Dissolved oxygen consumption measuring device and biochemical oxygen consumption prediction method

Abstract

To provide a dissolved oxygen consumption measuring device capable of efficiently measuring dissolved oxygen consumption of a number of samples and being easily downsized.SOLUTION: A dissolved oxygen consumption measuring device 1 includes: a container 2; a sample liquid supply channel 7 that supplies a sample liquid; an air supply channel 8 that supplies an aeration air; a supply nozzle 10 that supplies a fluid selectively supplied from the sample liquid supply channel 7 and the air supply channel 8 into the container 2; and a dissolved oxygen sensor 4 that detects a dissolved oxygen concentration of the sample liquid supplied to the container 2.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a dissolved oxygen consumption measuring device used to measure the dissolved oxygen consumption of water, and a biochemical oxygen consumption prediction method for predicting biochemical oxygen consumption using the device. [Background technology]

[0002] Biochemical oxygen demand (BOD) is a commonly known water quality index. BOD represents the amount of organic matter in water as the amount of dissolved oxygen consumed by microorganisms in the water. Generally, the higher the BOD value, the worse the water quality is evaluated to be.

[0003] When measuring BOD, a sample is kept in a sealed container at 20°C for five days, and the amount of dissolved oxygen consumed is determined. To measure BOD properly, the difference between the first and second dissolved oxygen concentration measurements should be within the range of 3.5-6.2 mg / L. To meet this requirement, the sample must be diluted before starting the measurement.

[0004] BOD values ​​vary depending on the type of sample, and if the analytical value of the diluted sample (the difference between the first and second dissolved oxygen concentration measurements) falls outside the specified concentration range, it becomes necessary to adjust the dilution and repeat the measurement again. As a result, not only does it take extra time to obtain BOD measurement results, but it also forces the use of samples that have been stored for a long time, which results in the problem of not being able to obtain the true BOD value.

[0005] Patent Document 1 discloses a technique for obtaining BOD measurement results in a short period of time. The method and device for measuring biochemical oxygen consumption disclosed in the document obtain the amount of dissolved oxygen consumed by aerobic microorganisms in a sample over a short period of time (for example, two hours), and predict the BOD value of the sample based on the obtained amount of dissolved oxygen consumed. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-46823 Summary of the Invention [Problem to be solved by the invention]

[0007] According to Patent Document 1, it is possible to determine the appropriate dilution rate of a sample by aerating the sample to saturate the dissolved oxygen concentration, and then measuring the dissolved oxygen concentration in a short period of time (for example, after 60 to 120 minutes), and from the amount of dissolved oxygen consumed, it is possible to determine the appropriate dilution rate of the sample.

[0008] When there are many types of samples to measure the dissolved oxygen consumption, it is necessary to efficiently measure the dissolved oxygen consumption of each sample. However, there is a problem that an apparatus capable of measuring the dissolved oxygen consumption of many samples tends to become large.

[0009] The present invention has been devised in view of the above-mentioned problems, and an object of the present invention is to provide a dissolved oxygen consumption measuring device that can efficiently measure the dissolved oxygen consumption of a large number of samples and can be easily miniaturized. Another object of the present invention is to provide a biochemical oxygen consumption prediction method that can efficiently predict the BOD value in a short time using the dissolved oxygen consumption measuring device of the present invention. [Means for solving the problem]

[0010] A dissolved oxygen consumption measuring device according to a first aspect of the present invention includes a container, a sample liquid supply flow path for supplying sample liquid, an air supply flow path for supplying aeration air, a supply nozzle for supplying fluid selectively supplied from the sample liquid supply flow path and the air supply flow path into the container, and a dissolved oxygen sensor for detecting the dissolved oxygen concentration of the sample liquid supplied to the container.

[0011] With a dissolved oxygen consumption measuring device having such a configuration, the sample liquid and aeration air are selectively supplied into the container from the sample liquid supply channel and the air supply channel, so that the sample liquid and aeration air can be supplied to the container at the same location without moving the container, and the mechanism and structure for moving the supply nozzle can be simplified. As a result, the dissolved oxygen consumption of many samples can be measured efficiently and the device can be made smaller.

[0012] A dissolved oxygen consumption measuring device according to a second aspect of the present invention is the dissolved oxygen consumption measuring device according to the first aspect, further comprising: a sensor arm that holds the dissolved oxygen sensor; a supply arm that is integral with the sensor arm and holds the supply nozzle; and arm driving means that can operate the sensor arm and the supply arm between a sensor insertion position where the dissolved oxygen sensor is inserted into one of the containers located at a specific position, and a nozzle insertion position where the supply nozzle is inserted into one of the containers located at the specific position.

[0013] A dissolved oxygen consumption measuring device according to a third aspect of the present invention is the dissolved oxygen consumption measuring device according to the second aspect, wherein a tapered opening that narrows in diameter toward the bottom is formed on the top surface of the container. A tapered stopper that narrows in diameter toward the bottom is provided on the body of the dissolved oxygen sensor. When the sensor arm is arranged at the sensor insertion position, the stopper fits snugly into the opening of the container, sealing the container.

[0014] A fourth aspect of the present invention relates to the dissolved oxygen consumption measuring device of the third aspect, and further includes a turntable that holds the plurality of containers in a ring shape at predetermined intervals, a turntable drive means for driving the turntable to rotate, and a control device. The control device includes a first positioning means that positions one of the plurality of containers at the specific position via the turntable drive means and then positions the supply arm at a nozzle insertion position via the arm drive means, a sample liquid / air supplying means that supplies sample liquid into the container at the specific position and aeration air into the container at the specific position, a second positioning means that positions the sensor arm at a sensor insertion position via the arm drive means, a detection means that detects the dissolved oxygen concentration based on output information from the dissolved oxygen sensor, and a measurement means that measures the dissolved oxygen consumption from the dissolved oxygen concentration detected by the detection means.

[0015] A dissolved oxygen consumption measuring device according to a fifth aspect of the present invention is the dissolved oxygen consumption measuring device according to the first aspect, further comprising a cleaning water supply flow path for supplying cleaning water, wherein the supply nozzle supplies fluid selectively supplied from the sample liquid supply flow path, the air supply flow path, and the cleaning water supply flow path into the container.

