JP2006043542A - Operation control method of oxidation ditch and operation control device of oxidation ditch - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation control method of an oxidation ditch capable of enhancing the stabilization of the quality of water to be treated, and an operation control device of the oxidation ditch. <P>SOLUTION: In calculating the aeration time A<SB>n+1</SB>of the (n+1)-th operation cycle by setting the period from the start of aeration to the resumption of the next aeration to one operation cycle, the inflow amount (q) of water to be treated flowing in a tank is measured in the n-th just-before operation cycle to set the aeration time A<SB>n+1</SB>on the basis of the inflow amount (q) of the water to be treated. Accordingly, a suitable operation cycle reflecting the fluctuations in the inflow amount (q) of the water to be treated can be set. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an operation control method for an oxidation ditch and an operation control apparatus for an oxidation ditch.

2. Description of the Related Art Conventionally, an oxidation ditch that treats water to be treated such as sewage by alternately performing an aerobic process in which a nitrification reaction is performed by aeration and an oxygen-free process in which a denitrification reaction is performed by stirring is known. As an operation method of such an oxidation ditch, an integrated water discharge amount q _X that is the total amount of treated water per day is measured, for example, an average value of the integrated water discharge amount q _X in a period of about one week to one month is obtained, Based on this average value, an aeration time necessary for one day is set, the aeration time is fixed throughout the day, and for example, 30 minutes of aeration is performed 12 times a day for operation (for example, Patent Document 1).
Japanese Patent Laid-Open No. 11-683

  However, in the above operation method of the oxidation ditch, since the aeration time is fixed and does not sequentially correspond to the fluctuation of the inflow treated water amount, the fluctuation of the inflow treated water amount causes insufficient supply of oxygen and excessive supply. Stable processing was difficult.

  The present invention has been made in order to solve such problems, and it is possible to set an appropriate aeration time and stabilize the quality of the treated water. An object of the present invention is to provide a ditch operation control device.

  The operation control method of the oxidation ditch according to the present invention is an oxidation method in which an aerobic process in which nitrification reaction is performed by aeration and an oxygen-free process in which denitrification reaction is performed by stirring are alternately performed on water to be treated in a tank. This is a ditch operation control method, in which the amount of inflow treated water flowing into the tank within a predetermined time is measured from the start of aeration until the next resumption of aeration, and this inflow treated It is characterized by controlling the aeration time of the next operation cycle based on the amount of water.

  In addition, the operation controller for the oxidation ditch according to the present invention alternately performs an aerobic process in which nitrification reaction is performed by aeration and an oxygen-free process in which denitrification reaction is performed by stirring with respect to the water to be treated in the tank. An operation controller for the oxidation ditch, which measures the amount of inflow treated water flowing into the tank within a predetermined time period from the start of aeration until the next restart of aeration. And a control means for controlling the aeration time of the next operation cycle based on the inflow treated water amount.

  According to the oxidation ditch operation control method and the oxidation ditch operation control apparatus, the inflow treatment amount into the tank is measured in the immediately preceding operation cycle, and the aeration time is based on the inflow treatment water amount. Therefore, a change in the inflow treated water amount is reflected, and a suitable aeration time can be set.

  Here, the inflow treated water amount that flows into the tank in the operation cycle is measured, and this inflow treated water amount, the inflow treated water amount in the corresponding operation cycle on another day, and the inflow treated treatment in the next operation cycle. It is preferable to control the aeration time of the next operation cycle based on the fluctuation tendency with the amount of water. For example, the amount of effluent such as domestic effluent discharged from ordinary households varies according to human life time. This variation in the amount of drainage has a certain tendency by day (day and night), week (weekday and holiday), season (summer and winter), and the like. Therefore, by controlling based on the fluctuation tendency of the inflow treated water amount in the previous operation cycle and the inflow treated water amount in the next operation cycle, and by controlling based on the inflow treated water amount in the immediately preceding operation cycle, It is possible to set a suitable aeration time.

  As described above, according to the operation control method and the operation control device for the oxidation ditch according to the present invention, the fluctuation of the inflow treated water amount is reflected, and it is possible to set a suitable aeration time. Is possible.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an oxidation ditch operation control method and an operation control apparatus according to the present invention will be described with reference to the drawings. In the description of the drawings, the same or corresponding elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is a schematic configuration diagram of an oxidation ditch according to an embodiment of the present invention.

  The oxidation ditch 1 of the present embodiment biologically treats organic wastewater (treated water) (hereinafter referred to as “sewage”) such as domestic wastewater discharged from households, factory wastewater discharged from factories, and the like. It is a treatment facility that decomposes organic matter in wastewater in an aerobic state and removes nitrogen in an oxygen-free state.

  The oxidation ditch 1 generally includes a biological reaction tank (tank) 3 that includes an aeration stirring device 5 for aeration / stirring sewage to biologically treat the sewage, an inflow pump tank 2 that transfers sewage to the biological reaction tank 3, An integrated flow meter (flow rate measuring means) 4 for measuring the amount of inflow sewage flowing into the biological reaction tank 3 and a final sedimentation tank 6 installed at the rear stage of the biological reaction tank 3 are provided.

