JP4620391B2 - Sewage treatment equipment - Google Patents

Description

  The present invention relates to a sewage treatment apparatus using a floating microorganism treatment method that performs intermittent aeration.

  The sewage treatment equipment using the floating microbial treatment method that performs intermittent aeration includes the sewage treatment equipment by the oxidation ditch (OD) method, JARUS-XIV type (continuous inflow-intermittent aeration), JARUS-XV type (intermittent inflow- There is an agricultural village drainage treatment device of intermittent aeration.

  In such a sewage treatment apparatus, the sewage treatment apparatus using the oxidation ditch (OD) method uses a reaction tank of an endless circulation channel, generates a water flow by an aeration rotor, and circulates sewage containing air and activated sludge to agitate. I'm going to do it.

  Then, in the reaction tank of the circulation channel, in a state where oxygen is supplied by aeration (aerobic), the nitrification reaction that oxidizes ammonia nitrogen to nitrate nitrogen and the nitrate nitrogen generated by the nitrification reaction are dissolved oxygen. Purification is performed by a denitrification reaction that is reduced to nitrogen gas in the absence (oxygen-free) state.

  In sewage treatment equipment based on the OD method, which is originally designed on the assumption of low-load operation, in many cases, much less sewage flows than the designed treatment capacity. Due to excessive supply, the entire reaction tank tends to be aerobic. In particular, when the water channel of the reaction tank is short, it is difficult to create an oxygen-free state necessary for denitrification. For this reason, the aeration apparatus is repeatedly operated and stopped, and intermittent aeration is performed to create an aerobic and anoxic state.

  By the way, the conventional intermittent aeration operation pattern is an ON / OFF operation created based on the experience and intuition of the treatment plant manager, and once the operation pattern is created, it does not change for a certain period (for example, several days) Since the removal of ammonia nitrogen is preferentially considered, over-aeration is set for the average inflow load.

  On the other hand, for the removal of excess sludge, a timer is created in consideration of the capacity of the sludge concentration tank, the extraction time of the concentrated sludge, the sludge transport time, and the like. Moreover, since the return sludge is returned to the reaction tank, untreated water may flow into the sedimentation tank when aeration is stopped. In order to prevent this, a timer is usually set so that a return is returned when aeration is performed. In addition, the surplus sludge / returned sludge is also extracted based on the experience of the manager.

  Although the conventional technology has been described above by taking the OD method as an example, the fact that the aeration operation pattern is determined based on the experience and intuition of the manager is common to all conventional sewage treatment apparatuses. .

  However, when aeration is performed by a timer or the like set based on the experience and intuition of the manager as described above, it is not possible to appropriately cope with fluctuations in the inflow load, and it is not always possible to obtain good discharged water quality.

  The present invention has been made in view of the above points, and automatically performs appropriate intermittent aeration, constantly improving the removal efficiency of organic matter and nitrogen, and reducing the amount of electricity consumed while stabilizing the quality of the treated water obtained. Sewage treatment equipment that can reduce the amount of sludge from the settling tank stably in response to the aeration time and the aeration time that are uncertain due to automatic intermittent aeration. Is intended to provide.

