Creature filtration device, water filtration system and method

Abstract

To provide a creature filtration device, a water filtration system and method capable of maintaining water quality.SOLUTION: A creature filtration device 100 comprises: a filtration material storage container 10; a filtration material 20 stored in the filtration material storage container 10; a water feeding pipe 30 for feeding treated water Wi to the filtration material storage container 10; and a discharge pipe 40 for discharging treatment water We from the filtration material storage container 10. The filtration material 20 is an aggregate obtained by laminating multiple granular materials. A water feeding hole 30a of the water feeding pipe 30 is arranged above a top end 20t of the aggregate. The discharge pipe 40 is below the top end 20t. The creature filtration device 100 can hold a water level L in the filtration material storage container 10 to a lower part lower than the top end 20t.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a biological filtration device, a water filtration system, and a water filtration method. [Background technology]

[0002] Conventionally, various types of filtration devices have been used to maintain the water quality of water in which living organisms such as fish and shellfish are raised or farmed on land. As time passes, microorganisms that decompose ammonia and nitrite settle in the voids formed inside the granules that make up the filter material used in the filtration device, and the biological filtration function increases. On the other hand, the voids in the filter material become clogged with dirt including organic matter such as excrement from living organisms and leftover food, so the physical filtration function decreases. When the filter material is washed to remove dirt, the physical filtration function is restored, but the biota that had settled in the voids is also removed by the washing, so it takes time to maintain the water quality by exerting the effect of biological filtration again after washing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 3769680 Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, the present invention has been made in consideration of the above problems, and an object of the present invention is to provide a biological filtration device, a water filtration system, and a water filtration method that can maintain water quality. [Means for solving the problem]

[0005] In order to achieve the above object, the following configuration is realized. (1) The biological filtration device of the present invention comprises a filter material storage container, a filter material stored in the filter material storage container, a water supply pipe for supplying treated water to the filter material storage container, and a drain pipe for draining the treated water from the filter material storage container, wherein the filter material is an assembly of a plurality of stacked granular bodies, the water supply port of the water supply pipe is located above the top end of the assembly, and the drain pipe is located below the top end, and the water level in the filter material storage container can be maintained below the top end. (2) In (1) above, the drain pipe may be located above the lower end of the assembly. (3) In the above (1) or (2), the water supply port opens upward. (4) In the above (1) or (2), the drain pipe may have a low-level drain pipe and a medium-level drain pipe, and may be equipped with an on-off valve capable of switching the flow of drainage to the low-level drain pipe or the medium-level drain pipe. (5) In (4) above, the drain pipe may have a high-level drain pipe located above the top end of the assembly, and may be equipped with an on-off valve capable of switching the flow of drainage to the high-level drain pipe, and may be equipped with a blower that generates a jet of air inside the filter material storage container. (6) A water filtration system equipped with the biological filtration device in (1) above may include an aquarium and a circulation channel through which water from the aquarium circulates, and the circulation channel may branch into a first channel returning to the aquarium and a second channel heading toward the biological filtration device. (7) The water filtration method using the biological filtration device in (1) above may include a removal step of removing a portion of the assembly from the filter material container, a cleaning step of cleaning the remainder of the assembly remaining in the filter material container, and a return step of returning the portion of the assembly to the filter material container and stacking it above the remainder. (8) In the above (7), a water-filling step may be included between the removing step and the washing step, in which water is added up to a water level above the top end of the remaining portion. (9) In the water filtration method using the biological filtration device in (5) above, the low water level drain pipe and the medium water level drain pipe may be closed and the high water level drain pipe may be open, and the blower may be started to agitate the filter material. Effect of the Invention

