JPS63294993A - Method for operating malodor preventive device for waste water tank for building or the like - Google Patents

Abstract

PURPOSE:To efficiently prevent rotting of the sewage in a waste water tank and generation of malodors with less electric power consumption by controlling the air quantity for aeration in such a manner that the dissolved oxygen or oxidation reduction potential in the tank attains a prescribed value. CONSTITUTION:The dissolved oxygen (DO) or oxidation reduction potential (ORP) of the sewage in the miscellaneous waste water tank is detected by a detector 11. This detected value is inputted to a control panel 12 which compares a set value and the detected value. The number of revolutions of a submersible motor 4 for aeration is lowered by a number of revolutions controller 13 to decrease the rate of aeration when the detected value exceeds the set value. The number of revolutions of the motor 4 is conversely returned to the original number to increase the rate of aeration when the detected value lowers below the set value. The air quantity for aeration is controlled by increasing and decreasing the number of revolutions of the motor 4 for aeration in such a manner, by which the dissolved oxygen or oxidation reduction potential is maintained nearly constant and the rotting of the sewage in the miscellaneous waste water tank 1 and the generation of the malodors are prevented.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a preferred method of operating an aeration device installed in a building drainage tank or a pump well at a pumping station for the purpose of preventing bad odors. be.

[Conventional technology and its problems]

Various types of waste water and human waste generated within a building are usually collected by gravity in a drainage tank installed underground, and then drained to a public sewerage facility by a drainage pump. However, conventional drainage tanks for buildings are simply equipped with a water tank, and the stagnant wastewater often undergoes anaerobic decomposition and generates a bad odor. For this reason, attempts have been made to install a blower to aerate and prevent anaerobic spoilage of the wastewater, but the method of operating the aeration equipment is not appropriate.
There were problems such as not being able to obtain a sufficient odor prevention effect, and even if the effect was obtained, the electricity cost was high.

An object of the present invention is to efficiently prevent the occurrence of bad odors by providing an appropriate operating method for an aeration device provided for supplying air into a drainage tank and mixing and agitating the inside of the tank.

[Means for solving problems]

By linking at least one of the devices for detecting dissolved oxygen or redox potential in a building drainage tank with an aeration device, and controlling the amount of aeration air so that the dissolved oxygen or redox potential is approximately constant, To prevent wastewater from decomposing and causing bad odors.

〔Example〕

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

In FIG. 1, reference numeral 1 denotes a gray water tank having a required volume installed in the basement of a building, and an aeration device 3 is installed at a desired position on the tank bottom 2 of this gray water tank 1. FIG. 2 is a detailed explanatory diagram of this aeration device, showing the submersible motor 4, stirring blade 5,
It consists of a draft tube 6 and an air blowing pipe 7. The submersible motor 4 is fixed to the bottom of the tank, and is integrally provided with a draft tube 6 whose upper end 6a is expanded in a trumpet shape and whose lower part 6b is bent in an L-shape along the bottom of the tank. A stirring blade 5 driven by the motor is provided inside the draft tube. An air blowing pipe 7 is provided in the draft tube 6 so that the air blowing lower a is inserted approximately at the center of rotation and within the inner diameter of the tip of the stirring blade.

The upper end of the air blowing pipe 7 is a vibrator having a diameter such that it is always open to the atmosphere even when the water level fluctuates, and a required amount of air is blown into the waste water.

In the apparatus configured as described above, when the submersible motor 4 is driven, the stirring blades 5 rotate to stir the wastewater in the tank. This also generates negative pressure in the waste water at the tip of this blade, and atmospheric air is sucked through the air blowing pipe 7, blown into the waste water from the air blowing lower a, and mixed with the waste water in the draft tube. and is pushed out toward the front of the draft tube.

The scum floating on the water surface is removed by the stirring blade 5.
The waste water flows into the draft tube together with the waste water, and is crushed by the stirring blade.

As described above, the aeration apparatus shown in this embodiment can not only agitate and aerate the inside of the drainage tank but also crush floating scum at the same time, but it may be an aeration apparatus that cannot crush scum. However, since scum is also one of the sources of bad odor, it is desirable to employ an aeration device with a scum crushing function or to provide a separate stirrer for scum crushing.

On the other hand, the drain pump 9 shown in FIG.
0N-OFF operation is performed in conjunction with 0, so that the water level is always in the range of high water level HWL and low water level LWLO. At this time, HWL and LWL are the suction port 6 of the trough tube.
If the distance from the upper end of a to the water surface is set to about 100 to 200 mm, floating scum on the water surface can be efficiently sucked in.

