JP4468221B2 - Water treatment system using ultraviolet irradiation - Google Patents

Description

  The present invention relates to a water treatment system that performs water purification using ultraviolet irradiation.

  Conventionally, water treatment systems represented by water supply have been operated on the basis of sanitary safety by chlorination. However, in recent years, water pollution accidents have occurred due to emerging or reviving pathogenic microorganisms such as Cryptosporidium and Giardia.

  In addition, algae generated in large quantities due to eutrophication of lakes, dams and rivers that are the source of tap water, and the progress of organic pollution, have a bad smell, coloring disturbance, aggregation, sedimentation inhibition, filtration clogging, and leakage leakage into filtered water. A situation has occurred.

  Furthermore, there is a problem that a chlorine agent injected for sterilization reacts with organic substances in the raw water to generate harmful by-products (such as trihalomethane). Such a situation cannot be handled by a conventional water treatment system having only basic treatment steps including aggregation, precipitation, filtration, and chlorination.

  Against this background, sterilization (disinfection) technology by ultraviolet irradiation treatment (hereinafter sometimes referred to as ultraviolet disinfection) has attracted attention as an alternative sterilization technology for conventional chlorination. Ultraviolet disinfection has the advantage that it does not require complex chemical injection management and does not generate harmful byproducts. For this reason, in a water treatment plant etc., an ultraviolet irradiation process may be employ | adopted for the purpose of sterilization or oxidation of a residual organic substance. However, from the viewpoint of ultraviolet transmission efficiency, generally, a treatment for irradiating the filtered water or the agglomerated / precipitated water with ultraviolet rays is performed.

  On the other hand, when aiming at aggregation improvement or loss of infectivity of pathogenic protozoa such as Cryptosporidium, there is a treatment of irradiating raw water with ultraviolet rays. This is a process of irradiating ultraviolet rays instead of chlorination. As described above, unlike chlorine, ultraviolet rays do not produce by-products such as trihalomethane, and they are highly effective in damaging the growth ability of cryptosporidium and eliminating infectivity. Therefore, the ultraviolet irradiation treatment can effectively use the merits of the ultraviolet rays.

  In addition, it is suitable that the algae contained in the raw water is not propagated in the water purification treatment, and it has been confirmed that the ultraviolet irradiation treatment is effective as a treatment for preventing the algae from breeding.

  By the way, the irradiation efficiency of ultraviolet rays changes depending on the turbidity and chromaticity of water to be treated. In the ultraviolet irradiation treatment, since it is particularly difficult to control the quality of raw water, there is a problem that it is difficult to maintain the irradiation efficiency of ultraviolet rays at an appropriate level.

  In order to solve such a point, the turbidity of the raw water is detected, and appropriate ultraviolet irradiation control is realized by controlling the flow rate of the raw water flowing through the water pipe containing the ultraviolet lamp according to the detected turbidity. A technique for this has been proposed (see, for example, Patent Document 1). This document proposes the use of ultraviolet irradiation in the algaecidal treatment of underwater plankton in a reservoir or the like.

In addition, a technique for realizing appropriate ultraviolet irradiation control by using a fine particle meter instead of a turbidimeter has also been proposed (see, for example, Non-Patent Document 1). Furthermore, an ultraviolet irradiation system that controls ultraviolet lamp output using a turbidimeter and a particle meter in combination with a system that irradiates raw water with ultraviolet rays at a water treatment plant has been proposed (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 5-169059 JP 2004-188273 A Shigeo Kimura et al. “Survey on Basic Performance Evaluation of Particle Measuring Instruments”, Journal of Water Supply Association, Vol. 71, No. 10, pp. 31-51, published in October 2002

  The ultraviolet irradiation system and the ultraviolet irradiation processing method described in the above-mentioned prior art documents have the following problems.

  In general, simply irradiating the treated water after flocculation / precipitation treatment with ultraviolet rays cannot cope with countermeasures against algae that cause damage to flocculation / precipitation. In order to use the ultraviolet irradiation effect as a countermeasure against algae, it is necessary to irradiate the raw water before the aggregation treatment with ultraviolet rays.

  However, the quality of raw water changes greatly due to fluctuations in the water source and weather. In other words, the turbidity of raw water, the number of fine particles, and the concentration of organic matter greatly change due to a large amount of algae and rainfall, and usually the ultraviolet transmittance decreases due to these increases. As a result, there is a problem that the effect of ultraviolet irradiation cannot be sufficiently exhibited, and not only the countermeasure against algae but also the effect of sterilization (disinfection) treatment of pathogenic bacteria and the like is reduced.

  Then, the objective of this invention is providing the system which can exhibit an ultraviolet irradiation effect in the water treatment system using ultraviolet irradiation for algae countermeasure, bactericidal treatment, such as pathogen.

