JP2961278B2 - Seawater purification structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is provided in a tidal flat in a semi-enclosed sea area, and is capable of purifying the sea water in the semi-enclosed sea area effectively and at low cost. It is about things.

[Related Art] In recent years, especially in semi-enclosed sea areas having tidal flats, beaches, and the like in metropolitan areas, landfills have rapidly progressed due to increasing social needs, and seawalls and embankments have been artificially formed on these watersides. Was. On the other hand, recently, in order to restore the nature of the semi-enclosed sea area and to enrich life, the quality of seawater in these sea areas has been improved to the extent that people can touch the water, and the natural environment has been improved. It is hoped to regain.

For example, since tidal flats are composed of clay, silt, sand, etc., they have a certain degree of water permeability, and the water permeability coefficient is 10 ^-5.
cm / sec. It is well known that this tidal flat has the effect of purifying seawater because the seawater contains microorganisms and benthic organisms that live in the particle gaps and surfaces of clay, silt, sand, etc., which are the constituents of the tidal flat. To purify seawater by decomposing organic substances and pollutants, etc., and to purify seawater by removing particles of seawater, such as clay, silt, and sand, because these particles have a filtering effect. It is. Of course, the decomposition rate of seawater-soluble contaminants varies considerably depending on the composition of water quality. However, in tidal flats, suspended solids (SS content) in the exchanged seawater are almost completely removed and purified. COD, TC, and the like caused by the substance are also removed and purified at the same time.

[Problems to be Solved by the Invention] By the way, as shown in FIG. 3, the amount of exchanged water in a general tidal flat is the daily minimum headline () in the tidal flat 2 starting from the low tide surface (LWL) of the semi-enclosed sea area 1. L) and a daily high water head line (H) in the tidal flat 2 starting from the high tide surface (HWL). Since the particle diameter of clay, silt, sand, etc., which is a constituent element of the tidal flat 2, is smaller than the particle diameter of sand, etc. on the sandy beach, it becomes difficult for seawater to penetrate into the tidal flat 2, and therefore, the daily maximum headline (H) However, there is a drawback that the slope tends to be steep and the actual exchange water amount of the tidal flat 2 is reduced. In this case, the permeability of the tidal flat 2 is extremely small.
The daily purification amount is said to be about 0.3 g / m ² / g-SS / day in COD, which means that the purification amount is only about one-fourth of the sand beach. Thus, if the amount of seawater exchange in the tidal flat 2 can be increased, the purification capacity of the tidal flat 2 will be significantly increased.

The present invention has been made in view of the above circumstances, and when purifying seawater in a semi-enclosed sea area, the amount of seawater exchange can be increased as compared with a conventional tidal flat, and the purification capacity is significantly increased. It is an object of the present invention to provide a seawater purification structure capable of efficiently and inexpensively purifying the quality of seawater by utilizing a tidal level difference caused by tide which is natural energy.

[Means for Solving the Problems] In order to solve the above problems, the present invention employs the following seawater purification structure. That is, a seawater purification structure that is provided in a tidal flat in a semi-enclosed sea area and that purifies the quality of the seawater by transmitting the seawater in the semi-enclosed sea area through the tidal flat, wherein the position of the bottom of the tidal flat is A pond that is below the middle water level in the intertidal zone is provided, and a permeable introduction channel is provided in the tidal flat to allow seawater to enter the inside of the pond from the sea area around the tidal flat, and a ceiling is provided in the surrounding sea area side of the headrace channel. It is characterized by providing a submergence at an end position at a middle water level or higher in an intertidal zone, and providing a plurality of water distribution channels extending from the pond to the surrounding sea area in the tidal flat to allow seawater to pass through the tidal flat. And

[Operation] The seawater purification structure according to the present invention effectively and efficiently purifies seawater in a semi-enclosed sea area at low cost by effectively using a tidal level difference due to tide which is natural energy. That is, in the seawater purification structure, when the sea level of the surrounding sea area rises from a low water level (low tide level) to a high water level (high tide level), the sea surface of the surrounding sea area and the pond of the seawater purification structure are not used. There is a difference in water level with the water surface. The seawater in the surrounding sea area having a high water level enters the headrace channel over the submerged dike of the seawater purification structure and is stored in the pond. In this way, when the surrounding sea area becomes a high water level, the water level of the pond also rises to the same water level slightly later than the surrounding sea area. Since the water level of the seawater stored in the pond is higher than the head of the seawater in the tidal flat, it is discharged through the distribution channel to the entire water level of the tidal flat. At this time, the organic matter and pollutant substances contained in the seawater are decomposed by microorganisms and low-living organisms while passing through the above-mentioned headraces, waterways and tidal flats, and are effectively purified.