[0006] According to the present invention, it is possible to provide a biological filtration device, a water filtration system, and a water filtration method that can maintain water quality. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an overall view of a water filtration system. [Diagram 2] FIG. 1 is a schematic diagram of a biological filtration device according to a first embodiment. [Diagram 3] FIG. 2 is a schematic diagram of a biological filtration device during normal operation at mid-water level. [Figure 4] FIG. 2 is a schematic diagram of a biological filtration device during normal operation at low water levels. [Diagram 5] FIG. 2 is a schematic diagram of a biological filtration device during cleaning. [Figure 6] FIG. 2 is a schematic diagram of a biological filtration device immediately after cleaning. [Figure 7] FIG. 11 is a schematic diagram of a water supply port of a biological filtration device according to a second embodiment. [Figure 8] 8 is a cross-sectional view taken along the line A in FIG. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (First embodiment) A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG 1 is an overall view of the water filtration system S. FIG 2 is a schematic diagram of the biological filtration device 100 according to the first embodiment. FIG 3 is a schematic diagram of the biological filtration device 100 during normal operation at a medium water level. FIG 4 is a schematic diagram of the biological filtration device 100 during normal operation at a low water level. FIG 5 is a schematic diagram of the biological filtration device 100 during cleaning. FIG 6 is a schematic diagram of the biological filtration device 100 immediately after cleaning. In the following, an example will be described in which the biological filtration device 100 is applied to the circulating water channel C of a water filtration system S for cultivating aquatic organisms such as fish and shellfish. The biological filtration device 100 is not limited to being applied to livestock farming, in which aquatic organisms such as fish and shellfish are temporarily raised in a pond or the like before being shipped, but may also be applied to a water filtration system S for aquaculture, in which organisms are artificially cultivated and multiplied. Note that normal operation refers to a state in which aquatic organisms are cultivated by the water filtration system S, and is a concept that is distinct from when the biological filtration device 100 is being cleaned.

[0009] (Water Filtration System) As shown in Fig. 1, the water filtration system S includes an aquarium 200 and a circulation channel C through which the water in the aquarium 200 circulates. The water filtration system S circulates running water in the direction indicated by the arrow in the circulation channel C that loops from aquarium 200 to aquarium 200. Note that, in the middle of the circulation channel C (for example, at aquarium 200), new water may be appropriately poured in to make up for evaporated running water, or part of the running water may be drained.

[0010] The water filtration system S mainly comprises an aquarium 200 for raising aquatic organisms such as fish and shellfish, a biological filtration device 100 for performing ammonia nitrification from wastewater from the aquarium 200, and a first pump P for supplying power to circulate running water within the circulation channel C. The first pump P may be provided immediately after the aquarium 200 in the circulating water channel C, or immediately after the biological filtration device 100.

[0011] The water filtration system S may optionally include a physical filtration device 300 that removes coarse solids and suspended solids (also referred to as SS) from wastewater (filtered water, breeding water) from the aquarium 200. The physical filtration device 300 is preferably provided upstream of the biological filtration device 100.

[0012] The water filtration system S may optionally include a sterilization device 400 that sterilizes the wastewater from the physical filtration device 300. The sterilization device 400 may be, for example, a UV sterilization device that sterilizes with ultraviolet light. The sterilization device 400 is preferably provided upstream of the biological filtration device 100. The sterilization device 400 may also be provided downstream of the biological filtration device 100.

[0013] Here, the return water channel C may be branched into a first water channel C1 returning to the aquarium 200 and a second water channel C2 leading to the biological filtration device 100. This allows a portion of the water to be treated from the aquarium 200 flowing through the return water channel C to be returned to the aquarium 200, and the remainder to be directed to the biological filtration device 100, so that the flow rate and volume of the water flowing through the return water channel C can be kept high, and the load on the first pump P can be reduced.

[0014] (Biological filtration device) The biological filtration device 100 of the first embodiment comprises a filter material container 10, a filter material 20 contained in the filter material container 10, a water supply pipe 30 that supplies the treated water Wi to the filter material container 10, and a drain pipe 40 that drains the treated water We from the filter material container 10.

[0015] The filter medium container 10 has a rigidity sufficient to withstand the water pressure of running water and may be made of acrylic or polyvinyl chloride. It is preferable that the filter medium container 10 is transparent so that the state of the inside, such as the degree of dirt of the filter medium 20, can be confirmed.

[0016] The upper part of the filtration medium container 10 is open to the atmosphere in order to naturally supply air to the microorganisms that have settled on the filtration medium 20. In other words, the upper part of the filtration medium container 10 is not sealed with a lid. This can promote the maturation of the microorganisms and facilitate the settlement of the microorganisms on the filtration medium 20.

[0017] The filtering medium container 10 has a blower 11 for passing a jet of air (aeration) from below to above during cleaning. The blower 11 generates a jet of air inside the filtering medium container 10. A nozzle 12 connected to the blower 11 is provided at the lower part of the inside of the filtering medium container 10 facing upward. This allows a jet of air (aeration) from below to above to be generated when the filtering medium container 10 is filled with running water. Therefore, the collection of filtering media 20 stacked inside the filtering medium container 10 can be cleaned (backwashed) inside the filtering medium container 10 without removing it from the filtering medium container 10. Therefore, the sludge that has been generated by biological filtration and has clogged the fine gaps of the filtering medium 20 can be removed from the filtering medium 20, and the space for living organisms can be restored, restoring the biological filtration function of the filtering medium 20. In addition, during normal operation, the filter material 20 can be used as a fluidized bed by using the air jet from the blower 11 to agitate the filter material 20, thereby promoting the formation of a biofilm on the filter material 20. In this way, the blower 11 can be used for both backwashing and the fluidized bed.

