JP4720134B2 - Water disinfection device and disinfection method - Google Patents

Description

  The present invention relates to sterilization or disinfection technology for water in general, and, for example, to a disinfection method and disinfection apparatus for disinfecting or disinfecting water to be treated or secondary treated water of sewage or sewage.

  In general, after removing ammonia nitrogen, iron, etc. from raw water collected from rivers, etc. in water treatment plants, clean water is sterilized by disinfecting microorganisms in the water after removing suspended substances by agglomeration and rapid filtration. It has been processed. On the other hand, sewage is treated at the sewage treatment plant to remove organic substances and suspended solids (SS) by the activated sludge method, and then sludge is separated, disinfected and sterilized before being put into rivers, etc. Released.

  The standard value of treated water quality after disinfection and sterilization is determined such that the number of E. coli is not detected and the number of general bacteria is 100 / mL in clean water. On the other hand, the standard in the discharged water of the sewer is set so that the number of coliforms is 3000 or less.

  The culture method is usually used to measure the number of microorganisms such as E. coli, general bacteria, and coliforms. For example, the number of coliforms in sewage is generally measured by the desoxycholate agar medium method.

  In this method, a sample to be measured or a diluted solution of the sample to be measured is mixed in a desoxycholate agar medium so that the microorganisms are uniformly dispersed, and the microorganisms are cultured on a nutrient-containing medium. In this method, each microorganism (cell) is grown to a colony having a distinguishable size, the number of colonies is counted, and the number of microorganisms is obtained from the number of colonies. In such a culture method, since culture of microorganisms is used, generally 18 hours or more are required for measurement, and it is difficult to say that it is a rapid measurement means.

  Therefore, the injection rate of the disinfectant for disinfecting microorganisms in water is not based on the measured value of the number of coliforms by this culture method, but empirically considering the amount of treated water, ammonia concentration, organic matter concentration, etc. Has been decided. In determining the injection rate based on such experience, the amount of the disinfectant tends to be excessive or insufficient.

On the other hand, several disinfection systems that properly inject a disinfectant without excess or deficiency have been proposed so far.
For example, in disinfection of sewage, control of making the residual chlorine concentration constant by determining the chlorine injection rate after measuring the inflow of treated water and the residual chlorine concentration of the disinfectant after disinfection and performing feedback control. (See Patent Document 1).

  As another example, the inflow amount of treated water is measured, the Escherichia coli sensor is used to determine the concentration of treated water after disinfection, and it is fed back to the arithmetic unit to control the amount of disinfectant injected. Yes. In this case, in order to maintain the target value of the number of coliforms or coliform groups in the treated water after disinfection, the amount of disinfectant injected is controlled according to the deviation between the measured value and the target value (Patent Document) 2).

Japanese Patent No. 2720552 JP 2003-10857 A

  The conventional disinfection system is as described above, and the disinfection injection control determines the disinfection injection rate empirically or determines the residual chlorine concentration or coliform concentration or coliform concentration of treated water after disinfection. The injection rate of the disinfectant is determined by performing feedback control. However, the water quality changes from hour to hour, and it is difficult to cope with the change in water quality by the method of empirically determining the injection rate of the disinfectant. Therefore, in order to achieve water quality standards, it is necessary to inject an excessive amount of disinfectant, and the treated water after disinfection has a high concentration of disinfectant. If the sewage is affected, it has an adverse effect on the ecosystem where it is discharged, and there is a problem that an excessive amount of disinfectant is wasted and expensive.

  In addition, regarding the method of measuring and controlling the residual chlorine concentration of treated water after disinfection, the detection limit of residual chlorine is usually 0.1 mg / L, so it is difficult to maintain the residual chlorine concentration lower than this. there were.

  On the other hand, the standard value for the quality of clean water is that the number of coliforms is not detected, and the standard value for the quality of sewage has a discharge standard of 3000 coli / mL of coliforms, but we want to set it to 0 / mL when sewage is discharged. There are many requests. That is, it is necessary that the number of E. coli or coliform group is not detected or 0 / mL.

  However, in the method of measuring the number of coliforms or coliforms of treated water after disinfection as in the conventional disinfection system and controlling the injection amount of the disinfectant according to the deviation from the target value, Disinfectant injection cannot be performed without excess or deficiency so that the number of groups is 0 / mL. This is because it is impossible to obtain a measurement value of 0 or less E. coli group / mL, and therefore it is not possible to suppress excessive injection of the disinfectant. Therefore, it was impossible to inject a disinfectant such that the number of E. coli or coliforms or the number of microorganisms was almost 0 / mL.

  The present invention has been made to solve the above-described problems. A water disinfecting apparatus or disinfecting method that achieves a sufficient disinfectant injection while achieving a sufficient disinfecting effect, is provided. The purpose is to get.

