JP2010160169A - Apparatus and method for detecting abnormality in water quality - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for detecting an abnormality in water quality which prevents the generation of bubbles in a measuring tank, keeps the temperature of water to be tested within a predetermined range, and therefore prevents a false warning of "abnormality in water quality" from being caused by bubbles and/or low temperatures. <P>SOLUTION: The apparatus for detecting the presence or absence of an abnormality in the quality of water to be tested while keeping the temperature of the water to be tested within a predetermined temperature range includes a water temperature adjustment device for supplying a temperature-adjusting water into an area around an introduction pipe through which the water to be tested is introduced, the temperature-adjusting water having been controlled so that its temperature is close to the temperature range, and for approximating the temperature of the water to be tested to the temperature of the temperature-adjusting water by transfer of heat through the introduction pipe. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an abnormal water quality detection apparatus and an abnormal water quality detection method for detecting the presence or absence of an abnormality in the water quality while maintaining the test water in a preset temperature range.

  Conventionally, in a water treatment plant, river water or the like is taken as a normal treatment, and this water is passed through a sedimentation filtration tank to supply drinking water. If harmful substances that cannot be removed by such normal treatment, such as various heavy metals, agricultural chemicals, and environmental hormones, are mixed in the river water, an emergency situation will occur where water intake is stopped.

  On the other hand, in a sewage treatment plant, due to sudden accidents or carelessness, various heavy metal ions, organic solvents, arsenic cyanide, etc. are mixed in the wastewater of factories or chemical plants. As a result, the activity of the activated sludge is reduced, and a great deal of time is required until the treatment capacity is restored.

  Therefore, there has been a demand for a device that detects inflow water quickly and with high sensitivity when the above-mentioned various harmful substances are mixed in water purification plants and sewage treatment plants.

  In response to this demand, a fish behavior monitoring type poison detection device or a device for detecting a poison from the measurement of respiratory activity by attaching various microbial membranes to a dissolved oxygen electrode is used at a water purification plant. In the sewage treatment plant, various sensors that detect wastewater mixed with a specific chemical substance are installed at each water intake.

  Among these, the fish activity monitoring type poison detection device installed in the water purification plant takes a long time for the fish to react with the poison, so that a long time is required for the detection. In addition, the reaction sensitivity of fish varies considerably depending on the type of fish being bred, individual differences, and the environmental conditions of the breeding. Furthermore, the fish behavior monitoring-type poison detection device has a problem that the device itself is large and the cost for raising and managing fish is high.

  Accordingly, biosensor-type abnormal water quality detection devices have been developed. As an example, there is one that uses an iron-oxidizing bacterium that can be operated at a relatively low pH value where toxic substances and bacteria are difficult to propagate as a probe (see, for example, Patent Document 1).

  In this biosensor-type water quality monitoring apparatus, first, water to be examined is diffused with air or a gas whose oxygen concentration is adjusted to be constant in an aeration water tank so that the dissolved oxygen concentration is saturated. A ferrous sulfate-containing solution is supplied to the test water thus prepared and mixed with the test water. This mixed solution flows into the measurement tank in a state where the dissolved oxygen concentration is saturated.

  The measurement tank is provided with an oxygen electrode, but the test water is always kept at the saturated dissolved oxygen concentration by supplying air or a gas whose oxygen concentration is adjusted to be constant, so that the maximum value of the output of the oxygen electrode is stabilized. The oxygen electrode is provided with a microbial membrane attached to the tip, and the tip is immersed in the test water in the measurement tank. The microbial membrane holds iron-oxidizing bacteria (also called iron bacteria) that can convert ferrous sulfate to ferric sulfate using oxygen. The electrical output from the oxygen electrode is amplified and converted by the conversion calculation means, and a predetermined calculation is performed to determine the abnormal water quality of the test water.

  The chemical reaction formula of the chemical behavior by iron bacteria in the microbial membrane in contact with the test water in the measurement tank is as follows.

