JP6550212B2 - Waste water treatment apparatus and waste water treatment method - Google Patents

Description

  The present invention relates to a sewage treatment method and a sewage treatment apparatus for microbially treating organic pollutants contained in sewage.

Examples of methods for treating sewage such as domestic wastewater include those using microorganisms. In this waste water treatment method, for example, once the waste water is stored in the adjustment tank, it is sent to the aeration tank for aeration, and then the activated sludge is separated by sedimentation in the sedimentation tank to release the supernatant water (for example, Patent Document 1) reference). Such a waste water treatment method is adopted in a waste water treatment apparatus installed on a highway, and conventionally, the operation time of a blower for sending air to an aeration tank has been set by a timer. However, in the sewage treatment apparatus installed on an expressway, the inflow of sewage fluctuates significantly due to busy season, consecutive holidays, day of the week, event, season, weather, closing, and so on. For example, in sewage treatment equipment installed on expressways, the maximum inflow of sewage per day per year is 540m ³ / day, the minimum inflow is 46m ³ / day, and the average inflow is 104m ³ / day It fluctuates greatly. Moreover, while the inflow of sewage on weekdays is 90m ³ / day to 100m ³ / day on average, the inflow of sewage on weekends is 50m ³ / day to 100m ³ / day on average on weekdays It has increased.

  Therefore, in the driving | operation of the air blower by a timer, it is difficult to respond | correspond to inflow fluctuation | variation, and excess and deficiency had arisen in the amount of air. As a result, when the amount of air is excessive, the sludge is dismantled and becomes fine, mixed with the discharged water and discharged, and the quality of the discharged water decreases, or the blower is operated wastefully, which results in consumption There is also a problem that waste of power occurs. In addition, when the amount of air is insufficient, there is also a problem that dirt is taken into the sludge and excess sludge is increased. Furthermore, when the amount of air is insufficient, scum in which the sludge rots is generated, and there is a problem that it is necessary to treat it. In addition, conventionally, this has been dealt with by predicting the inflow of dirty water at the time of inspection and changing the setting of the timer, but it is difficult to cope in real time, and to cope with fluctuations in detail, There is also a problem that the operation takes time since the setting must be changed frequently.

Unexamined-Japanese-Patent No. 5-185087 gazette

  The present invention is made based on such a problem, and an object of the present invention is to provide a waste water treatment apparatus and a waste water treatment method which can easily cope with fluctuation of the amount of inflow of waste water.

  The waste water treatment apparatus of the present invention purifies waste water using activated sludge, and contains an aeration tank for containing sewage with activated sludge and aerating the air, a blower for sending air to the aeration tank, and the aeration tank Operation of the blower when the pH measurement means for measuring the pH value of the waste water in the sample and the pH measurement value measured by the pH measurement means become equal to or more than the first set value within the range of pH 6.4 to pH 7.0. To start feeding air into the aeration tank, and the pH measurement value measured by the pH measurement means is within the range of pH 5.8 or more and pH 6.4 or less and 0.3 or more smaller than the first set value The air conditioner is provided with a pH reference operation control means for controlling so as to stop the operation of the blower and to stop the feeding of air into the aeration tank when the value becomes equal to or less than the second set value.

  The wastewater treatment method according to the present invention is a method for purifying wastewater using activated sludge by storing wastewater with activated sludge in an aeration tank and supplying air with a blower to aerate the wastewater, and the wastewater in the aeration tank is treated. When the measured pH value becomes equal to or higher than the first set value within the range of pH 6.4 to pH 7.0, the operation of the blower is started to feed air to the aeration tank. Start and stop the operation of the blower when the pH measurement value falls within the range of pH 5.8 or more and pH 6.4 or less and the second set value which is 0.3 or more smaller than the first set value. And a pH-based operation control procedure that controls to stop the feeding of air into the aeration tank.

  According to the present invention, the pH value of the dirty water in the aeration tank is measured, and the operation of the blower is started when the pH measurement value becomes equal to or more than the first set value by the pH reference operation control means. Since the operation of the blower was stopped when it became lower than the set value, when the alkaline wastewater including human waste flows in and the pH value rises, the feeding of air to the aeration tank is started, and the ammonia contained in the human waste When the pH value decreases due to the nitrification (oxidation) of the volatile nitrogen, the feed of air to the aeration tank can be stopped. Therefore, the inflow fluctuation of the sewage can be easily coped with, and the ratio of the inflow BOD / the amount of air (the required amount of oxygen) can be made within a predetermined range, and the generation of excess or deficiency in the air amount can be suppressed.