[0016] A biochemical oxygen consumption prediction method according to a sixth aspect of the present invention includes the steps of aerating a sample liquid using a dissolved oxygen consumption measuring device according to any one of the first to fifth aspects, measuring a change in the amount of dissolved oxygen in the aerated sample liquid within a predetermined period of time, and predicting the biochemical oxygen consumption of the sample liquid based on the change in the amount of dissolved oxygen. [Effects of the Invention]

[0017] The dissolved oxygen consumption measuring device according to the present invention can efficiently measure dissolved oxygen consumption and facilitates miniaturization of the device. Furthermore, the biochemical oxygen consumption prediction method according to the present invention can efficiently predict BOD. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a perspective view of a dissolved oxygen consumption measuring device according to an embodiment of the present invention. [Figure 2] 1 is a front view of a dissolved oxygen consumption measuring device according to an embodiment of the present invention. [Figure 3] 1 is a plan view of a dissolved oxygen consumption measuring device according to an embodiment of the present invention. [Figure 4] 4 is a diagram in which the control box 13 is omitted from FIG. 3. [Figure 5] FIG. 2 is a perspective view showing a state in which the opening of the lid of the container is closed by a plug member. [Figure 6] FIG. 2 is a perspective view showing a state in which the opening of the lid of the container is open. [Figure 7] 10 is a perspective view showing a state immediately before the plug mounting member is pushed by the plug pushing portion of the sensor arm. FIG. [Figure 8] 10 is a perspective view showing a state in which the plug mounting member is pushed by the plug pushing portion of the sensor arm and the opening of the lid portion of the container is opened. FIG. [Figure 9] 1 is a perspective view of a dissolved oxygen consumption measuring device according to an embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view showing the arm driving means, illustrating a state in which the supply nozzle is at a processing position. [Figure 11] FIG. 10 is a perspective view showing the arm driving means, illustrating a state in which the sensor nozzle is at a processing position. [Figure 12] FIG. 2 is a diagram illustrating an example of a drum. [Figure 13] 4 is a flowchart illustrating an example of a processing operation executed by a control device. [Figure 14] 14 is a flowchart showing detailed steps of the sample liquid supplying process of FIG. 13. [Figure 15] 14 is a flowchart showing detailed steps of the DO detection process of FIG. 13. [Figure 16] 14 is a flowchart showing detailed steps of the cleaning process of FIG. 13. DETAILED DESCRIPTION OF THE INVENTION

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dissolved oxygen consumption measuring device according to an embodiment of the present invention will be described below with reference to the drawings.

[0020] As shown in Figures 1 to 4, the dissolved oxygen consumption measuring device 1 includes a number of containers 2, a turntable device 3, a dissolved oxygen (DO) sensor 4, a sensor arm 5, a sample liquid supply flow path 7, an air supply flow path 8, a cleaning water supply flow path 9, a supply nozzle 10, a supply arm 11, an arm driving means 12, a control device, a base plate 14, etc.

[0021] The containers 2 store sample liquid (specimen) and the like supplied from the sample liquid supply flow path 7. In this embodiment, 12 containers 2 are arranged at equal intervals in a ring shape and held on a turntable 15 of the turntable device 3. The 12 containers 2 include 10 sample liquid containers for storing sample liquid, one cleaning water container 2 for storing cleaning water, and one DO sensor storage container 2 for storing a DO sensor 4. Note that the number of containers 2 and the allocation of the uses of the containers 2 are not limited to those described above and can be changed as appropriate.

[0022] As shown in Figures 5 and 6, the container 2 in this embodiment has a substantially hemispherical bottom and a cylindrical body. The container 2 also has a lid 17 that closes an opening formed at the upper edge of the body. An opening 17a is formed in a portion of the lid 17, and the opening 17a is closed by a plug member 18 in an openable and closable manner. The inner circumferential surface of the opening 17a is tapered downward, and the plug member 18 is also tapered downward. Therefore, the interior of the container 2, with the opening 17a closed by the plug member 18, is kept airtight and liquidtight. A drain port is formed in the bottom of the container 2 for discharging the liquid inside.

[0023] The plug member 18 is attached to a plug mounting member 21, which is rotatably attached to the lid 17 of the container 2 via a hinge 21a. The hinge 21a is provided midway along the length of the plug mounting member 21, and the plug member 18 is attached to one end of the plug mounting member 21. When the other end of the plug mounting member 21 is pressed downward, the one end of the plug mounting member 21 rotates upward, and as the plug member 18 rotates, it moves away from the opening 17a. On the other hand, when the downward pressing force on the other longitudinal end of the plug mounting member 21 is released, the force of a spring (not shown) rotates the other end of the plug mounting member 21 upward, and at the same time, the one end of the plug mounting member 21 rotates downward, and as the one end rotates, the plug member 18 closes the opening 17a. 7 and 8, the other end of the plug mounting member 21 is pushed by the plug pushing portion 5b of the sensor arm 5 or the plug pushing portion 11b of the supply arm 11, which will be described later. The plug pushing portion 5b shown in FIGS. 7 and 8 is the plug pushing portion 5b of the sensor arm 5, but the plug pushing portion 11b of the supply arm 11 also has a shape similar to that of the plug pushing portion 5b of the sensor arm 5.

[0024] As shown in Figures 1 and 2, a drain pipe 19 that guides wastewater to a desired location is connected to a drain outlet formed in the bottom of the container 2. A flexible tube made of a transparent material, for example, can be used as the drain pipe 19. An on-off valve 20 that opens and closes the flow path in the drain pipe 19 is installed midway through the drain pipe 19. In this embodiment, an electromagnetic valve that opens and closes the flow path in the drain pipe 19 in accordance with commands from a control device is used as the on-off valve 20. In Figures 1 and 2, only one drain pipe 19 is shown, and the other drain pipes 19 are not shown, but the drain pipes 19 are connected to the drain outlets of all of the containers 2.

[0025] The turntable device 3 includes a turntable 15, a valve support plate 16, a turntable driving means (not shown), and the like.

[0026] As shown in FIGS. 1 and 4, the turntable 15 is formed in a disk shape and has holding holes (not shown) into which twelve containers 2 are individually fitted and held. In this embodiment, the number of holding holes is twelve, but the number of holding holes may be changed as appropriate. The turntable 15 is provided with drainage holes (not shown) for draining liquid that overflows from the containers 2. A drain pipe 23 is connected to the drainage hole. The drainage pipe 23 is arranged to guide the drainage to a drainage receiver 22 placed in a predetermined position on the base plate 14. A drain pipe 22a is connected to the drainage receiver 22, which further guides the drainage to another location. Note that in FIGS. 1 and 2, only one drainage pipe 23 is shown, and the other drainage pipes 23 are not shown. However, the turntable 15 is actually provided with a large number of drainage holes spaced equally apart in the rotational direction, and all of the drainage holes are connected to the drainage pipes 23.

[0027] An on-off valve 20 that opens and closes the flow path in the drain pipe 19 is attached to the valve support plate 16. The valve support plate 16 is connected to the turntable 15 at the top and bottom via a plurality of supports 24. Therefore, the valve support plate 16 rotates integrally with the turntable 15. The plurality of supports 24 are erected at equal intervals on an imaginary circle whose center is the rotation center of the turntable 15.

[0028] The turntable driving means is composed of an electric motor or the like, and rotates the turntable 15 and the valve support plate 16 in accordance with commands from the control device.

