JPH0699196A - Clarifying method for water area - Google Patents

Abstract

PURPOSE:To efficiently clarify water area by holding the whole water area in an aerobic state while discharging suspended solid in the water area to the outside thereof. CONSTITUTION:Water 4 is pumped up from the part wherein flow is least in water area by a pump 3 and filter by a filter 2. Filtered water 5 is diffused in the whole water area P by an aeration agitator 1 provided in the water area P. Thereby the water area contaminated by phyto-plankton or the like is clarified.

Description

Detailed Description of the Invention

[0001]

The present invention relates to suspended matter (S) such as phytoplankton in water areas such as reservoirs, lakes and moats.
The present invention relates to a method for purifying a water body in which S) is removed and the purification is efficiently performed.

[0002]

2. Description of the Related Art In many closed waters such as lakes, ponds and moats, eutrophication is caused by the inflow of domestic wastewater, and phytoplankton grows abnormally to cause offensive odors or coloring, or in the case of water supply in case of water source. It causes the problem of filtration failure. As a method for purifying such a water area, a method of performing aeration with a blower or generating a circulating flow in the water area with an agitator has been attempted.

[0003]

However, although these methods have the effect of keeping the water area aerobic and suppressing the growth of algae, they have almost no effect of suppressing the growth of phytoplankton, and the transparency and There was a drawback that the color could not be improved.

An object of the present invention is to efficiently purify a water body by keeping the whole water body aerobic while discharging suspended solids (SS) in the water body to the outside of the water body.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and water in a body of water is pumped up to remove suspended solids by using a filtering device, and the filtered water is aerated and agitated. Disperse the whole water area by a machine to purify the inside of the water area and homogenize it, and reduce the concentration of suspended solids, especially phytoplankton, to improve transparency, improve the color of water and prevent the generation of foul odors. What is done is the gist.

The aeration agitator 1 is floated on the water surface by a float or fixed to the water bottom in a water area P such as a lake or the like where water does not flow in and out. The aeration stirrer 1 is, as shown in FIG.
It is composed of a submersible motor 11, a screw 12, and a ventilation pipe 13, and has a structure in which air above water is sucked from a ventilation pipe inlet and sent to the tip of the screw 12 via a hollow shaft of the submersible motor 11. One to several units are provided in consideration of shape and capacity. In addition, the water area is provided with a submersible pump 3 for pumping water in the water area. For the submersible pump 3, use a floating skimmer type that can be fixed to a float and absorb water-bloom etc. on the water surface, or if using a normal submersible pump, for fixing the pump so that the mud at the bottom of the water is not sucked and the pump is not blocked. Consider the stand, etc. The filtering device 2 is usually installed on the ground, and the raw water 4 pumped by the submersible pump 3 is filtered, the treated water 5 is guided to the tip or suction part of the aeration mixer 1, and the cleaning drainage 6 of the filter medium is discharged out of the water area. As shown in FIG. 2, the filtering device 2 supplies the raw water 4 into the drum 21 while rotating the drum 21 covered with the filter cloth.
It is convenient to backwash the surface of the filter cloth with the cleaning spray 23 from the outside of the drum while filtering the outside of the drum.
You may use the common filtration device which filters using sand or various filter materials.

[0007]

When the aeration agitator 1 is operated, the rotation of the screw 12 produces a negative pressure at the tip of the screw. The screw and the shaft of the submersible motor 12 are hollow, and the vent pipe 13 is connected to the suction port 13 at the tip of the vent pipe by the generated negative pressure.
The outside air is sucked from a, is sent to the tip of the screw, and is sheared by the edge of the screw to be ejected as fine bubbles. A water flow is generated by the rotation of the screw, and the fine bubbles and dissolved oxygen form a circulating flow in the water area. In the case of water with a lot of phytoplankton, oxygen is generated by photosynthesis during the daytime, but at night, phytoplankton only breathes and consumes dissolved oxygen in water rapidly to become anaerobic, so it is necessary to perform aeration. is there. Further, since the aeration stirrer performs stirring while supplying air, the resistance force applied to the stirring blade is small, and the stirring can be performed with a smaller power than that of the dedicated stirring machine. Submersible pump 3
Is installed in the stagnation part where the flow is the smallest in consideration of the flow by the aeration mixer 1. Therefore, in the case of the water area shown in FIG. 1, it may be installed at the pond end or the pond center shown. The filtered raw water 4 pumped by the submersible pump 3 is sent to the inside of the drum 21 of the filtering device shown in FIG. Due to the difference in water level between the raw water inside the drum and the filtered water inside the filter tank 22, clear water in the raw water passes through the filter cloth, is guided to the outside of the drum, and is returned to the water area as treated water 5. Since SS components such as phytoplankton in the raw water adhere to the inner surface of the filter cloth to cause filtration resistance, the cleaning spray 23 is sprayed from the outer side of the drum upper portion while rotating the drum 21 to attach S.
The S component is dropped from the filter cloth, collected in the wash water receiver 24, and discharged. This backwashing wastewater may be discharged to the sewer etc. depending on the stand conditions etc., but it is preferable to discharge the solid matter in the wastewater after concentrating and dehydrating it.

