JPH0329477B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an ozone treatment device that utilizes the strong oxidizing effect of ozone to sterilize, deodorize, and oxidize organic substances in water.

[Prior art and its problems]

Taking advantage of the fact that ozone has the strongest oxidizing power next to fluorine, water treatment is widely used to perform sterilization, deodorization, decolorization, and oxidation removal of organic and inorganic substances by diffusing ozone into water. ing.

The following ozone treatment apparatuses are known, for example, for causing a reaction between such ozone and water to be treated by ozone (hereinafter referred to as water to be treated). Specifically, there is an ejector method in which ozone is blown into the reaction tank using an ejector, and a bubble column method in which ozone is blown out as bubbles from the bottom of the reaction tank.In both cases, ozone is dissolved in the water to be treated.
Unreacted ozone is reacted with ozone-reactive substances such as organic substances in the water to be treated, and the unreacted ozone that is discharged without being dissolved in the water to be treated is rendered harmless through activated carbon spraying or thermal decomposition, and then released into the atmosphere. It is a device configured with

FIG. 3 shows an overview of the configuration of an apparatus for ozonating water to be treated in a batch manner using a bubble column method, as well as a conceptual diagram for explaining the operation. Third
In the figure, the ozone treatment device includes an ozone regeneration unit equipped with a blower pump 1, a dehumidifier 2, and an ozonizer 3, a water supply unit equipped with a liquid supply pump 4, and a check valve 5;
It consists of a reaction tank 6 having a diffuser plate 7, an ozone decomposition furnace 9, and a liquid discharge valve 10, which form a gas and liquid flow path through piping. Ozone treatment in this device is performed as follows. First, a certain amount of water to be treated is sent into the reaction tank 6 using the liquid sending pump 4. Next, ozone was aerated into the water to be treated in the reaction tank 6, and the ozone raw material was sent to the dehumidifier 2 by the blower pump 1 using air to remove moisture in the air that would cause a decrease in ozone generation efficiency. After that, the ozonized air is made into ozonized air through the ozonizer 3, and further this ozonized air is sent to the aeration pipe 7 provided at the lower part of the reaction tank 6, and the aeration is diffused into the water to be treated from the aeration pipe 7, thereby separating ozone and the water to be treated. When the water comes into contact, both react. At this time, ozone that is not dissolved in the water to be treated reaches the ozone decomposition furnace 9 from above the reaction tank 6, where it is decomposed into oxygen and then released into the atmosphere. Note that air is normally used as the raw material for ozone, but when it is desired to obtain ozone at a higher concentration, oxygen may be used instead of air. Also the third
In the figure, solid line arrows indicate the direction of liquid flow, and dotted line arrows indicate the air flow direction. After the ozone and the water to be treated are brought into gas-liquid contact for a predetermined period of time, the liquid discharge valve 10 can be opened to take out the treated water from the bottom of the reaction tank 6.

Next, we will discuss the problems in this water treatment process. The speed at which ozone reactants are removed from the water to be treated varies depending on the concentration of ozone dissolved in the water to be treated, and the higher the dissolved ozone concentration, the faster the removal speed of the ozone reactants. On the other hand, even if the pressure in the reaction tank 6 of the ozone treatment equipment is higher than atmospheric pressure by the pressure loss due to the pyrolysis furnace 9 for exhaust ozone treatment and the piping leading to it, this pressure loss is insignificant. It is almost equal to atmospheric pressure. The concentration of ozone dissolved in the water to be treated is
This is no different from when a normal gas dissolves in a liquid, and is proportional to the partial pressure of ozone.
Therefore, the concentration of dissolved ozone in the reaction tank 6 is proportional to the concentration of ozone fed from the ozone generator.