Thus, the gist of the present invention resides in a sewage treatment apparatus having the following configuration.
(1) Provided with an oxygen requirement calculation unit and an aeration control unit, air is sent to the reaction tank based on the integrated value of the oxygen requirement, and the sewage and activated sludge flowing into the reaction tank are aerated to contaminate the sewage while biochemically removed by activated sludge, the precipitated sludge in the settling tank, a portion is returned to the reaction vessel, the rest Te sewage treatment apparatus odor when taken to discharge the excess sludge, the oxygen required The amount calculation unit includes an inflowing oxygen requirement (or _-inflow ) calculation unit, an endogenous oxygen requirement (or- _endogenous ) calculation unit, a supply oxygen amount (os) calculation unit, and a total oxygen requirement (or) calculation. The _inflowing oxygen requirement (or _-inflow ) calculating unit measures the inflow water SS (or turbidity or transparency) with a sensor, and measures the inflow SS (or turbidity or transparency) measured in advance. ) Correlation of measured values with inflow BOD and Kjeldahl nitrogen The inflow BOD concentration and the Kjeldahl nitrogen concentration are calculated using the unit, and the calculated inflow BOD concentration and the Kjeldahl nitrogen concentration and the treated water amount measured by the inflow water meter or the discharge water meter (or the operation time of the inflow pump, etc.) The inflowing oxygen required amount is calculated from the product of the calculated inflowing amount), and the endogenous oxygen requirement (or- _endogenous ) calculation unit measures MLSS with a sensor to detect oxygen related to endogenous respiration. The required amount is calculated, the supplied oxygen amount (os) calculation unit calculates the amount of oxygen supplied by aeration, and the total oxygen required amount (or) calculation unit requires the above inflowing oxygen. The numerical value obtained by subtracting the supply oxygen amount from the total amount of oxygen and the amount of endogenous oxygen is calculated and integrated at regular time intervals, and the aeration control unit is the product of the total oxygen requirement calculation unit. It controls the operation of the aeration equipment based on the value OR, and starts aeration when the integrated value OR exceeds the aeration start set value, and automatically stops aeration when it falls below the aeration stop set value. The sewage treatment device is designed to control intermittent aeration, and after the sludge is extracted from the subsequent sludge concentration tank, the inflow sewage is supplied to the reaction tank, and when the aeration equipment starts operation, The settling timer is set to ON, and the excess sludge is drawn out with the draw time set when the settling timer is up, but the settling timer for turning off the excess sludge is turned on until the drawout is completed. A sewage treatment device that pulls out the returned sludge when the aeration equipment is in operation and at a certain time after the aeration is stopped.

(2) A processing device capable of controlling the amount of aeration air or the number of rotations of the aeration equipment is used. When the aeration time of the day exceeds the upper limit of the aeration time and when the aeration time lower limit is exceeded, the amount of aeration air or the number of rotations is set. The sewage treatment apparatus according to (1), further including an aeration control unit capable of automatically adjusting an aeration air volume or a rotation speed so that an aeration time is controlled within an appropriate range by adjusting.

FIG. 1 is an explanatory diagram of the basic configuration of the present invention. Thus, in the above (1) to (2), the required amount of inflowing oxygen (or _-inflow ) is calculated by the following equations (1) and (2).

ここで、ｏｒ_{− 流入}は流入負荷であり、流入ＢＯＤの酸化及びケルダール窒素の硝化と脱窒に必要な酸素量である。Ｆは反応槽に流入する汚水の流量〔ｍ^３ ／Ｈｒ〕で、ｃは流入汚濁物質濃度〔Ｋｇ−Ｏ_２ ／ｍ^３ 〕である。流入汚水のＳＳとＢＯＤ及びケルダール窒素の相関を利用すると、次の式となる。

Here, or _{− inflow} is an inflow load, which is the amount of oxygen required for oxidation of the inflow BOD and nitrification and denitrification of Kjeldahl nitrogen. F is the flow rate [m ³ / Hr] of sewage flowing into the reaction tank, and c is the influent pollutant concentration [Kg-O ₂ / m ³ ]. When the correlation between SS, BOD and Kjeldahl nitrogen is used, the following equation is obtained.

ここで、Ｋ_ＳＳとＫ_ｃ は係数であり、ＳＳ_ｉｎは反応槽に流入する前の浮遊物濃度である。また、流入酸素必要量（ｏｒ_−流入）の経時変化例は、図３において線ａで示す通りである。

Here, K _SS and K _c are coefficients, and SS _in is the suspended matter concentration before flowing into the reaction vessel. Further, an example of the change over time of the inflowing oxygen required amount (or _-inflow ) is as shown by a line a in FIG.

Moreover, in said (1)-(2), calculation of endogenous oxygen required amount (or- _endogenous ) is performed by following Formula (3). This is calibrated after measuring the water temperature in the reaction vessel.

ここで、Ｋ_ＭＬは微生物の内生呼吸速度係数であり、水温によって変化する。Ｖ_Ａ は反応槽の好気ゾーン容積である。

Here, _KML is an endogenous respiration rate coefficient of microorganisms, and changes depending on the water temperature. V _A is the aerobic zone volume of the reactor.

