JP2838149B2 - Water purification method and water purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial application field" The present invention relates to water quality because the natural water level fluctuates with the sea surface due to natural tidal action, but natural circulation of seawater hardly occurs up to the inner part. Water areas where deterioration may occur,
For example, the present invention relates to a water purification method and a facility for purifying water applied to closed sea areas such as canals and harbors provided in coves and harbors of the bay (hereinafter, such sea areas are appropriately referred to as closed sea areas).

2. Description of the Related Art Conventionally, in the case of purifying seawater in a closed sea area such as a canal provided in an inland sea such as a bay or a bay, or a harbor or the like, the seawater outside the closed sea area is confined by purifying the seawater. There are many methods of exchanging seawater in a marine area. For example, in a port, it has been conventionally performed to improve the exchange rate of seawater by expanding a port entrance or changing its position.

"Problems to be solved by the invention" However, in a closed sea area with an elongated shape such as a canal, the seawater is exchanged due to tide at the estuary, but the exchange efficiency is very poor. For,
At present, almost all areas except the estuary are stopped and the water quality is extremely degraded. In order to purify the water quality in such closed water areas, it is considered necessary to replace the seawater using the power of a pump or the like. Currently, in canals and the like, almost no water conveyance method has been used, and only internal load reduction by removing bottom mud has been performed.

In recent years, especially in closed metropolitan areas such as canals in large metropolitan areas, water quality has been improved to a level where water can be "touched", thereby creating an environment in which living space (people) and nature are in harmony. Is widely desired by the public, and in that case, the running costs associated with seawater exchange in the enclosed water area are minimized by efficiently using the tide outside the enclosed water area. Hold it down,
It was also desired to maintain the characteristics of the sea by causing a water level change in conjunction with the tide level change due to the tide in the enclosed sea area.

However, the water quality in the bays of metropolitan areas, which are seas close to most of the people, is hardly good. Therefore, seawater in closed sea areas such as canals is exchanged by conducting water from such bays. Even so, it is not possible to expect the water purification effect of water conveyance by water conveyance from the surrounding waters of the same degree of contamination.Therefore, means for satisfying the longing for the waterfront, which is increasing as the needs of the people, are still being devised. It was not at the moment.

The present invention has been made in view of the above circumstances, and is applied to a closed water area, such as a canal, which is unlikely to be exchanged with seawater in a natural state, so that water in the water area can be efficiently used as seawater in the surrounding sea area. It is an object of the present invention to provide a water purification method and a water purification apparatus that can be exchanged well and can expect an extremely good water purification effect even when the water quality in the surrounding sea area is poor.

"Means for solving the problem" The water purification method of the present invention is adapted to a water area which is open to the sea and whose water level fluctuates with the sea level due to natural tidal action. A sluice is provided to partition the sea area, and an intermediate weir is provided to divide the water area into a deep part and a sluice-side part.At high tide, the sluice is closed to bring the water level of the water area higher than the sea level of the surrounding sea area. As well as ensuring a water level difference that is maintained relatively low, the intermediate weir is closed and a water level difference can be secured between the back and the gate side, and in that state, the surrounding sea area and the Utilizing the water level difference with the back of the water area, the seawater in the surrounding sea area is taken into the purification waterway, purified by the purification device provided in the middle of the purification waterway, and the purified seawater flows down the purification waterway naturally. By the said water area The water level is higher than the water level of the floodgate side part, and then the intermediate weir is opened to make the water level of the whole water area constant, and the sea level is higher than the water level in the water area. At the time of low tide, when the floodgate is opened with the intermediate weir closed, water at the floodgate side of the water area is discharged to the surrounding sea area through the floodgate.

