JP6964330B2 - Aeration system and wastewater treatment method in wastewater treatment equipment - Google Patents

Description

The present invention relates to an aeration system in a wastewater treatment facility, and relates to an aeration system capable of controlling the operating state of a blower for supplying air to an aeration tank used in an activated sludge method wastewater treatment facility.

Generally, wastewater treatment by the activated sludge method decomposes organic matter by microorganisms (aerobic bacteria) and satisfies the biochemical oxygen demand (BOD), so that solid-liquid separation can be performed by a settling tank or a separation membrane. It is possible to purify the waste with the waste removed. In the process of such wastewater treatment, aeration is performed to activate the activity of microorganisms, and the aeration is usually sent into the aeration tank by a blower.

By the way, the blower used for aeration is an electrically operated air pump, which is constantly operated continuously in order to maintain the activity of microorganisms. In addition, an anaerobic-aerobic activated sludge method is also adopted as a method for removing not only organic substances but also nitrogen and phosphorus, and dissolved oxygen (DO: Dissolved Oxygen) is performed by intermittent aeration in the same treatment tank. There is something that adjusts the concentration. In such an anaerobic-aerobic activated sludge method by intermittent aeration, the activity status of microorganisms cannot be grasped only by measuring the dissolved oxygen concentration, and as a result, organic substances are not decomposed, and there is no sludge storage in the settling tank. It has been pointed out that in the case of an oxygen state, a denitrification reaction occurs, and a phenomenon that nitrogen gas adheres to sludge and floats occurs (see Patent Document 1). Therefore, in order to realize a suitable anaerobic-aerobic activated sludge method, a technique for controlling the aeration operation time while measuring the dissolved oxygen or the treatment temperature has been devised (see Patent Documents 2 and 3). There is.

Japanese Unexamined Patent Publication No. 8-117783 Japanese Unexamined Patent Publication No. 2000-308896 Japanese Unexamined Patent Publication No. 2011-20050

By the way, the intermittent aeration in the aeration tank as described above is for realizing the anaerobic-aerobic activated sludge method, but it is not necessary to form an anaerobic atmosphere in order to decompose organic substances, especially nitrogen and nitrogen. When the decomposition of phosphorus is not required, the activated sludge method by continuous aeration has been adopted. In particular, in the treatment of domestic wastewater, the treatment tank becomes large and the treatment equipment becomes expensive in order to perform the denitrification treatment and the dephosphorification treatment, so that it is required to decompose organic matter exclusively.

However, even when the active sludge method is used to decompose only organic matter in an aerobic atmosphere, continuous operation of the blower not only increases power consumption but also consumes the blower. Could have been the cause of attracting. Therefore, the blower has to be additionally installed with a spare blower for replacement, and there is also a need to continuously aerate with the spare blower during the replacement period. Furthermore, it induces an increase in hydrogen ion concentration due to over-aeration, which may result in a state unsuitable for treated water.

The present invention has been made in view of the above points, and an object of the present invention is to intermittently use a blower in consideration of the inflow and outflow of wastewater and the excess / deficiency of aeration, depending on the conditions in the treatment tank. It is to provide an aeration system capable of operating the system, thereby reducing power consumption and extending the life of the blower, and providing an efficient wastewater treatment method.

Therefore, the present invention relating to the aeration system is to determine the operating time of the blower in order to intermittently operate the blower in the active sludge method wastewater treatment facility including the aeration tank and the blower for supplying air into the aeration tank. The control unit includes a control unit that controls a stop time, and the control unit has a calendar function and a clock function, and a storage unit that stores a plurality of standard intermittent operation time information classified into a plurality of types according to a processing date and a processing time. The control unit controls the operating state of the blower by selecting the processing date specified by the calendar function and the clock function from the standard intermittent operation time information and the standard intermittent operation time information matching at the time of processing. It is characterized by being.

According to the above configuration, the blower can be intermittently operated by the standard intermittent operation time information corresponding to a specific day and a specific time zone. That is, the inflow of wastewater can be classified together with the time zone, day of day, other seasonal factors, etc., and under conditions where the inflow of wastewater increases, intermittent operation is performed by an operation mode in which the aeration time is prolonged. The aeration time can be shortened under the condition that the inflow of wastewater is reduced. As a result, the activity of aerobic bacteria is activated by increasing the supply of oxygen into the aeration tank during the period when the inflow of wastewater is large, and conversely, the supply of oxygen during the period when the inflow of wastewater is small. The amount can be suppressed to suppress the activity of aerobic bacteria. As a result, it is possible to avoid a state of over-aeration and limit the operating time of the blower.

