates normally, bacteria multiply in large numbers, and protozoa begin to grow. Protozoa are the primary predators of bacteria. Common protozoa in activated sludge include flagellates, ciliates, and suctorians. When the activated sludge is mature, sessile ciliates and species insects are dominant; metazoans are the secondary predators of bacteria. For example, rotifers and nematodes can only appear when the dissolved oxygen is sufficient. Therefore, when metazoans appear, it indicates that the treated water quality has improved.

[0025] There is spiral biological packing suspended in the aerobic zone, and an oxygen aeration device is provided at the bottom. The spiral biological packing is also composed of a middle rope and packing ropes spirally wound around the middle rope. The oxygen aeration device provides a continuous supply of oxygen to the aerobic zone.

[0026] There is facultative activated sludge in the second anoxic zone. Under anoxic conditions, facultative microorganisms degrade the refractory macromolecular organic matter in the wastewater, improving the biodegradability of the wastewater and significantly enhancing the aerobic degradation performance in the subsequent stage.

[0027] There is a vertical flow cylinder in the center of the sedimentation zone, and hexagonal honeycomb inclined tube packing is provided between the sedimentation zone and the vertical flow cylinder. The hexagonal honeycomb inclined tube packing is designed and developed based on the "shallow sedimentation" theory. This packing has a large wetted perimeter, a small hydraulic radius, good laminar flow state during operation, and the particle sedimentation is not interfered by turbulent flow, which can accelerate the separation of particles from water and shorten the sedimentation distance of particles.

[0028] Based on GB18918-2002 "Discharge Standard of Pollutants for Municipal Wastewater Treatment Plants", the water quality flowing out from the outlet of the sedimentation zone of the present invention meets the standards for CODcr, BOD5, ammonia nitrogen, SS and other indicators, and at the same time achieves the up-to-standard discharge of total nitrogen and total phosphorus. The total nitrogen removal rate is ≥85%, the total phosphorus removal rate is ≥90%, and the water quality compliance rate is 100%.

[0029] In order to improve the sewage treatment effect, the present invention further improves the packing rope. The packing rope is generally prepared from polyester and polypropylene materials, but it cannot have both mechanical properties and biological affinity. The present invention uses polypropylene containing octahydroxycage silsesquioxane monomer to coat glass fiber to obtain modified glass fiber. The packing rope made of modified glass fiber has high biological affinity, can increase the biomass adsorbed on the rope, and significantly extends the service life, reducing the replacement cost.

[0030] The preparation method of the modified glass fiber is as follows:

[0031] (1) Prepare acrylic emulsion

[0032] Using acrylic acid as the monomer, ethanol and water as the dispersion medium, under the action of an initiator and an emulsifier, prepare an acrylic emulsion with a particle size of 30-50 nm. The mass of the initiator is 2-6% of the acrylic acid monomer, and the mass of the emulsifier is 5-8% of the acrylic acid monomer. By adjusting the ratio of the emulsifier and the inoculation amount, the particle size of the emulsion can be controlled.

[0033] The specific preparation method of the acrylic emulsion can adopt any existing technology as long as the particle size is ensured to be within 30-50 nm. For example, the following steps are adopted in the embodiment: Add emulsifier Span 80 and allyloxyhydroxypropylsulfonic acid sodium to an ethanol aqueous solution with a volume ratio of 1:1, stir and heat to 70 °C; dissolve acrylic acid monomer and initiator AIBN in ethanol, and initiator K2 S 2 O 8 It was added dropwise to the above heating system together with an aqueous solution, and kept at 70 °C for 5 h; cooled to room temperature to obtain an acrylic emulsion.

[0034] (2) The acrylic emulsion prepared in step (1) was diluted to a solid content of 1-3%, and octahydroxycage silsesquioxane monomer accounting for 0.5-2% of the mass of the acrylic emulsion was added, and dispersed to obtain a uniform mixture. The octahydroxycage silsesquioxane monomer is an octameric silsesquioxane with 8 end groups all containing hydroxyl groups, such as the structure disclosed in patent CN103214510B.

[0035] (3) The glass fiber was impregnated in the mixture of (2) for 6-14 h and then taken out, and dried at 80-100 °C for 20-60 min for curing and forming to obtain modified glass fiber.

[0036] The glass fiber has the advantages of strong heat resistance, good corrosion resistance, high mechanical strength, etc. There are active groups such as amino groups and hydroxyl groups on the surface of the glass fiber. The octahydroxycage silsesquioxane monomer crosslinks with acrylic acid to form a network structure. There are relatively deep grooves on the surface of the uncoated glass fiber, and the grooves are relatively evenly distributed; through impregnation, the grooves on the surface of the glass fiber coated with the octahydroxycage silsesquioxane monomer and acrylic acid do not disappear, the groove depth becomes shallower, and it is relatively evenly distributed on the surface of the glass fiber. There is no phenomenon that the impregnated components agglomerate on the surface of the glass fiber and the coating fills the grooves. When these grooves act with polyacrylic acid, they can play an anchoring role.

