JP4464851B2 - Operation control method for aeration apparatus - Google Patents

Description

  The present invention allows organic sewage such as sewage in a sewage treatment facility to be nitrified and denitrified by the action of activated sludge microorganisms using the aeration equipment, for example, operation control of aeration equipment such as oxidation method, anaerobic aerobic method It is about the method.

  In the activated sludge treatment method for sewage that alternately turns into anaerobic and aerobic conditions by intermittent aeration, the fall of dissolved oxygen (hereinafter referred to as DO) is collected in time series immediately after the aeration apparatus is stopped. The sludge respiration rate indicating the slope of the aeration is measured for each aeration cycle, the aeration interval time is automatically set according to the measured sludge respiration rate, and the aerobicity exceeds the DO value at which the nitrification reaction proceeds in the aeration interval time The aeration is automatically set according to the respiration rate of sludge, which measures the ratio of aerobic / anaerobic time to the anaerobic time near 0 when the denitrification reaction proceeds in the time and the supply of oxygen is stopped. A method of controlling the aeration apparatus stop time by predicting from the respiration rate of the sludge measured in the previous cycle so that the aerobic / anaerobic time ratio becomes the set value at the interval time is known. (E.g., see Patent Document 1). However, in this method, the measured value of the sludge respiration rate indicating the DO descent slope is predicted from the sludge respiration rate measured in the previous cycle on the assumption that there is almost no change in the previous and next cycles. For example, in the early morning when a small amount of used water flows in at night, and in the early morning when human activity starts and a large amount of used water flows in, the load of the OD in the tank is greater than the amount of sewage flowing in. Even if is clearly rising, the morning aeration cycle is determined based on the tendency obtained from the aeration cycle during the night when the load of the previous measurement was low. Proper nitrification and denitrification treatment is not performed.

  In addition, as another known example, in a water treatment facility in which an aerator is intermittently operated by a dissolved oxygen meter installed in an aeration tank, after the start of aeration, the time until reaching the boundary dissolved oxygen value between anaerobic and aerobic, anaerobic and When dissolved oxygen rises from the aerobic boundary dissolved oxygen value and reaches the preset upper limit dissolved oxygen value, aeration is stopped, and then the time until the anaerobic / aerobic boundary dissolved oxygen value is measured again. The anaerobic time is calculated based on the measured time, and one cycle of operation is performed so that aeration is resumed after the anaerobic time has elapsed (see, for example, Patent Document 2). However, in this method, the inflow sewage load is determined from the aeration status (time) in this cycle and the anaerobic time after aeration is calculated, so there is no time lag, but the upper limit dissolved oxygen value and aerobic・ There are many optional settings such as the ratio of anaerobic time, and the ratio of aerobic / anaerobic time may be 1: 1 for the rated sludge load, but nitrification / denitrification reactions may be performed at low loads such as in the beginning of service. Considering this, this ratio needs to be adjusted so that “aerobic time <anaerobic time”, and the setting must be changed frequently.

Japanese Patent Laid-Open No. 11-128976 (Abstract, 0022, FIG. 3) JP-A-7-136682 (Summary, Fig. 2)

  The problem to be solved is that, in the activated sludge treatment method in which aeration is intermittently performed, a time lag of the aeration cycle as in the above-mentioned Patent Document 1 is caused even with a large load variation due to a change in the amount of inflow sewage. It does not occur, and it does not require frequent setting changes at a low load such as the initial stage of service as in the above-mentioned Patent Document 2, and sufficient nitrification reaction is performed without supplying more air than necessary during an aerobic time period. And a method for controlling the operation of an aeration facility in a sewage treatment facility capable of promoting an appropriate denitrification reaction in an anaerobic time zone.

In the present invention, in the operation control method of the aeration apparatus in which the aerobic treatment and the anaerobic treatment are alternately performed in time series by continuously stirring and intermittently aeration of the sewage in the aeration tank, air supply by the aeration apparatus The dissolved oxygen change value in the tank is detected by a dissolved oxygen sensor attached to the tank, the detection signal is processed by the control device, and a signal is transmitted to the inverter that controls the rotation of the aeration device. Of the aerobic treatment based on the sampling time, which is the detection cycle of the dissolved oxygen value, the dissolved oxygen index value for calculating the inflow load of sewage, and the dissolved oxygen target value for ensuring a stable nitrification reaction In this case, the aeration apparatus is rotated at a constant speed until the dissolved oxygen index value is reached after the start of aeration, and the anaerobic treatment of the next process is performed based on the inflow load amount calculated from the arrival time to the dissolved oxygen index value. It takes to calculate the anaerobic time aeration stop, further, in order to reach quickly the dissolved oxygen target value from the arrival of the dissolved oxygen index value, determining whether the dissolved oxygen value of current is increased for each of the sampling time In the case of non-increase, a command to increase the frequency of the inverter is issued, and in the case where the determination is increased, a command to continue the frequency operation state at that time is issued to control the operation of the aeration apparatus, and the dissolved oxygen target value is set. When reaching the predetermined dissolved oxygen constant control operation time, the aeration apparatus is controlled at a variable speed so that the dissolved oxygen value in the aeration tank is maintained at the dissolved oxygen target value state. When the oxygen constant control operation time has elapsed and the aerobic device is stopped at the calculated anaerobic time, the dissolved oxygen value decreases and the anaerobic treatment is continued. To resume started aerobic treatment aeration in air time, properly and most important feature that causes the intermittent operation control of the aeration device to repeat alternately aerobic treatment and anaerobic treatment.