  The viewpoint of the present invention is to enable the effects of ultraviolet irradiation suitable for the water quality fluctuation of treated water, to prevent algae that impede water purification treatment, sterilization (disinfection) treatment of pathogenic bacteria, inactivation of microorganisms and pathogenic protozoa Or it is a water treatment system that realizes harmlessness.

A water treatment system according to an aspect of the present invention is a water treatment system that performs water purification treatment by irradiation with ultraviolet rays. In the subsequent stage of the water purification treatment process, a second ultraviolet irradiation apparatus for irradiating ultraviolet light, a control means for controlling the first and second ultraviolet irradiation apparatuses, and the first A first ultraviolet illuminance meter for measuring the ultraviolet illuminance in the ultraviolet irradiating device, and the control means includes an ultraviolet light amount target value based on an ultraviolet irradiation effect, a flow rate measurement value of raw water, a residence time, and the An arithmetic expression for calculating an ultraviolet illuminance target value is set based on the ultraviolet light amount target value, and the measured value of the first ultraviolet illuminance meter and the ultraviolet illuminance target value calculated by the arithmetic expression In comparison, when the comparison result is larger than the ultraviolet illuminance target value, control is performed to increase the output of the ultraviolet lamp in the first ultraviolet irradiation device, and the comparison result is the ultraviolet illuminance target value. When this is smaller, the control is performed so as to decrease the output of the ultraviolet lamp in the first ultraviolet irradiation device .

  ADVANTAGE OF THE INVENTION According to this invention, the water treatment system which exhibits an ultraviolet irradiation effect for algae measures, disinfection (disinfection) processing, such as a pathogenic microbe, and implement | achieves a reliable water purification process can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing a main part of a water treatment system using ultraviolet irradiation according to this embodiment.

  This system has a sand basin 1 for introducing raw water pumped at a water intake (not shown) through a water conduit, and a landing well 2 for temporarily storing the water through the sand basin 1. The amount of water sent to the water purification process is adjusted by the landing well 2.

  Furthermore, this system has a flocculation / sedimentation basin 3 for introducing the raw water sent from the landing well 2 through the pretreatment process. In the pre-treatment process, the raw water flow meter 4 and the first ultraviolet irradiation device (hereinafter sometimes referred to as the pre-ultraviolet irradiation device) are provided in the middle of the piping for sending the raw water from the landing well 2 to the aggregation / sedimentation basin 3. 5 is installed. In addition, a bypass pipe 6 is provided for the raw water to bypass the upstream ultraviolet irradiation device 5.

  The bypass pipe 6 is connected to the inlet side of the front ultraviolet irradiation device 5 via an inlet three-way valve 7a, and is connected to the outlet side thereof via an outlet three-way valve 7b. The inlet three-way valve 7a and the outlet three-way valve 7b are valves for switching the flow path of the raw water. In the middle of the piping, the water irradiated with ultraviolet rays by the former ultraviolet irradiation device 5 is sent to the coagulation / sedimentation basin 3.

  In the flocculation / sedimentation basin 3, a flocculating agent is injected, and turbidity in the raw water is removed by a procedure of rapid stirring, slow stirring, and precipitation. Specifically, fine sand and mud, colloidal organic substances, and the like gather to form a flock, and turbidity is precipitated and removed. At this time, a part of the algae and pathogenic microorganisms that have been killed or survived by the ultraviolet irradiation by the front-stage ultraviolet irradiation device 5 are also taken into the floc and removed.

  Furthermore, in this system, in the latter stage treatment process, the precipitation water flow meter 9 and the second ultraviolet ray irradiation device (hereinafter, the latter stage ultraviolet ray irradiation) are also provided in the middle of the piping for sending the treated water from the aggregation / sedimentation basin 3 to the filtration basin 8. 10 is sometimes installed).

  Further, a bypass pipe 11 is provided for the treated water to bypass the rear-stage ultraviolet irradiation device 10. The bypass pipe 11 is connected to the inlet side of the rear ultraviolet irradiation device 10 via the inlet three-way valve 12a, and is connected to the outlet side thereof via the outlet three-way valve 12b. The inlet three-way valve 12a and the outlet three-way valve 12b are valves for switching the flow path of the raw water. In the middle of the piping, the treated water irradiated with ultraviolet rays by the former ultraviolet irradiation device 5 is sent to the filter basin 8.

  A plurality of ultraviolet lamps for irradiating ultraviolet rays are installed in each of the front-stage ultraviolet irradiation apparatus 5 and the rear-stage ultraviolet irradiation apparatus 10. Each ultraviolet lamp is lit by power supplied from the ultraviolet lamp power supply devices 13a and 13b.

  A water purification treatment monitoring control device (hereinafter referred to as a controller) 14 of this system is connected to the ultraviolet lamp power supply devices 13a and 13b via control signal lines, and controls the outputs of the power supply devices 13a and 13b. The power supply amount to each ultraviolet lamp of the ultraviolet irradiation devices 5 and 10 is adjusted.

