Hanging type light medium rapid biological filter for secondary sedimentation tank

Abstract

The utility model provides a suspension type light medium rapid biological filter for a secondary sedimentation tank, which belongs to the technical field of water treatment equipment, a plurality of suspension type light medium rapid biological filters which operate independently are arranged on the outer wall of the secondary sedimentation tank, the suspension type light medium rapid biological filter comprises a water inlet pipe and a water outlet pipe which are provided with independent valves, and a perforated baffle is arranged in the filter. A filter unit filter layer is arranged between the two perforated baffles; through holes are formed in the two perforated baffles, and the through holes in the top perforated baffle are used for blocking filter materials in the filter layers of the filter units. The lower end of the filter tank is inclined; a sludge discharge pipe is arranged on one side of the bottom of the filter in the inclined direction The filter materials are rearranged by regulating and controlling the water level and promoting friction among particles through inlet and outlet water so as to enlarge the effective thickness of the filter material layer. The filter layer not only can intercept suspended solids in effluent of the secondary sedimentation tank, but also can adsorb and convert pollutants by virtue of a biological membrane growing on the filter layer. An additional backwashing device and a backwashing water inlet pipe are not needed, and a supporting layer and gas-water backwashing equipment are not needed, so that the construction and operation cost is greatly reduced.

Description

Technical Field

[0001] The utility model belongs to the technical field of water treatment equipment, and in particular relates to a secondary sedimentation tank suspended light medium rapid biological filter. Background Art

[0002] Sewage treatment plants in my country generally use the activated sludge process as the core treatment unit, with secondary sedimentation tanks serving as the subsequent sludge-water separation unit. Sludge-water separation ensures both effluent clarity and provides return sludge for upstream processes, directly impacting the operational performance of the sewage treatment system. Radial flow sedimentation tanks are widely used due to their high treatment capacity and excellent sedimentation performance. However, with the increasing intensity of environmental remediation efforts in my country, radial flow sedimentation tanks designed and operated according to the Class A requirements of the "Pollutant Discharge Standard for Urban Wastewater Treatment Plants" are finding it difficult to meet the Quasi-Class IV requirements of the "Water Pollution Prevention and Control Action Plan." On the one hand, the residual sludge flocs and other solids carried in the effluent of radial flow sedimentation tanks are important carriers of organic matter, nitrogen, and phosphorus. Although increasing the recirculation ratio can to some extent solve the problem of floc formation difficulties caused by high microbial activity, it still cannot overcome the shear and fragmentation effect of the rising airflow on the flocs during the aeration process. In addition, a high recirculation ratio may destroy the anaerobic environment of the activated sludge, affecting the pollutant purification effect. On the other hand, the effluent of the secondary sedimentation tank also contains dissolved organic matter and nitrogen and phosphorus, which also need to be further removed to meet the quasi-Class IV standard. Biofiltration is a powerful supplement to the activated sludge method, which is not very effective in removing low-concentration dissolved pollutants. Therefore, the current process mainly uses filter cloth filters, coagulation sedimentation, membrane bioreactors, deep-bed denitrification filters, etc. at the back end of the secondary sedimentation tank to further intercept solids and remove soluble components to ensure the effluent water quality.

[0003] As my country's environmental remediation efforts steadily progress, their primary focus has shifted from meeting emission standards and controlling pollution to achieving economically efficient, clean, and low-carbon processes. Current processes achieve limited water quality improvements through high energy consumption and high costs, hindering carbon peak and carbon neutrality goals, failing to meet the development requirements and trends of environmental remediation efforts, and requiring significant land. Therefore, there is an urgent need to develop an economical, low-carbon, and intensive system for enhanced solids retention at the back end of radial flow sedimentation tanks. Utility Model Content