Further, the water purification equipment of the present invention is for implementing the water purification method, and separates the water area from the surrounding sea area to maintain a water level difference that maintains the water level of the water area lower than the sea level. A lock that can be secured, an intermediate weir that can secure a water level difference by partitioning the water area into a deep part and a part on the floodgate side, and extending from the surrounding sea area to the deep part of the water area, and A purified water channel which can be discharged at the back of the water area by taking in seawater in the surrounding sea area and allowing the water to flow naturally when the water level difference is secured between the purified water path and the purified water path provided in the purified water path A purification device that purifies the seawater taken in the purification water passage while flowing down the purification water channel, wherein the purification device has an inflow portion provided with a sedimentation tank portion that sediments and separates sludge, and a contact material is loaded. Storage tank with many connected storage tanks When, characterized by comprising; and a water channel provided with a aeration device.

"Action" The present invention is directed to a closed water area where water stagnates in the natural state and the water quality is likely to deteriorate, and the water in the water area is effectively used by utilizing a tidal level difference due to tide which is natural energy. By efficiently exchanging with the seawater in the surrounding sea area and discharging the seawater in the surrounding sea area to the target water area while purifying the same, an extremely good water quality purification effect can be obtained even when the water quality in the surrounding sea area is poor.

That is, in the present invention, the water level of the target water area is maintained lower than the sea level of the surrounding sea area by closing the water gate at high tide, and at that time, the middle weir is also closed, so that the inner part of the water area and the part on the water gate side are closed. And water level difference can be secured. In this state, the seawater in the surrounding sea area is taken into the purification channel by the water level difference between the surrounding sea area and the back of the water area, and the taken seawater is purified by the purification device in the purification channel and discharged to the back of the water area. Thereby, the water level in the water area is raised by the purified seawater, and when the water level reaches a predetermined water level, the intake of seawater from the surrounding sea area is stopped. Then, open the intermediate weir to keep the water level of the whole water area constant. Then, at low tide, the intermediate weir is closed, and by opening the lock, the water on the lock side in the water area is discharged from the lock to the surrounding sea area, and the lock is closed when the water level falls to a predetermined water level.

In this way, the clean seawater introduced into the inner part of the water area flows from the inner part toward the sea side and is discharged to the surrounding sea area, and the intermediate dam causes a difference in water level between the inner part and the part on the floodgate side. Since the introduction and discharge of the seawater are performed while securing the seawater, the seawater is surely and uniformly exchanged over the entire area of the water body, whereby the water in the water area is efficiently exchanged.

Moreover, not only the water in the water area is simply exchanged for seawater, but also the seawater withdrawn is subjected to contact aeration treatment by a purification device equipped with a sedimentation tank, a storage tank, and an aeration device to be surely and sufficiently purified. By exchanging with such purified seawater, the water purification effect in the water area becomes extremely high.

Note that a large difference in water level (difference in ebb and flow) at the back of the water area can be ensured by the opening and closing operation of the intermediate weir as described above. In other words, when seawater is introduced into the body of water without an intermediate weir, the water level of the whole water area rises only slightly.However, if seawater is introduced into the area with the inner weir partitioned by the intermediate weir, the water level rises. Can be larger.

"Example" Hereinafter, in describing an example of the present invention, a basic principle and an outline of the present invention will be described.

Note that the water area targeted for purification by the present invention is a closed water area such as a canal that is open to the sea as described above, but does not easily cause natural circulation of seawater. The water area targeted for purification in the present invention is referred to as “closed sea area” for convenience. However, in this embodiment, the term "closed sea area" does not mean that the purification target water area is always kept in a closed state with respect to the surrounding sea area. In this connection, the sluice gate is opened and closed as appropriate, and when the sluice gate is opened, it opens to the surrounding sea area.

In general, the natural purification action in a sea area is that the pollution degree of the sea area is reduced by natural conditions due to the ingestion of pollutants by living organisms, dilution with seawater, diffusion and migration to other sea areas, etc. In marine areas, the reliance on pollutants by living organisms is highly dependent. A contact aeration method is known as a water treatment method that artificially promotes the purifying action of living organisms. This contact aeration method has been increasing in recent years in the purification of rivers, but from the following points, it seems that it can exert a sufficient water purification effect on purification of seawater in closed sea areas. It is.

