JPH0478359B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aeration agitation device for biologically treating sewage or industrial waste water.

When treating wastewater containing organic matter, such as sewage or industrial wastewater, it is common to aerate the wastewater and perform aerobic fermentation treatment.

As a self-priming aeration agitation device suitable for this purpose, Japanese Patent Publication No. 44400/1983
The one described in Publication No. 500281 is publicly known. In each case, these aeration stirring devices have a gas flow path leading to the axial outlet opening through a hollow shaft, so they have a structure that has an opening for intake at the top of the hollow shaft and communicates with the atmosphere. It's getting old.

However, in recent years, so-called eutrophication of water has become a problem, and there is a demand for adding nitrification and denitrification to biological treatment.

Therefore, it has become desirable to provide a self-priming type aeration stirring device with a function that performs only the stirring function without producing an aeration function in addition to the normal aeration stirring function, and to use these functions properly.

The present invention was made in view of this, and combines anaerobic stirring function and aerobic stirring (stirring with aeration) function into one.
The purpose is to easily combine this into one aeration and stirring device.

For this reason, in the present invention, the opening provided in the rotating hollow shaft is surrounded by a box, the gas passage is provided in this box, and the gas passage is fixed, and the gas passage fixed in this way is It is characterized by having a valve for ventilation and shutoff.

Embodiments of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, a stirring device 1 is provided with a hollow shaft 3 directly connected to a motor 2, these are housed in a box 4, and a propeller 5 for stirring is attached to the tip of the hollow shaft 3. . The hollow hole of the hollow shaft 3 has an opening 6 at the axial outlet of the propeller 5 tip. Further, the hollow shaft 3 is provided with an opening 7 that opens into the box 4 and communicates with the hollow hole at a position that is always above the water surface, and a valve 9 is provided in the gas passage 8 provided in the box 4. An inverter 10 is connected to the propeller rotation motor 2 as a rotation control mechanism. Therefore, in such a stirring device, when the propeller 5 is rotated by the motor 2 when the valve 9 is open, a water flow is generated in the axial direction of the hollow shaft 3 in the direction of the arrow A shown in FIG. A low pressure section (negative pressure) is formed at the tip of the hollow shaft 3, and gas or air is mixed into the water flow due to this low pressure. Therefore, an aeration function can be obtained at the same time as stirring. Furthermore, when the valve 9 is closed, air is blocked from entering the box 4, so no gas is mixed into the water flow, and only the stirring function is provided.

Although the box 4 includes and encloses the motor 2 in the above embodiment, it goes without saying that the opening 7 may be covered to block the outside air from the purpose and idea of the present invention.

According to the present invention described above, there is an advantage that a conventionally known self-priming type aeration stirring device can be made into a stirring device that can be used for either aerobic or anaerobic operation by simply modifying the structure.

An example of a water treatment apparatus including nitrification and denitrification using the apparatus of the present invention will be described below.

An example of a water treatment device equipped with the above-mentioned aeration stirring device 1 is shown in FIGS. 2 and 3. In the figure, the water treatment device 11 is an annular aeration tank 12.
One or more mounts 13 are attached to the mounts 13, and the aeration stirring device 1 is mounted or suspended on the mounts 13. In addition, a current meter 14 and a dissolved oxygen meter 1 are provided in the aeration tank 12.
5 will be provided. For measurement purposes, these instruments are preferably installed near the bottom of the tank where the flow rate is slowest and the dissolved oxygen concentration is lowest. Further, the aeration tank 12 is provided with a wastewater inlet 16 near the installation part of the aeration stirring device 1, and a treated water outlet 17 is provided slightly upstream thereof.

Next, in the embodiment configured as described above, treatment of waste water will be explained.

Sewage is introduced into the aeration tank 12 through the inlet 16.