  According to the present invention, the dissolved oxygen value is detected finely by the dissolved oxygen sensor installed in the tank every preset sampling time, and the inflow load amount is calculated and recognized from the rising aeration status in the current cycle, and the dissolved oxygen in the tank is Since the aerating device operation control and aeration cycle and anaerobic time are quickly and automatically adjusted to stop aeration from a stable state with the target value kept constant, early morning when less used water flows in at night, Even if the load fluctuation difference of the inflowing sewage after 8:00 am when human activities start and a lot of used water flows in, there is no time lag in the aeration cycle, and there is no service. There is an advantage that the processing is effectively performed in an optimal aerobic / anaerobic state in accordance with the current situation, without the troublesome adjustment work of frequent setting changes at a low load such as in the initial stage.

In the operation control method of an aeration apparatus in which aerobic treatment and anaerobic treatment are alternately performed in time series by continuously stirring and intermittently aeration of sewage in the aeration tank, the inside of the tank supplied with air by the aeration apparatus The dissolved oxygen change value is detected by a dissolved oxygen sensor provided in the tank, the detection signal is processed by the control device, and a signal is transmitted to the inverter that controls the rotation of the aeration device. Start of aeration in the case of aerobic treatment based on the sampling time, which is the detection period of water, the dissolved oxygen index value for calculating the inflow load of sewage, and the dissolved oxygen target value for ensuring a stable nitrification reaction Until the dissolved oxygen index value is reached, the aeration apparatus is rotated at a constant speed, and the aeration stop in the anaerobic treatment of the next process is performed based on the inflow load amount calculated from the arrival time until the dissolved oxygen index value. Anaerobic time is calculated, and further, in order to reach quickly the dissolved oxygen target value from the arrival of the dissolved oxygen index value, it determines whether the dissolved oxygen value of current is increased for each of the sampling time, nonincreasing given case issues a command to increase the frequency of the inverter, the determination if the increased operation control aeration device issues a command to continue the frequency operating state at that time, upon reaching the dissolved oxygen target value During the constant dissolved oxygen control operation time, the aeration apparatus is controlled at a variable speed so that the dissolved oxygen value in the aeration tank is maintained in the dissolved oxygen index value state. In the case of anaerobic treatment in the next process, the dissolved oxygen constant control is performed. When the operating time has elapsed and the aerobic device is stopped at the calculated anaerobic time, the dissolved oxygen value decreases and the anaerobic treatment is continued.When the anaerobic time elapses, the aeration device starts again and the next aerobic time is reached. That aeration was started to resume aerobic process, thereby properly performed intermittently operation control of the aeration device to repeat alternately aerobic treatment and anaerobic treatment. In addition, the dissolved oxygen change value in the tank supplied with air by the aeration apparatus is detected by a dissolved oxygen sensor provided in the tank, the detection signal is processed by the control apparatus, and a signal is sent to the inverter that controls the rotation of the aeration apparatus. In the case of aerobic treatment, dissolved oxygen from the start of aeration based on the sampling time which is the detection cycle of the dissolved oxygen value set in advance and the dissolved oxygen index value for calculating the inflow load of sewage The aeration apparatus is rotated at a constant speed until the index value is reached , and the anaerobic time for aeration stop in the anaerobic treatment of the next process is calculated based on the inflow load amount calculated from the arrival time until the dissolved oxygen index value. , further, the dissolved oxygen value control operation time is calculated by the aerobic time obtained from the ratio of a preset aerobic-anaerobic time based on the anaerobic time subtracting the arrival time Dynamically set processing, after reaching the time course of dissolved oxygen index value, the dissolved oxygen value control operation time set out the calculated, since the initial to reach quickly dissolved oxygen target value, the current in each of the sampling time Dissolved It is determined whether or not the oxygen value is increasing. When the oxygen value is not increased, a command to increase the frequency of the inverter is issued. When the determination is increased, a command is issued to continue the frequency operation state at that time. The aeration apparatus is controlled to operate , and after reaching the dissolved oxygen target value, the aeration apparatus is controlled to operate at a variable speed so as to maintain the dissolved oxygen value in the aeration tank in the dissolved oxygen target value state.

