Biofilm carrier construction method based on aquatic plant straws

Abstract

The invention discloses a biofilm carrier construction method based on aquatic plant straws. The biofilm carrier construction method comprises the following steps: preparing a functional fungicide; pretreating aquatic plant straws; manufacturing a polymer substrate; diluting a functional bacterial agent into a functional bacterial agent soaking solution, and soaking the pretreated aquatic plant straws in the functional bacterial agent soaking solution; taking out the soaked aquatic plant straws, weaving into a multi-layer regular polygon, and placing on a polymer substrate. The biofilm carrier disclosed by the invention combines the chemical characteristics and physical strength of the functional fungicide and the aquatic plant straws. The composite functional bacterial agent can effectively remove nitrogen and organic pollutants in polluted water through ammoxidation, nitrification, denitrification and other processes. As a high-quality carrier, the aquatic plant straw can play a plurality of roles in sewage treatment.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and specifically comprises a method for constructing a biofilm carrier based on aquatic plant straw and its application. Background Art

[0002] It is a common method to use biofilm-based tailwater to deeply purify micro-polluted water bodies or tailwater from sewage treatment plants. Plant straw can be used as a high-quality biofilm carrier material. For example, the application number is 201810492973X, and the invention name is a biofilm carrier device for sewage treatment based on soybean straw and its use method. However, different types of plant straw usually have different physical and chemical properties, and play different roles as biofilm carriers and microbial carbon sources. Moreover, appropriate carriers can not only use their biological and chemical properties to provide a good attachment site for microorganisms, but also play other roles, such as providing carbon sources, structural support, etc. Summary of the invention

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

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

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

[0006] Step 1, preparing a functional bacterial agent;

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

[0008] Step 3, preparing a polymer substrate;

[0009] Step 4, diluting the functional bacterial agent in step 1 into a functional bacterial agent soaking solution, and soaking the aquatic plant straw pretreated in step 2 in the functional bacterial agent soaking solution;

[0010] Step 5, taking out the soaked aquatic plant straws, weaving them into multi-layer regular polygons, and placing them on the polymer substrate of step 3.

[0011] Preferably, the functional bacterial agent in step 1 is a mixed bacteria of pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria, and 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 sewage respectively.

[0013] Preferably, the pretreatment method for nitrifying bacteria is: add dried nitrifying bacteria (Nitrosomonas and Nitrobacter) to the culture medium (Nutrient Broth), and the amount of dried nitrifying bacteria added to each 800mL culture medium is 8g. The temperature is maintained at about 28°C and allowed to stand for 24 hours. The nitrifying bacteria are maintained in an environment of pH=7.5, and the pH is detected and adjusted every 2 hours during the process. Use 0.1mol / L dilute hydrochloric acid or 0.1mol / L sodium hydroxide solution to adjust the pH. When the pH is initially adjusted to 7.5, according to the initial pH of the culture medium, if the pH is lower than 7.5, about 1-2mL of 0.1mol / L sodium hydroxide solution is added to each 1000mL culture medium; if the pH is higher than 7.5, about 1-2mL of 0.1mol / L dilute hydrochloric acid solution is added. In the subsequent pH detection process 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 sufficient oxygen supply, and the oxygen flow rate is controlled at 0.5L / min.

[0014] Preferably, the pretreatment method for denitrifying bacteria is: add denitrifying bacteria (Pseudomonas and Bacillus) to a liquid culture medium with a concentration of 2g / L acetic acid and 1g / L glucose, and add 15g of denitrifying bacteria per 1000ml of liquid culture medium. The culture temperature is maintained at 27°C and allowed to stand for 30 hours. Maintain the denitrifying bacteria in an environment of pH=7, detect and adjust the pH every 4 hours, ensure that the culture medium contains sufficient organic carbon and replenish it in time to promote the denitrification process.

[0015] Preferably, the pretreatment method for acetic acid bacteria is: add acetic acid bacteria (Acetobacter) to an acetic acid medium with a concentration of 3g / L, and add 0.5g / L of urea and 0.2g / L of potassium dihydrogen phosphate. The amount of acetic acid bacteria added per 1000ml liquid culture medium is 12g. The culture temperature is maintained at 26°C and allowed to stand for 40 hours. Maintain the acetic acid bacteria in an environment of pH=5 and monitor and adjust every 5 hours.

[0016] Furthermore, the mixing method of the functional bacterial agent is as follows: first, pre-treated nitrifying bacteria and denitrifying bacteria are mixed at a stirring speed of 100 rpm, stirred for 15 minutes, and after the activity is stabilized (determined by detecting that the ammonia nitrogen degradation rate reaches more than 80%), the pre-treated acetic acid bacteria are added and stirred for 10 minutes. The mixed bacterial agent is stored in a high-precision refrigerator at 4°C, and the temperature fluctuation range is controlled within ±0.3°C to avoid freezing and inactivation of the bacterial agent.

