JP3944268B2 - Pressurized downward injection type multi-stage ozone contact tank and its control method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pressurized down-injection type multi-stage ozone contact tank that is useful when applied to an ozone treatment apparatus as a water and sewage treatment method, and a control method therefor.
[0002]
[Prior art]
In recent years, water pollution in rivers and lakes has progressed along with the deterioration of the water environment in urban areas. The combination of conventional coagulation sedimentation, sand filtration, and chlorination alone has the chromaticity and odor of raw water for water supply. There is a limit point in the removal effect. In particular, about 70% of the water source used as tap water in Japan depends on lake water, dam water, and river water called surface water, and biological activities associated with eutrophication are active in these lake water and dams. The generation of mold odors and algae odors due to the conversion to the river, and the other river water is filled with organic matter and ammonia nitrogen contained in various wastewater, and these inflows are completely purified by the natural purification of the river. You can't expect to do it.
[0003]
In order to cope with the deterioration of water quality due to such high economic growth, prechlorination is generally adopted, but trihalomethane (THM), an organochlorine compound generated in the water purification process using prechlorination, is adopted. Is known to have carcinogenic properties. Advanced water purification system that introduces ozone treatment or combined treatment of ozone treatment and activated carbon treatment during the water purification operation process has been studied as a countermeasure against carcinogenic substances such as trihalomethane and elimination of mold odor and algae odor from water sources. ing.
[0004]
Ozone gas has the action of oxidizing and removing dissolved harmful substances dissolved in water with its own strong oxidizing power, and recently it has been adopted not only for drinking water but also for treating sewage. However, the cost of ozone treatment is about twice as high as that of chlorination, so it is required to further improve the treatment effect of ozone gas. Therefore, by creating countless fine bubbles of ozone gas, Increasing contact efficiency and efficiently dissolving and absorbing ozone gas in water is an essential requirement.
[0005]
Conventionally, as means for increasing the contact efficiency and absorption efficiency of ozone gas, an air diffuser type ozone contact tank or a downward injection type ozone contact tank (U tube type ozone contact tank) is known. As an example of the above-described diffuser tube type ozone contact tank, for example, “Ozone-utilized water treatment technology” (Isao Somiya, Pollution Control Technology Club, May 1989) includes an up-and-down counterflow type ozone as shown in FIG. An example of a contact tank is disclosed.
[0006]
That is, in this example, the partition walls 2 and 2 rising from the bottom surface and the partition walls 3 and 3 suspended from the top surface are disposed inside the ozone contact tank 1, and the gas phase portion is separated by the partition walls 2 and 3. In addition, a plurality of overflow type reaction chambers in which the liquid phase portions communicate with each other are configured. Further, a diffuser tube 4.4 made of ceramic or the like having a fine hole of several tens of μm is disposed in the vicinity of the inner bottom surface of each chamber, and ozone gas obtained from an ozone generator not shown is sent into the diffuser tube 4.4. Then, the water to be treated and ozone gas flowing in from the inflow port 5 come into contact with each other as a counter flow as indicated by arrows A and A, whereby the contact efficiency of the ozone gas is increased and the ozone treated water 10 flows out.
[0007]
The other downward injection type ozone reaction tank (U-tube type ozone reaction tank) is also called an injector type ozone contact tank, and an inner tube 6 is disposed inside the vertically long ozone contact tank 1 as shown in FIG. The ozone gas obtained by the ozone generator 7 is sent from the upper part of the inner pipe 6 through the gas discharge pipe 8. And the to-be-processed water and ozone gas which flow in from the inlet 5 of the ozone gas contact tank 1 are contacted continuously as a downward flow in the inner pipe 6 to perform desired ozone treatment. It rises along the wall surface and flows out as ozone treated water 10 from the upper part of the ozone contact tank 1. Unreacted ozone gas is sent to the exhaust ozone treatment device 9 and cleaned.
[0008]
The length of the ozone contact tank 1 in the vertical direction is as high as 20 to 30 meters, so that the water pressure in the inner tube 6 is 2.0 to 2.5 (kgf / cm). ² ) Level.
[0009]
In this U-tube type ozone contact tank, the gas-liquid contact effect between the ozone gas and the water to be treated is enhanced by the turbulent flow generated in the inner pipe 6, and the ozone gas is increased by the water pressure that increases as the ozone gas flows down in the inner pipe 6. Since dissolution in water is promoted, the ozone dissolution efficiency is improved by 5-10% compared to the diffuser system, and the contact time between the ozone gas and the water to be treated can be about 5 times or more and the reaction tank It has a feature that the residence time can be shortened to 1/5 or less. In addition, since the ozone contact tank is vertically long, it has the advantage that the installation space of the ozone treatment facility can be reduced to 1/5 that of the air diffuser.
[0010]
By using such an ozone reaction tank, it is possible to remove unpleasant odors and chromaticity of water to be treated and oxidative removal of harmful substances by ozone gas having a stronger oxidizing power than chlorine (for the above U tube type ozone treatment apparatus). , Pages 76-77 of the 2nd Annual Meeting of the Japan Ozone Society, see Toriyama et al., “Organic substance removal characteristics of U-tube type ozone contact tank”).
[0011]
[Problems to be solved by the invention]
However, the ozone contact tank employed in the above-described advanced water purification system or the like has not established a control method for increasing the absorption efficiency of ozone gas to the water to be treated. In addition, there is a problem that it is necessary to lengthen the residence time of the ozone contact tank, resulting in an increase in cost due to an increase in the size of the apparatus.
[0012]
For example, in the diffuser tube type ozone contact tank shown in FIG. 9, the iron or manganese oxidized by the ozone gas adheres to the surface of the diffuser tube 4 as the process proceeds, and the time-dependent ozone caused by the clogging of the diffuser tube 4 There is a possibility of causing a phenomenon of a decrease in absorption efficiency, and there is a problem that the diffuser itself needs to be replaced in response to this phenomenon. Furthermore, in order to take sufficient reaction time with ozone gas, the contact tank has to be enlarged, leading to an increase in the cost required for equipment costs and the like, and a large site area for installing the device will be required. It is difficult to adopt in areas where it is difficult to secure land, such as water purification plants in urban areas.
[0013]
The other U tube type ozone contact tank shown in FIG. 10 is improved by about 5 to 10% in ozone dissolution efficiency compared with the diffuser tube type ozone contact tank, and the contact time between the ozone gas and the water to be treated is also improved. There is an advantage that it can take 5 times longer and the residence time in the contact tank can be shortened to 1/5 or less, but as mentioned above, the water depth of the ozone contact tank is 20-30 meters, which is feasible. Because it is longer, there is a problem that the construction work of the facility is more complicated than the diffuser pipe method, and furthermore, removal of deposits stored in the contact tank and cleaning of the tank cannot be easily performed, and the contact tank Even if any trouble occurs in the vicinity of the bottom of the body, it cannot be immediately treated.