[0029] The DO sensor 4 is a dissolved oxygen sensor for detecting the dissolved oxygen concentration of a sample liquid and includes a body 4a and a DO electrode 4b disposed at the lower end of the body 4a. A tapered stopper 4c, which tapers downward, is fixed to the outer periphery of the body 4a. As shown in FIG. 11, the DO sensor 4 illustrated in this embodiment has a body 4a that is composed of a small body 4a1 with a relatively small diameter and a large body 4a2 that is formed above the small body 4a1 and has a larger diameter than the small body 4a1, and the stopper 4c is fixed to the small body 4a1.

[0030] When the DO sensor 4 detects the dissolved oxygen concentration of the sample liquid, the DO sensor 4 is inserted downward into the opening 17a formed in the lid 17 of the container 2 when the container 2 is filled to the brim with the sample liquid, and when some of the sample liquid overflows from the container 2, the plug 4c of the DO sensor 4 fits snugly into the opening 17a of the lid 17 of the container 2, closing the opening 17a and sealing the container 2. Both the plug 4c of the DO sensor 4 and the opening 17a of the lid 17 of the container 2 are tapered downward, so that the container 2 is sealed in an airtight state.

[0031] The sensor arm 5 holds the DO sensor 4. The sensor arm 5 is provided integrally with the supply arm 11 and rotates and moves up and down integrally therewith. As shown in FIGS. 10 and 11, the sensor arm 5 has an arm main body 5a extending horizontally and a plug pushing portion 5b extending downward from the tip of the arm main body 5a. A sensor holding portion 5c that holds the DO sensor 4 is formed on the arm main body 5a.

[0032] The sample liquid supply flow path 7 is formed from a tubing material. For example, a flexible tube made of a transparent material can be used as the tubing material. The upstream end of the sample liquid supply flow path 7 is connected to a bottle 26 containing, for example, 100 ml of sample liquid, and the downstream end of the sample liquid supply flow path 7 is connected to a supply nozzle 10. An electric pump P1 is disposed midway along the sample liquid supply flow path 7, and when the electric pump P1 is driven, the sample liquid in the bottle 26 is pressure-fed to the supply nozzle 10 side and discharged from the supply nozzle 10.

[0033] The air supply flow path 8 is also formed of a tubular material. For example, a flexible tube made of a transparent material can be used as the tubular material. The upstream end of the air supply flow path 8 is connected to an electric air pump P2, and the downstream end of the air supply flow path 8 is connected to a supply nozzle 10. When the electric air pump P2 is driven, aeration air is discharged from the supply nozzle 10.

[0034] The cleaning water supply flow path 9 is also formed from a pipe material. For example, a flexible tube made of a transparent material can be used as the pipe material. The upstream end of the cleaning water supply flow path 9 is connected to the bottom of a cleaning water container 27 containing cleaning water, and the downstream end of the cleaning water supply flow path 9 is connected to a supply nozzle 10. An on-off valve 28 that opens and closes the cleaning water supply flow path 9 is installed midway along the cleaning water supply flow path 9. The cleaning water container 27 is positioned higher than the supply nozzle 10, and when the on-off valve 28 opens the cleaning water supply flow path 9, gravity causes the cleaning water in the cleaning water container 27 to flow toward the supply nozzle 10 and is supplied from the supply nozzle 10 into the container 2. On the other hand, when the on-off valve 28 closes the cleaning water supply flow path 9, the supply of cleaning water from the supply nozzle 10 into the container 2 stops. In this embodiment, an electromagnetic on-off valve 28 is used as the on-off valve that opens and closes the cleaning water supply flow path 9 in accordance with commands from a control device.

[0035] Supply nozzle 10 supplies a fluid selectively supplied from sample liquid supply channel 7, air supply channel 8, and cleaning water supply channel 9 into container 2 by a "selective supply means" that selectively supplies fluid from sample liquid supply channel 7, air supply channel 8, and cleaning water supply channel 9. That is, one of the fluids, sample liquid, cleaning water, and aeration air, is supplied to supply nozzle 10, and the fluid is supplied into container 2 through supply nozzle 10. In this embodiment, a rotary stirring blade 30 that stirs the liquid in container 2 is installed near supply nozzle 10. Rotary stirring blade 30 is attached to the lower end of a rotary shaft 31a that is rotated by an electric motor 31 mounted on supply arm 11. Electric motor 31 is driven to rotate in accordance with commands from a control device.

[0036] In this embodiment, the "selective supply means" is composed of a control device, an electric pump P1, an electric air pump P2, an on-off valve 28, etc. For example, when sample liquid is supplied to the supply nozzle 10, the control device drives the electric pump P1 provided in the sample liquid supply flow path 7, stops the electric air pump P2 that supplies air to the air supply flow path 8, and closes the on-off valve 28 provided in the cleaning water supply flow path 9. When aeration air is supplied to the supply nozzle 10, the control device stops the electric pump P1 provided in the sample liquid supply flow path 7, drives the electric air pump P2 that supplies air to the air supply flow path 8, and closes the on-off valve 28 provided in the cleaning water supply flow path 9. When cleaning water is supplied to the supply nozzle 10, the control device stops the electric pump P1 provided in the sample liquid supply flow path 7, stops the electric air pump P2 that supplies air to the air supply flow path 8, and opens the on-off valve 28 provided in the cleaning water supply flow path 9.

[0037] The configuration of the "selective supply means" is not limited to the above, and can be configured using various piping components, devices, valves, etc. For example, a directional control valve can be interposed between the downstream ends of the sample liquid supply flow path 7, the air supply flow path 8, and the cleaning water supply flow path 9 and the supply nozzle 10, and the directional control valve can be used as the selective supply means to selectively connect one of the sample liquid supply flow path 7, the air supply flow path 8, and the cleaning water supply flow path 9 to the supply nozzle 10.

[0038] In this embodiment, supply nozzle 10 is configured using one nozzle tube, and sample liquid supply flow path 7, air supply flow path 8, and cleaning water supply flow path 9 are connected to this one nozzle tube, but three nozzle tubes may be used as supply nozzle 10. When three nozzle tubes are used, it is desirable to connect a nozzle tube to the downstream end of sample liquid supply flow path 7, air supply flow path 8, and cleaning water supply flow path 9, respectively, and to arrange the three nozzle tubes adjacent to each other in parallel so that the three nozzle tubes can be inserted simultaneously into opening 17a of lid 17 of container 2.

[0039] Supply arm 11 holds supply nozzle 10. Supply arm 11 is provided integrally with sensor arm 5 and rotates and moves up and down integrally therewith. As shown in FIGS. 10 and 11, supply arm 11 has arm main body 11a extending horizontally and plug pushing portion 11b extending downward from the tip of arm main body 11a. Nozzle holding portion 11c that holds supply nozzle 10 is formed on arm main body 11a. Supply arm 11 and sensor arm 5 extend at right angles to each other when viewed from above, and their base ends are joined so as to rotate integrally.