[0017] In step 2, select fresh, newly harvested aquatic plant straw, remove excess stems and leaves, wash the surface with distilled water, and cut into 10-20 cm strips. Different types of straw use different pretreatment methods. The fracture toughness test (Klc test) is used to judge the different flexibility and strength of straw. The following fracture toughness range can be used as a reference: Cattail straw, about 0.3-0.6MPa·m 1 / 2 ; Reed straw, about 1.8-3.5MPa·m 1 / 2 The following uses cattail straw and reed straw as representatives of two different types of straw for illustration:

[0018] Preferably, the pretreatment method for the easy-to-process cattail straw is: remove excess stems and leaves, wash the surface with distilled water and cut into 10-20 cm strips; soak in a sodium hydroxide solvent with a concentration of about 5%, after being fully soaked, wash with distilled water until there is no residue, and finally dry.

[0019] Soaking in 5% sodium hydroxide solution can remove impurities and surface substances on the surface of cattail straw; soaking in sodium hydroxide solution can change the surface chemical properties of cattail straw, exposing or increasing hydrophilic groups such as hydroxyl groups on its surface, thereby significantly improving the hydrophilicity of the straw. 5% sodium hydroxide solution will cause slight changes in the cellulose structure of cattail straw to a certain extent. This modification may reduce the crystallinity of cellulose and weaken intermolecular hydrogen bonds, thereby increasing the accessibility and reactivity of cellulose. The adsorption capacity of plant fiber materials for heavy metal ions after similar alkaline treatment can be increased by 20%-30%.

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

[0021] When reed straw is soaked in a 10% polyvinyl alcohol solution, the polyvinyl alcohol molecules will penetrate into the fiber structure of the straw, improving the flexibility and toughness of the reed straw. The treated reed straw is not easy to break or damage during weaving and subsequent use; the presence of polyvinyl alcohol can also isolate the direct contact between chemical substances in sewage (such as acidic or alkaline substances, oxidizing substances, etc.) and reed straw to a certain extent, enhancing its corrosion resistance. Experimental data show that the strength retention rate of reed straw treated with polyvinyl alcohol can be increased by 30%-40% within 90 days in a simulated sewage immersion environment, and it has better durability than untreated reed straw.

[0022] As a high-quality carrier, aquatic plant straw can play a variety of roles in sewage treatment. For example, cattail straw has good biocompatibility in biological applications, is not easy to cause adverse reactions, and has a relatively low density, which can reduce the total weight of the membrane carrier and is suitable for large-scale applications; reed straw naturally has good mechanical strength and toughness, and is highly permeable, which can provide support for the membrane carrier.

[0023] Furthermore, the process of making the polymer substrate in step 3 is: selecting a polyethersulfone or polyamide sheet, cleaning it and cutting it into a circular substrate with a radius of 10 mm and a thickness of 8-12 mm; using a micro electric drill to chisel out an inscribed regular polygon on the upper and lower surfaces of the circular substrate.

[0024] Through reasonable shape design and structural optimization, the mechanical strength of the membrane carrier is enhanced, making it less likely to deform or damage during long-term operation; the flow characteristics of the fluid are optimized, the flow resistance is reduced, and the processing efficiency is improved.

[0025] 3-5mm deep grooves are chiseled inward on the upper and lower surfaces of the circular base with a thickness of 8-12mm, so that the straw can be better embedded in the grooves, while ensuring that the straw will not protrude excessively from the surface of the base, affecting the flatness and stability of the overall structure.

[0026] Furthermore, the specific method of soaking the pretreated aquatic plant straw in step 4 is:

[0027] The functional bacterial agent in step 1 is diluted with distilled water in a glass container at a ratio of 1:10 to obtain a functional bacterial agent soaking solution; the pretreated straw is placed in the functional bacterial agent soaking solution to ensure that all the straw is covered by the soaking solution, and the temperature is maintained at 25-30°C. During the soaking process, the soaking solution is stirred at a frequency of once every 10-15 minutes to ensure that the bacterial agent is evenly penetrated into the straw, and the soaking time is 30 minutes to 1 hour. After the soaking is completed, the straw is carefully removed from the soaking solution, placed in a well-ventilated and cool place, and dried for 24-48 hours.

