A rural domestic sewage treatment process based on bio-trickling-nanometer confinement

Abstract

The present application relates to the technical field of rural domestic sewage treatment, and particularly relates to a rural domestic sewage treatment process based on biological trickling-nano confinement, which mainly comprises the following steps: preparing nano confinement type biological filler, biological filler biofilm formation, start-up debugging, and biological filler regeneration and phosphorus collection; in view of the problem of excessive phosphorus content in tail water in the current rural domestic sewage treatment process, the process solves the problem of excessive phosphorus content in tail water discharged by the existing sewage equipment through a three-dimensional treatment method (nano confinement type filler design, muffled exposure biofilm optimization and intermittent water distribution strategy) combined with the existing equipment, realizes efficient removal and resource recovery of phosphorus; and the biological filler designed in the present application further improves the phosphorus removal effect by using the confinement La(OH)3, and also uses the interpenetrating network and microporous structure in the biological filler to lock a large amount of water, so that the normal growth of microorganisms during intermittent water distribution can be met, and the present application is more suitable for the needs of rural decentralized sewage treatment.

Description

Technical Field

[0001] This invention relates to the field of phosphorus-containing wastewater treatment technology, specifically to a rural domestic wastewater treatment process based on bio-trickling filtration and nano-confined filtration. Background Technology

[0002] In my country, most rural sewage treatment processes directly adopt those commonly used in urban sewage treatment without considering the unique climatic conditions and surrounding sewage quality of the rural areas. This has led to numerous new problems for many existing rural sewage treatment facilities, such as low operating rates and high maintenance costs.

[0003] To address the aforementioned issues, the inventors' team designed a zero-energy rural domestic sewage treatment device (CN118545838A). This device integrates the water path of the water pipe and the air path of the U-shaped aeration pipe. By using the negative pressure generated by natural wind, external air is forced into the U-shaped aeration pipe through the air inlet pipe for aeration, achieving zero-powered ventilation and oxygenation. This solves the problem of high operating costs in existing rural domestic sewage treatment methods.

[0004] However, during the follow-up investigation of the above-mentioned project, the inventors' team discovered that although the above-mentioned device can effectively degrade organic matter in rural sewage, the effluent at the end of the treatment still contains a large amount of phosphorus pollutants, that is, the phosphorus enrichment capacity at the end of the above-mentioned device is poor. To address this, the team designed an integrated device for low-carbon treatment and phosphorus recovery of rural domestic sewage based on the concept of nano-confinence, which provides the adsorption function of phosphorus enrichment in the effluent.

[0005] Following the above approach, as the research team further accumulated practical application performance data on nano-confined biological packing materials, and on this basis optimized the preparation process of the biological packing materials and the supporting equipment processing technology, the entire process could better solve the problem of phosphorus recovery in rural domestic sewage, and finally obtained the complete solution in this invention: a rural domestic sewage treatment process based on bio-trickling filtration-nano-confined filtration. Summary of the Invention

[0006] To address the aforementioned problems, this invention provides a rural domestic sewage treatment process based on bio-trickling filtration and nano-confined filtration.

[0007] S1. Preparation of nano-confined biological fillers: During the crosslinking reaction between the modified PVA gel and the crosslinking agent, a lanthanum-containing molecular sieve to improve phosphorus adsorption performance and an LDH dispersion to improve the structural strength of the material were added. After the reaction, a nano-confined biological filler was obtained. S2, Biofilm formation on biological packing material: First, the biological packing material prepared in S1 is laid into the biological trickling filter device located downstream of the process. Then, the phosphorus-containing tailwater of rural domestic sewage after anaerobic-aerobic treatment is collected, and the phosphorus-containing tailwater is screened and introduced into the pretreatment tank located upstream of the process. Finally, the biological packing material is attached to the biofilm by the aeration method. S3. Start debugging: During S2 operation, when the biofilm coverage area on the surface of the biological packing material reaches 50-70%, the process enters the commissioning phase: the commissioning period is 25 days, during which the hydraulic load is adjusted and compounded. The pH of the phosphorus-containing wastewater was adjusted to 6.5~7.2 using the following method; S4. Regeneration of biological packing material and phosphorus collection: S4-1. After the commissioning in S3 is completed, set the water distribution cycle based on the actual sewage discharge time in rural areas, introduce phosphorus-containing tailwater from the pretreatment tank into the biological trickling filter and run the device. After running for the set time, remove the phosphorus-containing biological packing. S4-2. Place the phosphorus-containing biological packing material from S4-1 into the regeneration solution. After vibration desorption, the regenerated biological packing material and phosphorus-containing solution are obtained. Collect the phosphorus-containing solution to complete the phosphorus resource recovery.

