JPS59109288A - Waste water treating device - Google Patents

Abstract

PURPOSE:To feed effectively ozone into waste water by providing the 1st diffuser which feeds ozone in the form of foam into the waste water in the lower part in a tank and the 2nd diffuser which is made larger in the size of the holes for generating foam in the upper part in the tank. CONSTITUTION:Waste water is introduced through an introducing pipe 2 into a reaction vessel, and the waste water after the treatment is discharged through a release pipe 8. The ozone from an ozonizer 10 is introduced through an introducing pipe 4 for ozone and a valve 15 into the 1st diffuser 5 which is provided in the lower part of the vessel 1 and is formed of a porous material. The ozone is thus fed into the waste water. The valve 15 is closed and a valve 7 is opened to supply the ozone to the 2nd diffuser 16 in the initial period of the treatment. The diameter of the holes provided to the diffuser 16 is made larger as compared to the diffuser 5 and the ozone supplied from the diffuser 16 reacts less in the lower part of the reaction vessel but rises up to near the water surface and acts effectively on the foam near the water surface. The defoaming is thus accomplished with good efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an ozone reaction type wastewater treatment device that treats pollutants in wastewater by injecting ozone into the wastewater.

[Technical background of the invention and its problems]

Ozone, which has strong oxidizing power, has recently begun to be used in various wastewater treatments to prevent pollution. The use of ozone in wastewater treatment is suitable for the oxidative decomposition of pollutants that are difficult to treat with conventional biological treatment, or pollutants that are toxic to living organisms, such as cyanide compounds and phenolic compounds. There is.

In recent years, due to the increase in water demand, an increasing number of companies are not only treating and discharging wastewater, but also reusing wastewater by performing advanced treatment that combines physical, biological, and chemical treatments. Furthermore, with the development of urban sewage systems, the amount of secondary treated sewage discharged from treatment plants has increased9, and conventional sedimentation and biological treatment alone are insufficient to purify the water, resulting in increased pollution of rivers and the sea after discharge. ing. Therefore, from the standpoint of environmental conservation, more advanced sewage treatment is required.

Due to this increase in demand for water, research and development efforts are being carried out in various places to provide advanced treatment to this large amount of secondary treated sewage water and to purify it to the point where it can be used as industrial water. For advanced treatment of these factory wastewater or secondary sewage treatment,
The oxidizing power of ozone is utilized. Ozone is effective in deodorizing, decolorizing, sterilizing, and decomposing other organic contaminants, and is particularly effective in inactivating viruses. After ozone is added, excess ozone self-decomposes into oxygen, so there are no problems such as residual treatment chemicals or increased salt concentration, unlike in conventional chlorine treatment.

Furthermore, ozone has the advantage that it can be easily generated using electricity alone using air or oxygen as a raw material.However, ozone is a gas at room temperature, and the ozone concentration obtained from an ozone generator is 1% when air is used as a raw material. (by weight), and when oxygen is used as a raw material, a concentration of only about 2 inches can be obtained. For this reason, a gas-liquid contacting device is required to treat wastewater using ozone, and generally a porous dihyuser, a suction type injector, etc. are used to increase the gas-liquid contact area and introduce ozone into the wastewater. Injecting air or oxygen. Industrial wastewater to be treated includes water-soluble cutting oil,
Wastewater 10 containing a large amount of surfactants, such as fluorescent flaw detection liquid, and wastewater from the dyeing industry contain not only dyes but also many water-soluble polymer substances and surfactant agents as adhesives and detergents. In addition, when it comes to industrial wastewater that is intended for reuse, detergent often flows into cafeteria wastewater. On the other hand, sewage treatment 3”fl, 1%
In the secondary treated sewage water, substances that are difficult to treat using the activated sludge method, such as detergents from domestic wastewater and protein components from human waste, remain in the secondary treated sewage water.

Wastewater containing these substances has a strong foaming property and becomes a hindrance to various wastewater treatment operations. Ozone's strong oxidizing power can oxidize and decompose these foaming components, converting them into low-molecular molecules and defoaming them.

Conventionally, wastewater treatment equipment using ozone has a short time of gas-liquid contact,
Ozone-containing gas is injected as fine bubbles from the bottom of the reaction tank in order to increase the water pressure and bubble contact area and promote the melting and reactivity of ozone.

Furthermore, unreacted ozone discharged from the upper part of the reaction tank is completely decomposed using activated carbon or a catalyst in the ozone decomposition tank to prevent air pollution.

However, when treating wastewater containing a large amount of foaming components, steady operation becomes difficult as described below. However, at the initial stage of operation, the foaming component in the reaction tank is present at a uniform concentration. When ozone-containing gas is injected, most of the ozone is consumed in the lower part of the reactor, and the ozone concentration in the rising bubbles becomes very low. Therefore, in the upper part of the reaction tank, the phenomenon is the same as that of bubbling simply due to gas injection. This also applies if there are substances in the wastewater that are more likely to react with ozone than foaming components. Bubbles generated above the upper part of the reaction tank VC, a certain space body λ, wets the activated carbon or catalyst layer in the ozone decomposition tank provided for decomposing the exhaust ozone coming out from the upper part of the ozone reaction tank, increasing the pressure resistance, and further Reduces the effective surface area required for exhaust ozone decomposition.