[0040] The arm driving means 12 is provided to raise and lower and rotate the sensor arm 5 and the supply arm 11. The arm driving means 12 can move the sensor arm 5 and the supply arm 11 between a "sensor insertion position" (see FIGS. 9 and 11) where the DO sensor 4 is inserted into one container 2 placed at a specific rotation position (hereinafter referred to as the "processing position") by the turntable 15, and a "nozzle insertion position" (see FIG. 10) where the supply nozzle 10 is inserted into one container 2 placed at the processing position.

[0041] In order to achieve the above operation, the arm driving means 12 includes an electric jack device 35, a lifting arm 36 that is raised and lowered by the electric jack device 35, a drum 38 having a guide groove 37 formed on its cylindrical outer surface, a guided element 39a fitted into the guide groove 37, and a guided element support part 39 to the tip of which the guided element 39a is attached and whose base end is fixed to a stationary member.

[0042] The electric jack device 35 includes an electric motor 42, a jack bolt 35a whose axis is rotated by the electric motor 42, two guide shafts 35b arranged parallel to the jack bolt 35a, and a lifting member 35c that is guided by the guide shafts 35b and moves up and down as the jack bolt 35a rotates forward and backward. The electric motor 42 is driven in accordance with commands from a control device, and together with the lifting member 35c, lifts and lowers a lifting arm 36 fixed to the lifting member 35c.

[0043] The lifting arm 36 rotatably supports a rotary shaft (not shown), and the base ends of the sensor arm 5 and the supply arm 11 are attached to the upper end of the rotary shaft so as to rotate together. A drum 38 is fixed to the lower end of the rotary shaft so as to be coaxial with the rotary shaft. This allows the sensor arm 5 and the supply arm 11 to rotate together with the drum 38 in forward and reverse directions.

[0044] The guided element support portion 39 has a base end fixed to a bracket 41, which is a stationary member, and a tip end extending horizontally. The guided element 39a attached to the tip end of the guided element support portion 39 is slidably fitted into a guide groove 37 formed in the drum 38. As shown in Fig. 12, the guide groove 37 is made up of a first guide groove portion 371 to a ninth guide groove portion 379, which are connected to each other via bent portions.

[0045] The first guide groove 371 extends downward from the upper end of the drum 38 along the generatrix of the outer circumferential surface of the drum 38. When the guided element 39a is fitted into the first guide groove 371, the tip of the supply nozzle 10 is positioned at the same position as the opening 17a of the container 2 in the "processing position" when viewed from above. When the sensor arm 5 and the supply arm 11 rise, the guided element 39a moves downward along the first guide groove 371. Conversely, when the sensor arm 5 and the supply arm 11 lower, the guided element 39a moves upward along the first guide groove 371. A lower limit position is set for the lowering movement of the sensor arm 5 and the supply arm 11 (the control device stops the lowering movement of the lifting arm 36 when a sensor for detecting the lower limit position detects the lower limit position). When the sensor arm 5 and the supply arm 11 reach the lower limit position, the tip of the supply nozzle 10 is positioned at a predetermined position inside the container 2.

[0046] Second guide groove 372 is formed in a direction inclined with respect to the generatrix of the outer circumferential surface of drum 38, and its upper end is connected to the lower end of first guide groove 371 via a bent portion. When guided element 39a is fitted into second guide groove 372, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When sensor arm 5 and supply arm 11 are raised while guided element 39a is fitted into second guide groove 372, the tip of supply nozzle 10 rotates away from opening 17a of container 2, which is in the "processing position," as viewed from above, and the tip of DO sensor 4 rotates toward opening 17a.

[0047] Third guide groove 373 is formed along the generatrix of the outer peripheral surface of drum 38, and its upper end is connected to the lower end of second guide groove 372 via a bent portion. When guided element 39a is fitted into third guide groove 373, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When guided element 39a is fitted into third guide groove 373, sensor arm 5 and supply arm 11 move up and down without rotating.

[0048] Fourth guide groove 374 is formed in a direction inclined with respect to the generatrix of the outer circumferential surface of drum 38, and its upper end is connected to the lower end of third guide groove 373 via a bent portion. When guided element 39a is fitted in fourth guide groove 374, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When sensor arm 5 and supply arm 11 are raised while guided element 39a is fitted in fourth guide groove 374, the tip of supply nozzle 10 rotates away from opening 17a of container 2, which is in the "processing position," as viewed from above, and the tip of DO sensor 4 rotates toward opening 17a.

[0049] Fifth guide groove 375 is formed along the generatrix of the outer peripheral surface of drum 38, and its middle portion is connected to the lower end of fourth guide groove 374. When guided element 39a is fitted into fifth guide groove 375, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When guided element 39a is fitted into fifth guide groove 375, sensor arm 5 and supply arm 11 move up and down without rotating.

[0050] The sixth guide groove 376 is formed along the generatrix of the outer peripheral surface of the drum 38, and its lower end is connected to the upper end of the fifth guide groove 375 via a bent portion. The lower end of the sixth guide groove 376 is also connected to the upper end of a ninth guide groove 379, described later, via a bent portion. When the guided element 39a is fitted into the sixth guide groove 376, the tips of the supply nozzle 10 and the DO sensor 4 are positioned higher than the container 2. When the guided element 39a is fitted into the sixth guide groove 376, the sensor arm 5 and the supply arm 11 move up and down without rotating.

[0051] Seventh guide groove 377 is formed in a direction inclined with respect to the generatrix of the outer peripheral surface of drum 38, and its lower end is connected to the upper end of sixth guide groove 376 via a bent portion. When guided element 39a is fitted into seventh guide groove 377, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When sensor arm 5 and supply arm 11 are lowered with guided element 39a fitted into seventh guide groove 377, the tip of supply nozzle 10 rotates away from opening 17a of container 2, which is in the "processing position," as viewed from above, and the tip of DO sensor 4 rotates toward opening 17a. Conversely, when the guided element 39a is inserted into the seventh guide groove portion 377, and the sensor arm 5 and supply arm 11 move up and down, the tip of the supply nozzle 10 rotates in a direction approaching the opening 17a of the container 2 in the "processing position" when viewed from above, and the tip of the DO sensor 4 rotates in a direction away from the opening 17a.

[0052] The eighth guide groove 378 extends downward from the upper end of the drum 38 along the generatrix of the outer circumferential surface of the drum 38. The lower end of the eighth guide groove 378 is connected to the upper end of the seventh guide groove 377 via a bent portion. When the guided element 39a is fitted into the eighth guide groove 378, the tip of the DO sensor 4 is positioned at the same position as the opening 17a of the container 2 in the "processing position" when viewed from above. When the sensor arm 5 and the supply arm 11 rise, the guided element 39a moves downward along the eighth guide groove 378. Conversely, when the sensor arm 5 and the supply arm 11 descend, the guided element 39a moves upward along the eighth guide groove 378. A lower limit position is set for the downward movement of the sensor arm 5 and the supply arm 11 (the control device stops the downward movement of the lifting arm 36 when the lower limit position detection sensor detects the lower limit position), and when the sensor arm 5 and the supply arm 11 reach the lower limit position, the tip of the DO sensor 4 is inserted inside the container 2.