(1) In seawater in closed sea areas such as canals, most of the polluting substances are from domestic wastewater (undegraded substances in sewage treatment water), or living bioplankton and its dead bodies. And other organic substances.

(2) The contact aeration method is sufficiently effective in treating human waste by diluting it with seawater, purifying water in a sea aquarium, or purifying some canal water.

Therefore, the present invention has focused on applying the contact aeration method (contact precipitation method) to seawater purification. That is, in the present invention, the seawater taken in from the surrounding sea area of the closed sea area is aerobically purified by the microbial membrane attached to the surface of the contact material installed in the natural flow type purification water channel. In this case, an underwater fan (which ensures contact speed) and a blower (which stirs seawater to send dissolved oxygen) and a blower (which dissolves dissolved oxygen) are placed at appropriate places in the purification waterway, so that the contact speed between seawater and the contact material and seawater Keep the dissolved oxygen above the required limit. Then, by purifying the seawater in this manner, adsorption and removal of SS content in the seawater, decomposition of soluble organic substances, and nitrification of a part of NH ₄ —N (ammoniacal nitrogen) are performed.

However, the water purification system for closed sea areas according to the present invention includes:
Its function is fully exerted by providing it in a closed sea area that is adjacent to the surrounding sea area where the tide level difference is 0.5 m or more (preferably 0.8 m or more), and it should be installed in such a closed sea area. Thus, while maintaining the composition of seawater in the enclosed sea area similar to that of the surrounding sea area, the quality of the water is improved to be better than that of the surrounding sea area.

Next, an embodiment of the water purification equipment of the present invention will be described with reference to FIGS.

The water purification equipment of this embodiment is, as shown in FIG.
It is for purifying the water quality in the closed sea area 1 by exchanging the seawater in the closed sea area 1 with the seawater in the surrounding sea area 2, and provided at the estuary 3 of the closed sea area 1. An openable and closable sluice gate 4 for dividing the sea area 1 from its surrounding sea area 2 and an openable and closable weir 6 provided at an intermediate portion of the closed sea area 1 and separating the estuary part 3 and the back part 5 of the closed sea area 1. A box culvert-type purified water channel 7 extending from the peripheral sea area 2 to the inner part 5 of the closed sea area 1 and purifying the seawater in the peripheral sea area 2 and discharging the sea water to the inner part 5 of the closed sea area 1. It is composed of

The closed sea area 1 is a canal that extends linearly from the estuary portion 3 that continues to the surrounding sea area 2 across the sluice 4 toward the back of the land 8, and the canal is bent at the back portion 5 and is located at the back. An artificial tidal flat 9 is provided in the area. The tideland 9 is a sandy land provided for promoting the natural purification action in the closed sea area 1 and is used to ingest contaminants in seawater in the closed sea area 1 to organisms such as shellfish. Further, the water is exposed above the water surface or sinks below the water surface due to a change in the water level in the closed sea area 1.

The intermediate weir 6 provided in the middle of the closed sea area 1 is submerged in the water bottom of the closed sea area 1 as shown in FIGS. 2 (a), 2 (b) and 2 (c). It is composed of the constructed concrete weir 10, and an air-injection type rubber balloon type rubber weir 12 fixed in a concave part 11 provided on the upper part of the concrete weir 10, and the inside of the rubber weir 12 The water level is adjusted by changing the amount of air. It is not always necessary to use the intermediate weir 6 provided with the rubber weir 12, but such a rubber weir 12 can provide safety (reliability), operability, and maintenance and management when the water level adjustment width is small. Comprehensive evaluation from the viewpoint of easiness, economy, durability, etc., is suitable for use as the intermediate weir 6 in the closed sea area 1. In addition, this intermediate weir 6
And the floodgate 4 may be provided with a double floodgate, respectively.
In this case, a maintenance ship and an emergency ship in the closed sea area 1 can enter and exit freely.

