JPS63200898A - Automatic time controlling apparatus for intermittent aeration - Google Patents

Abstract

PURPOSE:To perform appropriate intermittent aeration automatically conforming to the increase and decrease of sedimentation velocity of sludge by sensing an interface of settled sludge independently at all of increase or decrease of level of surface of filthy water even if the level of the filthy water in a filthy water treating tank is increased or decreased every time at the beginning of aeration. CONSTITUTION:One of the timer T1 is set to give a signal for initiating aeration of the intermittent aeration, and another timer T2 is set to give a signal for initiating non-aeration of the intermittent aeration. And, the timer T2 is connected electrically to a driving circuit of the aeration apparatus 2 in such a manner that at least the measuring of time of the timer T2 is initiated by sensing effect of interface of a transmission type optical sensor S2. Further, a sensing section 5 of the transmission type optical sensor S2 is arranged to a float 3 moving vertically depending on vertical movement of water level l1 in a filthy water treating tank 1 so as to let light projecting surface 5a and light receiving surface 5b face oppositely to each other and concentrically with a specified distance interposing the liquid in the tank, and the buoyancy of the float 3 is set in such a manner that the sensing section 5 comes to an optional specified depth below the water level l1. Thus, the increase of transmitted light is sensed which is caused when an interface of settled sludge l2 passes a level where the sensing section 5 is located.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field to which the Invention Pertains] The present invention relates to an intermittent-1-air automatic time control device implemented in wastewater treatment for the purpose of high-rate nitrogen removal.

[Technical background of the invention and its problems]

When treating wastewater with intermittent aeration for the purpose of high-rate nitrogen removal, the ratio of nitrate nitrogen to ammonia nitrogen in the treated water in the same treated water tank is used as an index, and the aeration time in intermittent aeration and the time without aeration are used. A method of removing nitrogen in waste water at a high rate by increasing or decreasing the nitrogen content is known from Japanese Patent Publication No. 53435/1983 (inventor Kaoru SanPs and one other person).

In addition, when removing nitrogen using the above method, instead of performing the complicated measurement of ammonia nitrogen and nitrate nitrogen, the heating and non-aeration times are automatically adjusted using the sludge sedimentation rate, which is correlated with that, as an index. A method of decomposing organic matter and removing nitrogen at a high rate by doing so is also known from JP-A-30-172400 (initiated by Kaoru Mitsuhashi).

Using the above method, the aeration and non-aeration times are determined using the sedimentation rate of the sludge, and the time is incorporated into the electrical circuit.The time detected by the optical sensor is used as a regular electrical circuit timer, memory circuit, etc. for intermittent aeration processing. Although it is possible in principle to reproduce this, it is difficult in practice, and depending on the nature of the sludge sedimentation, it may be extremely difficult to use.

In other words, the settling speed of sludge is slow at first due to agglomeration of sludge flocs, but after the flocs grow, it gradually becomes faster, and eventually slows down again due to compaction of sludge. It is.

In addition, in the batch discharge type intermittent aeration control, the sludge is settled and discharged after the intermittent aeration ends, and interface detection is performed during this settling time.

and! As shown in 511, the light emitting surface 5'λ and the light receiving surface 5'
A transmissive optical sensor is used in which the sludge is placed concentrically facing each other at a predetermined interval, and the sensor is lowered from above the interface to detect the sludge settling interface by attenuation of the transmitted light between the emitting and receiving surfaces, or to detect the sludge settling interface at a certain depth. The technical idea of detecting the precipitation of the interface and the increase of the light by fixing the interface is already known. However, the transmission type optical sensor used in such a search method or fixed position method cannot immediately respond to changes in the water level in the sewage treatment JQ due to the inflow of sewage from multiple sources. The optical sensor sensing unit 5 is activated every time intermittent aeration starts.
The setting position of / has to be changed, and unattended management of batch discharge type intermittent aeration is difficult.

[Purpose of the invention]

The purpose of the present invention is to implement the wastewater treatment method described in Japanese Patent Application Laid-open No. 60-172400 at low cost using a simple device, and automatically respond to increases and decreases in the sludge settling rate regardless of increases and decreases in the water level in the sewage treatment tank. The object of the present invention is to provide an intermittent aeration device that can provide appropriate aeration/non-aeration time, and to enable unmanned management of the device.

