JPS61114795A - Apparatus for controlling concentration of dissolved oxygen - Google Patents

Abstract

PURPOSE:To properly control the amount of a wind, by correcting the dissolved oxygen concn. control signal based on the signal of the dissolved oxygen densitometer arranged only to one system corresponding to the ratijo of the amounts of sewages flowed into systems. CONSTITUTION:The suspended matter in sewage is sedimented under its own wt. in a sedimentation basin 3 and removed while withdrawn through a sludge withdrawal valve 6 by an initial sedimented sludge withdrawal pump 7. Subsequently, sewage is mixed with activated sludge to be flowed into a final sedimentation basin 5 while receives aeration. A dissolved oxygen densitometer 16 is provided to the aeration tank of one system and the output signal from said densitometer 16 is inputted to a dissolved oxygen concn. regulator 14 as a feedback signal. The regulator 14 performs the comparing operation of a preset dissolved oxygen concn. objective value and the feedback signal to output the control signal MV1 corresponding to the difference between both of them. By the magnitude of this output, the opening degree of the wind amount regulator is controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a dissolved oxygen concentration control device in a plurality of lines of sewage treatment equipment.

[Technical background of the invention and its problems]

In the sewage purification process of sewage treatment plants, it is important to maintain the dissolved oxygen concentration in the aeration tank at a certain value C in order to stabilize biological reactions in the aeration tank.

Therefore, the dissolved oxygen concentration is kept constant. At that time, it is necessary to install a dissolved oxygen meter to detect the dissolved oxygen concentration in the aeration tank, but as the number of water treatment lines increases, it is necessary to install three dissolved oxygen concentration meters in total. arise.

If a dissolved oxygen meter is installed in only one series F, and the air flow rate of multiple series is controlled based on the signal C of one dissolved oxygen meter, sewage will flow into the first settling tank of multiple series. Due to the unevenness of the amount of inflowing sewage to each series due to the difference in the channel resistance through which the sewage flows, the dissolved oxygen concentration values of each series are not the same, and the dissolved oxygen concentration (in series with large inflow water) value decreases.

On the other hand, in a series where the inflow water ILp is small, the dissolved oxygen concentration value becomes too high, which adversely affects wastewater purification.

However, it is extremely uneconomical to install dissolved oxygen concentration monitors in all lines, and problems such as increased maintenance work for dissolved oxygen concentration meters occur.

[Purpose of the invention]

The present invention has solved this problem. An object of the present invention is to provide a dissolved oxygen concentration side cannon device that controls the dissolved oxygen concentration of each series in the same way.

[Summary of the invention]

The present invention has a sewage treatment facility consisting of a plurality of series of initial settling tanks, aeration tanks, and final settling tanks, which has a timer circuit, a sludge concentration meter, and an alarm setting device, and starts sludge extraction from the first settling tank from timer C. Based on the sludge extraction amount data from the initial settling sludge extraction control means and the initial settling sludge extraction flow rate measuring device, which stop sludge extraction when the concentration of the extracted sludge has decreased.

Calculate the distribution ratio of inflow sewage to each series, and from the results,
By correcting the output of dissolved oxygen 11 degree control based on the dissolved oxygen concentration meter signal installed only in a certain series for each series, and controlling the air flow rate of each series, the dissolved oxygen concentration of each series can be adjusted. This is a dissolved oxygen concentration control device that maintains a value of -C;

[Embodiments of the invention]

Next is an example of the present invention! Let me explain about two things.

In the drawing, sewage flows into a settling tank IC and is first pumped to a settling tank 3 by a sewage pump 2. First, suspended matter in the sewage settles under its own weight in the settling tank 3, and the sludge withdrawal valve 6. The sludge is pulled out and removed by the initial settling sludge extraction pump 7. The sewage t that has passed through the initial settling tank 3 is mixed with the activated sludge returned from the final settling tank 5 through aeration Pa4.

After being aerated with air blown by blower 8,
It flows into the final settling tank 5. In the final settling tank 5, the organic matter decomposed by the biological reaction in the aeration tank 4 coagulates and settles, completing the sewage purification.

The sewage pumped up by the sewage pump 2 flows into the first settling tank 3C of each series. The sludge is first removed from the settling tank 3 at regular intervals according to a command from the timer circuit. That is, when a sludge drawing command is output from the timer circuit 12, the sludge drawing pump 7 is operated and the sludge drawing valves 6 of each series are opened.

