JP2006349551A - Biosensor type abnormal water quality monitoring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and appropriately perform control of the substrate concentration of a substrate solution supplied for recovering the activity of microorganism within a biosensor. <P>SOLUTION: In a reaction tank 10, the microorganism held by a microorganism membrane 13 is reacted with mixed water, and a current signal according to the dissolved oxygen amount in the mixed water is outputted from a dissolved oxygen electrode 11 to a supply amount control means 28 through an output conversion part 27. The means 28 controls a valve 25 and a constant flow pump 26 according to input of the current signal, and transmits an activity adjusting substrate solution stored in an activity adjusting substrate solution storage container 23 to a supply line 7. According to this, the concentration of dipotassium hydrogenphosphate (K2HPO4) that is the activity adjusting substrate is appropriately controlled to stabilize the number of microorganism. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a biosensor-type abnormal water quality monitoring apparatus that utilizes biosensor technology that monitors the respiratory activity of microorganisms and detects the contamination of harmful substances in sample water using inhibition of respiratory activity as an index.

  Conventionally, a biosensor type water quality monitoring device using microorganisms has been used to detect harmful substances in the inflow of sewage water taken from a water purification plant. In this biosensor type abnormal water quality monitoring apparatus, microorganisms are immobilized on a membrane, and combined with an oxygen electrode, oxygen consumption due to respiration of microorganisms is monitored. When harmful substances are mixed, the respiration of microorganisms is inhibited and the oxygen consumption is reduced. Therefore, it is possible to detect the mixing of harmful substances by detecting the decrease in oxygen consumption at this time.

  The above-mentioned microorganisms usually live with a specific chemical substance (substrate) as a nutrient source. Also in a biosensor using microorganisms, a substrate component necessary for microorganisms is mixed with sample water and supplied to a reaction tank in which a microorganism film is present, thereby activating respiratory metabolism of microorganisms. Therefore, for example, an apparatus configuration as disclosed in Patent Document 1 is adopted. In the configuration of this conventional apparatus, a concentrated substrate solution containing a substrate component is stored in a storage container, the solution is fed by a pump and mixed with sample water, and the inside of a reaction vessel in which a microbial membrane is disposed By introducing into the microorganism, the substrate component is supplied to the microorganism.

  In addition, the present applicant has already proposed a configuration of an abnormal water quality monitoring apparatus including a biosensor using iron-oxidizing bacteria as a microorganism (see Patent Document 2). Iron-oxidizing bacteria are chemically synthesized autotrophic bacteria that live using the energy generated when ferrous ions participate in ferric ions. Therefore, the most important substrate component is ferrous ion (Fe2 +). The present applicant has put into practical use a biosensor-type abnormal water quality monitoring apparatus using Thiobacillus ferrooxidans (hereinafter referred to as T. ferrooxidans) as an iron-oxidizing bacterium. In this biosensor, a medium having the composition shown in the chart of FIG. 8 is used as a culture solution for microorganisms. This medium contains ferrous sulfate heptahydrate as a source of ferrous ions and other inorganic salts such as phosphate, calcium and magnesium necessary for the metabolism of microorganisms.

  FIG. 7 is an explanatory diagram showing a configuration of a conventional biosensor type abnormal water quality monitoring apparatus. In this figure, the sample water 3 supplied from the first sample water supply line 1 is stored in the diffused water tank 2, and air is blown into the sample water 3 so that the dissolved oxygen concentration is adjusted. . The sample water in which the dissolved oxygen concentration was adjusted was disposed in the flow cell 9 through the second sample water supply line 4 to which the valve 5 and the pump 6 were attached, and the sample water / substrate solution supply line 7. It is introduced into the biosensor 8.

  The biosensor 8 includes a reaction vessel 10 into which mixed water of sample water and substrate solution is introduced from the sample water / substrate solution supply line 7, and a current signal corresponding to the amount of oxygen contained in the mixed water in the reaction vessel 10. A dissolved oxygen electrode 11 and a microbial membrane 13 attached to one end of the dissolved oxygen electrode 11 via a fixing jig 12. And the sample water which finished the reaction with the microorganisms which the microbial membrane 13 hold | maintains in the reaction tank 10 is discharged | emitted outside through the drainage discharge line 14. FIG.

  Further, the substrate solution storage container 15 stores, for example, a substrate solution containing the substrate components shown in the chart of FIG. 8 and having the concentration and pH adjusted. The substrate solution passes through the substrate solution supply line 16 to which the valve 17 and the pump 18 are attached, and then merges with the sample water in the sample water / substrate solution supply line 7. Is supplied to the biosensor 8 for use as a nutrient solution. Thus, the substrate solution is supplied from the substrate solution storage container 15 to the biosensor 8 for the following reason.

