JP2000146893A - Bod measuring instrument and bod measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the clogging or contraction of a test water introducing passage and perform a smooth BOD measurement by introducing and supplying a fixed quantity of test water from a test water source through a test water passage, providing a filter mesh for filtering the test water, and supplying a detergent to the filtering surface. SOLUTION: A flow cell 3 has a microorganism electrode part 2, and a liquid inlet 31 and a liquid outlet 32, which are arranged so that a liquid passing between them makes contact with the microorganism electrode 2. A test water passage 4 connects the liquid inlet 31 to a test water source S through a test water tank 41 for temporarily storing test water. A test water supplying part 5 introduces the test water from the test water source S through the test water passage 4 and supplies a fixed quantity thereof to the flow cell 3. A test water filtering filter mesh 6 is arranged between the test water inlet side and test water dispensing side of the test water tank 41. A detergent is supplied from a detergent supplying part 7 to the filtering surface 6a of the filter mesh 6, whereby impurities adhered to the filtering surface 6a are decomposed and removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a BOD measuring device and a BOD measuring method by a microbial electrode method, and more particularly, to a microbial electrode by preventing clogging of a test flow channel due to impurities contained in a test water. The present invention relates to a BOD measuring instrument and a BOD measuring method improved to maintain and secure the quantitativeness of a sample to be introduced.

[0002]

2. Description of the Related Art In a biochemical oxygen demand (BOD) measuring device using a microbial electrode, a microbial electrode section is usually provided.
A flow cell having a liquid inlet and a liquid outlet and having a liquid passing therethrough arranged in contact with the microbial electrode, a test fluid connected to the liquid inlet of the flow cell, a buffer,
A flow path for introducing a liquid for introducing a standard solution, washing water, etc. into the flow cell, and a test water supply unit, for example, a pump, capable of introducing a test water from a test water source through the flow path and quantitatively supplying the flow cell, The amount of dissolved oxygen consumed by the metabolism of microorganisms in water is detected as the output of the electrode, and the BOD value is measured.

[0003] The BOD value of a test water is measured based on the output when washing water (for example, water) is supplied to a flow cell, and one or two or more standard liquids containing an organic substance containing a known BOD. Output from output when liquid is supplied-
It is performed by calibrating the concentration conversion and then supplying the test water. When supplying water to the flow cell,
The buffer is simultaneously supplied to the flow cell to adjust the pH and the like. The supply of the standard solution and the test water is performed through a washing step of supplying washing water to a flow path for introducing each of these liquids to a flow cell provided with a microbial electrode.

[0004] BOD measurement is generally used to monitor trends in raw water, intermediate treated water, effluent water, and the like in various treatment facilities. Such sampling of water sampled on site is performed by a preset sampling program. For example, based on
This is done on a regular basis or when receiving or releasing raw water. Furthermore, due to demands for labor saving and unmanned operation, an automatic measuring instrument has been used for BOD measurement in recent years.

[0005] In such a BOD measuring instrument, particularly a BOD automatic measuring instrument premised on unmanned operation, it is necessary to prevent the introduction flow path of the water sample or the like reaching the flow cell from being clogged by impurities mixed with the water sample. A filter net is provided at the entrance of the sample introduction pipe. Some filter nets simply cover the inlet to the flow cell with absorbent cotton or nonwoven fabric, and are replaced before clogging occurs or when clogging occurs. Such manual maintenance of the filter net is easy, but the filter net is easily clogged and requires frequent replacement.

In the case of unmanned measurement, a roll-type filter paper that can be wound up sequentially is used in order to avoid blockage of the flow channel due to clogging and maintenance of the filter net by hand. One that performs backwashing with air pressure is used.

[0007]

SUMMARY OF THE INVENTION In replacing a filter net,
In the case of using the above-mentioned roll-type filter paper, although reliable filtration can be performed, there is a problem that the entire apparatus including the winding mechanism becomes large and complicated, and the running cost increases. On the other hand, those that perform backwashing can be operated for a long period of time for water samples with a relatively small degree of dirt, but can be used for samples with relatively large degrees of dirt, such as raw water from sewage treatment plants. Is not sufficiently effective in backwashing, making continuous operation difficult. Also, even if the sample introduction flow path does not completely clog, if the contaminants attached to the filter net or the like become constricted, the amount of sample supplied to the flow cell decreases, and the BOD decreases.
This may cause an error in the measured value.

