JPH07232158A - Device for controlling amount of ozone generation - Google Patents

Abstract

PURPOSE:To provide a device by which the operation of an ozone-treating vessel using an optimum ozone injection rate in order to secure the target water quality can be performed at the time of subjecting feed water such as sewage secondary-treated water, etc., to ozone treatment. CONSTITUTION:In the ozone treating device, the sterilization, deodorization and decoloration of the feed water 2 that flows into the closed type ozone- treating vessel 1 are performed by diffusing gaseous ozone from the ozone generator 3 into the feed water 2 to utilize the oxidizing and sterilizing power of ozone. At the same time, the ozone treating device is provided with the absorption efficiency controller 6 to calculate the target value 10 of the ozone concn. to be injected by using the gaseous ozone absorption efficiency inputted to the controller 6 and the absorption efficiency set value 9 set beforehand and to control the operating conditions of the ozone generator 3 based on this target value 10 of the ozone concn. to be injected. The gaseous ozone absorption efficiency is determined by using the ozone concn. injected into the ozone- treating vessel 1 and the ozone concn. discharged from the vessel 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ozone generation amount control device in an ozone treatment device mainly used for sewage treatment.

[0002]

2. Description of the Related Art Generally, in order to purify raw water taken from rivers or secondary treated water of sewage, a coagulant is injected and mixed in raw water in a coagulating sedimentation tank, and suspended substances in the raw water are treated by stirring and retaining. (Sand, clay, algae, and other organic matter) are aggregated, precipitated, and separated. This process incorporates chlorine treatment for the purpose of algicidal treatment and removal of chromaticity components.

[0003] On the other hand, with the increasing prevalence of sewerage in recent years, effective utilization of sewage treated water is expected as a water resource in urban areas. In particular, treated sewage water, which is said to exceed 8 billion m ³ annually, has the potential as a stable water resource in urban areas, and there are expectations for reuse of treated water in various forms. One of them is reuse for landscape water or hydrophilic water.

As a form of reuse as scenic water, it can be considered that the treated water is introduced into an existing waterway, the water is used as water retention such as a moat, or introduced into an artificial waterway. Further, hydrophilic water is reused water that is presumed to be touched by humans such as playing in water.

As described above, in order to reuse the treated sewage water as scenic water / hydrophilic water, sufficient consideration is given to hygienic safety of the reused water, sensory comfort, reuse technology, and complementary measures. Need to do.

In order to reuse the treated sewage water, the basic water quality items to be noted are, in addition to the treated water quality required for the treated sewage water up to now, the removal of the number of coliform bacteria, odor and chromaticity. It becomes a problem. In particular, the ozone treatment method is suitable for removing the above-mentioned Escherichia coli, odor and chromaticity. That is, ozone has a strong oxidizing power and sterilizing power, and can effectively sterilize, deodorize and decolorize as compared with other methods. Especially in the field of water purification, THM (trihalomethane) caused by chlorine treatment
Ozone treatment has recently been put into practical use for the purpose of countermeasures and countermeasures against deterioration of raw water quality.

Against this background, as an alternative to chlorine treatment for the purpose of removing the above-mentioned substances, ozone treatment is performed by an ozone treatment tower to remove chromaticity components and the like, and then a biological filtration tower is used to adsorb ammonia and organic substances. After that, a method of filtering the water with a sand filter and sending it to the water purification tank is being adopted. In particular, by performing the ozone treatment before the biological activated carbon treatment, it is possible to improve the tolerance for load fluctuation and the life of the activated carbon.

[0008]

However, as the conventional ozone treatment control, normal ozone emission amount is proportional to treated water amount, or injected ozone concentration and dissolved ozone concentration are kept constant or exhaust ozone concentration is controlled. A simple control method such as constant control is generally adopted, and the actual condition is that control based on the quality of treated water is not performed. Especially, the quality of treated water and waste ozone have been
The relationship with dissolved ozone has not been clarified.

Therefore, there is a possibility that ozone may be excessive or deficient due to fluctuations in inflow water quality and other factors, and it is difficult to obtain stable treated water quality by ozone treatment.