[0008] Furthermore, the steps of the simmering exposure method in S2 are as follows: S2-1. After the pretreatment tank is filled with phosphorus-containing tailwater, it is subjected to sluggish aeration, with the aeration intensity set to 0.2~0.5 m. 3 / (m 2 (·min), to maintain the dissolved oxygen concentration at 4~6 mg / L; S2-2, Maintain the parameters in S2-1 for 7 days, stop aeration and let it settle for 1~1.5 hours, then input 1 / 5 of the upper layer wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full. S2-3: Maintain the parameters in S2-1 for 6 days, stop aeration and let it settle for 1~1.5 hours, then input 1 / 4 of the upper layer of wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full; S2-4. Maintain the parameters in S2-1 for 5 days, stop aeration and let it settle for 1~1.5 hours. Then, input 1 / 3 of the upper wastewater in the pretreatment tank into the biological trickling filter and finally add phosphorus-containing tailwater until the pretreatment tank is full.

[0009] Furthermore, the regenerated solution in S4-2 is a NaOH solution with a concentration of 0.1~0.3 mol / L; the parameters for vibration desorption are: the rotational speed of the vibrating rotor is 180~200 r / min, and the desorption temperature is 50~65℃.

[0010] As another aspect of the present invention, a method for preparing nano-confined biological fillers is also provided: S1-1, Preparation of LDH dispersion: LDH supplement is prepared by ion exchange and dispersed in formamide to obtain LDH dispersion; S1-2, Preparation of modified PVA gel: Heating a polyvinyl alcohol solution at 90°C and adding activated carbon and sodium alginate to obtain a modified PVA gel; S1-3. Preparation of crosslinking agent: Add calcium chloride to polyvinyl alcohol solution and mix evenly to obtain crosslinking agent; S1-4. Preparation of lanthanum-containing molecular sieves: Y-type molecular sieves are added to lanthanum chloride solution to obtain lanthanum-containing molecular sieves; S1-5, Crosslinking and Curing: The modified PVA gel prepared in S1-2 is mixed with the crosslinking agent prepared in S1-3. While stirring, the lanthanum-containing molecular sieve prepared in S1-4 is added, followed by the LDH dispersion prepared in S1-1. After stirring for 2 hours, spherical products are precipitated. The spherical products are filtered out and washed with ultrapure water. Then, they are dried at 70~80℃ for 5 hours to obtain nano-confined biological fillers. Let n be the multiplier and The amount of modified PVA gel added is [60n, 65n] mL, the amount of crosslinking agent added is [200n, 205n] mL, the amount of lanthanum-containing molecular sieve added is [7n, 8n] g, and the amount of PVA dispersion added is [60n, 65n] mL.

[0011] Explanation: This invention utilizes a constructed directional confined space to promote the reverse conversion of stable LaPO4 to La(OH)3 through the confinement effect. The La(OH)3 confined within the host exhibits higher and more stable phosphorus removal efficiency. By introducing LDH supplementary material as a strength-enhancing unit into PVA, a honeycomb composite structure is constructed, improving the overall low mechanical strength of PVA as a bio-trickling filter filler. The nano-confined bio-filler constructed in this invention has an interpenetrating network and numerous micropores, thus improving stability during granulation while maintaining basic porosity.

[0012] As another aspect of the present invention, a bio-trickling filtration device is also provided: The biological trickling filter includes a hollow rectangular shell, whose inner cavity is divided from top to bottom into a water distribution layer, a primary packing layer, a secondary packing layer, a tertiary packing layer, and a water collection tank. Water deflectors are horizontally installed between the water distribution layer and the primary packing layer, between the primary packing layer and the secondary packing layer, and between the secondary packing layer and the tertiary packing layer. A ventilation duct is provided on the side wall of the casing above the splash plate, and the end of the ventilation duct is connected to a non-powered fan; The shell has a main outlet at the bottom of the side wall of the water collection tank, and a second return port is provided in a T-shape on the pipe connected to the main outlet; A water distributor connected to a manifold is installed at the top of the water distribution layer. The manifold includes an inlet, an outlet, and a first return port. The inlet is connected to the outlet of the pretreatment tank via a first peristaltic pump, the outlet is connected to the water distributor, and the first return port is connected to the second return port via a second peristaltic pump.

[0013] Furthermore, an upward-facing air outlet is provided at the end of the ventilation duct opposite to the position of the non-powered fan, and the upward-facing air outlet is equipped with a baffle.

[0014] Note: A non-powered fan can generate airflow in the inner cavity of the bio-trickling filter, increasing the oxygen exchange rate inside and outside the bio-bottom filter. Considering that this bio-trickling filter is used in rural areas, using electricity or other forms to drive ventilation would result in excessively high installation and maintenance costs, which does not meet the project requirements. Therefore, a non-powered fan was designed as the oxygen supply power source.

