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Timestamp: 2017-10-17 08:03:17
Document Index: 758282963

Matched Legal Cases: ['art, 33', 'art,\n110', 'arts 33', 'art 33', 'arts 33', 'art 33', 'art 110', 'art 110', 'arts 110', 'art 110', 'art 110']

Filtrate monitoring device, and filtrate monitoring system - Hirata Corporation
United States Patent 8142660
Murakami, Seigo (Kumamoto, JP)
Hirakawa, Takenori (Kumamoto, JP)
Iseri, Takafumi (Kumamoto, JP)
12/445350
210/86, 210/87, 210/93, 210/96.2, 210/644
B01D35/00; C02F1/44
210/637, 210/95
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20100126940 UNDERWATER PLASMA PROCESSING APPARATUS AND SYSTEM AND METHOD FOR PROCESSING BALLAST WATER OF SHIP USING THE SAME 2010-05-27 Ryu et al. 210/744
JP1993215664 August, 1993
JP1994035948 May, 1994
JP1995086457 September, 1995
JP1996119961 June, 1996
JP1996252440 October, 1996
JP1998024283 January, 1998
JP2000046721 February, 2000 WATER-CONTROLLING DEVICE
JP2000046721A 2000-02-18 WATER-CONTROLLING DEVICE
JP2000088841A 2000-03-31 WATER QUALITY MEASURING DEVICE AND WATER QUALITY MONITORING SYSTEM
JP2000155088A 2000-06-06 DRAINING METHOD FOR SAMPLE LIQUID AND WASHING LIQUID IN PARTICLE DIAMETER DISTRIBUTION MEASURING DEVICE BY LIGHT SCATTERING METHOD
JP2000342937 December, 2000 DEVICE AND METHOD FOR DETECTING MEMBRANE DAMAGE OF HOLLOW FIBER MEMBRANE FILTER APPARATUS
JP2000342937A 2000-12-12 DEVICE AND METHOD FOR DETECTING MEMBRANE DAMAGE OF HOLLOW FIBER MEMBRANE FILTER APPARATUS
JP2002082025A 2002-03-22 DISSOLVING DEVICE, ANALYZER AND DISSOLVING METHOD
JP2004216311A 2004-08-05 METHOD AND APPARATUS FOR CHECKING HOLLOW FIBER MEMBRANE MODULE FOR DEFECT
JP2005013992A 2005-01-20 SAFETY TESTING METHOD FOR HOLLOW FIBER MEMBRANE MODULE
JPH05215664A 1993-08-24
JPH0686457B2 1994-11-02
JPH0811996A 1996-01-16
JPH08252440A 1996-10-01
JPH0635948A 1994-02-10
JPH1024283A 1998-01-27
1. A filtrate water monitoring apparatus which monitors filtrate water discharged from a membrane filtration water-purifying apparatus, comprising: physical detection means for utilizing or detecting a physical phenomenon which varies depending on behavior of particles in the filtrate water flowing in a branch filtrate water pipe line system (hereinafter, called “particles in flowing water”) wherein the physical detection means is connected to the branch filtrate water pipe line system branching in order to sample some of the filtrate water as sample water from a filtrate water pipe line system connected to an outlet of the membrane filtration water-purifying apparatus; a filtrate water observation cell which is arranged downstream of the physical detection means in the branch filtrate water pipe line system and has a flow channel for letting the filtrate water pass through inside thereof; and image detection means for shooting an image in filtrate water flowing in the flow channel of the filtrate water observation cell and for identifying impurities included in the filtrate water.
4. The filtrate water monitoring apparatus according to claim 1, comprising: an openable and closable valve disposed between the physical detection means and the filtrate water observation cell in the branch filtrate water pipe line system such that the filtrate water flows into the filtrate water observation cell when the physical detection means detects a greater number of particles in the flowing water than a predetermined number.
