A method for constructing a biofilm carrier based on aquatic plant straw

Abstract

This invention discloses a method for constructing a biofilm carrier based on aquatic plant straw, comprising: preparing a functional bacterial agent; pretreating the aquatic plant straw; preparing a polymer substrate; diluting the functional bacterial agent into a functional bacterial agent soaking solution; soaking the pretreated aquatic plant straw in the functional bacterial agent soaking solution; removing the soaked aquatic plant straw, weaving it into multiple layers of regular polygons, and placing it on the polymer substrate. The biofilm carrier of this invention combines the chemical properties and physical strength of the functional bacterial agent and aquatic plant straw. The composite functional bacterial agent can effectively remove nitrogen and organic pollutants from polluted water bodies through processes such as ammonia oxidation, nitrification, and denitrification. Aquatic plant straw, as a high-quality carrier, can play multiple roles in wastewater treatment.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically including a method for constructing and applying a biofilm carrier based on aquatic plant straw. Background Technology

[0002] Using biofilm-based deep purification of slightly polluted water bodies or wastewater treatment plant effluent is a common method, and plant straw can serve as a high-quality biofilm carrier material. For example, application number 201810492973X, entitled "A Wastewater Treatment Biofilm Carrier Device Based on Soybean Straw and Its Usage Method," illustrates this. However, different types of plant straw typically possess different physical and chemical properties, resulting in varying effects as biofilm carriers and microbial carbon sources. Furthermore, a suitable carrier can not only utilize its biological and chemical characteristics to provide a good attachment site for microorganisms but also perform other functions, such as providing a carbon source and structural support. Summary of the Invention

[0003] The purpose of this invention is to construct a biofilm carrier based on aquatic plant straw.

[0004] The technical solution of the present invention is as follows:

[0005] A method for constructing a biofilm carrier based on aquatic plant straw includes the following steps:

[0006] Step 1: Prepare functional microbial agents;

[0007] Step 2, pre-treat aquatic plant straw;

[0008] Step 3, prepare the polymer substrate;

[0009] Step 4: Dilute the functional microbial agent from Step 1 into a functional microbial agent soaking solution, and soak the pretreated aquatic plant straw from Step 2 in the functional microbial agent soaking solution.

[0010] Step 5: Take out the soaked aquatic plant straw, weave it into multiple regular polygons, and place it on the polymer substrate from Step 3.

[0011] Preferably, the functional microbial agent in step 1 is a mixture of pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria. The nitrifying bacteria, denitrifying bacteria and acetic acid bacteria are pretreated separately, and then the pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria are mixed in a mass ratio of 4:3:3.

[0012] Nitrifying bacteria, denitrifying bacteria, and acetic acid bacteria can degrade nitrogen, phosphorus, and organic pollutants in wastewater, respectively.

[0013] Preferably, the pretreatment method for nitrifying bacteria is as follows: Add dried nitrifying bacteria (Nitrosomonas and Nitrobacter) to the Nutrient Broth, with 8 g of dried nitrifying bacteria added per 800 mL of broth. Maintain the temperature at approximately 28°C and allow to stand for 24 hours. Maintain the nitrifying bacteria in an environment of pH 7.5, checking and adjusting the pH every 2 hours during this process. Adjust the pH using 0.1 mol / L dilute hydrochloric acid or 0.1 mol / L sodium hydroxide solution. When initially adjusting the pH to 7.5, depending on the initial pH of the broth, if the pH is below 7.5, add approximately 1-2 mL of 0.1 mol / L sodium hydroxide solution per 1000 mL of broth; if the pH is above 7.5, add approximately 1-2 mL of 0.1 mol / L dilute hydrochloric acid solution. During subsequent pH checks every 2 hours, if the pH deviates from 7.5 by more than ±0.1, fine-tune according to the above method to ensure that the nitrifying bacteria are always in a suitable pH environment. During this process, an air pump is used to ensure a sufficient oxygen supply, with the oxygen flow rate controlled at 0.5 L / min.

[0014] Preferably, the pretreatment method for denitrifying bacteria is as follows: Denitrifying bacteria (Pseudomonas and Bacillus) are added to a liquid culture medium containing 2 g / L acetic acid and 1 g / L glucose, with 15 g of denitrifying bacteria added per 1000 ml of liquid culture medium. The culture temperature is maintained at 27°C, and the medium is allowed to stand for 30 hours. The denitrifying bacteria are maintained at pH 7, and the pH is monitored and adjusted every 4 hours to ensure sufficient organic carbon in the culture medium, which is then replenished as needed to promote the denitrification process.

[0015] Preferably, the pretreatment method for acetic acid bacteria is as follows: Acetobacter is added to an acetic acid culture medium with a concentration of 3 g / L, along with 0.5 g / L urea and 0.2 g / L potassium dihydrogen phosphate. The amount of acetic acid bacteria added is 12 g per 1000 ml of liquid culture medium. The culture temperature is maintained at 26°C, and the medium is allowed to stand for 40 hours. The acetic acid bacteria are maintained at pH 5, and the pH is monitored and adjusted every 5 hours.