4FeSO ₄ + O ₂ + 2H ₂ SO ₄ → 2Fe ₂ (SO ₄ ) ₃ + 2H ₂ O (1)
In the above formula (1), 2Fe ₂ (SO ₄ ) ₃ is ionized in water to generate Fe ³⁺ ions. This Fe ³⁺ ion further reacts with water (H ₂ O) and precipitates as iron hydroxide Fe (OH) ₃ .

  In this abnormal water quality detection device, a mixed liquid of test water and iron liquid is fed to a dissolved oxygen electrode attached with iron-oxidizing bacteria as a probe, and the electrical output from the oxygen electrode at the time of feeding is monitored. . That is, when no harmful substance is mixed in the test water, the dissolved oxygen in the test water is consumed for iron oxidation, so the value detected by the oxygen electrode is extremely low. On the other hand, when a water-soluble harmful substance is mixed in the test water, the harmful substance reduces the respiratory activity of iron-oxidizing bacteria on the microbial membrane. As a result, oxygen that has not been consumed by the iron-oxidizing bacteria permeates the microbial membrane, so that the amount of oxygen that reaches the oxygen electrode increases and the current value output by the oxygen electrode increases. Therefore, the mixing of harmful substances is determined by comparing the output current value of the oxygen electrode with a threshold value.

  In addition, when such a biosensor type abnormal water quality detection apparatus is continuously operated, the pollutant in the test water adheres to and accumulates on the inner wall of each pipe. In addition, a part of ferrous sulfate in the iron solution is oxidized to ferric sulfate, which gradually accumulates. These lead to blockage of the piping system and a decrease in sensitivity of abnormal water quality detection, which causes a decrease in detection accuracy. Therefore, an acidic solution is supplied to the test water introduction pipe through which the mixture of the test water and the ferrous sulfate-containing solution is sent, and adheres to the test water passage such as the test water introduction pipe or the measurement tank. It removes accumulated pollutants and iron oxide and performs “acid cleaning” to discharge.

JP 2004-271441 A

  In such a biosensor-type abnormal water quality detection device, once an alarm of “water quality abnormality” is issued, an emergency system such as anti-terrorism measures is laid at a water purification plant, for example, and water intake is stopped or a temporary measure equivalent to it is taken. Be taken. However, if the “water quality abnormality” alarm becomes a false alarm, not only will the facility where the equipment is installed be greatly inconvenienced, but the operation of the facilities in the facility will be temporarily stopped due to the suspension of water intake. There will be no damage. Therefore, reliability for “water quality abnormality” warning is required.

  For this reason, the temperature control of the microbial film holding the iron bacteria in the sensor unit becomes severe. In other words, the water purification plant intake that is normally subject to water quality inspection by a biosensor is river surface water, and the water temperature in summer rises to 20-25 ° C, but falls to about 4 ° C in winter. Particularly in rivers in extremely cold regions, the surface of the river freezes and water is taken from the bottom of the ice, so it is not uncommon for the water temperature to cool to near freezing. If such a chilled sample water is supplied to a microbial membrane holding iron bacteria in the sensor section without heating anything, the activity of the iron bacteria is extremely reduced, and the behavior of oxygen consumption when contaminated with harmful substances Therefore, proper water quality monitoring is not possible.

  Therefore, in order to keep the sensor part and the measurement tank at 30 ° C. at all times, the cooled test water is first sufficiently passed through a flow cell having a heat exchange function provided so as to surround the measurement tank and heated to some extent. It will be supplied to the sensor unit later.

  However, as shown in FIG. 2, the amount of dissolved air generally increases as the temperature of water decreases. For this reason, when low-temperature water is heated rapidly, the air that appears without being dissolved becomes bubbles due to a decrease in the amount of saturated dissolved air, and adheres to the vicinity of the sensor unit and the measurement tank. When bubbles are generated in this way, the supply of nutrients for iron-oxidizing bacteria (ferrous sulfate) is inhibited, and in response, the reaction is the same as when iron bacteria are damaged by harmful substances and cannot be consumed. Show. For this reason, the device falsely recognizes “water quality abnormality” and issues an alarm.

