JP2005324124A - Ozone gas injection control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ozone gas injection control system which can control generation of energy useless for ozone gas generation, and control generation of a bromate ion by preventing dissolved ozone concentration from going to excess, and keep the proper quality of ozone-treated water. <P>SOLUTION: An ozone reaction tank 3 comprises a plurality of ozone contact tanks 3a, 3b, 3c, 3d into which ozone is injected from an ozone gas injection device 7. The plurality of the ozone contact tanks 3a, 3b, 3c, 3d are divided into at least two groups G1, G2. An ozone gas injection control device 10 controls the ozone gas injection device 7 based on the fluorescence intensities measured by fluorescence intensity analyzers 6a, 6b, 6c to adjust the injection rate of ozone gas injected into each of the ozone contact tanks 3a, 3b, 3c, 3d for the groups G1, G2 respectively. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ozone gas injection control system installed in water treatment facilities such as water purification treatment, sewage treatment, industrial wastewater treatment, and food wastewater treatment.

  In water treatment facilities, a method for ozone treatment of water to be treated such as raw water using ozone gas having a strong oxidizing power is widely known.

  By performing such ozone treatment, many harmful substances (hereinafter also referred to as “reactive substances”) dissolved in the water to be treated can be oxidized. Specifically, ozone treatment can be used to sterilize and disinfect bacteria and viruses, kill algae, decolorize as a countermeasure against coloring components, deodorize as a countermeasure against odorants, oxidative decomposition of organic and inorganic substances, It is used for various purposes such as degradability.

For example, a lot of humic substances, which are decomposition products of animal and plant bodies, are dissolved in the raw water sent from the coagulation sedimentation pond. This humic substance is a residue obtained by decomposing animal and plant bodies by microorganisms, and is the above-mentioned hardly decomposable organic substance, which is colored and has many unsaturated bonds that cause this coloring in the molecule. ing.
In the ozone reaction, such humic substances react with ozone to be easily decomposable organic matter.

  As a method for injecting ozone gas in the ozone treatment, a method of injecting ozone gas with a constant flow rate to the treated water (hereinafter referred to as “ozone injection rate constant control”), Generally, a method of performing feedback control (hereinafter referred to as “dissolved ozone concentration constant control”) so that the concentration of dissolved ozone remaining after reacting with a reactant in the treated water becomes constant is used.

  However, the constant control of the ozone injection rate is a method of continuously injecting ozone gas at a preset ozone injection rate. Therefore, when the properties of the water to be treated change, the ozone injection rate may be excessive or insufficient. Specifically, when the property of the water to be treated is changed and the ozone injection rate becomes insufficient, the quality of the ozone treated water is deteriorated. On the other hand, when the property of the water to be treated is changed and the ozone injection rate becomes excessive, extra energy for generating ozone gas is generated.

Further, in the constant dissolved ozone concentration control, it is necessary to measure a larger amount of ozone as the dissolved ozone concentration than the amount of ozone actually used for the reaction with the reactant in the water to be treated. As a result, there is a problem that ozone gas must be injected in excess of the amount of ozone required for the ozone reaction.
In water treatment and the like, since bromate ions, which are by-products of ozone treatment, are added to the water quality standards for tap water from 2004, it is necessary to avoid excessive injection of ozone gas. The control range of dissolved ozone is required to be smaller than the lower limit of the detection value of the dissolved ozone concentration meter.

Furthermore, there are many unstable factors in ozone treatment by constant control of dissolved ozone concentration.
In other words, ozone decomposes and disappears by promoting self-decomposition by heat and humidity. Further, the dissolved ozone accelerates the aforementioned self-decomposition depending on the pH and temperature of the dissolved water, and a large difference appears in the stability. On the other hand, it is known that dissolved ozone hardly decomposes in a closed container.
Thus, it is not appropriate to control the generation of ozone with large power consumption by measuring the concentration of dissolved ozone with instability and uncertainty.

  As described above, the method of controlling the ozone injection rate by the constant control of the dissolved ozone concentration is unstable and is not appropriate.

  In the above ozone treatment, the absorbance method (E260) utilizing the properties relating to the absorption of ultraviolet rays is generally used as an index for measuring the concentration of organic substances in water. This absorbance method is a method for obtaining a difference between incident light and transmitted light and is a simple measurement method, but has a problem that an error becomes large between a low concentration and a high concentration. In the future, there is a movement to exclude the absorbance method.

  On the other hand, according to Patent Document 1, for example, the fluorescence intensity of ozone-treated water is measured, a target ozone injection rate such that the fluorescence intensity falls within a certain range is obtained, and a dissolved ozone concentration is obtained from the target ozone injection rate. There is known an ozone treatment apparatus provided with a constant dissolved ozone concentration control means for controlling the amount of ozone generated so as to fall within a target dissolved ozone concentration range.

JP-A-4-225895

  As described above, the ozone treatment apparatus disclosed in Patent Document 1 described above measures the fluorescence intensity of ozone-treated water, obtains a target ozone injection rate such that the fluorescence intensity falls within a certain range, and the dissolved ozone concentration is Dissolved ozone concentration constant control means for controlling the amount of ozone generated so as to fall within the target dissolved ozone concentration range obtained from the target ozone injection rate is provided. In such an ozone treatment apparatus, there is a problem that the specific contents of the ozone reaction on the water to be treated are not reflected at all.

The ozone reaction with respect to to-be-processed water is demonstrated concretely using FIG. FIG. 14 is a graph showing the correlation between the ozone injection rate, the relative fluorescence intensity of ozone-treated water, and the dissolved ozone concentration when ozone gas is injected into the water to be treated in an ozone injection system used for water purification and the like. is there.
In FIG. 14, the horizontal axis of the graph is the ozone injection rate (mg / L), the solid line portion in the graph is the relative fluorescence intensity of the ozone-treated water, and the value is displayed on the vertical axis on the left side of the graph. The dotted line in the figure is the dissolved ozone concentration (mg / L), and the value is displayed on the right side of the graph.

  As shown in FIG. 14, when the ozone injection rate is low, for example, 0.8 mg / L or less, the relative fluorescence intensity of the ozone-treated water is greatly reduced as the ozone injection rate is increased. In this case, the dissolved ozone concentration is 0.05 mg / L or less, which is a measurement region that is difficult to detect with a dissolved ozone concentration meter.

  On the other hand, when the ozone injection rate is high, for example, exceeding 1 mg / L, the relative fluorescence intensity of the ozone-treated water hardly decreases even if the ozone injection rate increases. On the other hand, the dissolved ozone concentration greatly increases as the ozone injection rate increases.

  That is, according to the graph of FIG. 14, the water to be treated sent from the coagulation sedimentation basin has a slow decomposition reaction with respect to the injected ozone gas, for example, a reactive substance such as humic substances having a fast decomposition reaction with the injected ozone gas. It turns out that the reactive substance which has a property is mixed. In particular, ozone treatment of raw tap water requires effective oxidation removal of the former humic substances, and fluorescence analysis can selectively detect humic substances with high sensitivity.

  For this reason, for reactants that have a fast decomposition reaction to the injected ozone gas, the required amount of ozone gas is reacted at a time to reduce the amount of the reactant, while the decomposition reaction to the injected ozone gas. For reactants that have slow properties, ozone gas that gently reduces the amount of reactants that react slowly while suppressing the excess ozone concentration by reacting with minimal ozone gas for a long period of time It is preferable to perform injection control.