  In (1) and (2) above, the supply oxygen amount (os) calculation unit calculates the amount of oxygen supplied by aeration as described above. The supplied oxygen amount is shown in FIG. It is obtained from the performance curve of the aeration apparatus shown.

  In (1) to (2) above, the total oxygen requirement (or) is calculated by subtracting the supplied oxygen amount from the sum of the inflowing oxygen requirement and the endogenous oxygen requirement as described above, and for a certain period of time. Integration is performed at intervals, which is expressed by the following equations (4), (5), and (6). Note that (or integrated value = OR).

  Next, or is integrated.

積分式を離散化すると、次のようになる。

When the integral formula is discretized, it becomes as follows.

Here, Δt is a constant time interval.
The change with time of the integral value is as shown by a line b in FIG.

Then, as indicated by lines b and c in FIG. 3, the aeration control unit controls the operation of the aeration equipment based on the integrated value OR. That is, since the supply oxygen amount is zero when aeration is stopped, OR is accumulated with the inflow of sewage. When the integrated value OR exceeds the aeration start OR set value, an operation command is issued to the aeration equipment. When the supplied oxygen amount os during aeration exceeds the total amount of the inflowing oxygen requirement (or _-inflow ) and the endogenous oxygen requirement (or _-endogenous ), the integrated value OR decreases. Aeration is stopped when it falls below a set value (for example, zero) of aeration stop. By repeating this, intermittent aeration is automatically performed.

  However, long-term continuous aeration and continuous stoppage may occur depending on the inflow load. Long-term continuous aeration deteriorates denitrification efficiency, and long-term continuous stoppage may adversely affect microorganisms that perform biological treatment. When the upper limit is exceeded, the aeration is forcibly stopped or operated.

  Further, when the supply amount of oxygen is constant, the aeration time is shortened if the aeration amount is large. Conversely, if the amount of aeration is small, the aeration time becomes longer. In general, in the case of intermittent aeration, it is necessary to balance aeration time and aeration stop time. Therefore, in the processing apparatus capable of controlling the aeration air volume or the rotation speed of the aeration equipment as described above, when the aeration time of the day exceeds the aeration time upper limit or when the aeration time lower limit is exceeded, By adjusting the rotation speed, the aeration air volume or the rotation speed can be automatically adjusted so that the aeration time is controlled within an appropriate range.

  On the other hand, in many sewage treatment apparatuses that perform intermittent aeration, extraction of return sludge and excess sludge is controlled by a timer in accordance with the timing of aeration. At this time, normally, similarly, a drawing schedule is determined in accordance with preset aeration by a timer or the like. This schedule will be described with reference to an oxidation ditch (OD) sewage treatment apparatus having the sludge concentration facility shown in FIG. 4 as an example.

  In FIG. 4, 100 is a reaction tank of an endless circulation channel, which causes a water flow by the aeration rotor 101, and circulates and stirs the sewage containing air and activated sludge. Reference numeral 102 denotes a flow path of sewage to the reaction tank 100. 103 is a precipitation tank, 104 is a passage connecting the reaction tank 100 and the precipitation tank 103, and 105 is a passage for discharging the supernatant water of the precipitation tank 103. 106 is a sludge return path connecting the bottom of the sedimentation tank 103 and the reaction tank 100, 107 is an excess sludge extraction path connected to the middle part of the sludge return path 106, and 108 is sludge concentration connected to the excess sludge extraction path 107. A tank 109 is a concentrated sludge extraction path connected to the bottom of the sludge concentration tank 108. Reference numerals 110, 111, 112, and 113 denote pumps.

Normally, when sewage or return sludge flows into the reaction tank 100, the aqueous solution in the reaction tank 100 flows into the precipitation tank 103 in an extruded form. At this time, when the aeration rotor 101 which is an aeration device is in operation, the sludge in the OD is agitated, and the sludge flows into the settling tank 103. In the sedimentation tank 103, after a certain sludge settling time, the settled sludge is extracted as return sludge or excess sludge. For this reason, sludge withdrawal schedule is determined in a manner that takes into account the operating schedule of the aeration equipment. Therefore, both the operation of the aeration device and the operation of the sludge extraction device are often set by a predetermined timer or the like.