The water disinfecting apparatus according to the present invention includes a disinfecting tank in which treated water and a disinfectant are mixed, a microorganism measuring apparatus for measuring an enzyme activity value of microorganisms in the treated water disinfected in the disinfecting tank, an enzyme activity value larger than 0, and From the control device and the control device that set the enzyme activity target value and control the amount of disinfectant injection so that the number of microorganisms in the treated water when measured by the culture method is smaller than the maximum non-detectable enzyme activity value And a disinfectant supply device for injecting a disinfectant based on the above signal.
The water disinfection method according to the present invention is a water disinfection method for measuring the enzyme activity value of microorganisms in treated water disinfected in a disinfection tank in which treated water and a disinfectant are mixed. The injection amount of the disinfectant is controlled such that the enzyme activity value of the microorganism is greater than 0 and the number of microorganisms in the treated water when measured by the culture method is smaller than the maximum enzyme activity value that is not detected.

  According to this invention, since it becomes possible to inject a disinfectant without excess or deficiency while obtaining a sufficient disinfecting effect, the residual concentration of the disinfectant can be made extremely low while the number of microorganisms after disinfection is not detected. It does not adversely affect the environment of the discharge destination.

  In addition, since the disinfectant can be injected without excess or deficiency, the running cost can be reduced without injecting useless disinfectant.

Embodiment 1 FIG.
First, the principle of the disinfection method of the present invention will be described. In the present invention, the Escherichia coli group count measuring apparatus shown in FIG. This Escherichia coli group number measuring apparatus measures the β-galactosidase activity value using an enzyme-catalyzed reaction by the enzyme β-galactosidase specifically possessed by the coliform group contained in the water to be treated.

  Specifically, 4-methylunveriferyl-β-galactopyranoside (4-MUG), which is a fluorescent enzyme substrate, is produced by enzyme catalysis of the enzyme β-galactosidase specifically possessed by coliforms. Veriferon (4-MU) is produced. By measuring the fluorescence intensity of 4-methylumbelliferone, the production rate of 4-methylumbelliferone can be calculated. This production rate is proportional to the amount of β-galactosidase originally contained in the sample water. Since the amount of β-galactosidase is proportional to the number of coliforms, the number of coliforms can be determined by measuring the production rate of 4-methylumbelliferone.

Next, the configuration of the Escherichia coli group number measuring apparatus of the present embodiment will be described. FIG. 1 is a diagram showing a configuration of an E. coli group count measuring apparatus.
The treated water is stored in the storage tank 17 via the water conduit 10. The storage tank 17 is open to atmospheric pressure. The storage tank 17 is connected to one of the first mixing portions 24 via a pipe 18. A pump 20 is provided in the middle of the pipe 18.
The mixed reagent container 25 contains a mixed reagent for performing an enzyme reaction. The mixed reagent is a mixture of a fluorescent enzyme substrate, a buffer, and a surfactant. Here, 4-methylumbelliferyl-β-galactopyranoside is used as a fluorescent enzyme substrate.

  The mixed reagent container 25 is connected to one side of the two-way electromagnetic valve 31 via the pipe 28. The other of the two-way solenoid valve 31 is connected to one of the first mixing portions 24 via a pipe 33. The remaining one of the first mixing portions 24 is connected to the reaction portion 35 via a pipe 34. The reaction portion 35 is a coiled tube and is housed in a constant temperature bath 40. The constant temperature bath 40 is maintained at a constant temperature, which is 38 ° C. here. The reaction part 35 is connected to one of the second mixing parts 41.

  The container 42 contains an alkaline aqueous solution, and here, a 3M glycine-sodium hydroxide solution is used. The container 42 is connected to one side of the two-way solenoid valve 45 by a pipe 43 via a pump 44. The other of the two-way solenoid valve 45 is connected to the second mixing portion 41 via a pipe 46. The remaining one of the second mixing portion 41 is connected to one end of a flow cell 49 in the detection portion 48 via a pipe 47.

  Here, a purple LED is used as the excitation light source 50 for measuring the fluorescence in the detection portion 48. Band pass filters 51 and 52 for passing only the effective wavelength of the excitation light and the wavelength spectrum of the fluorescence emitted from the flow cell 49, and a photomultiplier tube 53 for detecting the fluorescence are attached. The measurement wavelength of fluorescence was set to 450 nm here. For this, an appropriate one is selected according to the fluorescent substance to be measured. One of the flow cells 49 is connected to a waste liquid container 55 via a pipe 54. The output of the photomultiplier tube 53 is connected to an AD conversion board 57 via a cable 56, converted into a digital signal, and output to the outside via a cable 58.