  However, in the ozone treatment apparatus shown in Patent Document 1, the ozone reaction tank is simply divided into a plurality of components, and the reactant has a fast decomposition reaction in the water to be treated flowing from the coagulation sedimentation basin. No mention is made of performing an ozone reaction at different ozone injection rates corresponding to the reaction materials having a slow decomposition reaction property. Further, in the control of the ozone injection rate described in Patent Document 1, the specific contents of the ozone reaction are not reflected at all.

  The present invention has been made in consideration of such points, and can suppress the generation of useless energy for generating ozone gas, and also suppress the excessive concentration of dissolved ozone. Therefore, an object of the present invention is to provide an ozone gas injection control system capable of suppressing the generation of bromate ions and maintaining the quality of the ozone treated water appropriately.

  The present invention is directed to an ozone reaction tank comprising a plurality of ozone contact tanks each having an ozone inlet, and an ozone gas from the ozone inlet into each ozone contact tank. Are provided in the introduction line and / or one of the ozone contact tanks, and the treated water and each ozone contact in the introduction line. Each ozone contact is controlled by controlling the ozone gas injection device based on the fluorescence intensity measured by the fluorescence intensity analyzer and the fluorescence intensity analyzer that measures at least one fluorescence intensity of each ozone treated water in the tank An ozone gas injection control device for adjusting an injection rate of ozone gas injected into the tank, and the plurality of ozone contact tanks include at least two groups. The ozone gas injection control device controls the ozone gas injection device based on the fluorescence intensity measured by the fluorescence intensity analyzer, and determines the injection rate of the ozone gas injected into each ozone contact tank. The ozone gas injection control system is characterized in that it is adjusted for each group.

The present invention is directed to an ozone reaction tank comprising a plurality of ozone contact tanks each having an ozone inlet, and an ozone gas from the ozone inlet into each ozone contact tank. Are provided in at least two ozone gas injection devices for obtaining the ozone treated water, the introduction line and / or one of the ozone contact tanks, and the treated water in the introduction line and Each ozone gas injection device is controlled based on a fluorescence intensity analyzer that measures at least one fluorescence intensity of each ozone treated water in each ozone contact tank and the fluorescence intensity measured by the fluorescence intensity analyzer. And an ozone gas injection control device that adjusts the injection rate of ozone gas injected into each ozone contact tank. At the same time, each ozone gas injection device is installed to correspond to a group of ozone contact tanks, and the ozone gas injection control device is based on the fluorescence intensity measured by the fluorescence intensity analyzer. The ozone gas injection control system is characterized in that the ozone gas injection device corresponding to is controlled to adjust the injection rate of ozone gas injected into each ozone contact tank for each group.
In such an ozone gas injection control system, one ozone gas injection device and the ozone contact tank of the group corresponding to this ozone gas injection device are connected by a single pipe, and the other ozone gas injection device and this ozone gas injection device are connected. It is preferable that the ozone contact tank of the group corresponding to the apparatus is connected by another pipe, and the one pipe and the other pipe are connected to each other via an on-off valve.

  In the ozone gas injection control system of the present invention, it is preferable that an additional fluorescence intensity analyzer for measuring the fluorescence intensity of the ozone-treated water flowing out of the ozone reaction tank is provided on the downstream side of the ozone reaction tank.

  In the ozone gas injection control system of the present invention, between the ozone contact tank and the fluorescence intensity analyzer, an analysis introduction line for guiding the ozone treated water in the plurality of ozone contact tanks to the fluorescence intensity analyzer is installed. Is preferred.

  In the ozone gas injection control system of the present invention, it is preferable that a dissolved ozone concentration meter for measuring the dissolved ozone concentration of the ozone-treated water in the ozone contact tank is provided in the ozone contact tank of the downstream group.

  In the ozone gas injection control system of the present invention, at least any one of the water to be treated in the introduction line and / or each of the ozone contact tanks in each ozone contact tank is provided in the introduction line and / or any of the ozone contact tanks. The apparatus further comprises a water quality measuring device for measuring the water temperature and / or pH, and the ozone gas injection control device applies at least one of the fluorescence intensity measured by the fluorescence intensity analyzer, the water temperature measured by the water quality measuring device, and the pH. Based on this, it is preferable to correct the injection control of the ozone gas for each group.

  In the ozone gas injection control system of the present invention, the ozone gas injection control device is configured so that each of the ozone gas injection control devices is based on at least one of the fluorescence intensity measured by the fluorescence intensity analyzer, the water temperature measured by the water quality measuring instrument, and the pH. It is preferable to determine the correction timing of the ozone gas injection control for each group.

  In the ozone gas injection control system of the present invention, a fluorescence intensity analyzer is provided in each ozone contact tank, and in the control by the ozone gas injection control device, the ozone gas injection control for each group is performed in advance by a plurality of fluorescence intensity analyses. It is preferable to correct based on the fluorescence intensity measured by the meter.

  In the ozone gas injection control system of the present invention, the fluorescence intensity analyzer irradiates water to be inspected with light having an excitation wavelength of 320 to 370 nm, and measures a fluorescence wavelength of 400 to 450 nm in the fluorescence spectrum. Therefore, it is preferable to measure the fluorescence intensity of water to be inspected.

  In the ozone gas injection control system of the present invention, the fluorescence intensity analyzer is provided in each of the introduction line and at least one ozone contact tank, and the ozone gas injection control device is configured to detect the fluorescence intensity from the fluorescence intensity analyzer in the introduction line. It is preferable to control the ozone gas injection device based on the fluorescence intensity change rate obtained from the fluorescence intensity from the fluorescence intensity analyzer of the ozone contact tank.

  According to the ozone gas injection control system of the present invention, the plurality of ozone contact tanks in the ozone reaction tank are divided into at least two groups, and the injection rate of ozone gas injected into each ozone contact tank is controlled for each group. be able to. Therefore, it is possible to perform ozone treatment for each group corresponding to a reactive substance having a fast decomposition property and a reactive substance having a slow decomposition reaction with respect to the injected ozone gas in the water to be treated. By injecting the minimum ozone gas corresponding to each reactant. For this reason, generation | occurrence | production of the useless energy for producing | generating ozone gas can be suppressed. And since it can suppress that dissolved ozone concentration becomes excess, the production | generation of bromate ion can be suppressed and the quality of ozone treated water can be kept appropriate.

First Embodiment Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. 1 to 7 are diagrams showing a first embodiment of the present invention.

  Among these, FIG. 1 is a block diagram showing the configuration of the ozone gas injection control system according to the first embodiment of the present invention, and FIG. 2 is a graph showing the correlation between the fulvic acid concentration in water and the relative fluorescence intensity. FIG. 3 (a) shows the state of the ozone reaction with respect to the reactant having the property of fast decomposition reaction, and FIG. 3 (b) shows the state of the ozone reaction with respect to the reactant having the property of the slow decomposition reaction. FIG.

  FIG. 4 is a graph showing the correlation between the ozone injection rate when ozone gas is injected into the water to be treated, the relative fluorescence intensity of the ozone treated water, bromate ions, and the dissolved ozone concentration. It is a graph which shows the correlation with the ozone injection rate at the time of inject | pouring ozone gas with respect to to-be-processed water, the relative fluorescence intensity of ozone-treated water, and trihalomethane production ability.

  FIG. 6 is a graph showing the relationship between the time elapsed after the ozone gas was injected into the water to be treated, the relative fluorescence intensity of the water to be treated, and the dissolved ozone concentration, and FIG. It is a graph which shows the correlation of the ozone injection rate in case the relative fluorescence intensity of this changes, and the relative fluorescence intensity of ozone treated water.

  In addition, although this embodiment demonstrates the ozone gas injection | pouring control system in advanced water purification processing equipment, when processing to-be-processed water by injection | pouring of ozone gas also in other water treatment equipment etc., this embodiment is applicable. It is.