  The inflow pump tank 2 has an inflow side connected to a sewage supply pipe L1 that supplies sewage, and an outflow side connected to a sewage transfer pipe L2 that transfers sewage to the biological reaction tank 3, and the sewage transfer pipe L2 The integrated flow meter 4 is installed. The sewage flows into the biological reaction tank 3 via the sewage supply pipe L1, the inflow pump tank 2 and the sewage transfer pipe L2, and the amount of inflow sewage flowing into the biological reaction tank 3 is measured by the integrating flow meter 4. It is measured.

  The biological reaction tank 3 has an oval shape in plan view, and a partition wall 3a extending in the longitudinal direction is disposed at the center thereof, and a region around the partition wall 3a is formed as an endless circulation channel 7. In addition, a treated water transfer pipe L3 for sending treated water to the final sedimentation basin 6 is connected. Sewage is introduced into the circulating water channel 7 through the sewage transfer pipe L2, and purified water as treated water purified by biological treatment in the circulating water channel 7 from the circulating water channel 7 is passed through the treated water transfer pipe L3 to the final settling tank 6 Sent to.

  The aeration and agitation device 5 performs the above biological treatment, and is a rotatable impeller (not shown) and an impeller rotating motor that is a driving source for rotating the impeller and can be operated at a predetermined high speed / low speed ( (Not shown). The aeration and agitation device 5 is disposed in the vicinity of both ends of the partition wall 3a of the biological reaction tank 3, and the impeller is immersed in the sewage in the biological reaction tank 3. The impeller is rotated at a high speed by operating the motor at high speed, and the sewage in the biological reaction tank 3 is aerated and stirred, and the impeller is rotated at a low speed by operating at a low speed so that the sewage in the biological reaction tank 3 is oxygen-free. Stir.

  Moreover, in this embodiment, the operation control apparatus 10 which controls the driving | operation of the oxidation ditch 1 is comprised. The operation control device 10 includes the integrated flow meter 4, a timer 11 that measures time, and a control unit 12 that is connected to these and outputs a control signal to the impeller rotation motor of the aeration and agitation device 5. ing.

  The control means 12 is constituted by a CPU, and controls the rotational speed of the impeller rotating motor based on the amount of inflow sewage measured by the integrating flow meter 4 to control the high / low speed of the impeller.

  The operation control apparatus 10 further includes a storage unit 13 connected to the control unit 12 and a ROM 14 that stores the processing procedure in the form of a program. The storage means 13 is a time of one operation cycle (details will be described later), information set in advance regarding the rotational speed at the time of high-speed operation of the motor, speed at the time of low-speed operation, information on the aeration time, a predetermined arithmetic expression, etc. Remember.

FIG. 2 is a time chart showing an operation cycle of the oxidation ditch 1 shown in FIG. As described above, in the oxidation ditch 1, the aeration stirrer 5 is operated at a high speed to perform a nitrification reaction by aeration and stirring in the circulating water channel 7, and at a low speed to perform an oxygen-free operation in the circulating water channel 7. The oxygen-free process in which the denitrification reaction is performed by stirring is repeated alternately. Here, assuming that an aerobic process and the subsequent anaerobic process constitute one operation cycle, the duration T _n of the _nth operation cycle is the aerobic time C _n and the anaerobic time D _n . It can be expressed as a sum.

  Next, an operation control method for the oxidation ditch configured as described above will be described. FIG. 3 is a flowchart showing an operation control method of the oxidation ditch shown in FIG.

Here, the n-th operation cycle and the (n + 1) -th operation cycle immediately thereafter will be described as an example. First, sewage is supplied to the circulation channel 7 of the biological reaction tank 3 to form a predetermined circulation flow. In step S301, aeration stirring in the biological reaction tank 3 is started by controlling the motor for rotating the impeller of the aeration stirring device 5 and rotating the impeller at high speed. Then, the starts measuring the duration time T _n of the aeration period A _n and the operating cycle by the timer 11, starts measuring the inflow wastewater quantity q by integrating flowmeter 4.

In step S302, control is performed so that the impeller rotates at a predetermined high speed. Then, it is determined whether elapsed preset A _n time from the start aeration (time a) at step S303, if not elapsed, repeats the determination, at the time b~ time c, speed impeller Maintain rotation. Thereby, since the inside of the biological reaction tank 3 is maintained in an aerobic state, decomposition and nitrification of organic substances by microorganisms in the biological reaction tank 3 can be advanced.

In step S303, it is determined that the elapsed preset A _n time after aeration start (time c), the operation proceeds to step S304, controls the impeller rotating motor so impeller has a predetermined low-speed rotation . Then, it is determined whether elapsed predetermined T _n time from the start aeration (time a) at step S305, if not elapsed, it repeats the determination, at the time c~ time d, slow impeller Maintain rotation. Thereby, since the inside of the biological reaction tank 3 is maintained in an oxygen-free state, denitrification reaction can be advanced.