  Next, the operation at the time of measurement of the Escherichia coli group counting device will be described with reference to FIG. In FIG. 1, the water to be treated guided through the water conduit 10 is stored in the water storage tank 17. The two-way solenoid valve 31 is opened and the pumps 20 and 30 are operated. The treated water and the mixed reagent are mixed in the first mixing portion 24 and the pipe 34 and sent to the reaction portion 35. Since there is water to be treated remaining in the piping of the reaction portion 35 at the previous measurement, the pumps 20 and 30 are operated until they are completely replaced. The pumps 20 and 30 are stopped while the inside of the reaction portion 35 is completely replaced, and the two-way solenoid valve 31 is closed. This time is set as 0 minute reaction time as the start time of the enzyme-catalyzed reaction. Hereinafter, the time of 1 minute after the start of the reaction is referred to as “1 minute of reaction”.

  In the reaction portion 35, 4-methylumbelliferone is produced from 4-methylumbelliferyl-β-galactopyranoside by the catalytic hydrolysis reaction of β-galactosidase of the coliform group. When the timer reaches 1 minute, the two-way solenoid valve 45 is opened, the pumps 20 and 44 are operated, and the reaction solution is sent to the flow cell 49. Due to the 3M glycine-sodium hydroxide solution sucked from the container 42, the reaction solution in the reaction portion 35 becomes alkaline and stops the enzyme-catalyzed reaction.

  The fluorescence intensity of the fluorescent substance produced by the reaction of the enzyme β-galactosidase with the fluorescent enzyme substrate is determined at a certain enzyme reaction time, for example, 1 minute reaction time, 10 minutes reaction time, 20 minutes reaction time, A total of 4 measurements are taken at 30 minutes, the slope, that is, the production rate, is determined, and the β-galactosidase activity value is determined as the enzyme activity value. When 4-methylumbelliferyl-β-galactopyranoside is used as the fluorescent enzyme substrate, the fluorescent substance is 4-methylumbelliferone, and the unit of β-galactosidase activity value is μg / L · min. is there.

By the way, the inventors investigated the relationship between the number of coliforms by the desoxycholate agar medium method and the above-mentioned enzyme activity value β-galactosidase activity value when chlorine disinfection was performed, and have specific characteristics. I found out. In the experiment, using the clarified water before disinfection, the chlorine injection rate was changed between 0 and 2 mg / L, and the number of E. coli groups and the β-galactosidase activity value were measured by the E. coli group number measuring device. FIG. 2 shows the relationship between the number of coliforms and the β-galactosidase activity value by the desoxycholate agar medium method. In FIG. 2, the horizontal axis represents the number of coliforms, and the vertical axis represents the β-galactosidase activity value. FIG. 3 shows the contents of FIG. 2 as conceptually divided into three parts.
Here, in FIG. 2, the numbers indicate the chlorine injection rates in the respective plots. From this, it can be seen that as the chlorine injection rate increases, the number of coliforms and the value of β-galactosidase activity decrease.
Furthermore, the relationship between the chlorine injection rate and the residual chlorine concentration in this case is shown in FIG. In FIG. 4, the horizontal axis represents the chlorine injection rate (mg / L), and the vertical axis represents the residual chlorine concentration (mg / L). The numbers assigned to the plots correspond to the numbers in FIG.

First, let us consider a case where the chlorine injection rate in the state A in FIGS.
In this case, since the amount of chlorine is not sufficient as compared with the number of coliforms to be sterilized, as the chlorine injection rate increases as shown in the state of FIG. The zase activity value decreases proportionally with the number of coliforms. At that time, since all the chlorine is consumed, the residual chlorine concentration becomes 0 mg / L as shown in the state of FIG.

Next, the case where the chlorine injection rate in the state of B in FIGS. 3 and 4 is about 0.5 to 1 mg / L is shown.
In this case, the relationship between the β-galactosidase activity value and the number of coliforms is as shown in FIG. Even in this case, the amount of chlorine is not sufficient as compared with the number of coliforms, and the number of coliforms decreases as the chlorine injection rate increases. However, the β-galactosidase activity value does not decrease so much as compared to the number of coliforms. Since the chlorine injection rate at this time is not sufficient to sterilize all coliforms, chlorine is almost consumed, and the residual chlorine concentration becomes 0.01 mg / L or less as shown in FIG.

Furthermore, the case where the chlorine injection rate which is the state of C of FIG. 3 and FIG. 4 is 1 mg / L to 1.5 mg / L is shown.
In this case, as shown in FIG. 3C, the number of coliforms by the desoxycholate agar method is not detected.
Usually, in the desoxycholate agar medium method, the sample to be measured is measured as it is without dilution, and when 1 mL of sample water is mixed in one dish, one colony is formed on the agar medium. This value is 1 piece / mL, and this value is the minimum resolution. Therefore, if no colonies are formed, it is not detected, and the number of coliforms is not exactly 0 / mL. However, since it is below the detection limit, it can be considered that no coliforms exist (0 / mL). .