In the above invention, the standard intermittent operation time information is based on a major division according to the distinction between summer, winter and spring / autumn, a middle division according to the distinction between weekdays and holidays, and a subdivision that distinguishes 24 hours every hour. It can be configured to be set. In the case of such a configuration, for example, the temperature rises in the summer based on the intermediate temperature in the spring and autumn, and the activity of microorganisms becomes active, so that the oxygen supply amount is increased as compared with the spring and autumn. Since the operating time of the blower is lengthened so as to cause the blower to be operated, the temperature is lowered in winter, and the activity of microorganisms is reduced. Therefore, the standard intermittent operating time information for the whole year can be set so as to shorten the operating time. Furthermore, based on the day of the week etc. by the calendar function, the standard intermittent operation time information is further subdivided according to the division between weekdays and holidays, or the distinction between daytime and nighttime, and it is detailed by appropriately selecting it. It is possible to adjust the driving situation.

Further, the present invention relating to the aeration system is a wastewater amount for measuring the inflow amount of wastewater flowing into the aeration tank in an activated sludge method wastewater treatment facility including an aeration tank and a blower for supplying air into the aeration tank. The control unit includes a measuring means and a control unit that controls the operation time and the stop time of the blower in order to operate the blower intermittently. A storage unit that stores intermittent operation time information, and the control unit controls the operating state of the blower by selecting standard intermittent operation time information that matches the inflow amount of wastewater detected by the wastewater amount measuring means. It is characterized by being.

According to the above configuration, suitable standard intermittent operation time information can be selected according to the actual inflow amount of wastewater, and a plurality of standard intermittent operation time information can be changed according to the ever-changing drainage situation. While wastewater can be treated. This makes wastewater treatment suitable, and eliminates extra aeration time, that is, excessive operating time of the blower, which contributes to labor saving.

In each of the above inventions, an oxygen state measuring means for measuring the oxygen supply state for the water to be treated in the air exposure tank is further provided, and the control unit is based on the value detected by the oxygen state measuring means. It may be possible to modify the operating time and the stopping time of the blower forming the intermittent operation time information and any or all of the time per cycle thereof.

According to the above configuration, basically, the excess or deficiency of the aeration state is determined based on the value of the oxygen supply state measured by the oxygen measuring means of the water to be treated during the continuous operation of the blower, and based on the result. , The blower should be stopped, or the time zone in which it can be stopped is calculated. It should be noted that the measurement of the inflow amount of wastewater is to obtain a condition for detecting the drainage status for each divided time and calculating the treatment speed of the wastewater according to the inflow amount of the wastewater. In addition, since the intermittent operation time can be temporarily corrected due to changes in the situation based on the standard intermittent operation time information, if a large amount of wastewater flows in unexpectedly, or conversely, the expected inflow amount will not be reached. In some cases, the balance between the operation time and the stop time can be changed as appropriate according to the situation. This makes it possible to avoid discharging the wastewater in an untreated state and to avoid a state of over-aeration.

Here, as the oxygen state measuring means, there may be a configuration in which a redox potential meter is provided in the aeration tank. The redox potential meter can measure whether the water to be treated is in an oxidized state or a reduced state as a potential difference (voltage value), measures a positive potential in the oxidized state, and is aerobic in such an oxidized state. In the reduced state, a negative potential can be measured, and in the reduced state, an anaerobic state (non-aerobic state) can be detected. Depending on the magnitude of the positive or negative potential at this time, the strength of the oxidizing state (aerobic state) or reducing state (anaerobic state) can be detected, so that the state of insufficient aeration or the state of over-aeration can be detected. be able to.

In addition to the above, the oxygen state measuring means may include a DO concentration meter provided in the aeration tank and a pH sensor for measuring the pH value of the treated water. When the DO value is 0 or less, all of them show a value of 0. Therefore, it is possible to detect that the treated water is aerobic by confirming that the DO concentration is> 0. The pH value of the treated water is measured in order to detect an increase in hydrogen ions due to over-aeration.

Further, the present invention relating to the aeration system is a wastewater amount for measuring the inflow amount of wastewater flowing into the aeration tank in an activated sludge method wastewater treatment facility including an aeration tank and a blower for supplying air into the aeration tank. The operating time of the blower for intermittently operating the blower based on the measuring means, the oxygen state measuring means for measuring the oxygen supply state for the water to be treated in the aeration tank, and each value detected by the oxygen state measuring means. It is characterized by including a control unit for controlling the stop time.

According to the above configuration, it is possible to determine the state to be treated while measuring the amount of wastewater inflow, and operate the blower so as to obtain a suitable aeration state. At this time, for example, by storing the daily situation for each hour, it is possible to obtain the pattern information of the wastewater treatment while operating the treatment facility. Based on the information obtained at this time, it is also possible to set the blower movement plan for the whole year as standard intermittent operation time information.