[0008] The present invention has been made in view of the above problems, and an object thereof is to prevent clogging and narrowing of a flow path for introducing a sample to enable smooth BOD measurement. It is to provide a BOD measuring device and a BOD measuring method.

[0009]

According to the present invention, FIG.
As shown in FIG. 1, the liquid having the microbial electrode part 2, the liquid inlet 31 and the liquid outlet 32,
A flow cell 3 disposed so as to be in contact with the water sample, a test water tank 4 for temporarily storing the test water, and a test water flow path 4 connecting the liquid inlet 31 of the flow cell 3 and the test source S via the water test tank 41;
A test water supply unit 5 capable of introducing a test water from the test water source S through the test water flow path 4 and supplying a fixed amount to the flow cell 3 is provided between the test water introduction side and the test water intake side of the test tank 41. A BOD measuring device 10 comprising a filter net 6 for water filtration and a detergent supply unit 7 for supplying a detergent to a filtration surface 6a of the filter net 6 is provided.

That is, according to the present invention, the test water is passed through the filter net 6 in the water test tank 41 provided between the test water source S and the liquid inlet 31 of the flow cell 3 to remove impurities. When the test water is supplied to the flow cell 3, by supplying the detergent to the filtration surface 6 a of the filter net 6, impurities adhered to the portion of the filtration surface 6 a to which the detergent has been supplied are decomposed and removed,
Thus, the filter surface 6a is formed with a portion through which water can pass, thereby preventing clogging of the filter net 6, and stably supplying a predetermined amount of water required for BOD measurement to the flow cell 3. it can.

The BOD measuring instrument in the present invention is, for example, a measuring instrument conforming to JIS K 3602, in which a neutral buffer is allowed to flow in a flow cell in contact with a microbial electrode section to maintain neutral conditions. Air is blown into the vessel to keep it under substantially air-saturated conditions. Under this condition, a sample is introduced to reduce the amount of dissolved oxygen in the cell corresponding to the BOD component in the sample, that is, the amount of dissolved oxygen consumed by metabolism of microorganisms. (BO
This is a measuring instrument for detecting and measuring D) as an output of a diaphragm oxygen electrode. The measurement target of the BOD measuring instrument includes raw water, intermediate treated water, effluent water, and the like of a sewage treatment plant, a food factory, a pharmaceutical factory, and the like.

The water sample in the present invention may be a water sample in a water sample container for storing the sampled water sample, or a water sample directly sampled from a tube placed in a treatment tank for raw water or the like. The water test flow path in the present invention is specifically a pipe, but the present invention includes a part of the flow path having an open channel, that is, a channel whose upper part is opened. In the present invention, the water test tank can be interposed at an arbitrary position in the water test flow path, and the position may be, for example, near the intake of the test source or near the liquid inlet of the flow cell.

The test water supply section in the present invention is a mechanism section having a drive source for supplying test water from the test water source to the flow cell via the test flow path, and having a quantitative property with respect to the test water supply. Specific examples include a pump such as a tubing pump and a syringe pump and a control unit therefor. The present invention also includes a configuration in which a valve and a pump are provided in the water test flow path, and the test water is taken into the flow cell by opening and closing control of the valve. The filter net in the present invention has a mesh diameter smaller than the length of each side in the pipe diameter or the rectangular cross section of the water test flow path, and although it depends on the type of water test, usually, a screen of about 20 mesh is preferable. . Examples of the shape of the filter net include a filter in which the entire filtration surface is on the same plane, and a filter formed in a continuous “C” shape in order to increase the filtration surface with respect to the cross section of the test water flow channel.

Examples of the detergent in the present invention include those containing an alkaline detergent for immersion and an enzyme detergent which have a proteolytic / removing effect, and an appropriate detergent is selected and used according to the type and properties of the water sample. be able to. The form of the detergent
A liquid is preferred, but a gel may be used. The detergent supply unit in the present invention may be a unit having a mechanism for spraying the detergent at a predetermined pressure from the detergent discharge port facing the filter net, or a unit for dropping the detergent onto the filter net by a pump or gravity. The detergent may be supplied to at least a part of the filtration surface of the filter net, and does not necessarily need to be supplied uniformly over the entire filtration surface.

