JPS5842077Y2 - Biological “filtration” device - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a biological filtration device used when treating raw water using biological action, for example, removing BOD or nitrifying and filtering suspended solids.

As a biological filtration device, wastewater is introduced from the top of a treatment tank containing a biological filtration bed, and after aeration is performed above the filtration bed to dissolve oxygen in the wastewater, it is passed through the filtration bed to perform biological treatment and filtration. A device has been proposed to carry out the
No. 33666).

However, since this device uses air, it is not possible to maintain a high dissolved oxygen concentration, making it impossible to treat highly concentrated waste liquid.

In addition, oxygen dissolution efficiency was poor because aeration was performed above the filter bed.

In addition, some devices have been proposed that aerate from the bottom of the filter bed, but the air bubbles strongly agitate the inside of the filter bed, causing the inconvenience of dislodging microorganisms attached to the biological filter bed. There are limits to the improvement of catalytic oxidation.

This idea does not adversely affect the adhesion state of microorganisms.
The object of the present invention is to provide a biological filtration device that can promote biological effects such as oxidation or nitrification and can filter suspended substances.

The raw water to be treated is wastewater such as raw sewage to secondary treated water.

An embodiment of this invention will be described below with reference to the drawings.

The treatment tank indicated by reference numeral 1 in FIG. 1 is a closed type that houses a biological filter bed 2 inside, and the liquid inside forms a constant liquid level at a position higher than the upper surface of the biological filter bed 2. A trap 3 is provided as shown in FIG.

On the other hand, the raw water to be treated is first introduced into the dissolution tank 5 by the action of the pump 4.

Oxygen gas supplied through a valve 6 is introduced into the dissolution tank 5 under pressure by a compressor 7.
This oxygen gas is dissolved in the raw water in the dissolution tank 5.

Then, the raw water with dissolved oxygen is introduced into the dissolution tank 5 through the pipe 8 from the bottom thereof below the biological filter bed 2.

Preferably, suitable dispersion devices (not shown) are provided so that the introduced raw water is distributed approximately evenly over all parts of the lower surface of the biological filter bed 2.

The raw water containing a large amount of dissolved oxygen introduced into the treatment tank 1 is
In the process of rising in the treatment tank 1, it passes through the biological filter bed 2,
During this time, microorganisms attached to the biological filter bed 2 oxidize components in the raw water using dissolved oxygen.

The treated liquid is taken out as treated water from above the biological filtration bed via the trap 3, and sent to, for example, a rapid filtration device, where residual suspended matter in the treated water is separated.

If the pressure in the treatment tank 1 is maintained at the same level as the pressure in the dissolution tank 5, gasification of dissolved oxygen in the raw water will be slight, and therefore fewer bubbles will be generated in the dissolution tank 5. .

Therefore, the microorganisms attached to the biological filter bed will not be separated by the upward force of air bubbles.

Furthermore, since oxygen is consumed within the wave layer, even if the pressure in the treatment tank is low to some extent, the generation of bubbles is small.

The pressure inside the processing tank 1 is controlled by a valve 10 provided on a pipe 9,
It is determined by the opening degree of the valve 12 provided on the pipe 11.

In other words, a part of the gas present on the liquid surface in the treatment tank 1 (mainly consisting of carbon dioxide gas generated by the action of microorganisms and unconsumed oxygen) is discharged to the outside through the pipe 9. The other part is sent from the pipe 11 to the dissolution tank 5 together with the newly introduced oxygen gas, so the flow rate of the gas flowing through the pipes 9 and 11 is controlled by the valve 1.
By adjusting the opening degrees of 0 and 12, the pressure inside the processing tank 1 can be adjusted.

Further, the pressure may be adjusted by appropriate means such as repeating the operation of opening and closing the valve, or the pressure inside the tank may be detected to control the opening and closing of the valve or the degree of opening of the valve.

If the pressure inside treatment tank 1 is set to a sufficiently high value,
Gasification of dissolved oxygen in the treatment tank 1 is slight;
Therefore, the treated water taken out via the trap 3 contains a large amount of dissolved oxygen.

Since such treated water releases a large amount of oxygen gas when the pressure is depressurized within the separation device, remaining suspended solids can be floated and separated by the rise of bubbles.

Furthermore, if the pressure in the treatment tank 1 is set to a low value, many air bubbles will be generated in or near the biological filtration bed 2, so that effective stirring of raw water and floating separation of sludge due to the rise of air bubbles will be achieved. operations such as backwashing can be omitted.

In either case, compared to the case where air or high-purity oxygen gas is directly blown into the treatment tank 1, the raw water contains a large amount of dissolved oxygen, so the action of microorganisms within the biological filter bed 2 is is carried out actively and effective processing is realized.

For this reason, there is often no need to circulate the treated water.

Reference numeral 13 indicates a controller for adjusting the opening degrees of the valves 6.10 and 12 according to the carbon dioxide concentration or oxygen gas concentration in the gas taken out from the processing tank 1 via the pipe 11. The amount of exhaust and circulation is controlled to ensure effective use of oxygen gas.

Further, if necessary, in order to remove carbon dioxide from the gas taken out from the pipe 11, a device filled with NaOH or boric acid or another carbon dioxide removal device may be provided.

FIG. 2 shows a biological filtration device according to another embodiment of the invention.

In this device, raw water is introduced into a treatment tank 1 from above a biological filter bed 2, treated water is taken out from the bottom of the treatment tank 1, and a part of the treated water is supplied to a dissolution tank 5. It is the same as shown in Figure 1, except that
Therefore, the same parts as in FIG. 1 are indicated by the same reference numerals, and the explanation thereof will be omitted.

In this case as well, raw water introduced from above and treated water rich in dissolved oxygen introduced from below are supplied into the biological filter bed 2, so effective treatment is only possible. This is the same as in the case of FIG.

FIGS. 3 and 4 show other embodiments of this invention.

The device shown in FIG. 3 uses an ejector 14 instead of the dissolution tank 5 of the device shown in FIG. 1 to dissolve oxygen.

An ejector and a dissolution tank may be used together.

The one shown in FIG. 4 is a version of the one shown in FIG. 3 with a downward flow.

In addition, it is preferable to provide a backwash mechanism using treated water, air, etc., as in a general filtration device.

As described above, according to the biological filtration device of this invention, since oxygen gas is used, the dissolved oxygen concentration can be extremely high, and even highly concentrated raw water can be treated.Furthermore, the treatment tank is a closed type, and the exhaust gas is Exhaust and circulation can be controlled according to the components of
Furthermore, since the pressure inside the tank can be adjusted, the effective use of oxygen gas and the efficiency of processing can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a schematic longitudinal sectional view of a biological filtration device according to one embodiment of this invention, and FIGS. 2 to 4 are schematic longitudinal sectional views of biological filtration devices according to different embodiments of this invention. .

Claims (1)

[Scope of utility model registration request] Raw water is introduced into a treatment tank containing a biological filtration bed, the raw water is treated by the action of microorganisms attached to the biological filtration bed, and the obtained treated water is taken out,
Oxygen gas is dissolved in a part of the raw water or the treated water, and the liquid in which the oxygen gas is dissolved is introduced into a treatment tank with a closed structure, and the gas taken out from the upper part of the treatment tank is a means for discharging the gas, a means for returning this gas to the dissolving tank, a means for supplying oxygen gas to the dissolving tank, and a means for discharging the gas and dissolving the gas according to the oxygen concentration in the gas taken out from the processing tank. A biological filtration device characterized in that it is provided with a controller that determines the amount of circulation to a tank.