In each of the above inventions, the operating time and the stopping time of the blower can be in the range of 15 seconds to 7200 seconds for one cycle. In the case of such a configuration, the range of time selection for one cycle can be widened according to the ratio of the operation time and the stop time. For example, when the inflow amount of wastewater is extremely small, the stop time is set longer than the operation time. At this time, by setting the time for one cycle longer, the activity of microorganisms is suppressed. However, the downtime can be as long as possible (power consumption can be reduced). Contrary to the above, when the inflow of wastewater is large, the ratio of operating time will be increased, but by shortening the time of one cycle, oxygen into the aeration tank during the downtime will be increased. The time during which the supply drops can be shortened. Further, even when the operation time and the stop time should be the same ratio, by shortening the time of one cycle, it is possible to maintain a state in which the oxygen supply does not significantly decrease. Then, even in such a situation, a stop time is surely provided, and the power consumption during that time can be suppressed.

On the other hand, the present invention relating to the wastewater treatment method is a wastewater treatment method using the above-mentioned aeration system, in which the control unit matches the treatment date and the standard intermittent operation time specified by the calendar function and the clock function. There is a mode in which information is selected and the operating state of the blower is controlled based on the standard intermittent operation time information, and the control unit performs standard intermittent operation that matches the inflow amount of wastewater detected by the wastewater amount measuring means. There is a mode in which time information is selected and the operating state of the blower is controlled based on the standard intermittent operation time information. Further, the operation time and the stop time of the blower forming the standard intermittent operation time information based on the value detected by the oxygen state measuring means while the control unit selects the standard intermittent operation time information, and one of these. There is a mode in which any or all of the time per cycle is modified and the operating state of the blower is controlled based on the modified standard intermittent operation time information. Further, as a case where it is not based on the standard intermittent operation time information, the operation time of the blower for the control unit to intermittently operate the blower based on each value detected by the drainage amount measuring means and the oxygen state measuring means. There is a form of controlling the stop time.

With any of the above configurations, the intermittent operation of the blower can be properly controlled, and the wastewater treatment by the activated sludge method can be performed while appropriately controlling the amount of wastewater flowing into the aeration tank and the oxygen supply state to the water to be treated. Can be made possible.

According to the present invention relating to the aeration system, when the blower is intermittently operated based on the standard intermittent operation time information, the operation of the blower is stopped in a situation where aeration is not originally required, and the power consumption is consumed. Can be reliably reduced. Further, since the blower stop time is the time during which the blower does not operate at all, the life of the blower can be extended. This makes it possible to reduce the burden on the operation of the wastewater treatment equipment.

In addition, depending on the conditions inside the treatment tank, especially when considering the inflow rate of treated water and the excess / deficiency of aeration, when operating the blower intermittently, firstly, the treatment of wastewater should be sufficient. At the same time, the blower can be effectively stopped, and secondly, the information necessary for creating the standard intermittent operation time information can be obtained by storing the information of the situation. Further, while the blower is intermittently operated based on the standard intermittent operation time information, the intermittent operation status can be corrected when there is an unexpectedly large amount of drainage or the inflow amount is unexpectedly small. As a result, wastewater can be treated without excess or deficiency.

On the other hand, according to the present invention relating to the wastewater treatment method, since the aeration system is used, a suitable aeration state can be realized while the blower is operated intermittently. In wastewater treatment, by controlling the state of intermittent operation of the blower, it is possible to make sure that there is no excess or deficiency of the supply of the mountain to the water to be treated, and effective treatment can be realized with low power consumption.

It is explanatory drawing which shows the Embodiment of this invention concerning an aeration system. It is a block diagram which shows the system configuration of an embodiment. It is a flow chart which shows the control method by a control part. It is a flow chart which shows the control method by a control part. It is explanatory drawing which shows the modification of embodiment which concerns on an aeration system. It is a flow figure which shows the control method by the modification of embodiment. It is a flow figure which shows the control method by the modification of embodiment. It is a flow chart which shows the modification of the control method by a control part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of an embodiment of the present invention relating to an aeration system. As shown in this figure, the outline of the aeration system A of the present embodiment is as follows: an aeration tank 1 arranged as a treatment tank in the center of the wastewater treatment facility B, and air (oxygen) is supplied to the aeration tank 1. The blower 2 is provided with a control unit 3 for controlling the operating state of the blower 2.

The wastewater treatment facility B is provided with an inflow tank 4 for storing wastewater and allowing the wastewater to flow into the aeration tank 1, and the inflow tank 4 is configured to temporarily store the wastewater. In some cases, settling tanks that allow solid-liquid separation may be used. Further, the treated water treated in the aeration tank 2 flows into the settling tank 5 provided as a discharge tank to settle the aggregated and flocified solid matter, and only the supernatant portion can be discharged by solid-liquid separation. ing. The discharge tank is composed of a settling tank 5 as shown in the figure, but the settling tank 5 may be separately provided with a discharge tank for temporarily storing treated water. In some cases, a trap is provided in the settling tank 5 to remove suspended matter.