  That is, since microorganisms cannot grow in the absence of a substrate, the microorganisms in the microorganism membrane gradually die out as they are. In addition, when the substrate concentration is lower than a certain concentration, the number of microorganisms that die is greater than the number of microorganisms that grow. Therefore, the number of microorganisms in the microorganism membrane gradually decreases, and the biosensor 8 The stability as a sensor function is impaired. Therefore, in order to maintain the function of the biosensor 8 utilizing microorganisms in a good state, it is necessary to supply the substrate components necessary for the growth of the microorganisms used to the microorganism membrane more than a certain necessary amount. . For this reason, the substrate solution is supplied from the substrate solution storage container 15 to the biosensor 8.

  A cleaning liquid storage container 19 in which the cleaning liquid is stored is also installed. This cleaning liquid passes through the cleaning liquid delivery line 20 to which the valve 21 and the pump 22 are attached, and the sample water / substrate solution supply line 7. 8 is sent out.

  Next, the operation of FIG. 7 will be described. When starting the water quality monitoring of the sample water, the operator first opens the valve 5 and activates the pump 6. As a result, the sample water 3 stored in the diffused water tank 2 is supplied to the biosensor 8 via the second sample water supply line 4 and the sample water / substrate solution supply line 7. And in the reaction tank 10, the microbe hold | maintained at the microbe film | membrane 13 and sample water react, and the presence or absence of water quality abnormality is discriminate | determined based on the reaction state. That is, when there is no abnormality in the water quality of the sample water, the activity of the microorganisms held in the microbial membrane 13 is not inhibited, so the dissolved oxygen in the sample water is consumed as usual, and the level of the current signal detected from the dissolved oxygen electrode 11 Is a low level (this current signal is converted by an output conversion unit (not shown) and then displayed on the display unit). However, when a harmful substance is contained in the sample water, the consumption of dissolved oxygen is reduced because the activity of microorganisms is inhibited, and the current signal is at a high level. Therefore, the operator can know that the water quality is abnormal due to the fluctuation of the level of the current signal.

  The microorganisms retained on the microbial membrane 13 lose their overall activity gradually as the number of individuals decreases while continuing the reaction with the sample water as described above, and the stability as a sensor function is increased. It will be damaged. Therefore, the operator opens the valve 17 and activates the pump 18 to transfer the substrate solution stored in the substrate solution storage container 15 through the substrate solution supply line 16 and the sample water / substrate solution supply line 7 to the biosensor 8. As appropriate. Thereby, the activity of the microorganisms held in the microorganism film 13 returns to the original level again, and the stability as the sensor function is restored.

  FIG. 9 is a characteristic diagram showing an example of the supply of the substrate solution as described above and the level fluctuation of the current signal. In this figure, the activity of microorganisms was initially reduced, and the current value had increased to around 1.0 [μA], but at a certain time (around 7 minutes), the operator had a substrate solution containing ferrous sulfate. Is supplied, the microorganisms are rapidly activated and the current value is reduced to a level around 0.1 [μA]. After that, the stable state was maintained at this level for a while. However, if a harmful substance is added to the sample water at about 15 minutes, the current value gradually increases because the activity of the microorganisms is thereby reduced. Then, when an abnormal setting level is exceeded (at about 21 minutes), an abnormal alarm is issued, an abnormal display, or the like is performed.

While the water quality monitoring operation as described above continues for a certain period of time, dirt and impurities in the sample water / substrate solution supply line 7 and the drainage discharge line 14 accumulate, and if this is left as it is, Smooth water quality monitoring operation cannot be performed. Therefore, the operator stops the pumps 6 and 18 and closes the valves 5 and 17 at predetermined intervals, and then opens the valve 21 and starts the pump 22. As a result, the cleaning liquid stored in the cleaning liquid storage container 19 is sent from the cleaning liquid delivery line 20 to the other lines, and cleaning is performed to remove dirt, impurities, and the like.
JP 2002-243698 A Japanese Patent Laid-Open No. 11-37969

  As described above, the operator monitors the detected current of the dissolved oxygen electrode 11 and supplies the substrate solution from the substrate solution storage container 15 to the biosensor 8 when it is determined that the activity of the microorganism is reduced. By doing so, the activity of the microorganism can be recovered. However, it is not always easy to appropriately control the supply amount of the substrate solution.

