JPH0688017B2 - Device for removing contaminants in liquid - Google Patents

Description

TECHNICAL FIELD The present invention relates to the fields of aquaculture, live fish transportation, fish raising, and the like, and to the food industry, for example, a device for removing pollutants in the treatment of waste water such as rice bran juice. Is.

[Prior Art] A live fish farming or transportation system currently in practical use is mainly intended to maintain the life of live fish by supplying air or pure oxygen to the water. Even if they could be raised, it was difficult to maintain a hygienic water environment due to the accumulation of waste products in the water.

In particular, with regard to the removal of viable bacteria such as Vibrio bacteria, there is no effective means for transporting live fish, raising fish, etc., and it is the actual situation that contamination of live fish with Vibrio bacteria is left.

However, improvement in removing harmful bacteria and pollutants is an urgent issue from the viewpoint of human hygiene and life support of fish.

Further, in the treatment of a large amount of waste water generated in the food industry, such as rice bran juice, a large-scale apparatus using an aeration tank and a precipitation tank is required, and a simpler apparatus is desired.

Many examples of utilizing bubbles as a flotation process are known as related to the technique of removing suspended solids in water using bubbles. In this method, air is discharged into water through an air diffuser to form bubbles, and pollutants or metal components are attached to the bubbles to float and separate, and a surfactant is used for the purpose of generating bubbles.

However, the size of bubbles used in the flotation method is large, and it is not suitable for removing harmful bacteria such as Vibrio bacteria.To date, examples of removing Vibrio bacteria using bubbles are used. I can't see it.

In addition, it is needless to say that it is inappropriate to use a surfactant for foam formation in the life support of fish and the food industry.

[Problems to be Solved by the Invention] Therefore, an object of the present invention is to use pollutants such as harmful bacteria in wastewater of aquaculture, live fish transportation, fish breeding, etc., and wastewater of the food industry by using bubbles and surface-active them. It is intended to provide a device for continuous removal without using an agent.

[Means for Solving the Problems] In order to solve the above problems, the present inventors have repeatedly studied the following items.

(1) In transportation of live fish or food industry, it is not possible to add a surfactant to be added for water foaming. Therefore, it is necessary to make foaming into ultrafine bubbles. Therefore, an appropriate aerator should be adopted. I have to.

The aeration device according to the invention of Ryozaburo Sato, one of the inventors of the present invention (Japanese Patent Publication No. 62-34436 etc.), is suitable for easily generating stable bubbles by ultrafine bubbles. use.

(2) It is necessary to remove harmful bacteria in the environment including water, particularly Vibrio bacterium, by bubbles when considering the life support of fish in transportation of live fish and human hygiene in live fish dishes where fish are eaten raw.

(3) When removing bubbles continuously, it is necessary to keep the position of the interface between the bubbles and the liquid at a substantially constant position. Otherwise, not only bubbles but almost all of the water in the water overflows to save the fish, and if no bubbles continue for a long time, the components secreted by the fish will accumulate and have a bad effect.

Therefore, it is necessary to perform control capable of coping with these.

(4) The device must be compact and capable of efficiently separating bubbles.

For that purpose, it is necessary to make the best use of the features of the aeration apparatus by the present inventors and to make up for its drawbacks.

(5) In treating sewage such as rice bran soup with foam, it is necessary to have a treatment capacity capable of treating even if the speed of running water is increased.

The present invention has been completed as a result of intensive studies on the above-mentioned items.

That is, according to the present invention, there is provided a device for removing contaminants in liquid, which has the following configuration.

(1) A liquid tank for storing liquid and a hollow rotating shaft installed in the liquid tank are provided, and a lower end of the hollow rotating shaft sandwiches a vane along the axial direction and the vane vertically. A plurality of air holes are provided in a portion of the hollow rotating shaft sandwiched by the plate members and the air is sucked into the shaft by using a negative pressure generated by the rotation of the hollow shaft. A device for removing contaminants in liquid, characterized in that a bubble generating means for discharging ultra-fine bubbles from a hole in a horizontal direction with respect to a rotation axis is formed.

(2) The partition plate for canceling the rotation of the liquid generated by the rotation of the hollow shaft is provided in the liquid tank, and the liquid surface position control means is attached to the liquid tank. Inside contaminant removal device.

(3) While the ultrafine bubbles in the liquid float from the lower part to the upper part of the liquid tank, the negative pressure generated by the rotation of the hollow shaft causes the liquid to flow down from the upper part to the lower part in the liquid tank. Device for removing contaminants from the liquid of 1).

The pollutant removal device of the present invention has one major feature in that it employs an aeration device (hereinafter, referred to as a carvas aerator) by the present inventor as a means for generating bubbles.