By the way, the aeration tank 1 is provided with an aeration pipe 11, which is connected to the blower 2 by an air supply pipe 12, and the air supplied from the blower 2 is ejected from the bottom of the aeration tank 1. The air ejected by the aeration pipe 11 diffuses inside the aeration tank 1, agitates the drainage flowing into the aeration tank 1, and dissolves oxygen in the drainage. Further, the aeration tank 1 decomposes organic matter in wastewater by anaerobic bacteria (microorganisms) that decompose organic matter in an anaerobic atmosphere. In order to effectively activate this aerobic bacterium, it is necessary to dissolve an appropriate amount of oxygen in the wastewater.

In this embodiment, aeration (air supply) is performed intermittently while appropriately maintaining the ability of aerobic bacteria to decompose organic substances, and the blower 2 is operated intermittently for that purpose. Intermittent operation is a state in which an operating state and a stopped state are alternately repeated. In the operating state, air is supplied to the air diffuser pipe 11 to aerate the air. It is in a state where it is not supplied and is not aerated. Such intermittent operation is for reducing power consumption due to the movement of the blower 2 and extending the life of the blower 2.

The intermittent operation of the blower 2 does not simply repeat the operation state and the stopped state alternately, so that the activity of the aerobic bacteria is maintained so that the decomposition of the organic matter by the aerobic bacteria is preferably performed. The desired air must be supplied. Therefore, the control unit 3 controls the state of intermittent operation so that the activity of aerobic bacteria becomes suitable.

Specifically, a dissolved oxygen concentration meter (DO concentration meter) 13 which is a DO measuring means is installed in the aeration tank 1, and the dissolved oxygen concentration of wastewater inside the aeration tank 1 is measured, and the concentration is 0 or less. The air supply time is controlled so as not to become. In addition, when the dissolved oxygen concentration becomes excessive due to over-aeration, the hydrogen ion concentration in the treated water increases, so that the aeration is appropriately interrupted (the blower 2 is stopped) so as not to cause over-aeration. I'm in control. The hydrogen ion concentration is measured by a pH sensor 51, which is a pH measuring means provided in the settling tank 5 installed as a discharge tank, and the hydrogen ion concentration is detected by the pH value. In the case of such a configuration, the oxygen supply state of the water to be treated is measured by the DO concentration meter 13 and the pH sensor 51, and in this sense, it shows one form in which the oxygen state measuring means is formed by both.

The amount of drainage flowing from the inflow tank 4 into the aeration tank 1 is measured by a flow meter 14 which is a flow rate measuring means, and the state of aeration can be changed depending on the degree of the flow rate. Further, although the aeration tank 1 is single in the figure, a plurality of aeration tanks 1 may be provided side by side. When a plurality of aeration tanks are provided, the air supply may be branched from a single blower 2, or a plurality of blowers may be provided for each aeration tank and the intermittent operation state may be individually controlled. In this case, the control unit can input the processing status for each of a plurality of aeration tanks and output individual output values.

As shown in FIG. 2, the system configuration of the present embodiment includes an input unit 7 that enables input from various external measurement types 6 and input for setting other conditions to the control unit 3. The blower 2 is controlled by the control unit 3 in response to these inputs. Examples of the external measurement class 6 include the above-mentioned DO concentration meter 13, flow meter 14, pH sensor 51, thermometer 61, and the like, but other instruments are provided in order to obtain necessary information. May be good. Although the redox potential meter 15 is described in the external instruments 6 in the figure, the redox potential meter 15 is used instead of the oxygen state measuring means composed of the DO concentration meter 13 and the pH sensor 51. It may function as a state measuring means. Further, the configuration may include all of them without selectively using them.

The control unit 3 has a built-in timer 31 and a calendar 32, and the timer 31 is used for measuring the operation time and the stop time for the blower 2 and for obtaining the time (24 hours) of the operation day. , Calendar 32 is used to identify the driving date. This specification of the operating day is incorporated into the operating conditions in order to obtain the weather conditions such as summer or winter as a prediction of the inflow of wastewater such as weekdays or holidays. The time (24 hours) of the operation day by the timer 31 is used to detect the time zone of drainage such as morning or afternoon, early morning or midnight.