[0004] The utility model provides a secondary sedimentation tank suspended light medium rapid biological filter to solve the technical problems of poor pollutant purification effect, high energy consumption and high cost in the prior art.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A secondary sedimentation tank suspended lightweight medium rapid biological filter, multiple lightweight medium rapid lightweight biological filters are suspended on the outer wall of the secondary sedimentation tank, including a filter unit filter layer, the filter unit filter layer is arranged inside the filter tank, the upper end of the filter unit filter layer is fixedly installed with a top perforated baffle, the lower end of the filter unit filter layer is movably installed with a bottom perforated baffle, a filter unit water inlet pipe is arranged at the lower end of one side of the filter tank side wall, the filter unit water inlet pipe is connected to the secondary sedimentation tank, and a filter unit water outlet pipe is arranged at the upper end of the other side of the filter tank side wall.

[0007] The filter material in the filter layer of the filter unit is 0.02-0.05 g / cm 3 Spherical polystyrene foam beads with a particle size of 4-6mm.

[0008] The top perforated baffle is provided with perforations with a diameter of 3 mm.

[0009] The bottom perforated baffle is provided with perforations with a diameter of 3 mm.

[0010] The secondary sedimentation tank includes a secondary sedimentation tank outlet weir, and the filter unit water inlet pipe is connected to the secondary sedimentation tank outlet weir.

[0011] A filter unit water inlet pipe stop valve is provided on the filter unit water inlet pipe.

[0012] A filter unit outlet pipe stop valve is provided on the filter unit outlet pipe.

[0013] The lower end of the filter tank is tilted at an angle of 30-45 degrees.

[0014] A filter unit mud discharge pipe is installed on the inclined side of the lower end of the filter tank.

[0015] A filter unit mud discharge pipe stop valve is provided on the filter unit mud discharge pipe.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The utility model discloses a secondary sedimentation tank suspended lightweight medium rapid biological filter, which is directly suspended on the wall of the secondary sedimentation tank, rationally utilizing the space on the outer wall of the secondary sedimentation tank, and not occupying a large amount of additional land and other resources, thereby increasing the sewage treatment function within a limited space, which is of great significance for some sewage treatment facilities with limited space. Most components are made of lightweight materials, which are easy to transport and install. The modular design allows the equipment to be flexibly assembled and disassembled according to actual needs, reducing the equipment investment cost. During operation, since filtration and backwashing are achieved by relying on water flow as the driving force, no additional backwashing equipment is required, which greatly reduces the operating energy consumption and maintenance costs. In addition, for sewage treatment plants that have undergone process upgrades, the filter serves as a pretreatment unit for subsequent deep treatment, effectively reducing the amount of reagents and carbon sources added, further saving operating costs.

[0018] Furthermore, compared to traditional filter media, the filter layer of the filter unit of the present invention uses spherical polystyrene foam beads of a specific density and particle size as filter media. Polystyrene foam beads have the advantages of large specific surface area and high surface potential. They have more sites that are easier to adsorb solids and can provide a larger specific surface area, which is conducive to the attachment and growth of microorganisms, thereby enhancing the biodegradation of pollutants and improving the purification effect. Moreover, they produce elastic deformation after being squeezed, which can form dense pores and strengthen the speed separation caused by the narrow tube effect. On the basis of the traditional filter bed sedimentation, interception, inertia, diffusion, water flow dynamics and other mechanisms, they further adjust the local flow field to intercept solids, enriching the interception path. The filter layer intercepts and inoculates the residual sludge flocs in the effluent of the secondary sedimentation tank, enriching the surface of the filler with long-generation period, degradable microbial metabolites and other difficult-to-degrade organic matter and bacteria with strong denitrification ability, making up for the defect of insufficient retention capacity of low reflux ratio bacteria, further strengthening pollutant degradation, and improving effluent water quality.

[0019] Furthermore, the low-density filter media makes the entire filter unit lighter, facilitating installation and maintenance, reducing the structural strength requirements of the filter tank and indirectly lowering construction costs. It also reduces energy consumption during operation, for example, requiring less power for backwashing and other operations.