  If there is only a problem of bubbles, as will be described later, if a heater is installed in the diffused water tank that is located upstream of the measurement tank and serves as a buffer tank, the bubbles will remain in the diffused water tank. This problem can be solved. However, since the test water is in a circulating state, flow rate fluctuations and the like are likely to occur, and it is extremely difficult to accurately heat the test water in this circulating state to a target temperature. In such a case, if the volume of the diffused water tank is increased to increase the heat capacity to the storage state, the test water can be accurately heated to the target temperature.

  Here, rapid detection of harmful substances is indispensable as a constraint condition of this apparatus. On the other hand, when the diffused water tank is enlarged, if harmful substances are mixed in the raw water, the raw water is diffused in the large volume diffused water tank, and the concentration of harmful substances is temporarily reduced. For this reason, it takes a considerable amount of time for the harmful substance concentrations in the raw water and the test water in the diffused water tank to be equal to each other, and it takes time to detect the harmful substances. Therefore, it is desirable that the volume of the diffused water tank that is a buffer tank is kept to a minimum, and therefore, it is necessary to heat in the running water upstream of the diffused water tank.

  An object of the present invention is to provide an abnormal water quality detection device and an abnormal water quality detection method capable of preventing a false alarm of “water quality abnormality” due to bubble generation, a low temperature state, or the like.

  The abnormal water quality detection device of the present invention is an abnormal water quality detection device that detects the presence or absence of an abnormality in the water quality while maintaining the test water in a preset temperature range, and is arranged around the introduction pipe of the test water. A water temperature adjusting device that is brought into contact with the temperature adjustment water controlled to a temperature close to the temperature range, and brings the temperature of the test water close to the temperature of the temperature adjustment water by heat transfer through the introduction pipe line, The water temperature adjusting device has a structure in which a predetermined length portion of the introduction pipe of the test water is installed in a tank in which the temperature adjusting water is stored, and is upstream of the water temperature adjusting device of the introduction pipe. On the side, a heater for heating the test water flowing through the introduction pipe line is provided.

  The abnormal water quality detection method of the present invention is an abnormal water quality detection method for detecting the presence or absence of an abnormality in the water quality in a state in which the test water is maintained in a preset temperature range, and the test water flowing through the introduction pipe line, The test water heated to a certain level or higher by a heater that is a first stage heater, and the test water heated to a certain level has a predetermined length portion of the test water introduction pipe line close to the temperature range. The temperature-adjusted water controlled by the temperature is passed through a water temperature adjusting device installed in a tank, and the periphery of the introduction water line of the test water is brought into contact with the temperature-adjusted water and transmitted through the introduction line. The temperature of the test water is brought close to the temperature of the temperature adjustment water by heat.

  According to the present invention, the water temperature is asymptotically approached to an appropriate temperature before entering the diffused water tank regardless of the temperature and flow rate of the inflowing test water, so that generation of bubbles in the measurement tank can be prevented, and Since the temperature of the water can be maintained within a predetermined range, the abnormal state of the test water can be accurately detected without being affected by foaming or a low temperature state.

1 is a system configuration diagram showing an embodiment of an abnormal water quality detection device according to the present invention. It is a characteristic view which shows the relationship between general water temperature and oxygen solubility.

  Hereinafter, embodiments of an abnormal water quality detection device according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows the overall configuration of an embodiment of the present invention. This abnormality detection device detects the presence or absence of an abnormality in the water quality while maintaining the test water in a preset temperature range, and as an example, a structure in which an oxygen electrode 10 is provided in the measurement tank 4 Are using things. A microbial membrane 9 is attached to the tip of the oxygen electrode 10 (the lower end in the figure in the measurement tank 4). Further, the measurement tank 4 is connected to the test water introduction pipe 2 and the test water is introduced. Further, the measuring tank 4 is adjusted to a predetermined temperature by a temperature adjuster 5 provided around the measuring tank 4. The temperature regulator 5 is connected to a circulating temperature regulator 24, and temperature-regulated water heated to a predetermined temperature is circulated and supplied.