[0015] Furthermore, the heights of the secondary and tertiary packing layers are both half the height of the primary packing layer; The primary packing layer consists of a mixture of biological packing and ceramic particles, with a mass ratio of 3 to 4:1. The secondary packing layer consists of a mixture of biological packing and anthracite, with a mass ratio of 2~2.5:1. The primary packing layer contains a mixture of biological packing and polyurethane foam, with a mass ratio of 1 to 1.5:1.

[0016] Note: To balance the smooth descent of phosphorus-containing influent and microbial biofilm formation in the bio-trickling filter, the heights of the primary, secondary, and tertiary packing layers should be designed to minimize, moderate, and maximize resistance to the liquid flow. Therefore, the primary packing layer uses ceramic particles with the largest particle size mixed with the biological packing. In the secondary and tertiary packing layers, the particle size of the anthracite and polyurethane sponge gradually decreases, thus increasing water retention capacity. It is worth noting that the primary packing layer, designed for low water retention, is unfavorable for microbial biofilm formation. Therefore, to balance biofilm formation efficiency, the proportion of the biological packing with the best biofilm formation capacity in the primary packing layer should be maximized, ensuring that both water retention and biofilm formation meet design requirements. Furthermore, this mixed addition method further reduces the amount of the most expensive biological packing, thereby lowering the overall process cost.

[0017] Furthermore, each of the primary, secondary, and tertiary packing layers is equipped with a packing box that matches its height, and the packing box is slidably mounted on the roller support.

[0018] Note: The design of the roller support frame facilitates the pushing and pulling of the filling box, making it easy for personnel to operate.

[0019] Furthermore, the splash plate includes equally spaced gratings, each grating having an angle of 45° with the horizontal plane.

[0020] Note: Due to the ventilation effect of the ventilation duct, the phosphorus-containing water falling from the packing area does not fall vertically, but deviates with the wind direction. At this time, the angle of the grid on the splash plate should be adjusted to ensure that its plane is perpendicular to the falling direction of the droplets as much as possible, so as to enhance the breaking effect and thus increase the oxygen content in the droplets.

[0021] Compared with existing phosphorus-containing wastewater treatment processes, the beneficial effects of this invention are: (1) In response to the problem of excessive phosphorus content in the effluent of current rural domestic sewage treatment equipment, this invention designs a rural domestic sewage treatment process based on biological trickling filtration and nano-confined filtration. This process solves the problem of excessive phosphorus in the effluent of existing sewage equipment by using a three-dimensional treatment method combined with existing equipment (nano-confined packing design, suffocation and biofilm optimization, and intermittent water distribution strategy). It achieves efficient removal of phosphorus (TP>90%) and resource recovery (recovery rate>85%). Its core advantages are: 1) The process is compatible with the water quality characteristics of intermittent rural sewage discharge, low COD and high TP in the effluent of existing equipment; 2) The process has low energy consumption and the biological packing has a high regeneration rate, which can effectively reduce operation and maintenance costs; 3) The phosphorus recovery products can be directly used in agriculture to form a closed loop, providing an efficient, low-cost and sustainable technical path for rural sewage treatment and meeting the process iteration needs of existing rural decentralized sewage treatment stations.

[0022] (2) This invention not only designed a rural domestic sewage treatment process based on bio-trickling filter-nano confinement, but also designed a bio-trickling filter device to be used with it. The bio-trickling filter device uses a non-powered blower as an aeration oxygen source, and at the same time designed a splash plate that is perpendicular to the falling direction of the inclined falling phosphorus-containing droplets, which further increases the degree of breaking and aeration of the phosphorus-containing droplets, so that microorganisms can attach and grow better. Attached Figure Description

[0023] Figure 1 This is a flowchart of the rural domestic sewage treatment process of the present invention; Figure 2 This is an external view of the bio-trickling filtration device of the present invention; Figure 3 This is a cross-sectional view of the bio-trickling filtration device of the present invention; Figure 4 This is a partially enlarged cross-sectional view of point A in the biological trickling filter device; In the picture: 1-Shell, 11-Ventilation duct, 12-Non-powered fan, 13-Upward air outlet, 131-Shielding plate, 2-Water distribution layer, 21-Water distributor, 22-Combination pipe, 221-Water inlet, 222-Water outlet, 223-First return port, 23-First peristaltic pump, 3-First-stage packing layer, 4-Second-stage packing layer, 5-Third-stage packing layer, 6-Water collection tank, 61-Main outlet, 62-Second return port, 63-Second peristaltic pump, 7-Splash plate, 8-Packing box, 81-Roller support frame, 9-Pretreatment tank. Detailed Implementation

[0024] To further illustrate the methods and effects of this invention, the technical solution of this invention will be clearly and completely described below in conjunction with experiments.

