JP2013212443A - Solid/liquid separator and method of cleaning solid/liquid separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid/liquid separator capable of maintaining a high SS removal rate simply and a method of cleaning a solid/liquid separator.SOLUTION: A solid/liquid separator 1 generates an upward stream with to-be-filtrated water W1 supplied to a filtration vessel 10 and separates the solid contents in the to-be-filtrated water W1 to produces filtrate W2. The solid/liquid separator 1 includes: an upper filtration precipitation section which has an upper screen 2, a lower screen 3 and an upper filtration precipitation layer 4 formed by filling an upper space sandwiched by the upper screen 2 and the lower screen 3 with an upper filter medium 4a of a specific gravity equal to or higher than 0.8 and lower than 1.0; and a lower filtration section which has a lower filtration layer 5 formed by filling a lower space between the lower screen 3 and the bottom of the filtration vessel 10 with a lower filter medium 5a of a specific gravity equal to or higher than 0.1 and lower than 0.8.

Description

  The present invention relates to a solid-liquid separation device that generates an upward flow from the filtration target water supplied to the filtration tank, and separates the solid content in the filtration target water to generate filtered water, and a method for cleaning the solid-liquid separation device About.

  Conventionally, in wastewater treatment including organic components such as sewage, first, it is first introduced into a settling basin and solid-liquid separated by natural sedimentation. The first sedimentation effluent, from which relatively large solids that spontaneously settle, are separated, is sent to the reaction tank and mixed with activated sludge for biological treatment. Then, it is separated into precipitated solid and liquid by the final sedimentation basin and separated into treated water and activated sludge. The separated treated water is discharged into rivers. On the other hand, a part of the activated sludge is returned to the reaction tank as return sludge and used again for the decomposition of organic matter. However, the activated sludge flowing out from the reaction tank has unstable properties, and the SS (Suspended Solid) concentration may be high in the treated water discharged after solid-liquid separation in the final sedimentation basin in the subsequent stage.

  For this reason, in patent document 1, the SS removal rate is raised by providing the filter-medium filling part filled with the cylindrical floating filter medium whose specific gravity is less than 1.0, and letting process target water pass upward.

Japanese Patent No. 3015274

  By the way, the specific gravity of the cylindrical floating filter described above is less than 1.0, preferably about 0.9, and when backwashing is performed by generating a downward flow, Because it has almost the same specific gravity, it flows out with the downward flow. For this reason, in order to prevent the floating filter medium from flowing out, in addition to the upper screen provided above the filter medium layer, a lower screen is provided below the filter medium layer.

  However, since this lower screen allows the water to be filtered before being filtered into the filter medium layer to pass through, the lower screen becomes entangled with contaminants such as hair and paper in the water to be filtered during long-term operation. There is a problem that it occurs and the filtration capacity is lowered. The cleaning for eliminating the clogging is a manual operation using a brush or the like, and requires a great deal of labor.

  This invention is made in view of the above, Comprising: It aims at providing the washing | cleaning method of the solid-liquid separation apparatus and solid-liquid separation apparatus which can suppress clogging while obtaining high SS removal rate. .

  In order to solve the above-described problems and achieve the object, the solid-liquid separation device according to the present invention generates an upward flow by the filtration target water supplied to the filtration tank, and converts the solid content in the filtration target water. A solid-liquid separation device that generates filtered water by separation, and has an upper screen and a lower screen, and has a specific gravity of 0.8 or more in an upper space sandwiched between the upper screen and the lower screen. The specific gravity is 0.1 or more and less than 0.8 in the lower filtration space between the upper filtration sedimentation portion filled with less than 0 upper filtration material to form the upper filtration sedimentation layer and the lower screen and the bottom of the filtration tank. The lower filtration part which fills the lower filter material of this and forms a lower filtration layer, It is characterized by the above-mentioned.

  The solid-liquid separation device according to the present invention is characterized in that, in the above-mentioned invention, the bottom of the filtration tank is provided with a discharge pipe for discharging washing waste water, and the height between the lower screen and the bottom of the filtration tank is When the cleaning is performed to open the discharge pipe and generate a downward flow, the lower filter medium has a thickness that develops downward corresponding to the specific gravity.

  The solid-liquid separator according to the present invention is characterized in that, in the above-mentioned invention, the upper filter medium is a floating filter medium having a specific surface area larger than that of the lower filter medium.