Further, the control unit 3 is provided with a storage unit 33, and the operating status of the wastewater treatment facility B is accumulated as the inflow amount of wastewater by dividing the time every day. The standard intermittent operation time information calculated from the information or standardizing the expected movable pattern of the blower 2 can be stored. An arithmetic unit 34 is provided for the arithmetic processing and for determining the state of the wastewater treatment of the aeration tank 1 during actual operation, and the operation of the blower 2 is performed according to the arithmetic result by the arithmetic unit 34. An output unit 35 for outputting a signal for operating (ON switch) or stop (OFF switch) is provided.

The blower 2 operates the operation (ON switch) and the stop (OFF switch) by the signal output from the output unit 35, and realizes the intermittent operation at a predetermined interval. An electromagnetic switch is used for the ON switch and the OFF switch, and the signal output from the output unit 35 is either an increase in voltage with respect to the electromagnet on the ON side or an increase in voltage with respect to the electromagnet on the OFF side. , It is output to the electromagnetic switch.

In addition to the above, in the intermittent operation of the blower 2, the motor that operates the blower 2 can be controlled to switch between the operation time and the stop time by PWM (Pulse Width Modulation) control. The ratio of the operation time to the stop time is processed by the duty ratio, and the time per cycle of the operation / stop can be controlled by changing the pulse cycle. According to PWM control, the life of the switching circuit can be longer than when an electromagnetic switch or the like is used.

It should be noted that the storage unit 33 can store in advance the assumed operating condition as standard intermittent operation time information at the beginning of operation. This data can be input by the input unit 7, and the data to be input includes the maximum and minimum values of the drainage inflow, the difference in the drainage inflow between weekdays and holidays, and the daytime and nighttime. Depending on the difference in the amount of wastewater inflow, it is input to specify the time zone to be frequently aerated or to suppress the aeration. In addition, assuming that the calendar 32 is used, the period in which the air temperature or the temperature of the wastewater rises, the period in which the temperature of the wastewater decreases, etc. is input, and the activity of microorganisms becomes active at the time of high temperature, so that the time zone of aeration is increased. Then, enter information such as reducing the aeration time because the activity of microorganisms is suppressed at low temperatures. As a result, the standard intermittent operation time information is set throughout the year, and basically, the operation of the blower 2 is controlled based on the standard intermittent operation time information.

By the way, even when the standard intermittent operation time information is set, suitable wastewater treatment cannot be performed by the standard intermittent operation time information, and therefore, the output should be corrected (or the standard intermittent operation time information should be corrected). Can be requested. For example, if the amount of wastewater discharged is assumed to be small on holidays, but if the day designated as a holiday from the calendar information flows in the same amount of wastewater as on weekdays, or if the amount of wastewater flows in is extremely smaller than usual. , It is necessary to correct the output state only on that day (or several hours).

Therefore, in the present embodiment, the amount of wastewater inflow is constantly measured by the flow meter 14, and this is input to the control unit 3, so that the operation is corrected to the intermittent operation due to the operation condition different from the standard intermittent operation time information. .. Therefore, the standard intermittent operation time information means a standard intermittent operation mode (standard mode), and in the case of wastewater treatment within the expected range, the standard intermittent operation time information is prioritized, but it is assumed. When it deviates from the range (exceeds the assumed range or does not reach the assumed range), a method of switching to the intermittent operation mode (control mode) by the control unit 3 can be taken. In addition, in the selection of the intermittent operation time in the standard mode, the standard mode and the control mode may be switched by linking the inflow amount information of the wastewater and checking only the inflow amount, but the wastewater treatment In order to control the state of the above, it is preferable to use the dissolved oxygen concentration in the aeration tank 1 as an index.

Next, the control method by the control unit 3 will be described. FIG. 3 is a diagram showing a flow of intermittent operation control of the blower based on the standard intermittent operation time information. This method of intermittent operation control shows a case where a part of the standard intermittent operation time information is used as a reference and a part of the information is corrected.

As shown in FIG. 3, when the control is started, the initial setting is first performed (S101). The initial setting is the setting of the control mode based on the standard intermittent operation time information, and in particular, the setting for linking with the calendar and the timer is performed. Subsequently, the standard intermittent operation time information is read out (S102), and the intermittent operation mode is determined by linking with the calendar information or the like (S103). The standard intermittent operation time information to be read out is preset according to the day and time division in which the controlled operation is performed. For example, if it is 9:00 am on weekdays in July, it will be in the morning on weekdays in summer, and if it is 3:30 pm on holidays in January, it will be in the afternoon on winter holidays. A predetermined ratio of the operation time to the stop time and the time of one cycle thereof are set according to these categories. Then, the standard intermittent operation time information is changed according to the passage of time in the above division, and the control is executed in a state where the change of the setting with the passage of time is read in advance together with the time axis.