The present invention has been made in view of the above problems, and particularly sewage 2
It is an object of the present invention to provide an ozone generation amount control device capable of operating an ozone treatment tank at an optimum ozone injection rate to ensure a target water quality when ozone-treating secondary treated water. .

[0011]

In order to achieve the above object, the present invention diffuses the ozone gas obtained by the ozone generator into the raw water flowing into the closed type ozone treatment tank so that the oxidizing power of the ozone gas can be obtained. In the ozone treatment device which is configured to perform sterilization, deodorization and decolorization by utilizing the sterilizing power, the absorption efficiency controller is provided in the ozone treatment device, and the absorption efficiency of the ozone gas input to the absorption efficiency controller, in advance, Provided is an ozone generation amount control device which calculates an injection ozone concentration target value from a set absorption efficiency setting value and controls a driving state of an ozone generation device based on the injection ozone concentration target value. The absorption efficiency controller obtains the absorption efficiency of ozone gas by calculation from the ozone concentration injected into the ozone treatment tank and the exhaust ozone concentration from the ozone treatment tank.

[0012]

According to such an ozone generation amount control device, the raw water is allowed to flow into the ozone treatment tank and then the ozone generation device is started, so that the ozone gas generated from the ozone generation device is diffused into the treatment tank. And the desired sterilization, decolorization and deodorization are performed. During such operation, the absorption efficiency controller calculates the ozone gas absorption efficiency from the injected ozone concentration measurement value and the exhaust ozone concentration measurement value, and calculates the injection ozone concentration target value based on the calculated value and the absorption efficiency set value. The driving state of the ozone generator is controlled based on the injected ozone concentration target value, and the optimum injected ozone rate for the ozone treatment tank is obtained.

[0013]

EXAMPLES Specific examples of the ozone generation control apparatus according to the present invention will be described below. In the system schematic diagram of the present embodiment shown in FIG. 1, reference numeral 1 denotes a closed type ozone treatment tank into which raw water 2 such as sewage secondary treated water flows.

Reference numeral 3 is an ozone generator, and the ozone gas obtained by the ozone generator 3 is diffused through the diffuser pipe 4 into the raw water in the ozone treatment tank 1 and discharged from the upper wall of the ozone treatment tank 1. Ozone gas 5 is released. Reference numeral 11 is ozone-treated water.

In this embodiment, an absorption efficiency controller 6 is provided in such an ozone processing apparatus, and the ozone concentration injected into the ozone processing tank 1 measured by a measuring instrument 7 with respect to the absorption efficiency controller 6 and The exhaust ozone concentration of the exhaust ozone gas 5 measured by the measuring instrument 8 and the preset absorption efficiency set value 9 are input. Then, the absorption efficiency controller 6 calculates the absorption efficiency and the ozone concentration target value, and the calculated injected ozone concentration target value 1
0 is output to the ozone generator 3 to control the driving state of the ozone generator 3.

In practice, the ozone treatment tank 1 had an effective volume of 50 L and was kept at 20 ° C. in a water bath type constant temperature tank. Further, the gas phase ozone concentration was measured using an ultraviolet absorption type measuring device.

The operation mode of the ozone processing apparatus is as follows. That is, raw water 2 such as sewage secondary treated water that has been subjected to normal sand filtration or the like is caused to flow into the ozone treatment tank 1, and the ozone generator 3 is activated. Then, the ozone gas generated from the ozone generator 3 is diffused into the ozone treatment tank 1 through the air diffusing tube 4 and comes into contact with the inflowing raw water 2 as an upward flow to perform desired sterilization, decolorization and deodorization. I,
After that, it will be discharged as ozone-treated water 11 and used for scenic water.
Used for hydrophilic water.

During the above operation, the absorption efficiency controller 6
Calculates the ozone gas absorption efficiency from the injected ozone concentration measured value and the exhaust ozone concentration measured value, calculates the injected ozone concentration target value 10 from the calculated value and the absorption efficiency set value 9, and calculates the injected ozone concentration target value 10 Based on the above, the driving state of the ozone generator 3 is controlled to appropriately change the injection ozone rate to the ozone treatment tank 1.

