Clarification and separation system with in-situ algal inhibition function and preparation method of clarification and separation system

Abstract

The invention discloses a clarification and separation system with an in-situ algal inhibition function and a preparation method thereof, and relates to the field of sewage treatment. The system comprises a clarification separator body and an effluent weir tank, and key parts of the whole surface of the inner side of the effluent weir tank, a water level fluctuation area of the inner wall of the body and the like, which are easy to breed algae, are cured and coated with a photocatalytic algal inhibition coating. The coating is formed by compounding sludge biochar and nano titanium dioxide, and an in-situ algae inhibition defense line is constructed on the surface of equipment by utilizing natural light through the synergistic effect of adsorption capture of the biochar and oxidative degradation of a photocatalyst. The invention further discloses a preparation technology comprising the steps of raw material alternating direction ball milling, base material roughening pretreatment and separated spraying and curing. The system effectively solves the problems that an overflow port of traditional equipment is prone to being blocked, and the coating on the wall of the pool is difficult to clean, the manual maintenance cost and the safety risk are remarkably reduced, chemical agents do not need to be added, and organic combination of sludge recycling and equipment self-cleaning is achieved.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a clarification and separation system with in-situ algae suppression function and its preparation method. Background Technology

[0002] In modern wastewater treatment processes, the clarification and separation system (or clarifier) ​​serves as a core component replacing the traditional secondary sedimentation tank, undertaking the crucial function of separating the three phases of gas, sludge, and water at the end of the biological treatment tank. Its operational stability directly affects the compliance of the effluent quality standards.

[0003] However, during the long-term operation of existing clarification and separation systems, local areas of the equipment are highly susceptible to algae growth due to factors such as eutrophication of wastewater (high nitrogen and phosphorus content), natural sunlight, and suitable temperature and humidity. This is especially true at the sidewalls and bottom of the effluent weir, the junction of the water level and the tank wall (the alternating wet and dry zone), and the inner side of the sedimentation module / guide plate, where algae often proliferate in large quantities.

[0004] The growth of these algae can lead to a series of serious problems: Deterioration of water quality sensory characteristics: Shed algae are discharged with the outflowing water, resulting in decreased water transparency and a deterioration in apparent sensory quality.

[0005] Equipment performance degradation: The biofilm formed by the decaying algae will adhere to the equipment surface, increasing water flow resistance and affecting the flow stability and solid-liquid separation efficiency; in addition, the decaying algae may also release odors and additional organic pollutants.

[0006] Currently, the industry mainly relies on the following traditional methods to solve the above problems, but all of them have obvious shortcomings: Manual, periodic cleaning: This is the most common method, but it is extremely labor-intensive and involves a harsh working environment (odors, slippery surfaces). Maintenance is typically performed 1-2 times per month and often involves working at heights or in confined spaces, posing significant safety risks and substantially increasing the operating costs of wastewater treatment plants.

[0007] Adding chemical algaecides: While effective quickly, this method carries the risk of secondary pollution and can easily disrupt the microecological balance of the water body. Furthermore, the agents are difficult to apply precisely to specific areas of algae growth, resulting in poor sustainability of the algae-suppressing effect, and require continuous chemical input, leading to high costs.

[0008] In recent years, photocatalysis technology (such as using titanium dioxide TiO2) has attracted attention in the field of water treatment due to its environmentally friendly characteristics. However, the direct application of traditional photocatalytic materials to clarification and separation systems still faces technical bottlenecks: Limited catalytic efficiency: Ordinary nano-TiO2 has limited responsiveness under visible light and a high recombination rate of photogenerated electron-hole pairs, resulting in unsatisfactory actual algae suppression efficiency.

[0009] Lack of adsorption capacity: If suspended algae are not effectively "captured" on the catalyst surface, active free radicals will have difficulty killing them effectively, lacking the synergistic effect of "adsorption-catalysis".

[0010] Poor coating durability: Ordinary coatings are prone to peeling off under wastewater flushing conditions. Developing a photocatalytic coating that possesses both strong adhesion and maintains porous adsorption activity is currently a technological challenge.

[0011] Furthermore, the disposal of residual sludge generated during wastewater treatment is also a major challenge in the industry. How to transform sludge into a valuable resource and develop new functional materials and supporting equipment that can simultaneously address both algae growth and sludge resource utilization are urgent technical problems that need to be solved in this field. Summary of the Invention

[0012] (a) Technical problems to be solved The present invention aims to solve the technical problem that, during long-term operation, existing sewage treatment clarification and separation equipment is prone to algae growth in key areas such as the inner side of the effluent weir and the alternating wet and dry zone of the water level, which leads to a decline in the sensory quality of the effluent and affects the separation efficiency and flow stability of the equipment.