[0053] Ninth guide groove 379 is formed in a direction inclined with respect to the generatrix of the outer peripheral surface of drum 38, with its upper end connected to the lower end of sixth guide groove 376 via a bent portion and its lower end connected to the middle of third guide groove 373. When guided element 39a is fitted into ninth guide groove 379, the tips of supply nozzle 10 and DO sensor 4 are positioned higher than container 2. When sensor arm 5 and supply arm 11 are lowered with guided element 39a fitted into ninth guide groove 379, the tip of supply nozzle 10 rotates away from opening 17a of container 2, which is in the "processing position," as viewed from above, and the tip of DO sensor 4 rotates toward opening 17a. Conversely, when the guided element 39a is inserted into the ninth guide groove portion 379 and the sensor arm 5 and supply arm 11 move up and down, the tip of the supply nozzle 10 rotates in a direction approaching the opening 17a of the container 2 in the "processing position" when viewed from above, and the tip of the DO sensor 4 rotates in a direction away from the opening 17a.

[0054] The first guide groove portion 371, the third guide groove portion 373, the fifth guide groove portion 375, the sixth guide groove portion 376 and the eighth guide groove portion 378 are all formed along the generatrix of the outer peripheral surface of the drum 38, but the circumferential positional relationship of these guide groove portions is, when viewed from above, in the clockwise order of the first guide groove portion 371, the third guide groove portion 373, the sixth guide groove portion 376, the fifth guide groove portion 375 and the eighth guide groove portion 378.

[0055] The control device is configured to include, for example, a computer with an operating system (OS) and a predetermined application program installed, and a control box 13. The computer is equipped with user interfaces such as a keyboard and a mouse, and an output device such as a monitor. The control device controls the operation of the electric pump P1, the electric air pump P2, the on-off valve 28, the electric motors 31 and 42, etc., based on various input information (including sensor information that detects the position of each operating component) and predetermined procedures.

[0056] Next, an example of the processing operation executed by the control device will be described with reference to the flowcharts shown in FIGS.

[0057] First, in a preparation stage, the user prepares one or more bottles 26 containing sample liquid for measuring the dissolved oxygen consumption amount, and inserts the upstream end of the sample liquid supply channel 7 into one of the bottles 26.

[0058] Next, the user starts the control device, and an operation for setting conditions is performed on the started control device (ST1). Examples of the conditions to be set include the saturated concentration of dissolved oxygen, the number of containers 2 to be used, position information (1, 2, 3, ...) of the containers 2 to be used on the turntable 15, and information on the sample liquid to be supplied to each container 2. In this embodiment, the number of containers 2 to be used is set to 10. Furthermore, it is assumed that the sample liquid is supplied to the containers 2 held in consecutive positions 1 to 10 of the 12 positions for holding the containers 2 on the turntable 15. In the initial state upon starting up the control device, as shown in FIG. 11, the guided element 39a is fitted near the upper end of the eighth guide groove portion 378 of the drum 38, and the tip of the DO sensor 4 is inserted into a DO sensor storage container (not shown in FIG. 11) arranged at the "processing position."

[0059] Next, the user switches the control device between "automatic mode" and "manual mode" (ST2). If "manual mode" is selected (ST3: NO), it becomes possible to manually operate various actuators (e.g., electric pump P1, electric air pump P2, electric motors 31 and 42, turntable driving means, etc.) and valves (e.g., on-off valve 28, etc.) provided in the dissolved oxygen consumption measuring device 1.

[0060] On the other hand, if "automatic mode" is selected (ST3: YES), a process for supplying sample liquid from the bottle 26 to the container 2 (hereinafter also referred to as "sample liquid supply process") is executed (ST4).

[0061] In the "sample liquid supply process," the control device drives the electric motor 31 of the electric jack device 35 to raise the lifting arm 36. As the lifting arm 36 rises, the sensor arm 5, supply arm 11, and drum 38 also rise (ST11). The guided element 39a passes through the eighth guide groove 378, the seventh guide groove 377, the sixth guide groove 376, the ninth guide groove 379, and the third guide groove 373, and then reaches a position between the third guide groove 373 and the fourth guide groove 374 (hereinafter also referred to as the "origin position S"). When the guided element 39a reaches the origin position S, a predetermined position detection sensor sends information informing the control device of the arrival of the guided element 39a. Upon receiving the information, the control device immediately stops the raising of the lifting arm 36, the sensor arm 5, the supply arm 11, and the like. When the guided member 39a is at the origin position S of the guide groove 37, the sensor arm 5 and the supply arm 11 are positioned as shown in Figures 1 and 2, the tips of the DO sensor 4 and the supply nozzle 10 are positioned higher than the lid 17 of the container 2, and the plug pushing portions 5b, 11b of the DO sensor 4 and the supply nozzle 10 are also positioned higher than the plug mounting member 21.

[0062] Next, the control device rotates the turntable 15 via the turntable driving means (not shown) so that the container 2 placed at the position on the turntable 15 whose position information is the Nth position (initial value is N=1) to be processed comes to the "processing position" (ST12).

[0063] Next, the control device drives the electric motor 31 of the electric jack device 35 to lower the lifting arm 36. As the lifting arm 36 lowers, the sensor arm 5, the supply arm 11, and the drum 38 also lower (ST13). At this time, the guided element 39a passes from the "origin position S" through the third guide groove portion 373 and the second guide groove portion 372 and then through the first guide groove portion 371. When the guided element 39a reaches a predetermined position near the upper end of the first guide groove portion 371 (hereinafter referred to as the "supply nozzle insertion corresponding position 371a"), a predetermined position detection sensor sends information notifying the control device of the arrival of the guided element 39a. Upon receiving the information, the control device immediately stops the electric motor 31 of the electric jack device 35 to stop the lowering of the lifting arm 36. When the guided member 39a is in the "supply nozzle insertion corresponding position 371a" of the guide groove 37, the supply arm 11 takes the position shown in Figure 10, and as shown in Figures 7 and 8, the plug pushing portion 11b of the supply arm 11 pushes the plug mounting member 21 downward just before reaching that position, thereby inserting the tip of the supply nozzle 10 into the opening 17a of the lid portion 17 which has been opened.