  In the solid-liquid separator according to the present invention, the height between the lower screen and the bottom of the filtration tank is 1.5 times or more the thickness of the lower filtration layer. It is characterized by.

  In the solid-liquid separation device according to the present invention, in the above-described invention, a discharge pipe that discharges cleaning wastewater to the bottom of the filtration tank, and a suction pipe that is provided in the discharge pipe and sucks and discharges the cleaning wastewater. And a pump.

  The solid-liquid separation device cleaning method according to the present invention includes an upper screen and a lower screen in a filtration tank, and a specific gravity of 0.8 or more in an upper space sandwiched between the upper screen and the lower screen. The specific gravity of the lower filtration space between the lower screen and the bottom of the filter tank is 0.1 or more, 0. A lower filtration part that forms a lower filtration layer by filling a lower filtration material of less than .8, and generates an upward flow with the filtration target water supplied to the filtration tank, and the solid in the filtration target water This is a method for washing a solid-liquid separation device that separates the minute components to produce filtered water, and jets bubbles to the upper filtration precipitation layer to swirl the upper filter material, resulting in disturbance of the upper filter material. S for separating the SS captured by the upper filter medium A separation step, a stationary step of standing until the SS separated by the SS separation step settles on the upper screen, and the filtration tank corresponding to a height between the lower screen and the bottom of the filtration tank And a discharging step of discharging the tank water inside.

  According to this invention, the lower filtration layer is formed by filling the lower space between the lower screen and the bottom of the filtration tank with the lower filter material having a specific gravity of 0.1 or more and less than 0.8. The SS retention around the surface layer in the lower filtration layer suppresses clogging of the lower screen and eliminates the need for cleaning the lower screen, so that a high SS removal rate can be easily maintained. it can.

FIG. 1 is a schematic diagram showing a configuration of a solid-liquid separation device according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing a configuration of a filtration processing system including the solid-liquid separation device shown in FIG. FIG. 3 is a diagram illustrating a configuration of the upper filter medium illustrated in FIG. 1. FIG. 4 is a diagram illustrating a configuration of the lower filter medium illustrated in FIG. 1. FIG. 5 is a schematic diagram showing a state at the time of the filtration process in the solid-liquid separation process by the solid-liquid separation apparatus shown in FIG. FIG. 6 is a schematic diagram illustrating a state at the time of a filter medium cleaning process in the solid-liquid separation process performed by the solid-liquid separation apparatus illustrated in FIG. 1. FIG. 7 is a schematic diagram showing a state of standing after washing in the solid-liquid separation process by the solid-liquid separation device shown in FIG. FIG. 8 is a schematic diagram showing a state at the time of the washing and discharging process in the solid-liquid separation process by the solid-liquid separation apparatus shown in FIG. FIG. 9 is a flowchart showing a cleaning process procedure of the solid-liquid separator shown in FIG. FIG. 10 is an explanatory diagram for explaining an application example of the embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings.

(overall structure)
FIG. 1 is a schematic diagram showing a configuration of a solid-liquid separation device according to an embodiment of the present invention. FIG. 2 is a plan view schematically showing a configuration of a filtration processing system including a solid-liquid separation device. As shown in FIG. 1, the solid-liquid separation device 1 captures and separates the solid content that is SS in the supplied filtration target water W <b> 1 and discharges the filtered water from which the solid content has been separated as treated water. A filtration tank 10 is provided.

In the filtration tank 10, the upper screen 2 is arranged at the upper part and the lower screen 3 is arranged at the lower part. The upper space between the upper screen 2 and the lower screen 3 is filled with an upper filter material 4a such as a floating filter material having a specific gravity of 0.8 or more and less than 1.0 to form an upper filtration precipitation layer 4. . On the other hand, the lower space between the lower screen 3 and the bottom of the filtration tank 10 is filled with a lower filter material 5a having a specific gravity of 0.1 or more and less than 0.8 to form the lower filter layer 5. Upper screen 2 may be any structure that the upper filtering material 4a does not pass through the lower screen 3 may be a structure in which the upper filtering material 4a and the lower filtering material 5a does not pass. In addition, the upper screen 2, the lower screen 3, and the upper filtration precipitation layer 4 are upper filtration precipitation parts, and the lower screen 3 and the lower filtration layer 5 are lower filtration parts. That is, the lower screen 3 is used as both an upper filtration precipitation part and a lower filtration part.