Further, when the sea surface of the surrounding sea area descends from a high water level to a low water level, a water level difference occurs between the sea surface of the surrounding sea area and the water surface of the pond. The seawater flows from the pond with high water to the surrounding sea area passing through a plurality of water distribution channels and tidal flats and having a low water level. The seawater stored in the pond is discharged to the entire tidal water level via the distribution channel, and this continues until the water level of the pond approaches the low tide level. At this time, the seawater stored in the pond passes through a plurality of water distribution channels and tidal flats, while microorganisms and benthic organisms remove insoluble and suspended substances, purify the water, and flow out to the surrounding sea area.

Embodiment FIG. 1 and FIG. 2 are views showing an embodiment of the present invention. In the figure, reference numeral 11 denotes a seawater purification structure according to the present invention.

The seawater purification structure 11 is provided in the tidal flat 13 of the semi-enclosed sea area 12, and is located in the intertidal zone of the semi-enclosed sea area 12, and aims at purifying the quality of seawater in the semi-enclosed sea area 12. Things. Here, the semi-enclosed sea area 12 is a bay or a bay where a part of seawater is constantly exchanged with seawater of the open sea due to a tidal level difference due to tide. Also, the tidal flat 13 is formed naturally in the semi-enclosed sea area 12 or artificially using a forming material such as clay, silt, sand, etc. so that the whole is not flooded even at high tide. Things.

The seawater purification structure 11 is composed of a pond 21, a headrace 22, a submergence 23, and a plurality of water distribution paths 24, 24,.

The pond 21 is for storing seawater that has entered from the semi-enclosed sea area 12, and is constructed in the central part of the tidal flat 13, and its bottom position is lower than the middle water level in the intertidal zone. The position of the bottom surface of the pond 21 is desirably at or above the low tide level. Here, the water level of the seawater stored in the pond 21 is substantially equal to the water level of the semi-enclosed sea area 12. A headrace 22 is connected to one end around the pond 21.

The headrace 22 is filled with crushed stones 31 and the like, and is used to easily transmit seawater from the surrounding sea area 25 of the tidal flat 13 into the pond 21. The headrace channel 22 is entirely buried in the tidal flat 13 and extends in the horizontal direction. The headrace channel 22 is constructed so that its position is equal to or higher than the middle water level near the intertidal zone. One end 22a of the water conduit 22 is connected to the pond 21, and a submerged bank 23 is attached to the other end 22b.

The submerged levee 23 is formed to have a trapezoidal cross section and a top end that is equal to or higher than the middle water level in the intertidal zone of the semi-closed sea area 12, and is fixed to the sea floor.

The water distribution channel 24 is filled with gravel 32 and the like, and is used to easily transmit seawater from the pond 21 to the surrounding sea area 25. These distribution channels 24, 24, ... are arranged radially from the pond 21 to the surrounding sea area 25, and the individual distribution channels 24 are entirely buried in the tidal flat 13 and extend from the pond 21 to the surrounding sea area 25. It extends like a tree so that it descends slightly, and is constructed so that its position is below the middle water level of the intertidal zone.

The operation and the like of the seawater purification structure 11 configured as described above will be described.

When the sea level in the surrounding sea area 25 rises from low water level (low tide) LWL to high water level (high tide) HWL, the surrounding sea area 25
A difference in water level occurs between the sea surface of the lake and the water surface of the pond 21, and the seawater enters the pond 21 having a low water level from the surrounding sea area 25 over the top of the submerged bank 23 and is stored. At this time, seawater is purified by microorganisms adhering to the surface of the crushed stones 31 and the like and benthic organisms living in the gaps therebetween. In this way, the surrounding sea area 25 has a high water level
When the water level becomes HWL, the water level of the pond 21 also rises to almost the same water level. Since the surface of the seawater stored in this pond 21 is higher than the head of the seawater in the tideland 13,
Released to all 13 water levels. At this time, the seawater is purified by microorganisms adhering to the surface of clay, silt, sand, or the like constituting the gravel 32 or the like, the tidal flat 13, and the benthic organisms living in these gaps.

