JP2001104990A - Apparatus for cleaning lakes and marshes - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for cleaning a closed natural water system such as lakes and marshes, rivers or a basin where water bloom is generated by decomposing the water bloom in the natural water system. SOLUTION: A water cleaning apparatus equipped with a water bloom decomposing tank packed with a carrier on which at least one water bloom predatory micro-animal selected from the group consisting of Monas, an aquatic earthworm and Hirudine a ringed worm is fixed is provided. An apparatus wherein a water bloom dispersing means is further provided to the bloom decomposing tank is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying polluted water bodies, particularly large-scale closed natural water systems such as lakes, marshes, dam lakes and rivers. More specifically, the present invention relates to an apparatus for purifying a polluted water area in which harmful algae such as blue water have been generated.

[0002]

2. Description of the Related Art Water pollution of lakes, ponds, rivers, and the like is a very serious environmental problem affecting a wide range of ecosystems including human habitats. An apparatus utilizing the excellent water purification action of the present invention is useful.

[0003] Typically, such a water purification apparatus pumps up polluted water, physically filters large dust and suspended matter through a screen, and then flows the water into a biological treatment tank. The polluted water area is purified by returning the water to the water area. In the biological treatment tank, bacteria and micro-animals are adhered to the carrier, and the action thereof aerobically decomposes organic substances to lower the BOD value and SS value.

However, since the conventional biological treatment tank has been developed mainly for the purpose of treating wastewater, it cannot effectively decompose algae, which are the main polluting organic matter, in polluted water areas such as lakes and ponds. There is a problem.

[0005] The reason why conventional biological treatment tanks cannot efficiently treat algae is that microcystis, a major constituent algae of blue-green algae, which is a major problem in eutrophic waters,
This is because there are many types having a toxic substance such as microxtine (for example, Microcystis viridis), so that they are not easily decomposed and degraded by small animals.

On the other hand, as a method of treating a water system in the natural world, Japanese Patent Application Laid-Open No. Hei 5-237479 effectively describes not only the reduction of BOD, decomposition of ammonia or nitrification but also decomposition of nitrate nitrogen and nitrite nitrogen. Although a method of decomposing is disclosed, this method is not intended for efficient removal of algae.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems in the prior art,
Algae, especially harmful algae such as microcystis, which occur in natural waters, especially in closed natural waters such as eutrophic lakes, ponds, moats, rivers and bays
It is an object to provide a device for purifying the natural water system by efficiently removing water.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is an apparatus for purifying a natural water system by causing a blue-green algae produced in the natural water system to prey and decompose into a blue-green predatory micro-animal. , Monas, aquatic earthworm, and locust beetle, provided with an algae decomposition tank filled with a carrier to which at least one algae predator microanimal is immobilized.

[0009]

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for purifying polluted water in a natural water system by a blue-green predatory microanimal.

[0010] More specifically, according to a microscopic animal group selected from Monas, aquatic earthworm, and rotifer,
Provided is a device for purifying polluted water in a natural water system contaminated with blue water.

The present invention further provides a method for purifying polluted water in a natural water system using the above-mentioned measure.

The apparatus of the present invention purifies polluted water by removing blue water in natural water systems in which natural water has been generated, particularly in closed natural water systems such as lakes, marshes, dam lakes, rivers, ponds, and moats.

When the water system in which the blue water has been generated is used as a water source, it is also possible to reduce the water treatment failure due to the blue water by incorporating the apparatus of the present invention in the preceding stage of the water treatment apparatus. That is, the apparatus of the present invention can also be used as a primary treatment for removing blue water in a water supply source.

Hereinafter, the present invention will be described in detail with reference to examples. However, the following examples are not intended to limit the scope of the present invention in any way.

[Embodiment 1] In this embodiment, a purifying apparatus having a basic configuration provided with a single blue-green algae decomposition tank is disclosed. Hereinafter, the apparatus of this embodiment will be described with reference to FIG.

