KR101046534B1 - Automatic Control Method of Inflow Flow Control Membrane Activated Sludge Process - Google Patents

Abstract

The present invention provides an automatic control method and apparatus for an inflow flow control membrane separation activated sludge process.

The present invention, in the inflow flow control type membrane separation method in which the influent and sludge transfer is changed in a time period, detecting the complete denitrification time by measuring the ORP change over time in real time in the reactor in which anoxic and anaerobic processes are alternately performed according to the inflow flow The inflow flow control time is then automatically controlled to ensure sufficient time for phosphorus release. Thus, by securing the time required for the actual phosphorus release, it is possible to increase the efficiency of phosphorus release compared to the process of operating by fixing the existing anaerobic tank for 1-2 hours, and ultimately the treatment efficiency of nitrogen, phosphorus can be increased. In addition, compared to the recent trend of using the COD or N, P ion concentration meter for automatic control of the advanced processing process, by using the ORP meter, which is a general-purpose measuring instrument, the automatic control process can be constructed at a low price. In addition, maintenance costs can be minimized through process automation.

Immersion type, membrane, flow path change, sewage treatment, automatic control, ORP meter

Description

Method of Automatic Control of Inflow-flow Controlled Membrane Activated Sludge Process {AN AUTO-CONTROL METHOD OF WASTEWATER TREATMENT BY INFLUENT CONTROLLED MEMBRANE BIOREACTOR}

The present invention relates to an automatic control method and apparatus for an inflow flow control membrane separation sludge process for simultaneous treatment of nitrogen and phosphorus, and in detail, is arranged in parallel and two anaerobic and anaerobic tanks are operated according to the flow of influent and sludge. It is an automatic control method of sewage water treatment method that removes organic matter, nitrogen and phosphorus from sewage water simultaneously by using membrane separation activated sludge device composed of semi-anaerobic tank and membrane filtration tank immersed in microfiltration membrane. It detects the end of denitrification and observes the formation of complete anaerobic conditions, and controls the inflow flow control cycle in real time to ensure the minimum time required for phosphorus release.

Biological nitrogen and phosphorus treatment processes can be classified in several ways, depending on the composition and operation of the reactor: A / O (Anaerobic / Oxic), A2 / O (anaerobic / anoxic / oxic), UCT (University of Capetown) For example, it is classified into a main stream process in which anaerobic, anaerobic, and aerobic tanks are connected in series, such as Bardenpho, and a side stream process in which anaerobic dephosphors are connected in parallel, such as Phostrip and PL-II. In addition, it can be classified into a spaced batch type in which the phase of the reactor is fixed and a timed batch process in which the phase of the reactor changes with time. Although the various processes described above are relatively excellent in processing efficiency, although the problems such as sludge swelling, microfloc and sludge injuries often occur in subsequent gravity settling tanks due to changes in temperature and operating conditions, the biotreatment process has been optimized. The problem is that the quality of the treated water is worsened. In addition, the gravity sedimentation method used in the above-described conventional process is difficult to maintain the concentration of microorganisms in the reaction tank at a predetermined level or more, so that the ability to cope with high loads is poor, there is a limit to maintain a relatively long hydraulic residence time. Membrane Bio is a membrane-combined biotreatment method that combines biological filtration process and membrane filtration method to achieve solid-liquid separation stably using separation membrane with constant nominal pore instead of solid-liquid separation by gravity sedimentation. -Reactor, or MBR.

However, the MBR method for advanced treatment, which has been developed at home and abroad until now, is a combination of A2O-based bioreactors and membranes, such as "biological nitrogen, phosphorus removal apparatus and method using immersion membranes" (Korean Patent Publication No. 2002-44820). Most of them take up a large amount of nutrients compared to nitrogen and phosphorus. However, if A2O-like method is applied to domestic wastewater with lower concentration of nutrient sources, denitrification efficiency is reduced due to lack of carbon source. As a result, nitrate nitrogen is introduced into the anaerobic tank through the return sludge. The organic competition between Poly-P bacteria and denitrification microorganisms occurs, which leads to low phosphorus emission.

In order to solve the problems of the prior arts, the inventors alternately introduce raw water and return sludge into two semi-anaerobic reactors at time periods to alternately induce anoxic conditions and anaerobic conditions, followed by an aerobic separation membrane tank. It has been proposed that the "sewage water treatment method using the inflow flow control membrane separation activated sludge method" characterized in that the nitrification and solid-liquid separation by installation (Korea Patent No. 0555689).