  The controller 14 inputs the measured value of the raw water flow rate from the raw water flow meter 4 included in the preceding treatment step, and inputs the measured value of the precipitated water flow rate from the precipitated water flow meter 9 included in the subsequent treatment step. Further, the controller 14 inputs the ultraviolet transmittance of the raw water measured by the raw water ultraviolet transmittance meter 16 and also inputs the ultraviolet transmittance of the precipitated water measured by the precipitated water ultraviolet transmittance meter 18.

  The raw water ultraviolet transmittance meter 16 is connected to the raw water sampling pipe 15 and measures the ultraviolet transmittance of the raw water sample sampled by the raw water sampling pipe 15 from the pipe connecting the landing well 2 and the previous stage ultraviolet irradiation device 5. On the other hand, the precipitated water ultraviolet transmittance meter 18 is connected to the precipitated water sampling pipe 17, and the precipitated water sampled by the precipitated water sampling pipe 17 from the pipe between the flocculation / sedimentation basin 3 and the subsequent ultraviolet irradiation device 10. Measure the UV transmittance of the sample.

  Furthermore, ultraviolet illuminance meters 19 and 20 for detecting the illuminance at an arbitrary point inside are installed in each of the front ultraviolet irradiation device 5 and the rear ultraviolet irradiation device 10. The controller 14 inputs measurement values from the ultraviolet illuminance meters 19 and 20.

(Operational effects of the first embodiment)
Hereinafter, the operational effects relating to the present embodiment will be described.

The controller 14 calculates the ultraviolet illuminance inside each of the front-stage ultraviolet irradiation device 5 and the rear-stage ultraviolet irradiation device 10 using the following formula (1). Here, the ultraviolet illuminance is maximum on the surface of the ultraviolet lamp, and gradually decreases as the distance from the lamp increases. The amount of decrease at this time can be calculated from the ultraviolet transmittance of the fluid to be treated (raw water or precipitated water) flowing through the pipe and the distance from the lamp surface.

Here, I is the ultraviolet illuminance (mW / cm ² ), U _v is the ultraviolet output (mW) of the lamp, T is the ultraviolet transmittance (%), Z ₀ is the distance (cm) from the lamp, and Z is the raw water of the ultraviolet light. Or the distance (cm) which permeate | transmits the inside of treated water is meant.

  The controller 14 inputs the measured value of the ultraviolet transmittance from the raw water ultraviolet transmittance meter 16 and the precipitated water ultraviolet transmittance meter 18.

The performance of algicide and sterilization (disinfection) by ultraviolet irradiation by the front-stage ultraviolet irradiation apparatus 5 and the rear-stage ultraviolet irradiation apparatus 10 is determined by the amount of ultraviolet rays based on the illuminance and time received by the microorganisms contained in the raw water or treated water passing through the pipe. . Generally, the amount of ultraviolet rays is defined by the following formula (2).

Here, Dose means the amount of ultraviolet rays (mJ / cm ² ), I means the illuminance of ultraviolet rays (mW / cm ² ), and t means the irradiation time (s).

  Further, the amount of ultraviolet rays necessary for killing or inactivating microorganisms to be treated (depriving fertility or depriving infectivity in the case of pathogenic microorganisms) generally varies depending on the type of microorganism. Therefore, it is necessary to consider the capabilities of the ultraviolet irradiation devices 5 and 10 according to the type of microorganism to be treated.

(Control of the front UV irradiation device 5)
In the present embodiment, the pre-stage ultraviolet irradiation device 5 is installed in the pre-stage process, which is the pre-stage of the agglomeration / sedimentation basin 3, and therefore is effective as a countermeasure against algae in addition to pathogenic microorganisms that survive in the raw water. is there. Therefore, the controller 14 controls the output of the ultraviolet lamp of the pre-stage ultraviolet irradiation device 5 in order to obtain irradiation with the amount of ultraviolet rays necessary for killing or inactivating a plurality of pathogenic microorganisms and algae.

  The controller 14 considers the measured value by the raw water ultraviolet transmittance meter 16, the measured value by the raw water flow meter 4, the arrangement of the ultraviolet lamp in the previous stage ultraviolet irradiation device 5, and the flow state of the raw water that changes depending on the internal structure and flow rate. The output of the ultraviolet lamp of the pre-stage ultraviolet irradiation device 5 is controlled using an arithmetic expression such as the aforementioned arithmetic expressions (1) to (2). Specifically, the controller 14 calculates the necessary UV output value in accordance with the UV transmittance and flow rate change by an arithmetic expression, and supplies the power supplied from the UV lamp power supply 13a to the UV lamp in the previous UV irradiation device 5. Control.

  On the other hand, if the controller 14 determines that the ultraviolet transmittance of the raw water is sufficiently higher than the reference value based on the measurement value from the raw water ultraviolet transmittance meter 16, the ultraviolet lamp of the rear ultraviolet irradiation device 10 is determined. The control is performed to reduce the output to the lower limit value or stop the operation.