[0028] The effects of functional bacterial agent soaking liquid on straw are:

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

[0030] 2. Enhance the ability to form biofilm: The active microorganisms in the functional bacterial agent can promote the rapid formation of biofilm on the surface of straw. In the sewage treatment process, the formation of biofilm can greatly increase the contact area and reaction efficiency between microorganisms and pollutants in sewage. After the biofilm is formed, the degradation rate of organic pollutants in sewage can be increased by 2-3 times, and the removal effect of nutrients such as nitrogen and phosphorus is also significantly enhanced.

[0031] 3. Improve the biological activity of straw. Soaking allows the straw to fully contact with the microorganisms and their metabolites in the functional bacterial agent, activating some of the biological activities of the straw itself. On the one hand, the enzymes secreted by microorganisms can react with the cellulose, hemicellulose and other components in the straw, promote their decomposition and transformation, and release more small molecules. These substances can be further utilized by microorganisms, and may also provide additional adsorption sites or reactive groups for sewage treatment. On the other hand, some components in the straw may also be activated by microbial metabolism and participate in the removal of pollutants. For example, the lignin in the straw may be partially degraded under the action of microorganisms.

[0032] 4. Build a stable ecosystem. After the functional bacteria agent is combined with the aquatic plant straw, they promote each other's attachment under natural environmental conditions, forming a relatively stable ecosystem. The straw provides a habitat and some nutrients for microorganisms, and the microorganisms maintain their own growth and remove pollutants through metabolic activities. At the same time, the metabolites of microorganisms can feedback and affect the properties of the straw and the surrounding environment. This stable ecosystem can continue to play the sewage treatment function for a long time, and has a certain self-regulation ability, which can adapt to certain fluctuations in sewage quality and water volume.

[0033] Furthermore, in step 5, the weaving method of the straw is: first weave small units, and then weave into multi-layer regular polygons (taking hexagons as an example): select a center point, place one end of multiple reed straws at the center point, and distribute the other ends in a hexagon to construct a hexagonal unit frame. In the unit frame, the first straw is placed vertically, the second is placed horizontally, and the remaining straws are woven front and back in an interlaced manner. About ten groups of straws are crossed on each face, and after completing six faces, a hexagonal honeycomb unit is formed.

[0034] The other honeycomb units are made in the same way until the required number is reached, about 50-70. The woven straw honeycomb units are placed layer by layer in the inscribed regular polygon grooves of the polymer substrate, and the edges of each layer of straw units are attached to the edges of the upper and lower adjacent units, leaving a small gap.

[0035] Select two symmetrical sides on the outermost side of the groove to leave a position for a honeycomb unit, and wrap the thin wire around the regular polygon from both sides to form a complete honeycomb straw layer. Place it on a circular base, use a press to apply a pressure of about 0.5-3MPa to roll the straw layer, the temperature is about 40℃, the time is 5-15 minutes, and the thickness of the straw layer is about 15-20mm. Ensure that the straw is well bonded to the base to form a composite membrane carrier.

[0036] A biofilm carrier is constructed by the above method. After the biofilm carrier is manufactured, it can be stored in a refrigerator at about 4°C to inhibit excessive growth and degradation of microorganisms. Note that it should be avoided to store it at room temperature for a long time.

[0037] A sewage treatment system using a biofilm carrier comprises a horizontal box body, which is divided into four treatment chambers. A water inlet pipe is arranged on the side wall of treatment chamber one, and a water outlet pipe is arranged on the bottom wall of treatment chamber four. Sewage enters treatment chamber one of the sewage treatment system from the water inlet pipe. A straw grille is arranged in treatment chamber one. The straw grille divides treatment chamber one into two chambers, namely chamber one and chamber two. Sewage first enters chamber one, and enters chamber two after being filtered by the straw grille. A water pipe leading to treatment chamber two is arranged in chamber two. Water in chamber two enters the upper part of treatment chamber two through the water outlet pipe.

[0038] A straw grille is arranged above the second processing chamber, and the straw grille is arranged in a V shape, which is called a straw V-shaped net. A stirring shaft is arranged on the inner bottom wall of the second processing chamber below the straw V-shaped net, and a stirring blade is arranged on the stirring shaft;

[0039] Treatment chamber two and treatment chamber three are connected by a connecting water pipe, and a biofilm carrier is arranged in treatment chamber three; treatment chamber four is provided with multiple layers of straw mats from top to bottom, and landscape plants are arranged on the top layer of straw mats.

