JPH04180888A - Ozone contact apparatus - Google Patents

Abstract

PURPOSE:To enhance the ozone absorbing efficiency of water to be treated by providing a packed bed under the water sprinkling device in a contact tank receiving ozone gas from the lower part thereof so as to position the same above the surface of the water. CONSTITUTION:A packed bed 11 is provided under a distributor 2 so as to be positioned above the surface of the water in a contact tank 1. The packed bed 11 is constituted of the packing material placed on a porous support plate 12. The water to be treated sprinkled from the distributor 2 flows down through the packed bed 11 to come into contact with the ozone gas rising through the packed bed 11 to absorb the ozone gas, and subsequently flows downward under the surface of the water to further come into contact with the ozone gas countercurrently to further absorb the ozone gas. The treated water having ozone absorbed therein enters a reaction tank 8 from a communication port 9 and flows upward to be discharged from an overflow port 10. Further, the water in the contact tank 1 is partitioned into many small sections by an accumulated body of grid bodies or honeycomb cylinders opened in up-and-down directions and, by arranging air diffusing spheres 3 to the lower parts of the centers of the respective small sections, water to be treated flowing downward is converted to plug streams and ozone absorbing efficiency can further be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to an ozone contacting device that improves the ozone absorption efficiency of treated water when the treated water is deodorized and sterilized with ozone.

<Prior Art> An ozone contacting apparatus is conventionally known in which ozone gas is vented into a contact tank from the lower part, and water to be treated is sprinkled from the upper part with a sprinkler to flow the water downward.

<Problem to be solved by the invention> In the bubble column type ozone contact device as described above, the mixing state of the water to be treated is close to complete mixing, so the ozone absorption efficiency is 80 to 9.
0%, which is low.

Conventionally, measures have been taken to increase the ozone absorption rate, such as dividing the ozone contact tank into multiple stages and recovering unreacted ozone (exhaust ozone gas) and bringing it into countercurrent contact with the liquid again.
Doing so would complicate the device and significantly increase installation costs.

In addition, a packed column type ozone contact device is also known from Japanese Patent Publication No. 54-24216, but its ozone absorption efficiency is lower than that of the bubble column type, and pump power is not used in the treatment process to purify river water. It is considered unsuitable for application because it involves water transfer due to a small height difference (head).

<Means for Solving the Problems> Therefore, the present invention was developed for the purpose of increasing the ozone absorption efficiency of the water to be treated without complicating the equipment and by utilizing the head water flow. A filling layer is provided below the water sprinkler and above the water surface.

Embodiments In each of the illustrated embodiments, reference numeral 1 denotes a contact tank, and the water to be treated is uniformly sprinkled from a distributor 2 provided at the upper part of the tank, and flows evenly downward in the tank. In addition, a header 4 with an aeration method 3 attached is provided at the bottom of the tank, and ozone gas is supplied to the header 4 through an air supply pipe 5 and uniformly flows upward in the tank from the aeration method 3. , is discharged from the discharge port 6 on the top wall. A reaction tank 7 of the same height is provided adjacent to the contact tank 1 and separated by a vertically divided wall 8, and a communication port 9 is provided at the bottom of the vertically divided wall 8 to communicate both tanks 1 and 7.
A water overflow port 10 is provided at the top of the reaction tank 7.

Therefore, the water that flows downward in the contact tank 1, comes into countercurrent contact with ozone gas and absorbs it, and becomes treated water enters the bottom of the reaction tank 7 from the communication port 9 and flows upward in the tank 7. Flow overflow outlet 1
Drained from 0. As a result, the water surface W of the water to be treated in the contact tank 1 becomes the overflow port 10 of the reaction tank.

A packed layer 11 is provided in the contact tank 1 above the water surface W and below the distributor 2. If a part of the packed bed 11 is provided submerged under the water surface, the diameter of the ozone gas bubbles increases due to association, and the gas surface area becomes smaller, so the effect of the filled bed in the submerged part is lost, and the absorption efficiency decreases accordingly. Although undesirable because of this, a packed bed above the water level can increase absorption efficiency. The filling layer 11 is composed of a filling material filled on a porous support plate 12.