  A supply unit 12 is connected to the bottom of the filtration tank 10. Further, the supply unit 12 is connected to the distribution tank 11. As for the distribution tank 11, the raw | natural water tank 100 shown in FIG. 2 is connected to an upstream, and the filtration target water W1 is supplied. As shown in FIG. 2, the distribution tank 11 distributes the filtration target water W1 to the plurality of filtration tanks 10 (10a to 10d) via the plurality of supply units 12 (12a to 12d). As shown in FIG. 1, the supply unit 12 is provided with an on-off valve V <b> 1 to control the supply of the filtration target water W <b> 1 to the filtration tank 10. Further, a water level sensor 12 a that detects the water level of the filtration target water W <b> 1 supplied to the supply unit 12 is provided at the upper part of the supply unit 12.

  Furthermore, on the side of the upper part of each filtration tank 10, on the upper part of the upper screen 2, as shown in FIG. 2, as shown in FIG. 10a to 10d), and the filtered water W2 from each of the filtration tanks 10a to 10d is discharged at a time. In addition, although each filtration tank 10a-10d is arrange | positioned adjacently, between each filtration tank 10a-10d is isolated by the vertical wall, and the filtrate W2 which overflows from each filtration tank 10a-10d is only to the collection tank 15. Discharged.

  In addition, the bottom of the filtration tank 10 is provided with a discharge pipe 17 for discharging the cleaning waste water W3 at the time of cleaning. An on-off valve V3 is provided in the middle of the discharge pipe 17, and controls the discharge of the cleaning waste water W3 from the filtration tank 10 during the downward cleaning of the filtration tank 10. A pump 14 is provided downstream of the on-off valve V3, and the pump 14 forcibly discharges the cleaning waste water W3.

  Further, an air bubble generation unit 16 a provided at the tip of the air pipe 16 is disposed on the upper side of the lower screen 3 and on one side inside the filtration layer 10. The air pipe 16 is connected to the compressor 13 via the on-off valve V2. Before the on-off valve V3 is opened and the filtration tank 10 is washed downward, the on-off valve V2 is opened, the compressed air supplied from the compressor 13 is ejected from the bubble generation unit 16, and swirls into the upper filtration sedimentation layer 4. By generating a flow and perturbing the upper filter medium 4a, the SS captured by the upper filter medium 4a is peeled off.

  In addition, a bubble generation unit 16 a ′ provided at the tip of the air pipe 16 ′ is disposed at the bottom of the filtration tank 10. The air pipe 16 ′ is connected to the compressor 13 via the on-off valve V2 ′. While the filtration tank 10 is being washed downward, the on-off valve V2 ′ is intermittently opened, and the compressed air supplied from the compressor 13 is intermittently ejected from the bubble generation unit 16a ′, mainly disturbing the lower filter medium 5a. The SS captured by the lower filter medium 5a is peeled off.

  In addition, as shown in FIG. 3, the upper filter medium 4a is a cylindrical floating filter medium, and captures SS by the precipitation effect. This sedimentation effect is intended to capture SS by increasing the sedimentation area and increasing the sedimentation effect by forming a long filtration path through which the water to be filtered passes through a plurality of cylinders or between filter media. . As shown in FIG. 3, the filtration path L2 through the plurality of upper filtration media 4a is, for example, about twice as long as the filtration pathway L1 not through the upper filtration media 4a. The longer filtration path L2 means that the sedimentation area is equivalently increased in the SS removal process. For example, the sedimentation area is increased about twice, and the SS removal rate is increased. As a result, the filter tank that achieves the same SS removal rate can be made compact.

  As described above, the tubular floating filter has a specific gravity of 0.8 or more and less than 1.0, preferably 0.9, and has a shape of, for example, a diameter of 5.5 mm and a length of 7 mm. Although this cylindrical floating filter medium is lighter than the filtration target water, it has the same specific gravity as the filtration target water, and therefore moves together with the filtration target water so that the filter medium does not flow out by the upper screen 2 and the lower screen 3. I have to. The cylindrical floating filter medium should just be a material which does not chemically react with water to be filtered. In particular, alkali-resistant materials, acid-resistant materials, wear-resistant materials, and non-water-absorbing materials are preferable. In addition, the thickness of the upper filtration precipitation layer 4 formed of the cylindrical floating filter medium is, for example, 70 to 100 cm. The upper filtration sedimentation layer 4 formed by this cylindrical floating filter medium is preferably a high void layer having a void ratio of 90% or more, which is a combination of the voids in the cylinder and the space between the filter media, and the SS removal rate is 80%. Has a high degree of ability. Moreover, the upper filter medium 4a is cylindrical and has a larger specific surface area than the lower filter medium 5a.