  1 to 4, 1 is an aeration tank, 2 is an agitator provided to generate a stirring water flow in the aeration tank 1, and 3 is an aeration apparatus for supplying air into the aeration tank 1. 3 is supplied with oxygen by an air diffuser 5 installed in the aeration tank 1 via an air pipe 4 led from 3, and a dissolved oxygen sensor 6 provided in the aeration tank 1 detects the dissolved oxygen value. The detected signal is converted into a dissolved oxygen value signal by the dissolved oxygen converter 7, and the converted dissolved oxygen value signal is processed by the control device 8, and a signal is transmitted to the inverter 9 that controls the rotation of the aeration device 3. Based on the preset sampling time t1, the dissolved oxygen index value D1 for calculating the inflow load of sewage and the dissolved oxygen target value D2 for ensuring a stable nitrification reaction, In the dissolved oxygen level May be detected by the dissolved oxygen sensor 6 only during the aerobic time t4 at each sampling time t1, but it is preferable that the oxygen is continuously detected during the anaerobic time t3. First, based on the signal detected by the dissolved oxygen sensor, the aeration device 3 is driven at a constant speed operation by a command signal from the control device to the inverter to start aeration, and the dissolved oxygen value reaches the dissolved oxygen index value D1. In the case of non-reaching, the constant speed operation is continued. If it is determined that it has arrived, the arrival time t0 required until the arrival and the amount of air supplied during the arrival time t0 are determined. The inflow load amount is calculated, and the anaerobic time t3 for stopping the aeration in the anaerobic processing of the next process is calculated from the inflow load amount and automatically set.

  Further, in order to reach the dissolved oxygen target value D2 as soon as the dissolved oxygen index value D1 is reached, it is determined whether or not the current dissolved oxygen value is increasing at every preset sampling time t1, and if not, If the control device 8 sends a command signal for increasing the frequency to the inverter 9 to determine that the aeration device 3 has been speeded up and the current dissolved oxygen value has increased, then the frequency operation state at that time is continued, It is determined whether or not the dissolved oxygen value has reached the dissolved oxygen target value D2. If not, the control operation for increasing the current dissolved oxygen value in the previous step is performed again, and it is determined that the dissolved oxygen value has been reached. For example, a predetermined dissolved oxygen constant control operation time t2 is set, and during the time t2, it is determined whether or not the current dissolved oxygen value is equal to the dissolved oxygen target value D2 at every preset sampling time t1, and the dissolved oxygen target value is determined. D2 When the signal is low, a command signal for increasing the frequency is transmitted to the inverter 9 by the control device 8. Conversely, when the signal is high, a command signal for decreasing the frequency is transmitted, and when the frequency is equal, the frequency operation state at that time is continued. After the variable speed operation control of the aeration apparatus 3 corresponding to each situation is continued for the dissolved oxygen constant control operation time t2, the process proceeds to the anaerobic process of the next step.

  Next, in the anaerobic process of the next step, the aeration apparatus 3 is stopped at the calculated anaerobic time t3, the dissolved oxygen value is lowered and the anaerobic state is continued. When the anaerobic time t3 elapses, the aeration apparatus 3 is activated again. The aeration is started at the next aerobic time t4, the aerobic state is resumed, and the operation control of the aeration apparatus 3 is intermittently performed in the aeration cycle C in which the aerobic process and the anaerobic process are appropriately repeated alternately.

Based on the operation control method of the first embodiment, the inflow load amount calculated based on the arrival time t0 required to reach the dissolved oxygen index value D1 from the start of aeration and the amount of air supplied during the arrival time t0 is calculated. and calculate the dissolved oxygen value control operating time t2 c by subtracting the arrival time t0 from aerobic time t4 determined from the ratio of a preset aerobic-anaerobic time anaerobic time t3, which is calculated based on well, also may be calculated directly dissolved oxygen value control operating time t2 c from the inflow load the current obtained by the calculation using the load processing coefficients empirical value of experiments, is the calculated automatically setting process dissolved oxygen value control operating time t2 c is, after reaching time t0 course of dissolved oxygen index values D1, initial in the calculated output set dissolved oxygen value control operating time t2 c is quickly dissolved oxygen target The aeration apparatus 3 is controlled to increase the dissolved oxygen value in order to reach the value D2, and after reaching the dissolved oxygen target value D2, the aeration is performed so that the dissolved oxygen value in the aeration tank is maintained in the dissolved oxygen target value D2 state. The apparatus 3 is controlled to operate at a variable speed.