The introduction timing is selected to be when the valve 9 is closed for reasons described later. Also, at the beginning of use, a small amount of activated sludge is added if necessary. After storing the wastewater in the tank 12, the aeration stirring device 1 is operated. Due to the operation of the aeration stirring device 1, a circulation flow shown by an arrow B is generated in the aeration tank 12. Also, valve 9
By opening it, gas is blown into the waste water. This ferments and decomposes organic matter in the wastewater. During this time, the circulation flow rate is measured using the current meter 14 to monitor whether the desired stirring is being performed. If the stirring is insufficient or excessive, the rotation speed of the aeration stirring device 1 is increased or decreased. In a normal activated sludge method or a similar method, the bottom flow velocity required to prevent sludge from settling at the bottom is 10 cm/sec or more.

On the other hand, when the dissolved oxygen concentration of the wastewater is detected by the dissolved oxygen meter 15 and the value reaches a predetermined value,
Open and close valve 9. This operating method will be explained according to the control flow sheet shown in FIG. 4. First, the aeration device is started with the valve 9 closed. As a result of stirring the wastewater, fermentation by aerobic bacteria progresses and the dissolved oxygen concentration rapidly decreases due to oxygen consumption. When the dissolved oxygen concentration is equal to or less than a predetermined lower limit set value (e.g. 0.3 mg/), a timer is activated;
Anaerobic digestion is performed for a preset time, and after this time has elapsed (usually 5 to 10 minutes, although the set time varies depending on the capacity of the tank, the type of sewage, etc.), the valve 9 is opened and aerobic digestion is performed. Then, when the dissolved oxygen concentration is equal to or greater than a predetermined lower limit set value (for example, 1.5 mg/), the valve is closed again and the aforementioned anaerobic digestion is performed.

Nitrification and denitrification using the above operating method is performed as follows. First, in an aerobic atmosphere, organic nitrogen (urine, protein, etc.) in wastewater becomes activated sludge through the activity of BOD bacteria, and NH ₄ ⁺ is released. This is then nitrified by nitrite bacteria and then nitrate bacteria. This can be expressed as the following formula.

NH ₄ ⁺ +3/ _2O 2Nitrite bacteria――――――→ NO ₂ +2H ⁺ +H ₂ O NO ₂ ^- +1/2O _2Nitrate bacteria――――→ NO ₃ ^-Next , the nitrified wastewater becomes dissolved oxygen When the concentration is set to 0 or close to 0 and an organic carbon source (sewage, methanol, etc.) is added to this, denitrifying bacteria in an anaerobic atmosphere becomes active, and NO ₃ ^- +5CH ₃ OH denitrifying bacteria---→ 3N ₂ ＋7H ₂ O＋5CO ₂ ＋
Denitrification occurs as 6OH ^- .

According to the above embodiment, the dissolved oxygen concentration in the aeration tank is measured, and the valve 9 provided in the box 4 is opened and closed to alternately obtain an aerobic atmosphere and an anaerobic atmosphere, thereby performing nitrification while performing the necessary stirring. denitrification can be performed.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the aeration and stirring device of the present invention, Figs. 2 to 4 show application examples of water treatment equipment using the device of the present invention, and Fig. 2 is a plan view thereof;
FIG. 3 is a longitudinal sectional view of the same, and FIG. 4 is a flow chart. DESCRIPTION OF SYMBOLS 1... Aeration stirring device, 2 Motor, 3... Hollow shaft, 4... Box, 5... Propeller, 6... Axial outlet opening, 7... Opening, 8... Gas passage, 9...
Valve, 10... Inverter, 11... Water treatment device,
12... Aeration tank, 13... Frame, 14... Velocity meter, 15... Dissolved oxygen meter, 16... Inlet, 17
……Vent.

Claims (1)

[Claims] 1 having a hollow shaft with an axial outlet opening at its free end, carrying a propeller at the free end of said hollow shaft;
Its free end is immersed in the liquid in the aeration tank, and the rotation of the propeller creates a flow that advances in the axial direction of the hollow shaft, which agitates the liquid and at the same time pushes the axial outlet opening of the hollow shaft. In a self-priming aeration agitation device that forms a low-pressure part and sucks gas into the liquid, an opening that is provided at the upper part of the hollow shaft of the aeration agitation device and forms an inlet of a gas flow path that leads to an axial outlet opening. What is claimed is: 1. An aeration agitation device characterized in that the aeration and agitation device is surrounded by a box to isolate it from the outside, a gas passage is provided in the box, and a valve is provided in the gas passage.