6. The filtrate water monitoring apparatus according claim 1, comprising: physical concentration means for increasing density of the particles in the flowing water that flows into the filtrate water observation cell, the physical concentration means disposed between the physical detection means and the filtrate water observation cell in the branch filtrate water pipe line system.
7. The filtrate water monitoring apparatus according to claim 1 wherein the filtrate water observation cell has an observation bath through which flow of the filtrate water is observed in the flow channel, and a plurality of filtrate water observation cells are arranged in series along the branch filtrate water pipe line system.
8. The filtrate water monitoring apparatus according to claim 1 wherein the filtrate water observation cell has an observation bath through which flow of the filtrate water is observed in the flow channel, and a plurality of observation baths are arranged in series along the flow channel.
14. A filtrate water monitoring system comprising: a plurality of membrane filtration water-purifying apparatuses and a filtrate water monitoring apparatus that monitors filtrate water filtrated through each of the membrane filtration water-purifying apparatuses, the filtrate water monitoring system comprising: filtrate water pipe line systems connected respectively to outlets of the plurality of membrane filtration water-purifying apparatuses; branch filtrate water pipe line systems respectively connected to the filtrate water pipe line systems, the branch filtrate water pipe line systems sampling part of the filtrate water as sample water from the filtrate water pipe line systems; physical detection means for utilizing or detecting a physical phenomenon which varies depending on behavior of particles in the filtrate water flowing in the branch filtrate water pipe line systems wherein the physical detection means is connected to the branch filtrate water pipe line systems branching in order to sample some of the filtrate water as sample water from the filtrate water pipe line systems connected to the outlets of the membrane filtration water-purifying apparatuses; a filtrate water observation cell connected to a midpoint of at least one pipe line system in the branch filtrate water pipe line systems, and the filtrate water observation cell having a flow channel in which the filtrate water flows; and image detection means for shooting an image in filtrate water flowing in the flow channel of the filtrate water observation cell, and for identifying particles in the flowing water included in the filtrate water, wherein the filtrate water observation cell has an observation bath through which flow of the filtrate water is observed in the flow channel.
15. The filtrate water monitoring system according to claim 14 wherein the observation bath has a step to decrease a cross-sectional area of the flow channel along the flow channel.
16. The filtrate water monitoring system according to claim 14 wherein a porous plate with pores is disposed so as to block the flow channel.
4a. outgoing pipe, 4b. return pipe,
32a, 32b. flange, 33. orifice flange,
33a. straight pipe part, 33b, 33c. flange part,
110a, 110b, 110c, 110d. observation bath,
160. turbidity meter, 160a. fine-particle counter,
The branch filtrate water pipe line system 4 is made to branch from the filtrate water pipe line system as follows. That is, as shown in FIG. 2 in an enlarged manner, a part of the pipe near the connected portion of the filtrate water pipe line system 32 to the membrane filtration water-purifying apparatus 30 is cut off, and an orifice flange 33 is instead inserted therein to be connected and coupled in a liquid-tight manner. The orifice flange 33 is built into the filtrate water pipe line system 32 such that flange parts 33b and 33c are integrally provided at both ends of a short straight pipe part 33a, and these flange parts 33b and 33c are coupled with flanges 32a and 32b respectively formed integrally at the opposing ends of the filtrate water pipe line system 32 to the both ends of the cut-off part by means of fastening means such as bolts.