[0018] The lower part of the filtration medium storage container 10 has a perforated plate 13 on which the filtration medium 20 can be placed and through which an air jet directed from below to above can pass during cleaning. The perforated plate 13 has a plurality of holes of a size that allows air from the nozzle 12 to pass through without passing through the filtration medium 20. This allows the collection of filtration media 20 stacked inside the filtration medium storage container 10 to be evenly agitated during backwashing, and the filtration media 20 can be effectively cleaned.

[0019] A drain 14 capable of draining the water to be treated that has accumulated in the filtration material-housing container 10 is provided at the bottom of the filtration material-housing container 10. This allows, for example, water used to clean the filtration material-housing container 10 or water used to wash the filtration material 20 to be drained from the filtration material-housing container 10.

[0020] The filter material 20 is an assembly of a plurality of granular bodies stacked on top of one another. The granular bodies constituting the filter material 20 are preferably elastic bodies formed to be porous. The filter material 20 is formed, for example, from polyvinyl alcohol (hereinafter, sometimes referred to as "PVA"), and has a high adsorption capacity for bacteria and suspended solids (SS, dust particles in water) that grow in water, and has excellent water filtering capabilities. The filter material 1 is mainly composed of polyvinyl alcohol, and may contain impurities to the extent that they do not inhibit physical filtration and biological filtration by microorganisms such as nitrifying bacteria. The filter material 20 is, for example, 3 cm thick. 3 From 8cm 3 The filter medium 20 is a cube or sheet-like body having a bulk volume of 3000 m. The filter medium 20 has a cell structure of completely open cells with an average bubble diameter of about 450 μm to 1500 μm. 2 / m 3 4000m from 2 / m 3 The filtration medium 20 is a granular material made of PVA resin, having a specific surface area of ​​100 nm and a porosity of 80% to 96%. For ease of handling, the aggregate of the filtration medium 20 may be a collection of a plurality of groups of granular materials, each group being made up of a plurality of granular materials put into a net.

[0021] Here, the water supply port 30a is above the top end 20t of the assembly of the filter media 20. The drain pipe 40 is below the top end 20t of the assembly of the filter media 20. The water head at the water level L in the filter media container 10 is the same as the water head at the height where the drain pipe 40 is provided (for example, the height where the mid-water level drain pipe 40M is provided), so the biological filtration device 100 can maintain the water level L in the filter media container 10 below the top end 20t. This allows the upper part of the assembly of the filter media 20 above the water level L in the filter media container 10 to be exposed to air and to be able to receive the water to be treated Wi sprayed from the water supply port 30a. Therefore, by abundantly supplying air and water to be treated Wi to the filter media 20, the microorganisms settled on the filter media 20 can be activated. Therefore, according to the biological filtration device 100, the physical filtration function can be restored by cleaning the filter medium 20, and the biological filtration function can be quickly restored, so that the water quality of the water flowing through the circulating water channel C including the aquarium 200 can be maintained. The water supply port 30a may be single or multiple.

[0022] The water supply port 30a opens upward. This allows the water to be treated Wi to be evenly sprayed over the upper surface of the top end 20t of the assembly of the filter media 20 exposed to air. This allows the water to be treated Wi and air to be evenly supplied to the entire filter media 20, allowing the biological filtration device 100 to efficiently perform its biological filtration function.

[0023] The drain pipe 40 (at its height) is preferably below the top end 20t of the assembly of the filter media 20 and above the bottom end 20b of the assembly of the filter media 20. This allows the lower part of the assembly of the filter media 20, which is below the water level L, to be submerged in water. Therefore, when the filter media 20 with less microorganisms (immediately after cleaning) is arranged at the lower part of the assembly and the filter media 20 with more microorganisms (not cleaned) is arranged at the upper part of the assembly, some of the microorganisms that have been settled on the filter media 20 at the upper part can be transferred to the filter media 20 at the lower part by the flow of the water to be treated Wi in the direction of gravity. Therefore, the settlement of microorganisms on the filter media 20 with less microorganisms (immediately after cleaning) can be promoted. Therefore, according to the biological filtration device 100, the physical filtration function can be restored by cleaning the filter media 20, and the biological filtration function can be quickly restored, so that the water quality of the water flowing through the circulating water channel C including the water tank 200 can be maintained.