The apparatus of this embodiment includes an intake pipe 1 for removing polluted water from a natural water system to be purified, a water dispersal means 2 to which the water intake pipe 1 is connected, and a downstream stage of the water dispersal means 2. A water digestion tank 3 that is connected and filled with a carrier 4 to which a water predation micro-animal is immobilized, a stirring means 5 for stirring the carrier 4, and dispersing the carrier and polluted water in the water bloom decomposition tank 3. Diffuser plate 6 and air pump 7,
The sedimentation tank 8 includes a sedimentation tank 8 connected to a stage subsequent to the blue water decomposition tank 3, and a return pipe 9 for returning purified water from the sedimentation tank 8 to the natural water system.

The polluted water to be purified by the apparatus of the present embodiment is a polluted water derived from a natural water system in which blue-green algae is generated, in particular, a closed natural water system such as lakes, marshes, dam lakes, rivers, ponds, moats and the like. Water is first sent to the blue-green algae dispersion means 2 through a water intake pipe 1.

The blue-green algae dispersing means 2 is provided with the above-mentioned pollutant so as to be able to prey and decompose the blue-green algae when only Monas is fixed as a blue-green predator in a blue-green decomposition tank 3 installed at the latter stage of the means. This is a means for dispersing blue-green algae in water to single cells. Since Monas cannot prey and decompose the colony-shaped water bloom, when only Monas is used as the water bloom prey micro-animal, it is necessary to disperse the water bloom to single cells by the water bloom dispersion means 2. The dispersing is preferably performed completely so that 100% of the blue-green algae are dispersed in a single cell.

Means for dispersing the blue-green algae include, but are not limited to, ultrasonic irradiation, shearing force due to flow, pressure fluctuation when passing through an orifice or Venturi tube, and cavitation.

The dispersion strength of the blue-green algae dispersing means 2 is required to disperse the blue-green algae to single cells as described above, but it must be set so that the blue-green algae cells themselves are not crushed. It will be obvious to those skilled in the art that it is easy to select an appropriate strength by appropriately changing the conditions.

The polluted water containing blue-green algae dispersed by the blue-green algae dispersion means 2 is sent to a blue-green algae decomposition tank 3 through a water pipe. Since the blue-green algae decomposition tank 3 is filled with the carrier 4 on which the blue-green predator micro-animals are fixed, the blue-green algae contained in the polluted water sent to the decomposition tank are predated by the blue-green algae predator. Decomposed.

The blue-green predator micro-animal is selected from at least one of the group consisting of Monas, aquatic earthworm, and rotifer. As shown in the following examples, if Monas coexists with aquatic earthworms or rotifers, the growth of Monas is strongly inhibited, and aquatic earthworms and rotifers also suppress the growth of each other. It is preferable not to allow these blue-green predator micro-animals to coexist.

The size, shape and material of the blue-green decomposition tank 3 may be arbitrarily selected according to the amount of contaminated water to be treated.

The carrier 4 has a pore size of about several tens to several hundreds μm,
It is preferable to use a porous carrier having a size of about several mm to 1 cm. As the porous carrier, porous cellulose or the like can be used, but is not limited thereto.

In order to immobilize the blue-green predator microanimal on the carrier 4, any technique known to those skilled in the art and including a carrier binding method and an entrapment method can be used.

The carrier 4 is preferably a fluidized bed type in which the carrier 4 is dispersed and filled in the blue-green algae dispersion tank 3 so as to efficiently decompose the blue-green algae, but may be a fixed bed type.

The shape of the carrier 4 can be any shape such as a sphere, a plate, or a string. In the case of a fixed bed type, if a string-shaped carrier is used, the micro-animals that prey on blue-green algae colonize at high density. Will do.

In the apparatus of the present embodiment, a stirring means 5 is attached to the water-bloom dispersion tank 3 in order to uniformly disperse the carrier 4 and increase the efficiency of fixing of the blue-green predator micro-animals on the carrier. It is preferable that the stirring means 5 is slowly rotated at about 1 rpm, and the shape and the installation site can be arbitrarily selected. Therefore, the shape of the stirring means 5 is not limited to the water wheel type shown in FIG. 1, but includes a rod shape and a plate shape.

Furthermore, the apparatus of this embodiment is provided with a diffuser plate 6 and an air pump 7, which cause the carrier to flow at a relatively high speed of about 5 cm / sec or more, thereby predator of the predator of the blue-green predator. (In the case of Monas, aquatic earthworms, etc.) are not settled.