  Therefore, the amount of air becomes excessive, and the sludge can be finely dismantled, mixed with the discharged water and flowed out, so that the deterioration of the discharged water quality can be suppressed. In addition, the blower can be operated efficiently, and power consumption can be reduced. Furthermore, it is also possible to suppress an increase in excess sludge due to the lack of air volume. In addition, it is possible to suppress the generation of scum in which the sludge rots due to excess or deficiency of the air amount, and it is possible to reduce the time and effort of the treatment operation. Furthermore, it is not necessary to change the setting of the operation control timer, and it is possible to reduce the time and effort of work.

  In particular, if the present invention is used by a large number of unspecified customers, such as service areas installed on expressways, and facilities where the inflow fluctuation of the sewage is severe, it is possible to easily cope with the inflow fluctuation of the sewage. Because you can, you can get higher effects.

  Also, if control based on the pH value and control based on the operation control timer are used together to adjust those controls, control based on the pH value is performed when the amount of waste water is large, and operation control is performed when the amount of waste water is small Control by a timer can be performed, and it can respond easily by the inflow fluctuation of sewage.

It is a figure showing the composition of the waste water treatment apparatus concerning the 1 embodiment of the present invention. It is a figure explaining the waste water treatment procedure by the waste water treatment apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing the configuration of a sewage treatment apparatus 1 according to an embodiment of the present invention. FIG. 2 is a view for explaining the waste water treatment procedure by this waste water treatment apparatus 1. This waste water treatment apparatus 1 can be preferably used in facilities with a large inflow fluctuation of the waste water M1, such as a service area or a parking area installed on an expressway, which is used by many unspecified users.

  The waste water treatment apparatus 1 temporarily stores, for example, the waste water M1, and adjusts the flow rate of the waste water M1 and the fluctuation of the quality of the water, the aeration tank 20 which contains the waste water M1 with the activated sludge and aerates it. It has a blower 30 for feeding air into the tank 20, and a settling tank 40 for settling sludge M3 from the aerated waste water M2 and separating it into sludge M3 and supernatant water M4. In the adjustment tank 10, for example, water level sensors 11WH and 11WL for detecting the water level and the adjustment pump 12 are disposed. The water level sensor 11WH detects a high water level for activating the adjustment pump 12, and the water level sensor 11WL detects a low water level for stopping the adjustment pump 12. The adjustment tank 10 and the aeration tank 20 are connected by, for example, a pipe 13, and a flow rate meter 14 is disposed in the pipe 13, for example. For example, when it is detected by the water level sensor 11WH that the water level of the sewage M1 is higher than a predetermined reference water level, the sewage M1 of the adjustment layer 10 is made to flow into the aeration tank 20 through the piping 13 by the adjustment pump 12. ing. It is preferable that the piping 13 be disposed so that the dirty water M1 flows in from the upper side of the aeration tank 20.

  The aeration tank 20 includes, for example, a first aeration tank 20A connected by a pipe 21 and a second aeration tank 20B. For example, the pipe 21 can be opened and closed by the valve 22. When the amount of treated sewage is large, the valve 22 is opened to use the first aeration tank 20A and the second aeration tank 20B, and the amount of treated sewage is small. Can be adjusted so that the valve 22 is closed and only the first aeration tank 20A is used. Although FIG. 1 shows the case where the aeration tank 20 includes two units of the first aeration tank 20A and the second aeration tank 20B, in a place where the amount of treated sewage is small, only the first aeration tank 20A is configured Alternatively, three or more units such as the third aeration tank may be provided in places where the amount of waste water treated is large.

  For example, a blower pipe 31 connected to a blower 30 is disposed in the inside of the aeration tank 20, specifically, in the first aeration tank 20A and the second aeration tank 20B. The aeration tank 20, specifically, the first aeration tank 20A and the second aeration tank 20B, and the settling tank 40 are connected by, for example, a pipe 23.