  In other words, in order to reliably stabilize the operation of the biosensor, it is sufficient to add an excessive amount of substrate. However, if the substrate is included excessively more than necessary, the growth of microorganisms will proceed excessively and harmful substances will not be generated. Only some microorganisms will inhibit respiration when mixed. And since oxygen is consumed by the respiration of the remaining microorganisms to the same extent as before, changes in oxygen consumption are less likely to appear. As a result, the detection sensitivity for harmful substances is lowered, and it is difficult to detect the mixing of low-concentration harmful substances.

  FIG. 10 is an explanatory diagram showing that the detection sensitivity of a biosensor is greatly influenced by the number of microorganisms. (A) shows characteristic curves M1 to M4 in which the combinations of the number of microorganisms and the concentration of harmful substances (KCN) are different. The characteristic diagram shown, (b) is a chart showing the number of each microorganism and the numerical value of the harmful substance concentration in the characteristic curves M1 to M4.

  As is apparent from the numerical values in FIG. 10B, the characteristic M1 has a small number of microorganisms ("less" means less than M3 and M4, and may be rephrased as "appropriate number"). When the concentration of harmful substances is high, the characteristic M2 has a small number of microorganisms and the concentration of harmful substances is low, the characteristic M3 has a large number of microorganisms and the concentration of harmful substances is high, the characteristic M4 has a large number of microorganisms and the concentration of harmful substances Each case is low.

  FIG. 10 (a) shows the change state of the detected current value of the biosensor when KCN (potassium cyanide), which is a harmful substance, is added to the sample water at around 20 seconds, and the characteristic curve M1. As shown by M2, when the number of microorganisms is small, the detection sensitivity is sufficient whether the concentration of harmful substances is high or low. On the other hand, as shown by the characteristic curves M3 and M4, when the number of microorganisms is large, the detection sensitivity is insufficient when the concentration of harmful substances is high or low. From this result, it can be seen that the number of microorganisms in the microbial membrane is a factor that greatly affects the responsiveness when a harmful substance is added.

  In order to avoid the phenomenon that the detection sensitivity to harmful substances as described above is lowered, it is necessary to maintain the activity of the entire microbial membrane 13 at a certain level, and the substrate concentration in the nutrient solution is set appropriately. There is a need to. For this reason, it is sufficient to supply a substrate having a concentration sufficient to activate respiration of the microbial membrane 13 on which a certain number of microorganisms are immobilized. There is a case. In such a case as well, when the excessive substrate is added, the microorganisms are in an overproliferated state, and there is a possibility that the detection sensitivity of harmful substances is lowered.

  Conversely, if the substrate concentration is low, the sample water pH will change, the influence of raw water quality such as the inclusion of trace respiration inhibiting components other than harmful substances, other under-nutrition conditions in the washing process, fluctuations in the amount of nutrient solution delivered, etc. Microorganisms may be gradually killed due to device effects. In such a case, the number of microbial individuals in the microbial membrane gradually decreases, so that sufficient activity for operating the biosensor cannot be obtained, and stable operation becomes difficult.

  Therefore, it is conceivable to set the substrate concentration at a high concentration in advance and make it continuously operable for a long period of time. However, if such a measure is taken, the long-term stable storage and stable supply of nutrient solution can be considered. May be disadvantageous. This is because, since microorganisms usually require multiple types of chemical substances for growth, the substrate component contains multiple types of chemical substances, but when multiple types of chemical substances exist, A chemical reaction occurs, and a phenomenon such as generation of a precipitate occurs. Due to this deposit, there is a possibility that clogging or the like may occur in the pipe through which the mixed water of the sample water and the substrate solution flows, and stable liquid feeding cannot be performed. This chemical reaction is more likely to occur as the substrate concentration becomes higher.

  The present invention has been made in view of the above circumstances, and biosensor type abnormal water quality monitoring that can easily and appropriately control the substrate concentration of a substrate solution supplied to recover the activity of microorganisms in the biosensor. The object is to provide a device.

  As a means for solving the above-mentioned problems, the invention described in claim 1 introduces a mixed water of a substrate solution containing a plurality of substrate components serving as nutrient sources for microorganisms and sample water, and is contained in this mixed water. A biosensor having a microbial membrane holding the microorganisms that consume dissolved oxygen and a dissolved oxygen electrode that outputs a current signal according to the amount of consumption of the dissolved oxygen, and the current signal exceeds an abnormal setting level In the biosensor type abnormal water quality monitoring apparatus for determining that the water quality is abnormal in some cases, a substrate component for activity adjustment for activating the microorganism is stored, including a substrate component not involved in respiratory metabolism of the microorganism Based on the substrate solution storage container for activity adjustment and the output of the current signal, when it is determined that the consumption of the dissolved oxygen has decreased below a certain level and the activity of the microorganism has decreased Characterized in that the reservoir activity adjusting substrate solution and an active adjustment substrate solution supplying means for supplying to said biosensor.