The various measurement data and the analysis results which are the basis of this embodiment will be described below. First, FIG. 2 is a graph showing the relationship between the treated water chromaticity (degree) and the dissolved ozone concentration (mg / l) with respect to changes in the injected ozone concentration when the secondary sewage treated water after sand filtration is subjected to ozone treatment by the semi-batch method. From the figure, it can be seen that even if the dissolved ozone concentration is the same value, the chromaticity of the treated water is high when the injected ozone concentration is high. The sewage secondary treated water is urban sewage including dyeing wastewater, and the test water was sampled at the same time and at the same location.

FIG. 3 is a graph showing the relationship between the treated water chromaticity (degree) and the discharged ozone concentration (g / Nm ³ ) with respect to changes in the injected ozone concentration when ozone is treated by the same semi-batch method. As in the case of the ozone concentration, it can be seen that the chromaticity of the treated water is high when the injected ozone concentration is high even when the exhaust ozone concentration is the same value. Therefore, when the injected ozone concentration is changed, it is difficult to estimate the treated water quality from the dissolved ozone concentration and the exhaust ozone concentration.

Next, FIG. 4 is a graph showing the relationship between the treated water chromaticity and the absorption efficiency (%) with respect to the change in the injected ozone concentration when ozone is treated by the similar semi-batch method. It can be seen that the absorption efficiencies are almost the same regardless of the injected ozone concentration. Therefore, it is possible to estimate the treated water quality if the absorption efficiency is known.

Next, simulation results modeling ozone treatment will be shown. It is assumed that the ozone reaction tank is a continuous type and that it is in a completely gas-liquid mixed state. The reaction rate was a linear expression for chromaticity and ozone. The mass balance equation at this time is as follows.

Balance equation for ozone dO / dt = K _La (m · O _G −O) − (Q / V) · O−
y · k · S · O Balance formula for chromaticity dO / dt = (Q / V) · (S ₀ −S) −k · S · O where O: liquid ozone concentration, K _La : overall transfer capacity Coefficient m: Partition coefficient O _G : Ozone gas concentration Q: Treated water volume V: Reaction tank volume y: Yield k: Reaction rate constant S: Treated water chromaticity S ₀ : Influent water chromaticity Figure 5 shows simulated treated water chromaticity and dissolved ozone FIG. 6 is a graph showing the relationship with the concentration (mg / l), and FIG. 6 is a graph showing the relationship between the treated water chromaticity and the exhaust ozone concentration (g / Nm ³ ). Further, FIG. 7 is a graph showing the relationship between the treated water chromaticity and the absorption efficiency (%).

Therefore, even in the case of the ozone reaction tank, as in the case of the semi-batch system as shown in FIGS. 5 and 6, if the injected ozone concentration is different, the treated water has the same dissolved ozone concentration and exhaust ozone concentration. While the chromaticity is different, the absorption efficiency shown in FIG. 7 is approximately 1: 1 with the treated water chromaticity regardless of the injected ozone concentration.
It is understood that there is a relationship.

The above absorption efficiency can be calculated by the following equation. _{A bCAL = (O GIN -O GOUT} ) / O GIN × 100 ············ (1) _where, A bCAL: absorption efficiency O _GIN: injecting ozone concentration O _GOUT: discharge ozone concentration Next, the target value 10 of the injected ozone concentration is calculated from the calculated absorption efficiency A _bCAL and the absorption efficiency set value A _bSET in the following procedure. First, the absorption efficiency error signal E _b is calculated from A _bCAL and A _bSET by the following equation.

E _b = A _bSET −A _bCAL (2) Next, ( The ozone concentration target value O _GT is calculated using the following equation from E _b calculated by the equation 2) and the bias absorption efficiency A _bb .

