JPH0691283A - Water area cleaning method - Google Patents

Abstract

PURPOSE:To effectively clean the water area polluted with phytoplanktons and make the size of a filtration apparatus compact. CONSTITUTION:Water in the water area P of such as lakes and marshes, moats, ponds, etc. is pumped, filtered through a filration cloth/filtration material and then ozone-containing air is injected into the filtered water 12 to sterilize the microbes such as phytoplanktons which remain in the filtered water 12. The water area P is cleaned by returning the water 14 treated with ozone to the water area P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the purification of closed water areas such as lakes, castle moats, and ponds, and more particularly to a method for cleaning water areas contaminated by eutrophication and growth of phytoplankton.

[0002]

2. Description of the Related Art Conventionally, for purification of polluted water,
A method of aerating and aerating the inside of the body of water by providing an aeration stirring device, or pumping water in the body of water and returning the water filtered by a filter device to the body of water has been used.

[0003]

However, in the former case, the amount of phytoplankton cannot be reduced in a water area rich in phytoplankton, and in the latter case, the amount of phytoplankton can be reduced to some extent. However, there is a limit to the effect, and when the fine plankton that have passed through the filter tank are returned to the water area, the number increases again due to proliferation, and there is a drawback that the effect cannot be obtained unless a large amount of filtration is performed.

The present invention is to provide a method for effectively purifying water contaminated with phytoplankton.

[0005]

Means for Solving the Problems The present invention has been made in order to achieve the above-mentioned object, and after water in a water area such as a lake, a moat, or a pond is pumped and filtered using a filter cloth / filter material. The gist of the present invention is to purify a water area by injecting ozone-containing air into the filtered water to sterilize microorganisms such as phytoplankton remaining in the filtered water and returning the ozone-treated water to the water area.

[0006]

When the phytoplankton in the water area is filtered using a filter cloth, the phytoplankton having a relatively large particle size of 5 to 10 microns or more can be removed by the filter cloth, but the plankton of 5 microns or less is It can hardly be removed, and the removal rate is usually about 50%. The minute plankton that could not be removed by the filtration tank will multiply in the water area when it is returned to the water area. Therefore, in order to purify the water area, at least 1
Only one cycle needs to be filtered within one week.
Therefore, in the present invention, the filtered water is aerated with air containing ozone to sterilize the plankton remaining in the filtered water and then return it to the water area.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. P is a polluted water area such as a pond, where many nutrient salts such as nitrogen and phosphorus are accumulated and phytoplankton is actively growing. A pump 1 is provided in a dead zone or a zone with severe pollution in the water area to pump water containing phytoplankton and send it to the filtering device 2. The filtration device 2 is a filtration device that uses a filter cloth, a fibrous filter material, or the like, and is preferably a system that can perform filtration at a higher speed than conventional sand filtration that filters approximately 200 cubic meters per day.

In the ozone reaction tank 3, air containing ozone is blown into the filtered water 12 to bring it into contact with residual organic matter such as phytoplankton. For ozone, the air from the compressor 4 is removed by a drier 5 to remove moisture in the air and sent to an ozone generator 6, where a part of oxygen is converted to ozone by silent discharge or the like, and then an ozone reaction tank. Insufflate to 3. However, the method of generating ozone-containing air is not limited to this.

The ozone-containing air is conveniently aerated by using an air diffuser or an air diffuser, but the method is not necessarily limited to this, and it may be combined with a mechanical aerator or a static mixer. A method of mixing by using is also effective. The ozone reaction tank 3 may also be provided with an air diffusing tower separately, but ozone-containing air may be injected into the filtered water tank by using the filtered water tank of the filtering device. The treated water 14 that has been brought into contact with ozone is sent to the front and rear of an agitator provided for agitating the inside of the water area or the aeration agitator 7, and diffused throughout the water area. However, the stirrer can be omitted depending on the shape and size of the water area.

Next, the operation and action of the present invention will be described. Figure 1
In 1, the pumped water 11 is sent to the filtering device 2, and the suspended matter in the water is removed by the filter medium. The suspended solids adhering to the filter medium are backwashed continuously or at regular time intervals so as to be separated from the filter medium and a small amount of backwash water 1
It is discharged from the filtration device as 3. The backwash drainage 13 is discharged to a sewer or the like, or concentrated / dehydrated and carried out as sludge to the outside of the system. On the other hand, the filtration device is usually 5 to 1
Particles of 0 micron or larger can be blocked and removed by a filter medium, but since plankton having smaller particles passes through the filter medium, it is brought into contact with ozone-containing air in the next ozone reaction tank 3 to sterilize the plankton. After that, the treated water 14 is returned to the water area. Since the stirrer 7 is provided in the water area, the treated water is diffused throughout the water area, and the entire water area is gradually purified.

[0011]

[Example 1] A polluted pond of about 150 cubic meters was partitioned into three parts, each reaching a water area of about 50 cubic meters,
Purification was performed by the following three methods. However, the inflow pipe to the pond was blocked and the drainage from the pond was limited to overflow. (A) ... By the method of the present invention, after filtering 50 cubic meters of water per day with 5 cubic meters of water,
When aeration is performed with ozone-containing air and the treated water is returned to the pond. (B) ... When ozone is not treated and only 5 cubic meters of water per day is filtered and the filtered water is returned to the pond. (C) ... When ozone treatment is not performed and 15 cubic meters of water are filtered per day and the filtered water is returned to the pond. FIG. 2 shows the time-dependent change in the SS (suspended substance) concentration in each water area when operating for about 3 months by these three methods.
For a volume of pond water of 50 cubic meters, a filtration volume of 5 cubic meters per day, that is, one circulation in 10 days, removes slightly more than the amount of phytoplankton produced in the pond. As shown in (B), SS was only slightly decreased, and when the filtration amount was increased so as to make one circulation of 15 cubic meters per day for about 3.3 days, (C) significantly decreased SS in the water area. From 60 mg per liter at the start to 24 mg per liter after 60 days, it was almost stable. On the other hand, in (A) of the present invention, the amount of filtered water is (B).
Same as the above, although it is as small as 5 cubic meters per day, it returns ozone-treated and sterilized water to the water area,
The SS concentration decreased more rapidly than that of the large amount of filtered water (C), and the SS concentration in the stable state was also low, which was about 11 mg per liter.

[0012]

According to the present invention, a filter device and an ozone generator are combined, the water pumped from the water area is filtered, and then ozone-containing air is brought into contact with the filtered water to contain phytoplankton contained in the filtered water. Since the microorganisms are sterilized and returned to the water area, the size of the filtration apparatus can be made smaller than in the case where the filtration apparatus is used alone, and the effect of purification is great, and the ozone-containing air is directly injected into the water area. There is no fear of accidents such as death of fish due to
Since ozone is injected into the filtered water from which most of SS has been removed in advance, there is an effect that a small amount of ozone can be effectively treated.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a method for purifying a water area of the present invention.

FIG. 2 is a graph showing changes over time in the concentration of suspended solids in water according to the present invention.

[Explanation of symbols]

 P Water area 1 Pumping pump 2 Filtration device 3 Ozone reaction tank 4 Compressor 6 Ozone generator 7 Aeration stirrer

Claims (1)

[Claims] 1. A phytoplankton or the like remaining in the filtered water obtained by pumping water from water bodies such as lakes, moats, and ponds, filtering it using a filter cloth / filter material, and then injecting ozone-containing air into the filtered water. The method for purifying a water body, which comprises purifying the water body by sterilizing the microorganisms described above and returning the ozone-treated water to the water body.