  The invention according to claim 2 is the invention according to claim 1, wherein the substrate solution supply means for activity adjustment is a constant flow pump, and the operation time of the constant flow pump is set according to the degree of decrease in the activity of the microorganism. It is variable.

  According to a third aspect of the present invention, in the first aspect of the invention, the activity adjusting substrate solution supply means is a variable flow rate pump, and the flow rate of the variable flow rate pump is variable depending on the degree of decrease in the activity of the microorganism. It is characterized by.

  According to a fourth aspect of the present invention, in the substrate solution storage container for activity adjustment, the first activity adjustment substrate solution in which a concentration of a substrate component not involved in respiratory metabolism of the microorganism is a normal concentration is stored. An activity adjusting substrate solution storage container, a second activity adjusting substrate solution storage container storing a second activity adjusting substrate solution having a low concentration of a substrate component not involved in respiratory metabolism of the microorganism, and The activity adjusting substrate solution supply means supplies the stored second activity adjusting substrate solution to the biosensor when the degree of decrease in the activity of the microorganism is small, When the degree of activity decrease of the microorganism is normal or significant, the stored first activity adjusting substrate solution is supplied to the biosensor.

  The invention according to claim 5 is characterized in that, in the invention according to claims 1 to 4, the microorganism is an iron-oxidizing bacterium, and the substrate component not involved in respiratory metabolism of the microorganism is dipotassium hydrogen phosphate. To do.

  The invention according to claim 6 is directed to a cleaning liquid storage container storing a cleaning liquid for cleaning the supply line of the mixed water and the substrate solution for activity adjustment, and the cleaning liquid stored at the time of cleaning toward the supply line. Cleaning liquid delivery means for delivery.

  As described above, according to the present invention, a substrate solution storage container for activity adjustment containing a substrate component not involved in respiratory metabolism of microorganisms and storing a substrate solution for activity adjustment for activating microorganisms, and a current signal Based on the output of, the activity adjustment substrate that supplies the stored activity adjustment substrate solution to the biosensor when it is determined that the consumption of dissolved oxygen has fallen below a certain level and the activity of the microorganism has decreased. And a solution supply means, so that the biosensor type abnormal water quality monitoring device can easily and appropriately control the substrate concentration of the substrate solution supplied to recover the activity of microorganisms in the biosensor. Can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the same components as those of the conventional apparatus in FIG.

  FIG. 1 is an explanatory diagram showing the configuration of the biosensor type abnormal water quality monitoring apparatus according to the first embodiment of the present invention. FIG. 1 differs from FIG. 7 in that an activity adjusting substrate solution storage container 23 is added, and the activity adjusting substrate solution stored in the container is supplied with a valve 25 and a pump 26 (activity adjusting substrate solution supplying means). The sample water / substrate solution supply line 7 is sent through an activity adjusting substrate solution supply line 24 to which a constant flow pump is attached. The current signal detected from the dissolved oxygen electrode 11 is output to the supply amount control means 28 via the output conversion unit 27, and the supply amount control means 28 controls the valve 25 and the pump 26.

  Here, the reason why the substrate solution storage container 15 in addition to the substrate solution storage container 15 is added separately as described above will be described. As described above, in order to avoid the phenomenon that the detection sensitivity to harmful substances decreases, it is necessary to maintain the activity of the entire microbial membrane 13 at a certain level, and the substrate concentration in the nutrient solution is set appropriately. There is a need to.

  That is, when the water quality condition of the sample water is in an environment where the microorganisms in the biosensor are likely to grow, the concentration in the reaction tank with the microorganisms is reduced by a method such as limiting the amount of substrate supplied. As a result, excessive proliferation of microorganisms can be suppressed, and a decrease in detection sensitivity for harmful substances can be prevented. Conversely, when the water quality condition of the sample water is an environment that is unsuitable for the microorganisms of the biosensor, the concentration in the reaction tank with the microorganisms is increased by a method such as increasing the amount of substrate supplied. As a result, it is possible to improve the activity of microorganisms, which is effective for stabilizing biosensor output.

  The substrate component contains chemical substances that do not directly affect the respiratory activity of microorganisms. In order for the microorganisms to grow, it is necessary to supply all the substrates, and it is possible to adjust the supply amount of the substrate components for all the components. On the other hand, an effective strategy for improving the biosensor activity immediately is to always supply only the components necessary for respiratory metabolism. For example, the substrate component in the case of using the iron-oxidizing bacterium T. ferrooxidans as a biosensor microorganism is shown in the chart of FIG. 8, but the substrate component necessary for obtaining the substrate component respiratory activity is ferrous sulfate. It is. Other components are necessary to maintain long-term respiratory activity, but only ferrous sulfate that can activate respiratory metabolism may be added to monitor the contamination of harmful substances.