An orifice 34 is provided inside the straight pipe part 33a, and a difference in pressure is generated in a fluid (filtrate water) flowing inside the filtrate water pipe line system 32 before and after the orifice 34. Then, an inlet end to an outgoing pipe 4a of the branch filtrate water pipe line system 4 is connected to the high-pressure side upstream of the orifice 34, and an outlet end from a returning pipe 4b of the branch filtrate water pipe line system 4 is connected to the low-pressure side downstream. An outlet end of the outgoing pipe 4a and an inlet end of the returning pipe 4b are connected to the filtrate water sampling/image shooting unit 2. The filtrate water on the high-pressure side upstream of the orifice 34 is guided to the filtrate water sampling/image shooting unit 2 through the outgoing pipe 4a, and filtrate water which is excess there is returned to the low-pressure side downstream of the orifice 34 through the returning pipe 4b. In this way, the filtrate water sampling/image shooting unit 2 in Embodiment 1 can be conveniently incorporated and established into the existing membrane filtration water-purifying apparatus 30 only by connecting the orifice flange 33 of the branch filtrate water pipe line system 4 in a liquid tight manner to the cut-off part of the filtrate water pipe line system 32. In addition, a throttle nozzle may be utilized instead of the orifice 34. The water supply pipe line system 31 for natural water is connected to the inlet of the membrane filtration water-purifying apparatus 30.
FIG. 3 shows a detailed configuration of the filtrate water monitoring apparatus 1 in Embodiment 1. Some of the filtrate water is taken as a sample water upstream of the orifice flange 33, and the filtrate water is guided to the filtrate water sampling/image shooting unit 2 of the filtrate water monitoring apparatus 1 through the outgoing pipe 4a of the branch filtrate water pipe line system 4. The filtrate water sampling/image shooting unit 2 is constituted of mainly a filtrate water observation plate 10 and an optical device 20. In the filtrate water sampling/image shooting unit 2, a required quantity of sample water is made to branch by a first three-direction connector 6 to be guided to a second three-direction connector 8 through a pipe line 6a and a needle valve 7. The sample water is further made to branch through the second three-direction connector 8 to be guided to the filtrate water observation plate (filtrate water observation cell) 10 provided in the middle of the pipe line 8a through a pipe line 8a. Pumps 11 and 12 are respectively set on the pipe lines as the pipe line 8a at the inlet side and the outlet side of the filtrate water observation plate 10. Since the pump 11 only has to take care of a pressure loss caused by flowing of filtrate water up to the pump 11 and a pressure loss caused by flowing of filtrate water from the pump 11 up to the pump 12, a required output power by the pump 11 may be relatively small, and a pressure increase in the filtrate water inside the filtrate water observation plate 10 is suppressed to be low, thereby avoiding unbearable pressure inside the filtrate water observation plate 10. This is especially advantageous for a case where the filtrate water observation plate 10 is formed by bonding two glass plates. Here, only one filtrate water observation plate 10 is explained by way of example. However, two or more filtrate water observation plates 10 may be connected in series along the branch filtrate water pipe line system 4, and a filtrate water observation cell is constituted of one or more filtrate water observation plates 10.
Excess filtrate water (unused sample water) which does not flow in a direction of the filtrate water observation plate 10 through the first three-direction connector 6, i.e., in a direction of the pipe line 6a is returned to the low pressure side downstream of the orifice 34 of the orifice flange 33 through the returning pipe 4b. A flow rate of the excess filtrate water is measured by a flow meter 5 disposed at an upstream part of the returning pipe 4b, and apertures of cutoff valves 13 and 14 respectively provided in the middle of the outgoing pipe 4a and in the middle of the returning pipe 4b are appropriately adjusted in accordance with a flow rate to be measured. The filtrate water discharged from the pump 12 and the excess filtrate water which does not flow in the direction of the filtrate water observation plate 10 through the second three-direction connector 8, i.e., in the direction of the pipe line 8a flow into each other to be wasted as drain water. Because new filtrate water always flows through the filtrate water observation plate 10 in this way, it is possible to always grasp a current situation of the filtration film of the membrane filtration water-purifying apparatus 30.
A deforming device 9 is provided upstream of the filtrate water observation plate 10 in the pipe line 8a. The deforming device 9 is a device to remove bubbles included in filtrate water. Thus, since the filtrate water flowing inside an observation bath 16 of the filtrate water observation plate 10 does not include foam, image shooting of impurities included in the filtrate water, which shows a result of a damage to the filtration film, and identifying the impurities are more precisely conducted such that it is possible to grasp the situation of the damage to the filtration film more accurately.