As shown in FIG. 1, in the ozone gas injection control system according to the present invention, the water to be treated introduced through the introduction line 1a sequentially flows, and a plurality of ozone contact tanks each having ozone injection ports 9a, 9b, 9c. Ozone reaction tank 3 comprising 3a, 3b, 3c, 3d, and an ozone gas injection device for injecting ozone gas into each ozone contact tank 3a, 3b, 3c to react the water to be treated and ozone gas to obtain ozone treated water 7 and fluorescence intensity analyzers 6a, 6b, 6c provided in the introduction line 1a and the ozone contact tanks 3a, 3b, 3c, 3d, and fluorescence intensity measured by the fluorescence intensity analyzers 6a, 6b, 6c. And an ozone gas injection control device 10 that controls the ozone gas injection device 7 to adjust the injection rate of ozone gas injected into the ozone contact tanks 3a, 3b, and 3c.
Among these, the ozone contact tank 3d is not provided with an ozone inlet, and the ozone contact tank 3d functions as an ozone retention tank into which ozone gas is not injected.

The fluorescence intensity analyzers 6a, 6b, and 6c are connected to the introduction line 1a and the ozone contact tanks 3a, 3b, 3c, and 3d, and the water to be treated in the introduction line 1a and the ozone contact tanks 3a, 3b, 3c, and 3d Measure the fluorescence intensity of each ozone-treated water.
An outflow line 1b is provided on the downstream side of the ozone reaction tank 3, and the ozone treated water flows out from the outflow line 1b.

  Moreover, raw water etc. are sent to the introduction line 1a as a to-be-processed water from a coagulation sedimentation basin, for example.

  By the way, each ozone contact tank 3a, 3b, 3c, 3d is divided into the 1st group G1 which consists of the ozone contact tank 3a, and the 2nd group G2 which consists of the ozone contact tanks 3b, 3c, 3d.

  In each of the ozone contact tanks 3a, 3b, 3c, and 3d, water sampling ports 4a, 4b, 4c, and 4d for collecting ozone-treated water in the tank and sending them to the fluorescence intensity analyzers 6b and 6c are provided. ing.

In the ozone contact tank 3a of the ozone reaction tank 3, when the water to be treated first comes into contact with the ozone gas injected from the ozone inlet 9a and then the water to be treated flows for 5 minutes, the water sampling port in the ozone contact tank 3a It reaches 4a.
Similarly, in the ozone contact tank 3a of the ozone reaction tank 3, when the water to be treated first comes into contact with the ozone gas injected from the ozone inlet 9a and then the water to be treated flows for 10, 15, and 20 minutes, The water sampling ports 4b, 4c, and 4d in the contact tanks 3b, 3c, and 3d are respectively reached.

  By the way, between the sampling ports 4a and 4b of the ozone contact tanks 3a and 3b and the fluorescence intensity analyzer 6b, an analysis introduction line 15b for guiding the ozone treated water in the ozone contact tanks 3a and 3b is arranged. . Further, an analytical introduction line 15c for guiding the ozone treated water in the ozone contact tanks 3c and 3d is disposed between the water sampling ports 4c and 4d of the ozone contact tanks 3c and 3d and the fluorescence intensity analyzer 6c. .

Specifically, the ozone-treated water in the ozone contact tanks 3a and 3b collected by the water sampling ports 4a and 4b is sent to the analysis introduction line 15b and merged on the downstream side of the water sampling ports 4a and 4b. Are sent to the fluorescence intensity analyzer 6b.
On the other hand, the ozone-treated water in the ozone contact tanks 3c and 3d collected by the water collection ports 4c and 4d is sent to the analysis introduction line 15c, and merges at the downstream side of the water collection ports 4c and 4d, and the fluorescence intensity It is sent to the analyzer 6c.
As shown in FIG. 1, on the downstream side of the sampling ports 4a, 4b, 4c, 4d and on the analysis introduction lines 15b, 15c before joining, as shown in FIG. 5c and 5d are provided.

The fluorescence intensity analyzer 6a continuously measures the fluorescence intensity of the water to be treated collected in the introduction line 1a.
The fluorescence intensity analyzer 6b continuously measures the fluorescence intensity of the ozone-treated water in the ozone contact tanks 3a and 3b sampled by the sampling ports 4a and 4b. The ozone-treated water in the ozone contact tanks 3a and 3b sent to the fluorescence intensity analyzer 6b can be freely switched by the switching valves 5a and 5b.

  Similarly, the fluorescence intensity analyzer 6c continuously measures the fluorescence intensity of the ozone-treated water in the ozone contact tanks 3c and 3d sampled by the sampling ports 4c and 4d. The ozone-treated water in the ozone contact tanks 3c and 3d sent to the fluorescence intensity analyzer 6c can be freely switched by the switching valves 5c and 5d.

  The fluorescence intensity analyzers 6a, 6b, and 6c each irradiate the water to be inspected with light having an excitation wavelength of 320 nm to 370 nm, and measure the fluorescence wavelength of 400 nm to 450 nm in the fluorescence spectrum, The fluorescence intensity of water to be inspected is measured.

  An additional fluorescence intensity analyzer may be provided to measure the fluorescence intensity of the ozone treated water that has flowed out of the ozone reaction tank 3 to the outflow line 1b.

Next, the fluorescence intensity analyzers 6a, 6b, 6c will be described in more detail.
As shown in FIG. 2, the fluorescence intensity of the water to be inspected measured by the fluorescence intensity analyzers 6a, 6b, 6c is the concentration of the fulvic acid-like organic substance existing in the water to be inspected (hereinafter referred to as “fulvoc”). It is also referred to as “acid concentration”). This fulvic acid-like organic substance will be described later. FIG. 2 is a graph showing the correlation between the fulvic acid concentration during ozone treatment and the relative fluorescence intensity, as described above, and the horizontal axis represents the fulvic acid concentration (mg / L) during ozone treatment, and the vertical axis. Indicates relative fluorescence intensity.

  The method of measuring water to be inspected by fluorescence analysis is highly sensitive to capture light emission from fulvic acid-like organic substances, and the scattering of light is inversely proportional to the fourth power of the wavelength. The error due to turbidity is smaller than the absorbance method (E260) which is an index, and continuous measurement is possible without a reagent.

  In addition, the measurement method by the absorbance method (E260) is not suitable for the measurement of ozone-treated water because dissolved ozone dissolved in water absorbs light. On the other hand, the measurement method based on the analysis of fluorescence intensity is suitable for the measurement of ozone-treated water because dissolved ozone in the ozone-treated water does not affect the measured value.

  And in the ozone contact tanks 3c and 3d in the second group G2 on the downstream side, the dissolved ozone concentration of each ozone-treated water sampled from the water sampling ports 4c and 4d in the ozone contact tanks 3c and 3d is measured. A dissolved ozone concentration meter 12 is installed.

  Further, the fluorescence intensity analyzers 6a, 6b, 6c are controlled by the ozone gas injection device 7 based on the fluorescence intensities measured by the fluorescence intensity analyzers 6a, 6b, 6c. An ozone gas injection control device 10 that adjusts the injection rate of ozone gas injected into 3c for each of the groups G1 and G2 is connected.

  On the downstream side of the ozone gas injection control system, a biological activated carbon treatment system (not shown) that performs microbial decomposition and adsorption using biological activated carbon, for example, is provided.

  Next, the operation of the present embodiment having such a configuration will be described.

  First, water to be treated such as raw water sent from a coagulating sedimentation basin, for example, flows through the introduction line 1 a into the ozone contact tank 3 a of the ozone reaction tank 3. The water to be treated that has flowed into the ozone contact tank 3a reacts with ozone injected from the ozone inlet 9a in the ozone contact tank 3a by the ozone gas injection device 7.