[0020] Furthermore, the 3mm diameter perforations on the top and bottom perforated baffles evenly distribute incoming sewage throughout the filter layer, ensuring that filter media in every area is fully exposed to the sewage, improving filtration efficiency and effectiveness. The perforations not only ensure the flow of water and air, but also effectively prevent filter media from escaping through the inlet and outlet, maintaining the stability of the filter layer and ensuring long-term, stable filtration performance.

[0021] Furthermore, the installation of check valves on the filter's inlet pipe and the filter unit's outlet pipe facilitates control of the light-weight biofilter's inflow and outflow, enabling flexible adjustments based on actual treatment needs and water quality. In the event of significant water quality fluctuations, the valves can be adjusted to control the wastewater's residence time in the filter, optimizing treatment effectiveness. In the event of equipment maintenance or failure, the valves can be closed promptly without impacting the normal operation of the secondary sedimentation tank and other equipment, improving the reliability and controllability of the entire sewage treatment system.

[0022] Furthermore, the lower end of the filter tank is tilted 30-45 degrees. By utilizing the effect of gravity, the sludge settled at the bottom of the filter tank can naturally slide down and gather on the tilted side, which is convenient for subsequent sludge discharge operations, avoids excessive accumulation of sludge in the filter tank and affects the filtration effect, further improves the sewage discharge effect, and also reduces the energy consumption and difficulty of sludge discharge.

[0023] Furthermore, the filter unit sludge discharge pipe, installed on the inclined side of the filter tank's lower end, combined with a stop valve, can regularly discharge accumulated sludge to ensure the normal operation of the filter tank. The stop valve prevents sludge backflow or sewage leakage during normal operation, ensuring safe and effective sludge discharge operations, maintaining good hydraulic conditions and microbial environment within the filter tank, and further improving pollutant purification effectiveness.

[0024] Furthermore, the several filter tanks on the outer wall of the secondary sedimentation tank are independent of each other. When one of them cannot operate due to backwashing, the other units can absorb the water volume of this unit by increasing the flow rate (i.e., increasing the processing capacity), breaking through the traditional two-stage operation and backwashing of the filter tank, and the entire set of equipment can perform uninterrupted filtration while running and backwashing. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 : Schematic diagram of the cross section of the suspended lightweight medium rapid lightweight biofilter in the secondary sedimentation tank;

[0026] Figure 2 : Schematic diagram of the connection of the suspended lightweight medium rapid lightweight biofilter in the secondary sedimentation tank;

[0027] Figure 3 : Schematic diagram of the secondary sedimentation tank of the lightweight medium rapid biological filter.

[0028] Explanation of the reference numbers: 1. Water inlet pipe of the filter unit; 2. Filter layer of the filter unit; 3. Water outlet pipe of the filter unit; 4. Top perforated baffle; 5. Bottom perforated baffle; 6. Stop valve for the sludge discharge pipe of the filter unit; 7. Sludge discharge pipe of the filter unit; 8. Stop valve for the water inlet pipe of the filter unit; 9. Stop valve for the water outlet pipe of the filter unit; 10. Water outlet weir of the secondary sedimentation tank. DETAILED DESCRIPTION

[0029] In order to further understand the content of the present invention, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the embodiments are only for explanation and not for limitation of the present invention.

[0030] See also Figure 1 、 Figure 2 and Figure 3There are several secondary sedimentation tank suspended lightweight medium rapid lightweight biological filter devices on the periphery of the secondary sedimentation tank. A filter unit water inlet pipe 1 is provided at the lower end of one side wall of the filter, and the filter unit water inlet pipe 1 is connected to the secondary sedimentation tank. A filter unit water outlet pipe 3 is provided at the upper end of the other side wall of the filter; the secondary sedimentation tank includes a secondary sedimentation tank outlet weir 10, and the filter unit water inlet pipe 1 of the filter is connected to the outlet pipe at the lower end of the secondary sedimentation tank outlet weir 10. A filter unit water inlet pipe stop valve 8 is installed on the filter unit water inlet pipe 1, and a filter unit water outlet pipe stop valve 9 is installed on the filter unit water outlet pipe 3; a filter unit filter layer 2 is arranged inside the filter tank, a top perforated baffle 4 is fixedly installed at the upper end of the filter unit filter layer 2, and a bottom perforated baffle 5 is installed at the lower end of the filter unit filter layer 2; the lower end of the filter tank is inclined, and a filter unit mud discharge pipe 7 is installed at the bottom of one side of the inclined direction, and a filter unit mud discharge pipe stop valve 6 is installed on the filter unit mud discharge pipe 7.