However, the concentration of ozone that can be generated with a normal ozonizer is approximately 30% even when oxygen is used as the raw material.
It is very dilute at mg/mg. In actual water treatment, using oxygen as a raw material poses problems in terms of transportation, storage, etc., so air is often used as a raw material for ozone generation. Generally, the ozone concentration of the gas obtained from an ozonizer is approximately proportional to the square root of the oxygen concentration of the raw material, so when air is used as the raw material, the ozone concentration is only about half that of when oxygen is used as the raw material. When the ozone concentration of the ozonized air generated from the ozonizer 3 is low, the ozone concentration dissolved in the water to be treated in the reaction tank 6 is also low.
Therefore, the speed of removing ozone-reactive substances from the water to be treated is slow, and there are problems with long treatment times and low efficiency, and as a result, it cannot be said that the powerful oxidizing ability of ozone is fully utilized. .

[Purpose of the invention]

The present invention has been made in view of the above-mentioned points, and its purpose is to eliminate ozone-reactive substances in the water to be treated even if the concentration of ozone in the ozonized air or oxygen diffused into the water to be treated is low. An object of the present invention is to provide an ozone treatment device that can remove ozone efficiently in a short time.

[Key points of the invention]

The present invention makes it possible to maintain the pressure inside the reaction tank above atmospheric pressure by providing a pressure regulating means in the piping that communicates with the reaction tank and the exhaust ozone treatment section of the ozone treatment equipment described above. This is designed to increase the ozone concentration.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a conceptual diagram showing the construction and treatment system of a water treatment apparatus according to the present invention, and parts common to those in FIG. 3 are given the same reference numerals. 1 differs from FIG. 3 in that a pressure regulating valve 8 is provided outside the reaction tank 6 in the middle of the piping from the reaction tank 6 to the ozone decomposition furnace 9. Since the operation of this apparatus for ozone treatment is basically the same as that shown in FIG. 3, the explanation will be omitted and only the main points will be described. In Figure 1, reaction tank 6
Ozone that is not dissolved in the water to be treated passes through the pressure regulating valve 8 and reaches the ozone decomposition furnace 9, where it is decomposed into oxygen. The pressure regulating valve 8 serves to maintain the pressure inside the reaction tank 6 at a set pressure higher than atmospheric pressure and to increase the dissolved ozone concentration in the water to be treated, and is preferably a spring-type safety valve, for example.

Further, in the present invention, instead of the pressure regulating valve 8, other pressure regulating means are used, for example, a part of the piping communicating with the reaction tank 6 and the ozone decomposition furnace 9 is made into a pipe with a small flow passage cross-sectional area to increase the pressure loss. Possibly reaction tank 6
Methods such as increasing the internal pressure may also be used. Accordingly, in the present invention, the pressure within the reaction tank 6 can be maintained at a level higher than atmospheric pressure using such a pressure regulating means, so that dissolved ozone in the water to be treated becomes highly concentrated and gas-liquid contact is performed. From the above, when ozone treatment is performed using the apparatus of the present invention, the ozone treatment time is shortened.

Next, by increasing the pressure inside the reaction tank 6,
Experimental results using the apparatus of the present invention will be explained as to how the treatment time for ozone reactants in water to be treated is shortened.

As the water to be treated, a standard solution containing 30 mg/ammonium ion (NH ₄ ⁺ ) as nitrogen and adjusted to a pH of approximately 12 was used. NH ₄ ⁺ is oxidized to nitrate ions (NO ₃ ^- ) by ozone oxidation, but this reaction progresses faster as the pH is higher, so the pH was adjusted to about 12 and the water to be treated was used. Pour 300ml of this water to be treated into the reaction tank 6, change the pressure inside the reaction tank 6 by adjusting the pressure regulating valve 8, and start aeration of ozone into the water to be treated, every 10 minutes. The treated water was sampled to measure the reduction in NH ₄ ⁺ . In this experiment, oxygen was used as the raw material for ozone, and the voltage of the ozonizer 3 was kept constant. Ozone concentration is 23
mg/(atmospheric pressure standard), and the ventilation rate is 0.4 (atmospheric pressure standard)/min. The experimental results are shown in Figure 2.