  That is, when the ultraviolet transmittance of the raw water is high, only the pre-stage ultraviolet irradiation device 5 can exert sufficient algicidal and sterilizing (disinfection) capability. Consumption can be saved. In this case, from the viewpoint of the characteristics of the ultraviolet lamp, a steady waiting time is required to stably output the ultraviolet light after it is turned on, so that the output reduction operation is performed rather than stopping the operation of the subsequent ultraviolet irradiation device 10. Is preferred.

  On the other hand, the ultraviolet transmittance is affected by suspended matter, turbidity, and soluble organic matter in the raw water. For this reason, when the raw water turbidity increases due to rain or the like, the ultraviolet transmittance is greatly reduced. In such a case, the controller 14 performs control to stop the operation of the front-stage ultraviolet irradiation device 5 or to reduce the output of the ultraviolet lamp to the lower limit value. This is because, when the ultraviolet transmittance is greatly reduced, a necessary amount of ultraviolet rays may not be obtained even if irradiation is performed with the maximum capacity of the front-stage ultraviolet irradiation device 5. This is because there is a high possibility of being wasted.

  In this case, the controller 14 controls to switch the flow path by operating the three-way valves 7a and 7b so that the raw water flows into the bypass pipe 6 in order to prevent contamination in the pipe due to accumulation of suspended matter, turbidity, and adhesion of organic matter. Execute. Furthermore, the controller 14 increases the output of the rear-stage ultraviolet irradiation device 10 from the standard value to compensate for the loss of the sterilization (disinfection) ability of the microorganisms in the front-stage process.

(Control of the latter stage UV irradiation device 10)
Next, the irradiation amount control method of the latter stage ultraviolet irradiation device 10 will be described.

  Since the post-ultraviolet irradiation device 10 is installed at the rear stage of the coagulation / sedimentation basin 3, the post-ultraviolet irradiation device 10 irradiates the precipitating water, which is treated water, with ultraviolet rays. Floats and turbidity in raw water, and algae and some pathogenic microorganisms are taken into flocs, settled and removed as sludge. However, since the organic substance dissolved in water cannot be removed in the aggregation / precipitation process, it remains as an ultraviolet absorption factor in the subsequent ultraviolet irradiation apparatus 10.

  The controller 14 controls the output of the ultraviolet lamp of the post-ultraviolet irradiation device 10 in order to obtain irradiation with the amount of ultraviolet light necessary to kill or inactivate a plurality of microorganisms remaining after the aggregation / precipitation treatment.

  The controller 14 includes an ultraviolet transmittance of the precipitated water by the precipitated water ultraviolet transmittance meter 18, a flow rate measurement value by the precipitated water flow meter 9, an ultraviolet illuminance distribution determined by the arrangement of the ultraviolet lamp in the subsequent ultraviolet irradiation device 10, and a flow path structure. The output of the ultraviolet lamp of the rear-stage ultraviolet irradiation device 10 is controlled using arithmetic expressions such as the above-described arithmetic expressions (1) to (2) in consideration of the flow state that changes depending on the flow rate. Specifically, the controller 14 calculates the necessary UV output value according to the UV transmittance and the flow rate change by an arithmetic expression, and supplies the power supplied from the UV lamp power supply 13b to the UV lamp in the subsequent UV irradiation device 10. Control.

  In short, the system according to the present embodiment is configured to control and execute the ultraviolet irradiation process by the preceding ultraviolet irradiation device 5 in the previous process and the ultraviolet irradiation process by the subsequent ultraviolet irradiation apparatus 10 in the subsequent process. Therefore, inactivate and detoxify microorganisms including algae by the ultraviolet irradiation effect in the previous stage, and kill or inactivate the remaining microorganisms after aggregation / precipitation treatment by the ultraviolet irradiation effect in the subsequent stage Can be realized.

  Thereby, especially in water purification processes, such as waterworks, the effect of ultraviolet irradiation can be demonstrated, and algae countermeasures and sterilization (disinfection) treatment of pathogenic bacteria can be performed safely and reliably. Moreover, the amount of the chlorine agent that has been conventionally injected in the water purification treatment process can be greatly reduced in the system of this embodiment. Thereby, generation | occurrence | production of harmful by-products, such as a trihattomethane produced | generated in the process of disinfection by a chlorine agent, can be suppressed, and the expense concerning the chlorine agent injection | pouring can be saved.

(Second Embodiment)
FIG. 2 is a block diagram illustrating a main part of the water treatment system according to the second embodiment.

  The system of this embodiment has a raw water turbidity meter 21 and a raw water fluorescence analyzer 23 as the raw water ultraviolet transmittance measuring device, and a precipitated water fluorescence analyzer 24 as the precipitated water ultraviolet transmittance measuring device. . In addition, about the component same as the system of 1st Embodiment shown in FIG. 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the system of the present embodiment, the controller 14 inputs the turbidity of raw water measured by the raw water turbidimeter 21 and the fluorescence intensity of raw water measured by the raw water fluorescence analyzer 23. Further, the controller 14 inputs the fluorescence intensity of the precipitation water measured by the precipitation water fluorescence analyzer 24.