Figure 1 shows the process flow diagram of the "wastewater treatment method using the inflow flow control membrane separation activated sludge method" to which the present invention is applied. In Fig. 1, the flow path changing device 2 alternately supplies anoxic and anaerobic conditions to the two reactors by supplying the incoming wastewater 1 to the reactors A 3 and B 4 at regular intervals. It serves to maintain. In addition, the sludge solubilization tank 11 is connected to the solubilized sludge through the flow channel changer 2 to the bioreactor to reduce the sludge by re-decomposing the carbon source.

In more detail, in the present invention, the reaction tank A (3) is supplied with raw water and sludge returned from an aerobic separation membrane tank to perform biological denitrification under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) is operated in a batchwise state in the state of the external inflow is cut off (S1); and the reaction tank B (4) is supplied with sludge returned from the raw water and aerobic separation membrane tank organic matter contained in the raw water Using a carbon source as a carbon source to perform biological denitrification under anoxic conditions, and reactor A (3) is operated batchwise with the external inlet cut off, so that step (S2) in which phosphorus is released alternately is operated. It features. At this time, the inflow of sewage water and return sludge is blocked, and thus the reactor operated in a batchwise manner has no supply of nitrate nitrogen, so it is possible to maintain an anaerobic condition and to release phosphorus more efficiently.

In addition, the treated water passing through the reaction tank maintained in the anoxic conditions in the step S1 or S2 is introduced into the aerobic separation tank (5) of the rear stage, the introduced treated water is highly concentrated sludge (8) through the immersion membrane (6) Is discharged as the final purified water (7).

In the present invention, the operating cycle of the flow path changing device 2 for adjusting the steps S1 and S2 is normally controlled by a timer by selecting an appropriate value in the range of 1 to 3 hours.

However, since the end point of denitrification may vary depending on the conditions of the influent wastewater and the operation conditions of the reactor, there is a problem that it is difficult to secure sufficient time required for phosphorus release when the operation cycle of the flow path changing device is determined to a predetermined value.

On the other hand, the method of detecting the end point of nitrification and denitrification by using pH or ORP (Oxidation Reduction Potential) inflection point alone or in combination and controlling the aeration-non-aeration time in real time is widely used in sewage treatment method including SBR or intermittent aeration process. It is utilized. In the case of Korean Patent No. 0338510, anitrogen break point (NBP) whose pH suddenly increases by the end of nitrification is detected by using the change amount of pH value over time, and aeration is stopped, and denitrification process is started. In the process, it detects NKP (Nitrate Knee Point) which suddenly decreases ORP value and stops anoxic treatment as the completion point of denitrification, so that nitrification and denitrification are induced smoothly by controlling the blower. However, the target method of the patent is to detect the point of denitrification by the aerobic treatment method, continuous batch method (SBR) or intermittent aeration method is for the conversion to an precipitation step in anoxic conditions, separately if phosphorus removal is required It is maintained for 2-4 hours after wastewater inflow. In other words, the anaerobic tank in the control method of the patent secures only physical time regardless of whether or not a complete anaerobic condition is formed, and is not aware of securing an effective anaerobic duration.

In addition, the Korean Patent No. 0628908 adopts a method of controlling the operation of the internal conveying pump through a calculation that compares the absolute value of ORP in the anaerobic / anaerobic shift reactor with a preset ORP value.

However, these conventional measurement methods are configured to set a reference value for the ORP value or the ORP temporal change value (dORP / dt), and to determine the reaction stage in comparison with the above, and to respond in real time to changes in the inflow load or changes in the reactor operating conditions. Since it is difficult to do so, the effectiveness of the reference value is questioned.

In particular, it is not suitable for the method of maximizing phosphorus emission by forming absolute anaerobic conditions in the batch operation stage by changing the flow path such as the "inflow flow control membrane separation activated sludge process", and is a measurement for automatic operation of the process in real time. No method or automatic control system has been developed.

Most of the organic and nitrogen and phosphorus simultaneous treatment methods developed at home and abroad are operated by fixing the anaerobic tank residence time to 1-2 hours, but in reality, it is difficult to form a complete anaerobic condition due to the nitrate nitrogen contained in the internal transport sludge. As a result, phosphorus release was poor. In the present invention, by providing a measurement control method and apparatus suitable for the "inflow flow control membrane separation activated sludge process" to automatically control the flow change time in real time to ensure sufficient time required for phosphorus discharge after the denitrification is completed, sewage altitude In order to improve the treatment efficiency of pollutants in the treatment process.