Figure 2 shows the pressure inside the reaction tank in gauge pressure.
This is a diagram showing the relationship between the ozone ventilation time and the residual rate of NH ₄ ⁺ when the pressure is 0.65Kg/cm ² and 1.90Kg/cm ² .For comparison, the pressure in the reaction tank is atmospheric pressure. Also listed. In Figure 2, curve A is 0.65Kg/
cm ² , curve B represents 1.90Kg/cm ² , and curve C represents atmospheric pressure. As can be seen by comparing the three curves in Figure 2, in the case of curves A and B, in which the inside of the reaction tank was kept under pressure, the residual rate of NH ₄ ⁺ decreased quickly.
In curve C under atmospheric pressure condition, even if ozone is aerated for 60 minutes, 42% of NH ₄ ⁺ still remains in ^the water to be treated. As shown, NH ₄ ⁺ is almost completely oxidized to NO ₃ ^- . Furthermore, when the pressure is maintained at 1.90 Kg/cm ² , the oxidation rate of NH ₄ ⁺ becomes even higher as shown in curve B.

From the above, keeping the inside of the reaction tank in a pressurized state,
By increasing the dissolved ozone concentration in the water to be treated,
Ozone's inherently strong oxidizing power can be fully utilized, and extremely high treatment efficiency can be achieved in a short period of time.

In addition, the present invention can obtain the same effect by using an activated carbon adsorption tower instead of a pyrolysis furnace in the exhaust ozone treatment section by equipping it with a pressure adjustment means, and also by using a level system for taking out the treated water instead of a batch system. It is possible to produce the same effect as a continuous type device composed of a meter, a flow rate regulating valve, etc. by providing pressure regulating means.

In addition, the pressure regulating means for increasing the dissolved ozone concentration according to the present invention need only be installed in the piping between the reaction tank and the exhaust ozone treatment section, which has a sealed structure against harmful ozone, so there is no need to take any special considerations. Other advantages include that the ozonizer can be easily installed and that the scale of the ozonizer can be reduced if the ozonizer can be treated at the level of ozone treatment at atmospheric pressure using the device of the present invention. There is also.

〔Effect of the invention〕

In conventional water treatment equipment that uses ozone, the ozone concentration of the gas generated from the ozonizer is low, so when aeration is diffused into the water to be treated in the reaction tank at atmospheric pressure, the concentration of dissolved ozone in the water to be treated is also low. So,
The rate of oxidation removal of ozone reactants is reduced,
In contrast to the problem of poor treatment efficiency, in the present invention, as explained in the embodiment, by providing a pressure adjustment means in the piping between the reaction tank and the exhaust ozone treatment section, the pressure inside the reaction tank can be raised to above atmospheric pressure. Since the concentration of dissolved ozone in the water to be treated is increased by maintaining the ozone in the water, the strong oxidizing power that ozone originally has can be fully utilized, and extremely high ozone treatment efficiency can be obtained in a short period of time.

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram showing the equipment configuration and treatment system of the present invention, Fig. 2 is a diagram showing the relationship between ozone ventilation time and NH ₄ ⁺ residual rate in ozone treatment using this equipment, and Fig. 3 is a conventional FIG. 2 is a conceptual diagram showing the configuration and processing system of the device. 1...Blower pump, 2...Dehumidifier, 3...Ozonizer, 4...Liquid pump, 5...Check valve, 6
...Reaction tank, 7...Scatter plate, 8...Pressure adjustment valve,
9...Ozone decomposition furnace, 10...Liquid discharge valve.

Claims (1)

[Claims] 1. A reaction tank having a diffuser plate and containing a certain amount of water to be treated, an ozone generation section having an ozonizer that generates ozone to be injected into the reaction tank, and injection of water to be treated to be sent to the reaction tank. a part, an exhaust ozone treatment part that renders unreacted ozone in the reaction tank harmless and releases it to the outside; and a pressure adjustment means provided in a part of the piping that communicates with the reaction tank and the exhaust ozone treatment part. ozone treatment equipment. 2. In the device according to claim 1,
An ozone treatment device characterized in that the pressure adjustment means uses a spring type safety valve. 3. In the device according to claim 1,
An ozone treatment apparatus characterized in that the pressure adjustment means uses a pipe having a flow passage cross-sectional area smaller than that of the pipe.