JP2001347295A - Apparatus for cleaning seawater containing floating substance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seawater cleaning apparatus simple and small-sized in the constitution, easily controlled in operation and capable of shortening a treatment time. SOLUTION: A liquid to be cleaned is introduced into the flocculating and stirring tank 23 of a pressure float separation apparatus 22 to be subjected to flocculation treatment and the formed floes are floated by air bubbles in a floating tank 24 to be removed as scum by a scum rake 26. Subsequently, the treated liquid is filtered under membrane osmosis pressure in a membrane treatment apparatus 52 to be separated into clarified seawater and unclear seawater. Further, the clarified seawater is oxidized in an UV oxidizing apparatus 58 and the chemical oxygen demand(COD) thereof is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a purification device for removing suspended substances such as jellyfish and pollutants in seawater, and is particularly suitable for a thermal power plant, a steel mill, an oil refinery, a petrochemical plant, a chemical plant, and the like. The present invention relates to a device for purifying seawater containing suspended substances.

[0002]

2. Description of the Related Art In power plants and the like, seawater is taken as cooling water, and this seawater sometimes contains suspended matter composed of organic substances such as jellyfish, red tide, and blue-green algae. Since seawater containing such substances is in a eutrophic state in which the suspended solids (SS) and chemical oxygen demand (COD) are increased, in order to use this as cooling water, the suspended solids and the like must be used in advance. It is necessary to remove and purify it. Therefore, generally, the first method to introduce seawater is
A purification device for removing and purifying these substances in stages is provided. FIG. 1 shows an outline of the power plant system. In the figure, reference numeral 1 denotes a purification device, and 2 denotes a power plant. The seawater 3 is supplied to the purification device 1 and used for cooling water of the power plant 2 after removing suspended matters.

FIG. 2 shows a configuration of a conventional purification device used in the above-described power plant system and the like.

[0004] Seawater 3 is introduced into a raw water tank 5 by a pump 4. The seawater 3 introduced into the raw water tank 5 is further guided to a nitrification tank 7 for biological treatment by a pump 6. The nutrient 7 is introduced into the nitrification tank 7, and a treatment with microorganisms is performed. Further, the seawater 3 is subjected to a denitrification treatment in a denitrification reactor 10 into which methanol has been introduced from a methanol injection device 9, and further passes through a re-aeration tank 11 in a tank 11 in which bubbles are formed, and enters a sedimentation tank 12. Sent. Settling tank 12
In this method, suspended substances are settled by their own weight, the supernatant is sent to the sand filtration device 13 and the filtered seawater is collected by the activated carbon adsorption device 14.
And then backwashed and discharged as treated water.

As described above, the conventional purification apparatus purifies seawater by combining a plurality of stages of sedimentation treatment, biological treatment, and chemical treatment, or uses any of these treatments alone.

[0006]

However, since the conventional purification apparatus needs to perform a precipitation treatment, a biological treatment, and a chemical treatment, a large-scale apparatus for performing these treatments and a large installation area are required. Needed. In addition, there are inconveniences that the operation management is relatively difficult to perform the biological treatment, and that the treatment requires time. Also,
When the apparatus including the biological treatment section is operated for the purpose of removing jellyfish, the operation is performed only in summer. For this reason, the facilities are idle in autumn and winter, and when the season comes, it takes a long time (approximately one month) to start the biological treatment, and there is also an inconvenience of lack of mobility. Further, in order to perform these treatments, it takes time for the facilities to be overwhelmed, so that there is a problem that the water to be treated is spoiled and the working environment is deteriorated.

An object of the present invention is to provide a seawater purification apparatus which can be simplified and reduced in size as a whole, can be easily operated, and has a high processing time.

[0008]

The present invention has the following arrangement to solve the above-mentioned problems.