[0024] The drain pipe 40 may have a low-level drain pipe 40L and a medium-level drain pipe 40M. The drain pipe 40 may have an on-off valve 41 capable of switching the flow of drainage to the low-level drain pipe 40L or the medium-level drain pipe 40M. The drain pipe 40 may have a high-level drain pipe 40H as appropriate. The drain pipe 40 may have an on-off valve 41 capable of switching the flow of drainage to the high-level drain pipe 40H as appropriate.

[0025] When priority is given to decomposing ammonia nitrogen, it is preferable to open the low water level drain pipe 40L and perform normal operation at a low water level in order to increase the activity of aerobic organisms that decompose ammonia nitrogen. When priority is given to promoting denitrification of nitrate nitrogen, it is preferable to close the low water level drain pipe 40L and perform normal operation at a medium or high water level in order to increase the activity of anaerobic organisms that denitrify nitrate nitrogen. Then, the water quality (ammonia nitrogen concentration, nitrate nitrogen concentration, etc.) in the aquarium 200 or the circulating water channel C including the biological filtration device 100 may be checked, and the water level L may be controlled according to the water quality. This allows the biological filtration to function effectively, improving the water quality.

[0026] The low-level drain pipe L is provided below the height position at which the medium-level drain pipe 40M is provided, preferably at the position of the screen 13, that is, below the lower end 20b of the filter media 20 assembly.

[0027] The mid-level drain pipe 40M is provided at a height position intermediate between the top end 20t and the bottom end 20b. The mid-level drain pipe 40M is preferably provided at a height position that divides the area between the top end 20t and the bottom end 20b in half.

[0028] The high water level drain pipe 40H is provided at a height equal to or higher than the top end 20t, or equal to the upper end of the filtration medium container 10.

[0029] The on-off valve 41 may be provided separately for each of the water filtration systems S, or may be a three-way valve or a switching valve. As a result, for example, during normal operation of the water filtration system S, as shown in FIG. 3, the water level L can be maintained between the top end 20t and the bottom end 20b of the assembly by operating the on-off valve 41 to open the medium water level drain pipe 40M and close (optionally) the low water level drain pipe 40L and the high water level drain pipe 40H, so that the water level L can be maintained below the bottom end 20b of the assembly. Also, for example, during normal operation of the water filtration system S, when the filtration medium 20 is completely exposed to air, the water level L can be maintained below the bottom end 20b of the assembly by operating the on-off valve 41 to open the low water level drain pipe 40L and close the medium water level drain pipe 40M and the high water level drain pipe 40H. Also, for example, when cleaning the water filtration system S (biological filtration device 100), the water level L can be maintained at or above the top end 20t of the assembly by operating the on-off valve 41 to close the low water level drain pipe 40L and the medium water level drain pipe 40M and open the high water level drain pipe 40H.

[0030] In this way, the drain pipe 40 has a low water level drain pipe 40L and a medium water level drain pipe 40M, so that the water level L can be adjusted depending on the situation in which the water filtration system S is operating (normal operation, cleaning, etc.) and the environment, such as air temperature or water temperature.

[0031] In addition, when the drain pipe 40 has a low water level drain pipe 40L, a medium water level drain pipe 40M, and a high water level drain pipe 40H, the height of the high water level drain pipe 40H is located above the top end 20t of the assembly, so that the water level L can be maintained above the top end 20t of the assembly by operating the on-off valve 41 to close the low water level drain pipe 40L and the medium water level drain pipe 40M. In other words, by operating the on-off valve 41 to close the low water level drain pipe 40L and the medium water level drain pipe 40M, the water level L can be maintained high and the assembly can be completely submerged in water. When the water level L is kept high in this way and normal operation is performed (while maintaining the flow of the water Wi from the water supply pipe 30 to the drain pipe 40 by the first pump P), and the blower 11 is driven to generate a jet of air (aeration) in the filtration medium container 10, the filtration medium 20 can be suspended and suspended in the water in the filtration medium container 10 (fluidized bed). This can promote the formation of a biological film on the filter material 20, and since the filter material 20 is constantly stirred by aeration, the contact efficiency with the water to be treated Wi can be increased. Thus, the biological filtration function of the biological filtration device 100 can be promoted. Furthermore, if the drain pipe 40 has a low-water level drain pipe 40L, a medium-water level drain pipe 40M, and a high-water level drain pipe 40H, the water level L can be raised and backwashed by operating the on-off valve 41 to close the low-water level drain pipe 40L, the medium-water level drain pipe 40M, and the high-water level drain pipe 40H, thereby stopping the flow of the treated water Wi from the water supply pipe 30 to the drain pipe 40 (stopping the first pump P).

