Multifunctional water treatment additive and method for its preparation

Abstract

The application relates to the technical field of sewage treatment materials, and discloses a multifunctional water treatment additive and a preparation method thereof, which is prepared from raw materials containing the following components by weight: primary powder 100 parts; 3-aminopropyl triethoxysilane 1.0-3.0 parts, calculated according to active ingredients; sodium gluconate 0.5-1.2 parts; polyaluminum chloride 2.0-4.0 parts, calculated according to the mass of aluminum oxide; and the primary powder is prepared by mixing 100 parts of industrial microsilica powder, 10-20 parts of calcium carbonate and 3-8 parts of sodium bicarbonate, and then high-temperature calcining at 750-800 DEG C. The material forms a calcium-silicon-based active structure and a positive electric surface, can provide sites for phosphate adsorption, complexation and precipitation removal, and can promote microbial adhesion as an inorganic carrier of a biochemical system, and improve sludge settling performance.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment materials technology, specifically to a multifunctional water treatment additive and its preparation method. Background Technology

[0002] The biological treatment of urban and industrial wastewater faces multiple water quality requirements, and treatment systems often operate under pressure to remove nitrogen and phosphorus. Activated sludge is also prone to slow settling when treating high-load wastewater. To maintain stable effluent quality, engineering projects typically require the addition of water treatment additives or inorganic carrier materials to the water body. These materials serve two purposes: firstly, to remove some pollutants from the water body, and secondly, to act as an inorganic framework to assist the biological system in maintaining the sludge-water separation process.

[0003] In current practical applications, natural limestone powder or conventional silica powder are commonly used as water treatment carriers. These basic mineral powders possess a certain degree of primary natural porosity, and after dispersion in water, they can remove some suspended particulate impurities through physical interception. Natural calcium-containing minerals can also release certain alkaline components when initially added to water bodies, which can be used to neutralize acidic industrial wastewater. These materials are relatively easy to obtain, and their initial preparation costs are relatively low.

[0004] However, the water quality in wastewater biological treatment systems often fluctuates significantly and has a complex composition, with some water bodies exhibiting persistently acidic characteristics. When conventional natural calcium-containing powders encounter acidic water, the surface alkaline earth metal components of the powder easily dissolve, eroding the original structure of the carrier. Metal binding sites used for phosphate precipitation are also gradually lost, making it difficult to sustain simultaneous adsorption and precipitation for phosphorus removal. Simultaneously, the extracellular polymers of microorganisms in wastewater are typically negatively charged, and conventional inorganic powders also tend to be negatively charged in the aqueous phase. When these two come into contact, interfacial repulsion easily occurs, making it difficult for bacterial cells to stably attach to the carrier surface, resulting in slow biomass accumulation during the initial startup phase. To improve carrier porosity, some existing processes attempt to use high-concentration acid for direct immersion and activation. However, this type of acid washing easily damages the internal mineral framework of the material, reducing the overall density of the carrier. After the inorganic powder with reduced density is mixed into the biological treatment tank, its physical weight-adding effect on sludge flocs is limited. When the system experiences high-load shocks, filamentous bacteria can still easily extend excessively beyond the flocs, leading to sludge bulking and deterioration of settling performance. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a multifunctional water treatment additive and its preparation method. This addresses the problems that existing natural calcium-containing powders or conventional silica powders, when used as water treatment carriers, suffer from easy leaching of calcium-containing active components, insufficient sustained phosphorus removal effect, unfavorable surface electrical properties for microbial adhesion, and limited improvement on sludge settling performance in biochemical systems.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a multifunctional water treatment additive, which adopts the following technical solution.

[0008] A multifunctional water treatment additive is prepared by compound modification of raw materials comprising the following parts by weight:

[0009] 100 parts of primary powder;

[0010] 1.0 to 3.0 parts of 3-aminopropyltriethoxysilane, based on the active ingredient;

[0011] Sodium gluconate 0.5 to 1.2 parts;

[0012] Polyaluminum chloride 2.0 to 4.0 parts, based on the mass of alumina.

[0013] The primary powder is prepared by mixing 100 parts by weight of industrial microsilica powder, 10 to 20 parts by weight of calcium carbonate and 3 to 8 parts by weight of sodium bicarbonate, and then calcining at a high temperature of 750°C to 800°C.

[0014] The composite modification includes: dispersing primary powder in water to form a suspension slurry, adding pre-hydrolyzed 3-aminopropyltriethoxysilane to the suspension slurry for a grafting reaction, adding sodium gluconate for a pretreatment reaction, adding polyaluminum chloride, and controlling the pH of the reaction system at 4.5-5.0 for modification reaction. After the reaction, the product is obtained by solid-liquid separation, washing, drying, pulverizing and sieving to obtain a multifunctional water treatment additive.

[0015] By employing the above technical solution, industrial microsilica powder, calcium carbonate, and sodium bicarbonate are calcined at high temperature to form primary powder. Sodium bicarbonate decomposes during calcination and participates in powder structure regulation, helping to improve the porosity of the calcined product. The alkaline component formed by the decomposition of sodium bicarbonate promotes the reaction between industrial microsilica powder and calcium carbonate at the solid-phase interface, resulting in the formation of a calcium-containing silicon-based active structure in the calcined product. This calcium-containing silicon-based active structure provides reaction sites for the adsorption, complexation, and precipitation of phosphates in subsequent water treatment processes.

[0016] 3-Aminopropyltriethoxysilane is pre-hydrolyzed to generate an active hydrolysis product containing silanol groups. When this hydrolysis product is added to a primary powder suspension, it undergoes a condensation reaction with the hydroxyl groups on the surface of the primary powder, forming an amino-containing organosilicon graft structure on the powder surface. This graft structure improves the interfacial state of the powder surface and provides interaction sites for the subsequent bonding of aluminum-containing modifying components.

[0017] Sodium gluconate molecules contain hydroxyl and carboxyl groups, which can coordinate with calcium-containing sites on the material surface. This pretreatment can reduce the apparent leaching level of calcium-containing components in the subsequent acid modification stage, thus helping to retain the calcium-containing active components in the material.

[0018] Polyaluminum chloride (PAC) forms positively charged aluminum-containing hydroxyl complexes or polyaluminum species in a weakly acidic environment with a pH of 4.5–5.0. This aluminum-containing component can bind to graft structures, hydroxyl sites, and surface sites after sodium gluconate pretreatment on the powder surface, resulting in a high positive Zeta potential in the finished material in an aqueous dispersion system. This positively charged surface facilitates interfacial interactions between the material and colloidal particles, phosphates, and extracellular polymers of microorganisms in water.

[0019] The resulting multifunctional water treatment additive possesses a calcium-silicon-based active structure, aluminum-modified components, and a porous inorganic framework. When added independently to treat phosphorus-containing water, this material can reduce the total phosphorus concentration in the water through adsorption, complexation, and precipitation. In wastewater biological treatment systems, this material can serve as an inorganic carrier core, providing interfacial sites for microbial attachment and facilitating the formation of denser composite floc structures, thereby improving sludge-water separation and reducing the risk of sludge bulking.