  However, if the concentration of the substrate component that activates respiratory metabolism varies greatly, the output of the biosensor becomes unstable this time, making it difficult to monitor stable water quality. Therefore, by selecting a component that does not participate in respiratory metabolism as a substrate component for adjusting the supply amount and adjusting the supply amount of the component, the concentration of the component in the reaction tank with the microorganism is adjusted. To. By this method, it is possible to obtain a stable respiratory activity at all times, control the growth tendency of microorganisms, and effectively maintain the performance and stable operation of the biosensor.

  In the present embodiment, dipotassium hydrogen phosphate described in the chart of FIG. 8 is selected and used as the component not involved in the respiratory metabolism, and this dipotassium hydrogen phosphate is used as a substrate solution for activity adjustment. As shown in FIG. 4, the activity adjustment substrate solution storage container 23 is stored. Then, the supply amount of dipotassium hydrogen phosphate to the biosensor 8 is controlled, and the concentration of dipotassium hydrogen phosphate that reacts with microorganisms, that is, iron-oxidizing bacteria T. ferrooxidans, in the reaction tank 10 is adjusted. This makes it possible to always obtain sufficient activity for the iron-oxidizing bacterium T. ferrooxidans, and to suppress long-term fluctuations in the number of individuals.

  By the way, the phosphate ion (PO43-) contained in dipotassium hydrogen phosphate and the ferrous ion (Fe2 +) contained in ferrous sulfate easily bind to each other to form iron phosphate that is hardly soluble in water. To do. In this case, it is possible to set the iron phosphate so as to be in a dissolved state by adjusting the pH, but there is a possibility that precipitation may occur little by little in the piping or the like due to an increase in temperature or the like. In that case, there are concerns about adverse effects such as valve blockage, sealing failure, pumping failure, etc. due to the deposits. However, if phosphate ions and ferrous ions are stored separately and supplied through separate lines, the generation of precipitates can be reduced, and liquid feeding should be performed stably. Can do. Therefore, in the present embodiment, as described above, the substrate solution storage container for activity adjustment 23 in which dipotassium hydrogen phosphate is stored is separately added to the substrate solution storage container 15.

  Next, the substrate solution stored in the substrate solution storage container 15 in the present embodiment will be described. The inventors of the present invention are conducting an experiment to determine the substrate components of the substrate solution stored in the substrate solution storage container 15 and will be described.

  FIG. 2 is a chart that describes the components of the three types of substrate solutions A, B, and C used in this experiment. The substrate solution A is the same component as the medium composition shown in the diagram of FIG. 8, and the substrate solution B is obtained by removing only dipotassium hydrogen phosphate (K2HPO4) from the components of the substrate solution A. In the solution C, the weight of this dipotassium hydrogen phosphate (K2HPO4) is one tenth of that of the substrate solution A. And the weight of components other than dipotassium hydrogen phosphate is the same in any of the substrate solutions A, B, and C. In addition, the pH value when activating the iron-oxidizing bacteria T. ferrooxidans by supplying ferrous ions (Fe2 +) contained in ferrous sulfate, as shown in the chart of FIG. A value of 3 or a value around it is preferred.

  FIG. 3 is a characteristic diagram showing a change state of the current value of the biosensor 8 when the three types of substrate solutions A, B, and C shown in the chart of FIG. 2 are continuously operated. . Here, three types of mixed water obtained by mixing 4 [ml] of each substrate solution with 100 [ml] of sample water is supplied to the reaction tank 10. During the period from time t1 to t2 and during the period from time t3 to t4, cleaning is performed by sending a cleaning solution such as sulfuric acid. During this period, iron ions are not supplied, so the current value increases in a rectangular shape. In addition, the activity of the iron-oxidizing bacterium T. ferrooxidans, which is a microorganism, has been significantly reduced.

  Since the concentrations of iron ions contained in all of the substrate solutions A, B, and C are the same, the activity of the microorganisms is approximately the same at an early stage before time t1. Then, the activity of the microorganisms is greatly reduced during the first washing period from time t1 to t2, and since the iron ions are supplied again after time t2 after the washing is finished, the activity of the microorganisms is recovered. The level of activity at the time of recovery in this case is the lowest in the substrate solution B from which dipotassium hydrogen phosphate has been removed (the highest current value level), and the substrate solution A containing the most dipotassium hydrogen phosphate. The substrate solution C, which is the highest and the amount of dipotassium hydrogen phosphate is 1/10 of the substrate solution A, is at an intermediate level between A and B. However, it can be said that the substrate solution A is in a state where the current level tends to decrease between the times t2 and t3 and the activity level of the microorganisms is not somewhat constant.