Also, when the sea surface of the surrounding sea area 25 descends from the high water level HWL to the low water level LWL, a water level difference occurs between the water surface of the surrounding sea area 25 and the water surface of the pond 21, and the potential energy due to the water level difference causes Pond 21 with high water level to surrounding sea area 25 with low water level
There is a flow of water towards Therefore, the seawater stored in the pond 21 permeates into the tidal flat 13 via the water distribution channel 24 and flows out to the surrounding sea area 25. In this way, when the surrounding sea area 25 becomes the low water level LWL, the water level of the pond 21 also falls to the same water level, a void is created in the water distribution channel 24, and oxygen necessary for the purification action of microorganisms and benthic organisms is reduced. Supply will take place. At this time, the seawater is purified by microorganisms adhering to the surface of the gravel 32 and the like, clay, silt, sand, etc. composing the tidal flat 13 and benthic organisms living in these gaps.

As described in detail above, in the seawater purification structure 11, the tidal flat 13 is provided with the pond 21 whose bottom position is equal to or lower than the middle water level of the intertidal zone, and inside the tidal flat 13 from the sea area 25 around the tidal flat 13. A permeable headrace 22 is provided inside the pond 21 to allow seawater to penetrate, and a submergence 23 is provided on the side of the seawater 25 near the headrace 22 with a top end at a middle water level or higher in the intertidal zone. Since a plurality of water distribution channels 24 extending in a tree shape from the other 21 to the surrounding sea area 25 are provided inside in order to allow seawater to permeate through the tidal flat 13, the following excellent effects can be obtained.

(B) The permeability of the introduction channel 22 and the distribution channel 24 is about 1000 to 10,000 times greater than that of the tidal flat 13, and the pressure loss of the headrace channel 22 and the distribution channel 24 is significantly smaller than that of the tidal flat 13.
The entire 13 area can be an aerobic effective purification area. Therefore, the amount of seawater exchange in the tidal flat 13 can be increased, and the purification ability of the tidal flat 13 can be significantly increased.

(B) By using the tidal force, which is the natural energy of the surrounding sea area 25, it is possible to purify seawater efficiently and at low cost.

(C) Microorganisms adhere to the surface of clay, silt, sand, etc. composing crushed stones 31, gravel 32, etc. and tidal flat 13 in a film-like manner, and these gaps are inhabited by benthic organisms. In addition, organic substances and pollutants contained in seawater are decomposed by microorganisms while passing between them, and are effectively purified, thereby enabling high-grade purification of seawater. In addition, suspended substances and grown microorganisms are eaten by the action of benthic organisms, and clogging is reduced.

(D) By providing the submerged levee 23, the seawater in the pond 21 does not flow backward from the headrace channel 22 to the surrounding sea area 25 even if the headrace channel 22 has a cross section near the low tide level. Thus, the number of water conduits 22 that contribute to purification increases.

(E) It is possible to secure a safe water area close to water in the tidal flat 13, enhance the surrounding scenery, and make suitable recreation facilities.

In the above-described embodiment, the seawater purification structure 11 is provided in the tidal flat 13, but this configuration may be any configuration that can purify the seawater in the semi-enclosed sea area 12,
For example, even when the seawater purification structure 11 is provided on a beach or the like, the purification efficiency of the beach can be significantly increased in the same manner as described above.

[Effects of the Invention] As described above in detail, according to the present invention, the quality of this seawater is provided in a tidal flat in a semi-enclosed sea area, and the seawater in the semi-enclosed sea area is transmitted through the tidal flat. A seawater purification structure for purifying, wherein a pond whose bottom is located at a middle water level or lower in an intertidal zone is provided in the tidal flat, and a permeable portion for allowing seawater to enter the pond from the sea area around the tidal flat into the tidal flat. Provision of a water introduction channel, a submerged levee at the top of the headwater on the side of the surrounding sea area of the headrace above the middle water level of the intertidal zone,
Since the tidal flat is provided with a plurality of water distribution channels extending from the pond to the surrounding sea area in order to allow seawater to pass through the tidal flat, the following excellent effects can be obtained.