In the BOD measuring device according to the present invention, the water supply unit has liquid sending means for transporting the water sample stored in the water tank to the liquid inlet of the flow cell, and the detergent supply unit has a filter net at the tip. Having a detergent discharge port disposed at a position facing the filtration surface of the above.

The test tank is a primary tank for sediment receiving the test water, a secondary tank connectable to the liquid feeding means, and a filter net for dividing the primary tank and the secondary tank so that these two tanks communicate with each other. Is provided with a fixing means for detachably fixing the sample, the test sample from which impurities are removed by the filter net and the sediment removed by the primary tank can be supplied to the flow cell. The fixing means of the filter net in the present invention means that the filter net can be fixed in the test water flow path against the pressure of the test water passing through the filtration surface of the filter net, and the filter net is replaced for maintenance such as replacement of the filter net. Is preferable, and examples thereof include a structure in which the filter net can be fixed such that the filtration surface extends substantially vertically or substantially horizontally. The position where the fixing means is disposed is preferably a position where the filter net is immersed in the water test tank by the water test once stored.

The test tank is connected to a wash water supply unit capable of supplying wash water into the test tank, and further has a test discharge valve for discharging the test water stored in the test tank, and the test discharge valve is opened. After the detergent is supplied, the detergent supply unit supplies the detergent to the filter surface of the filter net exposed in the water test tank, and the washing water supply unit supplies the detergent to the filter surface of the filter net and then cleans the water in the test tank. With a configuration in which water is supplied, the filter net can be pickled and washed with the detergent and the washing water added thereafter.

The liquid feeding means moves relatively between the secondary tank and the washing water tank arranged adjacent to the secondary tank, so that the test water in the secondary tank and the washing water in the washing water tank are moved. If the pipette has a pipette capable of selectively separating the sample, the water test channel can be easily and sufficiently washed. The pipette according to the present invention is a suction pipe having a liquid suction port at a distal end, and a pipette moving mechanism or a sample moving mechanism configured to support a base end side and relatively move between a water test tank and a washing water tank. Those with a mechanism are preferred.

As the pipette moving mechanism, for example, a pair of pulleys, a belt stretched over the pulleys, a pivot shaft formed on the main surface of each pulley, and upper and lower ends supported by the respective pivot shafts. A moving element, a sorting tube fixed to the moving element, a stepping motor for rotatingly driving the upper driving pulley, and a sensor for positioning the sorting tube; the pulley is controlled at a predetermined angle by controlling the stepping motor. When rotating the range in both directions, the sorting tube fixed to the mover holds its longitudinal axis up and down,
There is a mechanism capable of reciprocating between a moisture detection position above the water tank and a washing water suction position above the washing water tank. Also,
The sample moving mechanism includes, for example, a rack for storing a plurality of water containers and liquid containers such as washing water, a turntable on which the rack is mounted and rotatable on a horizontal plane, and moving the turntable up and down. And a mechanism for moving the rack vertically and horizontally so that the tips of the fixed pipettes can alternately exist in the test tank and the washing tank.

If the filter net is provided in front of the water sample tank so that the water sample that has passed through the filter net can be received in the water sample tank, for example, the filter net is placed above the water sample collecting tank, It is possible to introduce a test water from above the filter net, and thereby, it is possible to separate the foreign substances adhering to the filter net from the test water introduced into the test water collecting tank, and to detect the foreign substances. Decomposition and dispersion with water can be prevented. Further, by arranging the filter net so that the filtration surface is substantially horizontal, it is possible to uniformly supply the detergent to the entire filtration surface from above using, for example, a shower nozzle or the like.

If the detergent supply section comprises a detergent tank, a detergent pipe connecting the detergent tank and the detergent outlet, and a detergent pump interposed in the detergent pipe, the detergent pump is controlled. To provide an accurate amount of detergent. The detergent supply unit may be configured to include a detergent tank for storing the detergent, a detergent tube connecting the upper detergent tank and the lower detergent discharge port, and an opening / closing valve interposed in the detergent tube. For example, the detergent can be supplied to the filter net with a simple configuration that only controls the opening and closing of the opening and closing valve.

