JPH03249997A - Water cleaning device for eutrophicated lake and pond - Google Patents

Abstract

PURPOSE:To clean an eutrophicated lake or pond at a low running cost by embedding suction pipes bored with plural holes on the peripheral surfaces into the bottom land of the lake or pond and connecting a drain pipe opened toward the front layer of the like or pond interposed with a drain pump to the suction pipe. CONSTITUTION:Plural pieces of the suction pipes 2 bored with the plural holes on the circumference are flatly embedded into the bottom land of the eutrophicated lake or pond 1. The drain pipe 3d interposed with the drain pump 30 for lifting the underground water and bored toward the front layer of the lake or pond 1 is connected to the suction pipes 2. Namely, the underground water in the suction pipes 2 is lifted and is discharged toward the surface layer of the lake or pond, by which the eutrophicated lake or pond is cleaned. The driving power of the drain pump relating to this lifting is necessitated merely to accelerate the draining and, therefore, the running cost is reduced. The eutrophicated water is utilized and there is no need for a denitrification tank under the lake bottom. There is no need for the procurement of land and the construction cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a water purification device for eutrophic lakes and marshes where phytoplankton and the like have grown.

(Conventional technology) Speaking of water pollution, we can think of ordinary organic pollution.
Measures are taken to remove phosphorus or nitrogen through aeration to improve the oxygen-deficient condition in the water.

In recent years, the eutrophication of lakes and marshes has progressed, and the number of lakes and marshes polluted by the occurrence of phytoplankton, so-called algae, has increased noticeably. The surface area of this lake is large (in the surface layer, phytoplankton actively breeds, releasing oxygen into the water and absorbing carbon dioxide gas in the water, so the oxygen concentration and alkalinity are kept sufficiently high. There is.

Therefore, in order to purify this lake, it is not effective to simply aerate the organic matter in the lake; first, under aerobic conditions, the organic matter is decomposed to some extent, and the ammonia produced is converted into nitrite. Two water treatment processes are required: a secondary treatment and a tertiary treatment, as it requires an oxidation process to convert it to nitric acid, and a process to separate nitrite and nitric acid by allowing bacteria to respire nitrate under anaerobic conditions. It had been.

(Problem to be solved by the invention) However, if conventional technology is used to purify the water quality of eutrophic lakes and marshes, a concentrated air tank is first required, and denitrification is anaerobic. Since denitrification is carried out under specific conditions, a large denitrification tank is required, which poses problems such as securing land and construction costs, and it takes time and money to install it in a lake.

In addition, if conventional technology using activated sludge or the like is used as another means, the organic matter will be reduced too much in the process, so the organic matter for denitrification in the tertiary treatment is replaced by artificial additives such as methanol. I had to rely completely on it.

Therefore, the so-called sorbable nitrogen that can be absorbed by phytoplankton that has grown in eutrophic lakes is limited to ammonia, nitrite, and nitric acid. It has been desired to develop a device that can prevent abnormal growth of phytoplankton by converting nitric acid into nitric acid and removing it.

The present invention aims to provide a water purification device for eutrophic lakes and marshes that takes advantage of the purification ability of the natural world.

(Means for Solving the Problems) In order to achieve the above object, the present invention has a plurality of water suction pipes each having a plurality of holes in the circumferential surface buried in the ground at the bottom of a eutrophic lake. The water suction pipe is characterized in that a drainage pump for pumping up groundwater is interposed in the water suction pipe, and a drainage pipe opening toward the surface layer of the lake is connected to the water suction pipe.

In addition to the above configuration, underground above the water intake pipe,
A plurality of solution dispersion pipes with a plurality of holes in the circumferential surface are buried in a planar manner, and a liquid sending pipe having a pressurizing means is connected to the solution dispersion pipes in order to permeate organic substances such as methanol into the ground. It is characterized by what it did.

(Function) Since the present invention is configured as described above, lakes and marshes in a eutrophic state can be used and purified as described below. First, phytoplankton actively proliferates in the surface layer of lakes, releasing oxygen and absorbing carbon dioxide.
The oxygen concentration and alkalinity are sufficiently high to promote the decomposition of organic matter and the nitrite or nitrification of ammonium salts without artificial manipulation. In addition, the water that percolates from the bottom of lakes and marshes and becomes groundwater contains nitrite and nitric acid as well as organic matter that exists in the ground. Under the nitrate respiration of denitrifying bacteria, the oxygen in nitrous acid and limestone acid is used to decompose organic matter and release nitrogen gas. The groundwater pumped up by the NF water pump is then discharged to the surface layer of the lake through a drainage pipe.
Nitrogen, which supports the reproduction of phytoplankton, is reduced overall, suppressing the proliferation of phytoplankton, and reducing organic matter in the lake water, making it cleaner.