[0032] 1 and 2, the biological filtration device 100 preferably includes a second pump P2 that takes the water in the filter medium container 10 from below the filter medium container 10 and merges it into the water supply pipe 30 to circulate it. This increases the amount of water passing through the filter medium 20, promoting the biological filtration function and reducing the load on the first pump P.

[0033] 2, the biological filtration device 100 may have a raised portion 16 that is detachably attached to the upper end of the filtration medium-containing container 10 and is added to increase the height of the filtration medium-containing container 10 to become part of the side wall of the container. This makes it possible to increase the maximum amount (maximum height) of filtration medium 20 that can be contained in the filtration medium-containing container 10, and to stack new filtration medium 20 on top of the existing filtration medium 20, thereby improving biological filtration performance.

[0034] (Filtration method) Next, a method for filtering water to be treated by the water filtration system S using the biological filtration device 100 will be described.

[0035] (A1) First, as shown in FIG. 1, the aquarium 200 and the biological filtration device 100 are installed in the return water channel C of the water filtration system S. The biological filtration device 100 may be additionally installed in the return water channel C of the water filtration system S in which the aquarium 200 has been installed beforehand. The physical filtration device 300 and / or the sterilization device 400 are appropriately installed in the return water channel C of the water filtration system S. At this time, as shown in FIG. 3, in the biological filtration device 100, the assembly of the filter media 20 is placed so as to be stacked on the screen 13. The assembly of the filter media 20 is stacked in the range from the lower end 20b, which is the same height as the upper surface of the screen 13, to the top end 20t, which is approximately the same height as the high water level drain pipe 40H. The operation of the blower 11 is stopped.

[0036] (A11) Here, in the biological filtration device 100 during normal operation at a medium water level, the low water level drain pipe 40H is closed and the medium water level drain pipe 40M is open, as shown in Fig. 3. The high water level drain pipe 40L may be opened or closed as desired. Here, the high water level drain pipe 40L is left open.

[0037] (A12) Here, in the biological filtration device 100 during normal operation at a low water level, the low water level drain pipe 40L is left open as shown in Fig. 4. The medium water level drain pipe 40M and the high water level drain pipe 40H can be opened or closed as desired. Here, the medium water level drain pipe 40M and the high water level drain pipe 40H are left open.

[0038] (A13) Here, in the biological filtration device 100 during normal operation at a high water level, the low water level drain pipe 40L and the medium water level drain pipe 40M are closed, and the high water level drain pipe 40H is open. During normal operation, the blower 11 is driven to constantly stir and fluidize the filter material 20 together with aeration. In this way, the biological filtration device 100 can also be used as a fluidized bed.

[0039] (A21) Next, the first pump P is started to circulate the water Wi from the water tank 200 through the return water channel C. Then, in the biological filtration device 100 during normal operation at the mid-water level, as shown in FIG. 3, the water Wi is discharged from the water supply port 30a of the water supply pipe 30 provided at the top of the filter medium container 10 of the biological filtration device 100. When the water supply port 30a faces upward, the water Wi discharged from the water supply port 30a falls evenly on the top end 20t of the assembly of the filter medium 20 like a shower, which is preferable. The water Wi flows from the top to the bottom of the assembly of the filter medium 20 in the direction of gravity while impurities are filtered by physical action by contacting the filter medium 20 and ammonia nitrogen, which is highly toxic to fish, is decomposed by biological action to be weakened, and is discharged into the drain pipe 40. Then, the water level L is stabilized at a height approximately equal to that of the mid-water level drain pipe 40M. The lower part of the assembly of the filter media 20 is immersed in the water to be treated Wi, and the upper part is exposed to air. At this time, the second pump P2 may be driven to circulate the water in the filter media container 10.

[0040] (A22) In the biological filtration device 100 during normal operation at a low water level, as shown in FIG. 4, the treated water Wi is discharged from the water supply port 30a of the water supply pipe 30 provided at the top of the filter medium container 10, similarly to the biological filtration device 100 during normal operation at a medium water level. The treated water Wi flows in the direction of gravity from the top to the bottom of the assembly of the filter medium 20 while being filtered of impurities by physical action and attenuated by biological action by contacting the filter medium 20, and is drained into the drain pipe 40. Then, the water level L is stabilized at a height approximately equal to that of the low water level drain pipe 40L. Then, the entire assembly of the filter medium 20 is exposed to air.