A sedimentation tank 8 is connected to the downstream of the blue-green decomposition tank 3. In the sedimentation tank 8, the residue of the blue-green predator micro-animals and the blue-green algae suspended from the carrier is removed, and the water is completely removed. Be purified.

The purified water is returned to the natural water system through the return pipe 9.

By repeating this circulation, purification of the natural water system is achieved by decomposing and removing the water bloom in the natural water system and suppressing the proliferation.

[Embodiment 2] In this embodiment, a purifying apparatus having a plurality of water-bloom decomposition tanks is disclosed. Hereinafter, the apparatus of this embodiment will be described with reference to FIG.

The structure of the apparatus of this embodiment is basically the same as that of the apparatus of the first embodiment, except that a plurality of water digestion tanks are provided.

The apparatus is connected to a water intake pipe 1 for taking in polluted water from a natural water system to be purified, a water dispersal means 2 to which the water intake pipe 1 is connected, and a downstream part of the water dispersal means 2, A primary blue-green algae decomposition tank 3 filled with a carrier 4 on which monas is fixed, and a carrier 5 on which aquatic earthworms are fixed
, A diffuser plate 7 placed at the bottom of the first blue-green decomposition plant 3 and the second blue-green decomposition plant 6, and the diffuser plate 7, An air pump 8 for supplying air to both the blue-green decomposition tanks, a stirring means 9 for stirring the carrier 5, a sedimentation tank 10 connected to the second stage of the second green-water decomposition tank 6, And a return pipe 11 for returning purified water to the water system.

The primary water-bloom decomposition tank 3 is filled with a carrier on which monas is fixed, which can prey and degrade the single-cell water bloom very effectively. The blue-green algae is decomposed and removed in the first blue-green algae decomposition tank 3.

On the other hand, an aquatic earthworm capable of predating a colony of blue-green algae in which several or more cells are aggregated is fixed in the secondary blue-green decomposition tank 6, so that the blue-green algae that did not become a single-cell state was decomposed. Decomposed and removed in the tank. In addition to the aquatic earthworms, the second blue-green algae decomposition tank 6 may be filled with a carrier on which the rotifer is fixed, more preferably, instead of the aquatic earthworms.

The operation and conditions of other components are described in Example 1.
As described in the above.

[Example 3] In this example, it was demonstrated that the efficiency of predation and decomposition by Monas is improved by dispersing a group of blue-green algae.

FIG. 3 shows an experimental system used in this embodiment.

First, water in which colony-shaped algae 1 (initial concentration: 5.0 × 10 ⁶ N / mL ⁻¹ ) collected from a natural lake is suspended is passed through a diaphragm pump 2 (pump capacity: 200 L / hour), and the diaphragm pump is By the pressure fluctuation of 2, the colony was broken into blue-green algae and dispersed to single cells. Then, Monas 4 (4.5 × 10 ³ N / m 2) was added to the suspension water containing the dispersed Aoko 3.
L- ¹ ) was tested. As a control, diaphragm pump 2
A suspension water containing colony-shaped blue-green algae 1 that had not passed through was used for Monas.

Subsequently, a rotary shaking culture device (50 rpm)
, Predation decomposition experiments were performed in a batch mode at 25 ° C in a dark place, and the predation decomposition rates for each were quantified.

FIGS. 4 and 5 show the results.

FIG. 4 shows the time-dependent changes in the cell numbers of the dispersed blue-green algae (black circles) and the untreated colony-shaped blue-green algae (white circles). As is clear from the figure, the number of cells in the dispersed blue-green algae was significantly reduced after 24 hours as compared with the untreated colony-shaped blue-green algae.

FIG. 5 shows a comparison of the change over time in the number of Monas individuals in each suspension water containing the water-treated blue-green algae (black circles) and the untreated colony-shaped blue-green algae (white circles).

Monas, a predator of blue-green algae, showed more than twice the growth rate in the water-suspended water containing the dispersed blue-green algae, as compared to the suspension water containing the untreated colonies.

From FIGS. 4 and 5, it was shown that the dispersion of blue-green algae has an effect of improving the predation and decomposition rate of Monas.

[Embodiment 4] In this embodiment, a purifying apparatus (FIG. 6) in which an ultrasonic dispersing apparatus is attached in front of a rotary stirring type fluidized bed blue-green decomposition tank filled with a porous carrier to which monas is attached is used. Used to demonstrate that the growth of dispersed blue-green algae is more efficiently suppressed by Monas than when not dispersed.