  The raw water turbidity meter 21 is connected to the raw water sampling pipe 15 and measures the turbidity of the raw water sample sampled by the raw water sampling pipe 15 from a pipe connecting the landing well 2 and the preceding ultraviolet irradiation device 5. The raw water fluorescence analyzer 23 is connected to the raw water sampling pipe 15 and measures the fluorescence intensity of the raw water sample collected through the filtering device 22.

  On the other hand, the precipitated water fluorescence analyzer 24 is connected to the precipitated water sampling pipe 17, and the precipitated water sampled by the precipitated water sampling pipe 17 from the pipe between the flocculation / sedimentation basin 3 and the subsequent ultraviolet irradiation device 10. Measure the fluorescence intensity of the sample.

  Here, the filtration device 22 arranged in the previous stage of the raw water fluorescence analyzer 23 is for removing turbidity in the raw water. In the raw water fluorescence analyzer 23, it is necessary to exclude turbidity in order to accurately measure the dissolved organic matter in the raw water. On the other hand, since the sedimentation water measured by the sedimentation water fluorescence analyzer 24 is aggregated and turbidity is removed in the sedimentation basin 3, a filtering device is not necessary.

(Operational effects of the second embodiment)
Hereinafter, the function and effect of this embodiment will be described with reference to FIGS. 3 to 5 together with FIG.

  In general, when ultraviolet light passes through water, it is attenuated by absorption and scattering by turbid substances such as particles floating in water, absorption by dissolved organic matter, and the like. Thereby, ultraviolet-ray intensity falls as it leaves | separates from an irradiation surface. The ultraviolet transmittance (%) represents the ratio of ultraviolet rays that are transmitted through an interval of 1 cm. As a device for measuring the ultraviolet transmittance, there are ultraviolet transmittance meters 16 and 18 as shown in FIG.

  However, a general ultraviolet transmittance meter has a configuration in which sample water is put in a standard cell of quartz glass and measured in batch, or sample water is circulated in the quartz glass cell and measured in real time. In batch measurement, it cannot be used as a control index for UV lamp output. In addition, the configuration in which sample water is circulated has a problem that measurement cannot be performed correctly due to contamination on the surface of the quartz glass cell.

  The system of the present embodiment is configured to estimate the ultraviolet transmittance based on the measurement results of the turbidity of raw water and the concentration of soluble organic matter without using a general ultraviolet transmittance meter.

  The ultraviolet transmittance is composed of an attenuation due to absorption and scattering due to turbid substances floating in water, and an attenuation due to absorption of organic substances dissolved in water. Therefore, the ultraviolet transmittance can be estimated by measuring the turbidity of raw water and the concentration of soluble organic matter.

FIG. 3 is a diagram showing the relationship between the turbidity of raw water and the ultraviolet transmittance when the influence of only absorption and scattering due to turbid components is considered. As shown in FIG. 3, turbidity and ultraviolet transmittance have a correlation, and the relationship represented by the following formula (3) is established.

Here, T _tu means ultraviolet absorption (%) when ultraviolet ray absorption and scattering substances are only turbidity, and tu means turbidity (degree).

In addition, there is ultraviolet absorbance as an index indicating absorption by soluble organic substances in water. The relationship between the ultraviolet absorbance and the ultraviolet transmittance is defined by the following formula (4).

Here, alpha _oc means an ultraviolet absorbance, T _oc means ultraviolet transmittance in the case of considering only absorption by soluble organic substances (%). Therefore, the ultraviolet transmittance can be determined by measuring the ultraviolet absorbance.

  The controller 14 of the present embodiment calculates the ultraviolet absorbance by inputting the fluorescence intensity of the raw water measured by the raw water fluorescence analyzer 23, and estimates the soluble organic substance concentration in the raw water from the ultraviolet absorbance (see FIG. 4). reference).

  FIG. 4 is a diagram showing the results of measuring the relationship between the fluorescence intensity at a fluorescence wavelength of 425 nm generated in response to the excitation wavelength of 345 nm and the ultraviolet absorbance using river water. As shown in FIG. 4, there is a linear correlation between fluorescence intensity (excitation wavelength: 345 nm, fluorescence wavelength: 425 nm) and ultraviolet absorbance (wavelength: 253.7 nm).

In addition, the relationship between the dissolved organic carbon concentration (DOC), which is an index of the soluble organic matter concentration at this time, and the fluorescence intensity is confirmed to have a very strong correlation as shown in FIG. Has been. From this, the fluorescence intensity is measured by the raw water fluorescence analyzer 23, and from the relationship between FIG. 4 and the above equation (4), as shown in the following equation (5), the ultraviolet transmittance T _oc (absorption by the soluble organic matter) Can be calculated).

  Here, c means a coefficient, and FL means fluorescence intensity.