[0041] (A3) After the water filtration system S has been in operation for a predetermined period of time, the filter media 20 is washed to restore the filtering function of the biological filtration device 100. At this time, the first pump P is stopped. Then, as shown in Fig. 5, the low water level drain pipe 40L and the medium water level drain pipe 40M are closed. Note that the high water level drain pipe 40H can be opened or closed as desired, but here, the high water level drain pipe 40H is closed. Then, a portion B of the assembly of filter media 20 is removed from the filter media-containing container 10 (removal step). Specifically, for example, approximately half of the entire assembly of filter media 20 is removed from the removal port 15 provided on the side surface of the filter media-containing container 10.

[0042] (A4) Then, as shown in FIG. 5, the filtration medium container 10 is filled with water up to a water level L above the top end 20t of the remaining part A of the assembly of the filtration medium 20 (water addition step).

[0043] (A5) Next, the remaining part A of the assembly remaining in the filtration medium container 10 is washed (washing process). At this time, the blower 11 is started and air is sprayed upward from the nozzle 12. This creates a jet of air inside the filtration medium container 10, so that the remaining part A can be washed effectively.

[0044] (A6) Next, as shown in FIG. 6, a part B of the assembly of filter media 20 removed in the previous water addition step is returned to the filter media storage container 10 and stacked above the remaining part A of the assembly (returning step).

[0045] (A7) Then, the operation of the first pump P is resumed. That is, the filtration of the water to be treated Wi by the water filtration system S is resumed. In the biological filtration device 100 during normal operation at a medium water level, the low water level drain pipe 40L is closed and the medium water level drain pipe 40M is open, as shown in Fig. 6. Note that the high water level drain pipe 40H can be opened or closed as desired, but in this example, the high water level drain pipe 40H is left open. In the biological filtration device 100 during normal operation at a low water level, as shown in FIG. 4, the low water level drain pipe 40L, the medium water level drain pipe 40M, and the high water level drain pipe 40H are opened. Then, as shown in FIG. 6, the water to be treated Wi is discharged from the water supply port 30a of the water supply pipe 30 provided at the top of the filter medium container 10 of the biological filtration device 100. The water to be treated Wi flows from the top to the bottom of the assembly of the filter medium 20 in the direction of gravity while being filtered of impurities by physical action and attenuated by biological action by contacting the filter medium 20, and is drained into the drain pipe 40. During normal operation at the medium water level, the water level L is stable at a height approximately equal to that of the medium water level drain pipe 40M. During normal operation at the low water level, the water level L is stable at a height approximately equal to that of the low water level drain pipe 40L. During normal operation at the medium water level, the lower part of the assembly of the filter medium 20 is immersed in the water to be treated Wi, and the upper part is exposed to air. During normal operation at the low water level, the entire assembly of the filter medium 20 is exposed to air. Here, the remaining part A of the assembly of the filter media 20 is washed, and blockages caused by dead biofilms and the like are removed, so that the physical filtration function is restored, but the biological filtration function is reduced. On the other hand, the part B of the assembly of the filter media 20 is not washed, so that the physical filtration function is reduced, but the biological filtration function is maintained at a high level. Therefore, since the part B of the assembly of the filter media 20 is located above the part A, some of the microorganisms that have settled in the part B are transferred to the part A by the flow of the water to be treated Wi, and the re-settlement of the microorganisms in the part A can be promoted. In addition, the upper part of the assembly of the filter media 20 above the water level L can be exposed to air and can be made to receive the water to be treated Wi sprayed from the water supply port 30a. Therefore, by supplying air and the water to be treated Wi abundantly to the filter media 20, the microorganisms that have settled on the filter media 20 can be activated. In this way, the physical filtration function of the entire assembly of the filter media 20 can be restored, and the recovery of the biological filtration function can be accelerated.

[0046] Second embodiment Next, the biological filtering device 100 according to the second embodiment will be described in detail. Note that, hereinafter, descriptions of matters common to the biological filtering device 100 according to the first embodiment may be omitted. Fig. 7 is a detailed view of the water supply pipe 30 of the biological filtration device 100 according to the second embodiment. Fig. 8 is a cross-sectional view taken along the line A in Fig. 7.

[0047] The biological filtration device 100 of the second embodiment is not shown in Figure 7, but as shown in Figure 2, similar to the biological filtration device 100 of the first embodiment, it is equipped with a filter material container 10, a filter material 20 contained in the filter material container 10, a water supply pipe 30 that supplies the treated water Wi to the filter material container 10, and a drain pipe 40 that drains the treated water We from the filter material container 10.