[0025] Example 1: This example describes a bio-trickling filter device used in a bio-trickling filtration process for treating phosphorus-containing wastewater in rural areas.

[0026] See Figures 2-4 The biological trickling filter device designed in this invention includes a hollow rectangular shell 1, whose inner cavity is divided into a water distribution layer 2, a primary packing layer 3, a secondary packing layer 4, a tertiary packing layer 5 and a water collection tank 6 from top to bottom. Water deflectors 7 are horizontally installed between water distribution layer 2 and primary packing layer 3, between primary packing layer 3 and secondary packing layer 4, and between secondary packing layer 4 and tertiary packing layer 5. A ventilation pipe 11 is provided on the side wall of the housing 1 above the splash plate 7, and the end of the ventilation pipe 11 is connected to the non-powered fan 12. The shell 1 has a main outlet 61 at the bottom of the side wall of the water collection tank 6, and a second return port 62 is provided in a T-shape on the pipe connected to the main outlet 61. The top of the water distribution layer 2 is provided with a water distributor 21 connected to the manifold 22. The manifold 22 includes an inlet 221, an outlet 222 and a first return port 223. The inlet 221 is connected to the tail end of the anaerobic-aerobic process via a first peristaltic pump 23, the outlet 222 is connected to the water distributor 21, and the first return port 223 is connected to the second return port 62 via a second peristaltic pump 63.

[0027] Specifically, an upward-facing air outlet 13 is provided at the end of the ventilation pipe 11 opposite to the position of the non-powered fan 12, and the upward-facing air outlet 13 is provided with a baffle 131.

[0028] Specifically, the heights of the secondary packing layer 4 and the tertiary packing layer 5 are both half the height of the primary packing layer 3; Among them, the filler in the primary filler layer 3 is a mixture of biological filler and ceramic particles, with a mass ratio of 3:1. The filler in the secondary filler layer 4 is a mixture of biological filler and anthracite, with a mass ratio of 2:1. The filler in the primary filler layer 3 is a mixture of biological filler and polyurethane sponge, with a mass ratio of 1:1.

[0029] Specifically, each of the primary packing layer 3, the secondary packing layer 4, and the tertiary packing layer 5 is provided with a packing box 8 that matches its height, and the packing box 8 is slidably mounted on the roller support 81.

[0030] Specifically, the splash plate 7 includes equally spaced grid strips 71, each grid strip 71 having an angle of 45° with the horizontal plane.

[0031] Example 2: This example describes a bio-trickling filtration device with different parameters, which differs from the bio-trickling filtration device in Example 1 only in the following aspects: The filler in the primary filler layer 3 is a mixture of biological filler and ceramic particles, with a mass ratio of 4:1. The filler in the secondary filler layer 4 is a mixture of biological filler and anthracite, with a mass ratio of 2.5:1. The filler in the primary filler layer 3 is a mixture of biological filler and polyurethane sponge, with a mass ratio of 1.5:1. Example 3: This example describes a rural domestic sewage treatment process based on the biological trickling filter device in Example 1.

[0032] S1. Preparation of nano-confined biological fillers: During the crosslinking reaction between the modified PVA gel and the crosslinking agent, a lanthanum-containing molecular sieve to improve phosphorus adsorption performance and an LDH dispersion to improve the structural strength of the material were added. After the reaction, a nano-confined biological filler was obtained. S2, Biofilm formation on biological packing material: First, the biological packing material prepared in S1 is laid into a bio-trickling filter device located downstream of the process. Then, phosphorus-containing wastewater from rural domestic sewage treated by an anaerobic-aerobic process is collected, and the phosphorus-containing wastewater is passed through a screen and introduced into a pretreatment tank 9 located upstream of the process. Finally, biofilm formation on the biological packing material is achieved through aeration. S2-1. After the pretreatment tank is filled with phosphorus-containing tailwater, it is subjected to sluggish aeration, with the aeration intensity set at 0.2 m. 3 / (m 2 (·min), to maintain the dissolved oxygen concentration at 4 mg / L; S2-2, maintain the parameters in S2-1 for 7 days, stop aeration and let it settle for 1 hour, then input 1 / 5 of the upper wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full. S2-3, Maintain the parameters in S2-1 for 6 days, stop aeration and let it settle for 1 hour, then input 1 / 4 of the upper layer wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full; S2-4. Maintain the parameters in S2-1 for 5 days, stop aeration and let it settle for 1 hour, then input 1 / 3 of the upper wastewater in the pretreatment tank into the biological trickling filter and finally add phosphorus-containing tailwater until the pretreatment tank is full. S3. Start debugging: During the S2 operation, when the biofilm coverage area on the surface of the biological packing reaches 50%, the process enters the commissioning phase: the commissioning period is 25 days, during which the hydraulic load is adjusted and compounded. The pH of the phosphorus-containing wastewater was adjusted to 6.5 using this method; S4. Regeneration of biological packing material and phosphorus collection: S4-1. After the commissioning in S3 is completed, set the water distribution cycle based on the actual sewage discharge time in rural areas, introduce phosphorus-containing tailwater from the pretreatment tank into the biological trickling filter and run the device. After running for the set time, remove the phosphorus-containing biological packing. S4-2. The phosphorus-coated biological packing material described in S4-1 is placed in a 0.1 mol / L NaOH solution. Under the conditions of a vibrating rotor speed of 180 r / min and a desorption temperature of 50℃, the regenerated biological packing material and phosphorus-containing solution are obtained after vibration desorption. The phosphorus-containing solution is collected to complete the phosphorus resource recovery.