[0020] Preferably, the industrial microsilica powder contains ≥85wt% amorphous silica, D50 of 10μm~50μm, and specific surface area ≥15m². 2 / g; the basicity of polyaluminum chloride is 60%–85%.

[0021] By adopting the above technical solutions, the particle size, purity, and specific surface area of ​​industrial microsilica powder are limited to the aforementioned ranges, which is beneficial for maintaining slurry dispersibility and providing more surface contact sites. The basicity of polyaluminum chloride is limited to 60%–85%, which is beneficial for the bonding of aluminum-containing modified components on the powder surface and the formation of positively charged surfaces.

[0022] Preferably, the multifunctional water treatment additive is prepared from raw materials comprising the following parts by weight:

[0023] 100 parts of primary powder;

[0024] 2.0 to 2.5 parts of 3-aminopropyltriethoxysilane, based on the active ingredient;

[0025] Sodium gluconate 0.8 to 1.0 parts;

[0026] 3.0 to 3.5 parts of polyaluminum chloride, based on the mass of alumina;

[0027] The primary powder is prepared by mixing 100 parts by weight of industrial microsilica powder, 15 to 18 parts by weight of calcium carbonate and 5 to 6 parts by weight of sodium bicarbonate, and then calcining at a high temperature of 750°C to 800°C.

[0028] By adopting the above technical solution, the above ratio range can form a good synergistic relationship between the calcium-containing silicon-based active structure formed by calcination, the silane grafting structure, the sodium gluconate pretreatment effect and the polyaluminum chloride modification effect, so that the obtained material has the combined effects of total phosphorus removal performance, bio-adhesion performance and sedimentation improvement effect.

[0029] Secondly, the present invention provides a method for preparing a multifunctional water treatment additive, which adopts the following technical solution.

[0030] A method for preparing a multifunctional water treatment additive includes the following steps:

[0031] S1. Weigh industrial microsilica powder, calcium carbonate and sodium bicarbonate according to the weight ratio, put them into a mixer and mix evenly. Then, send them into a rotary kiln for high-temperature calcination. The material is naturally cooled to room temperature with the kiln to obtain primary powder.

[0032] S2. The primary powder obtained in step S1 is added to deionized water and dispersed to prepare a suspension slurry. 3-aminopropyltriethoxysilane that has been pre-hydrolyzed is slowly added dropwise and a constant-temperature stirring grafting reaction is carried out.

[0033] S3. Keeping the temperature and stirring state of the reaction system in step S2 unchanged, add sodium gluconate in solid form to the reaction system for isothermal pretreatment reaction.

[0034] S4. Keeping the temperature of the reaction system in step S3 constant, add liquid polyaluminum chloride dropwise to the reaction system for isothermal modification reaction. At the same time, use acidic or alkaline aqueous solution to slowly add and adjust the pH value of the reaction system to control it between 4.5 and 5.0.

[0035] S5. The liquid material after the reaction in step S4 is subjected to solid-liquid separation. The collected filter cake is washed and then sent to a dryer to dry. After being crushed and sieved, the multifunctional water treatment additive is obtained.

[0036] By employing the above technical solution, the preparation method sequentially includes high-temperature calcination, silane grafting, sodium gluconate pretreatment, and weakly acidic modification with polyaluminum chloride. This sequence of steps reduces the leaching of calcium-containing components during the acidic modification stage and allows the aluminum-containing modified components to bind to the powder surface, thereby forming a water treatment additive with a calcium-containing silicon-based active structure and a positively charged surface.

[0037] Preferably, in step S1, the specific process of high-temperature calcination is as follows: the temperature is increased to 750℃~800℃ at a heating rate of 5℃ / min~10℃ / min, and then calcined at 750℃~800℃ for 1.5h~2.5h.

[0038] By adopting the above technical solution, the above calcination conditions can coordinate the sodium bicarbonate decomposition process with the powder calcination process, which is conducive to the formation of a loose powder structure and a calcium-silicon-based active structure, while avoiding excessive sintering of the powder due to excessively high temperature.

[0039] Preferably, in step S2, the solid content of the suspension slurry is controlled at 10wt% to 20wt%; before the drop addition, the pre-hydrolysis treatment is carried out by mixing 3-aminopropyltriethoxysilane with deionized water and hydrolyzing for 15min to 30min; the temperature of the constant temperature stirring grafting reaction is controlled at 60℃ to 70℃, and the reaction time is 1h to 1.5h.

[0040] By adopting the above technical solution, limiting the solid content to 10wt%–20wt% is beneficial for balancing slurry flowability and powder contact efficiency. Controlling the hydrolysis time to 15min–30min helps improve the hydrolytic activity of silane molecules and reduce self-polymerization reactions during the hydrolysate's storage process. A reaction temperature of 60℃–70℃ and a reaction time of 1h–1.5h facilitate grafting reactions between silane molecules and the powder surface.

[0041] Preferably, in step S3, the temperature of the isothermal pretreatment reaction is controlled at 60℃~70℃, and the reaction time is 30min~60min.

[0042] By adopting the above technical solution, the temperature and time conditions are conducive to the dissolution and diffusion of sodium gluconate in the suspension slurry, and its interaction with calcium-containing sites on the surface of the material, thereby reducing the apparent leaching rate of calcium in the subsequent acid modification stage.

[0043] Preferably, in step S4, pH online monitoring is activated simultaneously with the addition of polyaluminum chloride; the temperature of the isothermal modification reaction is controlled at 60℃~70℃, and the reaction time is 1.5h~2.5h. The acidic aqueous solution is a hydrochloric acid aqueous solution with a mass fraction of 5wt%~10wt%; the alkaline aqueous solution is a sodium hydroxide aqueous solution with a mass fraction of 5wt%~10wt%.

[0044] By adopting the above technical solution and adjusting the pH using an acidic or alkaline aqueous solution with a mass fraction of 5wt%–10wt%, local pH fluctuations can be reduced. Controlling the pH of the reaction system at 4.5–5.0 and reacting at 60℃–70℃ for 1.5h–2.5h facilitates the bonding of the aluminum-containing modified components with the grafted structure on the powder surface, forming a positively charged surface.

[0045] Preferably, in step S5, the drying temperature is 105℃~110℃, and the material is dried until the residual moisture content is ≤5wt%.

[0046] By adopting the above technical solution, the above drying conditions can remove moisture from the finished material and reduce the risk of powder agglomeration, which is beneficial to maintaining the powder flowability and storage stability of the finished product.

[0047] This invention provides a multifunctional water treatment additive and its preparation method. It has the following beneficial effects:

[0048] 1. This invention involves mixing sodium bicarbonate, calcium carbonate, and industrial microsilica powder, followed by high-temperature calcination. This process induces a solid-phase interfacial reaction during pyrolysis and pore formation, resulting in a calcium-silica-based active structure. This enhances the porosity of the material and provides reaction sites for the adsorption, complexation, and precipitation removal of phosphates in water. Compared to directly using natural inorganic minerals or simple blends as water treatment carriers, this invention improves the reactivity and phosphorus removal function of inorganic carriers.