If the filter net is made of a fluorine-based resin as a part of the material, it becomes difficult for stains to adhere to the filter net. Examples of the fluororesin used for forming the filter net include polytetrafluoroethylene (PTFE), tetrafluoroethylene / perfluoroalkylvinyl ether copolymer (PFA), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), Tetrafluoroethylene / ethylene copolymer (ETFE), polychlorotrifluoroethylene (PCTFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. No.

According to another aspect of the present invention, as shown in FIG.
When measuring the BOD of the test water using the BOD measuring device 10 having the flow cell 3 disposed so that the liquid passing therethrough is in contact with the microbial electrode part 2, the flow cell 3 It is assumed that the test water supplied to the liquid inlet 31 is passed through the filter net 6 between the test water inlet side and the test water intake side of the water test tank 41, and the detergent is supplied to the filtration surface 6a of the filter net 6. A BOD measurement method for characteristic water sampling is provided.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 shows a BOD measuring device according to one embodiment of the present invention. The BOD measuring device 10 basically includes a microbial electrode portion 2, a flow cell 3 having a liquid inlet 31 and a liquid outlet 32, and a liquid passing therethrough and arranged so as to be in contact with the microbial electrode 2. A test channel 4 for connecting the liquid inlet 31 to the test source S; a test supply unit 5 capable of introducing a test sample from the test source S via the test channel 4 and supplying a fixed amount to the flow cell 3; A filter net 6 for water sample filtration provided in
A detergent supply unit for supplying a detergent to a filtration surface of the filter net; The microorganism electrode 2 is configured to transmit an output signal to a measurement recording unit (not shown). Flow cell 3
It is housed inside a constant temperature chamber (not shown).

The test water flow path 4 includes an adjacent test water tank 41 and a cleaning water tank 42, and a pipe 4 connecting the water test source S and the water test tank 41.
3 and a pipette 8 having a distal end movable between a test water tank 41 and a washing water tank 42, and a pipe 45 connecting the base end of the pipette 8 and the liquid inlet 31 of the flow cell 3. The pipe 43 is provided with a sample pump 44 for sucking sample water from the sample source S and supplying it to the sample tank 41.

The pipe 45 is provided with a pipette suction pump 46.
A standard liquid supply unit 47 is branched and connected to a pipe portion between the base end of the pipette 8 and the pipette suction pump 46, and a pipe line between the pipette suction pump 46 and the liquid inlet 31. A buffer solution supply section 48 and an aeration air supply section 49 are branched and connected to the portion. The standard liquid supply unit 47 includes a standard liquid collecting pipe 47a, standard liquid tanks 11, 12, 13, electromagnetic valves 14, 15, 16 and electromagnetic valves 14, 15, 16 via the standard liquid tank 11. , 12, and 13 are connected to the standard liquid collecting pipe 47 a.
Consists of Each of the standard liquid tanks 11, 12, and 13 has a BOD
Three standard solutions consisting of known organic substance-containing solutions, for example,
Mixtures A, B, and C, in which a mixture of glutamic acid and glucose at an equal concentration was adjusted to a BOD concentration of 25 mg / L, 50 mg / L, and 100 mg / L, respectively, were accommodated.

The buffer supply section 48 comprises a buffer tank 21, a buffer pump 22, and a buffer pipe 48a connecting the buffer tank 21 and the pipe 45 via the buffer pump 22. The air supply unit 49 for aeration includes an air pressure source 35 such as an air compressor, and an air supply line 49 a connecting the air pressure source 35 and the line 45. A flow path switching valve 51 for driving the pipette suction pump 46 to supply one of the sampled / washed water and the standard solution to the flow cell 3 is provided in the above-described conduit 45. ing.

FIG. 2 shows the structure of the pipette 8 which forms a test water supply section together with the water test tank 41, the washing water tank 42, and the pump 46. In FIG. 2 shown in a sectional view, the water test tank 41 includes a primary tank 110 for sediment, and a secondary tank 120 connected to the primary tank 110 via the filter net 6. Primary tank 110
Is provided with an inflow port 111 into which a sample flows and a bottom discharge port 112, and the secondary tank 120 is provided with a bottom discharge port 1
21 and an upper overflow port 123. The inflow port 111 is connected to the pipe 43 described above.