[0048] The water supply port 30a of the water supply pipe 30 is located above the top end 20t of the assembly. The drain pipe 40 is located below the top end 20t. The biological filtration device 100 can maintain the water level L in the filter medium container 10 below the top end 20t.

[0049] Here, the water supply pipe 30 has a plurality of water supply ports 30a that open in different directions, as shown in Figures 7 and 8. This allows the water coming out of the water supply ports 30a to be evenly sprayed onto the top end 20t of the assembly.

[0050] The water inlet 30a may open upward, including diagonally upward. This increases the horizontal distance that water discharged from one water inlet 30a can reach, and expands the watering range. Therefore, the water discharged from the water inlet 30a can be evenly sprayed by the top edge 20t of the assembly.

[0051] A plurality of water supply ports 30a may be provided along the extension direction of the sprinkler pipe 32. This allows the range of water sprinkling to be expanded. The water supply ports 30a may be provided regularly, such as at equal intervals, along the extension direction of the sprinkler pipe 32, or the water supply ports 30a may be provided at irregular intervals along the extension direction of the sprinkler pipe 32. The water supply ports 30a may be provided in a single row along the extension direction of the sprinkler pipe 32, or in two or more rows along the extension direction of the sprinkler pipe 32.

[0052] The water supply pipe 30 has a support pipe 31 and a sprinkler pipe 32 that is supported by the support pipe 31 and extends substantially horizontally. Note that a plurality of sets of support pipes 31 and sprinkler pipes 32 may be provided for one water supply pipe 30. It is not limited to providing two sprinkler pipes 32 for one support pipe 31, but one sprinkler pipe 32 may be provided, or three or more sprinkler pipes 32 may be provided. When a plurality of sprinkler pipes 32 are provided, they may be arranged so that their extension directions are parallel to each other, or so that their extension directions are different.

[0053] The sprinkler pipe 32 is a hollow pipe. The sprinkler pipe 32 may be a pipe extending in a straight line. One end of the sprinkler pipe 32 is closed, and the other end is connected to the support pipe 31. The sprinkler pipe 32 is provided with a plurality of water supply ports 32a.

[0054] 7, for example, a plurality of water supply ports 30a are provided at equal intervals in two rows for each sprinkler pipe 32 along the extension direction of the sprinkler pipe 32. The angle between the rows of water supply ports 30a is approximately 90 degrees about the axis g in a cross-sectional view perpendicular to the extension direction of the sprinkler pipe 32.

[0055] 8, water supply port 32a opens in a direction inclined by, for example, 45 degrees with respect to a vertical line G passing through the axis (a line connecting the centroid of the cross section in the extension direction) g in a cross section perpendicular to the extension direction of sprinkler pipe 32. This makes it possible to increase the flight distance of water discharged from water supply port 32a and to widen the range of sprinkling.

[0056] The support pipe 31 supports the sprinkler pipe 32 so as to be freely rotatable. This allows the direction of the water supply port 30a provided on the sprinkler pipe 32 to be changed. This allows adjustment so that the sprinkled water is evenly distributed over the top end 20t of the assembly. Specifically, the support pipe 31 may be a T-shaped joint having three joints, which is called a T-shaped joint and is used in the branching part of the piping. The first joint of the support pipe 31 is connected to the main water supply pipe 30 before the branching. The support pipe 31 supports one pipe-shaped sprinkler pipe 32 in a state where it is fitted into the second joint. The support pipe 31 supports one pipe-shaped sprinkler pipe 32 in a state where it is fitted into the remaining joint. The support pipe 31 and the sprinkler pipe 32 may be joined by tapered surfaces, or may be joined by a screw (seal screw or tapered screw as appropriate).

[0057] Since the sprinkler pipe 32 is rotatably supported by the support pipe 31, when it is rotated (for example, 180 degrees) about the axis g, the opening direction of the water supply port 32a can be changed from upward (upper view of FIG. 8) to downward (lower view of FIG. 8) as shown in Fig. 8. Therefore, by using the sprinkler pipe 32 rotatably supported by the support pipe 31, the range of water sprinkling can be adjusted according to the width of the top end 20t of the assembly.

[0058] Although the preferred embodiments of the present invention have been described in detail above, the biological filtration device, water filtration system, and water filtration method of the present invention are not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the gist of the present invention described in the claims.