[0014]
Here, considering the reaction process of ozone from another viewpoint, this ozone reaction process can be roughly divided into an initial stage in which the diffusion of ozone is rate-determined and a late stage in which the ozone reaction is rate-determined. Therefore, it is ideal that the gas-liquid reaction contact tank is also an apparatus based on these characteristics.For example, at the initial stage of the ozone reaction, it has a large contact area and a powerful stirring mechanism for increasing the diffusion efficiency, and the latter stage of the ozone reaction. It is sometimes desirable for the apparatus to ensure a residence time for obtaining a sufficient reaction.
[0015]
Considering the reaction processes of the two types of ozone contact tanks, it can be said that the U-tube type ozone contact tank is suitable at the initial stage of the ozone reaction, and the diffuser tube type ozone contact tank is suitable at the latter stage of the ozone reaction.
[0016]
According to Japanese Patent Application No. 8-42257, the present applicant has a pressurized vortex pump for gas-liquid mixing of water to be treated and ozone gas and a variable speed device for adjusting the amount of inflow water to be treated. The lower injection pipe in which the mixed water to be treated falls as a downward flow is discharged from a tip opening formed in a portion facing the bottom wall of the ozone contact tank, and an abrupt for adjusting the pressure in the pipe is formed near the tip opening. We have proposed a pressurized down-injection type ozone contact tank with a constricted part, but this time we have proposed a pressurized down-injection type multi-stage ozone contact tank for actual scales, so that the water to be treated can be treated without increasing the size of the special equipment. It is an object of the present invention to provide a pressurized down-injection type ozone contact tank and a method for controlling the same, in which the absorption efficiency of ozone gas with respect to water is increased and the absorption efficiency is not lowered with time.
[0017]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, according to claim 1, a branch pipe is provided in the middle of the inflow pipe for feeding the treated water into the upper and lower counter flow type multi-stage ozone contact tank. A first pressurized vortex pump for gas-liquid mixing of treated water and ozone gas and a rapid compression valve for adjusting the pressure in the output pipe of the first pressurized vortex pump are provided, and the output pipe is treated Secondly, the water to be treated and ozone gas are mixed in the branch pipe with gas-liquid mixture while being connected to a lower injection pipe inserted in the vertical direction in the first tank of the multi-stage ozone contact tank through the water supply pipe. The pressure eddy current pump and the rapid compression valve for adjusting the pressure in the output pipe of the second pressure vortex pump are provided, and the output pipe is inserted vertically into the second tank of the multi-stage ozone contact tank. A pressurized down-injection type multi-stage ozone contact tank connected to a lower infusion pipe arranged is provided.
[0018]
As a control method of the pressurized downward injection type multi-stage ozone contact tank, a treated water amount controller is disposed in the inflow pipe of the water to be treated in claim 2, and an ozone injection rate controller, an injected ozone concentration controller, and generated ozone are provided in the ozone generator. A densitometer is installed to determine the target value of the treated water volume from the treated water volume setting value and the treated water flow rate signal input to the treated water volume controller, and the ozone injection rate controller determines the treated water flow signal and the ozone injected rate. The injection ozone concentration target value is determined from the set value and output to the injection ozone concentration controller. The injection ozone concentration controller outputs a signal for controlling the driving state of the ozone generator based on the injection ozone concentration target value and the generated ozone concentration. By supplying ozone gas to the first and second pressurized vortex pumps, the ozone injection rate is And using a method for controlling.
[0019]
Further, according to claim 3, an exhaust ozone concentration controller, an injection ozone concentration controller and a generated ozone concentration meter are provided in the ozone generator, and an exhaust ozone concentration meter is provided in the multi-stage ozone contact tank, and the exhaust gas discharged from the contact tank is provided. The exhaust ozone concentration of the ozone gas is measured and input to the exhaust ozone concentration controller. The exhaust ozone concentration controller calculates the injection ozone concentration target value from the exhaust ozone concentration setting value and the exhaust ozone concentration signal, and outputs it to the injection ozone concentration. The ozone concentration controller outputs a signal for controlling the driving state of the ozone generator on the basis of the injected ozone concentration target value and the generated ozone concentration, and supplies ozone gas to the first and second pressurized vortex pumps to exhaust the ozone. A method of performing constant density control is used.
[0020]
The dissolved ozone concentration controller is used in place of the exhaust ozone concentration controller and a dissolved ozone concentration meter is provided in the multi-stage ozone contact tank, so that the dissolved ozone concentration is controlled constant, and the UV value is substituted for the exhaust ozone concentration controller. A controller is used and a low concentration UV meter is installed in a multi-stage ozone contact tank to realize a control method for performing constant UV absorbance control.
[0021]
In addition, the ozone generator is equipped with an injection ozone concentration controller and a generated ozone concentration meter, and an exhaust ozone concentration controller and an exhaust ozone concentration meter are installed in the multi-stage ozone contact tank, between the second pressurized vortex pump and the rapid compression valve. A pressure gauge and a rapid contraction valve opening controller are installed to measure the exhaust ozone concentration of the exhaust ozone gas discharged from the contact tank. At the same time, the pressure gauge measures the pressure between the second pressurized vortex pump and the rapid contraction valve. When the measured pressure value is within the specified range, the rapid contraction valve is made variable by the control output of the rapid contraction valve opening controller, and when the exhaust ozone concentration is high, the opening of the rapid contraction valve is decreased. Then, while increasing the pressure, when the exhaust ozone concentration is low, a method is proposed in which the pressure is reduced by increasing the opening of the rapid compression valve. Also, a method using a dissolved ozone concentration controller or a UV value controller in place of the exhaust ozone concentration controller is proposed.
[0022]
According to claim 9, a flock levitation separation tank is provided in the front stage portion of the multi-stage ozone contact tank, and an output pipe of a water pump for inflowing water to be treated is inserted vertically into the flock levitation separation tank. Provides a configuration of a pressurized down-injection type multi-stage ozone contact tank that is connected to a tube and provided with a flocculant inlet in the middle of the output tube to agglomerate soluble organic molecules and float and separate them as flocs To do.
[0023]
Of this floc floating separation tank Pressurized vortex pump in front part And an abrupt valve for adjusting the pressure in the pipe is provided in the middle of the output pipe of the pressurized vortex pump, and the other end of the output pipe is connected to the output pipe of the water pump. Multi-stage ozone contact that injects water containing fine bubbles into the water to be treated and simultaneously injects the flocculant from the flocculant inlet into the floc floating separation tank as a multiphase flow to generate micro flocs and floats It has a tank configuration.