The filter net 6 includes a primary tank 110 and a secondary tank 120
Is fixed in a state where the filtration surface 6a is erected so as to be substantially vertical by fixing means for detachably fixing the filter net so that these two tanks communicate with each other. The filter net 6 is made of polytetrafluoroethylene (PTFE) and
Molded into mesh. The fixing means is constituted by frames 61 respectively disposed on the inner surfaces on the opposite side of the water test tank 41, and the filter net 6 is inserted inside the frame 61. Frame 6
The filter net 6 inserted into the pipe 1 is erected with the same height as the lower end of the inflow port 111 or an upper end higher than the lower end, and sludge (contaminants) in the test water flowing into the primary tank 110 from the inflow port 111. Is prevented from flowing out to the secondary tank 120.

Further, the washing tank 42 is adjacent to the secondary tank 120 via a partition wall 122. The washing water tank 42 is provided with a washing water inflow port 102 and a discharge port 103 at the bottom, and the washing water remaining in the washing water tank 42 can be drained from the drain port 103 and exchanged during the water detection. As shown in FIG. 1, the cleaning water inflow port 102 is provided with a cleaning water pump 56 in a cleaning water tank 55 for storing cleaning water (tap water or a tap water to which a detergent may be added).
Are connected by a pipe 57. Discharge port 11
Opening and closing of 2, 121 and 103 are performed via electromagnetic valves 52, 53 and 54 connected below the respective ports.

The overflow port 123 is connected to the secondary tank 1
The upper end of the overflow port 123 is located below the upper end of the partition wall 122, the lower end of the overflow port 123 is located below the lower end of the inflow port 111, and A dispensing pipe 8 described below at a moisture detection position in the tank 120.
It is located above the position of one tip 81a. With such a configuration of the overflow port 123, the water detection tank 41
After the previous sample stored in the tank is discharged from the discharge ports 112 and 121, new sample is introduced from the inflow port 111 into the primary tank 110 and the secondary tank 120 until the new sample overflows from the overflow port 123, and the sample is detected. The water sample in the water tank 41 can be completely replaced with a new water sample. Above the partition wall 122, the pipette 8 is arranged.

The pipette 8 includes a pair of upper and lower pulleys 91 attached to a base 90, a belt 92 stretched over the pulleys 91, a pivot shaft 93 formed on the main surface of each pulley 91, A moving member 94 whose upper and lower ends are supported by a pivot shaft 93, a sorting tube 81 fixed to the moving member 94, a stepping motor 96 for rotatingly driving the upper driving pulley 91, and a photo for positioning the sorting tube 81. It comprises sensors 97 and 98. The pivot shaft 93 is connected to the hole 9 of the moving element 94 via a roller bearing (not shown).
4a. When the pulley 91 is rotated bidirectionally in the angular range indicated by the arrow R in the figure by the stepping motor 96, the moving element 94 is held above the secondary tank 120 (in the figure, with its longitudinal axis held vertically). It is possible to reciprocate between a portion (solid line) and a portion above the partition wall 122 (broken line in the drawing) to a portion above the washing water tank 42 (dashed line in the drawing).

Therefore, the sorting tube 81 fixed to the moving element 94 has the tip 81a having a circular arc as a trajectory between the moisture detection position inside the secondary tank 120 and the washing water suction position inside the washing water tank 42. A reciprocating semicircular movement can be performed. Each of the photosensors 97 and 98 includes a pair of a light emitting diode and a phototransistor.
When a is located at the moisture detection position and the washing water suction position, the position of the pivot shaft 93 of the corresponding pulley 91 is detected. Above the filter net 6, a detergent supply unit 7
Are provided. Detergent outlet 71
The front end of the filter net 6 is disposed at a position facing the filtration surface 6a of the filter net 6 fixedly installed in the water test tank 41, and the other base end side contains a detergent as shown in FIG. The used detergent tank 72 is connected to a detergent pipe 74 connected via a detergent pump 73. The detergent tank 72 contains, for example, a liquid detergent containing an alkaline detergent.

Each of the above-described electromagnetic valves and pumps and the pipette 8 are electrically connected to a control unit (not shown), and the control unit instructs driving / stopping and opening / closing of each unit according to a preset program. An example of the operation of each unit in the BOD measuring device 10 based on a command from the control unit will be described below.