  On the other hand, the lower filter medium 5a is, for example, a windmill type floating filter medium as shown in FIG. The lower filtration layer 5 formed by this windmill type floating filter medium mainly restrains SS in the lower surface layer. As described above, the windmill type floating filter medium has a specific gravity of 0.1 or more and less than 0.8, preferably 0.7, for example, a size of 6 mm × 6 mm × 4 mm. Moreover, the windmill type floating filter material should just be a material which does not chemically react with water to be filtered. In particular, alkali-resistant materials, acid-resistant materials, wear-resistant materials, and non-water-absorbing materials are preferable. Since the windmill type floating filter medium has a large buoyancy, the upward movement is suppressed by the lower screen 3 that functions as an upper screen for the lower filter medium 5a. However, conversely, for example, when a downward flow occurs during cleaning, it follows downward and spreads and spreads about 1.5 times the thickness of the lower filtration layer 5, but it reaches the lower part further. There is no. Therefore, there is no need to provide a lower screen for the lower filter material 5a, and the depth from the bottom of the filtration layer 10 to the lower screen 3 is set to 1.5 times the thickness of the lower filtration layer 5 or more. While the impurities, SS and the like are discharged, the lower filter medium 5a develops but does not flow out of the filter tank 10. In addition, the thickness of the lower filtration layer 5 formed of the windmill type floating filter medium is, for example, 20 cm. The lower filtration layer 5 formed of this windmill type floating filter medium is a medium void layer with a porosity of about 50%, which combines the spaces between the filter media, and an SS removal rate of about 60 to 70%.

  By forming such two filtration layers of the upper filtration precipitation layer 4 and the lower filtration layer 5 in the filtration tank 10 and flowing the filtration target water W1 as an upward flow, mainly on the surface of the lower filtration layer 5 SS is detained, SS is roughly removed, and the filtration target water that has passed through the lower filtration layer 5 further captures fine SS that has passed through the lower filtration layer 5 due to the precipitation effect of the upper filtration precipitation layer 4, and has passed through the filtration target. Water is discharged out of the filtration tank 10 as filtered water W2. Here, the lower screen 3 provided in order to prevent the upper filter material 4a constituting the upper filtration precipitation layer 4 from flowing out is made of SS such as hair and paper by the lower filtration layer 5 formed at the lower part of the lower screen 3. Therefore, a relatively large SS is difficult to reach the lower screen 3 and clogging is less likely to occur. Conventionally, the lower screen 3 is clogged, and the disadvantage of the conventional upper filtration precipitation layer that the filtration capacity does not return even if backwashing is eliminated. Further, it is not necessary to perform manual cleaning using a brush or the like for eliminating this clogging, which was necessary in the past. As a result, it is possible to realize a solid-liquid separation apparatus that can be easily maintained while ensuring a high SS removal rate.

  During filtration, the control unit C opens the on-off valve V1, closes the on-off valves V2, V2 ', and V3, introduces the filtration target water W1 into the filtration tank 10, and generates an upward flow. The filtered water is discharged from the upper part of the tank 10. Further, the control unit C closes the on-off valves V1, V2 ′, V3 and opens the on-off valve V2 at the start of cleaning of the filter medium, and generates air bubbles from the air bubble generating unit 16a by the compressed air from the compressor 13. The upper filter medium 4a is swirled and disturbed, and the SS is peeled off. Furthermore, at the time of washing and discharging, the control unit C closes the on-off valves V1, V2, V2 ′, opens the on-off valve V3, drives the pump 14 to wash the water to be filtered in the filtration tank 10 containing SS. Forced discharge as drainage W3. Note that the control unit C pulsates bubbles by opening the on-off valve V2 ′ once or intermittently for several seconds after the start of forced drainage with the on-off valve V3 opened, and mainly lower filter medium. Encourage equal development due to disturbance of 5a.