  At this time, as shown in FIG. 3, the β-galactosidase activity value continuously changes from the state of B in FIG. 3, and the β-galactosidase activity value is not 0 but becomes a measurable value. If the chlorine injection rate is further increased, the β-galactosidase activity value decreases and finally becomes zero. That is, the β-galactosidase activity value continuously changes according to the chlorine injection rate even in the region where the number of coliforms is not detected by the desoxycholate agar medium method.

  The residual chlorine concentration in this case is 0.01 to 0.05 mg / L as shown in FIG. If the chlorine injection rate is further increased, all coliforms are sterilized, so no further chlorine is consumed. Therefore, the residual chlorine concentration increased in proportion to the increase of the chlorine injection rate, and became 0.05 mg / L or more.

  The cause of the phenomenon shown in FIG. 3 and FIG. 4C can be explained as follows. The total of free chlorine and combined chlorine is residual chlorine. In the case of residual chlorine having an extremely low concentration of 0.01 to 0.05 mg / L, the residual chlorine permeates only the cell membrane of the coliform group but cannot penetrate into the inside.

  As a result, the cell membrane of the Escherichia coli group becomes damaged and is not grown on a selective medium such as desoxycholate agar medium, and is not detected. This state is known as a VBNC (Viable But Non-Culturable) state in which cells cannot be cultured even though the cells are alive, and is a measurement method other than the desoxycholate agar medium method, such as a specific enzyme substrate medium method (MMO- This is a phenomenon that occurs even in the MUG method).

  On the other hand, enzymes such as β-galactosidase present in the cells remain without losing enzyme activity. Therefore, as shown in FIG. 3C, the number of coliforms by the desoxycholate agar medium method is not detected, but the β-galactosidase activity value exists. As the chlorine injection rate increases, the residual chlorine concentration also increases. Residual chlorine can completely permeate the cell membrane of the coliform group and penetrate into the cell membrane, so that it acts on the enzyme system to sterilize and the enzyme is inactivated by residual chlorine. When residual chlorine is present in water, all extracellular enzymes are inactivated. Therefore, in this case, the number of coliforms and the β-galactosidase activity value by the desoxycholate agar medium method become zero.

  That is, there is a region C in FIG. 3 and FIG. 4 in which the number of coliforms is not detected and the residual chlorine concentration can be kept low, and in this region, a range of a value having a β-galactosidase activity value. I found out.

  By utilizing this characteristic, by controlling the β-galactosidase activity value within a certain range, it is possible to maintain the residual chlorine concentration at a very low concentration while keeping the number of coliforms undetected. .

  For example, in the case of FIG. 2, the β-galactosidase activity value, that is, the maximum enzyme activity value when transitioning from the B state to the C state is regarded as about 0.3 μg / L · min. That is, a value that is smaller than the maximum enzyme activity value at which the number of microorganisms is not detected and the enzyme activity value is greater than 0, for example, 0.1 μg / L · min is set as the enzyme activity target value, and the chlorine injection rate ( If the amount of sodium hypochlorite injection) is controlled, the number of coliforms can be made non-detectable. Further, the residual chlorine concentration at this time becomes 0.05 mg / L or less, and it becomes possible to perform disinfection without excess and deficiency with the minimum amount of chlorine.

Although it is desirable to use feedback control as the control method, it is not particularly limited to this. As an example of the control equation, the following equation may be used in which the injection rate is corrected with the measured value of the coliform count device in the proportional control with respect to the conventionally used flow rate.
_{C l = k 1 × Q +} k 2 · (C * -C) + k 3 · Σ (C * -C) (1)
Here, C _l : chlorine injection rate (mg / L)
k ₁ : coefficient of flow rate term Q: flow rate (m ³ / hr)
k ₂ : Coefficient of deviation term C ^* : Target value for the number of coliforms (pieces / mL)
C: Measured value of the number of coliforms (pieces / mL)
k: Coefficient of integral term. Here, the coefficients k ₁ , k ₂ and k ₃ are values determined in advance by simulation or the like.

  Further, when the measurement sample having a residual chlorine concentration of 0.1 mg / L or more was filtered through a filter having a pore size of 0.4 μm and the coliform group was removed, the β-galactosidase activity value was determined using the background as a sample. It was 005 μg / L · min. Thus, even when a filter-filtered sample without the coliform group is measured, the background value is measured. The value obtained by subtracting the background value from the β-galactosidase activity value at the point where the state changes from B to C in FIG. What is necessary is just to use the value between them as a ground value as a target value. In addition, since the measurement error of the β-galactosidase activity value is approximately ± 10%, the control value is set between 10% and 90% of the maximum β-galactosidase activity value when the number of coliforms is not detected. It is desirable. More desirably, when the value between 20% and 80% is set as the management value, more stable control can be performed on the safer side.