[0016] Furthermore, the mixing method for the functional microbial agent is as follows: First, mix the pretreated nitrifying and denitrifying bacteria at a stirring speed of 100 rpm for 15 minutes. After the activity stabilizes (determined by detecting an ammonia nitrogen degradation rate of over 80%), add the pretreated acetic acid bacteria and continue stirring for 10 minutes. Store the mixed microbial agent in a high-precision refrigerator at 4℃, with temperature fluctuations controlled within ±0.3℃ to avoid freezing and inactivation of the microbial agent.

[0017] Step 2: Select fresh, recently harvested aquatic plant straw, remove excess stems and leaves, wash the surface with distilled water, and cut into strips 10-20 cm long. Different types of straw require different pretreatment methods. The fracture toughness test (Klc test) is used to determine the different flexibility and strength of the straw. The following fracture toughness range can be referenced: cattail straw, approximately 0.3-0.6 MPa·m. 1 / 2 Reed stalks, approximately 1.8-3.5 MPa·m 1 / 2 The following explanation uses cattail stalks and reed stalks as representatives of two different types of straw:

[0018] Preferred pretreatment method for easily processed cattail stalks is as follows: remove excess stems and leaves, wash the surface with distilled water and cut into strips of 10-20 cm in length; soak in sodium hydroxide solvent with a concentration of about 5% until fully soaked, wash with distilled water until no residue remains, and finally dry.

[0019] Soaking in a 5% sodium hydroxide solution can remove impurities and surface substances from cattail stalks. This soaking also alters the surface chemistry of the cattail stalks, exposing or increasing the number of hydrophilic groups such as hydroxyl groups, thus significantly improving their hydrophilicity. The 5% sodium hydroxide solution can also cause slight changes in the cellulose structure of cattail stalks. This modification may reduce the crystallinity of cellulose and weaken intermolecular hydrogen bonds, thereby increasing the accessibility and reactivity of cellulose. Plant fiber materials treated with a similar alkaline solution can exhibit a 20%-30% increase in their adsorption capacity for heavy metal ions.

[0020] Preferred pretreatment method for reed stalks with good flexibility and high strength is as follows: remove excess stems and leaves, wash the surface with distilled water and cut into strips of 10-20 cm in length; soak in a polyvinyl alcohol solution with a concentration of about 10% until fully soaked, wash with distilled water until there are no residues, and finally air dry.

[0021] When reed stalks are soaked in a 10% polyvinyl alcohol (PVA) solution, the PVA molecules penetrate into the fiber structure of the stalks, improving their flexibility and toughness. The treated reed stalks are less prone to breakage or damage during weaving and subsequent use. The presence of PVA also helps to isolate the reed stalks from direct contact with chemicals in wastewater (such as acidic or alkaline substances, oxidizing substances, etc.), enhancing their corrosion resistance. Experimental data shows that in a simulated wastewater immersion environment, the strength retention rate of PVA-treated reed stalks can be increased by 30%-40% within 90 days, exhibiting better durability compared to untreated reed stalks.

[0022] Aquatic plant straw serves as an excellent carrier, playing multiple roles in wastewater treatment. For example, cattail straw exhibits good biocompatibility in biological applications, is less likely to cause adverse reactions, and has a relatively low density, reducing the overall weight of the membrane carrier and making it suitable for large-scale applications. Reed straw naturally possesses good mechanical strength and toughness, as well as high permeability, providing support for the membrane carrier.

[0023] Furthermore, step 3 involves the following steps for creating the polymer substrate: Select a polyethersulfone or polyamide sheet, clean it thoroughly, and cut it into a circular substrate with a radius of 10 mm and a thickness of 8-12 mm; use a micro drill to carve an inscribed regular polygon on the upper and lower surfaces of the circular substrate.

[0024] By optimizing the shape and structure, the mechanical strength of the membrane carrier is enhanced, making it less prone to deformation or damage during long-term operation; the flow characteristics of the fluid are optimized, the flow resistance is reduced, and thus the processing efficiency is improved.

[0025] On both the upper and lower surfaces of the circular base with a thickness of 8-12 mm, grooves 3-5 mm deep are chiseled inward to allow the straw to be well embedded in the grooves, while ensuring that the straw does not protrude excessively from the base surface, thus affecting the flatness and stability of the overall structure.

[0026] Furthermore, the specific steps for soaking the pretreated aquatic plant straw in step 4 are as follows:

[0027] Dilute the functional microbial agent from step 1 with distilled water at a ratio of 1:10 in a glass container to obtain a functional microbial agent soaking solution. Place the pre-treated straw into the functional microbial agent soaking solution, ensuring all straw is completely covered. Maintain the temperature at 25-30℃. During soaking, stir the soaking solution every 10-15 minutes to ensure the microbial agent penetrates evenly into the straw. Soaking time is 30 minutes to 1 hour. After soaking, carefully remove the straw from the soaking solution and place it in a well-ventilated, cool place to dry for 24-48 hours.