[0049] 2. This invention employs a technical solution combining silane coupling agent grafting and weakly acidic modification with polyaluminum chloride. This forms an amino-containing grafted structure and an aluminum-containing modified component on the material surface, improving the surface charge and interfacial bonding ability. This enhances the material's interfacial interaction with negatively charged colloidal particles, phosphates, and microbial extracellular polymers, thereby improving pollutant removal capacity and microbial adhesion performance. Compared to conventional inorganic carriers with weak surface charge and lacking a stable modified layer, this invention is more beneficial for bioaccumulation during the start-up phase of biochemical systems.

[0050] 3. In this invention, sodium gluconate is added before the acid modification of polyaluminum chloride to pretreat the calcium-containing primary powder. This reduces the apparent leaching level of calcium in the subsequent acid modification stage, which is beneficial to retain the calcium-containing active components and inorganic framework structure in the material. After the resulting material is added to the biochemical system, it can serve as the inorganic support core of the composite floc, improve the density of sludge floc, improve the sludge-water separation effect, and reduce the risk of sludge bulking under high load and low dissolved oxygen conditions. Attached Figure Description

[0051] Figure 1 This is a schematic diagram of the process flow for preparing the multifunctional water treatment additive of the present invention.

[0052] Figure 2 The images show a comparison of X-ray powder diffraction patterns of the primary powders prepared in step S1 of Example 1 and Comparative Example 1, where (a) is the X-ray powder diffraction pattern of the primary powders prepared in step S1 of Example 1, and (b) is the X-ray powder diffraction pattern of the primary powders prepared in step S1 of Comparative Example 1.

[0053] Figure 3The images show a comparison of the microscopic morphology of sludge flocs in the composite biochemical system of Example 1 group and the blank control group. (a) is a microscopic morphology image of sludge flocs in the blank control group, and (b) is a microscopic morphology image of composite sludge flocs in Example 1 group. Detailed Implementation

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0055] The sources and specifications of the main raw materials and reagents used in the following examples and comparative examples are as follows. Unless otherwise specified, all reagents are commercially available analytical grade or higher products.

[0056] Industrial microsilica powder, with amorphous silica as the main component, CAS number 69012-64-2, amorphous silica mass fraction ≥85wt%, D50 of 10μm to 50μm, specific surface area ≥15m². 2 / g.

[0057] 3-Aminopropyltriethoxysilane, with the molecular formula C9H 23 NO3Si, CAS number 919-30-2, active ingredient purity ≥98wt.

[0058] Sodium gluconate, with the molecular formula C6H 11 NaO7, CAS number 527-07-1, purity ≥98wt%.

[0059] Polyaluminum chloride, with the general formula (Al2(OH)2) n Cl 6-n ) m CAS No. 1327-41-9, industrial grade liquid, with a mass fraction of 10wt% to 12wt% based on alumina and a basicity of 60% to 85%.

[0060] Calcium carbonate, with the molecular formula CaCO3 and CAS number 471-34-1, is of industrial grade, with a purity ≥95wt% and a particle size not exceeding 400 mesh.

[0061] Sodium bicarbonate, with the molecular formula NaHCO3 and CAS number 144-55-8, is an industrial grade product with a purity of ≥98wt%.

[0062] Hydrochloric acid, in the form of an aqueous solution with a mass fraction of 5 wt% to 10 wt%.

[0063] The sodium hydroxide solution is an aqueous solution of sodium hydroxide with a mass fraction of 5 wt% to 10 wt%.

[0064] Example 1:

[0065] This embodiment provides a multifunctional water treatment additive, as described above. Figure 1 Its preparation method includes the following steps.

[0066] S1. Weigh 100g of industrial microsilica powder, 15g of calcium carbonate, and 5g of sodium bicarbonate, and put them into a three-dimensional mixer. Mix at room temperature for 30 minutes. Feed the mixed powder into a rotary kiln and heat it to 780℃ at a heating rate of 8℃ / min. Then, keep it at 780℃ for 2 hours. After calcination, allow the material to cool naturally to room temperature with the kiln to obtain the primary powder.

[0067] S2. Weigh 100g of the primary powder obtained in S1 and transfer it to a reactor equipped with a temperature-controlled jacket and a mechanical stirrer. Add deionized water to prepare a suspension slurry with a solid content of 15wt%. Start stirring and maintain the temperature of the slurry system in the reactor at 65℃ using jacket heating. Pre-hydrolyze 3-aminopropyltriethoxysilane with an appropriate amount of deionized water for 20 minutes, then slowly add it dropwise to the reactor. The total amount of the active ingredient 3-aminopropyltriethoxysilane added is 2.0g. After the addition is complete, continue stirring at 65℃ for 1.5 hours.

[0068] S3. Keep the temperature inside the reactor at 65℃ and the stirring state unchanged. Add 0.8g of sodium gluconate solid to the system and maintain the constant temperature and stirring for 45min.

[0069] S4. Maintain the temperature inside the reactor at 65℃, and add liquid polyaluminum chloride dropwise to the system, with the amount added being 3.0 g based on the mass of alumina. Simultaneously, activate the online pH monitoring system and slowly add a 5wt% to 10wt% hydrochloric acid aqueous solution to adjust the pH value of the slurry system in the reactor to 4.8. Under these temperature and pH conditions, maintain the reaction temperature and stir for 2 hours.

[0070] S5. Pump the liquid from reaction S4 into a plate and frame filter press for solid-liquid separation, and wash the filter cake with clean water. Send the washed filter cake into a dryer, controlling the drying temperature at 108℃, and dry until the residual moisture content of the material is less than or equal to 5 wt%. The dried material is then mechanically pulverized and passed through a 100-mesh sieve to obtain the finished multifunctional water treatment additive.

[0071] Example 2:

[0072] This embodiment provides a multifunctional water treatment additive, the preparation method of which includes the following steps.

[0073] S1. Weigh 100g of industrial microsilica powder, 10g of calcium carbonate, and 3g of sodium bicarbonate, and put them into a three-dimensional mixer. Mix at room temperature for 20 minutes. Feed the mixed powder into a rotary kiln and heat it to 750℃ at a heating rate of 5℃ / min. Then, calcine it at 750℃ for 1.5 hours. After calcination, allow the material to cool naturally to room temperature with the kiln to obtain the primary powder.

[0074] S2. Weigh 100g of the primary powder obtained in S1 and transfer it to a reactor equipped with a temperature-controlled jacket and a mechanical stirrer. Add deionized water to prepare a suspension slurry with a solid content of 10wt%. Start stirring and maintain the temperature of the slurry system in the reactor at 60℃ using jacket heating. Pre-hydrolyze 3-aminopropyltriethoxysilane with an appropriate amount of deionized water for 15 minutes, then slowly add it dropwise to the reactor. The total amount of the active ingredient 3-aminopropyltriethoxysilane added is 1.0g. After the addition is complete, continue stirring at 60℃ for 1 hour.

[0075] S3. Keep the temperature inside the reactor at 60℃ and the stirring state unchanged. Add 0.5g of sodium gluconate solid to the system and maintain constant temperature and stirring for 30min.

