Efficient phosphorus removal agent and preparation method thereof

Abstract

The invention discloses an efficient composite phosphorus removal agent and a preparation method thereof, and belongs to the technical field of water treatment agents. The phosphorus removal agent comprises the following active components in percentage by mass: 15-35% of an iron-based compound (in terms of Fe), 5-20% of an aluminum-based compound (in terms of Al), 2-10% of a magnesium-based compound (in terms of Mg), 0.5-5% of a silicate additive, 0.1-2% of an organic polymer coagulant aid and the balance of water, the molar ratio of Fe to Al to Mg is (1.5-3.0): 1.0: (0.2-0.8), the pH value is 1.5-3.5, and the density is 1.25-1.40 g / cm at 20 DEG C. The preparation method comprises four steps of iron and aluminum mixed reaction, magnesium salt introduction, silicate modification and blending stabilization, the reaction condition is mild, and the process is simple and controllable. The phosphorus removal agent is remarkable in phosphorus removal effect through multi-metal synergistic effect, silicate modification and coagulant aid reinforcement, the total phosphorus concentration of a water body can be reduced to 0.1 mg / L or below, the applicable pH range is expanded to 5.0-9.0, the sludge yield is reduced by 20%-30%, the phosphorus removal agent is suitable for various water quality scenes such as town sewage and industrial wastewater, the storage stability of a finished product is good, and the phosphorus removal agent has a wide application prospect.

Description

Technical Field

[0001] This invention relates to the field of water treatment agents, and in particular to a highly efficient phosphorus removal agent and its preparation method. Background Technology

[0002] Eutrophication is a major global water environment problem, with excessive phosphorus input being the primary driver of abnormal algal blooms (algal blooms or red tides) in lakes, rivers, and coastal waters. Phosphorus mainly originates from urban sewage, industrial wastewater (such as from phosphate chemical, electroplating, and fertilizer production), and agricultural non-point source pollution. To control eutrophication, countries worldwide are increasingly stringent on total phosphorus concentration limits in discharged water, with many regions requiring total phosphorus concentrations in wastewater treatment plant effluents to be below 0.3 mg / L, and even reaching the extreme standard of 0.1 mg / L. Therefore, developing technologies and materials capable of achieving deep, efficient, and economical phosphorus removal under complex water quality conditions has become an urgent need in the water treatment field.

[0003] Currently, mainstream chemical phosphorus removal technology involves adding phosphorus removal agents to convert phosphates in water into insoluble precipitates, which are then removed through solid-liquid separation. However, traditional phosphorus removal agents generally suffer from problems such as insufficient phosphorus removal efficiency and depth, narrow applicable pH range, large sludge production, potential secondary pollution, and high overall costs. Especially when dealing with actual wastewater with complex compositions and diverse phosphorus forms (orthophosphate, polyphosphate, organophosphate), single metal salt agents often struggle to consistently meet increasingly stringent emission standards. Therefore, there is an urgent need in this field for a novel, highly efficient composite phosphorus removal agent. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a highly efficient phosphorus removal agent and its preparation method.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A highly efficient composite phosphorus removal agent, whose active ingredients are composed of the following components by weight percentage: Iron-based compounds (based on Fe): 15%-35%, Aluminum-based compounds (based on Al): 5%-20%, Magnesium-based compounds (based on Mg): 2%-10%, Silicate additives: 0.5%-5%, Organic polymeric coagulant aid: 0.1%-2%, The remainder is water.

[0006] As a further aspect of the present invention, the iron-based compound is selected from one or more of ferric chloride, ferric sulfate, and polyferric sulfate; the aluminum-based compound is selected from one or more of polyaluminum chloride, aluminum sulfate, and sodium aluminate; and the magnesium-based compound is selected from one or more of magnesium chloride and magnesium sulfate.

[0007] As a further embodiment of the present invention, the silicate additive is water glass or silica sol with a modulus of 2.0-3.2; the organic polymeric coagulant is cationic polyacrylamide with a molecular weight range of 3 million to 8 million.

[0008] As a further aspect of the present invention, the molar ratio of Fe, Al, and Mg in the phosphorus removal agent is (1.5-3.0):(1.0):(0.2-0.8); the pH value of the phosphorus removal agent is 1.5-3.5, and the density (20℃) is 1.25-1.40 g / cm³.