In the aeration tank 20, for example, activated sludge is used to purify the sewage M1. The wastewater M1 contains, for example, organic soil and ammonia (NH ₄ ⁺ ). For example, the reaction formula is shown below using glucose (glucose; C ₆ H ₁₂ O ₆ ) as the organic substance. It is purified by anabolism, catabolism and internal respiration.
Anabolic C ₆ H ₁₂ O ₆ (organic matter) + NH ₃ + O ₂
→ C ₅ H ₇ NO ₂ (new sludge) + CO ₂ + 4 H ₂ O
Catabolism C ₆ H ₁₂ O ₆ (organic matter) + 6O ₂ → 6CO ₂ + 6H ₂ O + heat Internal respiratory action C ₅ H ₇ NO ₂ (sludge) + 7O ₂ → 5CO ₂ + 3H ₂ O + HNO ₃

In the aeration tank 20, when the amount of air is insufficient, the assimilation action increases, the catabolism action and the internal respiration action decrease, and the excess sludge increases. On the other hand, when the amount of air is appropriate, catabolism and internal respiration increase and sludge decreases. Therefore, it is important to control the amount of air appropriately. The wastewater M1 flowing into the aeration tank 20 exhibits weak alkalinity with a pH value of about pH 7.5 to about pH 8.5 because it contains ammonia (NH ₄ ⁺ ), but it is purified in the aeration tank 20 As a result of nitrification (oxidation) and oxygen binding by anabolic action and internal respiratory action, the nitrogen state changes as shown below, and the pH value drops, for example, from pH 6.2 to about pH 6.8. That is, the internal respiratory action can be confirmed by the decrease in pH value.
NH ₄ ⁺ (ammoniacal nitrogen) → NO ₂ ⁻ (nitrite nitrogen) → NO ₃ ⁻ (nitrate nitrogen)

  In the waste water treatment apparatus 1, pH measuring means 50 for measuring the pH values of the dirty water M 1 and M 2 in the aeration tank 20 is disposed in the aeration tank 20, and the pH measurement value measured by the pH measuring means 50 is used. A control unit 60 that controls the operation of the blower 30 is provided. The pH measuring means 50 is preferably disposed, for example, in the vicinity of the outlet of the aeration tank 20. The control unit 60 controls, for example, a pH-based operation control unit 61 that controls the operation of the blower 30 based on the pH measurement value measured by the pH measurement unit 50, and an operation control timer that controls the blower 30 to operate according to the setting conditions. It is preferable to have 62 and the operation adjustment means 63 which adjusts control of pH reference operation control means 61 and the operation control timer 62.

  The pH reference operation control means 61 starts the operation of the blower 30, for example, when the pH measurement value measured by the pH measurement means 50 becomes the first set value or more within the range of pH 6.4 or more and pH 7.0 or less. Start sending air to the aeration tank 20, and the pH measurement value measured by the pH measurement means is within the range of pH 5.8 or more and pH 6.4 or less and 0.3 or more smaller than the first set value When it becomes below 2 setting values, it is constituted so that operation of fan 30 may be stopped and sending of air to aeration tank 20 may be stopped. The first set value is more preferably in the range of pH 6.5 to pH 7.0, and the second set value is in the range of pH 6.0 to pH 6.4 and less than the first set value. It is more preferable to reduce by 3 or more.

  The operation control timer 62 is configured to operate, for example, at set intervals of the blower 30 for a set time.

  The operation adjustment unit 63 operates the blower 30, for example, when at least one of the pH reference operation control unit 61 and the operation control timer 62 controls the blower 30, and the pH reference operation control is performed. When both the means 61 and the operation control timer 62 are controlling to stop the operation of the blower 30, the operation of the blower 30 is stopped. That is, for example, when at least one of the pH reference operation control unit 61 and the operation control timer 62 instructs the operation of the blower 30, the operation adjustment unit 63 instructs the operation and both of them instruct the operation stop. At the same time, it is configured to instruct to stop the operation.