[0076] S4. Maintain the temperature inside the reactor at 60℃, and add liquid polyaluminum chloride dropwise to the system, with the amount added being 2.0 g based on the mass of alumina. Simultaneously, activate the online pH monitoring system and slowly add a 5wt% to 10wt% hydrochloric acid solution to adjust the pH value of the slurry system in the reactor to 4.5. Under these temperature and pH conditions, maintain the reaction temperature and stir for 1.5 hours.

[0077] S5. Pump the liquid from reaction S4 into a plate and frame filter press for solid-liquid separation, and wash the filter cake with clean water. Send the washed filter cake into a dryer, controlling the drying temperature at 105℃, and dry until the residual moisture content of the material is less than or equal to 5 wt%. The dried material is then mechanically pulverized and passed through a 100-mesh sieve to obtain the finished multifunctional water treatment additive.

[0078] Example 3:

[0079] This embodiment provides a multifunctional water treatment additive, the preparation method of which includes the following steps.

[0080] S1. Weigh 100g of industrial microsilica powder, 20g of calcium carbonate, and 8g of sodium bicarbonate, and put them into a three-dimensional mixer. Mix at room temperature for 40 minutes. Feed the mixed powder into a rotary kiln and heat it to 800℃ at a heating rate of 10℃ / min. Then, calcine it at 800℃ for 2.5 hours. After calcination, allow the material to cool naturally to room temperature with the kiln to obtain the primary powder.

[0081] S2. Weigh 100g of the primary powder obtained in S1 and transfer it to a reactor equipped with a temperature-controlled jacket and a mechanical stirrer. Add deionized water to prepare a suspension slurry with a solid content of 20wt%. Start stirring and maintain the temperature of the slurry system in the reactor at 70℃ using jacket heating. Pre-hydrolyze 3-aminopropyltriethoxysilane with an appropriate amount of deionized water for 30 minutes, then slowly add it dropwise to the reactor. The total amount of the active ingredient 3-aminopropyltriethoxysilane added is 3.0g. After the addition is complete, continue stirring at 70℃ for 1.5 hours.

[0082] S3. Keep the temperature inside the reactor at 70℃ and the stirring state unchanged. Add 1.2g of sodium gluconate solid to the system and maintain constant temperature and stirring for 60min.

[0083] S4. Maintain the temperature inside the reactor at 70℃, and add liquid polyaluminum chloride dropwise to the system, with the amount added being 4.0 g based on the mass of alumina. Simultaneously, activate the online pH monitoring system and slowly adjust the pH of the slurry system inside the reactor by adding a 5wt% to 10wt% hydrochloric acid aqueous solution or a 5wt% to 10wt% sodium hydroxide aqueous solution, maintaining the pH at 5.0. Under these temperature and pH conditions, maintain the temperature and stir the reaction for 2.5 hours.

[0084] S5. Pump the liquid from reaction S4 into a plate and frame filter press for solid-liquid separation, and wash the filter cake with clean water. Send the washed filter cake into a dryer, controlling the drying temperature at 110℃, and dry until the residual moisture content of the material is less than or equal to 5 wt%. The dried material is then mechanically pulverized and passed through a 100-mesh sieve to obtain the finished multifunctional water treatment additive.

[0085] Example 4:

[0086] This embodiment provides a multifunctional water treatment additive, the preparation method of which includes the following steps.

[0087] S1. Weigh 100g of industrial microsilica powder, 18g of calcium carbonate, and 6g of sodium bicarbonate, and put them into a three-dimensional mixer. Mix at room temperature for 30 minutes. Feed the mixed powder into a rotary kiln and heat it to 790℃ at a heating rate of 8℃ / min. Then, keep it at 790℃ for 2 hours. After calcination, allow the material to cool naturally to room temperature with the kiln to obtain the primary powder.

[0088] S2. Weigh 100g of the primary powder obtained in S1 and transfer it to a reactor equipped with a temperature-controlled jacket and a mechanical stirrer. Add deionized water to prepare a suspension slurry with a solid content of 15wt%. Start stirring and maintain the temperature of the slurry system in the reactor at 65℃ using jacket heating. Pre-hydrolyze 3-aminopropyltriethoxysilane with an appropriate amount of deionized water for 20 minutes, then slowly add it dropwise to the reactor. The total amount of the active ingredient 3-aminopropyltriethoxysilane added is 2.5g. After the addition is complete, continue stirring at 65℃ for 1 hour.

[0089] S3. Keep the temperature inside the reactor at 65℃ and the stirring state unchanged. Add 1.0g of sodium gluconate solid to the system and maintain the constant temperature and stirring for 45min.

[0090] S4. Maintain the temperature inside the reactor at 65℃, and add liquid polyaluminum chloride dropwise to the system at a rate of 3.5g based on the mass of alumina. Simultaneously, activate the online pH monitoring system and slowly add a 5wt% to 10wt% hydrochloric acid solution to adjust the pH of the slurry system in the reactor to 4.7. Under these temperature and pH conditions, maintain the reaction temperature and stir for 2 hours.

[0091] S5. Pump the liquid from reaction S4 into a plate and frame filter press for solid-liquid separation, and wash the filter cake with clean water. Send the washed filter cake into a dryer, controlling the drying temperature at 106℃, and dry until the residual moisture content of the material is less than or equal to 5 wt%. The dried material is then mechanically pulverized and passed through a 100-mesh sieve to obtain the finished multifunctional water treatment additive.

[0092] Comparative Example 1:

[0093] Compared with Example 1, the difference is that sodium bicarbonate is not added in step S1, and industrial microsilica powder is mixed with calcium carbonate and then calcined. Other steps and process conditions are the same as in Example 1.

[0094] Comparative Example 2:

[0095] Compared with Example 1, the difference is that the high-temperature calcination process in step S1 is omitted. Instead, the physical mixed powder obtained by mixing industrial microsilica powder, calcium carbonate and sodium bicarbonate according to the amount used in step S1 of Example 1 is used for liquid phase dispersion in step S2. Other steps and process conditions are the same as in Example 1.

[0096] Comparative Example 3:

[0097] Compared with Example 1, the difference is that step S3 is omitted, that is, sodium gluconate is not added for pre-complexation passivation, and after step S2, the acidic crosslinking anchoring in step S4 is directly performed. Other steps and process conditions are the same as in Example 1.

[0098] Comparative Example 4:

[0099] Compared with Example 1, the difference lies in the change of the reaction order of steps S3 and S4. That is, after step S2, polyaluminum chloride is added dropwise first and the pH value is adjusted to 4.8 to carry out the reaction, and then sodium gluconate is added to carry out the reaction. Other steps and process conditions are the same as in Example 1.

[0100] Comparative Example 5:

[0101] Compared with Example 1, the difference is that in step S4, sodium hydroxide solution is used to adjust and control the pH value of the slurry system in the reactor to 7.0 instead of 4.8. Other steps and process conditions are the same as in Example 1.