(1) A storage tank for temporarily storing the obtained seawater as a liquid to be purified, an air bubble generator for introducing air bubbles into the storage tank, and causing a floating substance to adhere to the air bubbles to float in the storage tank, A separation unit that removes the floating substances that have floated, a pressurized flotation apparatus, and a liquid to be purified from which the suspended substances have been removed by the pressure flotation apparatus are filtered by membrane osmotic pressure to obtain clear seawater and non-clear seawater. And a oxidizing apparatus for oxidizing the clarified seawater. In the present invention, the suspended substance is caused to adhere to the air bubbles to float, and is removed by the separation unit. This operation is different from sedimentation treatment, biological treatment, and chemical treatment because it is a physical action of forcibly generating air bubbles and causing a floating substance to adhere to and suspend the air bubbles. In the next step, the liquid to be purified from which suspended solids have been removed is subjected to physical treatment to separate the clarified seawater from the non-clarified seawater by filtration with a membrane osmotic pressure. Does not include treatment or chemical treatment. In the next step, the oxidation of clear seawater is performed to reduce the chemical oxygen demand (COD). Since this oxidation treatment only oxidizes organic substances, a large apparatus such as a precipitation tank is not required.

As described above, according to the present invention, no large-scale equipment such as a sedimentation tank is required, and a long time is not required for the treatment and the operation management is not complicated and complicated.

(2) The oxidation treatment device oxidizes the clarified seawater by irradiating the clarified seawater with ultraviolet rays.

By oxidizing organic substances in the liquid to be purified by ultraviolet rays, the apparatus can be reduced in size and the processing speed can be increased.
Easy implementation can be realized.

(3) The oxidation treatment device oxidizes the clear seawater by injecting ozone into the clear seawater.

By injecting ozone into the liquid to be purified, the oxidation of organic substances can be promoted. The structure is also simple because only an ozone injection device is provided, and miniaturization and high-speed processing can be realized.

(4) The film processing apparatus is provided before the film processing apparatus,
A flocculation group was set up to flocculate suspended substances in seawater by introducing a chemical such as a flocculant into a tank for storing seawater.

In the present invention, the seawater is once collected in the coagulation part,
Then, it is introduced into a pressure flotation device. The aggregating section forms flocs by aggregating suspended substances, and aims to increase the efficiency of processing in a subsequent step. In other words, by guiding the flocs to the pressurized flotation device, the adhesion of the flocs to the air bubbles is promoted, and as a result, the amount of floating substances that float can be increased.

(5) A temporary storage group of seawater is provided between the pressure flotation device and the membrane treatment device.

The pressure flotation device and the membrane treatment device separate and remove suspended substances by physical action, respectively. The processing speed is settled, biological treatment, and chemical treatment to remove suspended substances. It is much faster than conventional devices. For this reason, if there is a difference in processing speed between these two devices, processing efficiency will be reduced. Therefore, in the present invention, a temporary storage section of seawater is provided between the pressurized flotation apparatus and the membrane processing apparatus, and the temporary storage section is used as a buffer. As a result, even if there is a difference in processing speed between these two devices, it is possible to mitigate a decrease in the overall processing speed due to the difference.

[0019]

FIG. 3 is a horizontal sectional view of a seawater purification apparatus according to an embodiment of the present invention.

Seawater is introduced into the raw water tank 20 from a pump (not shown), and the liquid to be purified is supplied from the raw water tank 20 to the raw water pump 21.
More water is taken. The liquid to be purified, which has been taken, is guided to the pressure flotation device 22. The pressure flotation / separation device 22 includes a coagulation stirrer tank 23, a flotation tank 24, a bubble water production device 25,
And a scum rake 26.

The simulated stirring tank 23 includes a rapid stirring tank 23a.
And a slow stirring tank 23b.
3a, a pseudo-collector 27 containing salt iron and caustic soda 29 are supplied by a pump 28 and a pump 32, and a slow stirring tank 23 is provided.
A polymer flocculant 31 is supplied to b by a pump 32. The simulating agent 27 appropriately aggregates organic substances in order to effectively float the scum in the floating tank 24 at the subsequent stage. The caustic soda 29 is supplied as a neutralization rate for adjusting pH.
Further, the polymer flocculant 31 functions as a flocculant, and enhances the efficiency of scum generation. Further, a stirring blade 33 is arranged in the rapid stirring tank 23a, and a stirring blade 34 is arranged in the slow stirring tank 23b.

The bubble water producing apparatus 25 generates ultrafine bubbles, and introduces the bubbles into the floating tank 24 together with the liquid to be purified from the collection and stirring tank 23. These are preferably introduced from the bottom of the floating tank 24, whereby the aggregates (organic substances) in the liquid to be purified sufficiently adhere to the surface of the bubbles during the period until the bubbles float, and the liquid components as scum are mixed with the liquid components. Separated.