[0037] Example 1

[0038] A multi-stage AO process method for phosphorus and nitrogen removal from sewage, such as Figure 1As shown, the sewage passes through the first anoxic zone 1, anaerobic zone 2, aerobic zone 3, second anoxic zone 4, second aerobic zone 3, second second anoxic zone 4, and sedimentation zone 7 in sequence. Different zones are separated by partition plates 5, and there are notches 6 on the partition plates 5. Different zones are connected through the notches 6, and the notches 6 of adjacent zones are staggered up and down. Water can flow through each zone in an S shape, extending the contact time within a limited space and improving the sewage treatment effect. Among them, a spiral biological filler 8 is suspended in the middle of the first anoxic zone 1, and an air aeration device 11 is provided at the bottom; the spiral biological filler 8 is composed of a middle rope 81 and a filler rope 82 spirally wound around the middle rope 81, and the filler rope 82 is a commercially available polypropylene filler rope. Anaerobic activated sludge 21 is provided in the anaerobic zone 2, and it is also equipped with an aeration device (not shown in the figure). A spiral biological filler 8 is also suspended in the middle of the aerobic zone 3, but the adsorbed organisms are different from those in the first anoxic zone 1; and an oxygen aeration device 31 is provided at the bottom. Facultative activated sludge 41 is provided in the second anoxic zone 4, and it is also equipped with an aeration device (not shown in the figure). The structures of the second aerobic zone 3 and the second second anoxic zone 4 are exactly the same as those of the aerobic zone 3 and the second anoxic zone 4. In practical applications, more groups of aerobic zones 3 and second anoxic zones 4 can be set in series. A vertical flow cylinder 71 is provided at the axial center of the sedimentation zone 7. Hexagonal honeycomb inclined tube fillers 72 are provided between the sedimentation zone 7 and the vertical flow cylinder 71. An outlet 73 is provided above the side wall of the sedimentation zone 7 for the treated water to flow out; the bottom of the sedimentation zone 7 is in an inverted cone shape, which is conducive to sludge enrichment. A sludge outlet 74 is provided at the bottom, and the sludge can be transported back to the anaerobic zone 2 or the second anoxic zone 4 for recycling.

[0039] Example 2

[0040] The difference from Example 1 is that the filler rope 82 is modified glass fiber.

[0041] The preparation method of the modified glass fiber is as follows:

[0042] (1) Prepare acrylic emulsion

[0043] Using acrylic acid as a monomer, ethanol and water as dispersion media, under the action of initiators (AIBN and K 2 S 2 O 8 ), emulsifiers (Span80 and allyloxyhydroxypropylsulfonate), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 4% of the acrylic acid monomer, and the mass of the emulsifier is 6% of the acrylic acid monomer.

[0044] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 2%, and add octahydroxycage silsesquioxane monomer with a mass of 1% of the acrylic emulsion, and disperse to obtain a uniform mixture.

[0045] (3) Immerse the glass fiber in the mixture of (2) for 10 h and then take it out, dry it at 90 °C for 40 min to cure and form, obtaining modified glass fiber.

[0046] Example 3

[0047] The difference from Example 2 is that the packing rope 82 is made of modified glass fiber.

[0048] The preparation method of the modified glass fiber is as follows:

[0049] (1) Prepare acrylic emulsion

[0050] Using acrylic acid as the monomer, ethanol and water as the dispersion medium, under the action of initiators (AIBN and K 2 S 2 O 8 ) and emulsifiers (Span80 and allyloxyhydroxypropylsulfonate sodium), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 2% of the acrylic acid monomer, and the mass of the emulsifier is 5% of the acrylic acid monomer.

[0051] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 1%, add octahydroxycage silsesquioxane monomer accounting for 0.5% of the mass of the acrylic emulsion, and disperse to obtain a uniform mixture.

[0052] (3) Immerse the glass fiber in the mixture of (2) for 6 h and then take it out, dry it at 100 °C for 20 min to cure and form, obtaining modified glass fiber.

[0053] Example 4

[0054] The difference from Example 2 is that the packing rope 82 is made of modified glass fiber.

[0055] The preparation method of the modified glass fiber is as follows:

[0056] (1) Prepare acrylic emulsion

[0057] Using acrylic acid as the monomer, ethanol and water as the dispersion medium, under the action of initiators (AIBN and K 2 S 2 O 8 ) and emulsifiers (Span80 and allyloxyhydroxypropylsulfonate sodium), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 6% of the acrylic acid monomer, and the mass of the emulsifier is 8% of the acrylic acid monomer.