[0009] A method for preparing the aforementioned high-efficiency composite phosphorus removal agent includes the following steps: Step 1. Mixing reaction: In the reaction vessel, first add the measured amount of water, then add the iron-based compound and aluminum-based compound in sequence under stirring, control the temperature at 40-60℃, and stir the reaction for 30-60 minutes to obtain the iron-aluminum composite mother liquor; Step 2. Introduction of magnesium salt: Prepare an aqueous solution of magnesium-based compound and slowly add it to the mother liquor obtained in Step 1. During the addition process, maintain the system temperature at 50-70℃ and continue stirring the reaction for 60-90 minutes. Step 3. Silicate modification: Slowly add the silicate additive to the reaction system in step 2. After the addition is complete, mature at 60-80℃ for 2-4 hours. Step 4. Preparation and Stabilization: Cool the reaction system to below 40°C, add the organic polymer coagulant, stir evenly, and let it stand for at least 24 hours to obtain the finished high-efficiency composite phosphorus removal agent.

[0010] As a further embodiment of the present invention, in step 3, the dropping rate of the silicate additive is controlled to allow the pH value of the system to rise slowly, and the final reaction endpoint pH value is controlled at 2.0-3.0.

[0011] As a further aspect of the present invention, the stirring speed of the entire preparation process is controlled at 100-300 rpm, and the reactions in steps 2 and 3 are carried out under normal pressure, closed or slightly negative pressure conditions.

[0012] The beneficial effects of this invention are as follows: 1. Significant synergistic phosphorus removal effect: This invention adopts a multi-metal composite system of iron, aluminum, and magnesium. Iron-based compounds can quickly react with phosphate to form stable precipitates, aluminum-based compounds can play a role in a wide pH range and enhance the adsorption effect, and magnesium-based compounds can improve the density of the precipitates. The three are combined in a specific molar ratio, which solves the problem of incomplete phosphorus removal by single metal salt agents. It can reduce the total phosphorus concentration in water to below 0.1 mg / L, meeting strict discharge standards.

[0013] 2. Wide range of applications: Through the modification effect of silicate additives, the pH range of the phosphorus removal agent is extended to 5.0-9.0, eliminating the need for frequent adjustment of wastewater pH value. It is suitable for various water quality scenarios such as urban sewage and industrial wastewater, reducing the complexity of operation.

[0014] 3. Low sludge production and good stability: The addition of organic polymer coagulant promotes floc settling, reducing sludge production by 20%-30% compared to traditional phosphorus removal agents. The precipitate has low water content and strong stability, reducing sludge disposal costs and the risk of secondary pollution.

[0015] 4. Simple and controllable preparation process: The stepwise reaction and ripening process is adopted, the reaction conditions are mild, no high temperature and high pressure equipment is required, the production process is easy to scale up, and the finished product has good storage stability. The performance does not significantly decrease after 6 months of sealed storage at room temperature. Attached Figure Description

[0016] Figure 1 This is a flow chart of the preparation process of a high-efficiency phosphorus removal agent and its preparation method proposed in this invention. Detailed Implementation

[0017] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Reference Figure 1 , Example

[0020] A highly efficient composite phosphorus removal agent comprises the following components by mass percentage: 15% polyferric sulfate (calculated as Fe), 10% polyaluminum chloride (calculated as Al), 5% magnesium chloride (calculated as Mg), 2% water glass with a modulus of 2.5, 0.5% cationic polyacrylamide (molecular weight 5 million), and the balance being water. The molar ratio of Fe, Al, and Mg is 2.0:1.0:0.5. The finished product has a pH of 2.5 and a density of 1.30 g / cm³ at 20°C.

[0021] Preparation method: Step 1. Mixing reaction: Add 575 mL of deionized water to a 1000 mL reaction vessel, turn on the stirrer (200 rpm), add polyferric sulfate containing 15 g Fe and polyaluminum chloride containing 10 g Al in sequence, heat to 50 °C, stir and react for 45 minutes to obtain iron-aluminum composite mother liquor; Step 2. Introduction of magnesium salt: Dissolve magnesium chloride containing 5g Mg in 50mL of deionized water, and slowly add it dropwise to the above mother liquor. The addition time is controlled at 15 minutes. Maintain the system temperature at 60℃ and continue stirring for 75 minutes. Step 3. Silicate modification: Slowly add 20g of water glass with a modulus of 2.5 to the reaction system, controlling the dropping rate to make the pH value rise slowly, with the final pH value being 2.5. After the dropping is completed, heat to 70℃ and mature for 3 hours. Step 4. Preparation and Stabilization: Cool the system to 35°C, add 5g of cationic polyacrylamide, stir for 30 minutes until homogeneous, and let stand for 24 hours to mature, and obtain the finished product.