  In the ozone reaction tank 3, the ozone reaction water sequentially flows from the ozone contact tanks 3a to 3b, 3c, and 3d. Thereafter, the ozone reaction water further reacts with ozone gas injected from the ozone injection ports 9b and 9c by the ozone gas injection device 7 in the ozone contact tanks 3b and 3c, respectively, as in the case of the ozone contact tank 3a. .

  Thus, in each ozone contact tank 3a, 3b, 3c of the ozone reaction tank 3, by injecting ozone gas from the ozone gas injection device 7 into the water to be treated, an oxidation reaction is performed, and the hardly decomposability in the water to be treated. Organic substances can be transformed into readily decomposable organic substances.

In the course of this ozone treatment, the fluorescence intensity of the water to be treated in the introduction line 1a is measured by the fluorescence intensity analyzer 6a.
Further, the ozone-treated water sampled from the sampling ports 4a and 4b is guided to the fluorescence intensity analyzer 6b through the analysis introduction line 15b. Then, the fluorescence intensity of each ozone-treated water in the ozone contact tanks 3a and 3b is measured by the fluorescence intensity analyzer 6b.
Similarly, the ozone-treated water sampled from the sampling ports 4c and db is led to the fluorescence intensity analyzer 6c through the analysis introduction line 15c. Then, the fluorescence intensity of each ozone-treated water in the ozone contact tanks 3c and 3d is measured by the fluorescence intensity analyzer 6c.

  During this time, the ozone gas injection control device 10 controls the ozone gas injection device 7 to inject the ozone gas injection rate S1 injected into the ozone contact tank 3a of the first group G1 and the ozone contact tank 3b of the second group G2. The injection rate S2 of ozone gas injected into 3c is adjusted.

  Specifically, the ozone gas injection control device 10 performs feedforward control (hereinafter also referred to as “FF control”) based on the fluorescence intensity of the water to be treated in the introduction line 1a measured by the fluorescence intensity analyzer 6a. By adjusting the injection rate S1 of ozone gas injected into the ozone contact tank 3a in the first group G1, the injection rate S2 of ozone gas injected into the ozone contact tanks 3b and 3c in the second group G2 is similarly adjusted. adjust.

Note that the control performed by the ozone gas injection control device 10 is not limited to the FF control described above. That is, the ozone gas injection control device 10 performs feedback control based on at least one of the fluorescence intensities of the ozone-treated water in the ozone contact tanks 3a, 3b, 3c, and 3d measured by the fluorescence intensity analyzers 6b and 6c. (Hereinafter, also referred to as “FB control”) may be performed. Specifically, the ozone gas injection control device 10 adjusts each ozone injection rate so that, for example, the relative fluorescence intensity of the ozone-treated water sampled by the water sampling port 4d is 10 or less. Depends on the quality of the water to be treated.
Further, the ozone gas injection control device 10 may perform control that combines FF control and FB control, which will be described in detail later.

  Here, when the change in the quality of the water to be treated is small, it is preferable to perform the FB control with the target value of the relative fluorescence intensity as a constant value. On the other hand, when the quality of the water to be treated is large or when the ratio of the amount of inflow water from a plurality of water sources changes with time, FF control is preferably performed, and control combining FF control and FB control is performed. More preferably.

  The ozone-treated water that has flowed out of the ozone reaction tank 3 to the outflow line 1b is sent to a biological activated carbon treatment system in the subsequent stage, where the readily degradable organic matter in the ozone-treated water is microbially decomposed by the biological activated carbon, and further, by adsorption of trace chemical substances. Purified water can be obtained.

  Here, the ozone treatment for injecting ozone gas into the water to be treated in the ozone gas treatment system will be described in detail.

  Ozone treatment used for water purification treatment can change the hard-to-decompose organic matter in the water to be treated into easily-degradable organic matter, and it can be used for deodorization, decolorization, disinfection, oxidation of iron and manganese ions, decomposition of organic matter, and trihalomethane formation ability. It is effective for reduction and is one of the typical treatment methods for advanced water treatment. Further, as described above, by providing a biological activated carbon treatment system in the subsequent stage, it is possible to microbially decompose easily decomposable organic substances and to adsorb and remove trace chemical substances.

For example, a lot of humic substances, which are decomposition products of animal and plant bodies, are dissolved in surface water which is treated water for water purification treatment.
This humic substance is a residue obtained by decomposing animal and plant bodies by microorganisms, and is classified as the above-mentioned hardly decomposable organic substance, and is colored, and the unsaturated bond that causes this coloring is contained in the molecule. Has a lot.

  Examples of such humic substances include the aforementioned fulvic acid-like organic substances. This fulvic acid-like organic substance is a main component of a precursor of an organic halogen compound such as trihalomethane having carcinogenicity in chlorination of tap water.

  The humic substance in the water to be treated is highly reactive to ozone gas, and the ozone reaction with the ozone gas oxidizes the unsaturated bond in the humic substance, resulting in an easily degradable organic substance that can be easily eaten by microorganisms of biological activated carbon.

On the other hand, the water to be treated sent from the coagulation sedimentation pond contains other dissolved organic matter such as harmful residual agricultural chemicals and odorous substances. The reactivity of these reactants with ozone is slower than that of humic substances.
Thus, in the water to be treated, there are a mixture of a reactive substance having a fast decomposition reaction with respect to the injected ozone gas and a reactive substance having a slow decomposition reaction.

  For this reason, the ozone reaction can be considered in two stages: an ozone reaction having a high decomposition reactivity mainly decomposing and decolorizing fulvic acid-like organic substances, and an ozone reaction having a low decomposition reactivity.

  On the other hand, if the dissolved ozone concentration in the ozone-treated water is too high, there arises a problem that carcinogenic bromate ions are generated as a by-product due to the ozone reaction.

  Considering the above situation, in the ozone gas injection control system according to the present invention, the ozone contact tanks 3a, 3b, 3c, and 3d in the ozone reaction tank 3 are divided into two groups G1 and G2. In this case, the 1st group G1 consists of ozone contact tank 3a, and the 2nd group G2 consists of ozone contact tanks 3b, 3c, and 3d.

  Here, in the first group G1, in the ozone contact tank 3a, the ozone reaction with respect to the reactant having the property that the decomposition reaction with respect to the ozone gas is fast is performed, and the more ozone gas is injected, the more ozone reaction progresses and the injection is performed. Absorbs gas-phase ozone regardless of ozone concentration.

  As shown in FIG. 3A, this ozone reaction occurs at the bubble interface and the boundary film, and the reaction efficiency is almost 100%. That is, the diffusion of the ozone gas itself when the ozone gas moves from the gas phase, which is a small bubble, to the liquid phase is a so-called diffusion-controlled rate limiting reaction.

  In the ozone contact tank 3a of the first group G1, since the injected ozone gas immediately reacts with the water to be treated, the dissolved ozone concentration becomes very small, and the ozone injection rate is controlled by detecting this dissolved ozone concentration. It is difficult to do.

On the other hand, in the ozone contact tanks 3b, 3c, and 3d of the second group G2, as shown in FIG. 3 (b), the ozone reaction exclusively with the reactant having the property of slow decomposition reaction with the ozone gas is performed. This ozone reaction is so-called reaction rate limiting, in which the ozone reaction does not proceed unless time elapses. That is, no matter how much ozone gas is injected, the ozone gas is not immediately used for the ozone reaction.
Moreover, bromate ion which is a harmful substance is produced | generated by the ozone reaction shown in FIG.3 (b).