In the optical device 20, a digital camera 22 shoots an image in the filtrate water to be observed through an objective lens 21, and the digital camera 22 transmits the image information taken as an image to the image analysis unit 3. The digital camera 22 has an illumination 22a that illuminates an object to be observed. The image analysis unit 3 is constituted of mainly a computer. When the computer receives the image information output from the optical device 20, the image analysis unit 3 identifies shapes, sizes, and the number of impurities in the image information by image processing, and compares those with an image pattern stored in its storage unit to analyze and identify what the impurities included in the filtrate water are. Because the work for analyzing/identifying impurities by the computer is performed while the image thereof is displayed and enlarged on the display of the computer, it is possible for a human to confirm the identification work. Further, by networking the optical device 20 and the computer, it is possible to perform the work for analyzing/identifying the impurities even at a point distant from the optical device 20, which makes it possible to remotely monitor filtrate water. The impurities included in the filtrate water are identified and the number of the impurities are grasped in this way such that it is possible to confirm the situation of damage to the filtration film installed inside the membrane filtration water-purifying apparatus 30.
The impurities in the filtrate water easily pool on the abyss side of the step 23 in the observation bath 16, and their planar shapes can be observed via the upper glass plate 102 (FIGS. 6A to 6D). The step 23 is different from the step 23 as shown in FIG. 4B such that the step 23 of FIGS. 6A to 6D is formed into a V-shape in the plan view so as not to dam the flow of the filtrate water, but to let the flow pass through the step 23 partially as the impurities are easily collected in a valley bottom of the V-shape. It is considered that this occurs because water flows along a wall 23a of the step 23 and the flow rate of the filtrate water is accelerated at the valley bottom of the V-shape serving as the final outlet, from which the water flows out. Further, in particular, in the case where a depth of the abyss part 110 is much deeper than a depth on the shallow water side, a flow of water easily stagnates in the lower corner portion of the step 23 (a boundary area between the abyss part 110 and the step 23), and a high-density of impurities easily settle down to gather in the lower corner portion. Therefore, even if the impurity concentration is originally low, the number of impurities gathering in the lower corner portion gradually increases as time goes by, thereby making it easier to confirm the shapes of the impurities by observation via the glass plate 102.
FIGS. 7A to 7D show photographs of an assemble of the filtrate water observation plate 10, show schematically a state in which bead particles 116 assuming as the impurities are gradually gathering in the filtrate water observation plate 10 by the step 23 and the wall 23a thereof, and show schematically abyss parts 110 of 20 μm and 10 μm, respectively, in the filtrate water observation plates 10.
FIG. 8 is a schematic diagram for explanation of a self-cleaning mechanism 210 for the observation bath 16 and the like of the filtrate water observation plate 10, that can be applied to Embodiment 1. The filtrate water flows in a pipe 120 in a direction of the arrow in the upper side of the drawing. A valve 124 is normally open, and the filtrate water directly flows into the abyss part 110 of the observation bath 16. At that time, a valve 126 toward a branch flow pipe is closed, and the flow is not made to branch. The water flowing into the abyss part 110 flows toward the halfway line along the wall 23a as described above, and flows over the step 23 to flow toward the shallow part side. At this time, the impurities of appropriate sizes are dammed in front of the step 23, and are observed by the optical device 20. The water flowing toward the shallow part side further passes through a distributing water pipe 122, and passes through a valve 134 normally open to be discharged out of the system. At this time, a valve 132 toward the side of a bypass pipe 130 is closed.