[0024]
According to the pressurization type downward injection type ozone contact tank according to claim 1 and the control method according to claim 2, the water to be treated with ozone is supplied from the water supply pump through the branch pipe and then the first pressurization vortex pump. The ozone gas and the water to be treated injected into the ozone injection pipe are mixed and microbubbled by the first pressurized vortex pump to become high-concentration dissolved ozone water, and the pressure is adjusted by the rapid compression valve The treated water flowing in the output pipe is joined while being pumped through the output pipe, and the microbubble ozone gas and the treated water descend into the turbulent flow state while the gas-liquid is in contact with the lower injection pipe, resulting in the ozone gas and the treated water. Contact efficiency with water is increased. The treated water flowing into the first tank becomes an upward flow and overflows into the second tank.
[0025]
In parallel with this operation, the water to be treated in the branch pipe is also sent to the second pressurized vortex pump, and the injected ozone gas and water to be treated become high-concentration dissolved ozone water as described above. While the pressure-adjusted output tube is being pumped, the gas-liquid descends and contacts the lower injection tube arranged in the second tank of the multi-stage ozone contact tank. The treated water that has flowed into the second tank becomes an upward flow and overflows into the staying tank.
[0026]
The injected ozone concentration controller generates a control signal for the ozone generator based on the injected ozone concentration target value and the generated ozone concentration to control the driving state of the ozone generator, and the ozone gas generated from the ozone generator is the first and It is sent to the second pressurized vortex pump and the ozone injection rate constant control is performed. Thereafter, the exhaust ozone concentration constant control, the dissolved ozone concentration constant control, and the ultraviolet absorbance constant control are similarly performed.
[0027]
In addition, a floc floating separation tank, a third pressurized vortex pump, and a rapid contraction valve are installed in the front part of the multi-stage ozone contact tank, so that water containing fine bubbles generated by the action of the pressurized vortex pump is treated. Injected into water and injected with flocculant from the inlet, fine air bubbles and flocculant are mixed and flowed into the floc levitating separation tank as a multiphase flow, and micro flocs in the growth period are generated to generate floc levitating separation. It flows into the tank and floats and separates. By using ozone gas instead of air, the floc generating action is remarkably improved.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, various embodiments of a pressurized downward injection type multi-stage ozone contact tank and a control method thereof according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a first embodiment showing a basic configuration of a pressurized down-injection type multi-stage ozone contact tank corresponding to an actual scale used in the present invention, and 11 in the figure is a multi-stage ozone contact tank, The multi-stage ozone contact tank 11 includes a plurality of stages of a first tank 11a, a second tank 11b, and a staying tank 11c. Reference numeral 13 denotes an exhaust pipe for exhaust ozone gas. Therefore, the basic structure of the multi-stage ozone contact tank 11 is a vertical counter flow type.
[0029]
Reference numeral 15 denotes an inflow pipe for the water to be treated 20 fed into the multi-stage ozone contact tank 11, and the inflow pipe 15 is connected to the water feed pump 16, while a branch pipe 15 a connected to the middle part of the inflow pipe 15 is provided. The first pressurized vortex pump 17 is connected. An ozone injection pipe 18 for sending ozone gas from the ozone generator (not shown) into the water to be treated 20 is connected to the front stage of the first pressurized vortex pump 17. The pressurized vortex pump 17 has three functions of “mixing, microbubble formation, and pressure feeding” the ozone gas and the water 20 to be treated.
[0030]
In the middle of the output pipe 17a of the first pressurized vortex pump 17, a rapid compression valve 19 for adjusting the pressure in the output pipe 17a is provided. The rapid compression valve 19 is constituted by an orifice having a shape in which the diameter of the output pipe 17a is partially reduced to a small diameter.
[0031]
The other end of the output pipe 17a is connected to the output pipe 16a of the water pump 16. The output pipe 16a is a lower injection pipe 21 inserted and arranged in the first tank 11a of the multi-stage ozone contact tank 11 in the vertical direction. It is connected to. The tip opening of the lower injection tube 21 is introduced to a position near the bottom wall of the first tank 11a.
[0032]
On the other hand, the branch pipe 15 a of the inflow pipe 15 for the water to be treated 20 is also connected to the second pressurized vortex pump 22. An ozone injection pipe 23 for feeding ozone gas into 20 is connected. In the middle of the output pipe 22a of the second pressurized vortex pump 22, a rapid compression valve 24 for adjusting the pressure in the pipe is provided, and the other end of the output pipe 22a is the second stage of the multistage ozone contact tank 11. The two tanks 11b are connected to a lower injection pipe 25 inserted and arranged in the vertical direction. The tip opening of the lower injection tube 25 is introduced to a position near the bottom wall of the second tank 11b.
[0033]
The operation and principle of operation of the pressurized downward injection type multi-stage ozone contact tank 11 corresponding to the actual scale according to the first embodiment will be described below. First, as a basic operation, the water to be treated 20 to be ozone-treated is sent to the water pump 16 and at the same time, sent from the branch pipe 15a to the first pressurized vortex pump 17 and injected through the ozone injection pipe 18. The ozone gas and the water to be treated 20 are mixed and microbubbled by the impeller portion of the first pressurized vortex pump 17 to become high-concentration dissolved ozone water, and the inside of the output pipe 17a whose pressure is adjusted by the rapid compression valve 19 The water to be treated 20 that flows through the output pipe 16a of the water pump 16 while being pumped joins, and the ozone gas in the fine bubbles and the water to be treated 20 descend while the gas and liquid are in contact with each other in the lower injection pipe 21 to form the first tank. It hits the bottom wall of 11a and becomes a turbulent state. As a result, the contact efficiency between the ozone gas and the water to be treated 20 is increased.
[0034]
By setting the flow rate of the output pipe 16a of the water pump 16 to 2 (m / sec) or less, the effect of staying in the pipe (abbreviated as hold-up) is produced and the ozone gas dissolving action is enhanced. Moreover, the to-be-processed water 20 which flowed in in the 1st tank 11a becomes an upward flow, and overflows into the 2nd tank 11b.
[0035]
In parallel with the above operation, the water to be treated 20 in the branch pipe 15a is sent to the second pressurized vortex pump 22, and the ozone gas and the water to be treated 20 injected through the ozone injection pipe 23 are the same as described above. The multi-stage ozone contact tank 11 is mixed and microbubbled by the impeller portion of the second pressurized vortex pump 22 to become high-concentration dissolved ozone water, and is pumped through the output pipe 22a whose pressure is adjusted by the rapid contraction valve 24. In the lower injection pipe 25 arranged in the second tank 11b, the gas-liquid descends in contact with each other, hits the bottom wall, and becomes a turbulent state. The treated water 20 that has flowed into the second tank 11b becomes an upward flow and overflows the retention tank 11c.