However, the operation based on such a setting schedule has the following drawbacks.
1. Since the operation of the aeration equipment cannot guarantee the linkage with the inflow load, the treated water quality tends to be unstable.
2. Since the extraction of excess sludge does not interlock with the inflow of sewage, the excess sludge concentration tends to become unstable, which is undesirable in terms of operation management.

  Further, in the intermittent aeration by the sewage treatment apparatus according to the present invention, since the aeration time is automatically adjusted by the inflow load to perform aeration corresponding to the load fluctuation, the aeration start time and the aeration stop time are not set. It is definite. Therefore, the inflow time of sludge into the sedimentation tank after the OD is irregular, and sludge extraction with a conventional timer makes the sludge interface unstable and causes problems in maintenance such as a large variation in the drawn sludge concentration.

  In order to cope with this, in the present invention, the sludge extraction (return sludge / surplus sludge) from the sedimentation tank is controlled by receiving ON / OFF signals such as pumps for supplying inflow water and ON / OFF signals for aeration equipment. The operation command is automatically issued from the section to the sludge extraction device. FIG. 5 shows a flowchart of the surplus extraction process in such a configuration, and FIG. 6 shows a flowchart of the return sludge extraction process. Each will be described below.

Pull out excess sludge as follows.
1. Preparation for extracting excess sludge starts at a certain time. At this stage, the excess sludge is not drawn out, and the state of waiting for sludge inflow and settling into the settling tank is awaited. The fixed time generally refers to a point in time when the sludge is extracted from the subsequent sludge concentrating tank, and thus a signal indicating completion of operation of the concentrated sludge extraction pump is used, but can be freely set by the administrator.
2. At the same time as the sewage is supplied to the reaction tank (sewage pump ON signal or flow meter signal), the aeration apparatus is operated (ON signal). At this stage, sludge is pushed out of the reaction tank, and the sludge is supplied to the precipitation tank.
3. In order to ensure the amount of sludge withdrawn from the settling tank, it is necessary to ensure the stirring (aeration) time in the reaction tank until withdrawal. If the determination is NO, the process waits as it is. If YES, turn the sedimentation timer on. The settling timer is a time for waiting for the sludge flowing into the settling tank to settle in the settling tank, and can be freely set by the administrator.
4). When the settling timer expires, an operation command such as an excess sludge extraction pump is issued, and excess sludge is extracted. At the same time, set the excess sludge extraction timer to ON. Since the extracted sludge always passes through the process of settling in the settling tank, even if aeration is performed at any timing, unlike the regular extraction by the ON / OFF timer setting, the stable final settling sludge interface and the settling sludge Sludge extraction can be performed at a concentration.
5. The drawing amount is determined by the set drawing time. When the withdrawal timer is up, issue a stop command for the excess sludge pump.

The return sludge is extracted as follows.
1. Check whether excess sludge is being drawn or whether the sludge is sinking in the sedimentation tank to extract excess sludge. If so, stop returning sludge.
2. When the aeration equipment is operating (ON signal) and within a certain period after the aeration is stopped, the sludge return equipment is operated (set by a timer). Sludge is supplied to the subsequent sedimentation tank within a certain time after the aeration equipment is stopped. In order to return the sludge to the reaction tank for the purpose of stabilizing the sludge interface, it is necessary to continuously return the sludge for a certain period of time after stopping aeration.

In the pattern control period and intermittent OR automatic control period of the aeration equipment, the organic matter (CODcr) concentration and total nitrogen (TN) concentration of treated water, and the electricity consumption rate per unit treated water amount are as shown in FIG. Summarizing the results, the following conclusions can be obtained.
1. Stabilization of water quality. During the experimental period, the treated water organic matter (CODcr) concentration and total nitrogen (TN) concentration are stable.
2. Reduction of power consumption. Compared with the pattern operation of aeration equipment, the electricity consumption rate per unit treated water volume was reduced by about 15% while obtaining the same good water quality.
3. Stabilization of final sludge interface and excess sludge concentration. Since the sludge interface during the experiment period has little fluctuation and the excess sludge concentration is stable, sludge management is very easy.