While the sludge is being extracted, the sludge concentration is measured by the sludge concentration meter 9, and when the sludge concentration decreases to a set value, an alarm contact or alarm setting device 13 outputs an output. This alarm contact signal is manually input to the timer circuit 12 as a command to stop sludge extraction, and at this point, sludge extraction is stopped. During the sludge drawing R during this period, the flow rate is measured by the flow meter 10C and input to the calculation device 17. It can be considered that the sludge extraction tit measured here is proportional to the sewage @I flowing into each series.

Therefore, the sludge pulling rats of each series are X, , X, respectively.
, .

......If Xn is the ratio of @indigo flowing into each series to the total number of indigo flows, it is expressed by the following formula.

The arithmetic unit 13 performs the above calculation to calculate the proportion of the amount of wastewater flowing into each series.

On the other hand, a dissolved oxygen concentration 16 is installed in the I-series aeration tank, and the dissolved oxygen concentration meter output signal is inputted as a feedback signal to the dissolved oxygen concentration controller 14.

The dissolved oxygen concentration controller 14 compares and calculates a preset dissolved oxygen concentration target value with this feedback signal, and outputs a control signal MV corresponding to the difference. Based on the magnitude C of this output, the function of the air volume control valve 11 is controlled, the air blowing dragon to the aeration tank 4 is controlled, and the dissolved oxygen concentration value is operated to reach the target value. In this way, in one series, dissolved oxygen control is performed once based on the feedback value C of the dissolved oxygen concentration meter 16. For the other series ζ, control is performed as follows.

A signal corresponding to the ratio of the amount of inflowing sewage to each series calculated by the arithmetic unit 117C and a control signal MY of the dissolved oxygen concentration controller 14 are inputted to the arithmetic and control unit 151.

The arithmetic and control unit 115 corrects this control signal MY1 according to the ratio of the amount of wastewater flowing into each series, and determines control signals MT/, . . . MYn to the air volume control valves of each series.

That is, MY, =-3-LxMV! , , 2 series The control signal to each series calculated from the above equation 1U is output from the arithmetic and control unit 115, and the opening degree of the air volume control valve of each series is controlled.

〔Effect of the invention〕

In this way, the present invention (= means that in a water treatment facility with multiple lines, the dissolved oxygen concentration meter signal (;
By correcting the dissolved oxygen concentration control signal based on the ratio C: of the amount of sewage flowing into each series, the air volume of each series can be appropriately sub-controlled.

[Brief explanation of drawings]

The drawing is a configuration diagram of a dissolved oxygen concentration control device showing an embodiment of the present invention. l...Sand basin 2...Sewage pump 3...
- Initial settling tank 4... Aeration tank 5... Final settling tank 6... Sludge withdrawal valve 7... Initial settling sludge withdrawal pump 8... Blower 9... Sludge a meter 10.
...Flow, 1 total 11...Wind I'l 1 section valve 12.
... Timer circuit 13 ... Alarm setting device 14 ... Dissolved oxygen concentration controller 15 ... Arithmetic control device 16 ... Dissolved oxygen a meter 17 ... Arithmetic device agent Patent attorney Noriyuki Chika (1 other person)

Claims (1)

[Claims] In a multi-line sewage treatment process consisting of an initial settling tank, an aeration tank, and a final settling tank that are installed in parallel with each other, an initial settling sludge extraction pump that pulls out the sludge that has settled in the initial settling tank, and a a sludge withdrawal valve connected to a pipe between the sludge withdrawal pump and the first settling tank; a sludge concentration meter connected in series with the first settling tank sludge withdrawal pump to measure the concentration of the drawn sludge; and the sludge concentration meter. a sludge flow meter that measures the flow rate of sludge passing through the meter; a timer circuit that controls the start of operation of the initial settling sludge extraction pump for each series;
an alarm setting device that alarms for each series a decrease in the concentration signal detected by the sludge concentration meter; a sludge flow rate signal for each series output from the sludge flow meter; and a sludge flow signal for each series output from the sludge concentration meter; A computing device that calculates the inflow sewage volume distribution ratio for each series from the sludge concentration signal, a blower that sends air to the aeration tank for aeration, and a blower provided for each series to adjust the amount of aeration air sent out by the blower. air volume control valve,
Receiving signals from a dissolved oxygen concentration meter and a dissolved oxygen concentration meter that measure the dissolved oxygen concentration in the aeration tank of the series, the opening degree of the air volume control valve is controlled to maintain the dissolved oxygen concentration of the series at a set value. It is equipped with a dissolved oxygen concentration controller and an arithmetic control device that corrects and outputs a control signal to the air volume control valves of other series with respect to the output signal of the dissolved oxygen concentration controller based on the calculation result of the arithmetic device. Dissolved oxygen concentration control device.