[0031] This embodiment proposes a secondary sedimentation tank suspended lightweight medium rapid biological filter, and its specific implementation is as follows:

[0032] In the sewage treatment plant, the suspended lightweight medium rapid biological filter proposed in the present invention is selected. Multiple independent lightweight biological filters are suspended outside the secondary sedimentation tank. The structure of each filter includes a filter unit water inlet pipe 1, a filter unit water outlet pipe 3, a filter unit mud discharge pipe 7, a filter unit filter layer 2, a top perforated baffle 4 and a bottom perforated baffle 5. In this embodiment, the filter material in the filter unit filter layer 2 is 0.02-0.05 g / cm 3Spherical polystyrene foam floating beads have a particle size of 4-6mm; the filter layer 2 of the filter unit can intercept the residual flocs in the effluent of the secondary sedimentation tank and form a biofilm on its surface, retaining microorganisms with long generations, degrading microbial metabolites and strong denitrification capabilities, further strengthening the removal of soluble components and improving the effluent water quality. The bottom perforated baffle 5 at the lower end of the filter layer 2 of the filter unit is movably installed in the filter tank. The bottom perforated baffle 5 is made of a lightweight hydrophobic material. During the backwashing process, the bottom perforated baffle 5 can float up and down slightly with the water flow. The top perforated baffle 4 at the upper end of the filter layer 2 of the filter unit is fixedly installed in the filter tank. It is a fixed baffle and will not float up and down or move with the filter layer 2 of the filter unit. It can prevent the filter material in the filter layer 2 of the filter unit from flowing out of the filter tank with the water flow. Both the top and bottom perforated baffles 4 and 5 are perforated with 3 mm diameter holes. The perforations in the top perforated baffle 4 are used to trap the spherical polystyrene foam beads in the filter layer 2 of the filter unit. These perforations prevent filter media loss while ensuring water flow. As water enters the filter tank, the upward force generated by the water flow causes the bottom perforated baffle 5 to move upward, driving the filter layer 2 upward. The filter layer 2 rises to the top perforated baffle 4, where it is gradually squeezed by the top perforated baffle 4 fixed at its upper end, forming a dense filter layer. During this process, the polystyrene foam beads in the filter layer, leveraging their large specific surface area and high surface potential, effectively capture residual sludge flocs and other solids in the secondary sedimentation tank effluent through a variety of mechanisms, including sedimentation, interception, inertia, diffusion, hydrodynamics, and velocity separation. Simultaneously, some dissolved pollutants are adsorbed on the filter media surface. The filtered water flows through the top outlet pipe to the outlet weir and enters the subsequent deep treatment unit or is directly discharged.