  The microbial membrane 9 holds iron bacteria that can convert ferrous sulfate to ferric sulfate using oxygen. The oxygen electrode 10 is installed in a state where the tip end portion to which the microbial membrane 9 is attached is immersed in the test water in the measurement tank 4. Further, a conversion calculation means 11 is connected to the oxygen electrode 10, and the conversion calculation means 11 amplifies and converts the electrical output taken out from the oxygen electrode 10, performs a predetermined calculation, and is subjected to a process as described later. Determine abnormal water quality of sample water.

  As described above, the aeration water tank 7 also serves as a buffer for supplying the test water to the measurement tank 4, and the raw water of the water source to be inspected (for example, the inflow of the river or the inflow water to the water purification plant) Inflow water to a sewage treatment plant, etc.) is introduced through a filter 21 made of a hollow fiber membrane or the like, and is heated by a filtered water pump 18 and is connected to a pipe heater 22 and a water temperature adjusting device 23 on an introduction pipe line 17. Is introduced as test water.

  In the diffused water tank 7, air or a gas with a constant oxygen concentration is supplied from the gas supply device 8 to the introduced test water, and the test water is in a state where the dissolved oxygen concentration is saturated. The test water in which the dissolved oxygen concentration is saturated in this way is sent to the test water introduction pipe 2 by the test water supply pump 6 via the electromagnetic valve 20 and supplied to the measurement tank 4.

  An acidic solution pack 12 and an iron solution pack 13 communicate with the test water introduction tube 2 via corresponding electromagnetic valves 14 and 15, a common chemical solution introduction tube 19, and a chemical solution supply pump 16.

  The water temperature adjusting device 23 is brought into contact with the temperature adjusted water controlled to a temperature for keeping the measurement tank 4 in a predetermined temperature range by the circulating temperature controller 24 around the pipe line through which the test water flows. The temperature of the test water is brought close to the temperature of the temperature-adjusted water by heat transfer through a pipe line through which the test water flows. As the water temperature adjusting device 23, a coiled pipe having a high thermal efficiency is provided in a circulating hot water storage tank in the circulating temperature controller 24. That is, this coiled pipe is used as the water temperature adjusting device 23, and the detected water flowing in the coiled pipe is set to a target temperature of 30 ° C. by circulating hot water in the circulating hot water storage tank in the circulating temperature controller 24. Asymptotically.

  The circulation type temperature controller 24 has a heater (not shown), and is heated and controlled to maintain the temperature adjustment water stored therein at a predetermined temperature. The temperature adjustment water stored inside is circulated and supplied to the temperature adjuster 5 around the measurement tank 4 by the circulation path 24a.

  As the heater 22 provided on the upstream side of the water temperature adjusting device 23, a so-called pipe heater in which an electric heater is provided around the pipe line is used. As described above, it is extremely difficult to heat the test water in a circulating state to a target temperature accurately. Therefore, the heater 22 does not perform fine temperature control and the raw water temperature is below a certain level. Use it to turn it on and turn it off when it exceeds a certain temperature. For example, when the raw water (river water, etc.) becomes 10 ° C. or lower in winter, etc., raising the raw water temperature to the target value (for example, about 30 ° C.) using only the water temperature adjusting device 23 is a decrease in circulating temperature-controlled water. Resulting in problems such as difficulty in maintaining the temperature of the measuring tank 4. Therefore, the heater 22 is used as a first stage heater to heat the raw water temperature to a certain level or higher. Therefore, the heater 22 is not used in summer when the raw water temperature exceeds 20 ° C.