  Specifically, since the β-galactosidase activity value at the time of transition from the state B in FIG. 3 to the state C is 0.3 μg / L · min as described above, the target value is from 0.03. The amount may be 0.27 μg / L · min, more preferably 0.06 to 0.24 μg / L · min.

Next, the overall configuration of the water disinfection apparatus using the relationship between the number of coliforms and the β-galactosidase activity value by the desoxycholate agar medium method described above, that is, equipped with the coliform measurement apparatus will be described.
FIG. 5 is an overall configuration diagram of a disinfection system using the water disinfection device of Embodiment 1 of the present invention.

  This disinfection system consists of a sedimentation basin 1 for sedimenting wastewater sand and coarse waste, an activated sludge treatment tank 3 for decomposing organic matter by the action of microorganisms in the activated sludge, and a final sedimentation basin 4 for sedimenting floating sludge. It has the water disinfection apparatus 100 of the form. In addition, the sedimentation basin 1 and the activated sludge treatment tank 3 are connected to the sedimentation basin 6, the activated sludge treatment tank 3, the final sedimentation basin 4, and the disinfection apparatus 100 in this order by the pipe 6 b and the activated sludge treatment tank 3. The sludge treatment tank 3 and the final sedimentation basin 4 are connected by a pipe tub 6c, and the final sedimentation basin 4 and the disinfection device 100 are connected by a pipe tub 6d. Furthermore, it has a pipe 6a for flowing waste water into the sedimentation basin 1 and a pipe 6e for discharging the sterilized water sterilized by this disinfection system to the river or the sea.

  Next, operation | movement of the disinfection system of this Embodiment is demonstrated. Inflow sewage, which is waste water from homes and factories, first flows into the sedimentation basin 1 through the pipe 6a, precipitates sand and coarse garbage, and is sent to the activated sludge treatment tank 3 through the pipe 6b.

  In the activated sludge treatment tank 3, organic substances are decomposed by the action of microorganisms in the activated sludge. Further, the treated water is sent to the final sedimentation basin 4 through the pipe tub 6c, and the suspended sludge is settled. The settled water after the sludge settles is sent to the disinfection device 100 through the tube 6d and sterilized, and the sterilized water is discharged to the river and the sea through the tube 6e.

Next, the structure of the disinfection apparatus 100 of this Embodiment is demonstrated based on FIG.
The disinfecting apparatus 100 has a disinfecting tank 7 and a flow meter 9 installed in the tube 6d. Furthermore, it has the water conduit 10, the pump 11, and the coliform group number measuring apparatus 12 which send the disinfection treated water of the tube 6e to the coliform group number measuring apparatus 12. Moreover, it also has the drain pipe 60 connected so that the waste_water | drain after measuring with the coliform group number measuring apparatus 12 may be drained to the pipe rod 6e. Moreover, it has the control apparatus 13 which controls the amount of the disinfectant inject | poured by the data obtained from the flowmeter 9 and the coliform group number measuring apparatus 12. FIG.

  Further, the disinfecting apparatus 100 also includes a disinfectant supply apparatus 110 that supplies the disinfectant to the disinfecting tank 7. The disinfectant supply device 110 includes a sodium hypochlorite tank 14 for storing sodium hypochlorite as a disinfectant, a pump 15 for feeding sodium hypochlorite, and a water conduit 16. Here, the pump 15 is connected to the control device 13 so as to operate according to a control signal of the control device 13.

Next, the operation of the disinfection apparatus 100 will be described.
The flow rate of the water flowing into the disinfection device 100 is measured by the flow meter 9, and the obtained flow rate signal is sent to the operation control device 13. Further, the sterilized water is collected by the pump 11 through the water conduit 10 and sent to the coliform count measuring device 12. This E. coli group number measuring apparatus has the configuration shown in FIG. 1 described above, and measures the β-galactosidase activity value, which is the enzyme activity value. This measured value is sent to the control device 13. From the measured value of the flow rate and the β-galactosidase activity value, the control device 13 determines the chlorine injection rate using, for example, equation (1). The chlorine injection amount is determined by multiplying the measured flow rate by the determined chlorine injection rate. In the disinfectant supply device 110 based on the determined chlorine injection amount, the rotation speed of the pump 15 is set, and sodium hypochlorite is sent from the sodium hypochlorite tank 14 through the water conduit 16. Sodium hypochlorite is injected immediately before the disinfection tank 7, and the injected sodium hypochlorite is changed into chlorine and hypochlorite ions in water, and disinfection is performed. The disinfection tank 7 has a U-shaped flow path so that a constant residence time is maintained, and the residence time depends on the flow rate, but is usually set between 5 minutes and 15 minutes.