[0028] The effects of soaking straw in functional microbial agent solution are:

[0029] 1. Microbial attachment and colonization: Nitrifying bacteria, denitrifying bacteria, and acetic acid bacteria in the functional microbial agents will attach to the surface of the straw during the soaking process. The rough structure of the straw surface and the active sites exposed after pretreatment provide attachment sites for microorganisms.

[0030] 2. Enhanced Biofilm Formation Capacity: The active microorganisms in the functional bacterial agents can promote the rapid formation of biofilm on the surface of straw. In wastewater treatment, biofilm formation significantly increases the contact area and reaction efficiency between microorganisms and pollutants in the wastewater. After biofilm formation, the degradation rate of organic pollutants in wastewater can increase by 2-3 times, and the removal efficiency of nutrients such as nitrogen and phosphorus is also significantly enhanced.

[0031] 3. Enhancing the biological activity of straw. Soaking allows the straw to come into full contact with the microorganisms and their metabolites in the functional bacterial agents, activating some of the straw's own biological activities. On the one hand, enzymes secreted by microorganisms can interact with components such as cellulose and hemicellulose in the straw, promoting their decomposition and transformation, releasing more small molecules. These substances can be further utilized by microorganisms and may also provide additional adsorption sites or reactive groups for wastewater treatment. On the other hand, certain components in the straw may also be activated by microbial metabolism, participating in the removal of pollutants. For example, lignin in straw may be partially degraded under the action of microorganisms.

[0032] 4. Constructing a stable ecosystem. When functional microbial agents are combined with aquatic plant straw, they promote mutual adhesion under natural environmental conditions, forming a relatively stable ecosystem. The straw provides habitat and some nutrients for the microorganisms, which maintain their growth and remove pollutants through metabolic activities. Simultaneously, the metabolic products of the microorganisms can feed back into the properties of the straw and the surrounding environment. This stable ecosystem can continuously perform wastewater treatment functions for a relatively long period and has a certain degree of self-regulation, adapting to fluctuations in wastewater quality and quantity.

[0033] Furthermore, the weaving method for the straw in step 5 is as follows: First, weave small units, then weave them into multiple layers of regular polygons (taking a hexagon as an example): Select a center point, place one end of multiple reed straws at the center point, and distribute the other end in a hexagonal pattern to construct a hexagonal unit frame. Within the unit frame, the first straw is placed vertically, the second horizontally, and the remaining straws are woven in an alternating pattern, with approximately ten sets of straws intersecting on each face. After completing six faces, a hexagonal prism-shaped honeycomb unit is formed.

[0034] Make other honeycomb units using the same method until you reach the required number, approximately 50-70. Place the woven straw honeycomb units layer by layer into the inscribed regular polygonal grooves of the polymer substrate, ensuring that the edges of each layer of straw units are flush with the edges of the adjacent units above and below, leaving a small gap.

[0035] On the outermost side of the groove, select two symmetrical sides and leave one honeycomb unit position on each side. Wrap a thin thread around the regular polygon from both sides to form a complete honeycomb-shaped straw layer. Place it on a circular base and use a press to apply a pressure of about 0.5-3 MPa to compact the straw layer. The temperature should be around 40℃ for 5-15 minutes, resulting in a straw layer thickness of about 15-20 mm. Ensure good adhesion between the straw and the base to form a composite membrane carrier.

[0036] A biofilm carrier, constructed using the aforementioned method, can be stored in a refrigerator at approximately 4°C after fabrication to inhibit excessive microbial growth and degradation. Avoid prolonged storage at room temperature.

[0037] A wastewater treatment system using a biofilm carrier includes a horizontal tank divided into four treatment chambers. An inlet pipe is installed on the side wall of treatment chamber one, and an outlet pipe is installed on the bottom wall of treatment chamber four. Wastewater enters treatment chamber one through the inlet pipe. A straw screen is installed in treatment chamber one, dividing it into two chambers: chamber one and chamber two. Wastewater first enters chamber one, is filtered by the straw screen, and then enters chamber two. A water pipe leading to treatment chamber two is installed in chamber two, and water from chamber two enters the upper part of treatment chamber two through the outlet pipe.

[0038] A straw grid is installed above the second processing chamber. The straw grid is set in a V-shape and is called a straw V-shaped net. A stirring shaft is installed on the bottom wall of the second processing chamber below the straw V-shaped net, and stirring blades are installed on the stirring shaft.

[0039] Treatment chamber 2 and treatment chamber 3 are connected by a water pipe. Treatment chamber 3 is equipped with a biofilm carrier. Treatment chamber 4 is equipped with multiple layers of straw mats from top to bottom, with landscape plants on the top layer of straw mats.