The best mode for carrying out the present invention includes an oxygen requirement calculation unit and an aeration control unit, and sends air to the reaction tank based on the integrated value of the oxygen requirement, and the sewage and activated sludge flowing into the reaction tank As a result of aeration, the sludge in the sewage was removed biochemically using activated sludge, and part of the sludge that had settled in the sedimentation tank was returned to the reaction tank and the rest was discharged as excess sludge. sewage treatment apparatus odor Te, the oxygen demand calculation unit is flowing oxygen demand (or - _inflow) a calculation unit, endogenous oxygen demand - and (or _endogenous) computing unit, the supply amount of oxygen (os) computing unit And a total oxygen requirement (or) calculation unit, and the _inflowing oxygen requirement (or _-inflow ) calculation unit measures the SS (or turbidity or transparency) of the influent water with a sensor and measures it in advance. Inflow SS (or turbidity or transparency) measurements and inflow B The inflow BOD concentration and the Kjeldahl nitrogen concentration are calculated using the correlation between D and Kjeldahl nitrogen, and the calculated inflow BOD concentration and Kjeldahl nitrogen concentration and the treated water amount measured by the inflow water meter or the discharge water meter (or The required amount of inflowing oxygen is calculated from the product of the amount of inflow calculated based on the operating time of the inflow pump, etc., and the required amount of endogenous oxygen (or- _endogenous ) is calculated by measuring the MLSS with a sensor. The oxygen requirement for endogenous breathing is calculated, and the oxygen supply (os) calculation unit calculates the amount of oxygen supplied by aeration, and calculates the total oxygen requirement (or) The unit calculates a numerical value obtained by subtracting the supplied oxygen amount from the sum of the inflowing oxygen required amount and the endogenous oxygen required amount, and integrates them at regular time intervals. The operation of the aeration equipment is controlled based on the integrated value OR by the total oxygen requirement calculation unit. When the integrated value OR exceeds the aeration start set value, aeration is started and falls below the aeration stop set value. It is a sewage treatment device that automatically controls intermittent aeration by stopping aeration at a time, and further supplies inflow sewage to the reaction tank after drawing sludge from the subsequent sludge concentration tank. When the equipment starts operation, the settling timer is set to ON in advance, and excess sludge is drawn at the extraction time set when the settling timer is up, while the settling timer for extracting excess sludge is turned on. Then, except for the completion of extraction, the sewage treatment apparatus is configured to extract the returned sludge when the aeration equipment is operating and at a fixed time after the aeration is stopped .

Examples which are specific configuration examples of the present invention will be described below.
FIG. 8 is a diagram illustrating the configuration of the first embodiment of the present invention.

In the figure, reference numeral 1 denotes a reaction tank of an endless circulation channel, which causes a water flow by the aeration rotor 2 and circulates and stirs air-containing sewage and activated sludge. Further, the aeration rotor 2 operates based on a command from a control unit of the automatic controller described later . Reference numeral 3 denotes a flow path of sewage to the reaction tank 1. Reference numeral 4 denotes a flow meter for measuring the amount of inflow water provided in the sewage flow passage 3, and a signal of the measurement data is sent to a calculation unit of an automatic control device described later. In the present embodiment, the flow meter is provided in the sewage flow path, but may be provided in the flow path of the treated water to be discharged.

  Reference numeral 5 denotes a sampling device with an internal automatic cleaning function, which comprises a water tank 6, an SS meter 7 and a pH meter 8 installed therein. The sampling device 5 discharges the internal sample in a timely manner based on a command from an automatic control device to be described later, and performs cleaning by ejecting cleaning water each time. In addition, 9 is a piping for washing water, 10 is a valve, and 11 is washing water. The SS meter 7 and the pH meter 8 send measurement data signals to the calculation unit of the automatic controller described later.