  Since the disinfecting apparatus is configured as described above, the disinfectant can be controlled using the β-galactosidase activity value as an index instead of the number of coliforms. By doing so, the number of coliforms is not detected, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

  Here, the flow meter 9 is provided and controlled by measuring the flow rate. However, if the flow rate can be predicted in advance, it is not necessary to provide the flow meter 9 and the control is performed only by the enzyme activity value of the coliform count measuring device 12. can do. If it does so, the disinfection apparatus with a simpler apparatus structure can be obtained.

  Moreover, in this embodiment, the case where chlorine disinfection was performed using sodium hypochlorite as a disinfectant was shown, but the same applies when other halogen-based disinfectants are used. For example, even when the same chlorine-based sodium isocyanurate or bromine-based sodium hypobromite is used, the same applies. The sterilization mechanism of the halogen-based disinfectant is almost the same, and as long as the characteristics of FIG. 3 are shown, the same disinfectant injection control is possible.

  Furthermore, the same effect can be obtained when a bactericide is used so that Escherichia coli or coliforms become VBNC.

Embodiment 2. FIG.
In the second embodiment, the β-galactosidase activity value is manually analyzed in the disinfection device of the first embodiment without using the Escherichia coli group counting device 12, and the obtained β-galactosidase activity value is obtained. It is used to control disinfectant injection. This is all manually performed in Embodiment 1, and is performed manually. If measurement is performed using the same measurement principle, the same disinfectant injection control can be realized. The specific operation of the manual analysis is as follows.

  Disinfecting water containing coliforms and a mixed reagent containing a fluorescent enzyme substrate are mixed and placed in a constant temperature state of 37-38 ° C. to cause an enzyme reaction. The fluorescent substance produced by the reaction of the enzyme β-galactosidase with the fluorescent enzyme substrate is measured every certain enzyme reaction time. For example, 1 minute, 10 minutes, 20 minutes, and 30 minutes for each of 4 times in total. Fluorescence intensity is measured with a fluorimeter and converted to fluorescent substance concentration. A regression line is obtained from a time change plot of 1 minute, 10 minutes, 20 minutes, and 30 minutes, and a slope is obtained to obtain an enzyme activity value. The obtained enzyme activity value is input to the operation control device, and injection control of sodium hypochlorite is performed according to a preset enzyme activity target value. As in Embodiment 1, when the fluorescent enzyme substrate uses 4-methylumbelliferyl-β-galactopyranoside, the enzyme activity value is the β-galactosidase activity value.

  Here, as the enzyme activity target value, similarly to the first embodiment, the maximum enzyme activity value at which the coliform group is not detected is set as the upper limit, the lower limit is set as the background value, and the value therebetween is set as the target value. In addition, since the measurement error of the β-galactosidase activity value is approximately ± 10%, the control value is set between 10% and 90% of the maximum β-galactosidase activity value when the number of coliforms is not detected. It is desirable. More desirably, when the value between 20% and 80% is set as the management value, more stable control can be performed on the safer side.

  According to this embodiment, it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination while obtaining a sufficient disinfecting effect.

Embodiment 3 FIG.
Embodiment 3 focuses on β-glucuronidase specific for E. coli, not β-galactosidase specific for E. coli as an enzyme in Embodiment 1.
As a public health indicator, E. coli may be used instead of coliforms. For example, as already mentioned, E. coli is not detected in tap water. Therefore, it is necessary to use not the number of coliforms but the number of coliforms as an index.

  The disinfection system of the present embodiment is almost the same as that of the first embodiment shown in FIG. 5 except that an E. coli count measuring device is used instead of the E. coli group count measuring device 12. The configuration of the E. coli number measuring apparatus is the same as that of the E. coli group number measuring apparatus 12 shown in FIG. 2, but the reagents used are different. Here, 4-methylumbelliferyl-β-glucuronide is used instead of 4-methylumbelliferyl-β-galactopyranoside as the fluorescent enzyme substrate of the mixed reagent contained in the mixed reagent container 25. The fluorescent material obtained by the enzyme reaction is 4-methylumbelliferone as in the first embodiment. FIG. 6 shows the experimental results of examining the number of E. coli and the β-glucuronidase activity value at the time of chlorine disinfection using clarified water in the same manner as in the first embodiment. Here, the chlorine injection rate increases in the order of the numbers given to the plot of FIG. That is, as the chlorine injection rate increases, the number of coliforms and the β-galactosidase activity value decrease. At this time, the MMO-MUG method was used to measure the number of E. coli.