(Solid-liquid separation process)
Next, with reference to FIGS. 5-8, the solid-liquid separation process of the filtration object water by the filtration tank 10 is demonstrated. First, as shown in FIG. 5, when the on-off valve V <b> 1 is opened, a target to be filtered from the distribution tank 11 to the filtration tank 10 from the lower part of the filtration tank 10 through the supply unit 12 by natural flow using the water level difference. Water W1 is introduced and an upward flow is generated. That is, in the filtration target water W1, SS is sequentially captured by the lower filtration layer 5 and the upper filtration precipitation layer 4, and the filtered water W2 from which SS has been removed is discharged from the filtration tank 10 to the collecting tank 15. In the lower filtration layer 5, SS is mainly retained in the lower surface layer, and in the upper filtration precipitation layer 4, fine SS is captured by the precipitation effect in the cylinder of the upper filtration material 4a.

  Then, with the acceleration | stimulation of capture | acquisition of SS in the lower filtration layer 5 and the upper filtration precipitation layer 4, the filtration loss head of the lower filtration layer 5 and the upper filtration precipitation layer 4 increases, and the water surface of the supply part 12 rises. When the filtration loss head reaches a predetermined value, a cleaning process is performed. This cleaning process is divided into a filter medium cleaning process and a cleaning discharge process. Whether or not the filtration loss head has reached a predetermined value is determined based on the water level detection result by the water level sensor 12a or the like.

  As shown in FIG. 6, the filter medium cleaning process first closes the on-off valve V1, opens the on-off valve V2, and sends compressed air from the compressor 13 to the bubble generating unit 16a through the air pipe 16, thereby generating bubbles. Erupt. This bubble causes the upper filter medium 4a to swirl and flow to cause SS (4b) to peel off from the upper filter medium 4a. Thereafter, the generation of bubbles is stopped and left standing (FIG. 7). When the peeled SS (4b) settles by this standing, the standing time is taken as long as possible to promote the sedimentation. In particular, since the SS (4b) captured by the upper filter medium 4a is small, the settling speed is slow. Therefore, the SS (4b) captured by the upper filter medium 4a is settled in the vicinity of the lower screen 3 for a certain period of time. Time is preferred. In addition, since SS (5b) adhering to the lower filter medium 5a is relatively large, the sedimentation speed is high, and the SS (5b) can be easily peeled off by the washing and discharging process described later. For 5a, this filter medium cleaning treatment is not essential. Moreover, although the upper filter material 4a has a large SS removal rate, the amount of captured SS is smaller than that of the lower filter material 5a.

  Thereafter, as shown in FIG. 8, a cleaning and discharging process is performed. In this washing and discharging process, the on-off valve V3 is opened and the pump 14 is driven to forcibly discharge the filtration target water W1 stored in the filtration tank 10. By this forced discharge, a downward flow is generated in the filtration tank 10, and the peeled SS (4b) descends downward. Further, the lower filter medium 5a diffuses and expands, and the SS (5b) also peels off at the same time, and is lowered and discharged downward. This forced discharge amount is an amount corresponding to a depth d2 from the lower screen 3 to the bottom of the filtration tank 10 having a height of 1.5 times or more the thickness d1 of the lower filtration layer 5. This is because the diffusion / development of the lower filtration layer 5 is 1.5 times thick, and this layer contains a large amount of SS (4b, 5b) separated by washing. In addition, when not performing a filter medium washing | cleaning process, most SS has adhered to the lower filter medium 5a, and it is sufficient to wash | clean the lower filter medium 5a which is easy to get dirty by spreading | diffusion and expansion | deployment of the lower filter medium 5a. it can. In addition, when a lot of minute SS is restrained in the upper filter medium 4a, it is necessary to also discharge the upper part of the lower screen 3, increase the opening time of the on-off valve V3 or increase the number of washing, Drain the upper cleaning waste water containing micro SS.

  Further, during the cleaning and discharging process, as described above, the on-off valve V2 ′ is opened once or intermittently for a few seconds to cause the bubbles 13b to be ejected in a pulsed manner from the bubble generating unit 16a ′. Encourage uniform deployment due to disturbance of the filter medium 5a.

  Conventionally, the filtered water W2 is supplied from the upper part of the filtration tank 10 to this washing and discharging process, and all the tank water below the lower screen 3 is replaced with the filtered water W2. However, the replacement amount according to this embodiment is filtered. Since it is a small amount corresponding to the depth from the bottom of the tank 10 to the lower screen 3, washing waste water is reduced and the filtrate recovery rate can be improved.