  When the second cleaning is performed during the period from time t3 to t4, the activity of the microorganism is greatly reduced as in the previous cleaning, and the activity of the microorganism is recovered after time t4 when the supply of iron ions is started. To do. In this case, the level at the time of recovery after time t4 is almost the same as the level at time t3 for the substrate solutions A and C, but the substrate solution B is damaged from the microorganisms by washing, so that the level is higher than the level at time t3. Has also increased. Such damage to the microorganisms due to the cleaning is repeated for each cleaning operation, and in the case of the substrate solution B, the number of microorganisms gradually decreases.

  Therefore, it can be said that the substrate solution B is unsuitable as the substrate solution stored in the substrate solution storage container 15. The substrate solution A is substantially constant while the activity of the microorganisms is not constant during the period from time t2 to time t3. From these facts, it can be said that the substrate solution C is optimal, and in this embodiment, the substrate solution C is stored in the substrate solution storage container 15.

  In order to control the growth tendency of the iron-oxidizing bacterium T. ferrooxidans, which is a microorganism, from the changes in the current values of the substrate solutions A, B, and C shown in FIG. It can be seen that the concentration of dipotassium hydrogen phosphate may be adjusted. That is, when the activity of the microbial membrane 13 becomes excessive, the concentration of dipotassium hydrogen phosphate is reduced to suppress the growth of the microorganism, and conversely, when the activity of the microbial membrane 13 deteriorates, the hydrogen phosphate is reduced. If the growth of microorganisms is promoted by increasing the concentration of 2 potassium, the number of microorganisms in the microorganism film 13 can be maintained at a constant level. This is the reason why dipotassium hydrogen phosphate was selected as the substrate solution for activity adjustment stored in the substrate solution storage container 23 for activity adjustment.

  Next, the operation of FIG. 1 configured as described above will be described. The operator opens the valve 5 to start the pump 6 and opens the valve 17 to start the pump 18. Thereby, the mixed water of the sample water 3 stored in the diffused water tank 2 and the substrate solution stored in the substrate solution storage container 15 (substrate solution C in the diagram of FIG. 2) is the sample water / substrate solution. It is supplied to the biosensor 8 via the supply line 7.

  Then, in the reaction tank 10, the microorganisms held in the microbial membrane 13 react with the mixed water, and a current signal corresponding to the dissolved oxygen amount in the mixed water is supplied from the dissolved oxygen electrode 11 through the output conversion unit 27 to control the supply amount. It is output to the means 28. The supply amount control means 28 controls the valve 25 and the constant flow pump 26 based on the input of this current signal, and supplies the substrate solution for activity adjustment stored in the substrate solution storage container 23 for activity adjustment to the sample water / substrate solution supply. Send to line 7 As a result, the concentration of dipotassium hydrogen phosphate (K2HPO4), which is an activity adjusting substrate, is appropriately controlled, and the number of microorganisms held by the microorganism membrane 13 can be stabilized.

  4A and 4B are explanatory diagrams for controlling the concentration of the activity adjusting substrate at this time. FIG. 4A is a characteristic diagram of the current value change of the biosensor 8, and FIG. 4B is an activity adjusting substrate from the storage container 23. (C) is a characteristic diagram regarding the concentration change of the substrate for activity adjustment.

  Initially, as shown in FIG. 4A, the detected current value from the dissolved oxygen electrode 11 is just over the target current value. Therefore, it is not necessary to increase the amount of the activity adjusting substrate solution delivered from the activity adjusting substrate solution storage container 23 to the sample water / substrate solution supply line 7. Therefore, as shown in FIG. 4 (b), the supply amount control means 28 supplies the substrate solution for adjusting the activity only for a short time at intermittent timings at times t1, t2, t3, and t4. At this time, the concentration of the substrate for activity adjustment in the mixed water does not become so high as shown in FIG.

  Thereafter, as shown in FIG. 4A, the detected current value is lower than the target current value. In this state, it is not necessary to supply the activity adjusting substrate solution from the activity adjusting substrate solution storage container 23. . Therefore, as shown in FIG. 4B, after the last supply is performed at time t4, the supply is not performed for a while. And in the period when this supply is not performed, naturally the density | concentration of the substrate for activity adjustment in FIG.4 (c) becomes substantially zero.