From the above, the total ultraviolet transmittance T considering the absorption and scattering by the suspended matter in the raw water and the dissolved organic matter can be obtained from the following formula (6).

  The controller 14 uses the turbidity of the raw water measured by the raw water turbidimeter 21 and the fluorescence intensity measured by the raw water fluorescence analyzer 23 to calculate the ultraviolet transmittance of the raw water. And as demonstrated in the above-mentioned 1st Embodiment, the controller 14 controls the output of the ultraviolet lamp of the pre-stage ultraviolet irradiation device 5 based on the ultraviolet transmittance of raw | natural water. Thereby, it becomes possible to realize complete algae algae killing and sterilization (disinfection) of pathogenic microorganisms from raw water by supplying appropriate power without waste to the pre-stage ultraviolet irradiation device 5.

  Further, as in the first embodiment described above, the ultraviolet transmittance is affected by suspended matter, turbidity, and soluble organic matter in the raw water. For this reason, when the raw water turbidity increases due to rain or the like, the ultraviolet transmittance is greatly reduced. In such a case, the controller 14 performs control to stop the operation of the front-stage ultraviolet irradiation device 5 or to reduce the output of the ultraviolet lamp to the lower limit value. In this case, the controller 14 controls to switch the flow path by operating the three-way valves 7a and 7b so that the raw water flows into the bypass pipe 6 in order to prevent contamination in the pipe due to accumulation of suspended matter, turbidity, and adhesion of organic matter. Execute. Furthermore, the controller 14 increases the output of the rear-stage ultraviolet irradiation device 10 from the standard value to compensate for the loss of the sterilization (disinfection) ability of the microorganisms in the front-stage process.

  Next, the control method of the latter stage ultraviolet irradiation apparatus 10 of this embodiment is demonstrated.

  Since the post-ultraviolet irradiation device 10 is installed at the rear stage of the coagulation / sedimentation basin 3, the post-ultraviolet irradiation device 10 irradiates the precipitating water, which is treated water, with ultraviolet rays. In this case, since the turbidity in the treated water is removed from the treated water, the controller 14 transmits UV light of the precipitated water based on the fluorescence intensity measured by the precipitated water fluorescence analyzer 24 based on the relationship of the equation (5). The rate can be calculated.

  Therefore, the controller 14 controls the output of the ultraviolet lamp based on the ultraviolet transmittance of the precipitated water and the flow rate measured by the precipitated water flow meter 9 so that the necessary amount of ultraviolet rays in the subsequent ultraviolet irradiation device 10 can be secured. . For this reason, wasteful power consumption can be prevented as well as surely disinfecting pathogenic microorganisms.

(Third embodiment)
FIG. 7 is a block diagram illustrating a main part of a water treatment system according to the third embodiment.

  The system of this embodiment relates to ultraviolet irradiation control using ultraviolet illuminance meters 19 and 20 installed in the front-stage ultraviolet irradiation apparatus 5 and the rear-stage ultraviolet irradiation apparatus 10, respectively. In addition, about the component same as the system of 1st Embodiment shown in FIG. 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  FIG. 6 is a diagram showing an internal configuration of the front-stage ultraviolet irradiation device 5 used in the system of the present embodiment, and the ultraviolet lamp 27 is arranged so as to be perpendicular to the direction of the treated water flow. An example of the case is shown. This internal configuration is the same even in the case of the post-ultraviolet irradiation device 10.

  In the system of the present embodiment, as shown in FIG. 7, ultraviolet illuminance meters 19 and 20 are provided in each of the front ultraviolet irradiation device 5 and the rear ultraviolet irradiation device 10. The controller 14 inputs the measurement results from the ultraviolet illuminance meters 19 and 20.

  Here, as shown in FIG. 6, the front ultraviolet irradiation device 5 and the rear ultraviolet irradiation device 10 incorporate a plurality of ultraviolet lamps 27, and a quartz glass ultraviolet lamp protective tube 28 for protecting each ultraviolet lamp 27. Have Further, the front-stage ultraviolet irradiation device 5 and the rear-stage ultraviolet irradiation device 10 have a cleaning scrubbing member 29 for cleaning the protective tube 28. The cleaning scrubbing member 29 is driven by a cleaning drive device 25 (however, the cleaning drive device 26 in the latter stage ultraviolet irradiation device 10). The cleaning drive devices 25 and 26 are controlled by the controller 14.

  As will be described later, the controller 14 of the present embodiment controls the output of the ultraviolet lamps 27 of the ultraviolet irradiation devices 5 and 10 using the ultraviolet illuminance meters 19 and 20, and operates the cleaning member 29 for cleaning the ultraviolet lamp protection tube 28. It is configured to execute control and performance monitoring of the ultraviolet lamp 27. This will be specifically described below.