[0013] Meanwhile, in view of the shortcomings of existing technologies, such as the high labor intensity and safety risks of manual cleaning, the easy secondary pollution caused by adding chemical algaecides and the difficulty in accurately targeting the growth surface, and the poor adhesion of traditional photocatalytic materials in sewage flushing environment and the high recombination rate of photogenerated electrons and holes leading to low actual algae suppression efficiency, this invention provides a clarification and separation system and its preparation method that utilizes sludge biochar for enhancement and performs functional coating on specific susceptible areas.

[0014] (II) Technical Solution To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a clarification and separation system with in-situ algae suppression function.

[0015] The system includes a clarifier body, an outlet weir located on the side of the clarifier body, and an outlet communicating with the outlet weir. Its key feature is that the clarifier system has a photocatalytic algae-inhibiting coating solidified and coated on key surfaces prone to algae growth. These key surfaces include at least the entire inner surface of the outlet weir and the water level fluctuation area on the inner wall of the clarifier body. The photocatalytic algae-inhibiting coating utilizes strong oxidizing free radicals generated by natural or ambient light to inhibit algae growth in situ on the contacting water, maintaining the cleanliness of the outlet weir and the water level fluctuation area from the source, thus preventing algae attachment and growth.

[0016] As a preferred technical solution, the components of the photocatalytic algae-inhibiting coating have been specifically designed: The coating consists of a composite photocatalyst, a dispersant, and a binder. The composite photocatalyst is a mixture of sludge biochar and nano-titanium dioxide (TiO2) in a mass ratio of 1:1 to 1:2. The sludge biochar has a rich porous structure, which is used to adsorb and enrich algal spores and organic nutrients in the water, "capture" suspended pollutants to the surface of the catalyst, and form an "adsorption-photocatalysis" synergistic effect with nano-titanium dioxide to improve catalytic efficiency.

[0017] Furthermore, in order to ensure the physical properties and chemical activity of the coating: The sludge biochar is prepared by pyrolyzing sludge at 500–600℃ for 1.5–2.5 hours, with a particle size controlled at 20–38 μm. The nano-titanium dioxide is anatase type with a particle size of 10–50 nm. The dispersant is selected from sodium hexametaphosphate or sodium tripolyphosphate, and the addition amount is 0.5%–2% of the total coating mass to ensure uniform dispersion of particles in the slurry. The binder is a urethane-terminated polyester binder, and the addition amount is 1.5%–2.5% of the total coating mass to impart excellent water erosion resistance to the coating. The cured coating has a porosity ≥25%, a specific surface area ≥150 m² / g, a coating thickness of 50–200 μm, and a bonding strength with the substrate ≥3 MPa.

[0018] As a further definition of the coating area, the specific range of the water level fluctuation area is as follows: Based on the system design water level line, an annular wall area extending upwards to 30cm to 50cm and downwards to 30cm to 50cm is included. This area covers the alternating wet and dry zone caused by liquid level changes and is the area where algae grow most vigorously. If the upper edge of the outlet weir is designed as a serrated overflow outlet, the photocatalytic algae-inhibiting coating should completely cover the edge surface of the serrated overflow outlet. In addition, if the outlet weir has reinforcing ribs inside, or if the system has a flow guide plate, the photocatalytic algae-inhibiting coating should also be applied to the surface of the reinforcing ribs or the flow guide plate.

[0019] Secondly, the present invention also provides a method for preparing the above-mentioned clarification and separation system with in-situ algae suppression function, comprising the following steps: Step 1: Preparation of coating raw materials: Weigh out sludge biochar powder and nano-titanium dioxide according to the specified ratio, add dispersant, binder, and deionized water (solid-liquid mass ratio 1:0.8–1.2), and perform alternating-direction ball milling in a ball mill. The ball milling speed is controlled at 300–600 rpm, the time is 5–12 hours, and the milling direction is switched every 30 minutes. This alternating ball milling process helps to form a tight contact interface and S-shaped heterojunction structure between biochar and TiO2, ultimately producing a composite photocatalytic slurry or powder.