In addition, when lakes and marshes are under more aerobic conditions from middle to lower layers, nitrite and nitrate nitrogen I should be removed.
On the other hand, organic matter decomposes and becomes insufficient, so organic matter for denitrification can be replenished by replenishing organic matter such as methanol into the ground using a solution dispersion pipe.

(Example) Next, an example of the present invention will be described based on FIGS. 1 and 2. As shown in the figure, a lake 1 is excavated, its bottom surface is compacted to make it impermeable, and a plurality of water suction pipes 2 are installed in parallel in a plane on the soil. This water suction pipe 2
The diameter of the pipe is large and the length is short, and small diameter holes are uniformly bored around the circumference so that water does not seep through. Further, the circulation device 3 installed upright on the bottom of the lake 1 includes a water collection pipe 3a, a water suction tank 3b, a drainage pump 3C, and a drainage pipe 3d, and a plurality of water suction pipes 2 are connected to the water collection pipe 3a. The upper end of the water absorption tank 3b protrudes above the water, and a drainage pump 3c is provided inside, and a water collection pipe 3a and a drainage pipe t3d are connected thereto. The drain pipe 3d extends above the water absorption tank 3b and is open toward the surface layer of the lake 1. Normally, this opening is gradually enlarged and opened into the water in order to save the head of the drainage pump 3C and reduce its operating costs. Sometimes it is opened. Further, the amount of water discharged by the drainage pump 3c is determined to be an amount that can denitrify the nitric acid and nitrous acid produced in the lake 1 that has been drained.

Further, at the bottom of the lake, surrounding the water absorption tank 3b, a coarse filter layer 4a, a medium filter layer 4b, and a fine filter layer 4c made of gravel and sand are stacked in order from the bottom of the bottom to form a filter layer 4. has been done. The water suction pipe 2 and the water collection pipe 3a are located in the lowermost coarse filter layer a. Furthermore, a denitrification layer 5 made of soil having appropriate water permeability is filled above the fine filter layer 4C. Above the denitrification layer 5 is a coarse-grained diffusion layer 6a and a fine-grained diffusion layer 6b.
covered with a solution diffusion layer 6 consisting of a coarse particle diffusion layer 6
A plurality of solution dispersion pipes 7 are buried in parallel in a plane. The solution distribution tube 7 has a large diameter and a short length to prevent uneven distribution of the solution, and small diameter holes are uniformly bored on the circumference, and the solution distribution tube 7 has a large diameter and a short length to prevent uneven distribution of the solution. It is connected to a liquid feeding pipe 8a of a liquid feeding device 8 consisting of a tank 8c. Further, the upper part of the solution diffusion layer 6 is covered with a coating layer 9 having appropriate water permeability.

Therefore, it goes without saying that the water permeability of the coarse particle filter layer 4a surrounding the water suction pipe 2 and the coarse particle diffusion layer 6a surrounding the solution dispersion pipe 7 is made sufficiently high. In addition.

Normally, the water is drained in this way and the bottom of the lake 1 is excavated to install the water suction pipe 2, but if it is difficult to drain the water, there are enforcement methods described below.

Next, the water permeability of the denitrification layer 5 and the coating layer 9 will be explained.

It is possible to use excavated soil for these soils, but if the permeability is too low, the load on the drainage pump 3C will increase, making it unsuitable, so mix gravel, sand, etc. to increase water permeability. It is desirable to improve the

Regarding the thickness of the coating layer 9, if it is too thick, substances in the coating layer 9 will be consumed before methanol etc. is supplied and denitrification will be inhibited, so it is necessary to make it as thin as possible. If there is a risk that the fine-grain diffusion layer 6b will be exposed due to excavation, cobbles or the like are mixed in to strengthen the resistance against scour.

Regarding the thickness of the denitrification layer 5, if it is increased, the head of the drainage pump 3c will be increased, and if it is decreased, the head of the water suction pipe 2,
The cost of the solution dispersion pipe 7 and the like is high, and the decision is made solely from an economic standpoint; however, the volumes of the denitrification layer 5 and the coating layer 9 should be determined so as to provide sufficient time for denitrification. Of course.

