JP2010264384A - Method for removing water bloom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water bloom treatment system which can efficiently collect water blooms widely floating on the water surface of a lake, a dam lake or the like and send the water blooms to a lower layer to inactivate them, and then decompose the water blooms by aerobic microorganisms in an oxygen-rich water area of the lower layer. <P>SOLUTION: The lower layer water area is made to be an oxygen-rich state beforehand by a high concentration oxygen water supply device or a gas-liquid dissolving device. Water blooms and surface water collected by a water bloom collector installed on the water surface are sent into a water bloom diffuser, provided in the vicinity just above the oxygen-rich water area and connected to the water bloom collector through a pipe, to be discharged in the horizontal direction. At this time, aggregates of the water blooms are broken by temperature difference or hydraulic pressure difference, and their gas vesicles are broken to be inactivated. The inactivated water blooms (carcasses) are precipitated and deposited in the oxygen-rich water area with the passage of time, and decomposed by the aerobic microorganisms actively acting therein. Phosphorus generated by the decomposition is coagulated and precipitated with iron ions and the like, and the nitrogen is removed in an oxygen/reduction atmosphere in the lower layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for activating the activity of aerobic microorganisms in a bottom water area of a lake with a low dissolved oxygen concentration that is unlikely to generate a water flow, and for removing the sea cucumber floating on the surface layer by eutrophication.

  In recent years, in eutrophied lakes and dam lakes, blue-green sea bream grows abnormally from early summer to midsummer, and the surface of water is covered with a green film. The occurrence of blue sea bream damages the landscape, causes bad odor due to spoilage, causes fish to die due to lack of oxygen, and impedes filtration at the water purification plant. In addition, when the water in which the water is generated is chlorinated, another harmful effect is caused such that a precursor of trihalomethane is generated.

  In addition, it is known that there are toxic species such as microkistis among sea cucumbers, which is a particularly serious problem in the dam lake which is the water source of the water supply.

  In addition, when the poor oxygen state progresses due to the occurrence of blue sea cucumber, harmful metals are likely to be eluted from the bottom mud due to the reducing action, resulting in another deterioration of water quality.

  Measures against blue sea bream include sun protection, water temperature control, pH adjustment, maintenance of the water quality environment by aeration, planting of firewood, etc., management of the ecosystem, management of inflow water, and development of sewers. In addition, a method of directly collecting and removing the blue sea bream has been tried.

  For example, Patent Document 1 (Japanese Laid-Open Patent Publication No. Hei 6-182324 “Aqua-Treatment Method for Lakes, Ponds, etc.”) and Patent Document 2 (Japanese Laid-Open Patent Publication No. 2007-98342 “Aquo Collection Device”) include aquatic plants from lakes. A method is disclosed in which surface water is introduced into a recovery device to remove flocculent precipitates.

  Patent Document 3 (Japanese Patent Laid-Open Publication No. 11-70382 “Aoi removal device”) adds a chemical to surface water containing aoko to make it a flock, and attaches it to fine bubbles to float and remove it. A method is disclosed.

  In addition, a countermeasure against water-bloom by forced lake water circulation (air-relation) has been devised. Patent Document 4 (Japanese Patent Laid-Open Publication No. 2006-835 “Water Purification System and Water Flow Generation Stir Mixer”) includes a surface layer containing water-bloom. A method is disclosed that uses a water agitation generator that mixes water and bottom water to improve the deactivation of the sea lions and the poor oxygen state of the bottom. In Patent Document 5 (Japanese Patent Laid-Open No. 2006-181565 “Water Purification System and Water Flow Generation Stir Mixer”), the suction port of the pump is installed at a depth of about 1 meter from the surface of a lake or the like, and the sea cucumber is placed with the surface water. A method is disclosed in which the water is sucked with a pump, discharged to a lower layer with a depth of 10 meters or deeper, and a water pressure differential shock and a water temperature differential shock are applied to the watermelon to inactivate (kill) the watermelon.

  In addition, Patent Document 6 (Japanese Patent Application Laid-Open No. 8-33888 “Aoco Processing Method and Blue Water Processing Device”) and Patent Document 7 (Japanese Patent Application Laid-Open No. 2005-152848 “Aoco Recovery System Using Electrochemical Technique”) include: Japanese Patent Application Laid-Open No. 2005-138029 discloses a method for suppressing algae killing and growing in closed water areas such as lakes and algae killing and growth of blue sea cucumber. For the suppression device "), a method for suppressing or killing the growth of sea cucumber with ozone or ultraviolet treatment is disclosed in Patent Document 9 (Japanese Patent Laid-Open No. 2006-14625," Floating cyanobacteria collection device and floating cyanobacteria processing system "). Have proposed a method of applying pressure to the surface water containing the collected sea cucumber with a pressure pump to destroy gas vesicles of the sea bream and crush the colonies.