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

[0041] The beneficial effects of the present invention are:

[0042] The biofilm carrier of the present invention combines the chemical properties and physical strength of functional bacteria and aquatic plant straw. The composite functional bacteria can effectively remove nitrogen and organic pollutants in polluted water through processes such as ammonia oxidation, nitrification, and denitrification. In addition, the active microorganisms in the functional bacteria can promote the formation of biofilms on the surface of aquatic plant straws, and quickly start the sewage treatment capacity of the system. As a high-quality carrier, aquatic plant straws can play a variety of functions in sewage treatment. Through reasonable shape design and structural optimization, the mechanical strength of the membrane carrier is enhanced, so that it is not easy to deform or damage during long-term operation; the flow characteristics of the fluid are optimized, the flow resistance is reduced, and the treatment efficiency is improved. The biofilm carrier prepared by the present invention can be carried out based on MBBR, SBR and other processes to improve the sewage treatment efficiency, providing a new solution for a wide range of different types of sewage treatment.

[0043] The sewage treatment system of the present invention can adapt to a variety of sewage deep treatment scenarios, including purification of polluted river water, deep treatment of municipal sewage and industrial wastewater tail water, etc. It has strong applicability and flexibility and can meet the treatment needs of different occasions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 The sewage treatment system of the present invention;

[0045] Figure 2 Schematic diagram of the structure with straw installed on the upper surface of the polymer substrate;

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

[0047] Figure 4 Schematic diagram of a straw unit. DETAILED DESCRIPTION

[0048] The following will be combined with the embodiments of the present invention to clearly and comprehensively describe the technical solution. It should be emphasized that the described embodiments are only part of the present invention, not all embodiments. And the details mentioned in this description can be flexibly replaced when implementing the solution, and the solution can also be successfully implemented.

[0049] Example 1

[0050] This embodiment is described using reeds.

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

[0052] Step 1, preparing a functional bacterial agent; the functional bacterial agent is a pre-treated mixed bacteria of nitrifying bacteria, denitrifying bacteria and acetic acid bacteria,

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

[0054] The pretreatment method for nitrifying bacteria is: add dried nitrifying bacteria (Nitrosomonas and Nitrobacter) to the culture medium (Nutrient Broth), and the amount of dried nitrifying bacteria added to each 800mL culture medium is 8g. The temperature is maintained at about 28°C and allowed to stand for 24 hours. Maintain the nitrifying bacteria in an environment of pH = 7.5, and test and adjust the pH every 2 hours during the process. Use 0.1mol / L dilute hydrochloric acid or 0.1mol / L sodium hydroxide solution to adjust the pH. When the pH is initially adjusted to 7.5, according to the initial pH of the culture medium, if the pH is lower than 7.5, add about 1-2mL of 0.1mol / L sodium hydroxide solution to each 1000mL culture medium; if the pH is higher than 7.5, add about 1-2mL of 0.1mol / L dilute hydrochloric acid solution. In the subsequent pH detection process 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 sufficient oxygen supply, and the oxygen flow rate is controlled at 0.5L / min.

[0055] The pretreatment method for denitrifying bacteria is: add denitrifying bacteria (Pseudomonas and Bacillus) to a liquid culture medium with a concentration of 2g / L acetic acid and 1g / L glucose, and add 15g of denitrifying bacteria to every 1000ml of liquid culture medium. The culture temperature is maintained at 27°C and allowed to stand for 30 hours. Maintain the denitrifying bacteria in an environment of pH=7, detect and adjust the pH every 4 hours to ensure that the culture medium contains sufficient organic carbon and is supplemented in time to promote the denitrification process.

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

[0057] Then, the pretreated nitrifying bacteria and denitrifying bacteria were mixed at a stirring speed of 100 rpm, stirred for 15 minutes, and after their activity was stabilized (determined by detecting that the ammonia nitrogen degradation rate reached more than 80%), the pretreated acetic acid bacteria were added and stirred for 10 minutes, wherein the mass ratio of the pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria was 4:3:3. The mixed bacterial agent was stored in a high-precision refrigerator at 4°C, and the temperature fluctuation range was controlled at ±0.3°C to avoid freezing and inactivation of the bacterial agent.

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

[0059] Remove excess stems and leaves, clean the surface with distilled water and cut into 10-20 cm strips; soak in a polyvinyl alcohol solution with a concentration of about 10%, and after it is fully soaked, wash with distilled water until there is no residue, and finally air-dry.

[0060] Step 3, preparing a polymer substrate;

[0061] like Figure 2 , 3 As shown, select polyethersulfone or polyamide sheet, clean it and cut it into a radius of 10

[0062] ㎜, a circular base with a thickness of 8-12㎜; use a micro electric drill to chisel out an inscribed regular polygon groove on the upper and lower surfaces of the circular base.