For this reason, even during regular operation after the foaming component has been oxidized with ozone, complete exhaust ozone decomposition is difficult. This problem caused by foaming can occur even in continuous treatment due to fluctuations in water quality.

Conventionally, pouring water into the generated foam to eliminate the foam has been carried out in general wastewater treatment. However, this method only destroys the foam, but does not essentially decompose and remove the foaming components. A method of defoaming foam by spraying an ozone-containing substance onto the foam is also known, but in this case, most of the ozone is released from the upper part of the ozone reaction tank as waste ozone, so it is not economical.

[Purpose of the invention]

The purpose of the present invention is to suppress foaming by effectively injecting ozone into the foam that is generated in the initial stage of the operation when wastewater containing a large amount of foaming components is ozonated. To provide an improved wastewater treatment device that completely prevents the transition to wastewater and allows stable treatment operations to be continued.
is.

[Summary of the invention]

The wastewater treatment device according to the present invention includes a tank in which wastewater is stored;
A first dihydrator provided at the lower part of the tank and which sends ozone into the wastewater as bubbles, and a pore diameter larger than that of the first dihyuser which is provided in the tank and which generates ozone bubbles in the wastewater. The ozone bubbles generated from the second dihyzer are used to suppress foaming.

EXAMPLE Hereinafter, the present invention will be described in detail with reference to an example shown in the drawings. In FIG. 1, reference numeral 1 denotes an ozone reaction tank for injecting ozone into wastewater to treat pollutants in the wastewater. The wastewater to be treated is introduced into the ozone reaction tank 1 through the inlet pipe 2, and the treated wastewater is discharged through the discharge pipe 8. Ozone generated in the ozone generator IO is introduced through the ozone introduction pipe 4 and the valve 15 to the first dihyuser 5 made of a porous material provided in the F section of the ozone reaction tank l, and from this first dihyuser 5. Injected into wastewater.

Ozone that remains unreacted in the ozone reaction tank 1 is sent to the ozone decomposition tank 11 through the exhaust ozone pipe 3, where the ozone is decomposed into harmless oxygen gas and released into the atmosphere. As mentioned above, the ozone decomposition tank 11 is composed of activated carbon, catalyst, etc., but when water adheres to its surface, the active area decreases. As a result, the ozone decomposition ability decreases, and in some cases, ozone may be released into the atmosphere without being decomposed, causing pollution.

Reference numeral 16 indicates a second part provided especially for defoaming in the present invention.
Ozone is supplied from the ozone introducing pipe 4 through a branch pipe 9 and a valve 7 at the dihydrogen user. The second dihydr user 16 is provided near the first dihy user 5 in the ozone reaction tank 1, and has a larger pore size for generating bubbles than the first dihy user 5.

In the above configuration, at the beginning of wastewater treatment, first, the valve 15 is closed and the valve 7 is opened to supply the second dihyuser 16Vc ozone. Since the pore diameter of the second dihyuser 16 is larger than that of the first dihyuser 5, the diameter of the ozone bubbles generated is large and the solubility of ozone is reduced. The ozone supplied from this spoiler user 16 undergoes little reaction in the lower part of the reaction tank 1, and the ozone concentration rises to near the water surface without decreasing, so it effectively acts on bubbles near the water surface and extinguishes them efficiently. I can do it. When defoaming progresses, the valve 7 is closed and the valve 15 is opened to supply ozone to the first dihyuser 5. Since the pore diameter of the first dehydrator 5 is small, the diameter of the ozone bubbles is also small and the solubility is high, so that the ozone bubbles are effectively dissolved in the ozone reaction tank and ozone treatment is performed efficiently.

FIG. 2 is a diagram showing the occurrence of bubbles when the second dihyuser 16 is used (A) and when FB+ is not used.

In other words, in case (B), the bubble height h is the ozone reaction phase l.
The bubbles move to the ozone decomposition tank 11 when the height of the space above the water surface becomes higher than hO, and the case of (A) shows that this can be prevented.

〔Effect of the invention〕

As explained above, according to the present invention, in an ozone reaction type wastewater treatment apparatus that injects ozone into wastewater to treat pollutants in the wastewater, in addition to the first dihyuser that injects reactive ozone, By installing a second dehydrator with a large pore size for bubble generation, which is used to break down the bubbles near the water surface that are often present in the early stages of operation, bubbles are effectively extinguished. This can prevent the ozone decomposition ability from decreasing. Therefore, it is possible to obtain a rational wastewater treatment device that can continue to operate safely without emitting residual ozone into the atmosphere.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing an embodiment of the wastewater treatment apparatus according to the present invention, and FIG. 2 is a characteristic diagram showing the defoaming effect according to the present invention. l...Ozone reaction tank, 5...Main first dihyuser, 16...Second dihyuser, 1o...Ozone generator, 11...Ozone decomposition tank.

Claims (1)

[Claims] a tank in which wastewater is stored; a first dihyuser provided in the F part of the tank and feeding ozone into the wastewater as bubbles;
and a second dihyuser provided in the tank and having a pore diameter larger than that of the M1 dihyuser for generating air bubbles in the wastewater.