First, the initial setting such as the positioning of the distal end 81a of the sorting tube 81, the opening / closing state of the electromagnetic valve, etc. is performed, and the driving of the buffer pump 22 and the pneumatic source 35 is started. Is started, and at the same time, the electromagnetic valve 51 is opened for ta seconds. The washing water sucked from the tip 81a of the sorting tube 81 is introduced into the flow cell 3 for ta seconds, and the output when the passing washing water contacts the microbial electrode 2 is set as the base output. Next, the BO is supplied from the standard solution supply unit 47.
D. One or more standard solutions composed of a known organic substance-containing solution are introduced into the flow cell 3, and the output-BOD concentration conversion is calibrated from the output when the passing standard solution comes into contact with the microorganism electrode unit 2.

Specifically, after the electromagnetic valve 14 is opened for tA seconds to introduce the standard solution A, the electromagnetic valve 51 is opened for tb seconds to introduce washing water to wash the line. Next, after the electromagnetic valve 15 is opened for tB seconds and the standard solution B is introduced, the electromagnetic valve 51 is opened for tb seconds and washing water is introduced to wash the line. Next, after the electromagnetic valve 16 is opened for tC seconds and the standard solution C is introduced, the electromagnetic valve 51 is opened for tb seconds and washing water is introduced to wash the line.

Next, with the electromagnetic valves 52, 53 and 54 closed and the buffer solution pump 22, the pneumatic pressure source 35 and the pipette suction pump 46 continued to be driven, the water sample pump 44 is driven. The test water from the test water source S is introduced into the primary tank 110. Immediately before this, the washing water is supplied to the washing water tank 42 in the water inspection tank 41.
After overflowing into the test tank 41 from the
The cleaning water is discharged from the cleaning pipes 12 and 121 so that the cleaning water is washed in advance. Approximately 5 minutes after the introduction of water sampling, water sampling tank 41
Is filled with a new sample.

Next, the test water filled in the test water tank 41 is sucked from the tip 81a of the sorting pipe 81 moved to the water sampling position and supplied to the flow cell 3 (for 5 minutes). During this time, the output when the sample comes into contact with the microorganism electrode 2 is detected as the BOD concentration. When the preparative pipe 81 starts moving from the moisture detection position to the washing water suction position, the supply of the test water to the flow cell 3 is cut off, and the BOD concentration measurement of the target test water ends. At the same time as the distal end 81a of the fractionation tube 81 leaves the test liquid level, the electromagnetic valves 52 and 53 are opened to discharge the test water in the test tank 41.

During this time, the washing water is sucked from the tip 81a of the pipette 8 moved from the moisture detection position to the washing water suction position in the washing water tank 42, and the pipe 45 is washed.
The outer peripheral portion of the tip 81a of the pipette 8 immersed in the washing water is washed. When the discharge of the sample is completed about 5 minutes after the start of the discharge, the cleaning water pump 56 is driven to drive the cleaning water tank 55.
The cleaning water in the inside is supplied to the cleaning water tank 42 and overflows to the water testing tank 41 to clean the inside of the water testing tank 41.

Next, the detergent pump 73 is driven to supply the detergent liquid in the detergent tank 72 to the filter net 6 from the nozzle 71.
The liquid detergent is dropped on the filter net 6 continuously at 5 ml / min for about 2 minutes. The dropped detergent moves downward from the upper portion along the filter surface 6a of the filter net 6, and diffuses to the lower portion of the filter surface 6a. During this time, at least the filtration surface 6 to which the detergent has been supplied.
Impurities adhering to the portion a, for example, solids containing proteins and the like, which disturb the quantitative supply of the test water, are decomposed and removed. Thereby, the filtration surface 6a through which the water sample can pass is secured, and the clogging of the filter net 6 is prevented.

After the above-described detergent supply for about 2 minutes, the electromagnetic valves 52 and 53 are closed, and the cleaning water supplied to the cleaning water tank 42 overflows to the test tank 41, and the test tank 41 is filled with the cleaning water. The filter net 6 is left in a state of “dipping and washing” with the detergent and the washing water attached to the filtering surface 6 a in the water test tank 41 (about 13 minutes). This further decomposes and removes contaminants attached, including the portion of the filtration surface 6a to which the detergent has not directly spread.