[0063] Step 4, diluting the functional bacterial agent in step 1 into a functional bacterial agent soaking solution, and soaking the aquatic plant straw pretreated in step 2 in the functional bacterial agent soaking solution;

[0064] Dilute the functional bacterial agent with distilled water in a glass container at a ratio of 1:10 to obtain a functional bacterial agent soaking solution; place the pretreated reed straw in the functional bacterial agent soaking solution, ensure that all the straw is covered by the soaking solution, maintain the temperature at 25-30°C, stir the soaking solution at a frequency of 10-15 minutes during the soaking process to ensure that the bacterial agent evenly penetrates into the straw, and the soaking time is 30 minutes to 1 hour. After the soaking is completed, carefully remove the straw from the soaking solution, place it in a well-ventilated and cool place, and dry it for 24-48 hours.

[0065] Step 5, taking out the soaked reed straw, weaving it into multiple layers of regular polygons, and placing it on a polymer substrate.

[0066] like Figure 2 As shown, the straw is woven into a honeycomb shape, and the outer edge of the honeycomb unit is connected by a thin wire to form a closed ring, which is closed at the thin wire removal points a20 and b21 marked in the figure. This method can effectively fix the units together while retaining the flexibility of disassembly. The edges of each unit are connected to each other, and the honeycomb straw woven layer provides physical support for the membrane carrier, reducing the probability of deformation and collapse of the membrane during treatment. The honeycomb straw layer arranged and woven into a regular hexagon and rolled has a thickness of 15-20 mm. After the functional bacterial agent is compounded with the aquatic plant straw, it promotes mutual attachment under natural environmental conditions (water flow, temperature and nutrient concentration), allowing microorganisms to colonize on the straw surface to form a stable ecosystem.

[0067] The six sides of each unit are woven from straw in an orderly manner to enhance the load-bearing capacity and compression resistance. The units are stacked with a certain offset, which effectively enhances the structural strength while reducing the close contact between adjacent layers to avoid water blockage.

[0068] like Figure 3 As shown, the circular base 23 is made of polyethersulfone or polyamide material, with a thickness of 8-12 mm and a circular structure with a regular polygonal hollow in the middle to facilitate the sewage to flow out of the membrane carrier after treatment. The base layer provides support for the entire membrane carrier.

[0069] In the present invention, the straw layer 22 in the composite membrane carrier is used as a bio-based material and main filler, and is the main attachment and growth site of microorganisms. The suitable structure and nutrients of this layer promote the growth and metabolism of microorganisms such as polyphosphate bacteria, reducing bacteria, and various anaerobic and aerobic bacteria, and remove nitrogen and phosphorus pollutants, phenols, hydrocarbons, alcohol pollutants, lead (Pb 2+ ), cadmium (Cd 2+ ), mercury (Hg 2+ ) and other heavy metal pollutants into harmless substances, achieving deep pollution removal.

[0070] Example 2

[0071] The reed straws treated by step 4 in the above embodiment 1 are woven into a grille by taking two reed straws and placing them in parallel as the "warp" of the grille. Next, another reed straw is taken and passed through from below the two "warp" reed straws in a direction perpendicular to the first two (as the "weft"), and then passed through from above the intersection of the two "warp" reed straws, and tightened to complete the first cross-weaving point. In this way, "weft" reed straws are continuously added, and the tightness of each intersection is maintained during the weaving process, so that the reed straws are fixed to each other and woven into a reed grille with a certain width and length.

[0072] According to the size of the sewage treatment plant inlet or the part that needs to be filtered, multiple such grilles are woven, then spliced ​​together and fixed in the appropriate position of the sewage treatment plant to play the role of physical support, buffering and uniform water distribution.

[0073] like Figure 1 As shown, the sewage treatment system using biofilm carrier:

[0074] Sewage enters treatment chamber 1 of the sewage treatment system from the water inlet pipe 1. A reed straw grille 3 is provided in treatment chamber 1. The reed straw grille divides treatment chamber 1 into two chambers, namely chamber 1 and chamber 2. Sewage first enters chamber 1, and enters chamber 2 after being filtered by the reed straw grille. A water pipe leading to treatment chamber 2 is provided in chamber 2, and the water in chamber 2 enters the top of treatment chamber 2 through the outlet pipe. A reed straw grille is provided above treatment chamber 2. The reed straw grille is provided in a V-shaped arrangement, which is referred to as a reed straw V-shaped net 4 here. An aeration pipe 7 is provided in treatment chamber 2 below the reed straw V-shaped net. The two ends of the aeration pipe are connected to the air inlet pipe 5 and the air outlet pipe 6 respectively, and the air outlet pipe is connected to the explosion main pipe 14 located in treatment chamber 3. An explosion fan 8 is provided on the side wall of the treatment chamber below the reed straw V-shaped net, and a stirring shaft 9 is provided on the bottom wall of treatment chamber 2 below the aeration pipe 7, and a stirring blade 10 is provided on the stirring shaft. A guide plate 11 is provided between the inner bottom wall and the side wall of the second processing chamber.