The intermittent operation condition is output to the blower according to the time determined in the above (S104), and the blower operates in accordance with the intermittent operation condition. At the same time, the dissolved oxygen concentration (DO value) in the aeration tank is measured, and the value is input (S105). This dissolved oxygen concentration value is for confirming the amount of oxygen supplied by intermittent aeration, and the measured value of the dissolved oxygen concentration is a state of the dissolved oxygen concentration because all 0 or less are 0 values. Is determined by whether or not it is not "0" (S106), and if it is "0", it is considered that the dissolved oxygen concentration is insufficient, and if it is not "0", sufficient dissolved oxygen is present. It is regarded as a thing. The unit of the detected dissolved oxygen concentration is mg / L.

Therefore, if there is sufficient dissolved oxygen, there is a possibility of over-aeration, so check the hydrogen ion concentration in the discharge tank. Specifically, the pH value is acquired by a pH sensor and the hydrogen ion concentration is estimated (S107). This is because when the hydrogen ion concentration increases, it becomes acidic and the pH value decreases. Therefore, the pH is set to 7 as the threshold value, and in a situation where the pH is lower than "7", the hydrogen ion concentration is clearly increased, which is considered to be caused by over-aeration. Although this threshold value can be set arbitrarily, it is stipulated that it cannot be discharged when the pH is 5.8 or less. Therefore, in order to grasp the increasing tendency of hydrogen ions at an early stage, the threshold value is set to pH 7 here (). S108). Therefore, when the pH value is 7 or more, it is assumed that the aeration state is good, and the intermittent operation mode is continued, but when the pH value is lower than 7, it is confirmed whether or not the aeration is over-aeration.

Therefore, first, the value of the dissolved oxygen concentration in the aeration tank is acquired again (S109), and the dissolved oxygen concentration due to aeration is confirmed. Here, when the dissolved oxygen concentration is "2.0" (mg / L) or more, there is a possibility of over-aeration, so 2.0 mg / L is set as the threshold value (S110). If it is less than 2.0, it is not considered as over-aeration and the intermittent operation is continued under the same operating conditions. However, if there is a possibility of over-aeration, the intermittent operation conditions are further modified according to the situation. The content is decided.

That is, first, in order to determine whether the state of over-aeration is temporary or continuous, the tendency of fluctuations in the pH value is confirmed (S111). When this fluctuation tends to decrease and falls below the threshold value of pH 7 for the first time, a temporary over-aeration state is assumed, and it is considered that the cause is the variation due to the blower operating time being too long. be able to. Therefore, in this case, the time of one cycle is modified to be shortened (S112). On the other hand, when the pH value is continuously low in comparison with the previously measured value, it can be considered that the cause is an imbalance between the operating time and the stopping time of the blower. In this case, the ratio (balance) of the operation time is changed to increase the ratio of the stop time (S113). In any of the modifications, after selecting from the scheduled conditions of the intermittent operation mode due to these modifications and determining the operation mode (S114), the determined mode is output to the blower (S104). After the fact, it will be operated intermittently under the changed conditions. In the above, the modified condition is output to the storage unit together with other information, and the standard intermittent operation time information is updated (S115).

By the way, in the initial input of the dissolved oxygen concentration (S105), when the value is "0" (S106), the content is determined so as to correct the state of aeration. That is, when the dissolved oxygen concentration shows a decreasing tendency, it is judged that the stop time is long as a temporary aeration failure, and the time of one cycle is shortened and the interval of the aeration time is shortened to deal with it (S121). ). On the other hand, when the dissolved oxygen concentration is continuously reduced, it is assumed that the balance between the operating time and the stopping time of the blower is imbalanced, and the balance is corrected (S122).
Then, the modification of these operation modes is selected stepwise from the scheduled conditions, and after the selected mode is determined (S123), the mode according to the conditions is output to the blower (S104). After that, it will be operated intermittently according to the changed conditions. Further, when the condition is modified in this way, the information is output to the storage unit together with other information, and the standard intermittent operation time information is updated (S124).

By the control method as described above, it is possible to perform the optimum wastewater treatment while modifying the standard intermittent operation time information initially set as a reference. In addition, since the standard intermittent operation time information is updated every time it is corrected as appropriate, after the fact, wastewater treatment is performed according to the updated standard intermittent operation time information, and this is repeated to obtain a suitable state. Wastewater treatment will be continued at.

Further, as a control method, there is also a method of deriving a suitable intermittent operation time from the default setting without providing standard intermittent operation time information. A flow chart of this control method is shown in FIG.

As shown in FIG. 4, when the control is started, the default setting is made as the intermittent operation mode. By default, the blower operation time and stop time are equalized, and the time per cycle is set to 300 seconds. The initial value of this cycle time is arbitrary and can be started from 7,200 seconds at the maximum, but in the case of general processing equipment, about 300 seconds is a common sense value.