[0020] Step 2: Substrate Pretreatment The areas to be coated in the clarification and separation system (such as the effluent weir and the water level fluctuation zone) are treated with rust removal, degreasing, and grinding to achieve a surface roughness Ra of 3.2–6.3 μm, thereby increasing the physical and mechanical adhesion between the coating and the substrate.

[0021] Step 3: Coating and Curing Using high-pressure airless spraying equipment, the prepared slurry is evenly applied to the area to be coated in 2 to 3 coats, with a certain time interval between each coat. Finally, it is cured at 80 to 120°C for 2 to 3 hours to allow the coating to fully cross-link and cure, forming a high-strength surface with algae-inhibiting function.

[0022] Compared with the prior art, the beneficial effects of the present invention are: This invention involves solidifying a photocatalytic algae-inhibiting coating at key algae-prone areas of the clarification and separation system, such as the effluent weir and water level fluctuation zone. This utilizes natural light to create an in-situ self-cleaning surface, effectively blocking algal cell attachment and growth at the source. This targeted system design effectively solves problems caused by algae growth during long-term operation of traditional equipment, such as overflow clogging, algae buildup on tank walls, and deterioration of effluent sensory quality, ensuring the flow stability and treatment efficiency of the clarification and separation process.

[0023] This system innovatively utilizes the adsorption and enrichment effect of sludge biochar and the photocatalytic oxidation capability of nano-titanium dioxide to form a dual-effect synergistic mechanism, which significantly improves the algae suppression efficiency in flowing sewage environments. The biochar carrier can actively capture tiny algal spores and organic nutrients in the water and fix them on the catalyst surface for efficient degradation, overcoming the technical bottleneck of traditional photocatalytic materials being unable to "capture" suspended pollutants, while realizing the resource utilization of residual sludge.

[0024] In addition, the coating of this system undergoes specific enhancement modifications and surface treatments, resulting in excellent water erosion resistance and substrate bonding strength, making it suitable for the turbulent hydraulic conditions of the effluent weir. This significantly extends the maintenance-free cycle of the equipment, substantially reduces the frequency of manual high-altitude cleaning and operational safety risks, and eliminates the need for any chemical additives, thus avoiding secondary pollution. It provides wastewater treatment plants with a low-cost, long-life, and environmentally friendly green operation and maintenance solution. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a plan view of the clarifier separator and algae-inhibiting coating of the present invention; Figure 2 This is an elevation view of the clarifier separator and algae-inhibiting coating of the present invention; Figure 3 This is a plan view of the water collection weir and algae-inhibiting coating of the present invention.

[0026] Reference numerals in the attached drawings: 1. Clarifier / Separator body; 2. Water distribution device; 3. Water collection weir; 4. Water collection weir reinforcing rib; 5. Water outlet; 6. Water outlet pipe. Detailed Implementation

[0027] The technical solutions of 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0028] like Figures 1 to 3 As shown, the present invention provides a clarification and separation system with in-situ algae suppression function and its preparation method.

[0029] I. Overall Structure and Algae Suppression Zone Layout of the Clarification and Separation System refer to Figure 1 (Floor plan) and Figure 2 (Elevation view) The clarification and separation system mainly consists of the following hardware components: 1. Clarifier / Separator Body 1: Typically a box or cylindrical structure, with a conical or pyramidal bottom (e.g., Figure 2 As shown in the figure, it is used for the sedimentation and concentration of sludge for discharge.

[0030] 2. Water Inlet / Outlet Components: Water distribution devices 2 are provided on both sides of the main body 1; a water outlet weir 3 is provided at the upper end of the side, which is connected to an external pipe through a water outlet 5. To enhance mechanical strength, several reinforcing ribs 4 are provided laterally inside the water outlet weir 3. Figure 3 As shown, the upper edge of the outlet weir 3 is usually designed as a serrated (or triangular) overflow outlet to ensure uniform water load.

[0031] In-situ algae-inhibiting coating area: To address the algae growth problem at its source, this system applies a photocatalytic algae-inhibiting coating to specific "algae-susceptible areas" (marked as "coating" in the shaded or drawn areas in the diagram). In practice, the coating coverage strictly adheres to the following principles: 1. High-velocity enrichment zone (outlet weir / channel area): such as Figure 1 and Figure 3 As shown, the photocatalytic algae-inhibiting coating is uniformly applied to the entire inner surface of the effluent weir 3 (including the bottom, walls, and edge surfaces of the serrated overflow outlet) and the surface of the reinforcing ribs 4 (or, if present, the guide plate). This area, where water flow continuously brings nutrients, is a major site for algae attachment.