  In addition to this, there are known methods for installing various kinds of sea cucumber removal devices on ridges and floats, pumping surface water and sea bream together, filtering the sea bream, and removing it.

  However, in general, since the water surface on which the watermelon is floating is very wide, the watermelon as disclosed in Patent Documents 1 and 2 or Patent Document 3 is collected by flocculation sedimentation, or floated, filtered, etc. However, the method for removing the sea cucumber requires a large-scale processing apparatus, which is problematic both in terms of efficiency and economy, and there are many problems in the disposal of the separated sea cucumber. Therefore, there is a reality that there are no examples of practical use in large lakes and dam lakes.

  Similarly, there is a problem that a considerable number of devices need to be installed in order to collect and process aquatic plants, for example, as disclosed in Patent Document 4, such as the water flow agitation generation method and the lake water upper and lower layer agitation method. It was. Also, many methods for removing sea cucumbers are not suitable for large lakes and dam lakes because of the large influence of strong winds blowing on the surface of the lake and changes in water flow due to heavy rain.

  In addition, as in Patent Document 5, the water is sucked together with the surface water with a pump, discharged into a lower layer with a depth of 10 meters or more, and a water pressure differential shock and a water temperature differential shock are applied to the watermelon to inactivate the watermelon. The activated sea cucumber sinks to the bottom of the lake, but it becomes sludge as it is, and the water quality of the bottom layer is further deteriorated. At this time, metals and phosphorus rich sources such as iron and manganese, which are considered as promoting substances for the growth of blue sea bream, elute from the bottom mud, which causes a problem of promoting the growth of blue sea bream.

  In addition, methods such as shading the surface of the lake with a large fountain device installed on the surface of the lake and dredging mud of the bottom have been implemented, but no significant effect has been achieved.

Japanese Patent Laid-Open No. 06-182324 JP 2007-98342 A Japanese Patent Laid-Open No. 11-70382 Japanese Patent Laid-Open No. 2006-835 JP 2006-181565 A JP-A-8-33888 JP 2005-152848 A JP 2005-138029 A JP 2006-14625 A

  In other words, the problem to be solved is to kill the blue sea cucumber, decompose it in the bottom layer, improve the anoxic state, cut off the breeding cycle of the blue sea bream, and reform the lake.

  The method for removing sea cucumber according to claim 1 is a method for reforming a lake where the bottom layer has become hypoxic and a surface has been swelled, wherein oxygen is dissolved in a high concentration in the water of the lake, The main feature is to continuously supply water to the bottom layer area and maintain the bottom layer area at a predetermined oxygen concentration or more, while taking water on the surface layer together with the sea urchin and discharging it to the bottom layer area at a predetermined flow rate substantially horizontally. To do.

  That is, the invention according to claim 1 inactivates the watermelon by an environmental change such as a change in water pressure or a change in water temperature, and continuously decomposes it by staying in the bottom layer area where aerobic microorganisms are active. Lakes include dam lakes, including rivers and harbors where water is stopped. Moreover, the location of the lake water is not particularly limited here, whether it is the bottom layer or the surface layer.

  In addition, lakes and marshes where water flies occur often have a water surface depth of 1 m or less and a dissolved oxygen concentration of 2 mg / l or less. The predetermined oxygen concentration is 8 mg / l or more, preferably 10 mg / l or more. A high concentration refers to a concentration that maintains this oxygen concentration, for example, 15 mg / l or more. The amount of saturated oxygen dissolved in water at 25 ° C. is 8.11 mg / l. Further, the flow rate, dissolved oxygen concentration, and supply amount are relative and appropriately set according to the state of the lake.

  In addition, the method for removing sea cucumber according to claim 2 is characterized in that, in the method for removing sea urchin according to claim 1, water in which oxygen is dissolved at a high concentration is the surface water containing the sea bream. And

  That is, the invention according to claim 2 makes it possible to combine the supply means for the high-concentration oxygen-dissolved water and the supply means for the surface layer water, so that the apparatus or system configuration used to implement the present invention can be simplified. .

  In addition, the method for removing sea cucumber according to claim 3 is the method for removing sea urchin according to claim 1 or 2, wherein oxygen is first dissolved in water at a high concentration by a jet, and then bubbles are dissolved in high concentration oxygen-dissolved water. The main feature is that high-concentration oxygen-dissolved water is continuously supplied by an apparatus having a mechanism for separating from the water.