A plate-shaped scum lake 26 is disposed above the floating tank 24 so as to be rotatable along the liquid surface.
The motor 33 rotates the scum lake 26, and the scum lake 26 rotates on the liquid surface of the floating tank 24, thereby scooping the scum floating on the liquid surface and discharging the scum to the scum take-out port 35. This scum outlet 3
The scum discharged to 5 is discharged to a scum tank 34 by a scum discharge pipe 36. As a result, a considerable amount of solid organic matter contained in the liquid to be purified is separated and discharged.

FIG. 4 shows a state in which air bubbles adhere to the aggregates in the floating tank 24. Many ultra-fine bubbles 38 are mixed in the liquid component 39, and aggregates 37 adhere to the surface of the bubbles 38. As shown in FIG.
Since the volume of the aggregate 35 is considerably smaller than that of the aggregate 35, the aggregate 3
A plurality of bubbles 36 contact 5. Therefore, the buoyancy of the aggregate can be sufficiently increased, and these can be collected on the liquid surface and extracted as a scum of a large lump of the aggregate.

The liquid to be purified from which the scum has been removed in the floating tank 24 is once discharged into a liquid-to-be-purified storage section 40, and a part thereof is guided to the bubble water producing apparatus 25 by the pump 41. For this reason, the bubble water supplied to the floating tank 24 has ultrafine bubbles formed in a clean liquid from which scum has been removed.

The to-be-purified liquid in the to-be-purified liquid storage section 40 is guided to a treated water storage tank 50. This storage tank 50
Processing speed of pressure flotation device 22 and subsequent membrane processing device 5
2 functions as a buffer that functions to absorb the difference in processing speed. Pressure flotation device 22 and membrane processing device 52
Are both physical processes that do not use sedimentation equipment and the like, and therefore have a high processing speed. Therefore, by providing the storage tank 50, it is possible to absorb the difference in the processing speed.

The liquid to be purified once stored in the treated water storage tank 50 is guided to a membrane treatment device 52 by a pump 51. This apparatus separates clear seawater and non-clear seawater by filtering seawater from which suspended substances have been removed by the pressurized flotation device with a membrane osmotic pressure. The membrane processing device 52 includes a raw water tank 53,
Pump 54 for taking out the liquid to be purified stored in the raw water tank
And a module 55 for introducing the liquid to be purified taken out by the pump 54 to separate clarified seawater and non-clarified seawater by osmotic pressure, and a compressor 56 for pushing out organic substances adhering to the membrane surface by air. And The contaminated liquid containing organic substances on the membrane surface is drained into the backwash drain tank 57. Further, filtration drainage and drain drainage are also performed for the backwash drainage tank 57.

The UV oxidizing device 58 oxidizes the liquid to be purified from which organic substances have been removed as described above by irradiating it with ultraviolet light.
Performs oxidative decomposition of chemical oxygen demand (COD) derived from organic matter. The UV oxidizing device 58 only irradiates the liquid to be purified with ultraviolet light, and therefore does not become large-scale.

With the above structure, the seawater taken into the raw water tank 20 can be used as a suspension of organic matter (SS) by the following steps.
Is removed and the chemical oxygen demand (COD) is reduced.

First, seawater is floc-formed by the coagulation and stirring tank 23. The flock floats and becomes scum by adhering to the air bubbles in the floating tank 24, and the scum lake 2
6 removed. At this stage, a considerable amount of suspended solids (SS) contained in the liquid to be purified (seawater) is removed.

Next, the liquid to be purified from which the suspended substances (SS) have been removed in this manner is separated into clarified seawater and non-clarified seawater in the membrane treatment device 52 by osmotic pressure. The non-clear seawater is drained as filtered water into the backwashing drainage tank 57, and only the clearing seawater is taken out. This process also removes very fine suspended solids (SS).

In the next stage, the liquid to be purified from which most of the suspended solids (SS) have been removed is oxidized by irradiation with ultraviolet light,
Chemical oxygen demand (COD) is reduced.

FIG. 5 shows the reduced state of the suspended solids (SS) and the chemical oxygen demand (COD) in each step by the above-mentioned apparatus. Even at the stage when the process of the film processing apparatus 52 of the third process is completed, the concentration is reduced from 430 mg / L to 70 mg / L or less. Performing the fourth step of UV oxidation reduces the chemical oxygen demand (COD) to <50 mg / L.