[0032] 2. Zones with alternating sunlight and wet / dry conditions (areas with fluctuating water levels): For example... Figure 2 As shown, an annular coating strip is provided on the inner wall of the clarifier body 1. The specific coating range is an annular wall area extending upwards to 30cm to 50cm and downwards to 30cm to 50cm from the system design water level line. This area is in an environment with strong light and alternating wet and dry conditions, which is most suitable for algae blooms and is the key line of defense for algae suppression in this invention.

[0033] II. System Preparation Process and Coating Material Examples The preparation method of this system mainly includes: modification and preparation of photocatalytic raw materials, pretreatment of system substrate, and spraying and curing of coating.

[0034] [Example 1]: Standard Algae Suppression, Clarification and Separation System 1. Preparation of coating raw materials (ball milling modification): Raw material ratio: The coating consists of a composite photocatalyst (sludge biochar: nano TiO2 mass ratio = 1:1), a dispersant (sodium tripolyphosphate, accounting for 0.8% of the total coating mass), and a binder (terminated urethane polyester, accounting for 1.8% of the total coating mass).

[0035] Material specifications: Sludge biochar is prepared by pyrolyzing municipal dewatered sludge at 600℃ for 2 hours and then grinding and screening it (particle size 20~38μm); the nano TiO2 is anatase type (particle size 30nm).

[0036] Ball milling process: Mix the above raw materials with deionized water at a solid-liquid ratio of 1:0.9 and place the mixture in a ball mill. Set the rotation speed to 350 rpm and the milling time to 10 hours. To prevent particle agglomeration and the formation of uniform S-shaped heterojunctions, switch the milling direction every 30 minutes. The slurry is then cooled, dried, and sieved before use.

[0037] 2. System substrate pretreatment: right Figure 1-3 The inner wall of the outlet weir 3 and the water level fluctuation area of ​​the main body 1 are mechanically ground, rusted, and degreased. Key control indicator: The surface roughness Ra of the surface to be coated is made to reach 3.2~6.3μm to enhance the physical anchoring points.

[0038] 3. Coating and curing: The prepared composite powder was formulated into a slurry and then uniformly coated onto the key areas in two passes using a high-pressure airless sprayer (spraying pressure 0.35 MPa). After coating, the slurry was cured at 90°C for 2 hours using a heating device.

[0039] Finished product parameters: The cured coating has a thickness of approximately 120 μm, a porosity of 28%, and a bonding strength of 3.2 MPa with the concrete / metal substrate.

[0040] [Example 2]: Enhanced Algae Suppression, Clarification, and Separation System Compared to Example 1, the main improvements were made to the formulation and process to adapt to harsher operating conditions: 1. Formula adjustment: The mass ratio of sludge biochar to nano TiO2 was adjusted to 1:2 to increase the proportion of photocatalytic active components; the dispersant was changed to sodium hexametaphosphate (2%), and the binder content was increased to 2.5% to maximize wear resistance.

[0041] 2. Process Adjustment: The ball milling speed was increased to 500 rpm, and the time was extended to 12 hours to achieve a denser bonding of components. The spraying pressure was increased to 0.5 MPa, and the coating was applied in three coats.

[0042] 3. Curing conditions: Increase the curing temperature to 120℃ and extend the curing time to 3 hours.

[0043] Finished product parameters: The coating is approximately 200 μm thick, with a bonding strength increased to 3.8 MPa. The pore structure remains intact, allowing it to withstand long-term scouring by high-speed water flow.

[0044] III. Working Principle and Field Verification When the above system is in operation, sunlight or ambient light shines on the coating surface of the outlet weir 3 and the water level area, resulting in the following synergistic effect: 1. Adsorption and enrichment: The unique porous structure of sludge biochar in the coating (specific surface area ≥150m² / g) acts like a miniature sponge, adsorbing and fixing tiny algal spores and organic nutrients in the water flow onto the coating surface.

[0045] 2. In-situ catalysis: Under light irradiation, the S-shaped heterojunction formed by nano-TiO2 and biochar undergoes electron-hole separation, generating highly oxidizing •O2. - And OH free radicals. These free radicals directly damage the cell walls and cell membranes of the adsorbed algae.