When the elapsed predetermined T _n times from the aeration starts (time d), the operation proceeds to step S306, and ends the measurement of the inflow wastewater quantity q by integrating flowmeter 4.

In subsequent step S307, an aeration time _{An + 1} for the next (n + 1) th operation cycle is set. Specifically, the ratio of the inflow sewage amount q to the planned inflow sewage amount Q, which is the equipment capacity of this oxidation ditch, is obtained, and the aeration time t ₀ necessary for appropriately processing the planned inflow sewage amount to this ratio To calculate the aeration time _{An + 1} for the next operation cycle.

  Subsequently, the process proceeds to step S308, the operation cycle counter is updated to n + 1, the process is terminated, the process returns to step S301, and the operation of the oxidation ditch is continued by starting the n + 1th operation cycle. To do.

  Thus, in the oxidation ditch operation control method and the oxidation ditch operation control apparatus of the present embodiment, the inflow sewage amount q into the biological reaction tank 3 is measured and the inflow sewage amount in the immediately preceding operation cycle. Since the aeration time is set based on q, the variation of the inflow sewage amount is reflected, and a suitable aeration time is set. As a result, the quality of treated water is stabilized.

  Further, since the aeration time is easily set by the control means 12, operation management is improved as compared with the case where the operation manager manually adjusts the aeration time. This is particularly effective for devices that have a large fluctuation in the amount of inflow sewage.

As mentioned above, although this invention was concretely demonstrated based on the embodiment, this invention is not limited to the said embodiment. For example, in the above embodiment, when calculating the aeration period A _{n + 1,} we obtain the ratio of the inflow wastewater quantity q against planned inflow wastewater quantity Q, over the aeration time t ₀ to the percentage aeration of the next operation cycle While calculating the time a _{n + 1,} obtains the ratio of the inflow wastewater quantity q against planned inflow wastewater quantity Q, the multiplied by the aeration time t ₀ in this ratio may be multiplied by the correction coefficient K, further correction value L may be added. The coefficient K and the correction value L are calculated, for example, based on the fluctuation tendency of the inflow sewage amount in the operation cycle during the same day the previous day and the inflow sewage amount in the next operation cycle. The correction value L may be a negative value. Moreover, you may calculate based on the amount of inflow sewage of the same day of the previous week instead of the previous day. Thus, it is possible to set a more suitable aeration time by correcting based on the fluctuation tendency of the amount of inflow sewage on another day.

  Moreover, in the said embodiment, although the inflow sewage amount is measured with the integrating | accumulating flow meter 4, you may calculate inflow sewage amount from the power consumption, operation time, etc. of the inflow pump tank 2 which transfers sewage. The amount of sewage flowing into the biological reaction tank 3 may be known.

  Moreover, in the said embodiment, although the inflow sewage amount is measured continuously through an operation cycle, you may calculate an inflow sewage amount based on the measurement of the predetermined time in an operation cycle.

  Moreover, in the said embodiment, although the shape of the biological reaction tank 3 is made into the ellipse shape, other shapes including a horseshoe shape and U shape may be sufficient.

It is a schematic block diagram of the oxidation ditch which concerns on embodiment of this invention. It is a time chart which shows the driving cycle of the oxidation ditch shown in FIG. It is a flowchart which shows the operation control method of the oxidation ditch shown in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Oxidation ditch, 3 ... Biological reaction tank (tank), 4 ... Integrated flow meter (flow rate measuring means), 5 ... Aeration stirring apparatus, 10 ... Operation control apparatus, 12 ... Control means.

Claims (3)

An oxidation ditch operation control method that alternately performs an aerobic process in which nitrification reaction is performed by aeration and an oxygen-free process in which denitrification reaction is performed by stirring with respect to water to be treated in a tank,
The period from the start of aeration until the next restart of aeration is taken as one operation cycle.
An operation control method for an oxidation ditch characterized by measuring an inflow treated water amount flowing into the tank within a predetermined time and controlling an aeration time of the next operation cycle based on the inflow treated water amount. Measure the amount of inflow treated water flowing into the tank during the operation cycle,
The aeration time of the next operation cycle is controlled based on the fluctuation tendency of the inflow treated water amount in the operation cycle corresponding to another day and the inflow treated water amount in the next operation cycle. The operation control method of the oxidation ditch of claim | item 1. An oxidation ditch operation control device that alternately performs an aerobic process in which nitrification reaction is performed by aeration and an oxygen-free process in which denitrification reaction is performed by stirring with respect to water to be treated in a tank,
The period from the start of aeration until the next restart of aeration is taken as one operation cycle.
A flow rate measuring means for measuring an inflow treated water amount flowing into the tank within a predetermined time;
And a control means for controlling the aeration time of the next operation cycle based on the inflow treated water amount.

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