After leaving for about 13 minutes in the state of “dipping and washing”, the electromagnetic valves 52 and 53 are opened to discharge the washing water filled in the test tank 41. Almost at the same time water sampling pump
Is driven to introduce a new sample from the sample source S into the primary tank 110 (for 5 minutes). At this time, the water test tank 41 is "washed" with new water test. After the electromagnetic valves 52 and 53 are closed, the BOD concentration of the new test water filled in the water test tank 41 is measured based on the same control operation as described above.

In the above embodiment, the detergent moves and diffuses downward along the filtration surface 6a of the filter net 6, so that the detergent
The detergent can be spread over a relatively wide range of a.
Further, since the detergent is directly dropped on the filtration surface 6a of the filter net 6, and the washing water supplied is left for a predetermined time in a state of “dipping and washing”, the filtration of the filter mesh 6 with the dropped detergent is performed. In the portion of the surface 6a, the communication between the primary tank 110 and the secondary tank 120 becomes more reliable, and the filtration surface 6a including the portion of the filtration surface 6a to which the detergent did not directly reach by "pickling and washing".
a can be uniformly washed. Thereby, the filter surface 6a through which the water sample can pass can be made larger, and the clogging of the filter net 6 is more reliably prevented.

Using a BOD measuring device 10, a comparative test was conducted on the relationship between the presence or absence of detergent supply to the filter net and the material of the filter net for clogging of the filter net. According to the conventional method, no detergent is supplied to the filter net, and the material of the filter net is stainless steel (SUS304).

Test Example Test conditions are shown below. Target water sample: Inflow from sewage aeration tank, water injection time: 5 minutes, water line cleaning time: 25 minutes, calibration standard solution: 25 mg / L 5
0 mg / L 100 mg / L BOD standard solution (JIS K 3602), calibration frequency 12 times / day, filter net: 20 mesh SUS304 net and PTFE net, detergent: liquid detergent (PH 11)], water tank capacity: 1
50 ml, detergent dripping amount: 1.5 ml / time The filter net is completely closed, and the amount of water required for BOD measurement (15
ml or more) could not be secured in the secondary tank. Table 1 shows the results.

[0046]

[Table 1]

From the above test results, when the detergent is not supplied to the filter net, clogging of the filter net is fast regardless of the material of the filter net, but when the detergent is supplied, the filter net is clogged. It can be seen that it is suppressed and the securing of the amount of water sample in the secondary tank becomes better. Further, it can be seen that the fluorine resin (PTFE) mesh is less likely to adhere to the stain than the stainless steel (SUS304) mesh.

Another Embodiment FIG. 3 shows a water test tank according to another embodiment of the present invention.
The structure of the washing water tank, the fixing means of the filter net, and the detergent discharge port is shown. In this example, the filter net is placed in front of the test tank so that the test water passing through the filter net is received in the test tank. That is, the water test tank 141 and the wash water tank 142 are basically similar to the test water tank 41 and the wash water tank 42 described above, but are constituted by a flange 161 provided with a fixing means for the filter net 6 above the primary tank 110. The difference lies in that the filter screen 6 is detachably fixed so that the filtration surface 6a is substantially horizontal, and that the detergent discharge port of the detergent supply unit 7 is constituted by a perforated shower nozzle 76. In this case, if the position of the overflow port 223 is set above the figure, the pickling of the filter net 6 can be performed.

FIG. 4 shows the structure of a detergent supply unit according to another embodiment of the present invention. In this example, the detergent supply unit 7 includes a detergent tank 172 for containing a detergent, and a dripping pipe 171 adjusted so that the detergent contained in the detergent tank 172 drops from the detergent discharge port by gravity. The drip line 171 is connected to an elastic tube 174 having one end connected to the lower portion of the detergent tank 172, a nozzle 175 connected to the other end of the elastic tube 174, and the nozzle 175 from the detergent tank 172 side of the elastic tube 174. And an electromagnetic valve 176 and a detergent flow control valve 177 disposed in the elastic tube 174 in this order. The detergent flow control valve 177 includes a valve case 178 and a valve case 1.
A roller 179 skews the inside 78 and presses the elastic tube 174 housed in the valve case 178, and the flow rate is set in advance by adjusting the position of the roller 179. Then, by controlling the opening and closing of the electromagnetic valve 176, a predetermined amount of detergent can be supplied to the filtration surface 6a of the filter net 6 at a predetermined timing.