  As described above, the test water always has a saturated dissolved oxygen concentration in the diffused water tank 7 by the air supplied from the gas supplier 8 or the gas whose oxygen concentration is adjusted to be constant. Further, the acidic solution is supplied from the acidic solution pack 12, and the ferrous sulfate-containing solution is supplied from the iron solution pack 13, and mixed with the test water in the test water introduction pipe 2. This mixed liquid flows into the measurement tank 4 from the test water introduction pipe 2 in a state where the dissolved oxygen concentration is saturated as described above.

  The test water introduced into the measurement tank 4 must always have a saturated dissolved oxygen concentration to stabilize the maximum value of the output of the oxygen electrode 10. Since the saturated dissolved oxygen concentration varies depending on the liquid temperature, it is important to maintain the measurement tank 4 at a constant temperature by the temperature regulator 5 as described above.

Further, in the measurement tank 4, a microbial membrane 9 that holds iron bacteria that can convert ferrous sulfate to ferric sulfate using oxygen provided at the tip of the oxygen electrode 10, test water, The following reactions occur between: The iron bacteria held in the microbial membrane 9 is, for example, Thiobacillus ferrooxidans. The chemical reaction formula of this chemical behavior is as shown in the above formula (1), and 2Fe ₂ (SO ₄ ) ₃ is ionized in water to generate Fe ³⁺ ions. This Fe ³⁺ ion further reacts with water (H ₂ O) and precipitates as iron hydroxide Fe (OH) ₃ .

  In addition to the Thiobacillus ferrooxidans, all microorganisms having the function of the above chemical reaction formula can be applied as the iron bacteria held in the microbial membrane 9. For example, it has been confirmed that Gallionella ferruginea, Leptospirillum ferrooxidans, Leptothrix, Sphaerotilus and the like are suitable.

  Since the activity of iron bacteria, that is, the amount of oxidation of iron, may change due to the influence of temperature, the measuring tank 4 is maintained at a temperature at which the activity of iron bacteria is stabilized by the temperature regulator 5. Is desirable. The installation of the temperature regulator 5 is also important in this sense.

  As described above, the abnormal water quality detection device sends the mixed solution of the test water and the iron solution to the dissolved oxygen electrode 10 attached with the iron-oxidizing bacteria as a probe by the test water supply pump 6 and the chemical solution supply pump 16. The electric output from the oxygen electrode 10 at the time of liquid feeding is monitored. And when the water-soluble harmful | toxic substance in test water mixes, the harmful | toxic substance reduces the respiratory activity of the iron oxidation bacteria on the microbial membrane 9. FIG. As a result, oxygen that has not been consumed by the iron-oxidizing bacteria permeates through the microbial membrane 9, so that the amount of oxygen that reaches the oxygen electrode 10 increases. As a result, since the current value output from the oxygen electrode 10 increases, it is determined whether or not harmful substances are mixed.

  Next, the operation of the entire apparatus will be described. The abnormal water quality detection device mixes the test water obtained from the test water source as described above with the iron solution or the acidic solution and introduces it into the measurement tank 4. Drain. In the present invention, the test water obtained by filtering the raw water with the hollow fiber membrane filter 21 is first heated to about + 10 ° C. with the pipe heater 22. Next, the water temperature adjusting device 23 is brought into external contact with the circulating hot water stored in the circulating temperature controller 24, and asymptotically heated to a target temperature, for example, around 30 ° C.

  Usually, the temperature of river raw water used as test water varies between 0 to 25 ° C. according to the installation area, season, weather, and hourly temperature fluctuation. Here, if only the pipe heater 22 is heated, it is difficult to flexibly follow the water temperature fluctuation and to maintain and control the test water in a flowing state at around 30 ° C. at all times. That is, when the temperature condition of the influent water is set closer to a low temperature in the selection calculation of the output of the pipe heater 22, it tends to exceed 30 ° C. when the inflow condition is somewhat high, so the frequency of ON / OFF of the pipe heater 22 is high. As a result, the consumption of devices such as relay switches becomes severe. On the other hand, if the temperature condition of the influent water is set closer to the high temperature, frequent ON / OFF of the pipe heater 22 can be avoided throughout the year, but it is difficult to maintain and control the low-temperature test water at around 30 ° C.