  The experimental results tend to be similar to those in FIG. 3, and it can be seen that the same results as those in FIG. 4 can be considered as in the case of β-galactosidase. Therefore, the target value of the β-glucuronidase activity value of this embodiment is set to the maximum enzyme activity value at which E. coli is not detected as the upper limit, and the lower limit is the background value as in the first embodiment. It can be a value. Moreover, since the measurement error of the β-glucuronidase activity value is approximately ± 10%, the control value is between 10% and 90% of the maximum β-glucuronidase activity value when the number of E. coli is not detected. It is desirable to set More desirably, when the value between 20% and 80% is set as the management value, more stable control can be performed on the safer side. In the present embodiment, the β-glucuronidase activity value may be 0.03 to 0.27 μg / L · min, more preferably 0.06 to 0.24 μg / L · min.

  In this embodiment, as in Embodiment 1, E. coli to be sterilized is not detected, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

Embodiment 4 FIG.
In this embodiment, 4-trifluoroumbelliferyl-β-galactopyranoside is used in place of 4-methylumbelliferyl-β-galactopyranoside used in the first embodiment. This fluorescent enzyme substrate reacts with β-galactosidase in the same manner as 4-methylumbelliferyl-β-galactopyranoside, but 4-trifluoroumbelliferone is generated as a fluorescent substance generated after the reaction. This fluorescent substance has an excitation wavelength different from that of 4-methylumbelliferone, and is optimal around 390 nm, and the fluorescence wavelength is 490 nm.

  Therefore, in FIG. 1, it is necessary to change the specifications of the excitation light source 50, the bandpass filters 51 and 52, and the photomultiplier tube 53 in accordance with them. However, since the configuration and operation are exactly the same as those in the first embodiment, description thereof is omitted. Using the obtained β-galactosidase activity value, the chlorine injection rate can be similarly controlled. As in Embodiment 1, an experiment was conducted to compare the β-galactosidase activity value with the number of coliforms when this fluorescent enzyme substrate was used during chlorine disinfection. The results showed the same tendency as the characteristic diagram of FIG. 4, but the β-galactosidase activity value at the transition from the state B to the state C in FIG. 4 was about 0.1 μg / L · min. The result was different from 1.

  From this result, the maximum enzyme activity value at which the coliform group is not detected is set as the upper limit, the lower limit is set as the background value, and the value therebetween is set as the target value. In addition, since the measurement error of the β-galactosidase activity value is approximately ± 10%, the control value is set between 10% and 90% of the maximum β-galactosidase activity value when the number of coliforms is not detected. It is desirable. More desirably, when the value between 20% and 80% is set as the management value, more stable control can be performed on the safer side.

  Therefore, the target enzyme activity of β-galactosidase in this embodiment may be 0.01 to 0.09 μg / L · min, preferably 0.02 to 0.08 μg / L · min.

  According to this embodiment, the coliform group to be sterilized is not detected as in the first embodiment, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

Embodiment 5. FIG.
In this embodiment, 4-trifluoroumbelliferyl-β-glucuronide is used instead of 4-trifluoroumbelliferyl-β-galactopyranoside used in the fourth embodiment. The rest of the configuration is the same as that of the fourth embodiment, and a description thereof is omitted. This substrate reacts specifically with β-glucuronidase to produce 4-trifluoroumbelliferone. Accordingly, the point that the water quality index is changed from E. coli group to E. coli is different from the focused enzyme and the fluorescent enzyme substrate, and the other points are exactly the same as in the fourth embodiment.

  According to this embodiment, as in the fourth embodiment, E. coli to be sterilized is not detected, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

Embodiment 6 FIG.
In this embodiment, esterase is used as the enzyme of interest. An esterase is an enzyme possessed by a general bacterium, and can be regarded as an enzyme activity of the general bacterium. Since other configurations and operations are the same as those of the first embodiment, description thereof is omitted.

4-methylumbelliferyl-acetate is used as a fluorescent enzyme substrate at this time. When esterase reacts with 4-methylumbelliferyl-acetate, 4-methylumbelliferone is produced. As for the esterase activity value, which is the output value of the general bacterial count measuring device, as a result of examining the general bacterial count and the esterase activity value at the time of chlorine disinfection as in the first embodiment, the characteristic diagram of FIG. It was found that the same tendency as in the case of β-galactosidase may be considered. At this time, the number of general bacteria was measured using a standard agar medium method.

  Therefore, since it may be considered to be the same as the characteristic of FIG. 3 as in the case of β-galactosidase of Embodiment 1, the maximum enzyme activity value at which general bacteria are not detected is set as the upper limit, and the lower limit is set as the background value. The value may be a target value. In addition, since the measurement error of the esterase activity value is approximately ± 10%, it is between 10% and 90% of the maximum esterase activity value when the number of general bacteria is not detected or 0 / mL. It is desirable to set management values. More desirably, when the value between 20% and 80% is set as the management value, more stable control can be performed on the safer side.