[0046] 3. Self-cleaning: The dead algal remains are further oxidized and decomposed, preventing the formation of biological slime, thus keeping the weir and pool walls clean.

[0047] Verification results: After on-site application testing at a wastewater treatment plant, the clarification and separation tank modified using the scheme of Example 1 of this invention showed no obvious green algae attachment on the inner wall of the effluent weir and the water level area after 12 months of continuous operation, and the surface still maintained its original color. Compared with the adjacent parallel group that was not modified, the algae suppression rate reached more than 90%, and there was no blockage at the effluent weir, which verified the effectiveness of the system's "specific area + specific material" combination.

[0048] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A clarification and separation system with in-situ algae suppression function, comprising a clarifier body (1), an outlet weir (3) disposed on the side of the clarifier body (1), and an outlet (5) communicating with the outlet weir (3); characterized in that: The clarification and separation system has a photocatalytic algae-inhibiting coating solidified and coated on key surfaces that are prone to algae growth; the key surfaces include at least: the entire inner surface of the effluent weir (3) and the water level fluctuation area on the inner wall of the clarifier body (1); The photocatalytic algae-inhibiting coating uses natural light or ambient light to inhibit algae in situ on the water body in contact with it, keeping the surface of the outlet weir (3) and the water level fluctuation area clean.

2. The clarification and separation system with in-situ algae suppression function according to claim 1, characterized in that, The photocatalytic algae-inhibiting coating is composed of a composite photocatalyst, a dispersant, and a binder; The composite photocatalyst is composed of sludge biochar and nano titanium dioxide (TiO2) in a mass ratio of 1:1 to 1:

2. The sludge biochar has a porous structure, which is used to adsorb and enrich algal spores and organic nutrients in water, and forms an adsorption-photocatalytic synergistic effect with nano titanium dioxide.

3. The clarification and separation system with in-situ algae suppression function according to claim 1, characterized in that, The sludge biochar is prepared by pyrolyzing sludge at 500-600℃ for 1.5-2.5 hours, and its particle size is 20-38μm; the nano titanium dioxide is anatase type, with a particle size of 10-50nm. The dispersant is selected from sodium hexametaphosphate or sodium tripolyphosphate, and the addition amount is 0.5% to 2% of the total mass of the coating; the binder is a urethane-terminated polyester binder, and the addition amount is 1.5% to 2.5% of the total mass of the coating.

4. The clarification and separation system with in-situ algae suppression function according to claim 1, characterized in that, The specific range of the water level fluctuation area is as follows: Based on the system design water level line, there is an annular wall area extending upwards to 30cm to 50cm and downwards to 30cm to 50cm. The upper edge of the outlet weir (3) is a serrated overflow port, and the photocatalytic algae-inhibiting coating completely covers the edge surface of the serrated overflow port.

5. The clarification and separation system with in-situ algae suppression function according to claim 1, characterized in that, The outlet weir (3) is provided with reinforcing ribs (4) inside, or the system is provided with a flow guide plate, and the photocatalytic algae-inhibiting coating is also applied to the surface of the reinforcing ribs (4) or the flow guide plate.

6. The clarification and separation system with in-situ algae suppression function according to any one of claims 1 to 5, characterized in that, The physical properties of the photocatalytic algae-inhibiting coating satisfy: The cured coating has a porosity of ≥25%, a specific surface area of ​​≥150m² / g, a coating thickness of 50~200μm, and a bonding strength with the substrate of ≥3MPa.

7. A method for preparing a clarification and separation system with in-situ algae-inhibiting function as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Preparation of coating raw materials: Weigh sludge biochar powder and nano titanium dioxide, add dispersant, binder and deionized water, and ball mill in alternating directions to obtain composite photocatalytic slurry or powder; Step 2, Substrate Pretreatment: The parts of the clarification and separation system to be coated are derusted, degreased, and polished to achieve a surface roughness Ra of 3.2–6.3 μm; Step 3, Coating and Curing: Using a high-pressure airless spraying device, apply the slurry evenly to the area to be coated in 2 to 3 coats, with a certain time interval between each coat. Finally, cure at a temperature of 80 to 120°C for 2 to 3 hours.

8. The preparation method according to claim 7, characterized in that, The ball milling process in step one is as follows: The solid-liquid mass ratio is 1:0.8 to 1.2, the ball milling speed is 300 to 600 rpm, the time is 5 to 12 hours, and the ball milling direction is switched every 30 minutes to form an S-shaped heterojunction structure.

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