  That is, the invention according to claim 3 makes it possible to inactivate the sea urchin even by a jet flow, and stably supplies oxygen water to the bottom layer region so as not to generate an unintended water flow (for example, an upward flow) except for bubbles. It becomes possible to send out, and it becomes possible to promote decomposition without unevenness. As a device having such a configuration, for example, the technique of Japanese Patent No. 3845986 “gas-liquid dissolution apparatus” can be used.

In addition, the method for removing the sea cucumber according to claim 4 is the method for removing the sea urchin according to claim 1, 2 or 3, wherein the water pressure is 2.5 kg / cm ² or more between the water intake and the discharge. It is the main feature that goes through.

That is, the invention according to claim 4 can surely kill the water-bloom by the pressure change, and promotes the decomposition. The water pressure is indicated as gauge pressure. The discharge port may be simply positioned deeper than the water depth of 25 m, or a mode in which a water pressure of 2.5 kg / cm ² or more is secured by the water depth and the jet flow may be used.

  According to the present invention, it is possible to kill the watermelon, decompose it in the bottom layer, improve the anoxic state, cut off the growth cycle of the watermelon, and improve the lake. More specifically, according to the present invention (Claim 1), the water-bloom is inactivated by an environmental change such as a change in water pressure or a change in water temperature, and this is retained in the bottom layer area where the aerobic microorganism is activated. It can be decomposed continuously. Further, according to the present invention (Claim 2), it is possible to simplify the apparatus or system configuration used to implement the present invention. Further, according to the present invention (Claim 3), it is possible to inactivate the sea cucumber even by a jet flow, and stably to the bottom layer region without causing an unintended water flow (for example, an upward flow) except for bubbles. Oxygen water can be sent out to promote decomposition without unevenness. In addition, according to the present invention (claim 4), the sea cucumber can be surely killed by the pressure change, and the decomposition is promoted.

It is the conceptual diagram which showed a mode that the system used for implementation of this invention was applied to the lake. It is the figure which showed the structural example of the oxygen supply apparatus among the systems used for implementation of this invention. It is the schematic diagram which showed notionally the dissolved oxygen distribution in a dam based on a measured value. It is the schematic diagram which showed notionally the dissolved oxygen distribution after improving an anoxic state about the same dam as FIG. 3 based on the measured value. It is the photograph which showed the mode of the bottom mud of the dam before and after implementation of this invention. It is the figure which showed the example of a different system structure.

  Hereinafter, the present embodiment will be described with reference to the drawings. FIG. 1 is a conceptual diagram showing a state in which a system used for carrying out the present invention is applied to a lake.

  Blue sea bream grows rapidly when the conditions of nutrition, light, and water temperature are in place, especially when a large amount of nitrogenous and phosphorus-rich domestic wastewater flows into the lake and eutrophies. Then, once the blue sea bream occurs, the dead bodies pile up on the bottom of the lake and become sludge, and a vicious cycle occurs in which phosphorus elutes again from the sludge and becomes the sea bream's nutrients.

  As a result of intensive studies, the present inventor has invented a method for removing sea cucumber or a method for reforming a lake that is highly effective by introducing a simple system in a lake with a large real area and volume. . As shown in FIG. 1, the system for realizing this method is mainly composed of a surface water collection device 1 and an oxygen water supply device 2.

  The surface water collection device 1 sucks surface water containing the sea cucumber and sends this water to the oxygen water supply device 2 via the water supply hose 11. It is assumed that the surface water collecting apparatus 1 is appropriately provided with a filter that does not mix wood chips or leaves of leaves and takes in water. The surface water collecting device 1 is arranged at the substantially central portion of the lake where the sea urchin floats, but is stopped at this position by a buoy and anchor (not shown).

  The oxygen water supply device 2 mixes the surface water containing the sea cucumber and air (or oxygen) by a jet, and kills the sea bream by the water pressure while increasing the dissolved oxygen concentration. Furthermore, gas-liquid separation is performed, and liquid (mixed liquid of dead sea cucumber and high-concentration oxygen-dissolved water) is slowly and slowly discharged horizontally. The reason why the horizontal discharge is gentle is to improve the poor oxygen state of the bottom layer not by the water flow but by diffusion utilizing the water layer density difference. By horizontal discharge, the dissolved oxygen concentration in the bottom layer can be increased without unevenness depending on the position.

  Oxygen dissolved in the surface water is taken from an air guide hose (not shown) provided in the water supply hose 11 and the air after gas-liquid separation is exhausted to the water surface by an exhaust hose (not shown). Note that the exhaust gas may be appropriately recirculated and reused depending on the specification.