[0033] As the filtration time increases, the dense filter layer formed by the filter unit filter layer 2 traps a large amount of impurities, and the filtration effect gradually decreases until it penetrates. At this time, backwashing is performed. First, the filter unit water inlet pipe stop valve 8 on the filter unit water inlet pipe 1 is closed to stop water from entering the filter tank. At the same time, the filter unit mud pipe stop valve 6 on the filter unit mud pipe 7 is opened to drop the water level in the filter tank by several times the filter media particle size. As the water level in the filter tank drops, impurities and highly turbid water in the filter tank are discharged from the filter tank through the filter unit mud pipe 7 at the bottom under the action of gravity. During this removal process, impurities may be deposited at the bottom of the filter tank. Therefore, the bottom of the secondary sedimentation tank suspended lightweight medium rapid lightweight biological filter structure of this embodiment is designed to be inclined, and the filter unit mud pipe 7 is installed on one side of the inclination direction to ensure that the deposited impurities are further discharged through the filter unit mud pipe 7 due to gravity. Some filter media, whose density has increased due to the retention of excessive solids, also falls onto the bottom perforated baffle 5. Close the filter unit mud discharge pipe stop valve 6 on the filter unit mud discharge pipe 7, open the filter unit water inlet pipe stop valve 8 on the filter unit water inlet pipe 1, so that the water level in the filter tank rises several times the particle size again. At this time, the water flow drives the bottom perforated baffle 5 to float up and down, and the turbidity deposited on the bottom perforated baffle 5 is peeled off by the water flow shear. This cycle is repeated 3-5 times to complete the backwash, so that the bottom perforated baffle 5 floats again and restores the filtering performance.

[0034] This example demonstrates the practical application of a suspended lightweight media rapid biofilter in a sewage treatment plant. By effectively treating the effluent from the secondary sedimentation tank, it not only improves water quality and meets higher environmental standards, but also demonstrates significant advantages in economics and operating costs. This technology provides an economical, low-carbon, and intensive solution for the sewage treatment industry, with broad application prospects and potential for widespread adoption.

[0035] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A secondary sedimentation tank suspended light medium rapid biological filter, characterized in that: A plurality of light medium rapid light biological filters are suspended on the outer wall of the secondary sedimentation tank, including a filter unit filter layer (2), the filter unit filter layer (2) is arranged inside the filter tank, a top perforated baffle (4) is fixedly installed on the upper end of the filter unit filter layer (2), and a bottom perforated baffle (5) is movably installed on the lower end of the filter unit filter layer (2), a filter unit water inlet pipe (1) is arranged at the lower end of one side wall of the filter tank, the filter unit water inlet pipe (1) is connected to the secondary sedimentation tank, and a filter unit water outlet pipe (3) is arranged at the upper end of the other side wall of the filter tank.

2. A secondary sedimentation tank suspended light medium rapid biological filter according to claim 1, characterized in that: The filter material in the filter layer (2) of the filter unit is 0.02-0.05 g / cm 3 Spherical polystyrene foam beads with a particle size of 4-6mm.

3. The secondary sedimentation tank suspended light medium rapid biological filter according to claim 1, characterized in that: The top perforated baffle (4) is provided with perforations with a diameter of 3 mm.

4. The secondary sedimentation tank suspended light medium rapid biological filter according to claim 1, characterized in that: The bottom perforated baffle (5) is provided with perforations with a diameter of 3 mm.

5. The secondary sedimentation tank suspended light medium rapid biological filter according to claim 1, characterized in that: The secondary sedimentation tank includes a secondary sedimentation tank outlet weir (10), and the filter unit water inlet pipe (1) is connected to the secondary sedimentation tank outlet weir (10).

6. The secondary sedimentation tank suspended light medium rapid biofilter according to claim 5, characterized in that: The filter unit water inlet pipe (1) is provided with a filter unit water inlet pipe stop valve (8).

7. The secondary sedimentation tank suspended light medium rapid biological filter according to claim 1, characterized in that: The filter unit outlet pipe (3) is provided with a filter unit outlet pipe stop valve (9).

8. The secondary sedimentation tank suspended light medium rapid biofilter according to claim 1, characterized in that: The lower end of the filter tank is inclined at an angle of 30-45 degrees.

9. The secondary sedimentation tank suspended light medium rapid biofilter according to claim 8, characterized in that: A filter unit mud discharge pipe (7) is installed on one side of the lower end of the filter tank in the inclined direction.

10. The secondary sedimentation tank suspended light medium rapid biofilter according to claim 9, characterized in that: The filter unit mud discharge pipe (7) is provided with a filter unit mud discharge pipe stop valve (6).

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