[Summary of the invention]

In the automatic time control device for intermittent aeration according to the present invention, two timers are installed, one of which serves as an aeration start signal for intermittent aeration, and the other serves as a non-aeration start signal for intermittent aeration. An automatic time control device for intermittent aeration electrically connected to a drive circuit of an aeration device so that at least a non-aeration start timer among the timers is started by an interface detection action of a transmission type optical sensor. A sensing part of a projection type optical sensor is arranged on a float that rises and falls according to the rise and fall of the water surface in the sewage treatment tank so that a light emitting surface and a light receiving surface are concentrically opposed to each other at a predetermined interval with the liquid in the tank interposed therebetween. The buoyancy of the float is set so that the sensing part is located at an arbitrary predetermined depth on the water surface hinge ζ in the tank, and the sludge settling interface reaches the location where the optical sensor sensing part is installed. The device is configured to detect an increase in transmitted light.

In intermittent aeration treatment, biological treatment and precipitate discharge are carried out in the same treatment tank in batches (this is done by an all-day timer, with a down time for sludge sedimentation and discharge of supernatant water, and a treatment time for intermittent aeration treatment). In the present invention, when the intermittent aeration process is finished, a timer signal is input to start timing (after a certain period of time if two optical sensors are used).

In order to repeat aeration and non-aeration many times within a fixed wastewater treatment time and to make the sedimentation rate of sludge sensitively reflect the aeration conditions, it is desirable to use two transmission type optical sensors.

[Example: 1] In Fig. 2 [A], 1 is a sewage treatment (box), 2 is an aeration device installed in the sewage treatment tank 1, and 3 is a gap in the sewage treatment tank 1 through which the tank liquid flows. Sewage treatment t! with twin-shaped floats formed vertically facing each other with g apart.
! It moves up and down along the lifting guide 4 according to the lifting and lowering of the water surface j1 in the tank. Sl and S2 are transmissive optical sensors, Tl is a timer that starts measuring time by the interface detection action of the first optical sensor s1, and T2 is a timer that starts measuring time by the interface detection action of the optical sensor S2 of 9J2. In @3 reasons, 5 is a sensing part of an optical sensor, and is arranged on the float 3 so that the light emitting surface 5z and the light receiving surface 5b face each other concentrically at a predetermined interval through the liquid in the tank in the gap g. has been done. And a weight 6 for adjustment is installed inside or outside the float 3.
The buoyancy of the float 3 is set so that the sensing parts 5 of the optical sensors Sl and S are positioned at an arbitrary predetermined depth below the surface of the liquid in the tank. The sensing section 5 of -Sl is set to a relatively shallow water depth, and the sensing section 5 of the second photosensor-S2 is set to an appropriate water depth deeper than the sensing section 5 of the first photosensor-Sl. It is.

Two timers T1. 'r is set to the total time of one aeration and one non-aeration period of intermittent aeration. When the settling interface 12 of the sludge passes past the sensing part 5 of the first optical sensor-S1 after the start of settling and light passes through it, the timer T1 of Jll starts timing. The sludge settling interface 12 is the second optical sensor.
When the light passes through the sensing section 5 of S2 and is transmitted, the second timer T2 starts timing. The time difference between the first timer T and the second timer T2 is the time it takes for sludge to pass between the set water depth of the first optical sensor S1 and the set water depth of the second optical sensor S2. , which is a time that reflects the sedimentation properties of sludge. Therefore, if the first timer Tl is used as the aeration start signal and the second timer T2 is used as the aeration stop signal, the aeration and non-aeration times will vary depending on the sedimentation rate of the sludge, and will still be within a certain processing time. Since this aeration/non-aeration process can be repeated many times in alternation, it is possible to obtain an appropriate aeration/non-aeration time that responds sharply to increases and decreases in the sedimentation rate.

That is, when discharging supernatant water and starting intermittent aeration treatment again after the pause time ends, the timer T of *i starts counting from the beginning because the set time has already ended, and each time Sends an aeration start signal. Second timer T
Since time measurement was interrupted in case 2, time measurement will be continued from the halfway point when reprocessing begins. This is the aeration stop signal, that is, the non-aeration start signal. Since the first timer Tl and the second timer T2 are set to the same time, T2 will issue a signal later than T1 by the sludge settling time until the next downtime.