[0102] Comparative Example 6:

[0103] Compared with Example 1, the difference is that the 3-aminopropyltriethoxysilane dropwise addition process in step S2 is omitted, while the other steps and process conditions are the same as in Example 1.

[0104] Test Example 1:

[0105] Test objective: To investigate the effect of sodium bicarbonate addition on the X-ray powder diffraction characteristics of industrial microsilica powder and calcium carbonate powder after calcination, and to provide characterization basis for the formation of calcium-containing silicon-based active structures in primary powders.

[0106] The testing steps are as follows:

[0107] 1. The primary powder obtained in step S1 of Example 1 and the primary powder obtained in step S1 of Comparative Example 1 were used as test objects.

[0108] 2. Grind the two primary powders separately in an agate mortar, pass them through a 200-mesh standard sieve, and collect the powder that passes through the sieve for later use.

[0109] 3. The sieved powder sample was placed in a quartz glass sample cell and tested using an X-ray powder diffractometer. The test conditions were Cu target Kα radiation, tube voltage 40kV, tube current 40mA, scanning range 2θ from 10° to 80°, scanning step size 0.02°, and scanning speed 5° / min.

[0110] 4. Record the X-ray powder diffraction pattern and select characteristic positions near 2θ=22.3°, 2θ=29.4° and 2θ=32.6° for peak intensity comparison.

[0111] The test results are shown in Table 1 and Figure 2 .

[0112] Table 1: Comparison of characteristic X-ray diffraction peak intensities of primary powders from Example 1 and Comparative Example 1

[0113] Test sample Peak intensity (au) at 2θ = 22.3 degrees Peak intensity (au) at 2θ = 29.4 degrees Peak intensity (au) at 2θ = 32.6 degrees Primary powder in step S1 of Comparative Example 1 498 1876 45 In Example 1, step S1, primary powder 512 183 423

[0114] From Table 1 and Figure 2 It can be seen that the primary powder obtained in step S1 of Comparative Example 1 has a strong diffraction peak near 2θ = 29.4°, which corresponds to the characteristic diffraction peak of crystalline calcium carbonate. Comparative Example 1 did not add sodium bicarbonate for calcination, yet the calcined product still retained relatively obvious diffraction characteristics of calcium carbonate crystals, indicating that the degree of solid-phase reaction between industrial microsilica powder and calcium carbonate is relatively low.

[0115] In Example 1, the peak intensity of the primary powder obtained in step S1 decreased from 1876 to 183 near 2θ = 29.4°, while broadening diffraction characteristics appeared near 2θ = 32.6°. Combined with... Figure 2 The changes in the overall diffraction curves within the range of 10° to 80° show that after adding sodium bicarbonate and calcining, the diffraction characteristics of calcium carbonate-related crystals in the primary powder are significantly weakened, and the phase composition and microstructure of the calcined product change.

[0116] The above test results indicate that the addition of sodium bicarbonate can alter the diffraction characteristics of the industrial microsilica powder and calcium carbonate calcination system, providing a characterization basis for the formation of calcium-containing silicon-based active structures in the calcination products. These calcium-containing silicon-based active structures can provide active sites for phosphate adsorption, complexation, or precipitation removal in subsequent water treatment processes.

[0117] Test Example 2:

[0118] Test objective: To evaluate the effect of sodium gluconate pretreatment on the leaching behavior of calcium-containing components in the material during the acid crosslinking stage.

[0119] The testing steps are as follows:

[0120] 1. The slurries after the cross-linking and anchoring reaction in step S4 of Examples 1 to 4, Comparative Examples 3 and 4 were used as test objects.

[0121] 2. After the reaction in step S4 is completed, immediately remove two equal volumes of suspension slurry, 50 mL each, from the reactor; one portion is vacuum filtered using a polyethersulfone microporous membrane with a pore size of 0.22 μm, and the filtrate is collected as the filtrate to be tested; the other portion is not subjected to solid-liquid separation and is used as the slurry total calcium test sample.

[0122] 3. Accurately transfer 10 mL of the filtrate to be tested into a beaker, add 5% nitric acid solution for acidification, cool, and then dilute to 100 mL in a volumetric flask to obtain the calcium determination solution of the filtrate; take an equal volume of the original slurry sample, digest it with nitric acid until the solid is completely dispersed or dissolved, and then dilute to obtain the total calcium determination solution of the slurry.

[0123] 4. The calcium concentration in the filtrate calcium determination solution and the slurry total calcium determination solution were measured using inductively coupled plasma atomic emission spectrometry (ICP-AES). Based on the mass of calcium in the filtrate sample (m1) and the total mass of calcium in an equal volume of the original slurry (m2), the apparent calcium leaching rate was calculated using the following formula:

[0124] Apparent leaching rate of calcium = m1 / m2 × 100%.

[0125] The test data is shown in Table 2.

[0126] Table 2: Results of Apparent Leaching Rate of Calcium in the Reaction Systems of Examples and Comparative Examples

[0127] Test sample group Calcium concentration in the filtrate (mg / L) Calculation of calcium concentration (mg / L) for an equal volume of original slurry digestate. Apparent leaching rate of calcium (%) Example 1 284.6 9063.7 3.14 Example 2 179.2 6243.97 2.87 Example 3 511.3 11835.6 4.32 Example 4 387.9 10627.4 3.65 Comparative Example 3 8104.5 9064.4 89.41 Comparative Example 4 7448.2 9064.4 82.17

[0128] As shown in Table 2, the apparent calcium leaching rates of Examples 1 to 4 ranged from 2.87% to 4.32%, while the apparent calcium leaching rates of Comparative Examples 3 and 4 were 89.41% and 82.17%, respectively. Compared with Comparative Examples 3 and 4, the apparent calcium leaching rates of Examples 1 to 4 were significantly reduced during the acidic crosslinking stage.

[0129] Comparative Example 3, without sodium gluconate pretreatment, showed a high calcium concentration in the filtrate under subsequent acidic crosslinking conditions, indicating a high leaching level of the calcium-containing components in the material under these conditions. Comparative Example 4, by altering the order of addition of sodium gluconate and polyaluminum chloride, adding sodium gluconate after the acidic crosslinking reaction, still maintained a high apparent calcium leaching rate, demonstrating that the order of addition affects the retention of calcium-containing components in the acidic system.

[0130] In Examples 1 through 4, sodium gluconate was added for pretreatment before the acidic crosslinking of polyaluminum chloride, and the apparent leaching rate of calcium remained low. This result indicates that sodium gluconate pretreatment can reduce the apparent leaching level of calcium-containing components in the material during the acidic crosslinking stage, which is beneficial for retaining the calcium-containing active components in the material. The retained calcium-containing active components can provide reaction sites for phosphate adsorption, complexation, or precipitation removal in subsequent water treatment processes.

[0131] Test Example 3:

[0132] Test objective: To investigate the effect of polyaluminum chloride treatment under different pH crosslinking conditions on the surface potential of the material.

[0133] The testing steps are as follows:

[0134] 1. The multifunctional water treatment additive products prepared in Example 1 and Comparative Example 5 were used as test subjects.