  The ozone treatment in the present embodiment will be described in more detail using the fluorescence intensity measured by the fluorescence intensity analyzers 6a, 6b, and 6c with reference to FIG.

FIG. 4 is a graph showing the correlation between the ozone injection rate when the ozone gas is injected into the water to be treated, the relative fluorescence intensity of the ozone treated water, the bromate ion, and the dissolved ozone concentration as described above.
In FIG. 4, the horizontal axis of the graph is the ozone injection rate (mg / L), the two-dot chain line portion in the graph is the relative fluorescence intensity of the ozone treated water, and the value is displayed on the vertical axis on the left side of the graph. The solid line part in the graph is the bromate ion concentration (μg / L) and its value is displayed on the left vertical axis of the graph, and the dotted line part in the graph is the dissolved ozone concentration (mg / L) The value is displayed on the right vertical axis of the graph.

  As shown in FIG. 4, it can be seen that the relative fluorescence intensity of the ozone-treated water decreases as the ozone injection rate increases, and the fulvic acid-like organic matter is rapidly decomposed by the ozone gas as described above. That is, the ozone reaction process can be grasped by measuring the relative fluorescence intensity of the ozone-treated water.

  As shown in FIG. 4, when the ozone injection rate is low, for example, 0.8 mg / L or less, the relative fluorescence intensity of the ozone-treated water is significantly reduced as the ozone injection rate is increased. It can be seen that ozone is effectively used for the reaction.

On the other hand, when the ozone injection rate is high, for example, exceeding 1 mg / L, the relative fluorescence intensity of the ozone-treated water hardly decreases even if the ozone injection rate increases.
From this, in the injection of ozone gas into the water to be treated, the ozone injection rate before reaching the point where the change in the relative fluorescence intensity of the ozone treated water becomes small is the optimum value.

  The dissolved ozone concentration when the ozone injection rate is as low as 0.8 mg / L or less, for example, is 0 to 0.02 mg / L from FIG. 4, and it is difficult to measure with the dissolved ozone concentration meter 12. It has become. On the other hand, when the ozone injection rate is so high as to exceed 1 mg / L, the dissolved ozone concentration greatly increases with the increase of the ozone injection rate, causing a problem that bromic acid is generated.

The amount of bromate ions generated is shown as a dotted line in FIG. Bromate ion has carcinogenicity, and the upper limit of the water quality standard is 10 μg / L. For this reason, it is necessary for the ozone gas injection control device 10 to control the bromate ion to be 10 μg / L or less in the ozone treatment.
Here, when only the dissolved ozone concentration is used as the water quality index, as described above, the dissolved ozone concentration cannot be detected unless the ozone injection rate exceeds 1 mg / L. Therefore, the bromate ion concentration is set to 10 μg. It becomes difficult to control to / L or less.
On the other hand, when the relative fluorescence intensity of the ozone-treated water is used as an index, control in a low ozone injection rate region where the ozone injection rate is, for example, 0.8 mg / L or less is possible. Can be controlled to 10 μg / L or less.

  Next, the relationship between the ozone gas injection rate and the trihalomethane production state of ozone-treated water will be described.

FIG. 5 is a graph showing the correlation between the ozone injection rate, the relative fluorescence intensity of ozone-treated water, and the concentration of trihalomethane formation ability.
In the graph of FIG. 5, the horizontal axis is the ozone injection rate (mg / L), the solid line portion in the graph is the relative fluorescence intensity of the ozone-treated water, and the value is displayed on the vertical axis on the left side of the graph. The dotted line in the figure is the concentration (mg / L) of trihalomethane generating ability in the ozone-treated water, and the value is displayed on the vertical axis on the right side of the graph.

As shown in FIG. 5, the concentration of trihalomethane generating ability decreases greatly at the beginning of ozone gas injection, and after that, even if the ozone injection rate is increased, it hardly changes or slightly increases.
As described above, when the amount of decrease in relative fluorescence intensity with respect to the ozone injection rate is small, that is, when the ozone injection rate exceeds 1 mg / L, the concentration of trihalomethane generating ability decreases even if the ozone injection rate is increased. It can be seen that ozone gas is not used effectively.

Next, the relationship between the ozone gas contact time, the relative fluorescence intensity of the ozone-treated water, and the dissolved ozone concentration will be described.
FIG. 6 shows the relationship between the time elapsed since the ozone gas was injected into and contacted with the water to be treated, the relative fluorescence intensity of the water to be treated, and the dissolved ozone concentration.
In FIG. 6, the horizontal axis of the graph indicates the time (minutes) that has elapsed since the ozone gas was injected into the water to be treated, the solid line portion of the graph indicates the relative fluorescence intensity of the ozone treated water, and the value is The vertical axis on the left side of the graph indicates the dissolved ozone concentration (mg / L), and the value is displayed on the vertical axis on the right side of the graph.

  In the graph shown in FIG. 6, the region up to 5 minutes after the ozone gas is injected into the water to be treated shows a state in the ozone contact tank 3a, and this time is 5 minutes to 10 minutes. The region indicates the state in the ozone contact tank 3b, the region in which this time is 10 minutes to 15 minutes indicates the state in the ozone contact tank 3c, and the region in which this time is 15 minutes to 20 minutes is the ozone contact tank 3d. The state inside is shown.

  As shown in FIG. 6, the ozone treatment water in the ozone contact tank 3a of the first group G1 located upstream of the ozone reaction tank 3 has a large change in relative fluorescence intensity due to the injection of ozone gas, and also has a control response. Since the speed is increased, the controllability by the fluorescence intensity analyzer 6b is improved. On the other hand, the ozone-treated water in the ozone contact tanks 3b, 3c and 3d of the second group G2 located downstream of the ozone reaction tank 3 has a large change in dissolved ozone concentration due to the injection of ozone gas. Controllability by the total 12 is improved.

  Here, the case where the ozone gas injection control device 10 performs control combining the above-described FF control and FB control will be described in detail.

  When performing control that combines FF control and FB control, the ozone gas injection control device 10 detects the fluorescence intensity of the water to be treated in the introduction line 1a and the ozone contact tanks 3a, 3b, 3c, and 3d after ozone contact. It is preferable to adjust the ozone injection rate based on the fluorescence intensity change rate obtained from the fluorescence intensity of ozone reaction water.

FIG. 7 is a graph showing the correlation between the ozone injection rate and the relative fluorescence intensity of ozone treated water when the quality of the treated water (relative fluorescence intensity) changes. In FIG. 7, the horizontal axis of the graph represents the ozone injection rate (mg / L), the vertical axis of the graph represents the relative fluorescence intensity of the ozone treated water, and the solid line portion in the graph represents the relative fluorescence intensity of the water to be treated. The correlation between the ozone injection rate and the relative fluorescence intensity for 50, 30, and 20 is shown.
In the present embodiment, for example, as shown in FIG. 7, the ozone gas injection control device 10 sets the ozone injection rate such that the decrease rate of the relative fluorescence intensity of the ozone treated water relative to the relative fluorescence intensity of the water to be treated is 65%, for example. Optimal injection control of ozone gas can be performed by setting and controlling.

  As described above, the plurality of ozone contact tanks 3a, 3b, 3c, and 3d in the ozone reaction tank 3 are classified into at least two groups G1 (ozone contact tank 3a) and G2 (ozone contact tanks 3b, 3c, and 3d). The ozone gas injection control device 10 is injected into the water to be treated by controlling the injection rate of ozone gas injected into each ozone contact tank 3a, 3b, 3c for each group G1, G2. The ozone treatment corresponding to the reactive substance having a quick reaction to the ozone gas and the reactive substance having a slow reaction is performed in each of the groups G1 and G2. As a result, the minimum necessary ozone injection according to these reactants is performed, and therefore generation of useless energy for generating ozone gas can be suppressed. And since it can suppress that dissolved ozone concentration becomes excess, the production | generation of bromate ion can be suppressed and the quality of ozone treated water can be kept appropriate.