[0040] Furthermore, an aeration device is added. An aeration pipe is installed in treatment chamber two below the straw V-shaped net. The two ends of the aeration pipe are connected to an air inlet pipe and an air outlet pipe, respectively. An aeration main pipe is installed in treatment chamber three, and the air outlet pipe is connected to the aeration main pipe. An aeration fan is installed on the side wall of the treatment chamber below the straw V-shaped net, and an aeration head is installed on the top of the biofilm carrier. The biofilm carrier and the aeration head together form the wastewater treatment unit of treatment chamber three. The aeration head is connected to the aeration main pipe, and the aeration main pipe is connected to treatment chamber four.

[0041] The beneficial effects of this invention are:

[0042] The biofilm carrier of this invention combines the chemical properties and physical strength of functional microbial agents and aquatic plant straw. The composite functional microbial agents effectively remove nitrogen and organic pollutants from polluted water through processes such as ammonia oxidation, nitrification, and denitrification. Furthermore, the active microorganisms in the functional microbial agents promote the formation of a biofilm on the surface of the aquatic plant straw, rapidly activating the system's wastewater treatment capacity. Aquatic plant straw, as a high-quality carrier, can play multiple roles in wastewater treatment. Through reasonable shape design and structural optimization, the mechanical strength of the membrane carrier is enhanced, making it less prone to deformation or damage during prolonged operation; the flow characteristics of the fluid are optimized, reducing flow resistance and thus improving treatment efficiency. The biofilm carrier prepared by this invention can be deployed using processes such as MBBR and SBR, improving wastewater treatment efficiency and providing a new solution for large-scale, diverse wastewater treatment.

[0043] The wastewater treatment system of the present invention can be adapted to various advanced wastewater treatment scenarios, including the purification of polluted river water, municipal sewage, and advanced treatment of industrial wastewater tailwater. It has strong applicability and flexibility and can meet the treatment needs of different occasions. Attached Figure Description

[0044] Figure 1 The wastewater treatment system described in this invention;

[0045] Figure 2 A schematic diagram of a structure in which straw is mounted on the upper surface of a polymer substrate;

[0046] Figure 3 A schematic diagram of a regular polygonal groove structure on the lower surface of a polymer substrate;

[0047] Figure 4 This is a schematic diagram of a straw unit. Detailed Implementation

[0048] The technical solution will be clearly and comprehensively described below with reference to embodiments of the present invention. It should be emphasized that the described embodiments are only a part of the present invention, and not all of them. Furthermore, the details mentioned in this description can be flexibly replaced in implementation, and the present solution can still be successfully implemented.

[0049] Example 1

[0050] This example uses reeds for illustration.

[0051] A method for constructing a biofilm carrier based on aquatic plant straw includes the following steps:

[0052] Step 1: Prepare functional microbial agents; the functional microbial agents are a mixture of pretreated nitrifying bacteria, denitrifying bacteria, and acetic acid bacteria.

[0053] First, nitrifying bacteria, denitrifying bacteria, and acetic acid bacteria are pretreated separately:

[0054] The pretreatment method for nitrifying bacteria is as follows: Add dried nitrifying bacteria (Nitrosomonas and Nitrobacter) to the Nutrient Broth, using 8g of dried nitrifying bacteria per 800mL of broth. Maintain the temperature at approximately 28℃ and let it stand for 24 hours. Keep the nitrifying bacteria at pH 7.5, checking and adjusting the pH every 2 hours during this process. Adjust the pH using 0.1mol / L dilute hydrochloric acid or 0.1mol / L sodium hydroxide solution. When initially adjusting the pH to 7.5, depending on the initial pH of the broth, if the pH is below 7.5, add approximately 1-2mL of 0.1mol / L sodium hydroxide solution per 1000mL of broth; if the pH is above 7.5, add approximately 1-2mL of 0.1mol / L dilute hydrochloric acid solution. During subsequent pH checks every 2 hours, if the pH deviates from 7.5 by more than ±0.1%, fine-tune it using the above method to ensure the nitrifying bacteria are always in a suitable pH environment. During this process, an air pump is used to ensure a sufficient oxygen supply, with the oxygen flow rate controlled at 0.5 L / min.

[0055] The pretreatment method for denitrifying bacteria is as follows: Add denitrifying bacteria (Pseudomonas and Bacillus) to a liquid culture medium containing 2 g / L acetic acid and 1 g / L glucose, with 15 g of denitrifying bacteria added per 1000 ml of liquid culture medium. Maintain the culture temperature at 27°C and let it stand for 30 hours. Keep the denitrifying bacteria at pH 7, monitoring and adjusting the pH every 4 hours to ensure sufficient organic carbon in the culture medium and replenishing it as needed to promote the denitrification process.

[0056] The pretreatment method for acetic acid bacteria is as follows: Add acetic acid bacteria (Acetobacter) to an acetic acid medium with a concentration of 3 g / L, and add 0.5 g / L urea and 0.2 g / L potassium dihydrogen phosphate. The amount of acetic acid bacteria added is 12 g per 1000 ml of liquid medium. Maintain the culture temperature at 26℃ and let it stand for 40 hours. Keep the acetic acid bacteria at pH 5 and monitor and adjust every 5 hours.