[0036]
The treated water 20 mixed with ozone gas in this way flows from the lower side to the upper side of the first tank 11a, the second tank 11b, and the retention tank 11c constituting the multi-stage ozone contact tank 11, and has a predetermined residence time. After that, it flows out as ozone treated water 10 and is temporarily stored in an ozone treated water tank (not shown) to prepare for the next step. Unreacted ozone gas is sent from the discharge pipe 13 to an exhaust ozone treatment device (not shown), and is decomposed into harmless gas by known thermal decomposition, decomposition using a catalyst, soil decomposition, chemical cleaning treatment or activated carbon treatment in the atmosphere. To be released. That is, ozone gas has a strong oxidizing power similar to that of fluorine and is a harmful substance to the human body, so that it is indispensable to decompose it with an exhaust ozone treatment device.
[0037]
By such contact between the ozone gas and the water 20 to be treated, deodorization, decolorization, ferromanganese, polycyclic compounds and organic substances are removed by oxidation, sterilization, algaecidal and off-flavor removal.
[0038]
During the above operation, the ratio of the flow rate of water to be treated / ozone gas flow rate (abbreviated as L / G ratio) by driving the first and second pressurized vortex pumps 17 and 22 is 5 or more, and the pressure in the pipe is 1.5. (Kgf / cm ² ) It is necessary to do more. That is, FIG. 2 is a graph showing the relationship between dissolved ozone concentration (mg / l) and residence time (min) when the pressure P in the pipe is changed, and FIG. 3 is dissolved when the L / G ratio is changed. It is a graph which shows the relationship between ozone concentration and residence time. In the figure, η is ozone absorption efficiency (%).
[0039]
When the ozone injection rate is constant from FIG. 2, when the pipe pressure P is increased, the dissolved ozone concentration is also increased, and from FIG. 3, the dissolved ozone concentration is increased when the L / G ratio is decreased. Therefore, it can be seen that a high concentration of dissolved ozone water can be obtained under high pressure. The maximum pressure in the tube is 4.0 (kgf / cm from the viewpoint of energy cost. ² ) Is reasonable.
[0040]
The ratio of the amount of water to be treated 20 to the amount of water flow of the first and second pressurized vortex pumps 17 and 22 (abbreviated as Lm / Lk) is the maximum dissolved ozone concentration target value in the multi-stage ozone contact tank 11. Although it depends, if the maximum dissolved ozone concentration is about 0.5 (mg / l), it is appropriate to set Lm / Lk in the range of 15-30. Therefore, the injection rate of the pressurized vortex pumps 17 and 22 is about 8 to 16 (mg / l) when the ozone absorption efficiency η is 95%.
[0041]
Next, a control example 1 in this embodiment will be described with reference to FIG. Since the basic configuration of the apparatus itself is the same as that of the first embodiment shown in FIG. 1, the same reference numerals are given in the drawing.
[0042]
In this control example 1, the pressure of the first and second pressurized vortex pumps 17 and 22 is kept constant and the ozone injection rate is changed. In the figure, 27 is a treated water amount controller, 28 is an ozone injection rate controller, 29 is an injection ozone concentration controller, 30 is an exhaust ozone concentration meter, 31 is an ozone generator, 32 is a generated ozone concentration meter, 33 is an exhaust ozone decomposition device, 34 and 35 are pressure gauges, 36, 37, 38, 39, 40 and 41 are flow meters, 42 is a blower, and 43 is a dissolved ozone concentration meter.
[0043]
According to the control example 1, the treated water 20 is branched into the first and second pressurized vortex pumps 17 and 22 as described above. The total amount of water flow of 16 is consistent with the overall throughput. Further, the rotation speeds of the first and second pressurized vortex pumps 17 and 22 are not changed, and the ozone gas flow rate to both the pressurized vortex pumps 17 and 22 is not changed as a constant amount. Accordingly, the L / G ratio of both the pressurized vortex pumps 17 and 22 is also constant, and only the injection ozone gas concentration is variably controlled.
[0044]
More specifically, the treated water amount controller 27 receives the treated water amount set value 44 and the flow signal of the treated water 20 measured by the flow meter 38, and the treated water amount target value 45 output from the treated water amount controller 27. Is input to the water pump 16. Further, the flow rate signal of the water to be treated 20 measured by the flow meter 38 is input to the ozone injection rate controller 28. The ozone injection rate controller 28 calculates the injected ozone concentration from the ozone injection rate set value 46 and the flow rate signal of the water to be treated. A target value 47 is obtained and output to the injected ozone concentration controller 29.
[0045]
The injected ozone concentration controller 29 issues a control signal 48 to the ozone generator 31 based on the injected ozone concentration target value 47 and the generated ozone concentration meter 32 obtained from the generated ozone concentration meter 32 to control the driving state of the ozone generator 31. The The normal control signal 48 is input as an electric power value to the ozone generator 31, and ozone gas generated from the ozone generator 31 passes through the ozone injection pipes 18 and 23 to the first and second pressurized vortex pumps 17 and 22. It is sent. The amount of ozone gas generated from the ozone generator 31 is measured by the flow meter 40 and fed back to the generated ozone concentration meter. The dissolved ozone concentration meter 43 provided in the staying tank 11c measures and monitors the dissolved ozone concentration after the ozone treatment. Therefore, this control example 1 is basically based on a constant ozone injection rate control.
[0046]
The exhaust ozone gas discharged from the exhaust ozone gas discharge pipe 13 is led to the exhaust ozone concentration meter 30 through the flow meter 39 to measure the exhaust ozone concentration, and the exhaust ozone decomposition device 33 is driven by the drive of the blower 42. It is sent and disassembled.
[0047]
This control example 1 is controlled by the flow rate of the water to be treated, the ozone injection rate, and the ozone concentration controller, detects fluctuations in the water supply amount and setting changes based on the signal from the flow meter 38, and performs comparison calculation processing with the set value. This is characterized in that the ozone injection rate is variably controlled by performing the above. If the ozone injection rate is D,
D = aX ± b (1)
It becomes. Here, a is a setting coefficient and b is a correction coefficient.
[0048]
Next, a control example 2 in this embodiment will be described with reference to FIG. In this control example 2, the exhaust ozone concentration controller 50 is used instead of the ozone injection rate controller 28 in the control example 1, and the treated water amount controller 27 is not installed. Other configurations are the same as those in the control example 1.