Hereinafter, the configuration and experimental conditions of the purifying apparatus used in this embodiment will be described in detail with reference to FIG.

The model lake 1 is a large freshwater microcosm having a capacity of 500 L (owned by the National Institute for Environmental Studies), in which a colony-shaped water bloom 2 is cultured. The model lake 1 is irradiated with light from the artificial sun 3 at a light-dark cycle of 12 hours so that the illuminance of the water surface averages 20,000 Lux so that the colony-shaped water lily 2 can grow.

The polluted water containing the water-bloomed watermelon 2 is sent to the dispersing device 5 by the pump 4. Since the ultrasonic vibrator 6 is attached to the dispersing device, the colony-shaped blue cocoon 2 is dispersed to a single cell state by the action of the ultrasonic vibrator. The ultrasonic vibrator 6 was set at an intensity (output: 20 W, frequency: 28 KHz) at which the water-bloom cells themselves were not crushed, and operated for 4 minutes. Under these conditions, a dispersing rate of almost 100% was achieved.

The suspended water containing the dispersed blue-green algae is passed through a liquid feed pipe 7 to a fluidized-bed blue-green algae decomposition tank 8 (effective volume: 6 L, hydraulic retention time: 4 hours) provided with rotary stirring blades. Sent. In the watermelon decomposition tank 8, a porous cellulose carrier 9 immobilized with Monas, a predator of watermelon, is contained.
(300 μm, 5 mm square, no surface treatment) is filled by about 40%, so that the dispersed blue-green algae is decomposed and decomposed in the blue-green algae decomposition tank 8. The water purified by the blue water decomposition tank 8 is returned to the model lake 1 by the pump 10.

FIG. 7 shows the water-bloom removing capability of the purification device when the dispersion of water-bloom (microcystis) by ultrasonic waves was not performed. The chlorophyll a concentration, which is proportional to the number of blue water cells, was used as an index of the number of blue water cells.

The water purifying ability of the purifying apparatus is different between a model lake and marsh system to which a water digestion tank is connected (hereinafter referred to as a water decomposition tank connection system) and a model lake and marsh system which is not connected to a water bloom decomposition tank (hereinafter to be referred to as a control system). Was evaluated by comparison.

Since two types of water-bloom used in the present experiment were present: a single-cell dispersed form and a form forming a colony, the dispersed blue-green algae were first decomposed and degraded by Monas in a blue-green algae decomposition tank. From 10 days to 14 days, the amount of chlorophyll-a in the system connected to the water digestion tank decreased significantly compared to the control system. However, the amount of chlorophyll-a started to increase after 14 days in the system connected to the water digestion tank.

FIG. 8 shows a state in which a pre-decomposition treatment of monas in a blue-green algae decomposition tank is performed by performing a dispersion treatment of a blue-green algae by a supersonic wave in a preceding stage of a blue-green algae decomposition tank. 3) shows the change with time of the chlorophyll a concentration in FIG.

As shown in FIG. 8, the concentration of chlorophyll a in the system connected to the dispersing treated blue-green algae decomposition tank increased almost in a similar manner until the sixth day from the start of the experiment, but from day 6 onward. Chlorophyll a in the system connected to the decomposing tank
The rate of increase in concentration was significantly slower than in the control system.
Further, on the 22nd day from the start of the experiment, the concentration of chlorophyll-a in the system connected to the decomposition-treated blue-green algae decomposition tank was less than half that of the control system. From day 22 onwards, the chlorophyll-a concentration in the system connected to the dispersing treated blue-green algae decomposition tank began to decrease, and on day 31 from the start of the experiment, the chlorophyll-a concentration decreased to 10% or less of the control system.

As described above, the present example showed that by performing the dispersing treatment in the preceding stage of the water-bloom decomposition tank, the growth of water-bloom could be effectively suppressed.

[Example 5] In this example, Monas, aquatic earthworm (A. hemprichi), and P. erythropht
In order to establish a more effective method for degrading blue-green algae using a mixed culture system of C. halma), the interaction between microanimals was quantitatively examined.