As shown in FIG. 1, the washing channel 7 is composed of a box culvert type channel extending from the estuary 3 to the back 5 in parallel with the closed sea area 1 and a purification device therein. One end of the estuary 3 is connected to an external intake 13 installed in the surrounding sea area 2 outside the floodgate 4, and the other end is floated in the innermost part 5 of the closed sea area 1. It is connected to a floating island 14 having a water outlet. One end of the purified water channel 7 on the estuary 3 side is connected not only to the external intake 13 outside the gate 4 but also to the internal intake 15 installed at the estuary 3 inside the gate 4. Are linked.

As shown in FIGS. 3 and 4 (a sectional view taken along the line AA in FIG. 3), the internal structure of the purification water channel 7 allows the seawater in the surrounding sea area 2 to be taken in from the outside water intake 13. An inflow portion 16 for storing, a storage tank portion 17 for storing and purifying the seawater flowing from the inflow portion 16, and a deep portion 5 of the closed sea area 1 while purifying the seawater stored in the storage tank portion 17. It is composed of a natural flow-down type waterway 18 released from the floating island 14.

The inflow section 16 has a sex control valve 19 that controls the amount of seawater taken in from the external water intake 13, and a screen 20 that separates foreign substances mixed in seawater flowing through the control valve 19. And a sedimentation tank 21 for sedimenting and separating sludge from the seawater passing through the screen 20, and as shown in FIG. 5 (a sectional view taken along the line BB in FIG. 3),
The settling tank section 21 is equipped with a sludge discharging device 22.

In the storage tank section 17, a plurality of storage tanks 23 are arranged vertically and horizontally adjacent to each other, and inside each storage tank 23, a contact material 24 to which a microbial membrane is attached is loaded,
While purifying the seawater flowing into each of the storage tanks 23 located on the inflow section 16 side in each of the storage tanks 23, each of the storage tanks 23 on the downstream side thereof (a cross section orthogonal to the flow direction of the seawater in FIG. 6) Indicates)
All the storage tanks 23 are filled with seawater by sending them out.

The natural flow-down channel 18 includes a box culvert 25 extending from the downstream side of the storage tank section 17 to the floating island 14, a contact material 26 loaded in the box culvert 25, and a lower part of the box culvert 25. Installed in seawater contact material
A submersible fan 27 for providing a contact speed with the air circulator 26;
28, wherein a box 29 is formed at the bottom of the box culvert 25. (FIG. 7 shows a cross section orthogonal to the flow direction of seawater.) Next, a water purification method using the water purification equipment having the above configuration will be described. First, at high tide (at high tide), the sluice 4 is closed, and then the control valve 19 of the inflow section 16 of the purified water channel 7 is opened at an appropriate opening. In this way, the seawater in the surrounding sea area 2 flows into the inflow section 16 of the purification waterway 7 from the external intake port 13 due to the water level difference between the surrounding sea area 2 and the closed sea area 1, and then from the inflow section 16 to the storage tank section. The water flows into the storage tanks 17 and is sequentially sent out to the adjacent storage tanks 23 in the storage tank section 17, so that the water is purified when passing through each storage tank 23 and temporarily stored in all the storage tanks 23. The seawater thus stored in each storage tank 2 flows into the free-flowing waterway 18 and flows to the floating island 14 by natural flow while being purified in the free-flowing waterway 18. That floating island
Water is discharged from the 14 outlets to the inner part 5 of the closed sea area 1.
Then, in this way, by raising the water level in the closed sea area 1 by discharging water from the floating island 14 and stopping the introduction of seawater from the surrounding sea area 2 when the water level reaches a predetermined water level, At the same time, the water discharge from the floating island 14 is stopped.

