JP2000263071A - Apparatus and method for treating water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment method whereby the decomposition of substances to be decomposed such as dioxins and hardly biodegradable organic substances is accelerated to clean water by connecting an ozone supply pipe to a pipe for supplying water to be treated at the suction side of a pressurized supply pump and connecting a pressurized ultraviolet ion apparatus to a pipe for supplying water to be treated containing ozone dissolved therein at the delivery side. SOLUTION: When the pH, measured with a pH-adjusting meter 12, of raw water introduced into a raw water vessel 1 is different from a specified value, the pH is adjusted by the adjusting meter 12 to a specified value by supplying an alkali liquid from an alkali storage vessel 9 or an acid from an acid storage vessel 10. The raw water having the pH adjusted is extracted with a pressurized supply pump 2, and an ozonized gas generated by an ozone generator 4 is supplied to give ozone-containing raw water, which is then pressurized and supplied to a pressurized ultraviolet radiation apparatus 3, While the raw water is flowing upwardly through a tightly closed column 5, substances to be decomposed such as dioxins, hardly biodegradable substances, and COD source substances in the raw water are efficiently decomposed by the actions of ozone under pressure and ultraviolet rays from an ultraviolet lamp 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for purifying treated water such as sewage and night soil, rivers and lakes, leachate at a final waste disposal site, and various industrial effluents. More specifically, the present invention relates to a water treatment apparatus and a water treatment method for purifying water to a high degree using ozone and ultraviolet rays in combination.

[0002]

2. Description of the Related Art Conventionally, a method of purifying water by decomposing COD in water, a biodegradable organic substance and a harmful organic substance by utilizing the strong oxidizing action of ozone, and utilizing a photochemical action of ultraviolet rays. A method of disinfecting microorganisms such as pathogenic bacteria in water has been implemented, and a method of purifying water by using ozone and ultraviolet rays in combination and utilizing a synergistic effect thereof has also been implemented.

In the above-mentioned method of purifying water using both ozone and ultraviolet light, ozone is decomposed by ultraviolet light,
Hydroxy radicals having a stronger oxidizing power than ozone are generated, and organic substances are oxidized and decomposed by the hydroxy radicals. Japanese Unexamined Patent Publication (Kokai) No. 6-277660 discloses that an ultraviolet irradiation device is provided at the latter stage of an ozone reaction device. Ozone (a gas containing ozone; hereinafter, referred to as ozonized gas) is supplied to the reactor to oxidize and decompose organic substances in the water to be treated with ozone. Discloses an apparatus for further performing an oxidative decomposition treatment.
No. 8377 discloses a method of irradiating ultraviolet rays while supplying an ozonized gas into the water to be treated in an ozone treatment tank provided with an ultraviolet lamp to oxidatively decompose organic substances in the water to be treated. .

[0004] Further, Japanese Patent Application Laid-Open No. 7-108285 discloses that ultraviolet rays while supplying ozonized gas are used for the treatment of dioxins contained in sewage such as leachate at a final waste disposal site and various industrial wastewaters. Japanese Patent Application Laid-Open No. 10-76295 discloses a method for decomposing and removing dioxins and dissolved dioxins contained in sewage such as leachate and various industrial effluents at a final waste disposal site. A method of decomposing and removing organic pollutants by irradiating with ultraviolet rays while supplying an ozonized gas is disclosed.

[0005]

In the conventional methods for purifying water using both ozone and ultraviolet light, the ozonized gas is diffused and supplied under normal pressure, but most of the ozonized gas is supplied. Oxygen and nitrogen, ozone concentration is 10
Since the solubility of ozone in water at normal temperature and pressure is extremely low, 5 to 6 mg / L, ozone is not sufficiently dissolved in the water to be treated, and most of the ozonized gas is air bubbles. As a result, the contact efficiency between ozone and an object to be treated such as dioxin or a soluble organic pollutant is low, and decomposition of the object to be treated becomes insufficient. Therefore, there is a problem that the processing efficiency with respect to the supply amount of ozone is low.

[0006] Further, when the ozonized gas flows as bubbles, the ultraviolet rays are absorbed by the bubbles, and the ultraviolet rays cannot be applied to the entire water to be treated in the treatment apparatus. Therefore, there is a problem in that hydroxy radicals having strong oxidizing power are not sufficiently generated from ozone, and a sufficient effect cannot be obtained by the combined use of ozone and ultraviolet rays, and the processing efficiency is low.