  Moreover, conventionally, in the high-speed filtration apparatus using only the lower filtration layer 5 formed of a windmill type filter medium, the thickness of the lower filtration layer 5 was 60 to 80 cm. However, the lower filtration layer 5 of this embodiment is Is as thin as 20 cm. The decrease in the SS removal due to the thinning can be compensated for by the upper filtration precipitation layer 4, and the apparatus of this embodiment has a filtration capacity equal to or higher than that of the conventional apparatus. Further, since the height of the lower filtration layer 5 is reduced, the height to the lower screen 3 is also reduced, so that it is possible to significantly reduce the amount of waste water during washing or the amount of filtrate when using filtrate during washing. it can.

(Cleaning procedure)
The cleaning process procedure by the control unit C described above will be described with reference to the flowchart shown in FIG. First, the controller C determines whether or not the filtration loss head has reached a predetermined value based on the water level detected by the water level sensor 12a (step S101). When the filtration loss head does not reach the predetermined value (step S101, No), this determination is repeated, and when the filtration loss head reaches the predetermined value (step S101, Yes), the on-off valve V1 is closed ( Step S102) and the filtration process is stopped.

  Thereafter, the on-off valve V2 is opened from the closed state (step S103), the bubbles are ejected from the bubble generation unit 16a, the upper filter medium 4a is disturbed by the swirling flow, and the SS (4b) of the upper filter medium 4a is peeled off. Thereafter, when a predetermined time ΔT1 that is sufficient time for the SS (4b) to peel is elapsed (Yes in Step S104), the on-off valve V2 is closed (Step S105), and the SS (4b) of the upper filter medium 4a is closed. Finish the peeling process. If the predetermined time ΔT1 has not elapsed (No in step S104), this determination process is repeated until the predetermined time ΔT1 has elapsed.

  Further, when a predetermined time ΔT2 that is a standing time sufficient for the SS (4b) thus peeled to settle on the lower screen 3 has elapsed (step S106, Yes), the on-off valve V3 is opened, and the pump 14 is driven (step S107), the tank water in the filtration tank 10 is lowered, and forced discharge is started. If the predetermined time ΔT2 has not elapsed (No in step S106), this determination process is repeated until the predetermined time ΔT2 has elapsed.

  After that, when a predetermined time ΔT3, for example, several seconds have passed (step S108, Yes), the on-off valve V2 ′ is intermittently opened (step S109), and bubbles are generated along with the uniform expansion of the lower filter medium 5a by the downward flow. Separation of SS (5b) is promoted by the disturbance of the lower filter medium 5a due to the ejection of the pulsed bubbles 13b from the portion 16a ′. Thereafter, when a predetermined time ΔT4, for example, several seconds have elapsed (step S110, Yes), the on-off valve V2 ′ is closed (step S111), and the bubble ejection is stopped. Note that, when the predetermined time ΔT3 has not elapsed (step S108, No) and when the predetermined time ΔT4 has not elapsed (step S110, No), this determination process is repeated until the predetermined time ΔT3, ΔT4 has elapsed.

  Thereafter, it is determined whether or not the forced discharge at the depth d2 has ended (step S112). When the forced discharge at the depth d2 has ended (step S112, Yes), the on-off valve V3 is closed and the pump is discharged. 14 is stopped, the on-off valve V1 is opened (step S113), preparation for resuming the filtration process is performed, and this process ends. If the forced discharge for the depth d2 does not end (No in step S112), this determination process is repeated until the forced discharge for the depth d2 ends.

  Conventionally, the cleaning waste water W3 is discharged by natural flow using the difference in water level in the filtration tank 10, but in this embodiment, the pump 14 is forcibly discharged. When the cleaning wastewater is forcibly discharged using the pump 14, the discharge speed (m / s) in the discharge pipe 17 can be increased as compared with the natural flow discharge. The size of the cleaning apparatus can be reduced.