In addition, methanol, etc. to be flowed into the solution diffusion layer 6 is supplied to the solution distribution pipe 7.
Since the solution is multiplexed so as to be sufficiently diffused in the horizontal direction after leaving the solution, the solution is diluted and stored in the solution tank 8C. Further, the amount of water discharged by the drainage pump 3C is determined so that the water within the castle becomes sufficiently aerobic and the amount of nitrous acid and nitric acid is generated in accordance with the amount of nitrogen to be removed.

Next, nitrification and nitrification of organic matter using eutrophic lake 1 will be explained. In Lake 1, phytoplankton proliferates on the surface layer, and as mentioned above, the oxygen concentration and alkalinity are extremely high (ammonia is produced by the decomposition of organic matter, and nitrite and nitrification of ammonia are progressing. Since it is an absorbable form that can be used by phytoplankton, it is necessary to denitrify it by converting it into nitrite and nitric acid.Therefore, the groundwater that percolates from the lake water is pumped up and discharged to the surface layer of the lake, and the water is circulated to some extent. The temperature difference between the surface layer and the bottom layer is small (the surface layer and the bottom layer are easier to combine), and the organic matter in the water is decomposed underground and becomes less, so the lake water becomes more gaseous and the organic matter decomposes and is generated as a result. Nitrite oxidation and nitrification of ammonia are promoted. On the surface of lakes and marshes, nitrite oxidation and nitrification proceed as shown in the following equations 11) and (2), respectively.

2 NH4”+ 30x -2NOx-+ 2820+
4H4...1ll N Ox-Jusai 02→N Ox -...(2)(1)
In the formula, nitrite oxidation of ammonia is caused by rusting bacteria, Nitrosomonas, Nitrosococcus.
, = Trososvira (N 1trosospira)
, - Trosocyst (N 1troSocyst
is), Nitrogloea (Nitrog-1oea
) etc. are involved. Similarly, in formula (2), Nitrobacter <N 1trobacter) and the like are involved.

Moreover, the reaction shown by formula (3) also occurs.

N H4” + 20 t −N Ox −+ 820
+ 28 ”...(3) Since the nitrite and nitric acid produced in this way have a negative charge, they are not captured by soil particles (they seep underground with water).

Next, we will explain the layer of organic matter production within the castle. As mentioned above, the phytoplankton that proliferate on the surface layer and the animals that prey on them eventually die, settle down, and decompose. As a result, some of these organic substances are taken up by the bacterial cells, but eventually the bacterial cells are also decomposed, resulting in a very large amount of organic substances being dissolved in the water. -For example, in ``Aquatic Ecosystems'' by Kinji Hozuki, p. 78, it is written that ``In Lake Weber, dissolved organic matter accounted for 60% of all organic matter, including living organisms.'' There is. This can be inferred from the well-known fact that within the castle grounds, organic matter is continuously excreted from the body from phytoplankton and animals. There is no doubt that it exists in the water. Therefore, since these large amounts of dissolved organic matter are effectively used for denitrification, it is not necessary to replenish methanol or the like, or even if it is replenished, the amount of I may be small.

Next, the effect of denitrification will be explained. If the above-mentioned dissolved organic matter, nitrous acid, and nitric acid seep into the coating layer together with water, the organic matter will be decomposed while consuming the remaining M elements in the surface layer. It is said that anaerobic conditions exist when the depth is 2 cm or more underground. Therefore, denitrifying bacteria in the ground use the oxygen contained in nitrite and nitric acid for respiration, and nitrite and nitric acid are decomposed into water and nitrogen gas through so-called nitrate respiration. The reaction is shown in the following formulas, and the hydrogen in the formulas is the one possessed by organic substances such as methanol.

2NOx-+108-1Nz +4820+208...
・(4) 2NOx-+6H-IN2 +2H,O+20H-・・
・(5) The bacteria that performs such nitrate respiration are Micrococcus (M
1crococcus), Achromobacter (Ac
hromobacter), Bacillus
) etc. are known.

When the organic matter enters the coating layer 9 as described above, consumption of the organic matter begins immediately, so there is no organic matter in the coating layer 9, and denitrification is not carried out (there is a risk that this will occur, but for this reason, the coating layer 9 should be made as thin as possible). Furthermore, as will be explained later, organic substances such as methanol may be supplied and replenished.