The present invention has been made in view of the above-mentioned problems of the prior art, and by sufficiently dissolving ozone and irradiating it with ultraviolet rays, the generation of hydroxyl radicals from ozone is sufficiently carried out. The object of the present invention is to provide a water treatment apparatus and a water treatment method capable of purifying water by accelerating the decomposition of an object to be treated such as dioxins and organic substances that are hardly biodegradable by an oxidizing power. .

[0008]

According to the first aspect of the present invention, there is provided an ozone generator for generating an ozonized gas, and a pressurized supply of water to be treated. A pump and a pressurized ultraviolet irradiation device in which an ultraviolet lamp is installed are provided, and an ozone supply pipe for supplying an ozonized gas generated by an ozone generator to a water supply pipe to be treated on the suction side of the pressurized supply pump is provided. The water treatment apparatus is characterized in that a pressurized ultraviolet irradiation device is connected to a treated water supply pipe in which ozone is dissolved on the discharge side of the pressurized supply pump.

According to the second aspect of the present invention, the ozonized gas generated by the ozone generator is supplied from the ozone supply pipe to the to-be-treated water supply pipe on the suction side of the pressurized supply pump. And the ozonized gas are mixed, and the ozonized gas is mixed and the ozone-dissolved water to be treated is supplied to the pressurized ultraviolet irradiation device from the treated water supply pipe on the discharge side of the pressurized supply pump, and the pressurized ultraviolet irradiation is performed. A water treatment method characterized by irradiating ultraviolet rays under pressure in an apparatus to treat water to be treated with ozone and ultraviolet rays.

In the above construction, the ozonized gas generated by the ozone generator is supplied to the treated water supply pipe on the suction side of the pressurized supply pump. Gas can be mixed well,
Since the solubility of ozone is increased by the pressurized state, ozone can be completely dissolved. Further, in the pressurized ultraviolet irradiation apparatus, the water to be treated in which ozone is dissolved is irradiated with ultraviolet rays while maintaining the pressurized state, so that no bubbles are generated, and therefore, the ultraviolet irradiation efficiency can be increased, and hydroxyl radicals from ozone can be increased. Can be sufficiently generated, and decomposition of the object to be treated such as COD, biodegradable organic matter, and dioxins in the water to be treated can be promoted.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system diagram of one embodiment of the present invention. Reference numeral 1 denotes a raw water tank for storing treated water (hereinafter referred to as raw water) such as treated water such as sewage and human waste, river water, lake water, leachate from a final waste disposal site or various industrial wastewaters, and includes a stirrer 11 and raw water. Measure pH and pH
A raw water inlet pipe A for introducing raw water, a raw water supply pipe B for drawing and drawing the raw water by the pressurized supply pump 2, and a sodium hydroxide for adjusting the pH of the raw water. Alkaline solution such as alkaline storage tank 9
An acid supply pipe I for supplying an acid such as sulfuric acid from the acid storage tank 10 and a treated water circulation pipe E for circulating treated water are connected and arranged.

Reference numeral 2 denotes a pressurized ultraviolet irradiation device 3 from the raw water tank 1.
And an ozone supply pipe G for supplying the ozonized gas generated by the ozone generator 4 to the raw water supply pipe B on the suction side of the pressurized supply pump 2. Connected. A raw water supply pipe C for supplying raw water in which ozone is dissolved to the pressurized ultraviolet irradiation device 3 is connected to the discharge side of the pressurized supply pump 2. As the pressurized supply pump 2, any pump that can supply high pressure, such as a cascade pump or a Wesco pump, can be used.

Reference numeral 3 denotes an internally illuminated, pressurized type ultraviolet irradiation device in which an ultraviolet lamp 6 vertically extending in the axial direction inside a vertically standing cylindrical closed column 5 is provided. A raw water supply pipe C in which ozone is dissolved is connected to the side surface, and a reaction water discharge pipe D is connected to the upper end side surface.
Further, the shape of the closed column 5 may be a rectangular tube or a tank other than the cylinder.

The ultraviolet lamp 6 is controlled by an ultraviolet irradiation operation panel 7, and the wavelength of the irradiated ultraviolet light is 185.
nm and 254 nm or 300 nm are used,
It is preferable to use ultraviolet rays of 185 nm and 254 nm. Further, since the inside of the closed column 5 is in a pressurized state, it is preferable that the ultraviolet lamp 6 is surrounded by a protective tube formed of an ultraviolet transmitting material such as a quartz tube.
Is set as appropriate according to the processing amount, the difficulty of the processing, the lamp performance, and the like.