In this example, the test was performed under the conditions of 20 ° C., a dark place, standing, and a batch system. A mixed culture system in which 50 mL of M11 medium was added to a 100 mL Erlenmeyer flask (dry heat sterilization, 151 ° C., 90 minutes) and Monas, aquatic earthworm, and convolvulus were inoculated, and a control system in which only one of each was inoculated Used as Further, in this example, the inoculation concentrations of algae and micro-animals were adjusted so that the number of individuals was similar to the environment in the blue-green algae decomposition tank. Food was replenished with dispersed Microcystis viridis to compensate for predation losses.

After a certain period of time, the number of microanimals in each culture system was counted, and the interaction of microanimals was quantified from the interaction influence value Im. Table 1 shows the Im values.

[0062]

[Table 1]

Im = Nc / Ne where Im is the interaction value between microanimals, Nc is the number of microanimal individuals serving as a control system in each row at each elapsed time in the experiment, and Ne is
Indicates the number of individuals in each row at each experimental elapsed time when the microanimals shown in each row are cultured with the microanimals listed in each column.

That is, when the Im value is close to 1, it indicates that there is almost no influence from other small animals. Also,
When the Im value is less than 1, the effect is inhibited by other micro-animals, and when the Im value is more than 1, the proliferation is activated by the other micro-animal.

When Monas was cultured in a mixed culture with the rotifer or the aquatic earthworm, the Im values were 0.67 and 0.24, respectively, indicating that Monas was inhibited by the rotifer and the aquatic earthworm. Monas suffers strong growth inhibition, especially from aquatic earthworms. Conversely, aquatic earthworms exhibit a high Im value of 2.21 when Monas coexists, and their growth is activated by Monas. Therefore, it is presumed that aquatic earthworms prey on Monas.
In addition, it was found that aquatic earthworms mutually exert inhibitory effects in the presence of the rotifer.

From the above results, when Monas and aquatic earthworm are not coexisted, the number of Monas is increased, and the predation / decomposition rate of the dispersed Microcystis is increased.
It is judged that the absence of the aquatic earthworm and the rotifer also causes less mutual inhibition and increases the predatory decomposition efficiency.

[0067]

According to the present invention, water-bloom can be decomposed and removed, which is difficult with a conventional water purification apparatus for wastewater treatment.

Therefore, according to the present invention, it is possible to decompose and remove the blue-green algae in the natural water system in which the blue-green algae bred due to eutrophication, especially large-scale closed natural water systems such as lakes, marshes, dam lakes, and rivers. As a result, the BOD value, COD value, and SS value of such a natural water system decrease.

In particular, an apparatus provided with a plurality of algae decomposition tanks in which various kinds of algae predatory micro-animals are individually immobilized and an algae dispersion means can have extremely high algae resolution.

[Brief description of the drawings]

FIG. 1 is a diagram showing a water purification device according to a first embodiment.

FIG. 2 is a diagram showing a water purification device according to a second embodiment.

FIG. 3 is a schematic diagram showing an experimental system used in Example 3.

FIG. 4 is a diagram showing that the decomposition rate of blue-green algae is increased by the blue-green algae dispersion process.

FIG. 5 is a diagram showing that the number of Monas, a predator of blue-green algae, increases by the blue-green algae decentralization process.

FIG. 6 is a diagram showing an experimental system referred to in Example 3.

FIG. 7 is a graph showing a change with time in the number of water-bloom cells when no dispersion treatment was performed.

FIG. 8 is a diagram showing a change with time in the number of water-bloom cells when a dispersion treatment is performed.

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Claims (4)

[Claims] 1. A device for purifying a natural water system by predating and decomposing blue water blooms generated in the natural water system to a blue-green predatory micro-animal, comprising at least one selected from the group consisting of Monas, aquatic earthworm, and rotifer An apparatus characterized by comprising a blue-green algae decomposition tank filled with a carrier on which one blue-green predator micro-animal is immobilized. 2. The apparatus according to claim 1, wherein said water-eating micro-animal selected from the group consisting of Monas, aquatic earthworm, and rotifer is not coexistent. 3. The apparatus according to claim 1, wherein a water-bloom dispersing means is provided in a stage preceding the water-blowing decomposition tank. 4. A method for purifying a natural water system in which blue-green algae has been generated, using the apparatus according to claim 1.