  In addition, the operation adjustment unit 63 starts the operation of the blower 30, for example, when at least one of the pH reference operation control unit 61 and the operation control timer 62 controls to start the operation of the blower 30, and When only one of the pH reference operation control means 61 and the operation control timer 63 controls the blower 30 to operate, when one of the pH reference operation control means 61 and the operation control timer 63 is controlled to stop the operation of the blower 30, When the operation is stopped and both of the pH reference operation control means 61 and the operation control timer 62 control the blower 30 to operate, the pH reference operation control means 61 stops the operation of the blower 30. It may be configured to stop the operation of the blower 30 when it is controlled. That is, the operation adjustment unit 63 starts operation when, for example, at least one of the pH reference operation control unit 61 and the operation control timer 62 instructs to start the operation of the blower 30, the pH reference operation control unit 61. When only one of the operation control timers 63 instructs the operation of the blower 30, the operation of the blower 30 is stopped when one of the operation control timers 63 instructs the operation stop, and both indicate the operation of the blower 30. In this case, priority may be given to the instruction of the pH reference operation control means 61, and the operation of the blower 30 may be stopped when the pH reference operation control means 61 instructs the stop of the operation.

  The sewage treatment apparatus 1 is also connected, for example, with a settling tank 40 and a pipe 41, and a disinfecting tank 70 for disinfecting the supernatant water M4 separated in the settling tank 40, and the disinfecting tank 70 and a pipe 71 are connected and disinfected And a discharge tank 80 for discharging the supernatant water M1. The settling tank 40 is also provided with a pipe 42 for returning a part of the separated sludge M3 to the aeration tank 20 and carrying out a part of the excess sludge M3. In the pipe 42, a sludge measuring device 43 and a sludge return device 44 are disposed. For example, a discharge pump 81 is disposed in the discharge tank 80.

  The waste water treatment apparatus 1 performs waste water treatment, for example, as follows. The waste water M1 first flows into the adjustment tank 10, and flows into the aeration tank 20 by the adjustment pump 12 when the water level of the waste water M1 in the adjustment tank 10 becomes higher than a predetermined reference water level. The sewage M1 accommodated in the aeration tank 20 is aerated by the air sent by the blower 30, and is purified by activated sludge. At that time, the blower 30 is controlled as follows.

  First, the pH value of the dirty water M1, M2 in the aeration tank 20 is measured by the pH measuring means 50, and the pH measured value is within the range of pH 6.4 or more and pH 7.0 or less by the pH reference operation control means 61, for example. When the first set value is reached, operation of the blower 30 is started to start air feeding into the aeration tank 20, and the pH measurement value is within the range of pH 5.8 or more and pH 6.4 or less and the first When it becomes below the 2nd set value which is 0.3 or more smaller than the set value, it controls so that operation of fan 30 is stopped and sending of air to aeration tank 20 is stopped (pH standard operation control procedure).

Thereby, in the waste water treatment apparatus 1, for example, as shown in FIG. 2, when the water level of the adjustment tank 10 rises, (1) the waste water flows into the aeration tank 20 by the adjustment pump 12, (2) the waste water M1. When the pH value in the aeration tank 20 rises due to ammonia (NH ₄ ⁺ ) contained in (3) the measured pH value becomes equal to or more than the first set value, (4) operation of the blower 30 by the pH reference operation control means 61 Is started, air is fed into the aeration tank 20, and (5) the pH value in the aeration tank 20 is lowered by the stirring. After that, when the water level in the adjustment tank 10 falls, (6) the adjustment pump 12 stops, and (7) the pH value in the aeration tank 20 decreases due to the nitrification (oxidation) of ammonia (NH ₄ ⁺ ) (8 The operation of the blower 30 is stopped by (9) pH reference operation control means 61 when the pH measurement value becomes equal to or less than the second set value.

  Further, it is preferable to control the operation of the blower 30 by using the operation control timer 62 in combination with the pH reference operation control means 61. The operation control timer 62 controls the blower 30 to operate for a set time, for example, at set intervals regardless of the inflow of the dirty water M1 (timer operation control procedure).

  The control by the pH reference operation control unit 61 (pH reference operation control procedure) and the control by the operation control timer 62 (timer operation control procedure) are adjusted by the operation adjustment unit 63 as follows. For example, when the blower 30 is controlled to be operated by at least one of the pH reference operation control procedure and the timer operation control procedure, the blower 30 is operated and the pH reference operation control procedure and the timer operation control procedure When both are controlled to stop the operation of the blower 30, the operation of the blower 30 is stopped.