Further, a sluice 4 is provided downstream of the closed sea area 1, and the water level in the closed sea area 1 is adjusted by opening and closing the sluice 4. That is, when the quality of the seawater in the surrounding sea area 2 is not good, or when it is determined that the seawater in the surrounding sea area 2 should not be taken into the closed sea area 1 due to weather or sea conditions, the sluice 4 is closed and the purified water channel 7 is closed.
When the closed sea area 1 is isolated from the sea in the surrounding sea area 2 and the quality of the sea water in the surrounding sea area 2 is good, the sluice 4 is opened to take the sea water from the surrounding sea area 2 into the purification channel 7.
In addition, a tidal flat 9 is located near the floating island 14 at the back 5 of the closed sea area 1.
However, in order to make the difference between the tidal flats in the tidal flat 9 as large as possible, an intermediate weir 6 is provided in the center of the closed sea area 1, and the level of the tidal flat 9 is adjusted by operating the intermediate weir 6. To do it.

Next, a method of controlling the water level in the closed sea area 1 will be described.
The description will be made in three stages: water intake, descent of the intermediate weir, and water discharge.

(1) Water intake: As described above, when the tide level in the surrounding sea area 2 is high, the seawater in the surrounding sea area 2 is taken in from the external intake port 13 and flows down naturally in the purified water channel 7 to discharge the water from the floating island 14. From the closed sea area 1 to the inner part 5. In this case, as shown in FIG. 2 (a), an intermediate weir 6 in the middle of the closed sea area 1 is used.
Rises and the middle weir 6 blocks the middle part of the closed sea area 1, so that the closed sea area 1 is closed.
The water level at the inner part 5, ie, the upstream side of the middle weir 6, rises by about 0.2 m by the above-mentioned water intake, but the water level at the estuary part 3 of the closed sea area 1, ie, the downstream side of the middle weir 6, does not change. The water level is maintained at about 0.3 m lower than the water level on the upstream side of the raised intermediate weir 6. In order to cause such a water level change, for example, the total water amount in the closed sea area 1 is set to 1,014,
In the case of 000 m ³ , the daily water intake to be taken into the closed sea area 1 is 16,900 m ³ .

(2) When the intermediate weir descends: the closed sea area 1 as described above
When the intermediate weir 6 is lowered as shown in FIG. 2 (b) after raising the water surface of the deep part 5 of the sea, the water level difference between the deep part 5 and the estuary part 3 in the closed sea area 1 ( about 0.3 m) will flow seawater inner part 5 to the mouth portion 3 by, when the seawater flows 16,900M ^3, the water level in the inner part 5 is about 0.2m decrease, the water level of the river mouth portion 3 is about
After rising 0.1 m, the water level in the entire closed sea area 1 becomes the same and balances.

(3) At the time of water discharge: After balancing the water level at the back part 5 of the closed sea area 1 and the water level at the estuary part 3 as described above,
As shown in FIG. 3C, the intermediate weir 6 is raised again to close the closed sea area 1 at a midpoint thereof, and then when the tide level of the surrounding sea area 2 is low (at low tide), By opening the floodgate 4 and discharging 16,900 m ³ / day, the water level at the estuary 3 (downstream of the intermediate weir 6) of the closed sea area 1 is lowered by about 0.1 m. (Thus, the water level at the estuary 3 is lower than the water level at the depth 5 by 0.1 m.) The operation of the sluice 4, the intermediate weir 6, the external intake 13, and the internal intake 15 depends on the closedness. In the sea area 1, the surrounding sea area 2
Automatically controls so as to produce a change as similar as possible to the tide level change due to the tide. Table 1 below shows sensors required for performing the automatic control, types of data (status reports such as weather and sea conditions), and installation locations of the sensors.
Also, the installation location is displayed in FIG. 1 using the symbols shown in the installation location column of Table 1.