[0057] Then, the pretreated nitrifying and denitrifying bacteria were mixed at a stirring speed of 100 rpm for 15 minutes until their activity stabilized (determined by ammonia nitrogen degradation rate exceeding 80%). Then, the pretreated acetic acid bacteria were added, and stirring continued for 10 minutes. The mass ratio of the pretreated nitrifying, denitrifying, and acetic acid bacteria was 4:3:3. The mixed bacterial agent was stored in a high-precision refrigerator at 4℃, with temperature fluctuations controlled within ±0.3℃ to prevent freezing and inactivation of the bacterial agent.

[0058] Step 2, pre-treat aquatic plant straw;

[0059] Remove excess stems and leaves, wash the surface with distilled water, and cut into strips 10-20 cm long. Soak in a polyvinyl alcohol solution with a concentration of about 10% until fully soaked, then wash with distilled water until there are no residues, and finally air dry.

[0060] Step 3, prepare the polymer substrate;

[0061] like Figure 2 , 3 As shown, select polyethersulfone or polyamide sheets, clean them, and cut them into 10mm radius pieces.

[0062] A circular base with a thickness of 8-12 mm; use a miniature electric drill to carve an inscribed regular polygonal groove on the upper and lower surfaces of the circular base.

[0063] Step 4: Dilute the functional microbial agent from Step 1 into a functional microbial agent soaking solution, and soak the pretreated aquatic plant straw from Step 2 in the functional microbial agent soaking solution.

[0064] Dilute the functional microbial agent with distilled water at a ratio of 1:10 in a glass container to obtain a functional microbial agent soaking solution. Place the pre-treated reed straw into the functional microbial agent soaking solution, ensuring all straw is completely covered. Maintain the temperature at 25-30℃. During soaking, stir the soaking solution every 10-15 minutes to ensure the microbial agent penetrates evenly into the straw. Soaking time is 30 minutes to 1 hour. After soaking, carefully remove the straw from the soaking solution and place it in a well-ventilated, cool place to dry for 24-48 hours.

[0065] Step 5: Take out the soaked reed stalks, weave them into multiple regular polygons, and place them on the polymer substrate.

[0066] like Figure 2 As shown, the straw is woven into a honeycomb pattern, with the outer edges of the honeycomb units connected by fine threads to form a closed loop. The loops are marked at points a20 and b21 where the threads are detached. This method effectively secures the units together while maintaining flexibility for disassembly. The edges of each unit are interconnected, and the honeycomb-shaped straw woven layer provides physical support for the membrane carrier, reducing the probability of deformation and collapse during treatment. The honeycomb-shaped straw layer, woven into regular hexagons and processed by rolling, has a thickness of 15-20 mm. After the functional microbial agent is combined with the aquatic plant straw, under natural environmental conditions (water flow, temperature, and nutrient concentration), they promote adhesion, allowing microorganisms to colonize the straw surface and form a stable ecosystem.

[0067] Each unit's six sides are woven from orderly arranged straw, enhancing its load-bearing capacity and compressive strength. Furthermore, the units are stacked with a certain offset, effectively increasing structural strength while reducing close contact between adjacent layers to prevent water blockage.

[0068] like Figure 3 As shown, the circular substrate 23 is made of polyethersulfone or polyamide material, with a thickness of 8-12 mm. It has a circular structure with an inscribed regular polygon in the center to facilitate the outflow of treated wastewater from the membrane carrier. The substrate layer provides support for the entire membrane carrier.

[0069] In this invention, the straw layer 22 in the composite membrane carrier serves as both a bio-based material and the main filler, providing a primary attachment and growth site for microorganisms. The suitable structure and nutrients of this layer promote the growth and metabolism of microorganisms such as polyphosphate-accumulating bacteria, reducing bacteria, and various anaerobic and aerobic bacteria, thereby removing nitrogen and phosphorus pollutants, phenols, hydrocarbons, alcohols, and lead (Pb) from wastewater. 2+ ), cadmium (Cd 2+ ), mercury (Hg) 2+ Heavy metal pollutants such as 1000 ions are transformed into harmless substances, achieving deep purification.

[0070] Example 2

[0071] The reed stalks processed in step 4 of Example 1 are woven into a grid. The method is as follows: Take two reed stalks and place them parallel to each other as the "warp" of the grid. Then, take another reed stalk and thread it perpendicular to the first two reed stalks (as the "weft") from below the two "warp" reed stalks, and then thread it down above the intersection of the two "warp" reed stalks. Pull it tight to complete the first intersection weaving point. Continue to add "weft" reed stalks in this way, and maintain the tightness of each intersection during the weaving process to fix the reed stalks together, thus weaving a reed grid with a certain width and length.

[0072] Based on the size of the wastewater treatment plant inlet or the section that needs filtration, multiple such grids are woven together, then spliced ​​together and fixed in the appropriate position of the wastewater treatment plant to provide physical support, buffering, and uniform water distribution.