O _GT = A _bb + K _P E _b + K _i ΣE _b・ ・ ・ ・ ・ ・ ・ ・ (3) where K _P : proportional Control gain K _i : Integral control gain From the above results, it is possible to monitor the change in the concentration of the substance highly reactive with ozone from the rise of the dissolved ozone and the reduction of the substance highly reactive with ozone. In particular, the water quality monitor based on the absorption efficiency in this embodiment is effective for the monitoring and control system according to the water quality in the ozone treatment equipment.

The absorption efficiency can be obtained from the concentration of injected ozone and the concentration of exhausted ozone, but in actuality, only the measurement of the vapor phase ozone concentration is required, and the operation is easy.

In the above description, the control example of the ozone generator in the sewage reuse is used, but the present embodiment is not limited to the above control, and all water treatments performed by using ozone gas are performed. It can also be applied to a device.

[0030]

As described in detail above, according to the present invention, when the ozone treatment tank is in operation, the absorption efficiency controller calculates the absorption efficiency of ozone gas from the injected ozone concentration and the exhaust ozone concentration to the ozone treatment tank, Calculate the injection ozone concentration target value from this calculated value and absorption efficiency setting value,
Since the drive state of the ozone generator is controlled on the basis of the injected ozone concentration target value, it is possible to perform control to optimize the injected ozone rate for the ozone treatment tank.

Particularly, in the present invention, the control based on the treated water quality is carried out so that the possibility of ozone excess or deficiency is eliminated even when a disturbance such as fluctuation of inflow water quality occurs, and the number of coliform bacteria, etc. It is possible to enhance the effect of removing odor and chromaticity and obtain stable treated water quality based on ozone treatment.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of an ozone generation amount control device according to the present embodiment.

FIG. 2 is a graph showing the relationship between the chromaticity of treated water and the concentration of dissolved ozone with respect to changes in the concentration of injected ozone when ozone is treated with a semi-batch method for secondary treated sewage.

FIG. 3 is a graph showing the relationship between the chromaticity of treated water and the concentration of discharged ozone with respect to changes in the concentration of injected ozone when ozone is treated by a semi-batch method with secondary treated sewage.

FIG. 4 is a graph showing the relationship between treated water chromaticity and absorption efficiency with respect to changes in injected ozone concentration when the secondary treated sewage is subjected to ozone treatment by the semi-batch method.

FIG. 5 is a graph showing the relationship between treated water color and dissolved ozone concentration by simulation in an ozone reaction tank.

FIG. 6 is a graph showing a relationship between treated water color degree and exhaust ozone concentration by a simulation in an ozone reaction tank.

FIG. 7 is a graph showing a relationship between treated water color and absorption efficiency by simulation in an ozone reaction tank.

[Explanation of symbols]

 1 ... Ozone treatment tank 3 ... Ozone generator 4 ... Air diffuser 5 ... Exhaust ozone gas 6 ... Absorption efficiency controller 7, 8 ... Measuring instrument 9 ... Absorption efficiency set value 10 ... Injection ozone concentration target value 11 ... Ozone-treated water

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C02F 1/50 531 R 540 A 550 BL L 1/78 ZAB (72) Inventor Koichi Shimizu Tokyo 2-1-17 Osaki, Shinagawa-ku Stock Company Meidensha

Claims (2)

[Claims] 1. A method for sterilizing, deodorizing and decolorizing ozone gas obtained by an ozone generator in the raw water flowing into a closed type ozone treatment tank, and utilizing the oxidizing and sterilizing power of ozone gas. In the above ozone treatment device, an absorption efficiency controller is provided in the ozone treatment device, and the injection ozone concentration target value is calculated from the absorption efficiency of the ozone gas input to the absorption efficiency controller and the preset absorption efficiency set value. Then, the ozone generation amount control device is characterized in that the drive state of the ozone generation device is controlled based on the injected ozone concentration target value. 2. The ozone generation amount control device according to claim 1, wherein the absorption efficiency controller obtains the absorption efficiency of ozone gas by calculation from the concentration of ozone injected into the ozone treatment tank and the concentration of ozone discharged from the ozone treatment tank. .