[0064] Next, the control device executes a process for supplying the sample liquid contained in the bottle 26 to the container 2 (ST14). Specifically, the control device drives the electric pump P1 provided in the sample liquid supply flow path 7 to supply the sample liquid contained in the bottle 26 to the supply nozzle 10, and the sample liquid is supplied into the container 2 through the supply nozzle 10. At this time, the electric air pump P2 that supplies air to the air supply flow path 8 is stopped, and the on-off valve 28 provided in the cleaning water supply flow path 9 is closed.

[0065] Next, the control device executes a process for supplying aeration air to the sample liquid in the container 2 (ST15). Specifically, the control device drives the electric air pump P2, which supplies air to the air supply flow path 8, to supply aeration air to the supply nozzle 10, and the aeration air is supplied to the sample liquid in the container 2 through the supply nozzle 10. At this time, the electric pump P1 provided in the sample liquid supply flow path 7 is stopped, and the on-off valve 28 provided in the cleaning water supply flow path 9 is closed. The aeration air is supplied for a period of time (e.g., 8 minutes) sufficient for the dissolved oxygen concentration of the sample liquid in the container 2 to become saturated. In addition to the process for supplying aeration air, the control device also adds 1 to the processing target position information N on the turntable 15.

[0066] Next, the control device determines whether or not it is necessary to supply sample liquid to other containers 2. Specifically, if the control device determines that the processing target position information N has not reached the "number of containers 2 to be used (10 in this embodiment)", it determines that it is necessary to supply sample liquid to other containers 2, and if the processing target position information N has reached the "number of containers 2 to be used (10 in this embodiment)", it determines that it is not necessary to supply sample liquid to other containers 2.

[0067] If the control device determines that sample liquid needs to be supplied to other containers 2, it repeats the processing operations of ST11 to ST15. However, when the sample liquid supply process is performed continuously, the path taken by guided element 39a in ST11 is slightly different from that described above. That is, when sensor arm 5, supply arm 11, and drum 38 are raised in ST11, guided element 39a passes from first guide groove 371, through second guide groove 372, and through third guide groove 373, to reach "origin position S." Note that if different sample liquids are to be supplied to each container 2, the upstream end of sample liquid supply flow path 7 must be replaced with a bottle 26 containing a different sample liquid.

[0068] On the other hand, if the control device determines that there is no need to supply sample liquid to any other containers 2, it then starts a process for detecting the dissolved oxygen concentration of the sample liquid supplied to each container 2 (hereinafter also referred to as "DO detection process") (ST5), and resets the processing target position information N on the turntable 15 to 1. In this embodiment, the "number of containers 2 to be used" is 10, and it takes about 10 minutes to perform the processing operations from ST11 to ST15 on one container 2, and it takes about 100 minutes to supply sample liquid to and aerate the 10 containers 2.

[0069] In the "DO detection process," the control device drives the electric motor 31 of the electric jack device 35 to raise the lifting arm 36. As the lifting arm 36 rises, the sensor arm 5, the supply arm 11, and the drum 38 also rise (ST21), and the guided element 39a starts from the first guide groove portion 371 and passes through the second guide groove portion 372, the third guide groove portion 373, and the fourth guide groove portion 374. When the guided element 39a reaches a predetermined position in the fifth guide groove portion 375 (hereinafter also referred to as the "arm switching position T"), a predetermined position detection sensor sends information notifying the arrival of the guided element 39a to the control device. Upon receiving the information, the control device immediately stops the raising operation of the lifting arm 36 of the electric jack device 35. Furthermore, when the guided member 39a is at the arm switching position T of the guide groove 37, the tips of the DO sensor 4 and the supply nozzle 10 are positioned higher than the lid portion 17 of the container 2, and the plug pushing portions 5b, 11b of the DO sensor 4 and the supply nozzle 10 are also positioned higher than the plug mounting member 21.

[0070] Next, the control device rotates the turntable 15 via the turntable driving means (not shown) so that the container 2 placed at the position on the turntable 15 whose position information indicates the Nth container to be processed comes to the "processing position" (ST22).

[0071] Next, the control device drives the electric motor 31 of the electric jack device 35 to lower the lifting arm 36. As the lifting arm 36 lowers, the sensor arm 5, the supply arm 11, and the drum 38 also lower (ST23). At this time, the guided element 39a passes from the "arm switching position T" through the fifth guide groove portion 375, the sixth guide groove portion 376, the seventh guide groove portion 377, and the eighth guide groove portion 378. When the guided element 39a reaches a predetermined position in the eighth guide groove portion 378 (hereinafter referred to as the "sensor insertion position 378a"), a predetermined position detection sensor sends information notifying the arrival of the guided element 39a to the control device. Upon receiving the information, the control device immediately stops the lowering operation of the lifting arm 36. When the guided element 39a is in the "sensor insertion corresponding position 378a" of the guide groove 37, the sensor arm 5 is in the state shown in Figures 4, 9 and 11, and the plug pushing portion 5b of the sensor arm 5 pushes the plug mounting member 21 downward, thereby inserting the tip portion of the DO sensor 4 (DO electrode 4b) into the opening 17a of the opened lid portion 17.

[0072] Next, the control device detects the dissolved oxygen concentration of the sample liquid in the container 2 at the processing position based on the information received from the DO sensor 4, and measures the dissolved oxygen consumption by subtracting the detected dissolved oxygen concentration from a previously registered saturated dissolved oxygen concentration (ST24). This measurement of the dissolved oxygen consumption is performed a previously set time (approximately 100 minutes in this embodiment) after the sample liquid in the container 2 has been aerated. The measured dissolved oxygen consumption is stored in the control device and can be displayed on the control device's monitor or the like by a predetermined user operation. At this time, the dissolved oxygen consumption of each container 2 may be displayed in association with position information on the turntable 15 or information about the sample liquid previously registered by the user.

[0073] Then, when the control device completes measurement of the dissolved oxygen concentration of the sample liquid in the container 2 at the processing position, it drives the electric motor 31 of the electric jack device 35 to raise the lifting arm 36. As the lifting arm 36 rises, the sensor arm 5, the supply arm 11, and the drum 38 also rise (ST25), and the guided element 39a starts from the "sensor insertion corresponding position 378a" of the eighth guide groove 378 and passes through the seventh guide groove 377, the sixth guide groove 376, the ninth guide groove 379, and the third guide groove 373. When the guided element 39a reaches the "origin position S" of the fourth guide groove 374, a predetermined position detection sensor sends information notifying the arrival to the control device, and the control device immediately stops the raising operation of the lifting arm 36 of the electric jack device 35.

[0074] Next, the control device performs a process to drain the sample liquid in the container 2 placed at the processing position from the container 2 (ST26). Specifically, the control device switches the on-off valve 20, which opens and closes the flow path of the drain pipe 19 connected to the bottom of the container 2 placed at the processing position, from a closed state to an open state, thereby draining the sample liquid from the container 2.