  Further, when it is controlled to start the operation of the blower 30 by at least one of the pH reference operation control procedure and the timer operation control procedure, the operation of the blower 20 is started, and the pH reference operation control procedure and the timer operation When it is controlled to operate the blower 30 by only one of the control procedures, the operation of the blower 30 is stopped when it is controlled to stop the operation of the blower 30 by one of the control procedures, pH reference operation control When it is controlled to operate the blower 30 by both the procedure and the timer operation control procedure, the operation of the blower 30 is stopped when it is controlled to stop the operation of the blower 30 by the pH reference operation control procedure It may be adjusted to

  Thus, in the waste water treatment apparatus 1, the blower 30 is operated by the control of the pH reference operation control means 61 when the amount of the sewage M1 is large, and the blower 30 is operated by the control of the operation control timer 62 when the amount of the sewage M1 is small. By doing this, it is possible to cope with the inflow fluctuation of sewage.

  The contaminated water M2 thus purified is sent to the settling tank 40, and the sludge M3 is separated by sedimentation in the settling tank 40, and the supernatant water M4 is sent to the disinfection tank 70 and disinfected, and then sent to the discharge tank 80. And is discharged by the discharge pump 81. Also, a part of the separated sludge M3 is returned to the aeration tank 20, and a part of the excess sludge M3 is carried out.

  When the sewage treatment apparatus 1 of the present embodiment is installed in the service area of an expressway and sewage treatment is performed for one year, the BOD of the discharge water is about 1 mg / l to 5 mg / l, and the visibility is through the period There is no change with 30 degrees or more, and it turned out that it is a problem-free water quality.

  In addition, the operation time of the blower 30 from August to March of the following year when the waste water treatment of the present embodiment is performed and the power consumption of the waste water treatment apparatus 1 and the operation control timer The operating time of the blower from August to March of the following year when sewage was treated with the conventional sewage treatment apparatus under control was compared with the power consumption of the sewage treatment apparatus. The results are shown in Tables 1 and 2. Moreover, when the conventional waste water treatment apparatus in which the blower is controlled only by the operation control timer and the sludge withdrawal amount in one year when the waste water treatment with the waste water treatment apparatus 1 of the present embodiment is performed 1 The annual sludge withdrawal was compared. The results are shown in Table 3. In the operation control of the blower 30 in the waste water treatment apparatus 1 of the present embodiment, the first set value is set to pH 6.7, and the second set value is set to pH 6.4. Moreover, the operating time of the blower in the conventional waste water treatment apparatus, the consumed power amount of the waste water treatment treatment, and the sludge withdrawal amount are the same in the same service area where the waste water treatment apparatus 1 of the present embodiment is installed. It is the value which averaged for the past 3 years before installing the sewage treatment equipment 1 of the above.

  As shown in Table 1, according to the waste water treatment apparatus 1 of the present embodiment, the operating time of the blower 30 is 38% in August, 14% in September, and so on, as compared with the conventional waste water treatment apparatus. We were able to reduce 30% to 45%. In addition, as shown in Table 2, according to the waste water treatment apparatus 1 of the present embodiment, the power consumption is reduced by 32% in August, 22% in September, and around 30% thereafter. I was able to. Furthermore, as shown in Table 3, the sludge removal amount could be reduced by 25.6% according to the wastewater treatment device 1 of the present embodiment. That is, according to the waste water treatment apparatus 1 of the present embodiment, it has been found that the blower can be operated efficiently, power consumption can be reduced, and excess sludge can be reduced.

  As described above, according to the present embodiment, the pH value of the dirty water in the aeration tank 20 is measured, and the operation of the blower 30 is started when the pH measurement value becomes equal to or more than the first set value by the pH reference operation control means 61. Since the operation of the blower 30 is stopped when the pH measurement value falls below the second set value, the air to the aeration tank 30 flows when the pH value rises due to the inflow of alkaline sewage M1 containing human waste. The feeding of air into the aeration tank 30 can be stopped when the pH value is lowered due to the nitrification (oxidation) of the ammoniacal nitrogen contained in the human waste. Therefore, the inflow fluctuation of the dirty water M1 can be easily coped with, and the ratio of the inflow BOD to the air amount (necessary oxygen amount) can be set within a predetermined range, and the generation of excess or deficiency of the air amount can be suppressed.