[0135] 2. Weigh 0.1g of the finished powder from Example 1 and Comparative Example 5 respectively, add them to 100mL of deionized water, and use an ultrasonic cell disruptor to ultrasonically disperse them for 10min at 200W power to obtain a suspension with a mass concentration of 1mg / mL.

[0136] 3. After the suspension has stood for 3 minutes, use a syringe to draw up the middle layer of suspension and inject it into the U-shaped capillary sample cell with a platinum electrode.

[0137] 4. Place the sample cell in the microelectrophoresis chamber, set the test temperature to 25℃, and the equilibration time to 120s.

[0138] 5. Start the instrument to measure electrophoretic mobility and calculate the Zeta potential value based on the Smoluchovsky equation. Perform five parallel tests on each group of samples under the same testing conditions, record the results, and calculate the mean and standard deviation.

[0139] The test data is shown in Table 3.

[0140] Table 3: Zeta potential test results of the aqueous dispersion systems of the final products of Example 1 and Comparative Example 5

[0141] Test sample group First measurement (mV) Second measurement (mV) Third measurement (mV) Fourth measurement (mV) Fifth measurement (mV) Mean ± Standard Deviation (mV, n=5) Example 1 +38.6 +41.2 +37.1 +40.5 +39.3 39.34±1.61 Comparative Example 5 -3.5 +1.2 -1.8 -4.1 -0.6 -1.76±2.16

[0142] As shown in Table 3, the five Zeta potential test values ​​of Example 1 were all in the positive range, with an average value of +39.34 mV. The five Zeta potential test values ​​of Comparative Example 5 were distributed near zero potential, with an average value of -1.76 mV. Compared with Comparative Example 5, the surface potential in the aqueous dispersion system of Example 1 is significantly different.

[0143] Example 1 involved crosslinking polyaluminum chloride at pH 4.8, and the final product exhibited a high positive potential in an aqueous dispersion. This result indicates that the material surface can retain a strong positive charge under weakly acidic crosslinking conditions. This positive charge is beneficial for enhancing the interfacial adsorption of negatively charged colloidal particles, suspended particles, and extracellular polymers from microorganisms.

[0144] Comparative Example 5 was treated with polyaluminum chloride at pH 7.0, and the zeta potential of the final product was close to zero. This result indicates that the material prepared under neutral conditions has weak surface positive charge, and its electrostatic adsorption of negatively charged substances is lower than that of Example 1.

[0145] The above test results indicate that the pH conditions during the crosslinking stage of polyaluminum chloride affect the surface potential of the finished material. Controlling the crosslinking system at pH 4.8 is beneficial for obtaining modified powders with higher positive potentials, thus providing an interfacial basis for the material's colloidal adsorption, bioattachment, and floc binding in wastewater treatment processes.

[0146] Test Example 4:

[0147] Test objective: To investigate the total phosphorus removal performance of water treatment additives prepared under different conditions in simulated high-phosphorus wastewater.

[0148] The testing steps are as follows:

[0149] 1. The water treatment additive products prepared in Examples 1 to 4 and Comparative Examples 1 to 4 were used as test subjects.

[0150] 2. Simulated high-phosphorus wastewater was prepared using analytical grade potassium dihydrogen phosphate and deionized water. The initial total phosphorus concentration of the simulated high-phosphorus wastewater was measured to be 52.4 mg / L. The pH value of the simulated high-phosphorus wastewater was adjusted to approximately 7.0 using dilute hydrochloric acid or sodium hydroxide solution.

[0151] 3. Measure 500 mL of simulated high-phosphorus wastewater and add it to a 1000 mL beaker. Start the six-unit synchronous mixer and set the speed to 200 r / min. Add the corresponding group of water treatment additive product to each beaker at a dosage of 0.8 g, corresponding to a concentration of 1.6 g / L.

[0152] 4. Stir the reaction at 200 r / min for 120 min, then stop stirring and let it stand for 30 min to settle.

[0153] 5. Take a sample of the supernatant 2 cm below the liquid surface, do not filter it, and directly add potassium persulfate for high-temperature digestion. After digestion, measure the absorbance at 700 nm using ammonium molybdate spectrophotometry to calculate the residual total phosphorus concentration in the supernatant, and calculate the total phosphorus removal rate using the following formula:

[0154] Total phosphorus removal rate = (initial total phosphorus concentration - total phosphorus concentration in supernatant after reaction) / initial total phosphorus concentration × 100%.

[0155] The test data is shown in Table 4.

[0156] Table 4: Test Results of Total Phosphorus Removal Rate in Simulated Wastewater from Examples and Comparative Samples

[0157] Test sample group Initial total phosphorus concentration (mg / L) Total phosphorus concentration in the supernatant after reaction (mg / L) Total phosphorus removal rate (%) Example 1 52.4 2.65 94.94 Example 2 52.4 3.82 92.71 Example 3 52.4 2.13 95.94 Example 4 52.4 3.08 94.12 Comparative Example 1 52.4 41.76 20.31 Comparative Example 2 52.4 43.15 17.65 Comparative Example 3 52.4 44.83 14.45 Comparative Example 4 52.4 43.91 16.20

[0158] As shown in Table 4, the total phosphorus removal rates of Examples 1 to 4 were 92.71% to 95.94%, and the total phosphorus concentration in the supernatant after the reaction was 2.13 mg / L to 3.82 mg / L. The total phosphorus removal rates of Comparative Examples 1 to 4 were 14.45% to 20.31%, and the total phosphorus concentration in the supernatant after the reaction was 41.76 mg / L to 44.83 mg / L. Compared with Comparative Examples 1 to 4, Examples 1 to 4 showed higher removal levels of total phosphorus from simulated high-phosphorus wastewater.

[0159] Comparative Example 1 did not include sodium bicarbonate, Comparative Example 2 did not undergo high-temperature calcination, Comparative Example 3 did not undergo sodium gluconate pretreatment, and Comparative Example 4 changed the order of addition of sodium gluconate and polyaluminum chloride. The above comparison results show that the calcination treatment involving sodium bicarbonate, the high-temperature calcination process, the sodium gluconate pretreatment, and the order of addition all affect the total phosphorus removal performance of the finished material.

[0160] Examples 1 to 4 employed high-temperature calcination and subsequent surface modification treatments, resulting in finished products that exhibited high total phosphorus removal rates under the same dosage and reaction conditions. This result is consistent with the technical effectiveness of the material's calcium-containing silicon-based active structure, aluminum-containing modified components, and porous structure all contributing to phosphate removal. The calcium-containing and aluminum-containing components provide reaction sites for the adsorption, complexation, and precipitation removal of phosphates, while the porous structure provides interfacial conditions for the migration and contact of phosphates from water to the material surface.

[0161] Test results show that the water treatment additive prepared in this embodiment can reduce the total phosphorus concentration in simulated high-phosphorus wastewater under independent dosing conditions, and its total phosphorus removal effect is significantly better than that of the comparative samples.

[0162] Test Example 5:

[0163] Test objective: To investigate the effect of material surface modification structure on microbial adhesion and biochemical system startup process, and to evaluate the bioadhesion performance of the material as a biochemical carrier.