The filtrate water in the pipe 142 made to branch from the filtrate water pipe line system 4 is pressurized so as to compensate for the pressure loss caused so far by the pump 11 and to flow into a filtrate water observation plate 10a. An observation bath 110a is provided in the filtrate water observation plate 10a, and the step 23 (refer to FIG. 7) is provided therein. Impurities of predetermined sizes are blocked and retained in the observation bath 110a by the step 23, and the filtrate water flowing over the step 23 passes through a pipe 144. The filtrate water is further pressurized by the pump 11 to flow into a second filtrate water observation plate 10b. By the step 23 in an observation bath 110b of the filtrate water observation plate 10b as well, impurities in predetermined sizes are retained in the observation bath 110b in the same way, and the filtrate water flowing over the step 23 passes through a pipe 146. The filtrate water is further pressurized by the pump 11 to flow into a third filtrate water observation plate 10c. By the step 23 in an observation bath 110c of the filtrate water observation plate 10c as well, impurities in predetermined sizes are retained in the observation bath 110c in the same way. The filtrate water flowing over the step 23 in the third filtrate water observation plate 10c passes through a pipe 148, to be discharged out of the system. These observation baths 110a, 110b, and 110c are observed for shooting images by the optical device (image shooting means) 20, and are analyzed by the image analysis unit (image analysis means) 3 (refer to FIG. 1). Here, depths of the shallow part sides over the steps 23 in the observation baths 110a, 110b, and 110c are respectively 20 μm, 10 μm, and 2 μm. Accordingly, impurities greater than or equal to 20 μm, 10 μm, and 2 μm can be observed in the respective observation baths 110a, 110b, and 110c. On the other hand, although not shown clearly in the drawing, depths of the abyss sides in the respective observation baths 110a, 110b, and 110c may be respectively adjusted to 50 μm, 20 μm, and 5 μm, and the ranges of particle sizes to be observed can be specified, respectively.
Next, the operations of Embodiment 2 will be described. The sample water in the branched filtrate water pipe line system 4 passes through the throttle valve 140 to flow into the first, second, and third filtrate water observation plates 10a, 10b, and 10c, and an upper-stream filtrate water observation plate among those has a shallow part depth deeper than the step 23. In detail, the depths of the steps/shallow parts in the first, second, and third filtrate water observation plates 10a, 10b, and 10c are respectively 50/20 μm, 20/10 μm, and 5/2 μm, and the sizes of particles to be retained in the observation baths can be limited to a predetermined range by appropriately adjusting the depths of the steps/shallow parts in the filtrate water observation plates. Therefore, greater impurities are remaining in the upper-stream observation bath 110a of the first filtrate water observation plate 10a. Therefore, when the respective observation baths are observed, a magnification of the optical device 20 can be set so as to correspond to the sizes of impurities to be observed, which results in more precise measurement. Further, it is possible to select one of the observation baths 110a, 110b, and 110c to be observed in accordance with the features (sizes, shapes, and the like) of impurities trapped in the respective observation baths 110a, 110b, and 110c, which allows to make the measurement more efficient. Further, in the case where smaller impurities are observed and, for example, in the case where only the third filtrate water observation plate 10c is used, it is possible to cause the filtrate water observation plate 10c to be clogged with larger impurities retained inside the filtrate water observation plate 10c such that the measurement is failed, and therefore, it is possible to prevent such case by using the other filtrate water observation plates. In such a case, an upper-stream filtrate water observation plate functions as a filter for the lower-stream filtrate water observation plate.
Next, a turbidity meter 160 in a laser transmitted light measurement method is provided. The turbidity meter 160 measures a situation of turbidity by measurement using a laser beam before detecting an image of sample water in the flow channel of the branched filtrate water pipe line system 4. It is possible to sense occurrence of damage to the membrane filtration in advance due to the turbidity meter 160. The filtrate water discharged from the turbidity meter 160 flows in a pipe 154 at a flow rate of 100 ml/min, and when the throttle valve 152 is not closed, the filtrate water is directly discharged out of the system. When the throttle valve 152 is closed, the filtrate water passes through the branched pipe line system, and passes through a gate valve 140a to flow into the pump 11. The pump 11 compensates for the pressure loss caused in the upstream, and pressurizes so as to make the filtrate water flow toward a filtrate water observation plate 10d. The filtrate water discharged from the pump 11 flows at approximately 1 ml/min in the pipe 142, and is adjusted to be a favorable flow rate through a throttle valve 140b to flow into an observation bath 110d of the filtrate water observation plate 10d. In the filtrate water observation plate 10d, as described above, the impurities in the filtrate water are accumulated, and images of the impurities are shot by the optical device (image shooting means) 20 for measuring shapes thereof, thereby enabling analysis thereof by the image analysis unit (image analysis means) 3 (refer to FIG. 1). Further, the filtrate water discharged from the filtrate water observation plate 10d is wasted after the observation.