Reference numeral 4 denotes an ozone generator for generating an ozonized gas. As the ozonized gas, air, pure oxygen, or the like is used, and these gases are electrically irradiated by ultraviolet irradiation or discharge under pressure or normal pressure. This device converts a part of oxygen to ozone by performing a chemical reaction.

Reference numeral 8 denotes a gas-liquid separator connected to the lower part of the reaction water discharge pipe D of the pressurized ultraviolet irradiation device 3 for separating waste gas containing unreacted ozone from the reaction water discharged from the discharge pipe D. And a waste gas exhaust pipe J is connected to the top,
Further, an ozone treatment device such as an activated carbon tower or a catalytic reaction tower (not shown) is provided downstream of the waste gas discharge pipe J.

Hereinafter, the water treatment method according to one embodiment of the present invention will be described in more detail. Raw water is introduced into the raw water tank 1 from the raw water introduction pipe A, and the pH of the raw water is measured by the pH controller 12, and if the pH of the raw water is not a predetermined value, the raw water is controlled by the pH controller 12 to control the alkali. The alkali liquid is supplied from the storage tank 9 through the alkali supply pipe H, or the acid is supplied from the acid storage tank 10 through the acid supply pipe I to adjust the pH to a predetermined value. The pH is adjusted while moving the stirrer 11 and mixing uniformly. Also, as the value of pH,
Adjustment to 6.5 to 7.5 is preferable because the reaction efficiency of ozone and the like is high.

Raw water adjusted to a predetermined pH is extracted from the raw water supply pipe B by the pressurized supply pump 2 and generated by the ozone generator 4 from the ozone supply pipe G connected to the suction side of the pressurized supply pump 2. The supplied ozonized gas is supplied, and the raw water and the ozonized gas are mixed to obtain ozone-dissolved raw water in which the ozonized gas is mixed. It is supplied to the ultraviolet irradiation device 3.

The ozone concentration in the ozonized gas generated by the ozone generator is 10 to 200 gO3 / Nm3, and the mixing amount of the ozonized gas in the raw water supplied by the pressurized supply pump 2 is as follows: It is 3 to 15 vol%. 3vo
When the amount is less than 1%, the decomposition efficiency of the object to be treated is insufficient and the treatment efficiency is lowered. When the amount is more than 15% by volume, the ozonized gas is incompletely dissolved, so that bubbles remain, which impedes the transmission of ultraviolet rays. Absent. The ozone concentration in the ozone-dissolved raw water mixed with the ozonized gas is 20 to 100.
mg / L, preferably 50-100 mg / L.

Further, the pressure of the raw water pressurized by the pressurized supply pump 2 is 0.5 to 5 kg / cm 2, preferably 1 to 5 kg / cm 2.
The pressure is 3 kg / cm 2, and the ozone gas is completely dissolved in the raw water by this pressure. If the pressure is 0.5 kg / cm 2 or less, the dissolution is incomplete and bubbles remain. If the pressure is 3 kg / cm 2 or more, the entire device needs to be manufactured from a material having high pressure resistance, which causes a problem that the device cost increases.

In the above, the amount of raw water sucked by the pressurized supply pump 2 is controlled by a flow meter 13, and the supply amount of ozonized gas mixed with the raw water is controlled by a flow meter 14. Further, the pressure in the raw water supply pipe is a pressure gauge 15 on the suction side of the pressurized supply pump 2 and a pressure gauge 1 on the discharge side.
6 is monitored and controlled.

Pressurized ultraviolet irradiation device 3 from raw water supply pipe C
The ozone-dissolved raw water supplied to the column is circulated in the upward direction through the closed column 5, and is irradiated with ultraviolet rays from an ultraviolet ray lamp 6 provided therein. Dioxins and biodegradable substances in water and C
Decomposed substances such as OD-reducing substances are efficiently decomposed. The decomposition described above is caused by the fact that ozone dissolved in raw water generates ultraviolet light with a stronger oxidizing power than ozone by ultraviolet rays, and organic substances are oxidized and decomposed by the hydroxyl radical.