  As the configuration example of the oxygen water supply device 2, the one shown in FIG. As shown in the figure, the oxygen water supply device 2 includes a gas-liquid dissolution chamber 21 and a gas-liquid separation chamber 22 containing the gas-liquid dissolution chamber 21. In the gas-liquid dissolution chamber 21, air and surface water containing aquatic are urged and ejected to the dome-shaped top plate portion 212 by the nozzle 211. Due to the dome shape, the gas and liquid become jets, the bubbles become finer, and oxygen is dissolved in water efficiently. At this time, the lump of blue sea bream is also finely separated. As a result, the surface area of the sea bream is increased, and the decomposition proceeds efficiently by the aerobic microorganisms after being discharged to the bottom layer.

  In the gas-liquid separation chamber 22, high-concentration oxygen-dissolved water and bubbles that have not been dissolved in water flow in from the escape holes 213 provided in the lower portion of the gas-liquid dissolution chamber 21. The exhaust port 221 for exhausting is provided, and a supply port 222 for supplying high-concentration oxygen-dissolved water accompanied by a watermelon is provided in the lower part. An exhaust hose is connected to the exhaust port 221, and a discharge port arranged horizontally is connected to the supply port 222. It should be noted that the discharge port is enlarged so that the water flow is as gentle as possible.

The oxygen water supply device 2 is disposed in the bottom layer of 25 m directly below the surface water collection device 1. Although not shown, the oxygen water supply device maintains its posture by attaching a buoy to the top and placing the anchor on the bottom of the lake. Moreover, a pump and the like necessary for energizing are also provided as appropriate. The position of 25 m is a depth for destroying the gas sac of the sea urchin by water pressure, but the sum of the water pressure at the position where the gas-liquid dissolution chamber 21 and the water pressure by the jet flow are 2.5 kg / m ² (gauge Pressure), the water depth may be less than 25 m.

  By driving the surface water collection device 1 and the oxygen water supply device 2, the sea cucumber is removed and the lake is reformed as follows. First, when the oxygen water supply device 2 is driven, oxygen is dissolved in a high concentration in the water of the lake and is continuously supplied to the bottom layer region. Thereby, aerobic microorganisms are activated. In addition, the water at this time shall be taken in appropriately.

  FIG. 3 is a schematic diagram conceptually showing the dissolved oxygen distribution in the dam based on the actually measured values. In general, when the water-bloom is generated, the oxygen concentration in the bottom layer region is substantially zero. When the oxygen water supply device 2 is driven to stabilize the oxygen concentration, the oxygen concentration in the bottom layer is about 10 mg / l. FIG. 4 is a schematic diagram conceptually showing the dissolved oxygen distribution after improving the poor oxygen state for the same dam as in FIG. 3 based on the actually measured values. Although only the oxygen water supply device is shown in the figure, this makes it possible to achieve an oxygen concentration equal to or higher than that of the surface layer portion.

  After the oxygen concentration in the bottom layer region is stabilized, the surface water collection device 1 is driven. As a result, surface water is supplied to the oxygen water supply device 2 together with the blue water, the green water is killed by the original water pressure and the pressure urged by the jet, and the blue water mass is subdivided. At this time, Aoko's gas vesicles are also destroyed. By driving, high-concentration oxygen water containing blue sea urchins is discharged horizontally to the bottom layer region at a predetermined flow rate. Thereby, it becomes possible to maintain the activity of the aerobic microorganism while supplying oxygen water and the water-bloom, and to proceed with the decomposition of the water-bloom. The sea cucumber is killed by the temperature difference and the light intensity reduction.

  Since blue water is directly exposed to sunlight, the temperature may be slightly higher than the water temperature at the discharge position. Therefore, the water-blooming may rise slowly after discharge, but as the temperature of the surrounding water approaches, settling begins slowly (because the gas vesicles are removed and the specific gravity is greater than that of water). Then, it reaches the bottom layer with high activity of aerobic microorganisms and is decomposed. In addition, phosphorus produced by decomposition binds and precipitates with iron ions in water and accumulates at the bottom of the lake, making it possible to break the chain of nutrient sources. Further, the nitrogen content generated by the decomposition is also denitrified by the change in the low-layer oxidation / reduction atmosphere.

  In addition, the amount of surface water sucked in can be set as appropriate according to the dissolved oxygen concentration, the discharge amount, and the state of the lake. In relation to this, the water supplied to the oxygen water supply device 2 may be provided in a separate system from the surface water collection device 1 in order to adjust the oxygen concentration in the bottom layer and the decomposition rate of the sea bream.