The carvas aerator, as shown in FIGS. 1 and 2 by way of example, is provided with a liquid tank for storing liquid and a shaft 13 rotated at a high speed by a motor. The rotary shaft 13 is a hollow shaft, the upper end of which is connected to a motor 5 installed on the upper surface of the liquid tank, the lower end of the rotary shaft extends near the bottom of the tank, and a bubble generating means is provided at the lower end. Has been formed. That is, a blade 16 along the axial direction, an upper disk (plate material) 14 and a lower disk (plate material) 15 that sandwich the blade 16 vertically are attached to the lower end of the rotary shaft 13, and these are installed. The shaft 13 rotates to rotate integrally. Also, as shown in the figure, the upper and lower plate materials
A large number of air holes 17 are provided on the peripheral surface of the rotary shaft 13 sandwiched between the fourteen and fifteen.

When the blade 16 rotates integrally with the shaft 13 in the water, a negative pressure is generated behind it, whereby air is sucked into the hollow shaft from the upper end of the shaft 13, and this air passes through the shaft and passes through the shaft. It is discharged into the liquid through the air holes 17 at the lower end. Since this air is discharged from the air hole 17 in the rotating state, unlike the generation of bubbles due to the suction of air by simply stirring the liquid, it is far more than the bubbles generated by the conventional self-suction type bubble generator of this type. The minute ultrafine bubbles 18 are discharged into the liquid, and the ultrafine bubbles 18 are further separated by the centrifugal force of the rotating shaft 13 into the upper and lower discs 1.
The particles are guided by 4 and 15 and dispersed in a horizontal plane perpendicular to the rotation axis 13.

As described above, the feature of the device of the present invention is that the ultra-fine bubbles 18 are generated by the bubble generating means, and the movement direction thereof is generated in the horizontal plane perpendicular to the rotation axis, and in the plane perpendicular to the rotation axis. In addition to improving the mixing with water by dispersing air bubbles by centrifugal force, it is possible to make good holes in a narrow water tank.

Bubbles have the function of attaching suspended solids of pollutants floating in water, and the attachment is basically proportional to the surface area of bubbles, but bubbles have a large surface area as they become minute aggregates. The performance of the pollutant removal device that utilizes the above depends on how ultra-fine bubbles can be generated.

In that respect, the carvas aerator is optimal for the large-scale generation of ultra-fine bubbles, and can be said to be superior to any other bubble generation mechanism.

Further, a further feature of the present invention is that the ultrafine bubbles generated by the above apparatus are found to be excellent in the uptake of bacteria such as Vibrio bacterium. That is, it is considered that ultrafine bubbles take in bacteria such as Vibrio bacteria in water into the bubbles as will be apparent from the following examples, and that it is possible to effectively remove Vibrio bacteria by separating the bubbles. Is the greatest feature of.

Next, by detecting the boundary surface between the foam and the water surface and the upper surface of the foam as a detailed mechanism, the water surface in the pollutant removal device is always kept at an appropriate height, and thereby the overflow of the foam is kept optimal. . The discharge valve was controlled as this means.

On the other hand, it is desirable that the bubbles for removing pollutants rise stably and quietly, but the vector of rotation given by the Carvas aerator is detrimental to the generation of stable bubbles. Therefore, in order to counteract this rotation vector, improvements such as the provision of vertical partition plates (baffle plates) were added to increase the practicality by maximizing the amount of water that can be processed in a small tank, and rice in other food industries. It has also made it possible to dispose of sewage such as Nojiru soup.

[Examples] Hereinafter, the apparatus of the present invention will be described with reference to Examples.

FIG. 1 shows the transportation of sea bream and the after transportation as an embodiment of the present invention.
It shows an outline of a live fish tank equipped with a pollutant removal device that was tested for 48 hours.

In FIG. 1, the fish tank 1 has a tank capacity of 950 and seawater of 890.
And 50 sea bream 3 (weighing about 1 kg / tail) inside. The carvas aerator 4 is rotated by a motor 5 to release air into water and create bubbles. Motor 5
Is for 400W.

Seawater 2 is pumped out of the fish tank 1 by the pump 6 and circulates in the device. The bubble removing duct 7 collects bubbles floating on the surface, and the bubbles are accumulated in the bubble reservoir 8 and liquefied, and are accumulated in the liquefied water reservoir 9 and discharged to the outside of the system by the drain valve 10.

On the other hand, the seawater from which bubbles have been removed passes through the filtration device 11 and the pipe 12
Returned to the fish tank 1. The filtration device is activated carbon,
Composed of zeolite and mineral stone. Using this device, 50 live fish (sea bream) were transported by 50km truck, and then the test measurement was conducted for a total of 48 hours.