(A) The permeability of the headrace and the distribution channel is much larger than that of the tidal flat, the pressure loss of the headrace and the distribution channel is significantly smaller than that of the tidal flat, and the entire tidal flat can be an effective purification area. . Therefore, the amount of seawater exchange in the tidal flat can be increased, and the purification capacity of the tidal flat can be significantly increased.

(B) It is possible to purify seawater efficiently and at low cost by using the tidal force, which is natural energy in the surrounding sea area.

(C) Crushed stones, gravel, etc., clay, silt,
Microorganisms adhere to the surface of sand etc. in the form of a film.Between these gaps, benthic organisms inhabit.Because organic matter and pollutants contained in seawater permeate between them, The water is trapped and decomposed, is effectively purified, and enables high-grade seawater purification. In addition, suspended substances and grown microorganisms are eaten by the action of benthic organisms, and clogging is reduced.

(D) By providing a submerged dike, seawater in the pond does not flow backward from the headrace channel to the surrounding sea area even if the headrace channel has a cross section near the low tide level. Waterways increase.

(E) It is possible to secure a safe water area close to water in the tidal flat, enhance the surrounding scenery, and make it a suitable recreation facility.

[Brief description of the drawings]

1 and 2 are views showing an embodiment of the present invention. FIG. 1 is a schematic plan view of a seawater purification structure, and FIG. 2 is a cross-sectional view taken along line II-II of FIG. FIG. 3 is an explanatory view for explaining seawater exchange due to ebb and flow of a general tidal flat. 11 ... Seawater purification structure, 12 ... Semi-enclosed sea area, 13 ... Tidal flat, 21 ... Pond, 22 ... Headway, 23 ... Submergence, 24 ... Distribution channel, 25 ... Surrounding sea area, 31 ... crushed stone, 32 ... gravels.

──────────────────────────────────────────────────続 き Continuing on the front page (73) Patent holder 999999999 Sanyo Hydrographic Surveying Co., Ltd. 1-3-17, Nihonbashi-Horidome-cho, Chuo-ku, Tokyo (73) Patent holder 999999999 Takenaka Civil Engineering Co., Ltd. 8-chome, Ginza, Chuo-ku, Tokyo 21-1 (73) Patent holder 999999999 Honma Gumi Co., Ltd. 3300-3, Minomachi, Nishiminato-machi, Niigata, Niigata Prefecture (73) Patent holder 999999999 Mitsui Fudosan Construction Co., Ltd. 3-5-2 Kasumigaseki, Chiyoda-ku, Tokyo (73) Patent holder 999999999 Rinkai Construction Co., Ltd. 2-3-8 Shiba, Minato-ku, Tokyo (72) Inventor Chiaki Niwa 2-16-1 Kyobashi, Chuo-ku, Tokyo Shimizu Corporation (72) Inventor Kiyoshi Nikaido 2-6-9 Maruyama, Kamagaya-shi, Chiba (72) Inventor Shinobu Yamaguchi 1-11-25 Higashioi, Shinagawa-ku, Tokyo Inside Goyo Construction Co., Ltd. (72) Akiya Nishihara Kiyoshi 8-21-1, Ginza, Chuo-ku, Tokyo (72) Inventor Kazuhide Furukawa 2-3-8 Shiba, Minato-ku, Tokyo Rinkai Construction Co., Ltd. (58) Field surveyed ( Int.Cl. ⁶ , DB name) C02F 3/00 E02B 3/00 C02F 3/06

Claims (1)

(57) [Claims] 1. A seawater purification structure provided on a tidal flat in a semi-enclosed sea area and for purifying the quality of the seawater by permeating the seawater in the semi-enclosed sea area through the tidal flat. Is provided with a pond where the position of the intertidal zone is equal to or lower than the middle water level, a permeable headrace for allowing seawater to enter the inside of the pond from the sea area around the tidal flat to the tidal flat, and the surrounding sea area of the headrace. A submerged levee whose top end is located at a middle water level or higher in the intertidal zone is provided on the side, and a plurality of water distribution channels extending from the pond to the surrounding sea area are provided in the tidal flat to allow seawater to pass through the tidal flat. A seawater purification structure characterized by the following.