In addition, in the present invention, since organic nitrogen compounds within the castle are used for denitrification, ammonia is generated in the denitrification layer 5, etc., but some of it is discharged into the castle together with groundwater and nitrite is generated. Otherwise, it becomes nitric acid, which is then removed when it percolates again. It should be noted that the number of nitrogen devices to be removed does not increase (it simply means that the organic matter containing nitrogen is effectively used for denitrification).

Next, the provision of organic substances such as methanol will be explained. First, the oxygen concentration in lake water is lower than in alcohol tanks, etc.
Decomposition of organic matter takes a long time. Therefore, a large amount of organic matter is still dissolved in the water. This is used for denitrification underground, so if there is little generation of nitrite and nitric acid to be removed, denitrification can be achieved with just the organic matter in the castle, but if there is a large amount of nitrite and nitric acid generated, Since the decomposition of organic matter is also active, there is a shortage of organic matter required for denitrification. Therefore, it becomes necessary to artificially provide organic substances such as methanol. When supplying methanol etc., the discharge force of the pressure pump 8b is variable, and
Since the discharge amount is set to be constant regardless of changes in the lake surface, organic matter can be supplied without excess or deficiency, and therefore the lake water will not become oxygen-deficient due to excess methanol. . Furthermore, since the dish discharged from the solution dispersion pipe 7 is uniform, and the water permeability of the coarse particle diffusion layer 6a is made high, methanol, etc. is almost uniformly diffused between the pipes, and together with water. It can permeate into the denitrification layer 5 and be subjected to denitrification.

Further, the amount of organic substance provided is expressed by the following formula when methanol is used, for example.

Mg=2.47N, +1.53N, +0.87DO=1
61Mg=methanol concentration N1: Nitric acid concentration J
2 ・Nitrous @ concentration Do: Dissolved oxygen concentration However, it is impossible to provide exactly the required amount of methanol, etc., so it is necessary to provide it with a little margin, but methanol, etc. that is not used for denitrification, Under aerobic conditions, it is decomposed into carbon dioxide using conserved oxygen in the water, and under anaerobic conditions, using oxygen combined with hydrogen in the water's tissues.

In this way, the groundwater seeping from the lake 1 passes through the covering layer 9 and the denitrification layer 5, is sucked into the water suction pipe 2, and is discharged into the lake water via the circulation device 3.

In addition, in the present invention, since dephosphorization is not performed, it is possible that indigo species with nitrogen fixing ability are generated, but since organic matter is reduced and the bottom layer is kept aerobic, it is possible to prevent the formation of indigo species from the bottom layer into the water. The elution of phosphorus is suppressed, the amount of phosphorus in water is reduced, and therefore the occurrence of blue-green algae, which have nitrogen-fixing ability, is also suppressed.

In addition, in the present invention, there is no need to pressurize air into pressurized water like in the case of sewage treatment, and the water is simply circulated, so the water permeability of the denitrification layer 5 and the coating layer 9 can be improved. If it is made higher and its flat area is increased, the drainage pump 3
In addition, since the height difference is used to pressurize methanol, etc. in the liquid sending pipe 8a, the power for pressurizing can be small.

In addition, the temperature of the water in the bottom layer of the lake, which seeps into the ground, does not change much, and since it is denitrified underground, it is hardly affected by temperature, and its capacity is stable with little seasonal fluctuation. Although the thermal and denitrifying effects decrease in the winter, there is no practical problem because the effects of sublithic oxidation and hexagonal oxidation also decrease.

Next, an example of a case where it is difficult to fall into water will be described with reference to FIG. First, regarding the installation of water suction pipe lO,
The bottom of the lake was dredged with a pump boat, sand was poured in, and many tubes were driven vertically to form the well frame, and one drainage pump was installed at the top of each tube.
1 is attached. In this case, water suction pipe 10
A plurality of holes are opened in the lower part of the hole, and the positions of the lower parts are arranged in a plane with respect to each other. This intermediate portion also serves as the water collection pipe 3a shown in the first embodiment. Further, the drainage pump 11 is of a submersible type, and its discharge port is located on the surface layer of the lake. In addition, since water cannot fall, it is difficult to install the solution dispersion pipe 7 over the entire surface directly above it, so the solution dispersion pipe 7 is laid between the water suction pipes 1O and 1O in a grid pattern. It is provided. Furthermore, if the sprayed methanol is immediately absorbed into the water suction pipe 10, the efficiency of methanol will decrease, so the interval between them is made large.