It is a system configuration | structure figure of the aeration equipment made into the implementation object of this invention operation control method. It is a top view of the aeration equipment which enforces this invention operation control method. It is a dissolved oxygen diagram which shows the operation control method in Example 1 of this invention. It is a flowchart of the operation control method in Example 1 of this invention. It is a dissolved oxygen diagram which shows the operation control method in Example 2 of this invention. It is a flowchart of the operation control method in Example 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Aeration tank 3 Aeration apparatus 6 Dissolved oxygen sensor 8 Control apparatus 9 Inverter D1 Dissolved oxygen index value D2 Dissolved oxygen target value t0 Arrival time to dissolved oxygen index value t1 Sampling time t2 Dissolved oxygen constant control operation time
t2c dissolved oxygen target value control operation time t3 anaerobic time t4 aerobic time

Claims (2)

In the operation control method of an aeration apparatus in which aerobic treatment and anaerobic treatment are alternately performed in time series by continuously stirring and intermittently aeration of sewage in the aeration tank, the inside of the tank supplied with air by the aeration apparatus The dissolved oxygen change value is detected by a dissolved oxygen sensor provided in the tank, the detection signal is processed by the control device, and a signal is transmitted to the inverter that controls the rotation of the aeration device. In the case of aerobic treatment, aeration is started based on the sampling time, which is the detection period of water, the dissolved oxygen index value for calculating the inflow load of sewage, and the dissolved oxygen target value for ensuring a stable nitrification reaction Until the dissolved oxygen index value is reached, the aeration apparatus is rotated at a constant speed, and the aeration stop in the anaerobic treatment of the next process is performed based on the inflow load amount calculated from the arrival time to the dissolved oxygen index value. Anaerobic time is calculated, and further, in order to reach quickly the dissolved oxygen target value from the arrival of the dissolved oxygen index value, the dissolved oxygen value to current state determines whether or not the incremented each said sampling time, non In the case of an increase, a command to increase the frequency of the inverter is issued, and in the case where the determination is an increase, a command is issued to continue the frequency operation state at that time to control the operation of the aeration apparatus, and the dissolved oxygen target value is reached. During a predetermined dissolved oxygen constant control operation time, the aeration apparatus is controlled at a variable speed so as to maintain the dissolved oxygen value in the aeration tank at the dissolved oxygen target value state. In the case of anaerobic treatment in the next process, the dissolved oxygen constant is controlled. When the control operation time elapses and the aerobic device is stopped during the calculated anaerobic time, the dissolved oxygen value is lowered and the anaerobic treatment is continued. Takes to resume started aerobic treatment aeration, proper to characterized in that intermittently perform operation control of the aeration device to repeat alternately aerobic treatment and anaerobic treatment, the operation control method of the aeration device. In the operation control method of an aeration apparatus in which aerobic treatment and anaerobic treatment are alternately performed in time series by continuously stirring and intermittently aeration of sewage in the aeration tank, the inside of the tank supplied with air by the aeration apparatus The dissolved oxygen change value is detected by a dissolved oxygen sensor provided in the tank, the detection signal is processed by the control device, and a signal is transmitted to the inverter that controls the rotation of the aeration device. In the case of aerobic treatment, the aeration apparatus from the start of aeration until reaching the dissolved oxygen index value based on the sampling time that is the detection period of the gas and the dissolved oxygen index value for calculating the inflow load of sewage the rotating at a constant speed, anaerobic time in the aeration stop is calculated in anaerobic treatment of the next step based on the inflow load amount calculated from the arrival time to the dissolved oxygen index value, further aerobic-set in advance The more the ratio of air time dissolved oxygen value control operating time from aerobic time obtained based on anaerobic time by subtracting the arrival time is calculated automatically by setting processing, the arrival time course of dissolved oxygen index values Thereafter, in the calculated and set dissolved oxygen target value control operation time, in order to quickly reach the dissolved oxygen target value in the initial stage, it is determined whether or not the current dissolved oxygen value is increasing at each sampling time, and is not increased. In this case, a command to increase the frequency of the inverter is issued, and when the determination is increased, a command is issued to continue the frequency operation state at that time to control the operation of the aeration apparatus, and after reaching the dissolved oxygen target value Is a variable speed operation control of the aeration apparatus so that the dissolved oxygen value in the aeration tank is maintained at the dissolved oxygen target value state.

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