The ultraviolet light to be irradiated has a wavelength of 1
85 nm and 254 nm or 300 nm are used, but it is preferable to use ultraviolet rays of 185 nm and 254 nm. The residence time of the raw water supplied to the pressurized ultraviolet irradiation device 3 is 5 to 60 min, preferably 10 to 30 m.
When the residence time is less than 5 minutes, the decomposition of the decomposed substance is insufficient, and when the residence time is 60 minutes or more, the pressure type ultraviolet irradiation device 3 becomes excessively large.

The treated water treated with ozone and ultraviolet rays is discharged from the treated treated water discharge pipe D and supplied to the gas-liquid separator 8 to separate waste gas containing unreacted ozone from the treated treated water. The waste gas is supplied from a waste gas discharge pipe J to an ozone treatment apparatus such as an activated carbon tower or a catalytic reaction tower (not shown) to treat unreacted ozone and discharge it to the atmosphere. Further, the treated water from which the waste gas has been separated is circulated from the treated water circulation pipe E to the raw water tank 1. In the case of a continuous treatment, a part of the treated water is discharged from the treated water discharge pipe F to the outside of the system. It is performed by

Next, an embodiment in which water is treated by the above-described apparatus and method will be described. (Example 1) Using leachate of waste as raw water, an ozonized gas having an ozone concentration of 30 gO3 / Nm3 was converted to 7 vol% of raw water.
Mixed. The raw water was pressurized to 3 kg / cm 2 by a pressurized supply pump and supplied to the pressurized ultraviolet irradiation device 3, irradiated with 185 nm and 254 nm ultraviolet rays, and treated for a residence time of 30 min. As a result, the COD of 10 mg / L of the raw water could be reduced to 1.2 mg / L of COD with the treated water.

(Example 2) Dioxins were converted to 77.1 p
Using raw water containing g / L (1.05 pg-TEQ / L), 7% by volume of raw water was mixed with ozonized gas having an ozone concentration of 30 gO3 / Nm3. 2. Raw water is supplied by a pressurized supply pump.
It was pressurized to 0 kg / cm 2, supplied to the pressurized ultraviolet irradiation device 3, irradiated with 185 nm and 254 nm ultraviolet rays, and treated for a residence time of 30 min. As a result, raw water dioxins were converted to 3.4 pg / L (0.01 pg-TEQ /
L).

Example 3 Hexachlorobenzene was added to 58
Using raw water containing μg / L, ozone concentration 40 mg O3
/ Nm3 of the ozonized gas was mixed with 5 vol% of raw water.
Raw water is pressurized to 3.0 kg / cm 2 by a pressurized supply pump and supplied to the pressurized UV irradiation device 3 to be 185 nm and 254 nm.
Irradiated with ultraviolet rays of nm, the treatment was performed for a residence time of 30 min. As a result, 18 μg of hexachlorobenzene in raw water
/ L.

[0028]

According to the present invention, ozone gas can be reliably dissolved by supplying an ozonized gas into the water to be treated in a pressurized state, and ultraviolet rays are irradiated in a bubble-free state. The present invention provides a water treatment apparatus and a water treatment method in which generation is sufficiently performed, and thus decomposition of an object to be treated such as dioxins and organic substances that are hardly biodegradable is promoted, and an efficient purification treatment can be performed.

[Brief description of the drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

[Explanation of symbols]

 1: Raw water tank 2: Pressurized supply pump 3: Pressurized ultraviolet irradiation device 4: Ozone generator 5: Sealed column 6: Ultraviolet lamp 8: Gas-liquid separator

Claims (2)

[Claims] An ozone generator for producing an ozonized gas,
A pressurized supply pump for the water to be treated and a pressurized ultraviolet irradiation device with an ultraviolet lamp installed inside are provided. The ozonized gas generated by the ozone generator is supplied to the treated water supply pipe on the suction side of the pressurized supply pump. A water treatment apparatus comprising: an ozone supply pipe for supplying water; and a pressurized ultraviolet irradiation device connected to a water supply pipe for dissolving ozone on the discharge side of a pressurized supply pump. 2. An ozonized gas generated by an ozone generator is supplied from an ozone supply pipe to a treated water supply pipe on a suction side of a pressurized supply pump to mix the treated water and the ozonized gas to form an ozonized gas. The water to be treated, in which the gas is mixed and the ozone is dissolved, is supplied to the pressurized ultraviolet irradiation device from the treated water supply pipe on the discharge side of the pressurized supply pump, and irradiated with ultraviolet light under pressure in the pressurized ultraviolet irradiation device. Water treatment using ozone and ultraviolet light.