When configured as described above, the nitrification effect is the same as in the first embodiment, so a description thereof will be omitted. Now, to explain methanol involved in denitrification, the hot liquid diffusion layer 6 in which methanol is sprayed has high water permeability and the pressure therein is almost uniform, so that water permeates above it almost uniformly.

However, the seepage below is in the vicinity of the water suction pipe lO,
The amount of permeation decreases toward the outside. Therefore, in the solution diffusion layer 6, a water flow is generated from the periphery toward the water suction pipe 10, so if the solution dispersion pipe 7 is placed in the middle of the water suction pipe IO and the water suction pipe 10 next to it, it will be slightly uneven, but it will be sufficient. This means that it can spread.

As mentioned above, water suction pipes 2 and 1 are created using eutrophic lakes and marshes.
Since it was possible to purify the lake 1 by burying the O and solution dispersion pipe 7 in the lake 1, it was possible to reduce construction costs, which required the installation of an aeration tank and a denitrification tank, which were required in the conventional technology. In addition, there was no need for power to heat the air, resulting in cost savings.

(Effects of the Invention) Since the present invention is configured as described above, it is possible to purify eutrophic lakes and marshes by pumping up the groundwater in the water suction pipe and discharging it to the surface layer of the lake. Since the power of the ttL water pump involved is sufficient to promote it, the operating cost is low. In addition, since denitrification can be carried out under the lakebed using eutrophic water, there is no need for a denitrification tank, there is no need to procure land, and construction costs are reduced. Also, this will not damage the scenery.

In addition, most of the organic matter involved in denitrification is sufficient, but when it is supplied, methanol is sprayed using the i=dispersion pipe, so the purification function is enhanced and the efficiency of the purification action is also good. Further, the power of the pressurizing means for dispersing the metal vines is sufficient to promote it, so the operating cost is reduced.

[Brief explanation of drawings]

1' (7 is a cross-sectional view of a lake in an embodiment of the present invention,
FIG. 2 is a plan view of FIG. 1, and FIG. 3 is a sectional view of a lake or marsh according to another embodiment. l...Nkunuma 2, lO...water suction pipe 3c, 11...drainage pump 3d...drainage pipe 7...n liquid distribution pipe 8a...liquid feeding pipe 8b--pressurization Means (pressure pump) (2 idiots) Procedure sleeve 1, case description 1990 Patent Application No. 46977 2, title of invention water purification device for eutrophic lakes 3, 'Amendment person case' Related Patent Applicant Name: Toyo-Kyogyo Co., Ltd. 4, Agent Address: 6 Ochanomizu Square Building B, 1-1 Kanda Surugadai, Chiyoda-ku, Tokyo (2 others) (2) Column for detailed explanation of the invention in the specification (3) Drawings ? , M Correct Contents (1) Amend the application as shown in the attached sheet. (2) In the fourth line of page 2 of the specification, the phrase ``shirin or'' is amended to read [shirin or'' after that, cyrin or''. (3) On page 2, lines 5 and 6 of the specification, the phrase ``occurrence of phytoplankton so-called ``Blue-green algae J'' was replaced with ``so-called ``
This is corrected as "occurrence of phytoplankton such as blue-green algae". (4) In the first line of page 7 of the specification, the phrase ``in an amount that can accommodate the membrane chamber'' should be amended to ``so that the amount of residual organic matter can be balanced.'' (5) “It is not necessary, but” on page 11, line 20 of the specification.
I corrected it by saying, ``Maybe it's not necessary.'' (6) In the 4th line of page 16 of the specification, the phrase "in," is amended to read, "in,". (7) Figure 1 of the drawings shall be corrected as shown in the attached sheet. that's all

Claims (2)

[Claims] (1) A plurality of water suction pipes with multiple holes on their circumferential surface are buried in the ground at the bottom of a eutrophic lake, and a drainage pump is interposed in the water suction pipes to pump up groundwater. A water purification device for eutrophic lakes and marshes, characterized in that a drainage pipe opening toward the surface layer of the lake is connected. (2) A plurality of solution dispersion pipes with a plurality of holes on the circumferential surface are buried in the ground above the water absorption pipe in a planar manner, and organic substances such as methanol are permeated into the ground through the solution dispersion pipes. 2. The water purification device for eutrophic lakes and marshes according to claim 1, further comprising a liquid sending pipe having a pressurizing means connected thereto.