Next, the operations of Embodiment 3 will be described. The sample water in the branched filtrate water pipe line system 4 is always measured by the turbidity meter 160. At this time, the gate valve 140a may be closed, and the optical device 20 may be switched off. When the particle amount in the sample water in the flow channel exceeds a given value and a value of the turbidity meter exceeds a preset value, the gate valve 140a is opened, and the optical device 20 is switched on, which allows to start measuring particles by shooting images. The filtrate water observation plate 10d has the feature of micro-level measurement, and it is considered that the analysis of shot images includes time-consuming work such as reference to the database accumulated in the past, the optical device 20 may be preferably made to operate only for a certain period in this way. That is, it is not necessary to always perform the image measurement.
Further, even if screening measurement with the turbidity meter 160 is performed as a preliminary test, it is not prevented to grasp a special phenomenon such as rupture of the filtration film. A detection level of the turbidity meter 160 can be adjusted such that, when the filtration film is ruptured, an abnormal value is reliably detected by measurement with the turbidity meter 160, and in contrast thereto, when the rupture of the filtration film is not generated, no abnormal value is detected by the measurement with the turbidity meter 160. For detecting the abnormal value in the measurement with the turbidity meter 160, a predetermined threshold may be set, which is appropriately adjustable in the level. That is, provided that the level is set such that it is reliably detected if the filtration film is ruptured and that it can be also detected if there is any possibility of the rupture of the filtration filter, it is possible to detect whether the rupture of the filtration filter occurs or not by more accurate detection means with the filtrate water observation plate 10d against the false alarm.
In this way, provided that screening measurement with the turbidity meter 160 is performed, it is possible to complement the measurement through the filtrate water observation plate 10d, which may be favorable detection means for detecting rupture of the filtration film as a whole. For example, because a large quantity of filtrate water at 100 ml/min can be targeted to measure in screening measurement with the turbidity meter 160, it is possible to more easily prevent errors due to unevenness in sampling. Further, because it is possible to take a sufficient time for measurement through the filtrate water observation plate 10d, it is possible to conduct more precise detection by the filtrate water observation plate 10d.
FIG. 11 is a diagram schematically showing Embodiment 4, which is improvement from Embodiment 3 of FIG. 10. The basic structure of Embodiment 4 is the same as that of Embodiment 2 of FIG. 10, and redundant descriptions will be omitted. In Embodiment 4, a larger quantity of filtrate water at approximately 30 ml/min is made to flow in the pipe 142 made to branch, and a drain pipe 143 with a filter (physical concentration means) 140c is provided in front of the throttle valve 140b. The impurities are concentrated in front of the filter 140c by the filter 140c, and the filtrate water passes through the throttle valve 140b to flow into the observation bath 110d of the filtrate water observation plate 10d. Accordingly, it is possible to pool impurities of an amount required for observation in the observation bath 110d in a shorter time as compared with Embodiment 3 of FIG. 10. As the physical concentration means, not only the filter 140c, but also agglutinated concentrations of impurities by ultrasonic waves from a ultrasonic transducer, adsorptive concentrations of impurities by micro bubbles from a micro bubble generating device, evaporative concentrations of filtrate water by a heater, or the like may be named.