Therefore, the process is started in the state set by default, the dissolved oxygen concentration is detected (S204), or the pH value is input (S207) to determine the excess or deficiency of the aeration state (S205, 207). Regarding shortening the cycle time (S212, S221) or changing the balance between the operation time and the stop time (S211 and S222) as necessary, the same as when based on the standard intermittent operation time information (FIG. 3). Is.

Since the state controlled in this way and the default value corrected is stored as an intermittent operation mode together with various conditions such as weather conditions (S214, S224), when wastewater treatment is performed under the same conditions, the wastewater treatment is performed. It is also possible to read the past operation mode in the default setting and determine the operation mode. In addition, by collecting these data throughout the year, it is possible to set standard intermittent operation time information as a whole.

In this way, regardless of which control method is used, by measuring the dissolved oxygen concentration and pH value, it is possible to achieve an aeration state that is just right in the aeration tank, and to perform appropriate treatment while adjusting the activity of microorganisms. Water can be discharged. Further, in any case, since the blower is operated intermittently and the operation stop time is provided, the power consumption due to the movement of the blower can be reduced. In addition, since the blower does not operate continuously, it also contributes to a longer life.

A modified example of the above embodiment relating to the aeration system will be described. FIG. 5 shows an outline of the modified example. As shown in FIG. 2, in this modified example, the redox potential meter 15 is installed in the aeration tank 1 as an oxygen state measuring means. Since the redox potential meter 15 can measure from the manas potential to the positive potential, whether the water to be treated in the aeration tank 1 is in the oxidized state (positive potential) or in the reduced state (negative potential), these. Both can be measured. Therefore, it can be determined that it is aerobic in the oxidized state, anaerobic in the reduced state, and it can be determined that it is in an over-aerated state when the positive potential exceeds 150 mV. In the modified example, the pH sensor is not provided.

As described above, the control method when measuring the state of the water to be treated by the redox potential meter 15 refers to the measured value (ORP value) of the redox potential as shown in FIG. 6 or FIG. .. FIG. 6 is a diagram showing a flow of intermittent operation control of the blower based on the standard intermittent operation time information, and is a modification of the control method shown in FIG. As shown in this figure, when the ORP value is -100 mV or more (S106), it is further determined whether or not it exceeds +150 mV (S108), and if +150 ≦, it is regarded as a normal value. If it exceeds, it is determined that the air is over-aerated, and it is determined whether or not the air is increasing (S111), and either the ratio of the operating time or the time of one cycle is changed (S112, S113).

On the other hand, when the ORP value is lower than -100 mV (S106), it is determined that the oxygen supply amount is decreasing, and depending on whether or not the oxygen supply amount is further decreasing (S120), the ratio of the operation time or one cycle is also determined. Any one of the times of (S121, S122) is to be changed. The lower limit of the oxygen supply state is set to -100 mV because when aerobic bacteria are actively active, they may be in a reduced state even if the oxygen supply amount is sufficient. This lower limit value Can be set as appropriate. The upper limit can be set as appropriate, but if it exceeds 150 mV, it is clearly over-aeration, so the value around it should be used as a guide.

Further, FIG. 7 illustrates a method of deriving a suitable intermittent operation time from the default setting without providing standard intermittent operation time information, and is a modification of the control method shown in FIG. Also in FIG. 7, similarly to the above (in the case of FIG. 6), oxygen deficiency or over-aeration is determined based on the lower and upper limits of the ORP value by the redox potential meter 15 (S205, S207), and the operation time is determined. Either the ratio of S212 or the time of one cycle is changed (S212, S213, S221, S222).

The present embodiment is as described above, but the above embodiment shows an example of the present invention, and the present invention is not intended to be limited to these embodiments. Therefore, it is possible to make various changes and add other elements to each element in the above embodiment.

For example, in the control method in the control unit, when determining the intermittent operation mode, the intermittent operation state may be set from the value obtained by measuring the flow rate of the drainage in advance. That is, in the control method based on the standard intermittent operation time information illustrated in FIG. 3 or FIG. 6, the planned flow rate information is assumed to be included in the standard intermittent operation time information, and is further shown in FIG. 8 (a). As described above, the intermittent operation mode corresponding to the input of the flow rate may be selected and determined (S103) by inputting the flow rate (S130).

Similarly, in the default set intermittent operation mode illustrated in FIG. 4 or 7, as shown in FIG. 8 (b), the basic flow rate is set in the default information (S202), and the flow rate input (S202). According to S230), when the flow rate is larger than the basic flow rate (S231), the operation time with respect to the stop time is lengthened (S232), and conversely, when the flow rate is smaller than the basic flow rate (S233), the stop time with respect to the operation time is extended. By prolonging the period (S234), a suitable air-exposed state can be obtained. At this time, the operation time with respect to the stop time may be lengthened, or the stop time with respect to the operation time may be lengthened due to a change in the relative ratio (the time per cycle is constant), or only the time to be lengthened. It may be simply lengthened (the time per cycle also increases).