(UV lamp 27 output control)
The controller 14 controls the output of the ultraviolet lamp 27 incorporated in the front-stage ultraviolet irradiation device 5 by the control method described in the first or second embodiment. Here, the controller 14 inputs the measurement value from the ultraviolet illuminance meter 19 so as to constantly monitor the ultraviolet illuminance in the preceding ultraviolet irradiation device 5.

On the other hand, the target amount of ultraviolet rays Dose _targ necessary for killing or inactivating the target microorganism (algae or pathogen) is preset (stored) in the controller 14. Further, the controller 14 includes an equation (7) for calculating the residence time t from the measured value F _R of the raw water flow meter 4 and the flow path structure of the previous-stage ultraviolet irradiation device 5, and the ultraviolet light amount target value Dose _targ. An arithmetic expression (8) for calculating the ultraviolet illuminance target value I _targ at the installation position of the ultraviolet illuminance meter 19 from the residence time t is set.

Here, F _R is measured by the raw water flow meter ^(m 3 / s), S is a representative flow path cross-sectional area ^(m 2), L is a representative flow path length (m).

Here, C _t is a correction coefficient, and is determined by the relationship of Expression (9) based on the positional relation constant K _t between the ultraviolet illuminance meter 19 and the ultraviolet lamp 27 and the measured value T _R by the raw water ultraviolet transmittance meter 16.

The controller 14 compares “I _meas ” and “I _targ ” using the arithmetic expression (8) and the measurement value I _meas measured by the ultraviolet illuminance meter 19, and the comparison result is “I _meas <I _targ ”. In this case, control is performed so that the output of the ultraviolet lamp 27 is increased. When the comparison result is “I _meas > I _targ ”, the output of the ultraviolet lamp 27 is controlled to decrease.

  The controller 14 also performs similar output control for the ultraviolet lamp 27 of the rear-stage ultraviolet irradiation device 10.

(Cleaning control of UV lamp protection tube and irradiation performance monitoring of UV lamp)
The controller 14 of the present embodiment includes an arithmetic expression (10) for calculating the ultraviolet illuminance I ₀ on the surface of the ultraviolet lamp protection tube 28 and the measured value I _meas by the ultraviolet illuminance meter 19 when the ultraviolet lamp 27 is output. Is set to an arithmetic expression (11) for calculating the ultraviolet illuminance I _m0 on the surface of the ultraviolet lamp protection tube 28 and an allowable value ΔI _f of the difference “ΔI = I ₀ −I _m0 ” between I ₀ and I _m0. ing.

Here, W means the ultraviolet lamp steady input power (W). Further, w means an ultraviolet lamp input power set value (W), and η _UV means an ultraviolet output efficiency (%).

Here, K _m0 is a constant determined by the positional relationship between the ultraviolet lamp 27 and the ultraviolet illuminance meter 19. I _meas denotes the value measured by ultraviolet illuminance meter 19 ^{(mW / cm 2), T} R denotes a raw water ultraviolet transmittance (%).

The controller 14 compares the difference “difference ΔI = I ₀ −I _m0 ” and “ΔI _f ” between I ₀ and I _m0 calculated from the arithmetic expressions (10) and (11), and the comparison result is “ΔI ≧ In the case of “ΔI _f ”, the cleaning driving device 25 is controlled so that the cleaning scrubber 29 of the UV lamp protection tube 28 is operated.

  Next, the operation of monitoring the irradiation performance of the ultraviolet lamp will be described.

  Since the ultraviolet ray generation efficiency of the ultraviolet lamp 27 decreases with time according to individual lamp characteristics, it is necessary to replace it periodically. Therefore, when it is determined that the ultraviolet lamp 27 has deteriorated beyond an allowable range, the controller 14 performs a control to perform display output for prompting replacement of the ultraviolet lamp 27 from a display device or the like.

Specifically, the controller 14 is set with an initial surface illuminance value I _ini of the ultraviolet lamp protection tube 28 and an allowable value ΔI _{ini for the} lamp performance degradation. The controller 14 calculates the surface ultraviolet illuminance I _m0 of the ultraviolet lamp protective tube 28 from the measured value I _meas by the ultraviolet lamp illuminance meter 19 immediately after the operation of the cleaning member 29 for cleaning the ultraviolet lamp protective tube 28 according to the above equation (11). calculate. The controller 14 compares the calculated value with a preset difference “ΔIc = I _ini −I _m0 ” between the initial illuminances I _ini and an allowable value ΔI _ini of the lamp performance degradation, and the comparison result is “ΔI _c In the case of “> ΔI _ini ”, a display output that prompts replacement of the ultraviolet lamp 27 is executed.

Immediately after the replacement of the ultraviolet lamp 27, “ΔI _c = 0” must be obtained. However, since the initial performance of the ultraviolet lamp 27 is actually varied, the allowable performance value of the new lamp is set as ΔI _{ini, 0} . . If the comparison result immediately after replacing the ultraviolet lamp 27 is “ΔI _c > ΔI _{ini, 0} ”, the controller 14 issues an alarm for other device failures such as abnormality of the protective tube 28 and deterioration of the cleaning brush 29. A display output that prompts comprehensive maintenance such as replacement of the protective tube 28 and replacement of the cleaning brush 29 is executed.