The aeration station having the above functions is operated in conjunction with the dissolved oxygen (Do) or oxidation-reduction potential (ORP) detector 11. That is, the measured value from the detector 11 is input to the control panel 12 having an arithmetic function, and the set value and the measured value are compared and determined.

Rotation speed control device 1 for adjusting the aeration amount of the c4 air device
3 is a submersible motor 4 for aeration based on a signal from the control panel 12.
The rotation speed is controlled. The set value of dissolved oxygen or redox potential, which is an indicator for control, is 3 mg /
For redox potential, +5 (around 1wV) is appropriate. For example, if you want to control the dissolved oxygen to be constant, the rotation speed of the underwater motor should be adjusted when the dissolved oxygen reaches 4 g/1. The amount of aeration is reduced by 1/2, and when the dissolved oxygen decreases to 3 mg/t, the rotation speed is returned to the original value and the amount of aeration is increased. By repeating this process, I1m is reduced. It is simplest to control the rotational speed in two stages, but it is also possible to reduce the rotational speed in several stages as dissolved oxygen or redox potential increases. However, in that case, the lower limit value of dissolved oxygen or redox potential must be set to maintain 0.5 mg/L for dissolved oxygen, or -100 mV or more for redox potential, or there will be no odor prevention effect. .This is because the amount of aeration is too small.
This is because when the inside of the tank becomes reduced, the activity of anaerobic microorganisms such as sulfate-reducing bacteria present in the wastewater becomes active, decomposing sulfate ions, etc., and producing hydrogen sulfide, which makes up most of the malodorous components.

The aeration system with the above configuration was installed in a building drainage tank of about 10 II + 3, and dissolved oxygen control operation was performed while controlling the amount of aeration air so that the DO value was 3 to 3.5 III g/L. The hydrogen sulfide inside was more than 5ppm before installation, but it was always 0.01ppm during the actual operation period.
We were able to maintain the concentration at a low level below.

FIG. 3 shows another embodiment of the present invention, in which the amount of aeration air is controlled by adjusting the opening degree of the electric valve 14 provided in the air blowing pipe 7, thereby preventing the occurrence of bad odors. To prevent. As in the case of FIG. 1, the opening degree of the electric valve 14 is determined by manually inputting the measured value of the dissolved oxygen or oxidation-reduction potential detector 11 to the control panel 12 having arithmetic functions, and comparing it with a previously manually inputted set value. When the measured value reaches the upper limit set value, the opening of the electric valve is reduced to reduce the aeration amount, and when the measured value decreases accordingly and reaches the lower limit set value, the electric valve is fully opened again. The set values for dissolved oxygen or redox potential are the same as in the previous example.

〔Effect of the invention〕

According to the present invention, an aeration device and a device for detecting at least one of dissolved oxygen and oxidation-reduction potential are provided in a building drainage tank, etc., and the driving rotation of the aeration device is adjusted so that the dissolved oxygen or the oxidation-reduction potential is approximately constant. By controlling the amount of aeration air while adjusting the number or pulp opening of the air blowing pipe,
To efficiently prevent wastewater in a drainage tank from decomposing and producing a bad odor with less power consumption.

[Brief explanation of drawings]

Figure 1 is a vertical cross-sectional view of a gray water tank installed underground equipped with the aeration system of the present invention, Figure 2 is a detailed explanatory diagram of the aeration system, and Figure 3 is a detailed illustration of the aeration system.
The figure shows different embodiments. 1 is a gray water tank, 2 is a tank bottom, 3 is an aeration device, 4 is a submersible motor, 5 is a stirring blade, 6 is a draft tube, 7 is an air blowing pipe, 9 is a drainage pump, 10 is a level switch, 11 is a detection 12 is a control panel, 13 is a rotation speed control unit. Figure 3

Claims (3)

[Claims] (1) In order to prevent the generation of bad odors from wastewater, at least one of dissolved oxygen or redox potential in the tank is detected in building drainage tanks equipped with aeration equipment, pump wells at pumping stations, etc. 1. A method for operating an odor prevention device for building wastewater, etc., comprising controlling the aeration air volume so that the dissolved oxygen or redox potential in the water reaches a predetermined value. (2) The method for operating a malodor prevention device in a building drainage tank or the like as set forth in claim 1, wherein the aeration air amount control means increases or decreases the driving rotation speed of the aeration device. (3) The method for operating an odor prevention device in a building drainage tank or the like as set forth in claim 1, wherein the aeration air amount control means adjusts the valve opening of the air suction pipe.