[0049]
In this control example 2, the exhaust ozone concentration is basically constant, and the exhaust ozone gas discharged from the exhaust ozone gas discharge pipe 13 is guided to the exhaust ozone concentration meter 30 through the flow meter 39 to measure the exhaust ozone concentration. An exhaust ozone concentration signal 51 is input to the exhaust ozone concentration controller 50. The exhaust ozone concentration controller 50 obtains an injection ozone concentration target value 47 from the exhaust ozone concentration set value 52 and the exhaust ozone concentration signal 51 and outputs it to the injection ozone concentration controller 29. The injected ozone concentration controller 29 generates a control signal 48 for the ozone generator 31 based on the injected ozone concentration target value 47 and the generated ozone concentration obtained from the generated ozone concentration meter 32 to control the driving state of the ozone generator 31. . Other control modes are the same as in Control Example 1.
[0050]
Next, the control example 3 in a present Example is demonstrated. Although not shown in the control example 3, the feature is that a dissolved ozone concentration controller is used instead of the exhaust ozone concentration controller 50 in the control example 2. Other configurations are the same as those of the control example 2.
[0051]
In this control example 3, the dissolved ozone concentration is basically constant, the dissolved ozone concentration after the ozone treatment is measured by the dissolved ozone concentration meter 43 provided in the staying tank 11c, and this dissolved ozone concentration is fed back to the dissolved ozone concentration controller. The The dissolved ozone concentration controller obtains the injected ozone concentration target value from the preset dissolved ozone concentration setting value and the measured dissolved ozone concentration signal, and outputs it to the injected ozone concentration controller. Based on the generated ozone concentration obtained from 32, a control signal 48 for the ozone generator 31 is issued to control the driving state of the ozone generator 31.
[0052]
Next, the control example 4 in a present Example is demonstrated. Although not shown in this control example 4, instead of the dissolved ozone concentration controller in the control example 3, a UV value controller is adopted, and instead of the dissolved ozone concentration meter 43 provided in the retention tank 11c, a low concentration UV meter is used. It is characterized by having deployed. Other configurations are the same as those of the control example 3.
[0053]
In this control example 4, the UV value (ultraviolet light absorbance) is basically constant, the UV value after ozone treatment is measured by the UV meter provided in the staying tank 11c, and this UV value is fed back to the UV value controller. The UV value controller obtains the injection ozone concentration target value from the preset UV setting value and the measured UV value signal and outputs it to the injection ozone concentration controller, and is obtained from the generated ozone concentration meter 32 as in the control example 2. Based on the generated ozone concentration, a control signal 48 is issued to the ozone generator 31 to control the driving state of the ozone generator 31.
[0054]
Next, a control example 5 in this embodiment will be described with reference to FIG. In the figure, 50 is an exhaust ozone concentration controller, 53 is a pressure gauge disposed between the second pressurized vortex pump 22 and the rapid contraction valve 24, and 54 is a rapid contraction valve opening controller. A newly provided valve opening controller 54 is a structural feature of Control Example 5.
[0055]
According to the control example 5, the exhaust ozone gas discharged from the exhaust ozone gas discharge pipe 13 is guided to the exhaust ozone concentration meter 30 through the flow meter 39 and the exhaust ozone concentration is measured. The pressure between the second pressurized vortex pump 22 and the rapid compression valve 24 is measured, and each measured value is input to the determination means 100. The pressure value P is within a predetermined range, for example, 2 (kgf / cm ² ) <P <4 (kgf / cm ² ) Is within the range (YES), the rapid contraction valve 24 is made variable by the control output of the rapid contraction valve opening controller 54, and when the exhaust ozone concentration measured by the exhaust ozone concentration meter 30 is high, While the pressure P is increased by decreasing the opening of the valve 24, the pressure P is decreased by increasing the opening of the rapid valve 24 when the exhaust ozone concentration is low.
[0056]
When the measured value of the pressure gauge 53 is outside the predetermined range (No), the exhaust ozone concentration controller 50 obtains the injected ozone concentration target value 47 from the exhaust ozone concentration set value 52 and the signal from the determination means 100. The injected ozone concentration controller 29 outputs the control signal 48 to the ozone generator 31 based on the injected ozone concentration target value 47 and the generated ozone concentration obtained from the generated ozone concentration meter 32 to generate the ozone. The driving state of the device 31 is controlled.
[0057]
In this control example 5, simultaneously with the measurement of the exhaust ozone concentration, the pressure state between the second pressurized vortex pump 22 and the rapid compression valve 24 is measured by the pressure gauge 53, and the rapid compression valve 24 is variably controlled. It is a feature.
[0058]
Next, a control example 6 in the present embodiment will be described. In the case of this control example 6, although not shown, a feature is that a dissolved ozone concentration controller is provided in place of the exhaust ozone concentration controller 50 of the control example 5. Other configurations are substantially the same as those in the control example 5.
[0059]
According to the sixth control example, the pressure gauge 53 is measured simultaneously with the measurement value of the dissolved ozone concentration meter 43 installed in the retention tank 11c in consideration that the dissolved ozone concentration also changes with the change in pressure. Is used to measure the pressure between the second pressurized vortex pump 22 and the rapid compression valve 24, and each measured value is input to the determination means 100, and the pressure value P is within a predetermined range, for example 2 (Kgf / cm ² ) <P <4 (kgf / cm ² ) Is within the range (YES), the rapid contraction valve 24 is made variable by the control output of the rapid contraction valve opening controller 54, and when the dissolved ozone concentration measured by the dissolved ozone concentration meter 43 is high, While the pressure P is decreased by increasing the opening of the valve 24, the pressure P is increased by decreasing the opening of the rapid valve 24 when the dissolved ozone concentration is low. When the measured value of the pressure gauge 53 is outside the predetermined range (No), the dissolved ozone concentration controller obtains the injected ozone concentration target value 47 from the dissolved ozone concentration set value and the signal from the determination means 100. Based on the target ozone concentration 47 and the generated ozone concentration obtained from the generated ozone concentration meter 32, the control signal 48 is sent to the ozone generating device 31 and the driving state of the ozone generating device 31 is output. Be controlled.
[0060]
FIG. 7 is a graph showing the correlation between the residence time when the pressure is changed and the residual rate (Co / Ci) of E260 (ultraviolet light absorbance at a wavelength of 260 nm), which is an indicator of organic matter. The removal rate also changes proportionally. Using this characteristic, the following control example 7 was realized.