[0033] Example 4: The description in this example is based on the content of Example 3, which is a rural domestic sewage treatment process under another parameter.

[0034] S1. Preparation of nano-confined biological fillers: During the crosslinking reaction between the modified PVA gel and the crosslinking agent, a lanthanum-containing molecular sieve to improve phosphorus adsorption performance and an LDH dispersion to improve the structural strength of the material were added. After the reaction, a nano-confined biological filler was obtained. S2, Biofilm formation on biological packing material: First, the biological packing material prepared in S1 is laid into a bio-trickling filter device located downstream of the process. Then, phosphorus-containing wastewater from rural domestic sewage treated by an anaerobic-aerobic process is collected, and the phosphorus-containing wastewater is passed through a screen and introduced into a pretreatment tank 9 located upstream of the process. Finally, biofilm formation on the biological packing material is achieved through aeration. S2-1. After the pretreatment tank is filled with phosphorus-containing tailwater, it is subjected to sluggish aeration, with the aeration intensity set at 0.5 m. 3 / (m 2 •min), to maintain the dissolved oxygen concentration at 6 mg / L; S2-2, maintain the parameters in S2-1 for 7 days, stop aeration and let it settle for 1.5 hours, then input 1 / 5 of the upper layer wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full. S2-3: Maintain the parameters in S2-1 for 6 days, stop aeration and let it settle for 1.5 hours, then input 1 / 4 of the upper layer wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full; S2-4. Maintain the parameters in S2-1 for 5 days, stop aeration and let it settle for 1.5 hours, then input 1 / 3 of the upper wastewater in the pretreatment tank into the biological trickling filter and finally add phosphorus-containing tailwater until the pretreatment tank is full. S3. Start debugging: During the S2 operation, when the biofilm coverage area on the surface of the biological packing reaches 70%, the process enters the commissioning phase: the commissioning period is 25 days, during which the hydraulic load is adjusted and compounded. The pH of the phosphorus-containing wastewater was adjusted to 7.2 using this method; S4. Regeneration of biological packing material and phosphorus collection: S4-1. After the commissioning in S3 is completed, set the water distribution cycle based on the actual sewage discharge time in rural areas, introduce phosphorus-containing tailwater from the pretreatment tank into the biological trickling filter and run the device. After running for the set time, remove the phosphorus-containing biological packing. S4-2. The phosphorus-coated biological packing material described in S4-1 is placed in a 0.3 mol / L NaOH solution. Under the conditions of a vibrating rotor speed of 200 r / min and a desorption temperature of 65℃, the regenerated biological packing material and phosphorus-containing solution are obtained after vibration desorption. The phosphorus-containing solution is collected to complete the phosphorus resource recovery.

[0035] Example 5: This example describes a specific preparation method for a biological packing material.