[0075] Treatment chamber 2 is connected to treatment chamber 3 through a connecting water pipe 12. Treatment chamber 3 is provided with a biofilm carrier 16 prepared in Example 1. An aeration head 15 is provided on the top of the biofilm carrier. The biofilm carrier 16 and the aeration head 15 together constitute the sewage treatment unit 13 of treatment chamber 3. The aeration head is connected to the explosion main pipe 14, and the explosion main pipe 14 is connected to treatment chamber 4. Treatment chamber 4 is provided with multiple layers of reed straw mats 18 from top to bottom, and landscape plants 17 are provided on the top layer of reed straw mats. A water outlet 19 is provided at the bottom of treatment chamber 4.

[0076] A valve 2 is provided on the water inlet pipe, and the sewage flows through the reed straw grille 3 prepared above. By adjusting the valve opening, the rate at which the sewage enters the system can be accurately controlled to match the processing capacity of the subsequent treatment unit and maintain the stability of the operation of the entire sewage treatment system. For example, when the subsequent treatment unit is under maintenance or the processing capacity is temporarily reduced, the valve can be appropriately adjusted to reduce the amount of sewage entering.

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

[0078] The sewage from treatment chamber 1 enters treatment chamber 2 through the 4 reed straw V-shaped nets, and is rotated and stirred in treatment chamber 2 after aeration. When the sewage flows through the reed straw V-shaped net, the water flow will be divided into multiple small streams by the V-shaped net to prevent the solid particles in the sewage from continuing to settle in one direction.

[0079] After the aeration fan 8 is started, external air is sucked in, transmitted through the air inlet pipe 5, and the air is delivered to the aeration main pipe 14 through the air outlet pipe 6. The aeration main pipe 14 serves as an air distribution channel to evenly distribute the air to each aeration head 15, which enables the air to be dispersed into tiny bubbles and released into the sewage. This aeration process increases the dissolved oxygen concentration in the sewage, creates a favorable oxygen-rich environment for the subsequent aerobic microorganisms to decompose the organic pollutants in the sewage, and promotes the efficient conduct of aerobic biochemical reactions. At the same time, the stirring shaft 9 drives the stirring blades 10 to rotate and vigorously stir the sewage. On the one hand, stirring causes the bubbles generated by aeration to be evenly dispersed in the sewage, increasing the contact area between oxygen and sewage, thereby improving the oxygen transfer efficiency; on the other hand, stirring promotes the full mixing of sewage and microorganisms, ensuring that the microorganisms can fully contact the organic pollutants in the sewage.

[0080] The guide plate 11 guides the flow direction of sewage in this area. After the sewage flows out of treatment chamber two, it enters the sewage treatment unit 13 for main sewage treatment. The sewage treated by treatment chamber three is pumped into treatment chamber four, and passes through multiple layers of reed straw mats 18 from top to bottom to absorb the residual soluble pollutants. The 17 landscape plants planted on the reed mats not only add a natural beauty to the sewage treatment area, but their roots can absorb some nutrients in the sewage, such as nitrogen, phosphorus and other elements, when growing in the sewage. While deeply purifying the sewage, the nutrient salt content in the sewage is further reduced to prevent eutrophication of the water body, which helps to maintain the balance of the entire sewage treatment ecosystem. In this process, suspended solids and other substances in the sewage gradually settle, and the clear liquid is further separated.

[0081] Example 3

[0082] This embodiment uses a composite membrane carrier composed of rice straw and functional bacterial agent to treat domestic sewage. Domestic sewage has a high content of organic matter, nitrogen, phosphorus and suspended solids, and is suitable for using a composite membrane carrier prepared from straw whose main function is to provide a carbon source. Rice straw is rich in a large amount of organic matter and can be used as a carbon source for microorganisms during sewage treatment, promoting the growth and reproduction of microorganisms.

[0083] Fix the prepared straw grid, straw V-shaped net and straw composite membrane carrier in the SBR or MBBR reactor. Before placing the membrane carrier, fill the reactor with water, then slowly place the membrane carrier frame into the bottom of the reactor to ensure that the membrane carrier is completely immersed in the sewage and evenly distributed.