Second Embodiment Next, a second embodiment of the present invention will be described. 8 and 9 are diagrams showing a second embodiment of the present invention.
In the ozone injection system according to the second embodiment, a plurality of ozone gas injection devices are provided, and only the ozone gas piping system connected from each ozone gas injection device to each ozone contact tank is different. This is substantially the same as the first embodiment shown in FIG.
Further, in the second embodiment shown in FIGS. 8 and 9, the same parts as those in the first embodiment shown in FIG.

  8 is an explanatory view showing an ozone gas injection control system according to the second embodiment of the present invention, and FIG. 9 is an explanatory view showing an ozone gas piping system used in the ozone gas injection control system of FIG. .

  As shown in FIG. 8, in the ozone gas injection control system, the water to be treated introduced through the introduction line 1a sequentially flows, and a plurality of ozone contact tanks 3a, 3b each having ozone injection ports 9a, 9b, 9c. 3c and 3d, and two ozone gas injection devices 7a and 7b. Among these, the ozone gas injection devices 7a and 7b are installed corresponding to the two groups G1 and G2 that divide the plurality of ozone contact tanks 3a, 3b, 3c, and 3d, respectively.

  Specifically, the ozone gas injection device 7a is for injecting ozone gas into the ozone contact tank 3a related to the first group G1, while the ozone gas injection device 7b is used for the ozone contact tank 3b related to the second group G2. 3c is injected with ozone gas.

  Further, as shown in FIG. 9, a first pipe having an air / ozone header 16d between one ozone gas injection device 7a and the ozone contact tank 3a of the first group G1 corresponding to the ozone gas injection device 7a. A second ozone gas injection device 7b having an air / ozone header 16e between the other ozone gas injection device 7b and the ozone contact tanks 3b, 3c, 3d of the second group G2 corresponding to the other ozone gas injection device 7b; The piping 16b is installed. An ozone gas piping system is configured by the first piping 16a having the air / ozone header 16d and the second piping 16b having the air / ozone header 16e.

  In this ozone gas piping system, as shown in FIG. 9, the first piping 16a and the second piping 16b are connected to each other via an on-off valve 16c.

The first pipe 16a and the second pipe 16b are connected to an air supply device (not shown) for supplying air into the pipes 16a and 16b via the air / ozone headers 16d and 16e, respectively. Yes.
It is preferable that the air supply device can adjust the discharge air volume to 67% to 133% of the rated air volume.
In the ozone gas piping system according to the second embodiment, the first piping 16a and the second piping 16b have air / ozone headers 16d and 16e capable of switching between air and ozone, and the first piping 16a and the second piping 16b. The first pipe 16a and the second pipe 16b are connected via an on-off valve 16c. The first pipe 16a and the second pipe 16b are connected to an air supply device via air / ozone headers 16d and 16e, respectively. For this reason, air and ozone can be supplied to the ozone contact tanks 3a, 3b, and 3c in parallel using two paths, that is, the first pipe 16a and the second pipe 16b, respectively.

Next, the operation of the present embodiment having such a configuration will be described.
In the operation of the second embodiment, the same operation as that of the above-described first embodiment is performed except that the following points are different.

In the first group G1, ozone treatment with a quick decomposition reaction mainly including decomposition and decolorization of a fulvic acid-like organic substance is mainly performed. That is, the ozone gas injection control device 10 performs concentration change control so that the amount of gas containing ozone gas is constant and the ozone gas concentration in the gas becomes high.
Thus, by making the amount of gas constant, the diameter and number of bubbles of this gas are made constant. The ozone gas injection rate changes as the ozone gas concentration in the gas changes. In the first group G1, the concentration of the reactants is high. Therefore, even when the ozone gas concentration is set high, the ozone reaction is completed to the extent that dissolved ozone is not generated by the fast ozone reaction.

  Specifically, the ozone gas injection control device 10 controls one ozone gas injection device 7a to adjust the ozone injection rate so that the maximum value becomes 0.5 mg / L. In the control of one ozone gas injection device 7a by the ozone gas injection control device 10, FF control is performed based on the relative fluorescence intensity of the water to be treated measured by the fluorescence intensity analyzer 6a.

  On the other hand, in the second group G2, in order to finish the ozone reaction and reduce by-products such as bromate ions and organic peroxides due to excessive injection, the amount of gas containing ozone gas is kept constant. Ozone gas is injected so that the ozone gas concentration becomes low.

  Specifically, by performing FB control by the ozone gas injection control device 10 so that the relative fluorescence intensity of the ozone treated water in the ozone contact tank 3d measured by the fluorescence intensity analyzer 6c is in the range of 5-10. The other ozone gas injection device 7b is controlled.

  In addition, an air supply device is connected to the first pipe 16a and the second pipe 16b via air / ozone headers 16d and 16e, and the first pipe 16a and the second pipe 16b are connected to each other. Since the opening / closing valve 16c is provided, the opening / closing valve 16c can be opened to send cleaning air from the air supply device to the ozone contact tanks 3a, 3b, 3c, 3d in a lump. 3b, 3c, 3d can be efficiently cleaned with air.

In addition, the ozone injection control system of this invention is not limited to said aspect, A various change can be added.
Next, an ozone injection control system according to a modification of the present invention will be described. 10 to 12 are diagrams for explaining an ozone injection control system in a modification of the present invention.
Among these, FIG. 10 is a graph showing the correlation between the ozone injection rate (mg / L) and the relative fluorescence intensity when the water temperature of the water to be treated is 20 degrees or 30 degrees, and FIG. FIG. 12 is a graph showing the correlation between the ozone injection rate (mg / L) and the relative fluorescence intensity when the pH value of the treated water is 7 or 8, and FIG. It is a graph which shows the correlation with the ozone injection rate (mg / L) in the case of being 30 and 40, and relative fluorescence intensity, respectively.

In the ozone injection control system of this modification, as shown in FIG. 1, water quality measuring devices 20 are provided in the introduction line 1a and the ozone contact tanks 3a, 3b, 3c, and 3d, and the ozone gas injection control device 10 is The following control is performed. Other configurations are substantially the same as those in the first or second embodiment.
The water quality measuring device 20 measures the pH of the water to be treated in the introduction line 1a and the temperature of the ozone-treated water in each of the ozone contact tanks 3a, 3b, 3c, and 3d, and the pH of the ozone-treated water. pH meter 20b.
The water quality measuring device 20 is connected to the ozone gas injection control device 10.

The operation of such an ozone injection control system will be described.
1 and 8, the water temperature meter 20a of the water quality measuring device 20 measures the temperature of the water to be treated in the introduction line 1a, and this water quality information is sent to the ozone gas injection control device 10.
The ozone gas injection control device 10 sets a target value (FL _SV ) of relative fluorescence intensity by the following formula (1) based on the water temperature (t) of the water to be treated measured by the water temperature gauge 20a.
FL _SV = (1 + 0.02 × (t−20)) × 10 Expression (1)

According to Formula (1), for example, when the water temperature of the water to be treated is 20 degrees and 30 degrees, the target values (FL _SV ) of the relative fluorescence intensity are 10 and 12, respectively.