[0036] S1-1. Preparation of LDH supplement material by ion exchange method; S1-1-1, Precursor Preparation: Add 0.1 g of MgAl-LDH-CO3 powder and 15 g of sodium nitrate to 200 mL of deionized water, then adjust the pH to 4.0 with 0.1 mol / L dilute nitric acid, and sonicate at 200 W for 5 min. S1-1-2, Ion exchange: Under N2 protection, the mixture was allowed to stand for 24 h, and then shaken to disperse it every 2 h. After being filtered at normal pressure, it was dried at 50℃ and vacuum degree of -0.08 MPa for 24 h, and then ground to obtain MgAl-LDH-NO3 powder with a particle size of 100 μm. S1-1-3, LDH stripping: 0.45 g MgAl-LDH-NO3 was prepared according to the above method and dispersed in 60 ml formamide. The mixture was magnetically stirred at 50 °C for 72 h to obtain a dispersion of LDH supplement. S1-2, Preparation of modified PVA materials: S1-2-1, Preparation of gel solution: Prepare a 50 mL polyvinyl alcohol solution with a mass fraction of 8 wt.%, heat it at 90℃ to dissolve it, then add 3 g activated carbon and 4 g sodium alginate, and stir continuously until a uniform gel solution is obtained for later use. S1-2-2, Preparation of Lanthanum-Containing Molecular Sieves: S1-2-2-1, Preparation of La 3+ A 0.4% lanthanum chloride solution was prepared, and the pH was adjusted to 10 with a 2 mol / L NaOH solution. S1-2-2-2: Add Y-type molecular sieve to the lanthanum chloride solution in S1-3-1 at a solid-liquid ratio of 1:45 to obtain a mixed solution, and then shake it in a constant temperature water bath shaker at 25℃ for 15 h. S1-2-2-3: Filter the mixture after shaking treatment in S1-2-2-2 to obtain a filter cake. Wash the filter cake three times and then dry it at 70℃ for 5 h to obtain a lanthanum-containing molecular sieve. S1-2-3, Prepare the crosslinking agent: Prepare a 200 mL polyvinyl alcohol solution with a mass fraction of 4 wt.%, then add 3 mg of calcium chloride and mix well to obtain a crosslinking agent; S1-2-4, Cross-linking and curing: The gel solution prepared in S1-2-1 was mixed with the crosslinking agent prepared in S1-2-3. While stirring, 7 g of the lanthanum-containing molecular sieve prepared in S1-2-2 was added, followed by the dispersion prepared in S1-1. After stirring for 1.5 h, spherical products precipitated. The spherical products were filtered out and washed with ultrapure water, and then dried at 70 °C for 5 h to obtain the modified PVA material, namely the nano-confined biotrickling filter media.

[0037] Example 6: The content of this example describes the preparation method of biological packing material under another parameter.

[0038] S1-1. Preparation of LDH supplement material by ion exchange method; S1-1-1, Precursor Preparation: Add 0.15 g of MgAl-LDH-CO3 powder and 18 g of sodium nitrate to 200 mL of deionized water, then adjust the pH to 4.0 with 0.1 mol / L dilute nitric acid, and sonicate at 300 W for 10 min. S1-1-2, Ion exchange: Under N2 protection, the mixture was allowed to stand for 24 h, and then shaken to disperse it every 2 h. After being filtered at normal pressure, it was dried at 60℃ and vacuum degree of -0.08 MPa for 24 h, and then ground to obtain MgAl-LDH-NO3 powder with a particle size of 120 μm. S1-1-3, LDH stripping: 0.45 g MgAl-LDH-NO3 was prepared according to the above method and dispersed in 54 ml formamide. The mixture was magnetically stirred at 60 °C for 72 h to obtain a dispersion of LDH supplement. S1-2, Preparation of modified PVA materials: S1-2-1, Preparation of gel solution: Prepare a 60 mL solution of polyvinyl alcohol with a mass fraction of 10 wt.%, heat it at 95℃ to dissolve it, then add 3.5 g of activated carbon and 4.5 g of sodium alginate, and stir continuously until a uniform gel solution is obtained for later use. S1-2-2, Preparation of Lanthanum-Containing Molecular Sieves: S1-2-2-1, Preparation of La 3+ A 0.6% lanthanum chloride solution was prepared, and the pH was adjusted to 10 with a 2.5 mol / L NaOH solution. S1-2-2-2: Add Y-type molecular sieve to the lanthanum chloride solution in S1-3-1 at a solid-liquid ratio of 1:50 to obtain a mixed solution, and then shake it in a constant temperature water bath shaker at 25℃ for 16 h. S1-2-2-3: Filter the mixture after shaking treatment in S1-2-2-2 to obtain a filter cake. Wash the filter cake 5 times and then dry it at 80℃ for 5 h to obtain a lanthanum-containing molecular sieve. S1-2-3, Prepare the crosslinking agent: Prepare a 200 mL solution of polyvinyl alcohol with a mass fraction of 5 wt.%, then add 3.5 mg of calcium chloride and mix well to obtain a crosslinking agent; S1-2-4, Cross-linking and curing: The gel solution prepared in S1-2-1 was mixed with the crosslinking agent prepared in S1-2-3. While stirring, 8 g of the lanthanum-containing molecular sieve prepared in S1-2-2 was added, followed by the dispersion prepared in S1-1. After stirring for 2 h, spherical products precipitated. The spherical products were filtered out and washed with ultrapure water, and then dried at 80 °C for 5 h to obtain the modified PVA material, a nano-confined biotrickling filter media.

[0039] Experimental Example: The description of this experimental example is based on the schemes described in Examples 3 and 5, and aims to illustrate the practical application effect of the present invention.