[0075] Next, the control device determines whether it is necessary to measure the dissolved oxygen concentration of the sample liquid in the other containers 2. Specifically, if the control device determines that the processing target position information N has not reached the "number of containers 2 to be used (10 in this embodiment)", it determines that it is necessary to measure the dissolved oxygen concentration of the sample liquid in the other containers 2, and if the processing target position information N has reached the "number of containers 2 to be used (10 in this embodiment)", it determines that it is not necessary to measure the dissolved oxygen concentration of the sample liquid in the other containers 2.

[0076] If the control device determines that the dissolved oxygen concentration of the sample liquid in another container 2 also needs to be measured, the processing operations of ST21 to ST26 are repeatedly executed for the other container 2. However, when the DO detection process is executed continuously, the path taken by the guided element 39a in ST21 is slightly different from that described above. That is, when the sensor arm 5, supply arm 11, and drum 38 are raised in ST21, the guided element 39a enters the fifth guide groove portion 375 from the "origin position S" and reaches the "arm switching position T."

[0077] On the other hand, if the control device determines that there is no need to measure the dissolved oxygen concentration of the sample liquid contained in other containers 2, the control device starts a process to clean the DO sensor 4 (hereinafter also referred to as the "DO sensor cleaning process") (ST6).

[0078] In the "DO sensor cleaning process," if the guided element 39a is not positioned at the "origin position S," the control device raises the sensor arm 5 and the supply arm 11 (ST31) to position the guided element 39a at the "origin position S."

[0079] Next, the control device rotates the turntable 15 via the turntable driving means (not shown) so that the container 2 (cleaning container) located at the 11th position on the turntable 15, which has been preset, comes to the "processing position" (ST32).

[0080] Next, the control device drives the electric motor 31 of the electric jack device 35 to lower the lifting arm 36. As the lifting arm 36 lowers, the sensor arm 5, the supply arm 11, and the drum 38 also lower (ST33). At this time, the guided element 39a passes from the "origin position S" of the fourth guide groove 374 through the third guide groove 373 and the seventh guide groove 377. When the guided element 39a reaches the "supply nozzle insertion position 371a" of the seventh guide groove 377, the control device immediately stops the lowering of the lifting arm 36. At this time, the plug pushing portion 5b of the sensor arm 5 pushes the plug mounting member 21 downward, thereby inserting the tip of the supply nozzle 10 into the opening 17a of the lid 17 of the cleaning container, which has been opened.

[0081] Next, the control device executes processing to supply the cleansing water contained in the cleansing water container 27 to the cleansing water container 2 (ST34). Specifically, the control device opens the on-off valve 28 provided in the cleansing water supply flow path 9, thereby supplying the cleansing water contained in the cleansing water container 27 to the supply nozzle 10, and the cleansing water is supplied into the container 2 through the supply nozzle 10. At this time, the electric pump P1 and the electric air pump P2 are stopped.

[0082] Next, the control device drives the electric motor 31 of the electric jack device 35 to raise the lifting arm 36. As the lifting arm 36 rises, the sensor arm 5, the supply arm 11, and the drum 38 also rise (ST35). At this time, the guided element 39a passes from the first guide groove portion 371, through the second guide groove portion 372, the third guide groove portion 373, and the fourth guide groove portion 374, and reaches the "arm switching position T" of the fifth guide groove portion 375. When the guided element 39a reaches the "arm switching position T," the control device stops the lifting of the lifting arm 36.

[0083] Next, the control device drives the electric motor 31 of the electric jack device 35 to lower the lifting arm 36. As the lifting arm 36 lowers, the sensor arm 5, supply arm 11, and drum 38 also lower. At this time, the guided element 39a passes from the "arm switching position T" of the fifth guide groove portion 375, passes through the sixth guide groove portion 376 and the seventh guide groove portion 377, and reaches the "sensor insertion corresponding position 378a" of the eighth guide groove portion 378. When the guided element 39a reaches the "sensor insertion corresponding position 378a," the control device stops the lowering of the lifting arm 36. At this time, the plug pushing portion 5b of the sensor arm 5 pushes the plug mounting member 21 downward, so that the tip portion of the DO sensor 4 (DO electrode 4b) is inserted into the opening 17a of the lid portion 17 of the cleaning water container 2, which has been opened (ST36).

[0084] The control device cleans the tip of the DO sensor 4 by inserting the tip (DO electrode 4b) of the DO sensor 4 into the cleaning water container 2 for a certain period of time (ST37), and after the certain period of time has elapsed, drives the electric motor 31 of the electric jack device 35 to raise the lifting arm 36. As the lifting arm 36 rises, the sensor arm 5, supply arm 11, and drum 38 also rise (ST38), and the guided element 39a starts from the "sensor insertion corresponding position 378a" of the eighth guide groove 378, and passes through the seventh guide groove 377, the sixth guide groove 376, the ninth guide groove 379, and the third guide groove 373. Then, when the guided member 39a reaches the "origin position S" of the fourth guide groove portion 374, information informing the arrival is sent from a predetermined position detection sensor to the control device, and the control device immediately stops the lifting operation of the lifting arm 36 of the electric jack device 35.

[0085] Finally, the control device performs a process to drain the cleaning water in the cleaning water container 2 placed at the treatment position from the container 2 (ST39). Specifically, the cleaning water in the cleaning water container 2 is drained by switching the on-off valve 20, which opens and closes the flow path of the drain pipe 19 connected to the bottom of the cleaning water container 2 placed at the treatment position, from a closed state to an open state.

[0086] According to the dissolved oxygen consumption measuring device 1 described above, the sample liquid, aeration air, and cleaning water are selectively supplied to the container 2 placed at the treatment position, so that the sample liquid, aeration air, and cleaning water can be supplied to the container 2 at the same location without moving the container 2, and the mechanism and structure for moving the supply nozzle 10 can be simplified. As a result, the device 1 can be easily made smaller.

[0087] Furthermore, by coaxially connecting drum 38, in which guide groove 37 is formed, to the axis that serves as the rotation center of sensor arm 5 and supply arm 11, and by slidably fitting guided element 39a, which is attached to guided element support portion 39 fixed to a stationary member, into guide groove 37, the lifting and rotating movements of sensor arm 5 and supply arm 11 can be mechanically linked, so that the lifting and rotating movements of sensor arm 5 and supply arm 11 can be performed by a single actuator (electric motor 42) without the need for multiple actuators. As a result, the device 1 can be made more compact.

[0088] Next, a biochemical oxygen consumption prediction method according to an embodiment of the present invention will be described. The biochemical oxygen consumption (BOD) prediction method of the present invention includes a step of measuring the dissolved oxygen consumption of a sample using a dissolved oxygen consumption measurement device 1. As will be described in detail in the Examples, it has been revealed that the dissolved oxygen consumption measured by the dissolved oxygen consumption measurement device 1 shows a high correlation with the BOD of the sample.