[0061]
In the case of this control example 7, although not shown in the figure, a UV value controller is provided instead of the dissolved ozone concentration controller of control example 6, and a low concentration UV meter is substituted for the staying tank 11c instead of the dissolved ozone concentration meter 43. It is characterized by having deployed. Other configurations are the same as those in the control examples 5 and 6.
[0062]
According to the control example 7, the pressure between the second pressurized vortex pump 22 and the rapid compression valve 24 is measured by the pressure gauge 53 simultaneously with the measurement of the E260 absorbance by the UV meter installed in the staying tank 11c. Each measurement value is input to the determination means 100. This pressure value P is within a predetermined range, for example, 2 (kgf / cm ² ) <P <4 (kgf / cm ² ) Is within the range (YES), the rapid contraction valve 24 is made variable by the control output of the rapid contraction valve opening controller 54, and when the E260 absorbance measured by the UV meter is high, the rapid contraction valve 24 While the opening degree is increased and the pressure P is decreased, when the E260 absorbance is low, the opening degree of the rapid compression valve 24 is decreased and the pressure P is increased. If the measured value of the pressure gauge 53 is outside the predetermined range (No), the UV value controller obtains the target ozone concentration for injection from the UV set value and the signal from the determination means 100, and the control example 6 The control signal 48 is output to the injected ozone concentration controller 29 and the control signal 48 for the ozone generator 31 is generated based on the injected ozone concentration target value 47 and the generated ozone concentration obtained from the generated ozone concentration meter 32. The driving state is controlled.
[0063]
FIG. 8 is a schematic view of a second embodiment of a pressurized down-injection type multi-stage ozone contact tank corresponding to an actual scale used in the present invention. The same components as those of the first embodiment shown in FIG. The same reference numerals are attached and displayed.
[0064]
In the second embodiment, a floc levitating separation tank 60 for the purpose of coagulation and separation is arranged in the front stage portion of the multi-stage ozone contact tank 11 disclosed in the first embodiment. Reference numeral 61 denotes a water supply pump for flowing the water to be treated 20 into the floc levitation separation tank 60. An output pipe 61 a of the water pump 61 is a lower injection pipe 65 inserted and arranged in the floc levitation separation tank 60 in the vertical direction. It is connected to. A coagulant inlet 64 is provided in the middle of the output pipe 61a.
[0065]
62 is a third pressurizing vortex pump, 63 is a rapid compression valve for adjusting the pressure in the pipe disposed in the middle of the output pipe 62a of the third pressurizing vortex pump 62, and the other end of the output pipe 62a is It is connected to the output pipe 61a of the water pump 61.
[0066]
An injection pipe 66 for sending air or ozone gas into the water is connected to the front stage of the third pressurized vortex pump 62. The third pressurized vortex pump 62 is connected to a pipe 67 led out from the retention tank 11c of the ozone multi-stage contact tank 11, and the treated water once ozone-treated is reused for mixing ozone gas and water. in use. The pipe 68 led out from the retention tank 11c is also connected to the first and second pressurized vortex pumps 17 and 22.
[0067]
A rotary scraper 70 and a scraper 71 are provided in the vicinity of the water surface portion of the floc floating separation tank 60, and exhaust ozone gas or air is discharged to a lid member 72 that covers the upper surface of the floc floating separation tank 60. An outlet 73 is opened.
[0068]
The configuration of the multi-stage ozone contact tank 11 and the arrangement of the first and second pressurized vortex pumps 17 and 22 and the rapid compression valves 19 and 24 are basically the same as those in the first embodiment. Avoid duplication.
[0069]
The operation | movement at the time of the driving | operation of the pressurization type downward injection type multistage ozone contact tank 11 of this 2nd Example is demonstrated below. First, when air is used as the gas to be injected into the injection pipe 66, water containing fine bubbles generated by the action of the third pressurized vortex pump 62 and the rapid contraction valve 63 flows in the output pipe 61a of the water supply pump 61. By injecting the flocculant into the water to be treated 20 and simultaneously injecting the flocculant from the inlet 64 that is opened in the middle of the output pipe 61a, the microbubble air and the flocculant are mixed in the output pipe 61a and mixed phase flow. And flows into the floc floating separation tank 60.
[0070]
Then, micro-floc during the growth period is generated in the water 20 to be treated by the fine bubble air and the flocculant, and flows into the floc floating separation tank 60 from the lower injection pipe 65 inserted and arranged in the vertical direction. At this time, fine bubbles of air adhere to the flocs of several tens of microns and act to reduce the apparent density of the micro flocs.
[0071]
The micro floc to which fine bubbles are attached floats in the floc floating separation tank 60, is scraped by a rotary scraper 70 provided in the vicinity of the water surface, is scraped by a scraper 71 and is discharged out of the system. Is done.
[0072]
Thus, the water to be treated from which the floc has been removed in the floc floating separation tank 60 is sent to the first tank 11a of the ozone multi-stage contact tank 11, and the first and second pressurization as described in the first embodiment below. The desired ozone treatment is performed in accordance with the action of the vortex pumps 17 and 22 and the rapid compression valves 19 and 24.
[0073]
Next, a third embodiment of the present invention will be described. The third embodiment is characterized in that ozone gas is used as the gas injected into the injection pipe 66 of the second embodiment shown in FIG.
[0074]
The following items can be considered as factors for improving the floc cohesion by the flocculant. That is,
(1) Low molecular weight organic polymer materials
(2) Aggregation and precipitation of soluble organic molecules
(3) Increased polarity of organic molecules
(3) further includes conversion of organic substances into polyelectrolytes, improvement in adsorptivity to floating substances, and an increase in the chemical crosslinking function between the colloid of viscosity and micro flocs by chemical aggregation.
[0075]
And ozone gas and dissolved ozone have the effect | action which carries out an oxidation reaction with a soluble organic molecule | numerator, and becomes low molecule, and reduces disinfection by-product substance.
[0076]
Therefore, in the third embodiment, ozone gas is used as the gas to be injected into the injection pipe 66, so that floc coagulation due to the coagulant injected from the injection port 64 is improved, and the subsequent ozone contact effect can be enhanced.
[0077]
【The invention's effect】
As described in detail above, according to the pressurized downward injection type multi-stage ozone contact tank and the control method thereof according to the present invention, the first pressurized vortex pump after the water to be treated with ozone passes through the branch pipe It is mixed and microbubbled with the injected ozone gas to become high-concentration dissolved ozone water. The contact efficiency can be increased by lowering the water to be treated while the gas and liquid are in contact with the lower injection pipe, so that the same treatment characteristics can be achieved with a residence time shorter than the residence time of the conventional aeration tube type ozone contact tank. Obtainable.