[0058] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 3%, add octahydroxycage silsesquioxane monomer accounting for 2% of the mass of the acrylic emulsion, and disperse to obtain a uniform mixture.

[0059] (3) The glass fiber is taken out after being impregnated in the mixture of (2) for 14 h, dried at 80 °C for 60 min for curing and forming to obtain modified glass fiber.

[0060] Comparative example

[0061] Comparative example 1

[0062] The difference from Example 2 is that the solid content of the acrylic emulsion is higher than the preferred range and is 5%. Specifically as follows:

[0063] The preparation method of the modified glass fiber is as follows:

[0064] (1) Prepare acrylic emulsion

[0065] Using acrylic acid as a monomer, ethanol and water as dispersion media, and under the action of initiators (AIBN and K 2 S 2 O 8 ) and emulsifiers (Span80 and sodium allyloxyhydroxypropyl sulfonate), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 4% of the acrylic acid monomer, and the mass of the emulsifier is 6% of the acrylic acid monomer.

[0066] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 5%, add 1% of octahydroxycage silsesquioxane monomer based on the mass of the acrylic emulsion, and disperse to obtain a uniform mixture.

[0067] (3) The glass fiber is taken out after being impregnated in the mixture of (2) for 10 h, dried at 90 °C for 40 min for curing and forming to obtain modified glass fiber.

[0068] Comparative example 2

[0069] The difference from Example 2 is that octahydroxycage silsesquioxane monomer is not added. Specifically as follows:

[0070] The preparation method of the modified glass fiber is as follows:

[0071] (1) Prepare acrylic emulsion

[0072] Using acrylic acid as a monomer, ethanol and water as dispersion media, and under the action of initiators (AIBN and K 2 S 2 O 8 ) and emulsifiers (Span80 and sodium allyloxyhydroxypropyl sulfonate), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 4% of the acrylic acid monomer, and the mass of the emulsifier is 6% of the acrylic acid monomer.

[0073] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 2%.

[0074] (3) The glass fiber is taken out after being impregnated in the acrylic emulsion of (2) for 10 h, dried at 90 °C for 40 min for curing and forming to obtain modified glass fiber.

[0075] Comparative Example 3

[0076] The difference from Example 2 is that the octahydroxycage silsesquioxane monomer is replaced by octameric silsesquioxane with both end groups being hydrogen.

[0077] The preparation method of the modified glass fiber is as follows:

[0078] (1) Prepare acrylic emulsion

[0079] Using acrylic acid as the monomer, ethanol and water as the dispersion media, in the presence of initiators (AIBN and K 2 S 2 O 8 ), emulsifiers (Span80 and allyloxyhydroxypropylsulfonate sodium), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 4% of the acrylic acid monomer, and the mass of the emulsifier is 6% of the acrylic acid monomer.

[0080] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 2%, add 1% of octameric silsesquioxane (both end groups are hydrogen, molecular formula H 8 Si 8 O 12 ) based on the mass of the acrylic emulsion, and disperse to obtain a homogeneous mixture.

[0081] (3) The glass fiber is taken out after being impregnated in the mixture of (2) for 10 h, dried at 90 °C for 40 min for curing and forming to obtain modified glass fiber.

[0082] Comparative Example 4

[0083] The difference from Example 2 is that the dosage of the octahydroxycage silsesquioxane monomer is excessive, being 3% of the mass of the acrylic emulsion.

[0084] The preparation method of the modified glass fiber is as follows:

[0085] (1) Prepare acrylic emulsion

[0086] Using acrylic acid as the monomer, ethanol and water as the dispersion media, in the presence of initiators (AIBN and K 2 S 2 O 8 ), emulsifiers (Span80 and allyloxyhydroxypropylsulfonate sodium), prepare an acrylic emulsion with a particle size of 30 - 50 nm. The mass of the initiator is 4% of the acrylic acid monomer, and the mass of the emulsifier is 6% of the acrylic acid monomer.

[0087] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 2%, add octahydroxycage silsesquioxane monomer accounting for 3% of the mass of the acrylic emulsion, and disperse to obtain a homogeneous mixture.

[0088] (3) Immerse the glass fiber in the mixture of (2) for 10 h, then take it out and dry it at 90 °C for 40 min to cure and form, obtaining modified glass fiber.

[0089] Comparative Example 5

[0090] The difference from Example 2 is that the particle size of the acrylic emulsion is too small, being 10 nm. Specifically as follows:

[0091] The preparation method of the modified glass fiber is as follows:

[0092] (1) Prepare acrylic emulsion

[0093] Using acrylic acid as the monomer, ethanol and water as the dispersion medium, under the action of initiators (AIBN and K 2 S 2 O 8 ), prepare an acrylic emulsion with a particle size of 10 nm. The mass of the initiator is 4% of the acrylic monomer, and the mass of the emulsifier is 10% of the acrylic monomer.