Next, based on the graph showing the correlation between the ozone injection rate (mg / L) at each water temperature and the relative fluorescence intensity as shown in FIG. 10, the ozone gas injection rate in the control of the ozone gas injection control device 10 is The relative fluorescence intensity corresponding to this injection rate is corrected so as to be the target value (FL _SV ) calculated by the equation (1).
According to FIG. 10, for example, when the water temperature of the treated water measured by the water temperature gauge 20a is 20 degrees, the ozone gas injection rate is corrected to 0.9 mg / L, and the water temperature is 30 degrees. The ozone gas injection rate is corrected to 1.1 mg / L.

  The timing for correcting the injection rate of the ozone gas is determined based on the change in the water temperature of the water to be treated measured by the water temperature gauge 20a.

  The correction of the ozone gas injection rate is not limited to the one corresponding to the water temperature of the water to be treated in the introduction line 1a. For example, the ozone treatment water in each ozone contact tank 3a, 3b, 3c, 3d is adjusted to the water temperature. It may be a corresponding one.

Further, the ozone gas injection control device 10 can perform the following control. That is, the pH value of the water to be treated in the introduction line 1 a is measured by the pH meter 20 b of the water quality measuring device 20, and this water quality information is sent to the ozone gas injection control device 10.
The ozone gas injection control device 10 sets a target value (FL _SV ) of relative fluorescence intensity by the following equation (2) based on the pH value (pH) of the water to be treated measured by the pH meter 20b.
FL _SV = (1 + 0.01 × (pH−7)) × 10 Formula (2)

According to Expression (2), for example, when the pH value of the water to be treated is 7 or 8, the target value (FL _SV ) of the relative fluorescence intensity is 10 and 10.1, respectively.

Next, based on the graph showing the correlation between the ozone injection rate (mg / L) at each pH value and the relative fluorescence intensity as shown in FIG. 11, the ozone gas injection rate in the control of the ozone gas injection control device 10 is The relative fluorescence intensity corresponding to the injection rate is corrected to be the target value (FL _SV ) calculated by the equation (2).
According to FIG. 11, for example, when the pH value of the water to be treated measured by the pH meter 20b is 7, the ozone gas injection rate is corrected to 0.9 mg / L, and this pH value is 8. The ozone gas injection rate is corrected to 1.0 mg / L.

  The timing for correcting the injection rate of the ozone gas is determined based on the change in the pH value of the water to be treated measured by the pH meter 20b.

  The correction of the ozone gas injection rate is not limited to that corresponding to the pH value of the water to be treated in the introduction line 1a. For example, the pH of the ozone treated water in each of the ozone contact tanks 3a, 3b, 3c, and 3d. It may correspond to a value.

Further, the ozone gas injection control device 10 can perform the following control. That is, the relative fluorescence intensity of the water to be treated in the introduction line 1a is measured by the fluorescence intensity analyzer 6a, and this water quality information is sent to the ozone gas injection control device 10.
The ozone gas injection control device 10 sets the target value (FL _SV ) of the relative fluorescence intensity by the following formula (3) based on the relative fluorescence intensity (FL ₀ ) of the water to be treated measured by the fluorescence intensity analyzer 6a. To do.
FL _SV = FL ₀ − (0.5 × FL ₀ × (1 + 0.005 × (FL ₀ −30)) + 4.5) Equation (3)

According to Equation (3), for example, when the relative fluorescence intensity of the water to be treated is 20, 30, and 40, the target values (FL _SV ) of the relative fluorescence intensity are 6, 10.5, and 14.5, respectively. .

Next, in the control of the ozone gas injection control device 10 based on the graph showing the correlation between the ozone injection rate (mg / L) and the relative fluorescence intensity at each relative fluorescence intensity of the water to be treated as shown in FIG. The ozone gas injection rate is corrected so that the relative fluorescence intensity corresponding to this injection rate becomes the target value (FL _SV ) calculated by the equation (3).
According to FIG. 11, for example, when the relative fluorescence intensity of the water to be treated measured by the fluorescence intensity analyzer 6a is 20, the ozone gas injection rate is corrected to be 0.7 mg / L. Is corrected so that the ozone gas injection rate is 0.8 mg / L, and when the relative fluorescence intensity is 40, the ozone gas injection rate is corrected to be 0.9 mg / L. .

  The timing for correcting the injection rate of the ozone gas is determined based on the change in the relative fluorescence intensity of the water to be treated measured by the fluorescence intensity analyzer 6a.

  As described above, the ozone gas injection control device 10 uses the temperature of the water to be treated or ozone treated water measured by the water temperature gauge 20a, the pH value of the water to be treated or ozone treated water measured by the pH meter 20b, or the fluorescence intensity. The correction of the ozone gas injection rate based on any one of the relative fluorescence intensities of the water to be treated measured by the analyzer 6a has been described. The correction of the ozone gas injection rate is based on the above water temperature and pH value. Also, control by relative fluorescence intensity may be performed in combination.

  Next, the following control by the ozone gas injection control device 10 may be performed. That is, FIG. 13 is a graph showing the relationship between the ozone injection rate (mg / L) and the relative fluorescence intensity when ozone gas is injected into the water to be treated.

  The ozone injection control system in this modification has the same configuration as that of the first or second embodiment except that the ozone gas injection control device 10 performs the following control.

  In the control by the ozone gas injection control device 10, the ozone gas injection rate for each group is calculated based on the fluorescence intensity measured in advance by all the fluorescence intensity analyzers 6b and 6c.

A specific operation of such an ozone injection control system will be described.
For example, the ozone gas is periodically injected into the ozone treatment contact tanks 3a, 3b, and 3c so that the ozone gas injection rates in the groups G1 and G2 are the same at 8 am.
Then, after the ozone reaction is stabilized, for example, at 9 am, the relative fluorescence intensity of the water to be treated in the introduction line 1a measured by the fluorescence intensity analyzer 6a and the injection rate of the ozone gas, and the fluorescence intensity analysis that is collected by the sampling port 4a. Relative fluorescence intensity and ozone gas injection rate of ozone treated water in the ozone contact tank 3a measured by the meter 6b, ozone treated water in the ozone contact tank 3b sampled by the water sampling port 4b and measured by the fluorescence intensity analyzer 6b The relative fluorescence intensity and the ozone gas injection rate are respectively stored in the ozone gas injection control device 10.
Next, the changeover valve is switched so as to measure the relative fluorescence intensity of the ozone-treated water sampled from the sampling port 4c, and after the measured value by the fluorescence intensity analyzer 6c is stabilized, for example, 15 minutes later, sampling is performed by the sampling port 4c. The ozone gas injection control device 10 stores the relative fluorescence intensity of ozone-treated water in the ozone contact tank 3c measured by the fluorescence intensity analyzer 6c and the injection rate of ozone gas.

The relative fluorescence intensity and the ozone gas injection rate stored in the ozone gas injection controller 10 are plotted on a graph as shown in FIG. And in the graph of FIG. 13, the plot points with which the magnitude | size of an ozone injection rate adjoins are connected with a straight line.
Next, a straight line having an inclination of −23 (1 / (mg / L)) is drawn from the plot point of the relative fluorescence intensity of the water to be treated (graph point A), and a straight line connecting the plot points described above Find the intersection of The relative fluorescence intensity at this intersection is taken as the control target value.

  Here, the automatic change of the control target value of the relative fluorescence intensity is periodically performed at 8:00 am, but the timing of this automatic change is determined by the relative fluorescence intensity, water temperature, and pH value of the water to be treated. Thus, the control target value corresponding to the change in water quality can be automatically changed. For example, when the relative fluorescence intensity of the water to be treated has changed by 10 from the average value of 2 hours to 1 hour before, the operation for obtaining the control target value of the relative fluorescence intensity is automatically started.