  Furthermore, since the test water in the flowing water state is filtered water by the hollow fiber membrane filter 21, the flow rate of filtration changes depending on the state of the raw water turbidity, and therefore the condition of the flow rate of flow into the pipe heater 22 varies greatly. Since the heating efficiency improves as the flow rate decreases, it is difficult to maintain and control around 30 ° C. with the piping heater 22 alone. Further, the advanced piping heater 22 control greatly increases the cost of the apparatus and is difficult to adopt.

  Therefore, in the present embodiment, the water temperature adjusting device 23 is provided at the rear stage (downstream side) of the pipe heater 22. This water temperature adjusting device 23 is provided with a heat-efficient coiled pipe in the circulating hot water storage tank in the circulating temperature controller 24, and by the circulating hot water in the circulating hot water storage tank in the circulating temperature controller 24, The detected water flowing in the coiled pipe is made asymptotic to 30 ° C. which is the target temperature. Under the condition where the inflow temperature of the circulating hot water to the water temperature adjusting device 23 does not exceed 30 ° C., the temperature of the test water does not become 30 ° C. or higher even if it gradually approaches 30 ° C. When the temperature of the raw water serving as test water reaches 20 ° C. or more as in summer, it can be dealt with by always turning off the pipe heater 22.

  In the case of heating only the water temperature adjusting device 23, the capacity of the circulating temperature controller 24 needs to be increased in order to widen the temperature increase range. Therefore, as described above, it is advantageous in terms of equipment mounting space and cost to heat the pipe heater 22 in the previous stage to some extent (around 4 ° C. → 20 ° C.) and then gradually bring it closer to 30 ° C. with the water temperature adjusting device 23. It is.

  As described above, the microbial membrane 9 is held at the tip of the oxygen electrode 10, the amount of oxygen permeating through the microbial membrane 9 is measured with the dissolved oxygen electrode 10, and the biosensor-type abnormal water quality detection device 1 detects the contamination of harmful substances. Then, as a method of heating the test water, the pipe heater 22 is arranged in the front stage and the water temperature adjusting device 23 is arranged in the rear stage. Therefore, before the inflow to the aeration tank 7 regardless of the temperature and flow rate of the inflow of the test water. As a result, the water temperature is made asymptotic to an appropriate temperature to prevent the generation of bubbles in the measurement tank 4 and to prevent a false alarm of “water quality abnormality” resulting therefrom.

4 Measuring tank for detecting presence or absence of water quality 17 Test water introduction pipe 22 Heater 23 Water temperature adjustment device 24 Circulating temperature controller 24a Hot water circulation path

Claims (2)

An abnormal water quality detection device that detects the presence or absence of an abnormality in the water quality while maintaining the test water in a preset temperature range,
The periphery of the introduction pipe of the test water is brought into contact with temperature adjustment water controlled to a temperature close to the temperature range, and the temperature of the test water is adjusted by heat transfer through the introduction pipe. Equipped with a water temperature adjustment device that approaches the temperature,
The water temperature adjustment device is a structure in which a predetermined length portion of the test water introduction pipe is installed in a tank in which the temperature adjustment water is stored,
An abnormal water quality detection device, characterized in that a heater for heating the test water flowing through the introduction pipe is provided upstream of the water temperature adjustment device in the introduction pipe. An abnormal water quality detection method for detecting the presence or absence of an abnormality in the water quality while maintaining the test water in a preset temperature range,
The test water flowing through the introduction pipe is heated to a temperature above a certain level by a heater that is a first stage heater,
The temperature of the test water heated to a certain level is set in a tank that stores temperature-adjusted water in which a predetermined length of the introduction pipe of the test water is controlled to a temperature close to the temperature range. Poured into the adjusting device,
An abnormality characterized in that the periphery of the introduction pipe of the test water is brought into contact with the temperature adjustment water, and the temperature of the test water is brought close to the temperature adjustment water by heat transfer through the introduction pipe Water quality detection method.

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