[0073] like Figure 1 As shown, a wastewater treatment system using a biofilm carrier:

[0074] Wastewater enters treatment chamber one of the wastewater treatment system through inlet pipe 1. Treatment chamber one is equipped with a reed straw screen 3, which divides it into two chambers: chamber one and chamber two. Wastewater first enters chamber one, is filtered by the reed straw screen, and then enters chamber two. A water pipe leads to chamber two, and the water from chamber two flows through an outlet pipe to the top of chamber two. Above treatment chamber two, a reed straw screen is installed in a V-shape, referred to here as the reed straw V-shaped mesh 4. Below the reed straw V-shaped mesh, within treatment chamber two, an aeration pipe 7 is installed. The two ends of the aeration pipe are connected to an air inlet pipe 5 and an air outlet pipe 6, respectively. The air outlet pipe is connected to the main aeration pipe 14 located in treatment chamber three. An aeration fan 8 is installed on the side wall of the treatment chamber below the reed straw V-shaped mesh, and a stirring shaft 9 with stirring blades 10 is installed on the bottom wall of treatment chamber two below the aeration pipe 7. A flow guide plate 11 is installed between the inner bottom wall and the side wall of the second processing chamber.

[0075] Treatment chamber two and treatment chamber three are connected by a water pipe 12. Treatment chamber three is equipped with a biofilm carrier 16 prepared in Example 1, and an aeration head 15 is installed on the top of the biofilm carrier. The biofilm carrier 16 and the aeration head 15 together constitute the wastewater treatment unit 13 of treatment chamber three. The aeration head is connected to the aeration main pipe 14, and the aeration main pipe 14 is connected to treatment chamber four. Treatment chamber four is equipped with multiple layers of reed straw mats 18 from top to bottom, and landscape plants 17 are installed on the top layer of reed straw mats. A water outlet 19 is installed at the bottom of treatment chamber four.

[0076] A valve 2 is installed on the inlet pipe. Wastewater flows through the aforementioned reed straw grid 3. By adjusting the valve opening, the rate at which wastewater enters the system can be precisely controlled to match the processing capacity of subsequent treatment units, thus maintaining the stability of the entire wastewater treatment system. For example, when a subsequent treatment unit is under maintenance or its processing capacity is temporarily reduced, the valve can be adjusted to decrease the amount of wastewater entering the system.

[0077] Reed stalk bar screens can effectively block larger solid debris in sewage, ensuring the smooth operation of subsequent treatment processes.

[0078] Wastewater exiting treatment chamber one enters treatment chamber two through a V-shaped net made of reeds and straw. After aeration, it is rotated and stirred within treatment chamber two. As the wastewater flows through the V-shaped net, the water flow is divided into multiple smaller streams by the net, preventing solid particles in the wastewater from continuously settling in one direction.

[0079] After the aeration blower 8 starts, outside air is drawn in, transmitted through the air inlet pipe 5, and delivered to the aeration main pipe 14 through the air outlet pipe 6. The aeration main pipe 14 acts as an air distribution channel, evenly distributing air to each aeration head 15, which then disperses the air into tiny bubbles and releases them into the wastewater. This aeration process increases the dissolved oxygen concentration in the wastewater, creating a favorable oxygen-rich environment for subsequent aerobic microbial decomposition of organic pollutants, and promoting efficient aerobic biochemical reactions. Simultaneously, the stirring shaft 9 drives the stirring blades 10 to rotate, intensely agitating the wastewater. On one hand, agitation evenly disperses the bubbles generated by aeration in the wastewater, increasing the contact area between oxygen and wastewater, thereby improving oxygen transfer efficiency; on the other hand, agitation promotes thorough mixing of wastewater and microorganisms, ensuring that the microorganisms can fully contact the organic pollutants in the wastewater.

[0080] The guide plate 11 guides the flow of sewage in this area. After flowing out of treatment chamber two, the sewage enters sewage treatment unit 13 for primary sewage treatment. The sewage treated in treatment chamber three is pumped into treatment chamber four, passing through multiple layers of reed straw mats 18 from top to bottom, where residual dissolved pollutants are absorbed. The landscape plants 17 planted on the reed mats not only add natural beauty to the sewage treatment area, but their roots can also absorb some nutrients from the sewage, such as nitrogen and phosphorus, as they grow in the sewage. While deeply purifying the sewage, this further reduces the nutrient content in the sewage, prevents eutrophication, and helps maintain the balance of the entire sewage treatment ecosystem. During this process, suspended solids and other substances in the sewage gradually settle, further separating into a clear liquid.

[0081] Example 3

[0082] This embodiment uses a composite membrane carrier made of rice straw and functional microbial agents to treat domestic sewage. Domestic sewage has a high content of organic matter, nitrogen, phosphorus, and suspended solids, making it suitable for composite membrane carriers made from straw, whose main function is to provide a carbon source. Rice straw is rich in organic matter and can serve as a carbon source for microorganisms during sewage treatment, promoting their growth and reproduction.