Regarding the opening and closing operations of the external intake 13 and the internal intake 15, the turbidity meter, DO sensor, pH sensor, wave height meter, and red tide occurrence report installed in front of the external intake 13 (or outside the gate 4) Data such as a blue tide occurrence report, an abnormal weather report, an emergency report, and the like are input to the integrated monitoring center, and are automatically performed while controlling based on the information. For example, the operation of the sluice gate 4 is performed based on information from a tide gauge and a water gauge in front of the external intake 13, whereby the water levels of the deep part 5 and the estuary part 3 in the closed sea area 1 are respectively adjusted to appropriate levels. To control. When the quality of the seawater in the surrounding sea area 2 is extremely poor, the external water intake 13 is closed to stop the exchange of the seawater in the surrounding sea area 2 with the seawater in the closed sea area 1. Further, even when the external conditions such as weather and sea conditions are poor, the external water intake 13 is fully closed based on the data of the respective status reports to stop water intake from the sea in the surrounding sea area 2. In addition, the operation of the intermediate weir 6 is performed in the inner part 6 of the closed sea area 1.
Water level meter, flow meter, DO near floating island 14
This is performed based on information from the sensor and the pH sensor. In addition, when each of the above sensors is used, for example, based on information from the DO sensor, it is also possible to automatically aerate the purified water channel 7 when the DO in seawater falls below a certain level. .

The processing capacity of the purification device provided in the purification water channel 7 is shown below.

i. Treated water volume: 16,900 m ³ / day ii. Raw water quality ・ pH 7-8 ・ SS 3-10 mg / ・ COD 3-9 mg / iii. Treated water quality ・ COD 3-5 mg / ・ SS 3-5 mg / Although the above embodiment is an application of the present invention to a canal, the present invention is not limited to a canal but may be applied to internal water bodies such as small bays and coves, and as shown in FIG. When applied to downstream waters such as a canal or a river, it is not only applied near the estuary 3 but also applied upstream to the floodgate 30 (see FIG. 1) provided near the back 5. A two-stage water purification system may be configured, or a three-stage or four-stage water purification system may be applied to the upstream side. When a multi-stage water purification facility is configured in this way, a river or canal with improved water quality can be formed stepwise toward the upstream side.

[Effects of the Invention] As described above, the water purification method and the water purification equipment of the present invention exhibit the following excellent effects.

(1) Since the seawater is introduced into the target water area using the natural tidal action and the water in the target water area is exchanged with seawater, the self-purifying action of the target water area can be maintained and amplified, and the target water area can be maintained. The bottom quality of the water area can be improved.

(2) At the time of high tide, the sluice is closed to introduce seawater to the back of the target water area, and at low tide, the sluice is opened to discharge the water in the target water area from the sluice. The seawater is introduced and discharged while maintaining a water level difference between the water and the floodgate side, so that clean seawater introduced into the deep part of the body of water surely flows from the deep part toward the sea side to the surrounding sea area. It is possible to reliably and efficiently exchange the discharged and clean seawater over the entire body of water, and to surely improve the water quality of the entire body of water. Further, a large difference in water level at the back can be secured by opening and closing the intermediate weir.

(3) Since the seawater in the surrounding sea area is introduced into the target water area while being purified by the purification device, it can be adapted even when the water quality in the surrounding sea area is not good, and the water quality in the target water area can be improved to be better than the surrounding sea area. can do. Further, since the purifying device is based on the contact aeration method, it is possible to reliably and sufficiently purify seawater.

[Brief description of the drawings]

1 to 7 are views showing an embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a water purification apparatus of the present embodiment, and FIGS. 2 (a), (b), ( c) is an explanatory view for explaining the operation method of the sluice gate and the intermediate weir, FIG. 3 is a schematic configuration diagram of the purification water channel, FIG. 4 is a sectional view taken along the line AA of FIG. 3, and FIG. 6 is a sectional view taken along line CC of FIG. 3, FIG. 6 is a sectional view taken along line DD of FIG. 3, and FIG. 1 ... closed sea area, 2 ... surrounding sea area, 3 ... estuary, 4 ... sluice gate, 5 ... deep part, 7 ... purified water channel.