  Further, the sampling device 5 is provided with a sample extraction path 12 that communicates with the sewage flow path 3 and a sample extraction path 13 that communicates with the reaction tank 1, and either of these sample extraction paths 12, 13 is selectively used. It is possible to communicate with. Reference numeral 14 denotes a passage for connecting the sample extraction passages 12 and 13 to the water tank 6 of the sampling device 5, and a pump 15 is provided in the middle. The sample extraction channels 12 and 13 are also provided with valves 16 and 17 in the middle. These pumps 15 and valves 16 and 17 operate based on commands from the control unit of the automatic control device described later. A sampling discharge passage 18 connects the water tank 6 of the sampling device 5 and the reaction tank 1. Reference numeral 19 denotes a thermometer that measures the temperature of the treated water in the reaction tank 1 and sends a signal of measurement data to a calculation unit of an automatic control device described later.

  Reference numeral 20 is a precipitation tank, 21 is a passage connecting the reaction tank 1 and the precipitation tank 20, and 22 is a passage through which the supernatant water of the precipitation tank 20 is discharged. 23 is a sludge return path connecting the bottom of the sedimentation tank 20 and the reaction tank 1, and 24 is an excess sludge extraction path connected to a middle part of the sludge return path 23. A pump 25 is provided in the middle of the sludge return path 23 between the connecting portion of the excess sludge extraction path 24 and the reaction tank 1, and a pump 26 is also provided in the middle of the excess sludge extraction path 24. ing. And these pumps 25 and 26 operate | move based on the command from the control part of a postscript automatic control apparatus. Further, in the figure, the sludge concentration tank, the concentrated sludge extraction path and the like connected to the excess sludge extraction path 24 are omitted.

An automatic control device 27 includes a calculation unit 28 that inputs and calculates data and a control unit 29 that outputs an operation control command. The calculation unit 28 includes an inflowing oxygen requirement (or _-inflow ) calculation unit, an endogenous oxygen requirement (or- _endogenous ) calculation unit, a supply oxygen amount (os) calculation unit, and a total oxygen requirement (or). It includes an oxygen required amount calculation unit (not shown) configured with a calculation unit. The control unit 29 includes an aeration control unit that controls the operation of the aeration equipment.

In addition, the inflowing oxygen required amount (or _-inflow ) calculation unit measures the SS (or turbidity or transparency) of the inflowing water with a sensor, and measures the inflow SS (or turbidity or transparency) measurement value measured in advance. The inflow BOD concentration and Kjeldahl nitrogen concentration are calculated using the correlation between the inflow BOD and Kjeldahl nitrogen, and the calculated inflow BOD concentration and Kjeldahl nitrogen concentration and the amount of treated water measured by the inflow water meter or the discharge water meter (Or the inflow amount calculated based on the operation time of the inflow pump, etc.) is used to calculate the inflowing oxygen requirement, and the endogenous oxygen requirement (or- _endogenous ) calculation unit calculates MLSS by a sensor. Measures and calculates the oxygen requirement for endogenous breathing, and the oxygen supply (os) calculator calculates the amount of oxygen supplied by aeration In addition, the total oxygen requirement (or) calculation unit calculates a numerical value obtained by subtracting the supplied oxygen amount from the sum of the inflowing oxygen requirement and the endogenous oxygen requirement, and integrates it at regular time intervals. The aeration control unit controls the operation of the aeration equipment based on the integrated value OR by the total oxygen requirement calculating unit, and starts aeration when the integrated value OR exceeds the aeration start set value. Control is performed such that intermittent aeration is automatically performed by stopping aeration when the aeration stop setting value is exceeded.

  Thus, the processing operation according to the present embodiment is as described above, and thus detailed description thereof is omitted, and a brief description thereof is as follows.