[0022] Application test: 1000 mL of simulated industrial wastewater was taken, and 50 mg / L of the above-mentioned phosphorus removal agent was added. The mixture was stirred rapidly for 1 minute (300 rpm), then slowly for 10 minutes (50 rpm), and allowed to stand for 30 minutes before testing. The results showed that the total phosphorus removal rate was 99.2%, the total phosphorus concentration in the effluent was 0.08 mg / L, the sludge production was 120 mg / L, and the turbidity removal rate was 92%. Example

[0023] A highly efficient composite phosphorus removal agent comprises the following components by mass percentage: 35% ferric chloride (calculated as Fe), 5% aluminum sulfate (calculated as Al), 2% magnesium sulfate (calculated as Mg), 0.5% silica sol with a modulus of 3.2, 0.1% cationic polyacrylamide (molecular weight 8 million), and the balance being water. The molar ratio of Fe, Al, and Mg is 3.0:1.0:0.2. The finished product has a pH of 1.5 and a density of 1.40 g / cm³ at 20°C.

[0024] Preparation method: Step 1. Mixing reaction: Add 572.4 mL of deionized water to a 1000 mL reaction vessel, stir at 100 rpm, add ferric chloride containing 35 g Fe and aluminum sulfate containing 5 g Al in sequence, heat to 60 °C, stir and react for 30 minutes to obtain iron-aluminum composite mother liquor; Step 2. Magnesium salt introduction: Dissolve magnesium sulfate containing 2g Mg in 30mL of deionized water, slowly add it to the mother liquor, maintain the temperature at 70℃, and stir the reaction for 60 minutes; Step 3. Silicate modification: Slowly add 5g of silica sol with a modulus of 3.2, control the final pH value to 2.0, and after the addition is complete, heat to 80℃ and mature for 2 hours; Step 4. Preparation and Stabilization: Cool to 30℃, add 1g of cationic polyacrylamide, stir evenly, and let stand for 36 hours to obtain the finished product.

[0025] Application test: 1000 mL of actual urban sewage was taken, and 80 mg / L of phosphorus removal agent was added. The treatment was carried out under the stirring and settling conditions of Example 1. The results showed that the total phosphorus removal rate was 98.8%, the total phosphorus concentration in the effluent was 0.042 mg / L, the sludge production was 95 mg / L, and the turbidity removal rate was 90%. Example

[0026] A highly efficient composite phosphorus removal agent comprises the following components by mass percentage: 25% ferric sulfate (Fe), 20% sodium aluminate (Al), 10% magnesium chloride (Mg), 5% water glass with a modulus of 2.0, 2% cationic polyacrylamide (molecular weight 3 million), and the balance being water. The molar ratio of Fe, Al, and Mg is 1.5:1.0:0.8. The finished product has a pH of 3.5 and a density of 1.25 g / cm³ at 20°C.

[0027] Preparation method: Step 1. Mixing reaction: Add 380mL of deionized water to a 1000mL reactor, stir at 300 rpm, add ferric sulfate containing 25gFe and sodium aluminate containing 20gAl in sequence, heat to 40℃, stir and react for 60 minutes to obtain iron-aluminum composite mother liquor; Step 2. Magnesium salt introduction: Dissolve magnesium chloride containing 10g Mg in 100mL of deionized water, slowly add it to the mother liquor, maintain the temperature at 50℃, and stir the reaction for 90 minutes. Step 3. Silicate modification: Slowly add 50g of water glass with a modulus of 2.0, controlling the final pH value to be 3.0. After the addition is complete, heat to 60℃ and mature for 4 hours. Step 4. Preparation and Stabilization: Cool to 25°C, add 20g of cationic polyacrylamide, stir evenly, and let stand for 48 hours to mature, and obtain the finished product.