  Therefore, the amount of air becomes excessive, and the sludge M3 is finely disassembled, mixed with the discharged water and discharged, and it is possible to suppress the decrease in the discharged water quality. Further, the blower 30 can be operated efficiently, and power consumption can be reduced. Furthermore, it is also possible to suppress an increase in excess sludge due to the lack of air volume. In addition, the generation of scum due to excess or deficiency of the air amount can be suppressed, and the time and effort of the processing operation can be reduced. Furthermore, it is not necessary to change the setting of the operation control timer, and it is possible to reduce the time and effort of work.

  In particular, if it is used by a large number of unspecified customers, such as service areas installed on expressways, and used in facilities where the inflow fluctuation of sewage is severe, the inflow fluctuation of sewage can be easily coped with, Higher effects can be obtained.

  In addition, if the control by the pH reference operation control means 61 and the control by the operation control timer 62 are used together and the control thereof is adjusted by the operation control means, the pH reference operation control means 61 when the amount of waste water M1 is large. When the amount of waste water M1 is small, the control by the operation control timer 62 can be performed, and it is possible to easily cope with the inflow fluctuation of the waste water M1.

  The present invention has been described above by the embodiment. However, the present invention is not limited to the above embodiment, and can be variously modified. For example, in the above-mentioned embodiment, although each component was concretely explained, it is not necessary to have all the components and may have other components.

  DESCRIPTION OF SYMBOLS 1 ... Sewage treatment apparatus, 10 ... Adjustment tank, 11WH, 11WL ... Water level sensor, 12 ... Adjustment pump, 13 ... Piping, 14 ... Flow meter, 20 ... Aeration tank, 20A ... 1st aeration tank, 20B ... 2nd aeration Tank, 21: Piping, 22: Valve, 23: Piping, 30: Blower, 31: Blower, 40: Sedimentation tank, 41, 42: Piping, 43: Sludge weighing device, 44: Sludge return device, 50: pH measurement Means, 60: control unit, 61: pH reference operation control means, 62: operation control timer, 63: operation adjustment means, 70: disinfection tank, 71: piping, 80: discharge tank, 81: discharge pump

Claims (2)

A sewage treatment system that purifies sewage using activated sludge, used in facilities installed on expressways,
An aeration tank that contains waste water with activated sludge and aerates;
A blower for feeding air into the aeration tank;
PH measuring means for measuring pH value of the sewage in the aeration tank,
When the pH measurement value measured by the pH measurement means becomes equal to or higher than the first set value within the range of pH 6.4 to pH 7.0, the operation of the blower is started to feed air into the aeration tank. When the pH measurement value measured by the pH measurement means falls below a second set value within the range of pH 5.8 or more and pH 6.4 or less and 0.3 or more smaller than the first set value, PH reference operation control means for controlling so as to stop the operation of the blower and to stop the feeding of air to the aeration tank;
An operation control timer that controls the blower to operate for a set time at set intervals;
When at least one of the pH reference operation control means and the operation control timer is controlling to operate the blower, the blower is operated, and the pH reference operation control means and the operation control timer when both are controlled so as to stop the operation of the blower, sewage treatment apparatus characterized by comprising a driving adjusting means for by Uni adjustment you stop the operation of the blower. A sewage treatment method for purifying sewage using activated sludge by storing sewage in an aeration tank together with activated sludge in a facility installed on a highway, and aeration by sending air with a blower.
The pH value of the dirty water in the aeration tank is measured, and when the measured pH value becomes equal to or more than the first set value in the range of pH 6.4 or more and pH 7.0 or less, the operation of the blower is started to When feeding of air into the aeration tank is started, and the measured pH value is within the range of pH 5.8 or more and pH 6.4 or less and is equal to or less than the second set value smaller than the first set value by 0.3 or more, A pH-based operation control procedure of controlling to stop the operation of the blower and to stop the feeding of air to the aeration tank;
A timer operation control procedure of controlling the blower to operate for a set time at set intervals by an operation control timer;
When the blower is controlled to be operated by at least one of the pH reference operation control procedure and the timer operation control procedure, the blower is operated, and the pH reference operation control procedure and the timer operation control both procedures when being controlled so as to stop the operation of the blower, sewage treatment method which comprises a driving adjustment procedure of due to Suspend urchin adjust the operation of the blower.

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