  The inflow SS (or turbidity or transparency) and MLSS used for the calculation of the required oxygen amount are measured intermittently using the sampling device 5. As shown in FIG. 9, a real-time measurement value or a filtered value is used when measuring, but when a measurement is not performed, the value at the time of completion of the previous measurement is held and used. The required oxygen amount calculation unit in the calculation unit 28 of the automatic control device 27 calculates the required oxygen amount from the sensor value measured by the sampling device 5, the device ON / OFF signal, or the input signal from the flow meter or the like. In addition, the control unit 29 of the automatic control device 27 issues an operation / stop command to the aeration equipment based on the integrated value of the required oxygen amount as described above, and for sludge control according to the process charts shown in FIGS. Control is performed by issuing an operation / stop command or an open / close command to each device.

Next, a second embodiment of the present invention shown in FIG. 10 will be described.
The difference between the present embodiment and the first embodiment is that the sampling device with the internal automatic cleaning function in the first embodiment is not used in the present embodiment.

  Thus, in the case of the present embodiment, the inflow SS (or turbidity or transparency) and MLSS values are continuously measured by a sensor installed in the OD, and real time as shown in FIG. Measured value or filtered value is used. In addition, since other configurations and operations are the same as those of the first embodiment, the same members are denoted by the same reference numerals, and detailed description thereof is omitted.

Next, a third embodiment of the present invention shown in FIG. 12 will be described.
This embodiment relates to an agricultural settlement wastewater treatment apparatus, and shows examples of JARUS-XIV type (continuous inflow-intermittent aeration) and JARUS-XV type (intermittent inflow-intermittent aeration).

  The difference between the present embodiment and the first embodiment is that, in the reaction tank and the aeration apparatus, the first embodiment uses a reaction tank of an endless circulation channel, and aeration is performed by generating a water flow with an aeration rotor. Thus, this embodiment is not a reaction tank of an endless circulation channel, and also uses a diffused aeration method with a blower and a diffuser member, and in this embodiment, in the middle of the flow path of sewage to the reaction tank. In addition, a pump and a metering device for sending measurement data signals to the arithmetic unit of the automatic control device are provided.

  That is, the reaction tank 30 is used in place of the reaction tank 1 of the endless circulation channel in the first embodiment. In this embodiment, two reactors are arranged in parallel. In addition, the air sent out from the blower 31 is sent into the reaction tank 30 through the air blowing path 32 and discharged from the aeration member 33 at the bottom of the reaction tank 30 for aeration. Further, the air passage 32 is provided with valves 34, 34, and these valves 34, 34 and the blower 31 operate based on a command from the control unit 29 of the automatic control device 27. A pump 35 and a metering device 36 are provided in the middle of the sewage flow passage 3 to the reaction tank 30, and these pump 35 and metering device 36 send a signal of measurement data to the arithmetic unit 28 of the automatic control device 27. Is. In addition, a pump 25 is provided in the middle of the sludge return path 23 between the connecting portion of the excess sludge extraction path 24 and the settling tank 20, and the excess sludge extraction path 24 and the excess sludge extraction path 24 in the sludge return path 23 are provided. Valves 37 and 38 are provided in the middle of the connection portion closer to the reaction tank 30, respectively. The pump 25 and valves 37 and 38 are operated based on commands from the control unit 29 of the automatic control device 27.

  Thus, in the case of this embodiment, the method for measuring the inflow SS (or turbidity or transparency) and MLSS is the same as in the first embodiment, and the inflow amount F is the same as that of the inflow sewage pump 35. It is determined from the flow rate per time determined by adjusting the ON / OFF signal and the measuring device triangular weir 36 and the like. In addition, since other configurations and operations are the same as those of the first embodiment, the same members are denoted by the same reference numerals, and detailed description thereof is omitted.

It is explanatory drawing of the basic composition of this invention. It is a graph which shows the performance curve of the oxygen supply capability of an aeration apparatus. It is explanatory drawing of the aeration control which controls the operation | movement of an aeration apparatus based on the time-dependent change of inflowing oxygen required amount, and the integrated value of load. It is composition explanatory drawing of the sewage treatment apparatus by the oxidation ditch method which has sludge concentration equipment. It is a flowchart of the excess sludge extraction process by this invention. It is a flowchart of the return sludge extraction process by this invention. It is a graph which shows the comparative measurement of the organic matter (CODcr) density | concentration and total nitrogen (TN) density | concentration of the treated water in the pattern control of the conventional aeration apparatus, and the intermittent OR automatic control apparatus by this invention, and the electric consumption rate per unit treated water quantity. is there. BRIEF DESCRIPTION OF THE DRAWINGS It is structure explanatory drawing of Example 1 of this invention. It is a graph which shows the time-dependent change of inflow SS at the time of using a sampling device. It is composition explanatory drawing of Example 2 of this invention. It is a graph which shows the time-dependent change of inflow SS when not using a sampling device. It is composition explanatory drawing of Example 3 of this invention.