[0083] The prepared straw grid, straw V-shaped mesh, and straw composite membrane carrier are fixed inside the SBR or MBBR reactor. Before placing the membrane carrier, the reactor is filled with water, and then the membrane carrier frame is slowly placed into the bottom of the reactor to ensure that the membrane carrier is completely submerged in the wastewater and evenly distributed.

[0084] The operating mode is to allow water to enter for 15 minutes, with the water flow rate controlled at 5m³ / min. 3 / h, allowing wastewater to slowly enter the reactor to avoid impacting the membrane carrier and microorganisms; aeration for 2 hours, with an aeration intensity of 10m. 3Aeration is carried out at a rate of 60 rpm for 2 hours using a mechanical agitator to ensure sufficient contact between the wastewater and the microorganisms on the membrane carrier surface; aeration continues for 2 hours; agitation continues for 2 hours; sedimentation continues for 2 hours at a rate controlled at 0.8 m / h, allowing solid particles in the treated wastewater to settle to the bottom of the reactor for easy effluent discharge; effluent discharge is carried out for 15 minutes at a flow rate controlled at 5 m³ / h. 3 The supernatant is discharged from the reactor at a rate of 1 h; then left idle for 1.5 h to allow the microorganisms to recover their activity in a relatively stable environment. Two cycles are run daily, with a total treatment cycle of 20 days.

[0085] Treatment effectiveness evaluation: Wastewater samples were collected every two days before and during treatment to test COD, TP, TN, and NH4. + -N and other water quality indicators.

[0086] Before treatment, the domestic sewage contained approximately 502.50 mg / L COD, 8.74 mg / L TP, 63.20 mg / L TN, and NH4+. + The -N content is approximately 39.87 mg / L.

[0087] After treatment, calculations showed that the COD removal rate reached 85.33%, with the final concentration reduced to below 73.72 mg / L; the TP removal rate reached 90.13%, with the concentration reduced to below 0.86 mg / L; the TN removal rate reached 82.35%, with the concentration reduced to below 11.15 mg / L; and NH4... + -N removal rate reached 97.07%, and content was reduced to below 1.17 mg / L. This significantly reduced the pollutant content in wastewater, resulting in a marked improvement in water quality.

[0088] Similarly, when dealing with wastewater such as food processing wastewater with high organic matter content, it is advisable to add a certain amount of rice straw for compound treatment during actual operation.

[0089] Example 4

[0090] This embodiment uses a composite membrane carrier made of reed straw and functional microbial agents to treat wastewater containing large amounts of cellulose, lignin, and chemical additives, taking papermaking wastewater as an example. Reed straw has high mechanical strength and toughness, which can provide support for the membrane carrier.

[0091] The reed straw composite membrane carrier is loaded into specially designed suspended packing balls, with each ball filled with an appropriate amount of membrane carrier. These packing balls are then placed into an SBR or MBBR reactor. The packing balls are made of corrosion-resistant, high-strength plastic with numerous small pores approximately 0.5 cm in diameter on their surface. Before adding the packing balls, the reactor is filled with water, and then the packing balls are slowly and evenly added to the reactor, allowing them to suspend freely within the reactor.

[0092] The operating mode is to allow water to enter for 15 minutes, with the water flow rate controlled at 4m³ / min. 3 Because the high concentration of toxic chemicals in wastewater from the paper industry inhibits microbial growth, the influent flow rate must be strictly controlled to avoid excessive impact on microorganisms; aeration for 2 hours, with an aeration intensity of 8 m³ / h. 3 / h, using perforated pipe aeration to provide oxygen for microorganisms; stirring for 2 hours at a speed of 50 rpm to ensure full contact between wastewater and membrane carrier; aeration for 2 hours; stirring for 2 hours; sedimentation for 2 hours at a sedimentation rate of 0.6 m / h to allow solid particles to settle; effluent discharge for 15 minutes, with the effluent flow rate controlled at 4 m³ / h. 3 The system operates at a rate of 1 hour per hour, discharging treated wastewater; then allows 1.5 hours of idle time to allow microorganisms to regain activity. It runs two cycles per day, with a total treatment cycle of 20 days.

[0093] Treatment effect evaluation:

[0094] Before treatment, the wastewater from the paper mill contained approximately 826.82 mg / L of BOD, approximately 1536.51 mg / L of COD, approximately 5.11 mg / L of heavy metal ions (such as lead, mercury, cadmium, etc., calculated as total heavy metal ion concentration), and approximately 1036.20 mg / L of chloride.

[0095] Water samples were collected and tested regularly during the treatment process. After treatment, calculations showed that the BOD removal rate reached 92.49%, with the concentration reduced to below 62.09 mg / L; the COD removal rate reached 91.24%, with the concentration reduced to below 134.60 mg / L; the heavy metal ion removal rate reached 96.93%, with the concentration reduced to below 0.16 mg / L; and the chloride removal rate reached 85.45%, with the concentration reduced to below 150.77 mg / L. This effectively reduced the pollutant content in the wastewater and mitigated environmental pollution.