[0089] A biochemical oxygen consumption prediction method according to one embodiment includes the steps of supplying a sample liquid to a container (2) via a sample liquid supply flow path (7), aerating the sample liquid by supplying air to the container (2) via an air supply flow path (8), measuring the change in the amount of dissolved oxygen in the aerated sample liquid within a predetermined period using a dissolved oxygen (DO) sensor (4), and predicting the BOD of the sample liquid based on the measured amount of dissolved oxygen.

[0090] In the step of supplying sample liquid to container 2 via sample liquid supply channel 7, sample liquid stored in bottle 26 is supplied into container 2 via supply nozzle 10. In the subsequent step, aeration air is supplied to the sample liquid in container 2 via air supply channel 8. In this step, it is sufficient that the amount of dissolved oxygen in the sample liquid is saturated or close to saturated by aeration, and aeration conditions such as aeration amount and aeration time can be adjusted as appropriate, but from the perspective of time reduction, a shorter aeration time is preferable. Specifically, the aeration time can be 300 to 1000 seconds, or 400 to 600 seconds.

[0091] In the next step, the change in the amount of dissolved oxygen in the aerated sample liquid over a predetermined period of time is measured using the DO sensor 4. As described above, the DO sensor 4 is provided with a tapered plug 4c on the outer periphery of the body 4a, the diameter of which decreases downward, and the plug 4c can fit snugly into the opening 17 of the container 2, so that measurement using the DO sensor 4 is performed when the container is filled with the sample liquid and in an airtight state. Therefore, the amount of dissolved oxygen in the sample liquid can be accurately measured in an environment free from the effects of oxygen in the air.

[0092] The change in dissolved oxygen, i.e., the dissolved oxygen consumption, can be calculated by subtracting the dissolved oxygen amount obtained at the end of the measurement from the dissolved oxygen amount obtained at the start of the measurement. The measurement time for dissolved oxygen consumption is preferably as short as possible, as long as it allows for prediction of BOD. Specifically, the measurement time can be 5 minutes to 3 hours, 15 minutes to 2.5 hours, or 30 minutes to 2 hours.

[0093] In the step of predicting the BOD of the sample liquid based on the measured dissolved oxygen consumption, the predicted BOD value can be obtained by converting the dissolved oxygen consumption into a BOD value using a preset approximation formula. The dissolved oxygen consumption is the amount of dissolved oxygen consumed within a certain period of time, and may also be the dissolved oxygen consumption rate. [Example]

[0094] The BOD prediction method using the dissolved oxygen consumption measuring device 1 will be described in more detail with reference to examples. The correlation between dissolved oxygen consumption and BOD value was clarified using six sample liquid specimens with BOD values ​​ranging from 9 to 123 mg / L. The sample liquid was supplied to a container 2 and aerated for 10 minutes. After aeration, the temperature of the sample liquid was 20°C, and the DO was 9.08 ± 0.12 mg / L (mean ± standard deviation), and the dissolved oxygen levels in all sample liquids were close to saturation.

[0095] Using the DO sensor 4, the amount of dissolved oxygen in the sample solution was measured at the start, 30 minutes, 60 minutes, and 120 minutes after the container 2 was filled with the sample solution and kept airtight. The dissolved oxygen consumption rate (mg / L / hour) was calculated after 30 minutes, 60 minutes, and 120 minutes, and the correlation with BOD was examined. The results are shown in Table 1. The coefficient of determination (R 2 The BOD values ​​exceeded 0.5 in all cases, and an extremely high correlation of 0.8 or more was obtained between the consumption rate and BOD after 60 minutes and 120 minutes in particular. From the above, it was demonstrated that by measuring the dissolved oxygen consumption of a sample liquid using the dissolved oxygen consumption measuring device 1, the BOD value of the sample liquid can be predicted in an extremely short time and with extremely high accuracy.

[0096] [Table 1] [Explanation of symbols]

[0097] 1. Dissolved oxygen consumption measuring device 2 containers 4 DO sensor (dissolved oxygen sensor) 4a Torso 4c Stopper 5 Sensor arm 7. Sample liquid supply channel 8 Air supply passage 9. Cleaning water supply channel 10 supply nozzle 11 Supply Arm 12 Arm drive means 13 Control box 15 Turntable 17a opening

Claims

1. A container and a sample liquid supply flow path for supplying the sample liquid; an air supply flow path for supplying aeration air; a supply nozzle that supplies fluid selectively supplied from the sample liquid supply channel and the air supply channel into the container; a dissolved oxygen sensor for detecting the dissolved oxygen concentration of the sample liquid supplied to the container; A dissolved oxygen consumption measuring device comprising:

2. A plurality of the containers are provided, a sensor arm that holds the dissolved oxygen sensor; a supply arm that is integral with the sensor arm and that holds the supply nozzle; an arm driving means capable of moving the sensor arm and the supply arm between a sensor insertion position where the dissolved oxygen sensor is inserted into one of the containers arranged at a specific position and a nozzle insertion position where the supply nozzle is inserted into one of the containers arranged at the specific position; Equipped with The dissolved oxygen consumption measuring device according to claim 1 .

3. A tapered opening that decreases in diameter downward is formed on the upper surface of the container, A tapered plug having a diameter that decreases downward is provided on a body portion of the dissolved oxygen sensor, When the sensor arm is disposed at the sensor insertion position, the plug fits snugly into the opening of the container, sealing the container. The dissolved oxygen consumption measuring device according to claim 2 .

4. a turntable that holds a plurality of the containers in a circular arrangement at predetermined intervals; a turntable driving means for driving the turntable to rotate; a control device; The control device a first positioning means for positioning one of the plurality of containers at the specific position via the turntable driving means, and then positioning the supply arm at a nozzle insertion position via the arm driving means; a sample liquid / air supplying means for supplying a sample liquid into the container placed at the specific position and for supplying aeration air into the container placed at the specific position; a second positioning means for positioning the sensor arm at a sensor insertion position via the arm driving means; a detection means for detecting a dissolved oxygen concentration based on output information from the dissolved oxygen sensor; a measuring means for measuring the amount of dissolved oxygen consumed based on the dissolved oxygen concentration detected by the detecting means; having The dissolved oxygen consumption measuring device according to claim 3.

5. Further provided is a cleaning water supply flow path for supplying cleaning water; the supply nozzle supplies fluids selectively supplied from the sample liquid supply channel, the air supply channel, and the cleaning water supply channel into the container; The dissolved oxygen consumption measuring device according to claim 1 .

6. A method for predicting biochemical oxygen consumption using the dissolved oxygen consumption measuring device according to any one of claims 1 to 5, providing a sample liquid to the container; aerating the sample liquid in the container; measuring the change in the amount of dissolved oxygen in the aerated sample liquid over a predetermined period of time; predicting the biochemical oxygen consumption of the sample liquid based on the change in the amount of dissolved oxygen; Including, Biochemical oxygen consumption prediction method.

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