[0084] The operation mode is to feed water for 15 minutes, and the water flow rate is controlled at 5m 3 / h, so that the sewage slowly enters the reactor to avoid impact on the membrane carrier and microorganisms; aeration for 2h, aeration intensity of 10m 3 / h, aeration is carried out through a microporous aeration disk; stirring for 2h, the stirring speed is 60rpm, and a mechanical stirring device is used to make the substances in the sewage fully contact with the microorganisms on the surface of the membrane carrier; aeration for 2h; stirring for 2h; sedimentation for 2h, the sedimentation speed is controlled at 0.8m / h, and the solid particles in the treated sewage are precipitated to the bottom of the reactor for subsequent water discharge; water discharge for 15min, and the water discharge flow rate is controlled at 5m 3 / h, the treated supernatant is discharged from the reactor; it is left idle for 1.5h to allow the microorganisms to recover their activity in a relatively stable environment. Two cycles are run every day, and the treatment cycle is 20 days.

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

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

[0087] After treatment, it was calculated that the COD removal rate reached 85.33%, and the final content dropped to below 73.72 mg / L; the TP removal rate reached 90.13%, and the content dropped to below 0.86 mg / L; the TN removal rate reached 82.35%, and the content dropped to below 11.15 mg / L; NH4 + -N removal rate reached 97.07%, and the content dropped to below 1.17mg / L. The pollutant content in sewage was significantly reduced, and the water quality was significantly improved.

[0088] Similarly, when faced with wastewater with high organic matter content, such as food processing wastewater, it is possible to consider adding a certain amount of rice straw for composite treatment during actual operation.

[0089] Example 4

[0090] This embodiment uses a composite membrane carrier composed of reed straw and functional bacterial agent to treat wastewater containing a large amount of cellulose, lignin, and chemical additives, such as papermaking industrial wastewater. Reed straw has high mechanical strength and toughness, and can provide support for the membrane carrier.

[0091] The reed straw composite membrane carrier is loaded into a specially made suspended filler ball, each filler ball is filled with an appropriate amount of membrane carrier, and then the filler ball is put into the SBR or MBBR reactor. The filler ball is made of corrosion-resistant, high-strength plastic, and has many small holes on its surface with a pore size of about 0.5 cm. Before putting in the filler ball, first fill the reactor with water, and then slowly and evenly put the filler ball into the reactor so that it can be freely suspended in the reactor.

[0092] The operation mode is to feed water for 15 minutes, and the water flow rate is controlled at 4m 3 / h. Since the high concentration of toxic chemicals in papermaking industrial wastewater has an inhibitory effect on the growth of microorganisms, the flow rate must be strictly controlled during water inlet to avoid excessive impact on microorganisms; aeration for 2h, aeration intensity of 8m 3 / h, using perforated tube aeration to provide oxygen for microorganisms; stirring for 2h, stirring speed is 50rpm, so that the sewage and membrane carrier are fully in contact; aeration for 2h; stirring for 2h; sedimentation for 2h, sedimentation speed is 0.6m / h, so that solid particles are precipitated; water discharge for 15min, the water discharge flow rate is controlled at 4m 3 / h, discharge the treated sewage; leave it idle for 1.5h to allow the microorganisms to recover. Two cycles are run every day, and the treatment cycle is 20 days.

[0093] Treatment effect evaluation:

[0094] Before treatment, the BOD content of the paper industry wastewater was about 826.82 mg / L, the COD content was about 1536.51 mg / L, the heavy metal ion content (such as lead, mercury, cadmium, etc., measured by total heavy metal ion concentration) was about 5.11 mg / L, and the chloride content was about 1036.20 mg / L.

[0095] During the treatment process, water samples were collected regularly for testing. After treatment, it was calculated that the BOD removal rate reached 92.49%, and the content dropped to below 62.09 mg / L; the COD removal rate reached 91.24%, and the content dropped to below 134.60 mg / L; the heavy metal ion removal rate reached 96.93%, and the content dropped to below 0.16 mg / L; the chloride removal rate reached 85.45%, and the content dropped to below 150.77 mg / L. The pollutant content in the sewage was effectively reduced, alleviating the pollution to the environment.

[0096] It should be emphasized that the above embodiments all embody the same inventive concept, and the details of some embodiments may not be fully developed, but can be supplemented by referring to the contents of other embodiments.

[0097] It should be understood that the parts not described in detail in the present invention belong to the prior art. The above combined with the accompanying drawings are only the specific implementation methods and processes of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the art should understand that this is only an example, and various changes and substitutions can be made to this implementation method without departing from the essence of the present invention. The scope of the present invention is limited only by the attached claims.

Claims

1. A method for constructing a biofilm carrier based on aquatic plant straw, characterized in that: The following steps are involved: Step 1, preparing a functional bacterial agent; Step 2, pre-treating aquatic plant straw; Step 3, preparing a polymer substrate; Step 4, diluting the functional bacterial agent in step 1 into a functional bacterial agent soaking solution, and soaking the aquatic plant straw pretreated in step 2 in the functional bacterial agent soaking solution; Step 5, taking out the soaked aquatic plant straws, weaving them into multi-layer regular polygons, and placing them on the polymer substrate of step 3.

2. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that: The functional bacterial agent in step 1 is a mixed bacteria of pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria, and the pretreated nitrifying bacteria, denitrifying bacteria and acetic acid bacteria are mixed in a mass ratio of 4:3:

3.

3. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 2, characterized in that: The functional bacterial agent mixing step in step 1 is: first, mix the pretreated nitrifying bacteria and denitrifying bacteria at a stirring speed of 100 rpm, and stir for 15 minutes; after the mixed bacterial activity of the nitrifying bacteria and denitrifying bacteria is stable, add the pretreated acetic acid bacteria and continue stirring for 10 minutes; store the mixed bacterial agent in a high-precision refrigerator at 4°C.

4. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that: The pretreatment method for aquatic plant straw with low fracture toughness in step 2 is: remove excess stems and leaves, clean the surface with distilled water and cut into 10-20 cm strips; soak in a sodium hydroxide solvent with a concentration of about 5%, wash with distilled water until there is no residue after being fully infiltrated, and finally dry.

5. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that: The pretreatment method for aquatic plant straw with high fracture toughness in step 2 is: remove excess stems and leaves, clean the surface with distilled water and cut into 10-20 cm long strips; soak in a polyvinyl alcohol solution with a concentration of about 10%, after being fully infiltrated, wash with distilled water until there is no residue, and finally air-dry.

6. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that: Step 3: The process of making the polymer substrate is: select a polyethersulfone or polyamide sheet, clean it and cut it into a circular substrate with a radius of 10 mm and a thickness of 8-12 mm; and there is a regular polygonal groove on the upper and lower surfaces of the circular substrate.

7. The method for constructing a biofilm carrier based on aquatic plant straw according to claim 1, characterized in that: The specific method of soaking the pretreated aquatic plant straw in step 4 is: The functional bacterial agent in step 1 is diluted with distilled water in a glass container at a ratio of 1:10 to obtain a functional bacterial agent soaking solution; the pretreated straw is placed in the functional bacterial agent soaking solution to ensure that all the straw is covered by the soaking solution, and the temperature is maintained at 25-30°C. During the soaking process, the soaking solution is stirred at a frequency of once every 10-15 minutes to ensure that the bacterial agent is evenly penetrated into the straw, and the soaking time is 30 minutes to 1 hour. After the soaking is completed, the straw is carefully removed from the soaking solution, placed in a well-ventilated and cool place, and dried for 24-48 hours.

8. A biofilm carrier, characterized in that: The method is constructed by any one of claims 1 to 7.

9. A sewage treatment system using a biofilm carrier, characterized in that: The invention comprises a horizontal box body, which is divided into four treatment chambers. The side wall of treatment chamber one is provided with a water inlet pipe, and the bottom wall of treatment chamber four is provided with a water outlet pipe. Sewage enters treatment chamber one of the sewage treatment system from the water inlet pipe. Treatment chamber one is provided with a straw grille, and the straw grille divides treatment chamber one into two chambers, namely chamber one and chamber two. Sewage first enters chamber one, and enters chamber two after being filtered by the straw grille. Chamber two is provided with a water pipe leading to treatment chamber two, and water in chamber two enters the upper part of treatment chamber two through the water outlet pipe. A straw grille is arranged above the second processing chamber, and the straw grille is arranged in a V shape, which is called a straw V-shaped net. A stirring shaft is arranged on the inner bottom wall of the second processing chamber below the straw V-shaped net, and a stirring blade is arranged on the stirring shaft; Treatment chamber two and treatment chamber three are connected by a connecting water pipe, and a biofilm carrier is arranged in treatment chamber three; treatment chamber four is provided with multiple layers of straw mats from top to bottom, and landscape plants are arranged on the top layer of straw mats.

10. A sewage treatment system using a biofilm carrier according to claim 9, characterized in that: An aeration pipe is arranged in the treatment chamber two below the straw V-shaped net, and the two ends of the aeration pipe are respectively connected to the air inlet pipe and the air outlet pipe; an aeration main pipe is arranged in the treatment chamber three, and the air outlet pipe is connected to the aeration main pipe; an aeration fan is arranged on the side wall of the treatment chamber below the straw V-shaped net, and an aeration head is arranged on the top of the biofilm carrier, and the biofilm carrier and the aeration head together constitute the sewage treatment unit of the treatment chamber three; the aeration head is connected to the aeration main pipe, and the aeration main pipe is connected to the treatment chamber four.

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