The measurement was carried out for each item of water temperature, turbidity, dissolved oxygen, and soluble organic matter.

FIG. 3 shows changes in water quality with respect to elapsed time when the Carvas aerator 4 was operated in the pollutant removal device.

The water temperature in the fish tank is approximately constant as shown by WT (●) 16.6〜
It was kept at 17.1 ° C.

The pH (▲) of the fish tank water was pH 8.19 before release, but it temporarily decreased twice with the passage of time, and then gradually increased to pH 7.
Recovered to 86. The decrease in pH is considered to be due to the increase of NO ₃ nitrogen concentration and the increase of CO ₂ concentration. The dissolved oxygen concentration (DO) (○) in the fish tank water was kept almost saturated (7.61 mg /, 17 ℃). This is due to the supply of oxygen to the water, which exceeds the oxygen consumption of the sea bream by the Carvas aerator.

Soluble organic matter (DOC) (■) in fish tank water
Although it was 6.2 mg / h, it increased linearly at a rate of 0.7 mg / h for about 15 hours, decreased after 15 hours, and low at about 0.07 mg / h after 27 hours. Increased. On the other hand, the DOC concentration (not shown) of foamed liquefied water was 49.5 mg / in the first 6 hours, but 923 mg / in the 39 to 45 hours.
Reached a high concentration.

Although DOC is highly concentrated in foam liquefied water, it was understood that it is important to always carry out foam overflow appropriately and in large quantities.

On the other hand, the turbidity (△) of the fish tank water was kept constant and did not increase during the whole experiment, indicating that the cleaning effect of water was obtained by removing bubbles.

This is explained in more detail in Fig. 4. From the measurement of the turbidity value of the foamed liquefied water, if the mud content is not removed by the foam and continues to increase, the turbidity is shown by the dotted line (●). Will reach 11 degrees after 45 hours. As shown by the solid line (∘), the removal by bubbles kept the temperature below 2 degrees, showing a great effect by the removal of bubbles.

On the other hand, the greatest result discovered in this experiment is the reduction of bacterial bacteria, especially the vibrio pathogenic bacteria, by removing bubbles as shown in FIG.

General viable bacteria (○) in fish tank water was 3.1 × 10 ³ (CFU / m
l) increased about twice immediately after releasing fish, and increased to 5.4 × 10 ⁵ 27 hours later, but no further increase was seen 48 hours later, while foamed liquefied water General viable bacteria (●) increased from 6.7 × 10 ⁵ immediately after release to 5.9 × 10 ⁷ after 27 hours and to 7.0 × 10 ⁷ after 48 hours, up to about 10 ⁸ orders, and removal effect by bubbles I found out that there is.

On the other hand, the vibrio bacterium that causes an accident of poisoning when eating raw fish, as shown by △ in Fig. 5, was detected only in extremely low values in the fish tank water from the start to the end of the experiment. 4.2 × 10 ³ after 27 hours from water (see ▲ in the figure)
(CFU / ml), and after 48 hours, a high concentration of 3.9 × 10 ⁴ (CFU / ml) was detected.

Analysis of the above test results reveals that the Vibrio bacterium is more efficiently concentrated in the foam, and the cause may be that the size of the bacterium is larger in the Vibrio bacterium. .

The amount of bubbles generated (speed) is the average when expressed by the amount of liquefied water.
It was 210-225 ml / h. The total amount of water liquefied from bubbles was as low as about 1.2% in 48 hours with respect to the amount of water in the first fish tank (890), and it is estimated that the water quality improvement due to bubble separation will be greater by increasing this amount.

On the other hand, immediately after putting the fish in the aquarium, immediately after the transportation vehicle starts running, tension is applied to the fish, so a large amount of fish secretions are generated and a large amount of foam is generated, and foam overflows from the foam overflow outlet. It is visually observed, and at other times, it is observed that the foam liquefied water does not come out. Therefore, it is preferable to control the overflow rate of the foam depending on the situation.

FIG. 6 is an operation explanatory view of the improved apparatus for removing contaminants such as Vibrio bacteria with carvas aerator, which illustrates the present invention.

The water tank 19 contains aquarium water (including fish) or liquid such as rice bran juice.

The water in this water tank 19 is removed by the water absorption pump 20 to remove bubbles.
Water is sent to the upper part from Carvas aerator 23 through pipe 22 to 21.

Carvas aerator 23 has a hollow shaft 25 by a motor 24
The vibrio contained in the water is emitted radially in a plane (horizontal plane) perpendicular to the flow of water that is rotated at high speed in the water and descends the ultrafine bubbles 26 through the water to improve the mixing with the water. Bacteria such as bacteria and contaminants are adsorbed on the bubbles and floated.