DESCRIPTION OF SYMBOLS 1 Reaction tank 2 Aeration rotor 3 Flow path of sewage 4 Flowmeter 5 Sampling device 6 Water tank 7 SS meter 8 pH meter 12, 13 Sample extraction path 14 Path 15 Pump 16, 17 Valve 18 Sample extraction path 19 Thermometer 20 Precipitation tank 23 Sludge return path 24 Excess sludge extraction path 25, 26 Pump 27 Automatic control device 28 Arithmetic unit 29 Control unit 30 Reaction tank 31 Blower 32 Blower channel 33 Air diffuser member 34 Valve 35 Pump 36 Metering device

Claims (2)

It is equipped with an oxygen requirement calculation unit and an aeration control unit, sends air to the reaction tank based on the integrated value of the oxygen requirement, aerates the sewage and activated sludge flowing into the reaction tank, and activates sludge in the sewage while biochemically removed by the precipitated sludge in the settling tank, a portion is returned to the reaction vessel, the rest Te sewage treatment apparatus odor when taken to discharge the excess sludge, the oxygen required amount calculating section The inflowing oxygen requirement (or _-inflow ) calculation unit, the endogenous oxygen requirement (or- _endogenous ) calculation unit, the supply oxygen amount (os) calculation unit, and the total oxygen requirement (or) calculation unit The _inflowing oxygen requirement (or _-inflow ) calculating unit is configured to measure the SS (or turbidity or transparency) of the inflowing water with a sensor, and to measure the inflow SS (or turbidity or transparency) measured in advance. The correlation between inflow BOD and Kjeldahl nitrogen To calculate the inflow BOD concentration and Kjeldahl nitrogen concentration, and the calculated inflow BOD concentration and Kjeldahl nitrogen concentration and the amount of treated water measured by the inflow water meter or the discharge water meter (or the operation time of the inflow pump, etc.) The inflowing oxygen requirement is calculated from the product of the inflowing oxygen), and the endogenous oxygen requirement (or- _endogenous ) calculation unit measures MLSS with a sensor, and the oxygen requirement for endogenous respiration. The supply oxygen amount (os) calculation unit calculates the amount of oxygen supplied by aeration, and the total oxygen requirement (or) calculation unit calculates the inflowing oxygen requirement amount. A numerical value obtained by subtracting the amount of supplied oxygen from the total amount of endogenous oxygen required is calculated and integrated at regular time intervals, and the aeration control unit is an integrated value O obtained by the total oxygen required amount calculating unit. Based on the above, the operation of the aeration equipment is controlled, and when the integrated value OR exceeds the aeration start set value, aeration is started, and when it falls below the aeration stop set value, aeration is automatically stopped. It is a sewage treatment device that is controlled to perform intermittent aeration, and after the sludge is extracted from the subsequent sludge concentration tank, the inflow sewage is supplied to the reaction tank, and optionally when the aeration equipment starts operation. The settling timer is set to ON, and the excess sludge is drawn with the extraction time set when the settling timer has timed up. A sewage treatment device that draws back the returned sludge when the equipment is in operation and after a certain period of time after stopping aeration. A processing device that can control the amount of aeration air or the number of rotations of the aeration equipment, and adjusting the amount of aeration air or the number of rotations when the daily aeration time exceeds the aeration time upper limit and when the aeration time lower limit is exceeded. The sewage treatment apparatus according to claim 1, further comprising an aeration control unit capable of automatically adjusting the aeration air volume or the rotation speed so that the aeration time is controlled within an appropriate range.

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