Example 1 The aeration stirrer 1 and the filtration device 2 of the present invention were installed in a pond having a capacity of 1200 cubic meters as shown in FIG. 1, and filtration was performed at 200 cubic meters / day while aerating and stirring the entire pond. went. After a lapse of 30 days, stop the aeration stirrer, continue filtering only, and sample water at a, b, and c 3 points to SS
(Floating substances) was analyzed. The time-dependent change in SS concentration is shown in FIG.

As shown in FIG. 4, the whole pond is sufficiently agitated for 30 days when both are operated, and the values at a, b, and c are almost the same, and 55 m at the start of operation.
SS decreased from g / l to about 22 mg / l, but after 30 days when aeration and stirring were stopped, the values of a, b, and c began to gradually fluctuate, and after 60 days, Increased the SS concentration to about 38 mg / l on average. This is because the aeration and agitation were not performed, so the filtered water could not be sufficiently diffused throughout the pond and an SS distribution occurred, and the increase in the SS concentration was due to the increase in the growth rate of phytoplankton when the aeration was stopped. it is conceivable that.

Example 2 A small capacity (about 240 cubic meters) that hardly causes water quality distribution
The aeration stirrer 1 and the filtering device 2 of the present invention are installed in the circular pond of No. 1, and only the filtering device is operated for the first 40 days,
Filtration was performed at 100 cubic meters / day. After the 40th day when the SS concentration in the pond was stable, the operation of the aeration stirrer was added, and the purification was further promoted by both operations. Since there was almost no difference in SS concentration depending on the sampling position, sampling was performed with one central position as the representative position. The time-dependent change in SS concentration is shown in FIG.

According to FIG. 5, the limit of the SS concentration in the pond was 27 mg / l when only the filtration device was operated, whereas it could be lowered to 9 mg / l when the aeration stirrer was combined. When the growth rate of phytoplankton was measured 35 and 75 days after the start of operation, 3
In the case of filtration only on the 5th day, 1250g of phytoplankton increased per day, whereas when the aerator on the 75th day was used, the growth amount of 380g per day reached the equilibrium state, so the growth amount of each was increased. That is, the amount corresponding to is discharged from the system by the filtration device.

On the other hand, FIG. 6 shows changes with time in the DO (dissolved oxygen) concentration in the pond on the 35th and 75th days, and on the 35th day, the DO was 1 mg from 0 o'clock to 10 o'clock.
/ L or less and completely anaerobic,
When combined with an aeration stirrer, an aerobic state of 5 mg / l or more can be maintained at all times. During the experiment, the inflow into the pond and the outflow from the pond were blocked to create a completely closed system, but mud was accumulated at the bottom of the pond, and this bottom mud contained a large amount of nutrient salts such as nitrogen and phosphorus. Has been. This nutrient salt is retained in the pond mud without elution under aerobic conditions, but it elutes from the bottom mud into water under anaerobic conditions. Therefore, in the case of only filtration, the bottom mud is anaerobic at night and nutrient salts are supplied from the bottom mud to the water, so that phytoplankton grows in large amounts, whereas when the aeration stirrer is combined, Since it is possible to suppress the nutrient salt elution, the growth amount of phytoplankton is also small. Therefore, it is considered that the purification effect on the pond is improved and the water quality is improved even if the SS removal amount by the filtration device is the same.

To summarize the above, (1) With the aeration stirrer alone, it is possible to homogenize the water quality in the water area by the agitation flow and suppress the multiplication of water-blooms floating on the water surface. Can be kept. However, there is no effect of removing SS in the pond and improving the water quality. (2) The filter device alone can remove SS in the pond and improve the water quality. Moreover, the water quality in the water area can be made uniform to some extent by the shape and size of the pond, the pumping of raw water from the pond, and the returning position of the treated water. (3) By combining both, the individual functions are combined and filtration is performed while suppressing the growth of phytoplankton by the aeration agitator, so the SS concentration in the pond is the same when the filtration device alone Can be reduced, and better water quality can be obtained.

[0014]

According to the present invention, the water in the water area is pumped up, the suspended matter is removed by using the filtration device, and the filtered water is diffused to the whole water area by the aeration stirrer while being aerobically aerated. As a result, the concentration of suspended solids in the pond can be reduced to improve transparency, the color due to phytoplankton can be removed, and the bad odor due to anaerobic decay of organic matter can be prevented.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a water purification method of the present invention.

FIG. 2 is an explanatory view of an aeration stirrer.

FIG. 3 is a diagram showing an embodiment of the filtration device used in the present invention.

FIG. 4 is a graph showing the change over time in the concentration of suspended solids in the first example.

FIG. 5 is a graph showing changes over time in the concentration of suspended solids in the second example.

FIG. 6 is a graph showing the change over time in the dissolved oxygen concentration.

[Explanation of symbols]

 P Water area 1 Aeration agitator 2 Filtration device 3 Submersible pump 4 Raw water 5 Treated water 6 Washing wastewater

Claims (2)

[Claims] 1. A phytoplankton or the like is obtained by filtering the water pumped from the portion with the least flow in the water area with a filtration device and diffusing the filtered water throughout the water area with an aeration stirring device installed in the water area. A method for purifying polluted water bodies, which is characterized in that it is adapted to purify polluted water bodies. 2. The water area according to claim 1, wherein the aeration and agitation device is a screw type aeration device that utilizes negative pressure generated by rotation of a screw to aerate water while self-sufficiently supplying air above the water. Purification method.