  After a while, the detected current value in FIG. 4 (a) again exceeds the target current value, and the supply amount control means 28 resumes the short-time supply of the substrate solution for activity adjustment at time t5, and time t6. A slightly longer supply. However, since the level of the detected current value continues to rise, the supply amount control means 28 performs continuous supply over a long period of time t7 to t8. As a result, as shown in FIG. 4A, the rising tendency of the detected current value is stopped, and this time, it gradually falls. Accordingly, the supply amount control means 28 performs the supply for a time not so long at time t9 after stopping the continuous supply at time t8. The concentration of the activity adjusting substrate at this time is at a high level as shown in FIG.

  As described above, in the configuration of FIG. 1, since the substrate solution storage container 23 for activity adjustment is provided separately from the substrate solution storage container 15, the number of microorganisms of the microorganism membrane 13 can be easily maintained at a certain level. Can do. That is, in the conventional configuration of FIG. 7, the number of microorganisms is adjusted by controlling the supply amount of the substrate solution from the substrate solution storage container 15, but in this case, sulfuric acid that directly activates respiratory metabolism of microorganisms. Since the amount of ferrous iron varies greatly, the detection sensitivity of the biosensor 8 becomes unstable. On the other hand, in the configuration of FIG. 1, the supply amount of the substrate solution from the substrate solution storage container 15 is constant, and the supply amount of the substrate solution for activity adjustment containing the substrate component not involved in the respiratory metabolism of the microorganism is controlled. Therefore, it becomes easy to make the number of microorganisms of the microorganism film 13 constant. And since this substrate solution for activity adjustment is stored in the substrate solution storage container 23 for activity adjustment separately from the solution of the substrate solution storage container 15, generation | occurrence | production of a precipitate etc. is reduced and stable liquid feeding is performed. be able to.

  FIG. 5 is an explanatory diagram showing a configuration of a biosensor type abnormal water quality monitoring apparatus according to the second embodiment of the present invention. FIG. 5 differs from FIG. 1 in that the constant flow pump 26 as the substrate solution supply means for activity adjustment is replaced with a variable flow pump 26A. That is, in the configuration of FIG. 1, the concentration of dipotassium hydrogen phosphate is appropriately controlled by changing the length of time for supplying the substrate solution for activity adjustment by the constant flow pump 26. Then, the concentration of dipotassium hydrogen phosphate is appropriately controlled by changing the rotation speed of the flow rate variable pump 26A, that is, the flow rate. Therefore, according to this embodiment, it is possible to adjust the number of microorganisms held by the microorganism film 13 more quickly and appropriately.

  FIG. 6 is an explanatory diagram showing the configuration of the biosensor type abnormal water quality monitoring apparatus according to the third embodiment of the present invention. FIG. 6 is different from FIG. 1 in that a second activity adjusting substrate solution storage container 29 is added, and the activity adjusting substrate solution stored in this is attached with a valve 31 and a pump 32 (constant flow pump). The second activity adjusting substrate solution supply line 30 is sent to the sample water / substrate solution supply line 7. The constituent elements 23 and 24 are the same as those in FIG. 1 or FIG. 5, but in order to make the distinction from the elements 29 and 30 easy to understand, the expression “first ...” is used. ing. The second activity adjustment substrate solution stored in the second activity adjustment substrate solution storage container 29 is the first activity adjustment substrate stored in the first activity adjustment substrate solution storage container 23. The concentration is lower than that of the solution.

  The supply amount control means 28 controls the valves 25 and 31 and the pumps 26 and 32 based on the current signal input from the dissolved oxygen electrode 11 via the output conversion unit 27, and when the degree of decrease in the activity of the microorganism is small A second activity adjusting substrate solution having a low concentration is supplied to the biosensor 8 from the second activity adjusting substrate solution storage container 29. On the other hand, when the degree of decrease in the activity of microorganisms is normal or significant, the first is used. A first activity adjusting substrate solution is supplied from the activity adjusting substrate solution storage container 23 to the biosensor 8. Therefore, according to this embodiment, the number of microorganisms held by the microorganism film 13 can be adjusted more finely and accurately.