[0094] (2) Dilute the acrylic emulsion prepared in step (1) to a solid content of 2%, add octahydroxycage silsesquioxane monomer accounting for 1% of the mass of the acrylic emulsion, and disperse to obtain a homogeneous mixture.

[0095] (3) Immerse the glass fiber in the mixture of (2) for 10 h, then take it out and dry it at 90 °C for 40 min to cure and form, obtaining modified glass fiber.

[0096] Performance test

[0097] Test the performance of the modified glass fiber of each example and comparative example, and the results are shown in the following table.

[0098]

[0099] As can be seen from the above table, compared with the commercially available packing rope in Example 1, the packing ropes prepared from the modified glass fiber in Examples 2-4 of the present invention have a faster film hanging speed and a larger film hanging amount. In terms of the sewage treatment effect, with the same treatment time and process, the total nitrogen removal rate and total phosphorus removal rate of the sewage in Examples 2-4 are also higher.

[0100] The properties of the modified glass fiber are greatly affected by its preparation method. Compared with Example 2:

[0101] (1) In Comparative Example 1, the solid content of the acrylic emulsion exceeded the preferred range, resulting in a decrease in the film hanging amount. After the solid content increased, the viscosity of the emulsion increased, and it was not easy for the emulsion to penetrate into the interior of the glass fiber during impregnation. There were relatively deep grooves on the surface of the uncoated glass fiber, and the grooves were relatively evenly distributed; after impregnation, the groove depth became shallower, which was not conducive to film hanging. In Comparative Example 4, the dosage of the octahydroxycage silsesquioxane monomer was too much, and the same reason led to a decrease in the effect. In Comparative Example 5, the emulsion particle size was too small to block the grooves, so the particle size of the emulsion should be within the preferred range.

[0102] (2) In Comparative Example 2, the octahydroxycage silsesquioxane monomer was not added. On the one hand, the octahydroxycage silsesquioxane monomer can improve the interfacial bonding force between polyacrylic acid and glass fiber. On the other hand, it can improve the surface morphology of the fiber, increase the surface roughness of the fiber, and increase the surface energy, which is beneficial to film hanging in a short time. In Comparative Example 3, octameric silsesquioxane with hydrogen at both end groups was used, and the effect was not as good as that of octameric silsesquioxane with hydroxyl at the end groups. Because acrylic acid has a carboxyl group, the hydroxyl group of the octahydroxycage silsesquioxane monomer can crosslink with acrylic acid to generate a network structure, promoting the above effects.

[0103] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes within the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A multi-stage AO process for removing phosphorus and nitrogen from sewage, characterized in that: Water flows through the anoxic zone 1, the anaerobic zone, the aerobic zone-anoxic zone 2 and the sedimentation zone in sequence; different zones are connected by gaps, and the gaps of adjacent zones are arranged alternately up and down; spiral biological fillers are suspended in the anoxic zone 1 and the aerobic zone; the spiral biological fillers include a middle rope and a filler rope spirally wound on the middle rope, and the filler rope is modified glass fiber; The preparation method of the modified glass fiber is as follows: (1) adding octahydroxy cage-shaped silsesquioxane monomer to an acrylic emulsion containing acrylic monomer to obtain a uniform mixture; the mass of the octahydroxy cage-shaped silsesquioxane monomer is 0.5-2% of the mass of the emulsion; (2) dipping the glass fiber in the mixture of (1), taking it out, and curing it into shape; The components of the acrylic emulsion are: acrylic monomer, initiator, emulsifier, ethanol and water. The solid content of the acrylic emulsion is 1-3%, and the particle size of the acrylic emulsion is 30-50 nm.

2. The multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, characterized in that: There are at least two aerobic zone-anoxic zone 2, which are arranged in series.

3. The multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, characterized in that: In the acrylic emulsion, the mass of the initiator is 2-6% of the acrylic monomer; the mass of the emulsifier is 5-8% of the acrylic monomer.

4. The multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, characterized in that: The immersion time is 6-14 h; the curing conditions are: 80-100 ℃, drying for 20-60 min.

5. The multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, characterized in that: Anaerobic activated sludge is arranged in the anaerobic zone, and facultative activated sludge is arranged in the anoxic zone 2.

6. The multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, characterized in that: A vertical flow tube is arranged in the center of the sedimentation area, and a hexagonal honeycomb inclined tube filler is arranged between the sedimentation area and the vertical flow tube.

7. A multi-stage AO process for removing phosphorus and nitrogen from sewage according to claim 1, 5 or 6, characterized in that: An air aeration device is provided at the bottom of the anoxic zone; an oxygen aeration device is provided at the bottom of the aerobic zone.

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