[0078]
Further, in parallel with the above operation, the water to be treated in the branch pipe is also sent to the second pressurized vortex pump, and the injected ozone gas and the water to be treated become high-concentration dissolved ozone water in the same manner as described above. Thus, the ozone treatment efficiency is increased by being fed into the second tank of the multi-stage ozone contact tank while being fed through the output pipe whose pressure has been adjusted.
[0079]
The injection ozone concentration controller controls the driving state of the ozone generator based on the injection ozone concentration target value and the generated ozone concentration, and the ozone injection rate is constant when the generated ozone gas is sent to the first and second pressurized vortex pumps. Control of exhaust ozone concentration, control of dissolved ozone concentration, control of UV absorbance, and control of UV absorbance are possible. At the initial stage of the ozone reaction, the diffusion efficiency is sufficiently increased based on the downward injection method. Higher substances are removed, and this accelerates the reaction process in the initial stage in which the diffusion of ozone gas is controlled, and at the later stage of the ozone reaction, the removal of less reactive substances is performed even with a short residence time. The effect is that the late-stage reaction that is rate-limiting is promoted.
[0080]
In addition, a floc floating separation tank, a third pressurized vortex pump, and a rapid contraction valve are arranged in the front stage of the multi-stage ozone contact tank, so that fine bubble air and The flocculant is mixed and flows into the floc floating separation tank, and the growing micro floc can be floated and separated in the floc floating separation tank. Especially, the use of ozone gas instead of air makes the floc generation action remarkably. Can be increased.
[0081]
Further, in the case of a conventional deep U-tube type ozone contact tank, the treatment characteristics vary when the water flow rate fluctuates. On the other hand, according to the control example of this embodiment, a stable treatment characteristic is obtained. Optimal ozone injection rate control corresponding to water volume fluctuations becomes possible. Further, by performing the exhaust ozone concentration constant control, the dissolved ozone concentration constant control, and the ultraviolet absorbance constant control, an effect that the time to reach the target water quality is shortened compared to the diffuser system can be obtained.
[0082]
Since the multi-stage ozone contact tank according to the present embodiment does not have to be formed to a length of 20 to 30 meters like a conventional U-tube reaction tank, absorption of ozone gas to the water to be treated without increasing the size of the apparatus. Efficiency can be increased. Further, it is possible to prevent the absorption efficiency from decreasing with time due to clogging due to adhesion of iron or manganese oxidized by ozone gas.
[0083]
Furthermore, there is no problem that the construction work of the facility is complicated like the U tube type ozone reaction tank, the construction cost can be reduced, and the removal of deposits stored in the reaction tank and the cleaning in the tank are simple. In addition, there is an effect that even if a failure occurs near the bottom of the reaction tank, it can be immediately treated.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing the overall configuration of a first embodiment of a pressurized downward injection type multi-stage ozone contact tank according to the present invention.
FIG. 2 is a graph showing the relationship between dissolved ozone concentration and residence time when the pressure in the tube is changed.
FIG. 3 is a graph showing the relationship between dissolved ozone concentration and residence time when the L / G ratio is changed.
FIG. 4 is a schematic diagram for explaining a control example 1 in the embodiment.
FIG. 5 is a schematic diagram for explaining a control example 2 in the embodiment.
FIG. 6 is a schematic diagram for explaining a control example 5 in the present embodiment.
FIG. 7 is a graph showing the correlation between the residence time and the E260 residual rate when the pressure is changed.
FIG. 8 is a schematic view showing the whole of a second embodiment of a pressurized downward injection type multi-stage ozone contact tank according to the present invention.
FIG. 9 is a sectional view of an essential part showing an example of a normal diffuser-type ozone reaction tank.
FIG. 10 is a schematic view showing the structure of a normal U tube type ozone contact tank.
[Explanation of symbols]
11 ... Multi-stage ozone contact tank
11a ... first tank
11b ... 2nd tank
13 ... (exhaust ozone gas) discharge pipe
15 ... Inflow pipe (to-be-treated water)
16, 61 ... water pump
17 ... First pressurized vortex pump
18, 23 ... Ozone injection tube
19, 24, 63 ... Rapid valve
20 ... treated water
21, 25, 65 ... Downward injection pipe
22 ... Second pressurized vortex pump
27 ... treated water volume controller
28 ... Ozone injection rate controller
29 ... Injection ozone concentration controller
30 ... Exhaust ozone concentration meter
31 ... Ozone generator
32 ... Generated ozone concentration meter
33 ... Waste ozone decomposition device
34, 35.53 ... Pressure gauge
43 ... Dissolved ozone meter
50 ... Exhaust ozone concentration controller
54 ... Rapid compression valve opening controller
60 ... Floc floating separation tank
62 ... Third pressurized vortex pump
70 ... Scratching machine
71 ... scraper

Claims (9)

  A first pressurized vortex pump for providing a branch pipe in the middle of the inflow pipe for feeding the water to be treated to the upper and lower counter flow type multi-stage ozone contact tank, and mixing the water to be treated and ozone gas in the branch pipe; A rapid compression valve for adjusting the pressure in the output pipe of the first pressurized vortex pump is provided, and the output pipe is vertically connected to the first tank of the multi-stage ozone contact tank through the water supply pipe of the water to be treated. A second pressurized vortex pump for gas-liquid mixing of the water to be treated and ozone gas, and an output pipe of the second pressurized vortex pump. A pressurization type downward injection characterized in that a rapid compression valve for adjusting the pressure is provided, and the output pipe is connected to a lower injection pipe that is vertically inserted in the second tank of the multi-stage ozone contact tank. Multi-stage ozone contact tank. A first pressurized vortex pump for providing a branch pipe in the middle of the inflow pipe for feeding the water to be treated to the upper and lower counter flow type multi-stage ozone contact tank, and mixing the water to be treated and ozone gas in the branch pipe; A rapid compression valve for adjusting the pressure in the output pipe of the first pressurized vortex pump is provided, and the output pipe is vertically connected to the first tank of the multi-stage ozone contact tank through the water supply pipe of the water to be treated. A second pressurized vortex pump for gas-liquid mixing of the water to be treated and ozone gas, and an output pipe of the second pressurized vortex pump. A pressurization type lower injection type multistage ozone contact tank in which a rapid compression valve for adjusting the pressure is provided and the output pipe is connected to a lower injection pipe inserted in the vertical direction in the second tank of the multistage ozone contact tank. In