Further, the flow rate input (S130, S230) may be executed every time the time progresses (for example, every hour). This makes it possible to change the initial intermittent operation mode according to the change in the flow rate and then make detailed settings according to the degree of the dissolved oxygen concentration or the hydrogen ion concentration.

As a method of wastewater treatment, by using the aeration system described above, the aeration state based on the above-mentioned control method is continued, and as a result, the wastewater can be treated in a suitable state. Is. In this case, since the blower 2 supplies oxygen to the aeration tank without excess or deficiency while repeating intermittent operation, effective processing can be realized with low power consumption. Further, as a modification of the wastewater treatment method, a plurality of aeration tanks having the above configuration may be provided and the treatment with aerobic bacteria may be repeated repeatedly, or a plurality of sedimentation tanks 5 may be provided to repeatedly perform solid-liquid separation. .. Further, a treatment tank using anaerobic bacteria may be provided to include a denitrification step.

1 Aeration tank (treatment tank)
2 Blower 3 Control unit 4 Inflow tank (sedimentation tank)
5 Sedimentation tank (discharge tank)
11 Air diffuser 12 Air supply tube 13 Dissolved oxygen concentration meter (DO concentration meter)
14 Flowmeter 15 Redox potential meter 31 Timer 32 Calendar 33 Storage unit 34 Calculation unit 35 Output unit 51 pH sensor 61 Thermometer A Aeration system B Wastewater treatment equipment

Claims (6)

An aeration tank, a blower for supplying air into the aeration tank, an inflow tank for temporarily storing wastewater and flowing it into the aeration tank, and an discharge tank into which the treated water treated in the aeration tank flows. In the activated sludge method wastewater treatment facility equipped with
A control unit for controlling the operation time and the stop time of the blower in order to operate the blower intermittently is provided.
The aeration tank includes a dissolved oxygen concentration meter that measures the dissolved oxygen concentration of the wastewater inside the aeration tank.
The discharge tank is provided with a pH measuring means for detecting the hydrogen ion concentration in the treated water.
The control unit is divided into a plurality of types according to a calendar function and a clock function, a processing date and a processing time, and a plurality of standard intermittent operations formed by the operating time and the stopping time of the blower and the time per cycle thereof. Equipped with a storage unit that stores time information
The control unit selects the processing date specified by the calendar function and the clock function from the standard intermittent operation time information and the standard intermittent operation time information matching at the time of processing to control the operating state of the blower , and the dissolution. Ri Monodea to modify any or all of the elements forming the standard intermittent operation time information in accordance with the detected value by the measured value and the pH measuring device according oximeter, corrected by the detection value of the pH measuring means , aeration systems in wastewater treatment facilities measured by the dissolved oxygen concentration meter, characterized in der Rukoto what is controlled to run when the predetermined or more. The standard intermittent operation time information is set based on a major division according to the distinction between summer, winter and spring / autumn, a middle division according to the distinction between weekdays and holidays, and a subdivision that distinguishes 24 hours every hour. The aeration system in the wastewater treatment facility according to claim 1. The aeration system in the wastewater treatment facility according to claim 1 or 2 , wherein the operating time and the stopping time of the blower are in the range of 15 seconds to 7200 seconds for one cycle. The flow rate measuring means for measuring the inflow amount of the wastewater flowing from the inflow tank to the aeration tank is further provided, and the control unit further includes the standard intermittent according to the inflow amount of the wastewater measured by the flow rate measuring means. The aeration system in a wastewater treatment facility according to any one of claims 1 to 3, which is controlled to modify any or all of the elements forming the operating time information. A wastewater treatment method using the aeration system according to any one of claims 1 to 3, wherein the control unit selects standard intermittent operation time information, and the measured value by the dissolved oxygen concentration meter and the pH measuring means. It is characterized in that any or all of the elements forming the standard intermittent operation time information are modified according to the detected value by, and the operating state of the blower is controlled based on the modified standard intermittent operation time information. Wastewater treatment method. The wastewater treatment method using the aeration system according to claim 4, wherein the control unit selects standard intermittent operation time information, and the measured value by the dissolved oxygen concentration meter, the detected value by the pH measuring means, and the said. Any or all of the elements forming the standard intermittent operation time information are modified according to the inflow amount of wastewater measured by the flow rate measuring means, and the operating state of the blower is modified based on the modified standard intermittent operation time information. A wastewater treatment method characterized by controlling.

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