Next, a specific example of this method will be described.
Conduct place Scale of prefectural S dam Dam Fully water level EL127.0
Effective water storage capacity 6.4 million cubic meters
Water level EL115.0 meter
Amount of water 500,000 cubic meter experiment start date April 2006
Oxygen water supply device Underwater type gas-liquid dissolution equipment (WEP system: Made by Matsue Doken Co., Ltd.)
Oxygen water supply capacity 120 cubic meters / hour 1 equipment installation location Upper lake bottom 0.5 meters to 18 meters (moving up and down)

  In the S dam, the dissolved oxygen concentration in the lower water area before the operation of the device was poor in the bottom layer as in FIG. 3, and the dissolved oxygen concentration was 2 mg / l or less. The dissolved oxygen concentration 27 days after the start of the apparatus drive was approximately 10 mg / l in the bottom layer, as shown in FIG.

  In this state, the black organic bottom mud (Aoko's carcass) deposited on the bottom of the lake was oxidized and became reddish. FIG. 5 is a black and white photograph of sludge (left figure: before driving, right figure: after driving). Moreover, when the oxidation-reduction potential of the bottom mud portion having a height of 5 mm from the bottom surface was measured before and after driving the apparatus, it was improved from −60 mv to +40 mv. From these results, it was confirmed that oxygen was sufficiently dissolved in the bottom layer and organic substances were decomposed by aerobic microorganisms.

In addition, Aoko (mainly Microkistis, Anabena) collected at S Dam and lake water are placed in a pressure vessel (10 ml), and the water pressure in the vessel is 2 kg / cm ² to 3 kg / cm ² (corresponding to a water depth of 20 to 30 m). And left for 30 minutes. Thereafter, the sea cucumber was taken out of the container and observed. The results are shown in Table 1. As shown in the table, when a pressure of 2.5 kg / cm ² (corresponding to 25 m) or more was applied, it was confirmed that the sea bream settled in water and the gas vesicles were destroyed. That is, it was also confirmed in the laboratory that the aquatic can be killed and settled by this method. In addition, even if the sea cucumbers sticked to each other to form a small lump or film, it was confirmed that the aggregates of the sea bream were extremely fine. In addition, since it does not take up to 30 minutes from water intake to discharge, gas vesicles may not be partially destroyed even at a water depth of 25 m. However, in this case, those in which the gas vesicles are not destroyed rise again to the surface of the water and are eventually removed, so that they are eventually removed.

  In carrying out the present invention, the system configuration is not limited to the configuration shown in FIG. FIG. 6 is a diagram illustrating a different system configuration example. As illustrated, the oxygen water supply device 2 may be separated from the surface layer water supply device 1. However, the water supply hose of the surface water supply device 1 is disposed deeper than a water depth of 25 m so as to discharge the surface water containing the sea cucumber in the horizontal direction. According to this structure, since the supply amount of oxygen water per unit time can be improved, the removal rate can be improved.

  In dam lakes, which are used as water supply sources, bad smell caused by sea lions is prevented, water purification costs at water treatment plants can be reduced, and safe drinking water can be supplied. In addition, in lakes and dam lakes, which are popular as sightseeing spots, it is useful for landscape conservation because aquatic can be removed in a short time. In addition, if the lower water of lakes and dam lakes is maintained in an aerobic environment and the occurrence of blue sea urchins can be prevented, it will be possible to release rainbow trout, rainbow trout, etc. This could lead to the creation of new industries.

DESCRIPTION OF SYMBOLS 1 Surface water collecting apparatus 2 Oxygen water supply apparatus 11 Water supply hose 21 Gas-liquid dissolution chamber 22 Gas-liquid separation chamber 211 Nozzle 212 Top plate part 213 Escape hole 221 Exhaust port 222 Supply port

Claims (4)

It is a method for reforming lakes where the bottom layer has become hypoxic and the surface layer has blue sea bream.
While dissolving oxygen at high concentration in the water of the lake, supplying this continuously to the bottom layer region and maintaining the bottom layer region to be above the predetermined oxygen concentration,
A method for removing sea cucumber, characterized in that surface water is taken together with the sea bream and discharged to the bottom layer area at a predetermined flow rate substantially horizontally.   The water for dissolving oxygen at a high concentration is the surface layer water containing the watermelon. The method for removing the watermelon according to claim 1.   A high-concentration oxygen-dissolved water is continuously supplied by a device having a mechanism for first dissolving oxygen in water by a jet and then separating bubbles from the high-concentration oxygen-dissolved water. 3. The method for removing the sea cucumber according to 1 or 2. 4. The method for removing sea cucumbers according to claim 1, 2 or 3, wherein a step of forming a water pressure of 2.5 kg / cm ² or more is performed between water intake and discharge.