──────────────────────────────────────────────────続 き Continued on the front page (73) Patent holder 999999999 Taiyo Kogyo Co., Ltd. 4-84-4 Kikawahigashi, Yodogawa-ku, Osaka-shi, Osaka (73) Patent holder 999999999 Takenaka engineering works 8-chome, Ginza, Chuo-ku, Tokyo 21-1 (73) Patent holder 999999999 Toa Construction Industry Co., Ltd. 5 Yonbancho, Chiyoda-ku, Tokyo (73) Patent holder 999999999 Toyo Construction Co., Ltd. 4-1-1 Koraibashi, Chuo-ku, Osaka-shi, Osaka (73 ) Patent holder 999999999 Fujita Co., Ltd. 4-6-115 Sendagaya, Shibuya-ku, Tokyo (73) Patent holder 999999999 Fudo Construction Co., Ltd. 4-2-1-16 Hirano-cho, Chuo-ku, Osaka-shi, Osaka (73) Patent holder 999999999 Honma Gumi Co., Ltd. 3300-3, Tominomachi, Nishiminato-machi, Niigata City, Niigata Prefecture (72) Inventor Chiaki Niwa 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Construction (72) Inventor Kiyoshi Nikaido 3-4-7 Nishi-Shinjuku, Shinjuku-ku, Tokyo Kurita Water Industries Ltd. (72) Inventor Kiyoshi Nishihara 8-2-1-1, Ginza, Chuo-ku, Tokyo Co., Ltd. (72) Inventor Masakazu Imaizumi 4-6-115 Sendagaya, Shibuya-ku, Tokyo Inside Fujita Industries Co., Ltd. (56) References JP-A-58-20285 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C02F 1/00 C02F 3/12

Claims (2)

(57) [Claims] 1. Applicable to a body of water that is open to the sea and whose water level fluctuates with sea level due to natural tidal action,
A method for purifying water in the water area, wherein a water gate is provided to partition the water area and its surrounding sea area, and an intermediate weir is provided to partition the water area into a back part and a water gate side part. At high tide, the floodgate is closed to secure a water level difference that maintains the water level of the water area relatively lower than the seawater level of the surrounding sea area. Water level difference can be secured between
In this state, utilizing the water level difference between the surrounding sea area and the inner part of the water area, seawater in the surrounding sea area is taken into the purification waterway and purified by the purification device provided in the middle of the purification waterway, and the purified seawater is purified. By allowing the purified water channel to flow naturally, it is released to the inner part of the water area to make its water level higher than the water level of the sluice-side part, and then, by opening the intermediate weir, the water level of the entire water area is made constant. At low tide when the sea level is lower than the water level in the water area, the water is opened to the surrounding sea area through the water gate by opening the water gate with the intermediate weir closed. Water purification method. 2. A water purification apparatus for carrying out the water purification method according to claim 1, wherein the water area is maintained at a lower level than the sea level by partitioning the water area from the surrounding sea area. A sluice gate capable of securing a water level difference, an intermediate weir capable of securing a water level difference therebetween by dividing the water area into a deep part and a sluice-side part, and extending from the surrounding sea area to the deep part of the water area. And a purified water channel that can be discharged in the inner part of the water area by taking in seawater in the surrounding sea area and allowing the water to flow naturally when the water level difference is secured therebetween, and A purification device that purifies seawater taken into the purification water passage while flowing down the purification water passage, wherein the purification device has an inflow portion provided with a sedimentation tank portion that sediments and separates sludge, and a contact material is loaded. Many storage tanks And a reservoir unit, water purification equipment, characterized by comprising; and a water channel provided with a aeration device.