  Moreover, although the solid-liquid separation apparatus 1 mentioned above is used as an alternative of a sedimentation basin, you may provide this filtration layer 10 in the existing sedimentation basin. Even in this case, when the pump 14 is used, the number of existing sedimentation basins to be used can be reduced. For example, as shown in the upper diagram of FIG. 10, conventionally, three sedimentation basins 101 to 103 are used, the filtration target water W1 is solid-liquid separated in the sedimentation basin 101, and the washing wastewater W3 is naturally separated by using the water level difference. The washed waste water W3 discharged to the settling basin 102 was pumped up and discharged to the settling basin 103 to precipitate SS. In this case, the amount of the washing waste water W3 discharged to the settling basin 102 functioning as a temporary receiving tank has a small effective capacity of the settling ground 102 in order to ensure a difference in water level. On the other hand, in the application example of this embodiment, as shown in the lower diagram of FIG. 10, the filtration tank 10 is disposed in the settling basin 101 and the washing waste water W3 from the filtration tank 10 is forcibly discharged by the pump 14. Since it is discharged directly to the sedimentation basin 103, the sedimentation basin 102 which is a temporary receiving tank is not required, and the sedimentation basin 103 can be effectively used as a similar sedimentation basin.

  In addition, although the upper filter material 4a and the lower filter material 5a which were mentioned above were different filter media, not only this but the same filter media may be sufficient, and the shape and property of a filter media are arbitrary. For example, both the upper filter medium 4a and the lower filter medium 5a may be windmill type filter media. In short, it is only necessary that the lower filter medium 5a has a specific gravity of 0.1 or more and less than 0.8 and does not flow easily during cleaning.

DESCRIPTION OF SYMBOLS 1 Solid-liquid separator 2 Upper screen 3 Lower screen 4 Upper filtration precipitation layer 4a Upper filter material 4b SS
5 Lower filtration layer 5a Lower filtration material 5b SS
DESCRIPTION OF SYMBOLS 10 Filtration tank 11 Distribution tank 12 Supply part 12a Water level sensor 13b Bubble 15 Collecting tank 16, 16 'Air piping 16a, 16a' Bubble generation part 17 Discharge pipe V1, V2, V2 ', V3 On-off valve W1 Filtration target water W2 Filtration Water W3 Wash drain

Claims (6)

A solid-liquid separation device that generates an upward flow from the filtration target water supplied to the filtration tank, separates the solid content in the filtration target water, and generates filtered water,
It has an upper screen and a lower screen, and the upper space between the upper screen and the lower screen is filled with an upper filter material having a specific gravity of 0.8 or more and less than 1.0 to form an upper filtration precipitation layer. An upper filtration sedimentation section,
A lower filtration part that forms a lower filtration layer by filling a lower space between the lower screen and the bottom of the filtration tank with a lower filtration material having a specific gravity of 0.1 or more and less than 0.8;
A solid-liquid separation device comprising: Equipped with a discharge pipe for discharging washing wastewater at the bottom of the filtration tank,
The height between the lower screen and the bottom of the filtration tank is such that the lower filter material expands downward corresponding to the specific gravity when the discharge pipe is opened and washing is performed to generate a downward flow. The solid-liquid separator according to claim 1, wherein the thickness is equal to or greater than the thickness of the solid-liquid separator.   The solid-liquid separator according to claim 1, wherein the upper filter medium is a floating filter medium having a specific surface area larger than that of the lower filter medium.   The solid-liquid separator according to claim 3, wherein a height between the lower screen and a bottom of the filtration tank is 1.5 times or more a thickness of the lower filtration layer. A discharge pipe for discharging washing wastewater to the bottom of the filtration tank;
A pump provided in the discharge pipe for sucking and discharging the cleaning waste water;
The solid-liquid separation device according to any one of claims 1 to 4, further comprising: The filtration tank has an upper screen and a lower screen, and the upper space sandwiched between the upper screen and the lower screen is filled with an upper filter material having a specific gravity of 0.8 or more and less than 1.0. An upper filtration sedimentation section that forms a sedimentation layer;
A lower filtration part that forms a lower filtration layer by filling a lower space between the lower screen and the bottom of the filtration tank with a lower filtration material having a specific gravity of 0.1 or more and less than 0.8;
A washing method of a solid-liquid separation device that generates an upward flow by the filtration target water supplied to the filtration tank, and separates the solid content in the filtration target water to generate filtered water,
An SS peeling step for blowing bubbles to the upper filtration sedimentation layer to swirl the upper filter medium, and peeling SS captured by the upper filter medium due to disturbance of the upper filter medium;
A stationary step of standing until the SS peeled by the SS peeling step settles on the upper screen;
A discharge step of discharging the tank water in the filtration tank corresponding to the height between the lower screen and the bottom of the filtration tank;
A method for cleaning a solid-liquid separator, comprising:

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