[0059] As described above, the biological filtration device 100 according to the embodiment includes a filter container 10, a filter 20 contained in the filter container 10, a water supply pipe 30 for supplying the water to be treated Wi to the filter container 10, and a drain pipe 40 for draining the treated water We from the filter container 10. The filter 20 is an assembly of a plurality of stacked granules. The water supply port 30a of the water supply pipe 30 is above the top end 20t of the assembly. The drain pipe 40 is below the top end 20t. The water level L in the filter container 10 can be maintained below the top end 20t. This allows the upper part of the assembly of the filter 20 above the water level L in the filter container 10 to be exposed to air and to receive the water to be treated Wi sprayed from the water supply port 30a. Therefore, by abundantly supplying air and water to be treated Wi to the filter 20, the microorganisms settled on the filter 20 can be activated. Therefore, according to the biological filtration device 100, the physical filtering function can be restored by cleaning the filter medium 20, and the biological filtering function can be quickly restored, so that the water quality of the water flowing through the circulating water channel C including the aquarium 200 can be maintained.

[0060] The water filtration system S according to the embodiment includes an aquarium 200 and a return channel C through which the water in the aquarium 200 circulates. The return channel C branches into a first channel C1 that returns to the aquarium 200 and a second channel C2 that leads to the biological filtration device 100. This allows a portion B of the water to be treated from the aquarium 200 that flows through the return channel C to be returned to the aquarium 200, and the remaining portion A to be directed to the biological filtration device 100, so that the flow rate and volume of the water flowing through the return channel C can be kept high and the load on the first pump P can be reduced. Therefore, the water filtration system S can maintain the quality of the water flowing through the return channel C including the aquarium 200.

[0061] The filtration method according to the embodiment includes a removal step of removing a part B of the assembly from the filtration medium container 10, a washing step of washing the remaining part A of the assembly remaining in the filtration medium container 10, and a return step of returning the part B of the assembly to the filtration medium container 10 and stacking it above the remaining part A. This makes it possible to recover the physical filtering function of the entire assembly of the filtration medium 20, and to hasten the recovery of the biological filtering function. Therefore, this filtration method makes it possible to maintain the water quality of the water flowing through the circulating water channel C including the aquarium 200. [Explanation of symbols]

[0062] 10 Filter media container 100 Biological filtration device 11 Blower 12 Nozzles 13. Plate 14 Drain 20 Filter material 200 Aquarium 20b bottom end 20t Top 30 Water supply pipe 31 Support pipe 32 Sprinkler pipe 300 Physical Filtration Device 30a Water inlet 40 Drain pipe 400 Sterilizer 40H high water level drain pipe 40M medium water level drain pipe 40L low water drain pipe 41 On-off valve C Ring waterway C1 1st waterway C2 2nd waterway L water level P First pump P2 Second pump S Water Filtration System We Treated Water Wi Treated water g axis center G plumb line

Claims

1. The present invention comprises a filtration medium container, a filter contained in the filtration medium container, a water supply pipe for supplying water to be treated to the filtration medium container, and a drain pipe for draining the treated water from the filtration medium container, The filter material is an aggregate of a plurality of granular bodies stacked together, The water supply port of the water supply pipe is located above the top end of the assembly, The drain pipe is located below the top end, The water level in the filter medium container can be maintained below the top end. Biological filtration system.

2. The drain pipe is above the lower end of the assembly. The biological filtration device according to claim 1 .

3. The water supply port opens upward. The biological filtration device according to claim 1 or 2.

4. The drain pipe includes a low water level drain pipe and a medium water level drain pipe, The system is provided with an on-off valve capable of switching the flow of drainage to the low-level drain pipe or the medium-level drain pipe. The biological filtration device according to claim 1 or 2.

5. The drain pipe includes a high water level drain pipe located above the top end of the assembly, An on-off valve capable of switching the flow of drainage to the high water level drain pipe is provided, A blower is provided to generate a jet of air in the filter medium container. The biological filtration device according to claim 4.

6. The apparatus includes a water tank and a circulation channel through which water from the water tank circulates; The return water channel branches into a first water channel returning to the aquarium and a second water channel leading to the biological filtration device. A water filtration system comprising the biological filtration device according to claim 1.

7. a removing step of removing a portion of the assembly from the filter medium container; a cleaning step of cleaning the remaining part of the assembly remaining in the filter medium container; and returning a portion of the assembly to the filter medium container and stacking the portion above the remaining portion. A water filtration method using the biological filtration device according to claim 1.

8. Between the removing step and the cleaning step, A water-filling step is included, which fills the water up to a water level above the top of the remaining portion. The method for filtering water according to claim 7.

9. The low water level drain pipe and the medium water level drain pipe are closed and the high water level drain pipe is opened, and the blower is started to agitate the filter material. A water filtration method using the biological filtration device according to claim 5.

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