[0028] Application test: 1000 mL of acidic simulated wastewater (total phosphorus 15 mg / L) with a pH of 5.0 was taken and treated with 100 mg / L of phosphorus removal agent. The results showed that the total phosphorus removal rate was 99.0%, the total phosphorus in the effluent was 0.15 mg / L, and the sludge production was 150 mg / L. The ideal effect was achieved without adjusting the pH.

[0029] Working Principle: The phosphorus removal mechanism of this invention's high-efficiency phosphorus removal agent mainly includes the following synergistic effects: 1. Complexation and precipitation: Iron, aluminum, and magnesium ions hydrolyze in water to generate polynuclear hydroxy complexes, which form stable insoluble salt precipitates (such as FePO4, AlPO4, etc.) with phosphate ions; 2. Adsorption: Metal hydroxide flocs have a large specific surface area and positive charge, which can capture phosphate and organic phosphorus molecules in water through electrostatic adsorption; 3. Netting and sweeping: The gel-like substance formed by silicate additives works together with organic polymer coagulants to construct a three-dimensional network structure, which nets and promotes the sedimentation of fine phosphorus precipitates; 4. Stabilization: Magnesium ions and silicates can improve the crystallinity and density of precipitates, reduce sludge moisture content, and inhibit the back dissolution of precipitates, ensuring that the phosphorus concentration in the effluent remains stable and meets the standards for a long time.

[0030] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0031] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-efficiency composite phosphorus removal agent, characterized in that, Its active ingredients, by weight percentage, consist of the following components: Iron-based compounds (based on Fe): 15%-35%, Aluminum-based compounds (based on Al): 5%-20%, Magnesium-based compounds (based on Mg): 2%-10%, Silicate additives: 0.5%-5%, Organic polymeric coagulant aid: 0.1%-2%, The remainder is water.

2. The high-efficiency composite phosphorus removal agent according to claim 1, characterized in that, The iron-based compound is selected from one or more of ferric chloride, ferric sulfate, and polyferric sulfate; the aluminum-based compound is selected from one or more of polyaluminum chloride, aluminum sulfate, and sodium aluminate; and the magnesium-based compound is selected from one or more of magnesium chloride and magnesium sulfate.

3. The high-efficiency composite phosphorus removal agent according to claim 1, characterized in that, The silicate additive is water glass or silica sol with a modulus of 2.0-3.2; the organic polymeric coagulant is cationic polyacrylamide with a molecular weight range of 3 million to 8 million.

4. The high-efficiency composite phosphorus removal agent according to claim 1, characterized in that, The molar ratio of Fe, Al, and Mg in the phosphorus removal agent is (1.5-3.0):(1.0):(0.2-0.8); the pH value of the phosphorus removal agent is 1.5-3.5, and the density (20℃) is 1.25-1.40 g / cm³.

5. A method for preparing the high-efficiency composite phosphorus removal agent as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1. Mixing reaction: In the reaction vessel, first add the measured amount of water, then add the iron-based compound and aluminum-based compound in sequence under stirring, control the temperature at 40-60℃, and stir the reaction for 30-60 minutes to obtain the iron-aluminum composite mother liquor; Step 2. Introduction of magnesium salt: Prepare an aqueous solution of magnesium-based compound and slowly add it to the mother liquor obtained in step (1). During the addition process, maintain the system temperature at 50-70℃ and continue stirring for 60-90 minutes. Step 3. Silicate modification: Slowly add the silicate additive to the reaction system in step 2. After the addition is complete, mature at 60-80℃ for 2-4 hours. Step 4. Preparation and Stabilization: Cool the reaction system to below 40°C, add the organic polymer coagulant, stir evenly, and let it stand for at least 24 hours to obtain the finished high-efficiency composite phosphorus removal agent.

6. The preparation method according to claim 5, characterized in that, In step 3, the dropping rate of the silicate additive is controlled to allow the pH value of the system to rise slowly, and the final reaction endpoint pH value is controlled at 2.0-3.

0.

7. The preparation method according to claim 5, characterized in that, The stirring speed throughout the preparation process was controlled at 100-300 rpm, and the reactions in steps 2 and 3 were carried out under normal pressure, closed or slightly negative pressure conditions.

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