  The controller 14 also performs similar monitoring control for the ultraviolet lamp 27 of the rear-stage ultraviolet irradiation device 10.

  In short, in the system of the present embodiment, it is determined whether the amount of ultraviolet rays is excessive or insufficient based on the measured values by the ultraviolet illuminance meters 19 and 20 provided in the front-stage ultraviolet irradiation device 5 and the rear-stage ultraviolet irradiation device 10. The output of the ultraviolet lamp 27 can be corrected and controlled by feedback. Furthermore, by monitoring the state of contamination on the surface of the UV lamp protection tube 28 and monitoring the decrease in UV generation efficiency of the UV lamp 27, operation control of the cleaning member 29 for the UV lamp protection tube 28 and lamp maintenance are performed. Can provide support. Thereby, the useful water treatment system which can maintain the stable ultraviolet irradiation performance and can perform maintenance of the ultraviolet irradiation apparatuses 5 and 10 automatically can be realized.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

The block diagram which shows the principal part of the water treatment system regarding the 1st Embodiment of this invention. The block diagram which shows the principal part of the water treatment system regarding 2nd Embodiment. The figure which shows the relationship between the turbidity and ultraviolet-ray transmittance regarding 2nd Embodiment. The figure which shows the relationship between the fluorescence intensity regarding 2nd Embodiment, and ultraviolet-ray light absorbency. The figure which shows the relationship between the fluorescence intensity regarding 2nd Embodiment, and soluble organic carbon concentration. The figure which shows the internal structure of the front | former stage ultraviolet irradiation device regarding 3rd Embodiment. The block diagram which shows the principal part of the water treatment system regarding 3rd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sand basin, 2 ... Landing well, 3 ... Coagulation / sedimentation basin, 4 ... Raw water flow meter,
5 ... Pre-stage UV irradiation device, 6 ... Bypass piping, 7a ... Inlet three-way valve, 7b ... Outlet three-way valve,
8 ... Filtration pond, 9 ... Precipitated water flow meter, 10 ... Subsequent ultraviolet irradiation device, 11 ... Bypass piping,
12a ... Inlet three-way valve, 12b ... Outlet three-way valve, 13a, 13b ... UV lamp power supply,
14 ... Clean water treatment monitoring and control device (controller), 15 ... Raw water sampling pipe,
16 ... Raw water ultraviolet transmittance meter, 17 ... Precipitation water sampling pipe, 18 ... Precipitation water transmittance meter,
19, 20 ... UV illuminance meter, 21 ... Raw water turbidity meter, 22 ... Filtration device,
23 ... Raw water fluorescence analyzer, 24 ... Precipitation water fluorescence analyzer,
25, 26 ... Driving device for cleaning the UV lamp protective tube, 27 ... UV lamp,
28 ... UV lamp protective tube, 29 ... Washing member for cleaning.

Claims (3)

In a water treatment system that performs water purification treatment by ultraviolet irradiation,
A first ultraviolet irradiation device for irradiating ultraviolet rays in the raw water coagulation / sedimentation treatment step as a pre-stage of the water purification treatment step;
In the subsequent process of the water purification process, a second ultraviolet irradiation device for irradiating the treated water of the previous process with ultraviolet rays,
Control means for controlling the first and second ultraviolet irradiation devices ;
A first ultraviolet illuminance meter for measuring the ultraviolet illuminance in the first ultraviolet irradiation device,
The control means includes
A formula for calculating an ultraviolet ray illuminance target value based on an ultraviolet ray amount target value based on the ultraviolet ray irradiation effect, a raw water flow rate measurement value, a residence time, and the ultraviolet ray amount target value is set,
Compare the measured value of the first ultraviolet illuminance meter with the ultraviolet illuminance target value calculated by the calculation formula,
When the comparison result is larger than the ultraviolet illuminance target value, control to increase the output of the ultraviolet lamp in the first ultraviolet irradiation device,
When the comparison result shows that the ultraviolet illuminance target value is smaller , the water treatment system is controlled to reduce the output of the ultraviolet lamp in the first ultraviolet irradiation device . The second ultraviolet irradiation device is:
The ultraviolet ray is irradiated to the treated water between the agglomeration / sedimentation basin in the agglomeration / sedimentation treatment step and the filtration basin included in the subsequent step. The described water treatment system. A precipitating water ultraviolet transmittance meter for measuring the ultraviolet transmittance of the precipitating water which is the treated water in the subsequent step;
The said control means controls the output of the ultraviolet lamp incorporated in the said 2nd ultraviolet irradiation device based on the measurement result of the said precipitation water ultraviolet-ray-transmittance meter, The Claim 1 or Claim 2 characterized by the above-mentioned. The water treatment system according to any one of claims.

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