[0050]

In the BOD measuring device according to the present invention, the test water is passed through a filter net in a water test tank provided between the test water source and the liquid inlet of the flow cell to remove impurities. By supplying detergent to the filtration surface of the filter net when supplying water to the flow cell, impurities adhering to the filtration surface are decomposed and
By being removed, the filter surface can be prevented from clogging by securing a filtration surface through which the test water can pass, and a predetermined amount of test water required for BOD measurement can be stably supplied to the flow cell.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a BOD measuring device according to one embodiment of the present invention.

FIG. 2 is a front view of one embodiment of a fixing means of a water test tank, a washing tank, a pipette, and a filter net of FIG. 1;

FIG. 3 is a front view showing the configuration of a water test tank, filter net fixing means, and a detergent discharge port according to another embodiment of the present invention.

FIG. 4 is a front view of a detergent supply unit according to another embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 2 Microbial electrode 3 Flow cell 4 Test flow channel 5 Test water supply unit 6 Filtration net 6a Filtration surface 7 Detergent supply unit 8 Pipette 81a Pipette tip 10 BOD meter 31 Liquid inlet 32 Liquid outlet 41 Test tank 42 Wash tank 46 For pipette suction Pump 71 Detergent outlet 81 Preparative tube

Claims (10)

[Claims] 1. A detection system comprising a microbial electrode part, a flow cell having a liquid inlet and a liquid outlet and having a liquid passing therethrough arranged in contact with the microbial electrode part, and a test tank for temporarily storing test water. A test channel for connecting the liquid inlet of the flow cell to the test source via a water tank, a test supply unit capable of introducing a test sample from the test source via the test channel and supplying a fixed amount to the flow cell; A BOD measuring device comprising: a filter net for water filtration provided between a water introduction side and a moisture detection side; and a detergent supply unit for supplying a detergent to a filtration surface of the filter net. . 2. The test water supply unit has a liquid sending means for conveying the test water stored in the water test tank to the liquid inlet of the flow cell, and the detergent supply unit is disposed at a position where the tip faces the filtration surface of the filter net. The BOD measuring device according to claim 1, further comprising a detergent discharge port provided. 3. A test tank, which divides a primary tank for sediment receiving a test water, a secondary tank connectable to a liquid sending means, a primary tank and a secondary tank, and communicates these two tanks. 3. The BO according to claim 2, further comprising fixing means for detachably fixing the filter net.
D measuring instrument. 4. The test tank is connected to a wash water supply unit capable of supplying wash water into the test tank, and further includes a test water discharge valve for discharging the test water stored in the test tank. ,
After the sample discharge valve is opened, the detergent is supplied to the filter surface of the filter net exposed in the test tank, and the washing water supply unit is supplied with the detergent on the filter surface of the filter net, and then the detergent is supplied into the test tank. The BOD measuring device according to any one of claims 1 to 3, which supplies cleaning water. 5. A liquid sending means relatively moves between a secondary tank and a washing water tank arranged adjacent to the secondary tank to measure water in the secondary tank and to wash the washing water in the washing tank. The BOD measuring device according to any one of claims 1 to 4, further comprising a pipette capable of selectively separating water and water. 6. The filter net is provided in front of the test tank so that the test water passing through the filter net is received in the test tank.
Or the BOD measuring instrument according to 2. 7. The detergent supply unit according to claim 1, further comprising a detergent tank, a detergent tube connecting the detergent tank and the detergent discharge port, and a detergent pump interposed in the detergent tube. The BOD measuring device according to any one of the above. 8. A detergent supply unit comprising: a detergent tank for containing a detergent; a detergent tube connecting an upper detergent tank and a lower detergent discharge port; and an opening / closing valve interposed in the detergent tube. The BOD according to any one of claims 1 to 6, comprising:
Measuring instrument. 9. The filter network according to claim 1, wherein the filter net is made of a fluororesin.
9. The BOD measuring instrument according to any one of items 1 to 8. 10. A BOD measuring apparatus using a BOD measuring device including a microbial electrode unit and a flow cell having a liquid inlet and a liquid outlet and having a liquid passing therethrough and arranged in contact with the microbial electrode unit. When measuring the water content, the test water supplied from the test water source to the liquid inlet of the flow cell is passed through the filter net between the test water introduction side and the water test water intake side of the test tank, and the detergent is passed through the filter surface of the filter net. Water BOD characterized by supplying water
Measurement method.