[0040] 1. Experimental Environment Laboratory simulated wastewater parameters: TP: 120 mg / L, pH: 8.

[0041] Intermittent water distribution strategy: Rural domestic sewage discharge is highly intermittent, concentrated in the morning, noon, and evening. When flow interruption occurs, the supply of nutrients to microorganisms is suspended, forcing them to maintain activity primarily through endogenous respiration. Once the system is reactivated, the microorganisms can again obtain a large amount of nutrients, thus significantly adsorbing and decomposing pollutants in the water. Based on these characteristics, an indirect water distribution strategy is designed as shown in Table 1: Table 1 Intermittent Water Distribution Strategy

[0042] Experimental equipment: The adsorption performance of the prepared biological packing material was tested in a laboratory environment. A separate adsorption column with a diameter of 5 cm and a height of 15 cm was designed as the test container. Filter plates were installed at both the upper and lower openings of the adsorption column. The power unit was a Lange peristaltic pump (BT100-1L, Longer Pump) to transfer sewage at a set flow rate.

[0043] 2. Phosphorus adsorption performance test of biological packing material The adsorption column was filled with 3 cm of biological packing material. Experimental wastewater was pumped into the adsorption column at a flow rate of 2.5 mL / min using a peristaltic pump. The initial phosphorus concentration of the wastewater was 120 mg / L. For every 30 mL of wastewater treated by the adsorption system, 2 mL of wastewater was collected for testing until the effluent phosphorus concentration (C) was reached. t ) is close to the phosphorus concentration (C0) in the wastewater influent, and when C t The system stops running when / C0=0.9. The experimental group is designed as follows: Experimental group: The nano-confined biotrickling filter media prepared in this invention: containing LDH supplement, lanthanum molecular sieve, and modified PVA gel; Control group 1: Pure PVA gel filler without LDH supplement and lanthanum-containing molecular sieve, containing only activated carbon and sodium alginate.

[0044] Control group 2: Commercially available ordinary biological packing material: activated carbon-zeolite packing material.

[0045] Table 2. Adsorption performance data of phosphorus by biological packing material

[0046] First, as can be seen from the data in Table 2, the total adsorption capacity of the biological packing material in the experimental group is much higher than that in the control groups 1 and 2. Moreover, the adsorption rate of phosphorus by the biological packing material in the experimental group is also much higher than that in the control groups 1 and 2 (for example, the removal rate of the experimental group in the initial stage (30 mL) reached 84.6%, which is significantly higher than that of the control groups (control group 1: 29.0%; control group 2: 39.3%).

[0047] The reason why the biological packing material in the experimental group performed better than that in the control group is that the layered dihydroxyl structure of the LDH supplement adsorbs through ion exchange. Lanthanum-containing molecular sieves and form Precipitation enhances chemical adsorption; the three-dimensional network structure of the modified PVA gel provides a nano-confinement effect, which can prolong the residence time of pollutants.

[0048] 3. Test on the phosphorus desorption performance of biological packing material In this experiment, since only the desorption performance of the biological packing material was tested, a mixed solution desorption method was adopted: After the bio-trickling filter tower had run for a set time, the biological packing material was removed and placed in a mixed solution of 100 mg / L KH₂PO₄ and 0.1 mol / L NaOH (200 mL). Desorption was carried out by vibration at 70℃ for 18 h. The solution was then filtered through a 0.45 µm membrane filter, and the phosphorus concentration was measured using a UV-Vis spectrophotometer. The desorption rate of the adsorbed packing material was calculated. The experimental design is as follows: Experimental group: the bio-filler of this invention after adsorption saturation, and after undergoing one adsorption-desorption cycle.

[0049] Control group 1: Unmodified ordinary PVA gel filler, with the same adsorption capacity as the experimental group.

[0050] Control group 2: Commercially available activated carbon-zeolite packing material, with the same adsorption capacity as the experimental group.

[0051] Table 3. Phosphorus Elucidation Performance Data of Biological Packing Material

[0052] First, as can be seen from the data in Table 3, the initial desorption rate of phosphorus by the biological packing material in the experimental group was as high as 92.5%, significantly better than that in the control group (≤74.6%). The core reason for this performance difference is that LDH releases phosphorus under alkaline high-temperature conditions (0.1 mol / L NaOH, 70℃). Lanthanum-containing molecular sieves pass through La 3+ OH - Competitive replacement release ; In addition, it can be seen that the cyclic stability of the biological packing material in the experimental group is much higher than that in the control group: after 5 cycles, the experimental group still maintains an 85.4% desorption rate and a residual adsorption capacity of 18.3 mg / g, indicating that the biological packing material has a stable structure.