[0164] The testing steps are as follows:

[0165] 1. Nine simulated activated sludge bioreactors with an effective volume of 5L were constructed, divided into Example 1 group, Comparative Example 5 group and Comparative Example 6 group. Each group was equipped with three parallel reactors. Each reactor was equipped with the same aeration device and control system, and the influent conditions, aeration conditions, sedimentation time and operation cycle were kept consistent.

[0166] 2. Collect the final products obtained from Examples 1, 5 and 6, and add them to the three parallel reactors of the corresponding groups at a dosage ratio of 2 g / L, respectively, as water treatment suspension carriers.

[0167] 3. Take fresh returned sludge from the secondary sedimentation tank of the municipal wastewater treatment plant, wash and settle it with deionized water, and then inoculate it into each reactor in equal amounts. The initial sludge concentration of the system is controlled at about 2500 mg / L.

[0168] 4. Prepare simulated domestic sewage using glucose, ammonium chloride, and trace elements. Feed the sewage into each reactor and discharge it according to the same operating cycle, maintaining the dissolved oxygen concentration in each reactor between 2.0 mg / L and 3.0 mg / L, and start the reactor for biochemical treatment.

[0169] 5. At the same reaction time points on the 3rd, 7th and 14th days of system operation, 100 mL of gas-water mixture was taken out respectively. The carrier particles were retained by sieving or sedimentation separation method that matched the particle size of the carrier. The retained material was treated in an ice-water bath using an ultrasonic cell disruptor to remove the attached biofilm.

[0170] 6. The total amount of volatile suspended solids in the ultrasonic stripping fluid was determined by standard gravimetric method. Combined with the dry weight of the carrier, the bio-attachment per unit mass of the test sample at each time point was calculated.

[0171] 7. Collect influent and effluent samples from each reactor daily to determine the chemical oxygen demand (COD). When the COD removal rate of a certain reactor group is consistently above 85% for three consecutive days, record the number of days it took for that group to reach stable operation. Separately, set up an adsorption blank test with no sludge inoculation and only the corresponding material added to evaluate and deduct the impact of the material's own adsorption on the COD removal rate.

[0172] The test data is shown in Table 5.

[0173] Table 5: Test Results of Carrier Bioattachment Amount and Time to Stable Operation of the Examples and Comparative Examples

[0174] Test sample group Bioattachment amount on day 3 of operation (mg-VSS / g-carrier) Bioattachment amount on day 7 of operation (mg-VSS / g-carrier) Bioattachment level on day 14 of operation (mg-VSS / g-carrier) Number of operating days (d) to achieve a stable COD removal rate Example 1 43.6±2.4 127.4±5.1 216.5±8.3 8 Comparative Example 5 5.2±1.1 18.7±2.3 39.2±3.5 22 Comparative Example 6 21.3±1.8 54.8±3.6 82.1±4.2 17

[0175] Note: The bioattachment data at each time point in the table are the average ± standard deviation of independent samples from three parallel reactors (n=3).

[0176] As shown in Table 5, the bioattachment per unit mass of Examples 1, 5, and 6 increased with the extension of operation time on days 3, 7, and 14, but the growth rate varied significantly among different groups. The bioattachment in Example 1 was higher than that in Comparative Examples 5 and 6 at all time points, reaching 216.5 ± 8.3 mg-VSS / g-carrier on day 14. The bioattachment in Comparative Example 5 was at a lower level at all time points, while that in Comparative Example 6 was between that of Examples 1 and 5.

[0177] Regarding the time to achieve a stable COD removal rate, Example 1 took 8 days, Comparative Example 6 took 17 days, and Comparative Example 5 took 22 days. These results indicate that the material corresponding to Example 1 exhibits a better overall effect in promoting microbial attachment and shortening the system start-up period.

[0178] The difference between Comparative Example 5 and Example 1 lies in the pH adjustment conditions during the liquid phase treatment stage. Table 5 shows that Comparative Example 5 had a lower carrier bioattachment amount and a longer time to reach a stable COD removal rate. This result is consistent with the surface potential test results in Test Example 3, indicating a correlation between the surface electrical state of the material and the initial microbial attachment behavior.

[0179] Compared to Example 1, Comparative Example 6 omitted the silane coupling agent grafting step. Table 5 shows that the bioattachment amount and system start-up speed of Comparative Example 6 at each time point were lower than those of Example 1. This result reflects that the surface grafting structure has a positive effect on the stable binding of aluminum-containing modified components on the carrier surface and on the continuous attachment of microorganisms.

[0180] Example 1 exhibited high bioattachment levels and a short start-up time during operation, indicating that the combined effect of the porous framework, surface grafting structure, and aluminum-modified components is beneficial to improving the interfacial properties of the carrier surface and facilitating the enrichment and growth of microorganisms on the carrier surface. Test results show that the material prepared in Example 1, when used as a biochemical carrier, has good bioattachment performance and helps shorten the operating time for the biochemical system to reach a stable COD removal rate.

[0181] Test Example 6:

[0182] Test objective: To investigate the impact of material addition on the static settling performance of the biochemical system and to evaluate its effect on mitigating sludge bulking risk.

[0183] The testing steps are as follows:

[0184] 1. Set up two sets of sequencing batch reactors with the same effective volume and internal structure, and inoculate them with equal amounts of normal activated sludge taken from the municipal wastewater treatment plant.

[0185] 2. Add 2.0 g / L of the multifunctional water treatment additive prepared in Example 1 to one group of reactors, which is called Example 1 group; the other group of reactors does not add any carrier, which is called blank control group.

[0186] 3. Simulate domestic sewage and operate continuously for 30 days at a conventional volumetric load according to the set operating cycle. After the effluent indicators of the two systems stabilize, adjust the influent mix ratio and operating parameters, increase the influent chemical oxygen demand to 1.5 times the original level, and reduce the aeration rate to maintain the dissolved oxygen concentration in the reactor between 0.5 mg / L and 1.0 mg / L, so as to form a high-load, low-dissolved oxygen operating condition.

[0187] 4. After 14 days of continuous operation under the above-mentioned high load and low dissolved oxygen conditions, equal amounts of mixed liquor samples were collected from the fully mixed zones of the two reactors. The suspended solids concentration of the mixed liquor was determined by gravimetric method. At the same time, the volatile suspended solids concentration and the fixed suspended solids concentration of the mixed liquor were also determined to distinguish the contributions of biological sludge and inorganic carriers to the suspended solids concentration.

[0188] 5. Pour the collected mixture into 1000mL standard graduated cylinders, let it stand for 30min to settle, read and record the volume of the sediment layer, and obtain the 30min sedimentation volume SV30.

[0189] 6. Based on the mixed liquor suspended solids concentration and SV30 measurement results, calculate the apparent composite system settling index for each group of mixed liquors. For Example 1 group with added materials, the apparent composite system settling index includes the contribution of inorganic carriers to the suspended solids concentration and is not directly equivalent to the traditional activated sludge volume index.