Filling materials include crushed materials such as vinyl chloride, Teflon, stainless steel, polypropylene, magnetic materials, sand, and anthracite.
Any processed material may be used, but it is preferable that the quality is not changed by ozone. Further, the shape may be any shape such as spherical, cylindrical, cylindrical, irregular, etc., but the size is preferably about 10 to 200 mm, preferably about 20 to 100 mm, so that there is little resistance to the flow of water or gas. The bed height of the packed bed should be about 200 to 5000 mm, but it should be 300 mm due to the allowable water head difference and uniformity of water flow within the packed bed.
~1000mm is desirable.

The above-mentioned overflow port 10 of the reaction tank 7 is provided at a position lower than the lower surface of the packed bed so that the core layer is above the water surface W, depending on the height of the packed bed.

As a result, the water to be treated that is sprinkled from the distributor 2 comes into contact with and absorbs the rising ozone gas in the packed bed 11 when flowing down, and then, when flowing downward under the water surface. As mentioned above, it comes into countercurrent contact with ozone and further absorbs ozone. The treated water that has absorbed ozone in this way enters the reaction tank 8 through the communication port 9, flows upward in the tank, and is drained from the overflow port 10. This reaction vessel is for the reaction of residual dissolved ozone and provides sufficient residence time for the dissolved ozone to undergo an oxidation reaction and disappear.

If there is a head difference between the water to be treated and the treated water, the embodiment shown in Figure 1 will suffice, but if there is no head difference, a part of the water to be treated will be placed above the water surface of the contact tank as in the embodiment shown in Figure 2. The remainder of the water to be treated may be sprayed from above the packed bed 11 using the pump 13. In this case, the height of the packed bed should be 1000 to 5000 mm.
In addition, the amount of water to be treated that is sprayed from above onto the packed bed 11 by the pump 13 is 25 to 2 times the amount of the entire water to be treated.
About 5% is good.

In both the embodiments shown in FIGS. 1 and 2, the water in the contact tank 1 is partitioned into a large number of small sections using a vertically open lattice structure or an accumulation of honeycomb strips, and the aeration method 3 is applied to each section. By arranging it below the center of the small plot, the water to be treated flowing downward can be turned into a plug flow, further improving the ozone absorption efficiency.

- A square with sides of 2m and a height of 6m in a contact tank with a height of 6m.
The water to be treated is sprinkled from the position to maintain the depth of the water to be treated at 4 m, and a Raschig ring with a diameter of 25 mm is filled in the space between 4 m and 5 m from the bottom of the tank to form a packed bed. (Example) and an ozone contact device (Comparative Example) in which the depth of the water to be treated was kept at 5 m in the same contact tank and no packed bed was installed, and the results shown in the table below were obtained. Ta.

The water to be treated is river coagulation and sedimentation treated water, with an ozone gas concentration of 20 mg/12 and an ozone injection rate of 3 m
g / 12, boiling time of the water to be treated in the contact tank 10
minute, the water temperature was 30°C.

<Effects of the Invention> According to the present invention, since the absorption efficiency of ozone gas is increased, waste is reduced and costs can be reduced. Moreover, the amount of ozone discharged is reduced, and the processing cost is reduced.

Furthermore, since the absorption efficiency of ozone gas is stabilized against fluctuations in the quality of the water to be treated, the ozone concentration in the exhaust ozone gas is stabilized, and as a result, stable operation of exhaust ozone treatment becomes possible.

[Brief explanation of the drawing]

FIGS. 1 and 2 are cross-sectional views showing embodiments of the ozone contact device of the present invention. In the figure, 1 is a contact tank, 2 is a distributor that sprinkles the water to be treated, and 3
is the ozone gas diffusion method, 4 is the header, 5 is the air supply pipe, 6
is a discharge port for exhaust ozone gas, 7 is a reaction tank, 8 is a vertical side wall, 9
is a communication port, 10 is a treated water overflow port, 11 is a packed bed, 12
indicates a porous support plate. Applicant Kurita Kogyo Co., Ltd. Applicant
Munakata District Water Supply Enterprise Exit

Claims (1)

[Scope of Claims] An ozone contact device in which ozone gas is aerated into the contact tank from the lower part, and water to be treated is sprinkled from the upper part with a water sprinkler to pass the water in a downward flow. An ozone contact device characterized in that a packed layer is provided below and above the water surface.