It is to be noted that other oxidizing means can be used in place of the UV oxidizing device 58. For example, it is possible to oxidize the clear seawater by injecting ozone into the clear seawater. Such a device also does not become overwhelming because it only oxidizes clear water.

[0035]

According to the present invention, the use of a pressure flotation apparatus and a membrane processing apparatus having a small apparatus and a high processing speed does not require a large-scale facility such as a sedimentation tank.
No long processing time is required. Also, since no microorganisms are used, operation management is easy.

Further, by oxidizing the organic substances in the liquid to be purified with ultraviolet rays or ozone, it is possible to easily realize the miniaturization of the apparatus and the high-speed processing.

In addition, seawater can be once collected in a flocculation section and then introduced into a pressure flotation device.

Further, by providing a temporary storage of seawater between the pressure flotation device and the membrane processing device, even if there is a difference in the processing speed between these two devices, the overall processing speed can be increased. Can be prevented from decreasing.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a power plant system to which a seawater purification device is applied.

FIG. 2 is a configuration diagram of a conventional seawater purification system.

FIG. 3 is a configuration diagram of a seawater purification device according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of the pressure flotation device.

FIG. 5 is a diagram showing a reduction state of SS and COD in a name process.

[Explanation of symbols]

 22: Pressurized flotation device 23: Coagulation stirrer tank 24: Flotation tank 25: Bubble water production device 52: Membrane treatment device 58: UV oxidation device

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) C02F 9/00 502 C02F 9/00 502R 502Z 503 503A 1/24 1/24 C 1/32 1/32 1/44 1 / 44 H 1/52 1/52 K 1/56 1/56 K 1/72 101 1/72 101 1/78 1/78 (72) Inventor Akira Torii 3-3-22 Nakanoshima, Kita-ku, Osaka Kansai Inside Electric Power Company (72) Inventor Tetsuro Sakashita 3-3-22 Nakanoshima, Kita-ku, Osaka City Inside Kansai Electric Power Company (72) Inventor Masayuki Watanabe 1-7-131 Nishimiyahara, Yodogawa-ku, Osaka Izumi Electric Co., Ltd. Inside the company (72) Inventor Katsuyuki Machiya 1-7-31 Nishinomiyahara, Yodogawa-ku, Osaka-shi Inside Izumi Electric Co., Ltd. Term (reference) 4D006 GA03 JA67A KA02 KA71 KB04 KB13 KB30 KC03 KC14 KD21 PA01 PB03 4D015 BA19 BA24 BB08 BB12 CA18 CA20 DA13 DB01 DC02 EA07 EA15 EA33 FA02 FA17 FA24 4D037 AA06 AB01 AB02 BA03 BA18 BB07 CA03 CA08 CA12 CA14 4D050 AA06 AB07 BB01 BB02 BC09 BD06 CA04 CA09 CA13 CA16 4D062 BA19 BA24 BB08 BB12 CA18 CA20 DA13 DB01 DC02 EA07 EA15 EA33 FA02 FA17 FA24

Claims (5)

[Claims] 1. A storage tank for temporarily storing the obtained seawater as a liquid to be purified, a bubble generator for introducing air bubbles into the storage tank and causing a floating substance to adhere to the air bubbles to float in the storage tank, A separation unit that removes suspended substances that have been removed, a pressurized flotation device, and a liquid to be purified from which suspended substances have been removed by the pressurized flotation device are filtered by membrane osmotic pressure to obtain clear seawater and non-clear seawater. An apparatus for purifying seawater containing suspended solids, comprising: a membrane treatment apparatus for separating; and an oxidation treatment apparatus for oxidizing the clear seawater. 2. The apparatus for purifying seawater containing suspended substances according to claim 1, wherein the oxidation treatment apparatus oxidizes the clearwater by irradiating ultraviolet light to the clearwater. 3. The apparatus for purifying seawater containing suspended substances according to claim 1, wherein the oxidation treatment apparatus oxidizes the clarified seawater by injecting ozone into the clarified seawater. 4. An aggregating unit which is provided at a preceding stage of the membrane processing apparatus and which agglomerates a floating substance in seawater by charging an aggregating agent into a tank for storing seawater. An apparatus for purifying seawater containing suspended substances according to the present invention. 5. The apparatus for purifying seawater containing suspended substances according to claim 1, wherein a temporary storage section of seawater is provided between the pressure flotation device and the membrane treatment device.