  As a result, when the control target value of the relative fluorescence intensity is automatically changed, the control target value of the relative fluorescence intensity can be automatically calculated from each relative fluorescence intensity value, and the temporary water quality component changes. In this case, it is possible to cope with a change in water quality over time, and the ozone gas injection rate can be calculated along the control target value of the relative fluorescence intensity.

The block diagram which shows the structure of the ozone gas injection | pouring control system by the 1st Embodiment of this invention. Graph showing the correlation between fulvic acid concentration in water and relative fluorescence intensity Explanatory drawing showing the state of ozone reaction for reactants with fast decomposition reaction and ozone reaction for reactants with slow decomposition reaction A graph showing the correlation between the ozone injection rate when ozone gas is injected into the water to be treated, the relative fluorescence intensity of ozone-treated water, and the dissolved ozone concentration Graph showing the correlation between the ozone injection rate when ozone gas is injected into the water to be treated, the relative fluorescence intensity of ozone-treated water, and the ability to produce trihalomethanes The graph which shows the relationship between the time which passed since ozone gas was inject | poured into the to-be-processed water, and the relative fluorescence intensity of the to-be-processed water, and dissolved ozone concentration Graph showing the correlation between the ozone injection rate and the relative fluorescence intensity of ozone-treated water when the relative fluorescence intensity of the treated water changes The block diagram which shows the structure of the ozone gas injection | pouring control system by the 2nd Embodiment of this invention. Explanatory drawing which shows the ozone gas piping system used for the ozone gas injection | pouring control system of FIG. Graph showing the correlation between the ozone injection rate and the relative fluorescence intensity when the water temperature of the water to be treated is 20 degrees or 30 degrees The graph which shows the correlation with an ozone injection rate in case pH value of to-be-processed water is 7 or 8, and relative fluorescence intensity, respectively Graph showing the correlation between the ozone injection rate and the relative fluorescence intensity when the relative fluorescence intensity of the water to be treated is 20, 30, and 40, respectively. Graph showing the relationship between ozone injection rate and relative fluorescence intensity when ozone gas is injected into the water to be treated Configuration diagram showing the configuration of a conventional ozone gas injection control system

Explanation of symbols

1a introduction line 1b outflow line 3 ozone reaction tanks 3a, 3b, 3c, 3d ozone contact tanks 4a, 4b, 4c, 4d sampling ports 5a, 5b, 5c, 5d switching valves 6a, 6b, 6c fluorescence intensity analyzers 7, 7a 7b Ozone gas injection devices 9a, 9b, 9c Ozone injection port 10 Ozone gas injection control device 12 Dissolved ozone concentration meter 15b, 15c Analysis introduction line 16a First piping 16b Second piping 16c On-off valve 16d, 16e Air / ozone header 20 Water quality measuring device 20a Water temperature meter 20b pH meter G1 First group G2 Second group

Claims (11)

The water to be treated introduced through the introduction line sequentially flows, an ozone reaction tank composed of a plurality of ozone contact tanks each having an ozone inlet, and
An ozone gas injection device for injecting ozone gas from each ozone contact port into each ozone contact tank and reacting the water to be treated with ozone gas to obtain ozone treated water;
A fluorescence intensity analyzer that is provided in the introduction line and / or any one of the ozone contact tanks, and measures the fluorescence intensity of at least one of the water to be treated in the introduction line and each ozone treated water in each ozone contact tank; ,
An ozone gas injection control device that controls the ozone gas injection device based on the fluorescence intensity measured by the fluorescence intensity analyzer and adjusts the injection rate of ozone gas injected into each ozone contact tank;
The plurality of ozone contact tanks are divided into at least two groups,
The ozone gas injection control device controls the ozone gas injection device based on the fluorescence intensity measured by the fluorescence intensity analyzer, and adjusts the injection rate of ozone gas injected into each ozone contact tank for each group. An ozone gas injection control system characterized by that. The water to be treated introduced through the introduction line sequentially flows, an ozone reaction tank composed of a plurality of ozone contact tanks each having an ozone inlet, and
At least two ozone gas injection devices for injecting ozone gas into each ozone contact tank from the ozone injection port to react the treated water and ozone gas to obtain ozone treated water;
A fluorescence intensity analyzer that is provided in the introduction line and / or any one of the ozone contact tanks, and measures the fluorescence intensity of at least one of the water to be treated in the introduction line and each ozone treated water in each ozone contact tank; ,
Based on the fluorescence intensity measured by the fluorescence intensity analyzer, each ozone gas injection device is controlled and an ozone gas injection control device that adjusts the injection rate of ozone gas injected into each ozone contact tank, and
A plurality of ozone contact tanks are divided into at least two groups, and each ozone gas injection device is installed to correspond to a group of ozone contact tanks,
The ozone gas injection control device controls the ozone gas injection device corresponding to each group based on the fluorescence intensity measured by the fluorescence intensity analyzer, and determines the injection rate of ozone gas injected into each ozone contact tank. An ozone gas injection control system that adjusts for each group.   One ozone gas injection device and a group of ozone contact tanks corresponding to this ozone gas injection device are connected by a single pipe, the other ozone gas injection device and a group of ozone contact tanks corresponding to this ozone gas injection device The ozone gas injection control system according to claim 2, wherein the pipe is connected by another pipe, and the one pipe and the other pipe are connected to each other via an on-off valve.   The ozone gas injection according to any one of claims 1 to 3, wherein an additional fluorescence intensity analyzer for measuring the fluorescence intensity of the ozone treated water flowing out of the ozone reaction tank is provided downstream of the ozone reaction tank. Control system.   The analysis introduction line for guiding the ozone treated water in the plurality of ozone contact tanks to the fluorescence intensity analyzer is set between the ozone contact tank and the fluorescence intensity analyzer. The ozone gas injection control system according to any one of the above.   6. The dissolved ozone concentration meter for measuring the dissolved ozone concentration of the ozone-treated water in the ozone contact tank is provided in the ozone contact tank of the downstream group. Ozone gas injection control system. Water quality measurement that is provided in the introduction line and / or any ozone contact tank and measures the water temperature and / or pH of at least one of the water to be treated in the introduction line and each ozone treated water in each ozone contact tank. Further equipped with a vessel,
The ozone gas injection control device corrects the ozone gas injection control for each group based on at least one of the fluorescence intensity measured by the fluorescence intensity analyzer, the water temperature measured by the water quality measuring instrument, and the pH. The ozone gas injection control system according to any one of claims 1 to 6.   The ozone gas injection control device corrects the ozone gas injection control for each group based on at least one of the fluorescence intensity measured by the fluorescence intensity analyzer, the water temperature measured by the water quality meter, and the pH. 8. The ozone gas injection control system according to claim 7, wherein the time is determined. A fluorescence intensity analyzer is provided in each ozone contact tank,
9. The control by the ozone gas injection control device, wherein the ozone gas injection control for each group is corrected in advance based on fluorescence intensity measured by a plurality of fluorescence intensity analyzers. The ozone gas injection control system according to any one of the above.   The fluorescence intensity analyzer irradiates the water to be inspected with light having an excitation wavelength of 320 to 370 nm, and measures the fluorescence wavelength of 400 to 450 nm in the fluorescence spectrum to measure the fluorescence of water to be inspected. The ozone gas injection control system according to any one of claims 1 to 9, wherein the system measures intensity. The fluorescence intensity analyzer is provided in each of the introduction line and at least one ozone contact tank,
The ozone gas injection control device controls the ozone gas injection device based on the fluorescence intensity change rate obtained from the fluorescence intensity from the fluorescence intensity analyzer of the introduction line and the fluorescence intensity from the fluorescence intensity analyzer of the ozone contact tank. The ozone gas injection control system according to any one of claims 1 to 10.

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