  According to this embodiment, the number of general bacteria to be sterilized is not detected, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

Embodiment 7 FIG.
In the present embodiment, the enzyme to be focused on is esterase as in Embodiment 6, except that 4-trifluoroumbelliferyl-acetate is used as the fluorescent enzyme substrate to be used. 4-trifluoroumbelliferyl-acetate is degraded by esterase to produce 4-trifluoroumbelliferone.
The configuration of this embodiment is the same as that of the fourth embodiment, and detailed description thereof is omitted.

  According to this embodiment, general bacteria to be sterilized are not detected, and the residual chlorine concentration can be 0.05 mg / L or less. Therefore, while obtaining a sufficient disinfecting effect, there is a remarkable effect that it is possible to achieve both the cost saving of the disinfectant and the environmental conservation of the discharge destination.

It is a block diagram which shows the coliform group number measuring apparatus of Embodiment 1 of this invention. It is a figure which shows the result of having measured the relationship between the coliform group number by Embodiment 1 of this invention, and (beta) -galactosidase activity value. It is a figure which shows the relationship between the coliform group number by embodiment 1 of this invention, and (beta) -galactosidase activity value. It is a figure which shows the relationship between the chlorine injection rate by Embodiment 1 of this invention, and residual chlorine concentration. It is a whole block diagram of the disinfection system using the disinfection apparatus of Embodiment 1 of this invention. It is a figure which shows the result of having measured the relationship between the number of colon_bacillus | E._coli and β-glucuronidase activity value by Embodiment 3 of this invention.

Explanation of symbols

1 sedimentation basin, 3 activated sludge treatment tank, 4 final sedimentation basin, 6a, 6b, 6c, 6d, 6e pipe tub, 7 disinfection tank, 9 flow meter, 10 water conduit, 11 pump, 12 E. coli group number measuring device, 13 Operation control device, 14 sodium hypochlorite tank, 15 pump, 16 introduction pipe, 17 storage tank, 18, 21, 28, 32, 33, 34, 43, 46, 47, 54 piping, 20 pump, 24 1st 25 mixing reagent container, 30 pump, 31 two-way solenoid valve, 35 reaction part, 40 thermostat, 41 second mixing part, 42 container, 44 pump, 45 two-way solenoid valve, 48 detection part, 49 Flow cell, 50 Excitation light source, 51, 52 Band pass filter, 53 Photomultiplier tube, 55 Waste liquid container, 56, 58 cable, 57 AD conversion board, 60 Drain pipe, 100 Disinfection device, 110 Poison agent supply device.

Claims (8)

Disinfection tank in which treated water and disinfectant are mixed, microorganism measuring apparatus for measuring enzyme activity value of microorganisms in treated water disinfected in the disinfecting tank, and treatment when the enzyme activity value is larger than 0 and measured by a culture method Set the target enzyme activity value so that the number of microorganisms in the water is less than the maximum non-detectable enzyme activity value , and control the disinfectant injection amount and the disinfectant based on the signal from the control device A water disinfection device having a disinfectant supply device for injecting. A flow meter for measuring the flow rate of the treated water supplied to the disinfection tank, and the enzyme activity value is 0 based on the flow rate of the treated water measured by the flow meter and the enzyme activity value measured by the microorganism measuring apparatus. The water disinfection device according to claim 1, further comprising a control device for controlling the amount of the disinfectant injected so that the number of microorganisms when measured by a culture method is smaller than a maximum enzyme activity value that is not detected. In the control device, the disinfectant injection amount is controlled so that the number of microorganisms when the enzyme activity value is measured by a culture method is 10% or more and 90% or less of the maximum enzyme activity value that is not detected. The water disinfection device according to claim 1 or 2. The water disinfection device according to any one of claims 1 to 3, wherein the disinfectant is a halogen-based disinfectant. The water disinfection apparatus according to any one of claims 1 to 4, wherein the enzyme measured as the enzyme activity value is β-galactosidase. The water disinfection apparatus according to any one of claims 1 to 4, wherein the enzyme measured as the enzyme activity value is β-glucuronidase. A water disinfection method for measuring an enzyme activity value of microorganisms in the treated water disinfected in a disinfection tank in which treated water and a disinfectant are mixed,
As the number of microorganisms of the treated water when the enzyme activity of the microorganisms disinfected the treated water was measured by larger and culture than 0 is smaller than the maximum enzyme activity as the non-detection, enzyme activity A method for disinfecting water , comprising setting a target value and controlling the amount of the disinfectant injected. The amount of the disinfectant injected is controlled so that the enzyme activity value is 10% or more and 90% or less of the maximum enzyme activity value when the number of microorganisms is not detected when measured by a culture method. Item 8. A method for disinfecting water according to Item 7.

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