According to experiments, when the first optical sensor S1 is set at a water depth of 21 and the optical sensor S2 of MS 2 is set at a water depth of 10 eIIA in an aquarium with a water volume of approximately 501, the first The optical sensor-Sl of 6 receives the light, and
After 5 minutes, the second optical sensor S2 received light.

゛First timer T, ,! :The time difference with the second timer T was 35 minutes, and when the aeration equipment was operated for a total of 60 minutes of aeration and non-aeration, the ratio of nitrate nitrogen to ammonia nitrogen in the effluent was 4.9. Ta. When operation was continued under the same conditions, the aeration time varied between 20 and 50 minutes.

[Example = 2] When the initial sedimentation of sludge is relatively large and the time and sedimentation depth are almost proportional, the first optical sensor is omitted and the sedimentation start signal is used as shown in Fig. 2 (CB). Next, the timer can start counting the first timer T1 after a certain period of time. Light is emitted from the light emitting surface 52 of the source sensor S2, and when the sludge settles and passes the set water depth of the sensing section 5, the light is received by the light receiving surface 5b, and this signal is input to the second timer T2 to measure time. Start sle. When timer T1 of WJl exceeds the set time, both timers T, , 'r, are interrupted. Thereafter, intermittent aeration was performed again in the same manner as in Example 1.

According to experiments, in an aquarium with a water volume of about 401, the sensing part 5 of the original sensor S2 was set to a water volume of about 8 cIL, and the first timer T1 started timing with a stirring signal before the start of sedimentation.

The original sensor S2 received light in about 20 minutes and started timing. After stirring for 2 minutes, the time difference between the first timer T1 and the second timer T2 became 22 minutes. Non-aeration time 4
When 8 minutes were added for a total time of 70, the ratio of nitrate nitrogen to ammonia nitrogen in the flowing water was 2.2.
Met. When I continued to operate under the same conditions, the aeration time ranged from 15 minutes to 45 minutes, which was quite different.

[Efficacy of invention]

According to the present invention, the wastewater treatment method described in JP-A-17-17G400 can be implemented at low cost using a simple device, and the water level in the sewage treatment tank increases and decreases each time aeration starts. It also accurately detects the sludge settling interface regardless of changes in the water level, immediately responds to changes in the sludge settling rate, and then automatically repeats intermittent aeration with appropriate aeration/non-aeration times. This has the advantage of enabling unattended management of batch discharge type intermittent aeration.

[Brief explanation of the drawing]

1r: IJ is a time chart of intermittent aeration performed by the control device of the present invention, FIG. Main part vertical v of the float for detecting the sludge settling interface in the invention control device
4 is a plan view of the same float, and FIG. 5 is a side view of a sensing portion in a known transmission type optical sensor. 1...Sewage treatment tank, 2...Aeration device,
8...Float, 5...Sensing section, 5λ
......Light emitting surface, 5b... Light receiving surface, tl.
...Water surface, t2 ...Sludge settling interface, S2
......Transmissive optical sensor, T1...Aeration start timer, 72 a** ***Non-1@Aeration start timer. Patent applicant: Shimami Seisakusho Co., Ltd.

Claims (1)

[Claims] Two timers (T_1) (T_2) are installed, one of which serves as the aeration start signal for intermittent aeration, and the other serves as the non-aeration start signal for intermittent aeration, and both timers (T_1) (T_2) At least the non-aeration start timer (T_2) starts timing when the transmissive optical sensor (S_
In the automatic time control device for intermittent aeration, which is electrically connected to the drive circuit of the aeration device (2), the water surface in the sewage treatment tank (1) is controlled by the interface detection function of 2). Float (3) that rises and falls according to the rise and fall of (l_1)
The sensing part (5) of the projection type optical sensor (S_2) is arranged so that the light emitting surface (5a) and the light receiving surface (5b) are concentrically opposed to each other at a predetermined interval through the liquid in the tank, In addition, the buoyancy of the float (3) is set so that the sensing part (5) is located at an arbitrary predetermined depth below the water surface (l_1) in the tank, and the sludge settling interface (l_2) is located at the optical sensor sensing part (5). an automatic time control device for intermittent aeration configured to detect an increase in transmitted light caused by passing through a disposed location of the intermittent aeration;