[0053] The reason why the biological filler in the experimental group outperformed the biological filler in the control group is that ordinary PVA gel lacks ion exchange sites, physical adsorption is dominant, and the desorption rate is low; and commercially available fillers have rapid desorption performance decay due to pore blockage and irreversible chemical bonds.

Claims

1. A rural domestic sewage treatment process based on biotrickling filtration-nano confinement, characterized in that, Includes the following steps: S1. Preparation of nano-confined biological fillers: During the crosslinking reaction between the modified PVA gel and the crosslinking agent, a lanthanum-containing molecular sieve to improve phosphorus adsorption performance and an LDH dispersion to improve the structural strength of the material were added. After the reaction, a nano-confined biological filler was obtained. S2, Biofilm formation on biological packing material: First, the biological packing material prepared in S1 is laid into the biological trickling filter device located downstream of the process. Then, the phosphorus-containing tailwater of rural domestic sewage after anaerobic-aerobic process is collected, and the phosphorus-containing tailwater is screened and introduced into the pretreatment tank (9) located upstream of the process. Finally, the biological packing material is attached to the biofilm by the aeration method. S3. Start debugging: During S2 operation, when the biofilm coverage area on the surface of the biological packing material reaches 50-70%, the process enters the commissioning phase: the commissioning period is 25 days, during which the hydraulic load is adjusted and compounded. The pH of the phosphorus-containing wastewater was adjusted to 6.5~7.2 using the following method; S4. Regeneration of biological packing material and phosphorus collection: S4-1. After the commissioning in S3 is completed, set the water distribution cycle based on the actual sewage discharge time in rural areas, introduce phosphorus-containing tailwater from the pretreatment tank into the biological trickling filter and run the device. After running for the set time, remove the phosphorus-containing biological packing. S4-2. Place the phosphorus-coated biological packing material described in S4-1 into the regeneration solution, and obtain the regenerated biological packing material and phosphorus-containing solution after vibration desorption. Collect the phosphorus-containing solution to complete the phosphorus resource recovery.

2. The rural domestic sewage treatment process based on biotrickling filtration-nano confinement as described in claim 1, characterized in that, The steps of the simmering method described in S2 are as follows: S2-1. After the pretreatment tank is filled with phosphorus-containing tailwater, it is subjected to sluggish aeration, with the aeration intensity set to 0.2~0.5 m. 3 / (m 2 (·min), to maintain the dissolved oxygen concentration at 4~6 mg / L; S2-2, Maintain the parameters in S2-1 for 7 days, stop aeration and let it settle for 1~1.5 hours, then input 1 / 5 of the upper layer wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full. S2-3: Maintain the parameters in S2-1 for 6 days, stop aeration and let it settle for 1~1.5 hours, then input 1 / 4 of the upper layer of wastewater in the pretreatment tank into the biological trickling filter, and finally add phosphorus-containing tailwater until the pretreatment tank is full; S2-4. Maintain the parameters in S2-1 for 5 days, stop aeration and let it settle for 1~1.5 hours. Then, input 1 / 3 of the upper wastewater in the pretreatment tank into the biological trickling filter and finally add phosphorus-containing tailwater until the pretreatment tank is full.

3. The rural domestic sewage treatment process based on biotrickling filtration-nano confinement as described in claim 1, characterized in that, The regenerated solution in S4-2 is a NaOH solution with a concentration of 0.1~0.3 mol / L. The parameters for vibration desorption are: the rotation speed of the vibrating rotor is 180~200 r / min, and the desorption temperature is 50~65℃.

4. The rural domestic sewage treatment process based on biotrickling filtration-nano confinement as described in claim 1, characterized in that, The biological trickling filter includes a hollow rectangular shell (1), whose inner cavity is divided into a water distribution layer (2), a primary packing layer (3), a secondary packing layer (4), a tertiary packing layer (5), and a water collection tank (6) from top to bottom. Water splash plates (7) are horizontally arranged between the water distribution layer (2) and the primary packing layer (3), between the primary packing layer (3) and the secondary packing layer (4), and between the secondary packing layer (4) and the tertiary packing layer (5). The housing (1) has a ventilation pipe (11) on the side wall above the splash plate (7), and the end of the ventilation pipe (11) is connected to a non-powered fan (12). The shell (1) has a main outlet (61) at the bottom of the side wall of the water collection tank (6), and a second return port (62) is provided in a T-shape on the pipe connected to the main outlet (61). The top of the water distribution layer (2) is provided with a water distributor (21) connected to the confluence pipe (22). The confluence pipe (22) includes an inlet (221), an outlet (222), and a first return port (223). The inlet (221) is connected to the outlet of the pretreatment tank (9) via a first peristaltic pump (23), the outlet (222) is connected to the water distributor (21), and the first return port (223) is connected to the second return port (62) via a second peristaltic pump (63).

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