A treated water amount controller is disposed in the inflow pipe of the treated water, and an ozone injection rate controller, an injected ozone concentration controller and a generated ozone concentration meter are disposed in the ozone generator, and the treated water amount set value input to the treated water amount controller The treated water volume target value is determined from the flow signal of the treated water, and the ozone injection rate controller determines the injected ozone concentration target value from the treated water flow signal and the ozone injection rate set value and outputs it to the injected ozone concentration controller. The injected ozone concentration controller outputs a signal for controlling the driving state of the ozone generator based on the injected ozone concentration target value and the generated ozone concentration, and supplies ozone gas to the first and second pressurized vortex pumps. Control method of pressurized bottom injection type multi-stage ozone contact tank, characterized by performing constant control of ozone injection rate by means of A first pressurized vortex pump for providing a branch pipe in the middle of the inflow pipe for feeding the water to be treated to the upper and lower counter flow type multi-stage ozone contact tank, and mixing the water to be treated and ozone gas in the branch pipe; A rapid compression valve for adjusting the pressure in the output pipe of the first pressurized vortex pump is provided, and the output pipe is vertically connected to the first tank of the multi-stage ozone contact tank through the water supply pipe of the water to be treated. A second pressurized vortex pump for gas-liquid mixing of the water to be treated and ozone gas, and an output pipe of the second pressurized vortex pump. A pressurization type lower injection type multistage ozone contact tank in which a rapid compression valve for adjusting the pressure is provided and the output pipe is connected to a lower injection pipe inserted in the vertical direction in the second tank of the multistage ozone contact tank. In
An exhaust ozone concentration controller, an injection ozone concentration controller, and a generated ozone concentration meter are installed in the ozone generator, and an exhaust ozone concentration meter is installed in the multi-stage ozone contact tank to reduce the exhaust ozone concentration of the exhaust ozone gas discharged from the contact tank. Measurement and input to the exhaust ozone concentration controller, the exhaust ozone concentration controller obtains the injection ozone concentration target value from the exhaust ozone concentration set value and the exhaust ozone concentration signal and outputs it to the injection ozone concentration, and the injection ozone concentration controller Based on the concentration target value and the generated ozone concentration, a signal for controlling the driving state of the ozone generator is output, and ozone gas is supplied to the first and second pressurized vortex pumps to perform exhaust ozone concentration constant control. A control method for a pressurization type downward injection type multi-stage ozone contact tank.   The dissolved ozone concentration constant control is performed by using a dissolved ozone concentration controller instead of the exhaust ozone concentration controller and disposing a dissolved ozone concentration meter in a multistage ozone contact tank. Control method of pressure type downward injection type multi-stage ozone contact tank.   4. The pressurization type lower part according to claim 2, wherein a UV value controller is used in place of the exhaust ozone concentration controller, and a low concentration UV meter is provided in a multi-stage ozone contact tank, whereby the UV absorbance constant control is performed. Control method of injection type multi-stage ozone contact tank. A first pressurized vortex pump for providing a branch pipe in the middle of the inflow pipe for feeding the water to be treated to the upper and lower counter flow type multi-stage ozone contact tank, and mixing the water to be treated and ozone gas in the branch pipe; A rapid compression valve for adjusting the pressure in the output pipe of the first pressurized vortex pump is provided, and the output pipe is vertically connected to the first tank of the multi-stage ozone contact tank through the water supply pipe of the water to be treated. A second pressurized vortex pump for gas-liquid mixing of the water to be treated and ozone gas, and an output pipe of the second pressurized vortex pump. A pressurization type lower injection type multistage ozone contact tank in which a rapid compression valve for adjusting the pressure is provided and the output pipe is connected to a lower injection pipe inserted in the vertical direction in the second tank of the multistage ozone contact tank. In
The ozone generator is equipped with an injection ozone concentration controller and a generated ozone concentration meter, and an exhaust ozone concentration controller and an exhaust ozone concentration meter are disposed in a multi-stage ozone contact tank, and further between the second pressurized vortex pump and the rapid contraction valve. A pressure gauge and a rapid contraction valve opening controller are installed to measure the exhaust ozone concentration of the exhaust ozone gas discharged from the contact tank. At the same time, the pressure gauge measures the pressure between the second pressurized vortex pump and the rapid contraction valve. When the measured pressure value is within the specified range, the rapid contraction valve is made variable by the control output of the rapid contraction valve opening controller, and when the exhaust ozone concentration is high, the opening of the rapid contraction valve is decreased. And controlling the pressurization type downward injection type multi-stage ozone contact tank to increase the pressure while reducing the pressure by increasing the opening of the rapid compression valve when the exhaust ozone concentration is low .   A dissolved ozone concentration controller is used instead of the exhaust ozone concentration controller, and a dissolved ozone concentration meter is provided in the multi-stage ozone contact tank, and at the same time as measuring the dissolved ozone concentration in the contact tank, a second pressurized eddy current pump is used by the pressure gauge. When the pressure is within the specified range, if the dissolved ozone concentration is high after changing the rapid contraction valve by the control output of the rapid contraction valve opening controller 7. The pressure is reduced by increasing the opening of the rapid contraction valve, and when the dissolved ozone concentration is low, control is performed to increase the pressure by decreasing the opening of the rapid contraction valve. Control method for pressurized type bottom injection type multi-stage ozone contact tank.   A UV value controller is used in place of the exhaust ozone concentration controller, and a low concentration UV meter is provided in the multi-stage ozone contact tank, and at the same time the UV value of the contact tank is measured, When the pressure between the valves is measured and the pressure value is within a predetermined range, the E260 absorbance measured by the UV meter is high after making the valve suddenly variable by the control output of the valve opening controller. In this case, the pressure is decreased by increasing the opening degree of the rapid contraction valve, and when the E260 absorbance is low, control is performed to increase the pressure by decreasing the opening degree of the rapid contraction valve. The control method of the pressurization type downward injection type multistage ozone contact tank of 6 and 7. A floc floating separation tank is installed in the front stage of the multi-stage ozone contact tank, and the output pipe of the water pump for inflowing water to be treated is connected to the lower injection pipe inserted vertically in the floc floating separation tank. A pressurization type downward injection type multi-stage ozone contact tank characterized in that a flocculant injection port is provided in the middle of the output pipe so that soluble organic molecules are aggregated and floated and separated as a floc ,
A pressurized vortex pump is provided in the front part of the floc floating separation tank, and a rapid compression valve for adjusting the pressure in the pipe is provided in the middle of the output pipe of the pressurized vortex pump, and the other end of the output pipe is supplied with water. By connecting to the output pipe of the pump, water containing fine bubbles of air or ozone gas is injected into the water to be treated, and at the same time, the flocculant is injected from the inlet of the flocculant to flow into the floc floating separation tank as a multiphase flow. A pressurization type downward injection type multi-stage ozone contact tank characterized in that a micro floc is formed and floated and separated.

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