The filtrate water pipe line system 4 is made to branch into a branch line 153 that guides the filtrate water to a fine-particle counter 160a similar to the turbidity meter 160 in Embodiments 3 and 4, and a branch line 143 that guides the filtrate water to the filtrate water observation plates 10a, 10b, and 10c in Embodiment 2. Throttle valves 151a and 151b capable of adjusting a flow rate are arranged as gate valves in the respective pipes 153 and 143. Differently from the cases in Embodiments 3 and 4, the fine-particle counter 160a is not arrayed upstream of the filtrate water observation plates, but arranged in parallel with those.
The throttle valve 151a is always open, to make a considerable quantity of filtrate water at approximately 100 ml/min of filtrate water flowing into the filtrate water pipe line system 4 flow into the pipe 153. The fine-particle counter is capable of always observing to monitor the filtrate water in the same way as the turbidity meter 160. Because a monitoring threshold by the fine-particle counter and the like are substantially the same as in the case of the turbidity meter 160 described above, the details will be omitted. However, differently from Embodiments 3 and 4, the system is made as a parallel system, the types and concentrations of impurities in water to be observed may differ depending on a difference in sampling. On the other hand, because the turbidity meter 160 is independent in parallel, the turbidity meter 160 is capable of producing independent detected results.
The throttle valve 151b is always opened or by a signal corresponding to a measuring result from the fine-particle counter 160a, to guide the filtrate water flowing into the filtrate water pipe line system 4 into the pipe 143. The first, second, and third filtrate water observation plates 10a, 10b, and 10c respectively have depths of 50 μm, 20 μm, and 2 μm as depths at the shallow part sides of the steps 23. Further, the first, second, and third filtrate water observation plates 10a, 10b, and 10c respectively have depths of 100 μm, 20 μm, and 5 μm as depths at the abyss sides of the steps 23. Accordingly, impurities respectively in predetermined sizes are accumulated in the respective observation baths 110a, 110b, and 110c. The shapes of these impurities are taken as images by the optical device (image shooting means) 20, and the images are analyzed by the image analysis unit (image analysis means) 3 (refer to FIG. 1). At this time, in the same way as Embodiment 2, the optical device 20 is provided to be movable along a rail provided in parallel with the observation baths 110a, 110b, and 110c which are arranged in series, and the optical device 20 is made to move in front of the respective observation baths 110a, 110b, and 110c periodically and/or as needed, to take images. Because the one optical device 20 is used in this way, it is possible to avoid a difference in dimension measuring results on the basis of an individual difference in devices.
FIG. 13 shows a table in which sizes and shapes of microorganisms generally included in raw water are organized. As clear from the chart, sizes as impurities differ in accordance with types of microorganisms. Accordingly, types of the respective microorganisms can be further specified by observing shapes of impurities using a plurality of the filtrate water observation plates 10a, 10b, and 10c. For example, when the multiple-stage observation baths of FIG. 12 are used, because Daphnia and Rotifer are 100 μm or more in size, they cannot be put in any observation bath, which cannot be observed. Further, because Closterium sp., Amoeba, and Arcella sp. are approximately 10 μm to 200 μm in size, some of those can be observed in the first observation bath 110a. Further, because Amoeba, Arcella sp., and Giardia are 20 μm or less and 10 μm or more in size in some cases, some of those can be observed in the second observation bath 110b. Then, because Giardia and Cryptosporidium are 5 μm or less and 2 μm or more in some cases, some of those can be observed in the third observation bath 110c. Because these microorganisms can be specifically increased and decreased in filtrate water due to rupture of the filtration film, these microorganisms can be observed as a key to detect rupture of the filtration film. On the other hand, these microorganisms directly have an effect on the quality of water in some cases, and the quality of water can always be observed by detecting and observing these microorganisms, which is greatly useful for quality control. Further, types or amounts of microorganisms to be detected may differ depending on the way of rupturing the filtration film, which makes it possible to simultaneously detect rupture of the filtration film by observing those.
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