It is important that the floating bubbles rise as quietly as possible in order to improve the adsorptivity of the bubbles.

At that time, the rotational velocity vector of the ultrafine bubbles 26 generated by the carvas aerator 23 is harmful to the stable rise of the bubbles.

Therefore, a partition plate (baffle plate) 27 is placed inside the tank so as to cancel the rotation of water.

By this action, the bubbles rise gently, and the boundary between the bubbles collected on the liquid surface and the liquid surface sometimes becomes an emulsion state. As a result, not only bubbles but also water may overflow from the bubble overflow outlet 28, and water may suddenly enter the receiving tank 29.

To avoid this, carefully adjust the liquid level 30 to the bubble overflow outlet 28,
It is required to keep it at an appropriate level.

Therefore, the liquid level is detected by the small floating body 31 floating on the liquid level 30 and the valve 33 at the outlet 34 of the tank 21 is controlled by the sensor 33 attached to the upper part of the bar 32 which moves up and down accordingly.

As described above, it is also a great feature of the present invention that it is possible to maintain the liquid level at an optimum height, and that a control circuit that automatically controls the valve 35 of the outlet 34 is incorporated to maintain the height of the water level. .

On the other hand, in another test using this device, the higher the water feed rate, the better the foam generated, and the water feed rate was such that the amount of water in the bubble removal tank 21 was completely circulated in one minute or this. It has been confirmed that the speed may be 2 to 3 times higher, and the device of the present invention is considered to be effective not only for transporting live fish but also for treating water containing pollutants such as rice bran juice in the food industry.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an example of a live fish tank equipped with the pollutant removal device of the present invention, FIG. 2 is a perspective view of an example of an aeration device used in the device of the present invention, and FIG. 3 is a live fish tank water by the device of the present invention. Water temperature (WT), soluble organic carbon (DOC), dissolved oxygen concentration (DO), turbidity (Tur
bidity) and a graph showing changes in pH with time, and FIG. 4 shows changes with time in turbidity of aquarium water when the device of the present invention is not used, which is also estimated from turbidity of aquarium water and turbidity of foamed liquefied water. A graph showing the same, FIG. 5 is a graph showing a general viable cell count, a viable cell count of a live fish aquarium water and a general viable cell count of a foam-liquefied water, and a time-dependent change of the vibrio cell count by the apparatus of the present invention, and FIG. It is a schematic diagram of another example of a pollutant removal device according to the invention. Symbols in the figure: 1 …… Fish tank; 2 …… Seawater; 3 …… Sea bream; 4 …… Aeration device; 5 ……
Motor; 6 ... Pump; 7 ... Foam removal duct; 8 ... Foam reservoir; 9 ... Foam liquefied water reservoir; 10 ... Drain valve; 11 ...
Filtration device; 12 ...... pipe; 13 ... rotating shaft; 14 ... upper disk; 15
...... Lower disk; 16 ...... Vane; 17 …… Hole; 18 …… Ultra-small bubble; 19
…… Water tank; 20 …… Suction pump; 21 …… Bubble removal tank; 22…
… Pipe; 23 …… Aerator; 24 …… Motor; 25 …… Hollow shaft;
26 …… Ultra-small bubbles; 27 …… Partition plate; 28 …… Foam overflow outlet; 29…
… Tank; 30… Liquid level; 31… Small floating body; 32… Bar; 33 ……
Sensor; 34 ... Outlet; 35 ... Valve.

Claims (3)

[Claims] 1. A liquid tank for storing a liquid, and a hollow rotary shaft installed in the liquid tank, wherein a lower end of the hollow rotary shaft is provided with a vane along the axial direction and the vane up and down. A plurality of air holes are provided in a portion of the hollow rotary shaft sandwiched by the plate members, and air is sucked into the shaft by using a negative pressure generated by the rotation of the hollow shaft, A device for removing contaminants in liquid, characterized in that a bubble generating means for discharging ultrafine bubbles from the air holes in the horizontal direction with respect to the rotation axis is formed. 2. The partition wall plate for canceling the rotation of the liquid generated by the rotation of the hollow shaft is provided in the liquid tank, and the liquid surface position control means is attached to the liquid tank. The device for removing contaminants in the liquid described. 3. Ultra-fine bubbles in the liquid float up from the lower part to the upper part of the liquid tank, while the negative pressure generated by the rotation of the hollow shaft causes the liquid to flow down from the upper part to the lower part in the liquid tank. The device for removing contaminants from liquid according to claim 1.