[0096] It should be emphasized that all the above embodiments embody the same inventive concept. Details in some embodiments may not be fully elaborated, but can be supplemented by referring to the content of other embodiments.

[0097] It should be understood that any parts of this invention not described in detail belong to the prior art. The above description, in conjunction with the accompanying drawings, is merely a specific implementation method and process of this invention, but the scope of protection of this invention is not limited thereto. Any person skilled in the art should understand that this is merely illustrative, and various changes and substitutions can be made to this implementation method without departing from the essence of this invention. The scope of this invention is defined only by the appended claims.

Claims

1. A method for constructing a biofilm carrier based on aquatic plant straw, characterized in that, Includes the following steps: Step 1: Prepare functional microbial agents; Step 2, pre-treat aquatic plant straw; Step 3, prepare the polymer substrate; Step 4: Dilute the functional microbial agent from Step 1 into a functional microbial agent soaking solution, and soak the pretreated aquatic plant straw from Step 2 in the functional microbial agent soaking solution. Step 5: Take out the soaked aquatic plant straw, weave it into multiple regular polygons, and place it on the polymer substrate from Step 3; The pretreatment method for aquatic plant straw with low fracture toughness in step 2 is as follows: remove excess stems and leaves, wash the surface with distilled water and cut it into strips of 10-20 cm in length; soak it in a 5% sodium hydroxide solvent, and after it is fully soaked, wash it with distilled water until there are no residues, and finally dry it. The pretreatment method for aquatic plant straw with high fracture toughness in step 2 is as follows: remove excess stems and leaves, wash the surface with distilled water and cut it into strips of 10-20 cm in length; soak it in a 10% polyvinyl alcohol solution, and after it is fully soaked, wash it with distilled water until there are no residues, and finally air dry it. Step 3 involves the following steps to create the polymer substrate: Select a polyethersulfone or polyamide sheet, clean it thoroughly, and cut it into a circular substrate with a radius of 10 mm and a thickness of 8-12 mm; each of the upper and lower surfaces of the circular substrate has a regular polygonal groove.

2. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that, The specific steps for soaking the pretreated aquatic plant straw in step 4 are as follows: Dilute the functional microbial agent from step 1 with distilled water at a ratio of 1:10 in a glass container to obtain a functional microbial agent soaking solution. Place the pretreated aquatic plant straw into the functional microbial agent soaking solution, ensuring that all aquatic plant straw is covered by the soaking solution. Maintain the temperature at 25-30°C. During the soaking process, stir the soaking solution every 10-15 minutes to ensure that the microbial agent penetrates evenly into the interior of the aquatic plant straw. The soaking time is 30 minutes to 1 hour. After soaking, carefully remove the aquatic plant straw from the soaking solution and place it in a well-ventilated, cool place to dry for 24-48 hours.

3. A biofilm carrier, characterized in that, It is constructed by the method described in any one of claims 1-2.

4. A wastewater treatment system using the biofilm carrier described in claim 3, characterized in that, The system includes a horizontal tank, which is divided into four treatment chambers. The side wall of treatment chamber one is equipped with an inlet pipe, and the bottom wall of treatment chamber four is equipped with an outlet pipe. Wastewater enters treatment chamber one of the wastewater treatment system through the inlet pipe. Treatment chamber one is equipped with a straw screen, which divides treatment chamber one into two chambers, namely chamber one and chamber two. Wastewater first enters chamber one, is filtered by the straw screen, and then enters chamber two. A water pipe is installed in chamber two to lead to treatment chamber two. Water from chamber two enters the upper part of treatment chamber two through the water pipe. A straw grid is installed above the second processing chamber. The straw grid is set in a V-shape and is called a straw V-shaped net. A stirring shaft is installed on the bottom wall of the second processing chamber below the straw V-shaped net, and stirring blades are installed on the stirring shaft. Treatment chamber 2 and treatment chamber 3 are connected by a water pipe. Treatment chamber 3 is equipped with a biofilm carrier. Treatment chamber 4 is equipped with multiple layers of straw mats from top to bottom, with landscape plants on the top layer of straw mats.

5. The wastewater treatment system according to claim 4, characterized in that, An aeration pipe is installed in treatment chamber two below the straw V-shaped net. The two ends of the aeration pipe are connected to an air inlet pipe and an air outlet pipe, respectively. An aeration main pipe is installed in treatment chamber three, and the air outlet pipe is connected to the aeration main pipe. An aeration fan is installed on the side wall of the treatment chamber below the straw V-shaped net, and an aeration head is installed on the top of the biofilm carrier. The biofilm carrier and the aeration head together form the wastewater treatment unit of treatment chamber three. The aeration head is connected to the aeration main pipe, and the aeration main pipe is connected to treatment chamber four.

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