[0190] 7. Take samples of the mixed liquor from each reactor group and place them on a glass slide. Observe the sludge floc structure, filamentous bacteria extension state, and carrier-sludge bonding morphology under an optical microscope. Record the compactness of the sludge flocs and the extension of the filamentous bacteria in each group. The microscopic observation results are shown in [Figure number missing]. Figure 3 .

[0191] The test data is shown in Table 6.

[0192] Table 6: Results of Static Sedimentation Performance Test of the Composite Biochemical System of Example 1 Group and Blank Control Group

[0193] Blank control group 2786.3 718 257.7 Example 1 Group 4251.6 324 76.2

[0194] As shown in Table 6, under the same high load and low dissolved oxygen operating conditions, the SV30 of the blank control group was 718 mL / L, and the apparent sedimentation index of the composite system was 257.7 mL / g; the SV30 of the Example 1 group was 324 mL / L, and the apparent sedimentation index of the composite system was 76.2 mL / g. Compared with the blank control group, the sedimentation layer volume and the apparent sedimentation index of the composite system in the Example 1 group were significantly reduced, indicating that the static sedimentation performance of the composite biochemical system was improved after adding the material prepared in Example 1.

[0195] After operating under high load and low dissolved oxygen conditions, the blank control group showed a higher SV30 and a higher apparent sedimentation index of the composite system, indicating a decline in sedimentation performance. Combined with... Figure 3 Microscopic observations showed that the sludge flocs in the blank control group were relatively loose, and the filamentous bacteria extended more outwards from the flocs, indicating that the system had a tendency for filamentous sludge bulking under these operating conditions.

[0196] In Example 1, under the same conditions, the SV30 decreased to 324 mL / L, and the settling layer volume decreased significantly. Microscopic observation showed that the composite sludge particles in Example 1 were relatively dense, the floc structure was relatively concentrated, and the extension of filamentous bacteria to the outside of the floc was reduced. These results indicate that the material prepared in Example 1 can improve the sludge-water separation performance of the composite biological system and help reduce the risk of sludge bulking under high load and low dissolved oxygen conditions.

[0197] The material prepared in Example 1, with industrial microsilica powder and high-temperature calcination products as its framework, can serve as an inorganic support core for the growth of sludge flocs after being added to a biochemical system. The aluminum-containing modified components and inorganic framework structure on the surface of the material help promote the bonding between sludge flocs and carrier particles, forming a composite floc structure with good settling performance, thereby improving the static settling performance of the system.

[0198] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A multifunctional water treatment additive, characterized in that, It is prepared from raw materials comprising the following parts by weight: 100 parts of primary powder; 1.0 to 3.0 parts of 3-aminopropyltriethoxysilane, based on the active ingredient; Sodium gluconate 0.5 to 1.2 parts; Polyaluminum chloride 2.0 to 4.0 parts, based on the mass of alumina; The primary powder is prepared by mixing 100 parts by weight of industrial microsilica powder, 10 to 20 parts by weight of calcium carbonate and 3 to 8 parts by weight of sodium bicarbonate, and then calcining at a high temperature of 750°C to 800°C. The primary powder is dispersed in water to form a suspension slurry. 3-aminopropyltriethoxysilane, which has undergone pre-hydrolysis treatment, is added dropwise to the suspension slurry for a grafting reaction. Sodium gluconate is then added for a pretreatment reaction. Polyaluminum chloride is then added dropwise, and the pH of the reaction system is controlled at 4.5-5.0 for a modification reaction. After the reaction, the mixture is subjected to solid-liquid separation, washing, drying, pulverizing, and sieving to obtain the multifunctional water treatment additive.

2. The multifunctional water treatment additive according to claim 1, characterized in that, The industrial microsilica powder contains ≥85 wt% amorphous silica, has a D50 of 10 μm to 50 μm, and a specific surface area ≥15 m². 2 / g; the basicity of the polyaluminum chloride is 60% to 85%.

3. The multifunctional water treatment additive according to claim 1, characterized in that, It is prepared from raw materials comprising the following parts by weight: 100 parts of primary powder; 2.0 to 2.5 parts of 3-aminopropyltriethoxysilane, based on the active ingredient; Sodium gluconate 0.8 to 1.0 parts; 3.0 to 3.5 parts of polyaluminum chloride, based on the mass of alumina; The primary powder is prepared by mixing 100 parts by weight of industrial microsilica powder, 15 to 18 parts by weight of calcium carbonate and 5 to 6 parts by weight of sodium bicarbonate, and then calcining at a high temperature of 750°C to 800°C.

4. A method for preparing a multifunctional water treatment additive as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Weigh industrial microsilica powder, calcium carbonate and sodium bicarbonate according to the weight ratio, put them into a mixer and mix evenly. Then, send them into a rotary kiln for high-temperature calcination. The material is naturally cooled to room temperature with the kiln to obtain primary powder. S2. The primary powder obtained in step S1 is added to deionized water and dispersed to prepare a suspension slurry. 3-aminopropyltriethoxysilane that has been pre-hydrolyzed is slowly added dropwise and a constant-temperature stirring grafting reaction is carried out. S3. Keeping the temperature and stirring state of the reaction system in step S2 unchanged, add sodium gluconate in solid form to the reaction system for isothermal pretreatment reaction. S4. Keeping the temperature of the reaction system in step S3 constant, add liquid polyaluminum chloride dropwise to the reaction system for isothermal modification reaction. At the same time, use acidic or alkaline aqueous solution to slowly add and adjust the pH value of the reaction system to control it between 4.5 and 5.

0. S5. The liquid material after the reaction in step S4 is subjected to solid-liquid separation. The collected filter cake is washed and then sent to a dryer to dry. After being crushed and sieved, the multifunctional water treatment additive is obtained.

5. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S1, the specific process of high-temperature roasting is as follows: the temperature is increased to 750℃~800℃ at a heating rate of 5℃ / min~10℃ / min, and then kept at 750℃~800℃ for 1.5h~2.5h.

6. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S2, the solid content of the suspension slurry is controlled at 10wt% to 20wt%; before the drop addition, the pre-hydrolysis treatment is carried out by mixing 3-aminopropyltriethoxysilane with deionized water and hydrolyzing for 15min to 30min; the temperature of the constant temperature stirring grafting reaction is controlled at 60℃ to 70℃, and the reaction time is 1h to 1.5h.

7. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S3, the temperature of the isothermal pretreatment reaction is controlled at 60℃~70℃, and the reaction time is 30min~60min.

8. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S4, pH online monitoring is activated while polyaluminum chloride is being added dropwise; the temperature of the isothermal modification reaction is controlled at 60℃~70℃, and the reaction time is 1.5h~2.5h.

9. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S4, the acidic aqueous solution is a hydrochloric acid aqueous solution with a mass fraction of 5wt% to 10wt%; the alkaline aqueous solution is a sodium hydroxide aqueous solution with a mass fraction of 5wt% to 10wt%.

10. The preparation method of the multifunctional water treatment additive according to claim 4, characterized in that, In step S5, the drying temperature is 105℃~110℃, and the material is dried until the residual moisture content is ≤5wt%.

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