Explanatory drawing which shows the structure of the biosensor type abnormal water quality monitoring apparatus which concerns on the 1st Embodiment of this invention. The chart which described each component of three types of substrate solutions A, B, and C used for the experiment for determining the substrate component of the substrate solution stored in the substrate solution storage container 15 in FIG. The characteristic view which showed the change state of the electric current value of the biosensor 8 at the time of drive | operating continuously using three types of substrate solution A, B, C shown by the chart of FIG. FIG. 7 is an explanatory diagram for controlling the concentration of the substrate for activity adjustment when the substrate solution for activity adjustment is supplied from the substrate solution storage container for activity adjustment in FIG. 1, and FIG. FIG. 5B is a time chart showing the timing of supplying the activity adjusting substrate from the storage container 23, and FIG. 5C is a characteristic diagram regarding the concentration change of the activity adjusting substrate. Explanatory drawing which shows the structure of the biosensor type abnormal water quality monitoring apparatus which concerns on the 2nd Embodiment of this invention. Explanatory drawing which shows the structure of the biosensor type abnormal water quality monitoring apparatus which concerns on the 3rd Embodiment of this invention. Explanatory drawing which shows the structure of the conventional biosensor type | mold abnormal water quality monitoring apparatus. The chart which shows the composition of the culture medium which the biosensor 8 in FIG. 7 uses as a culture solution of microorganisms. The characteristic view which shows an example of the level fluctuation | variation of the electric current signal of the biosensor 8 in FIG. It is explanatory drawing which shows that the detection sensitivity of the biosensor 8 in FIG. 7 is greatly influenced by the number of microorganisms, (a) shows characteristic curves M1 to M4 in which the combinations of the number of microorganisms and the harmful substance (KCN) concentration are different. The characteristic diagram shown, (b) is a chart showing the number of each microorganism and the numerical value of the harmful substance concentration in the characteristic curves M1 to M4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st sample water supply line 2 Aeration water tank 3 Sample water 4 2nd sample water supply line 5 Valve 6 Pump 7 Sample water and substrate solution supply line 8 Biosensor 9 Flow cell 10 Reaction tank 11 Dissolved oxygen electrode 12 Fixed treatment Tool 13 Microbial membrane 14 Drainage discharge line 15 Substrate solution storage container 16 Substrate solution supply line 17 Valve 18 Pump 19 Cleaning solution storage container 20 Cleaning solution delivery line 21 Valve 22 Pump 23 Substrate solution storage container 24 for activity adjustment Supply substrate solution for activity adjustment Line 25 Valve 26 Constant flow pump 26A Flow variable pump 27 Output converter 28 Supply amount control means 29 Second substrate substrate for storage of activity adjustment 30 Second substrate substrate supply line for activity adjustment 31 Valve 32 Pumps M1 to M4 Characteristics curve

Claims (6)

Introducing a mixed water of a substrate solution containing a plurality of substrate components serving as a nutrient source of microorganisms and sample water, and holding a microorganism film that consumes the dissolved oxygen contained in the mixed water, and a membrane of the dissolved oxygen A biosensor-type abnormal water quality monitoring device that includes a biosensor having a dissolved oxygen electrode that outputs a current signal according to consumption and determines that the water quality is abnormal when the current signal exceeds an abnormal setting level In
A substrate solution storage container for activity adjustment containing a substrate component not involved in respiratory metabolism of the microorganism, and storing a substrate solution for activity adjustment for activating the microorganism;
Based on the output of the current signal, when it is determined that the consumption of the dissolved oxygen has decreased below a certain level and the activity of the microorganism has decreased, the stored substrate for adjusting the activity is supplied to the biosensor. Substrate solution supply means for activity adjustment to be supplied
A biosensor type abnormal water quality monitoring device characterized by comprising: The activity adjusting substrate solution supply means is a constant flow pump, and the operation time of the constant flow pump is varied according to the degree of decrease in the activity of the microorganism.
The biosensor type abnormal water quality monitoring device according to claim 1. The activity adjusting substrate solution supply means is a flow rate variable pump, and the flow rate of the flow rate variable pump is varied in accordance with the degree of decrease in the activity of the microorganism.
The biosensor type abnormal water quality monitoring device according to claim 1. The activity adjustment substrate solution storage container includes a first activity adjustment substrate solution storage container in which a first activity adjustment substrate solution having a normal concentration of a substrate component not involved in respiratory metabolism of the microorganism is stored. , A second activity adjusting substrate solution storage container storing a second activity adjusting substrate solution having a low concentration of the substrate component not involved in the respiratory metabolism of the microorganism, and
The activity adjusting substrate solution supplying means supplies the stored second activity adjusting substrate solution to the biosensor when the degree of decrease in the activity of the microorganism is small. When the degree is normal or significant, the stored first activity adjusting substrate solution is supplied to the biosensor.
The biosensor type abnormal water quality monitoring device according to claim 1. The microorganism is an iron-oxidizing bacterium, and the substrate component not involved in the respiratory metabolism of the microorganism is dipotassium hydrogen phosphate,
The biosensor type abnormal water quality monitoring apparatus according to claim 1, wherein: A cleaning liquid storage container storing a cleaning liquid for cleaning the supply line of the mixed water and the activity adjusting substrate solution;
Cleaning liquid delivery means for delivering the stored cleaning liquid toward the supply line during cleaning;
The biosensor type abnormal water quality monitoring device according to claim 1, wherein the abnormal water quality monitoring device is provided.

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