The present invention is to observe the formation of the complete anaerobic conditions through the time change value of the ORP of the reactor operated in a batch, as well as to automatically release the phosphorus discharge by real-time automatic control of the flow channel change to ensure sufficient time required for phosphorus discharge To provide automatic control method and automatic control system of inflow flow control membrane separation activated sludge process to maximize and finally improve the treated water quality.

The present invention relates to a method for automatically controlling the operation cycle of a flow path changer in real time in the "Waste water treatment method using an inflow flow control membrane separation activated sludge process", and more particularly, a reactor operated in a batch state in which an external inflow is cut off. ORP is measured in real time and the time change (dORP / dt) of ORP is calculated to detect NKP (Nitrate Knee Point), which indicates the point at which denitrification is terminated, and when NKP is detected. It is a technology that automatically controls the flow path changing device to operate after a certain time required for the discharge of phosphorus, which is an effective anaerobic duration time. NKP, which occurs during the denitrification process, means that all of the nitrate nitrogen is completely depleted at the end of the denitrification process. If there is an organic substrate (carbon source) in the reactor, the reactor enters a complete anaerobic state, not anoxic state. Done.

The first aspect of the present invention relates to a real-time automatic control method of the inflow flow-controlled membrane separation activated sludge method, in detail, the flow path changing device (2), reactor A (3), reactor B (4), membrane separation tank ( 5); Reactor A (3) receives the sludge conveyed from the raw water and the membrane tank (5) through the flow path changer (2) to perform biological denitrification reaction under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) receives the sludge conveyed from the raw water and the separation membrane tank (5) by the step (S1) and the reaction tank B (4) is operated batchwise in the state that the external inflow is cut off through the flow path changing device (2) Conducting biological denitrification under anoxic conditions using organic matter contained in raw water as a carbon source, and reaction tank A (3) is operated in a batchwise manner (S2) in which the inflow is cut off; Immersion type separation membrane (6) is installed in the membrane separation tank (5) to concentrate the sludge and discharge the treated water at the same time, the highly concentrated sludge is to be circulated internally to the reaction tank in an oxygen-free condition through the flow path changing device (2) As an automatic control method of an inflow-controlled membrane separation activated sludge method which simultaneously removes nitrogen and phosphorus by repeatedly performing anoxic and anaerobic conditions, the deoxidation is measured by measuring the redox potential change (dORP / dt) of the batch reactor. After detecting NKP (Nitrate Knee Point), which is the oxidation end point, phosphorus is released for a certain time, and then the flow path of the flow path changing device 2 is changed so that the batch operation time (T) elapses until the NKP is detected after disconnecting the inflow. (t ₁₎ and the set is automatically controlled by the sum of the discharge time (t _e), at the same time, the operating time of the character anaerobic denitrification reactor in the same way and the batch operating time (t) Characterized in that the control.

The second aspect of the present invention relates to a periodic automatic control method of the inflow flow control membrane separation activated sludge process, characterized in that it comprises the following steps.

a) setting the step S1 operation time (T _a ) and the step S2 operation time (T _b ) to the same (T _a = T _b = T);

b) detecting the NKP at the end of denitrification by measuring the ORP of the reactor operated batchwise in the step S1 or S2;

c) measuring an elapsed time (t ₂ = Tt ₁ ) from the NKP detection (t ₁ ) to the operation time (T);

d) comparing the elapsed time (t ₂ ) with a phosphorus release time (t _e ) which is previously determined and obtained by measuring; And

e) the elapsed time (t ₂₎ the operating time in this case is shorter than the the release time (t _e) such that longer than the elapsed time (t ₂₎ is the the release time (t _e) the step S1 and the step S2 ( T) resetting.

The third aspect of the present invention relates to an automatic control system of an inflow flow control membrane separation activated sludge process, and to detect the denitrification time of a reactor operated in a batch of step S1 or step S2, any of reactor A or reactor B. ORP sensor installed at one or more to measure the redox potential inside the reactor, timer for opening and closing control of the flow path changer, denitrification time point (NKP) from the value (dORP / dt) input from the ORP sensor through an analog / digital converter And a processor for controlling the open / close control timer from the denitrification time and the effective anaerobic time required for phosphorus release, and an analog signal input from the ORP sensor and the open / close control timer as a digital signal. Input to the computer and output from the computer An analog / digital converter (A / D converter) for converting the digital signal into an analog signal and outputting.

The membrane separation activated sludge method further includes a sludge solubilization tank 11 at the rear end of the membrane separation tank 5 so that a part of the highly concentrated sludge is solubilized in the sludge solubilization tank 11 and then the flow path changing device 2 Through it can be introduced into the reactor in anoxic conditions can be used as a carbon source.

The NKP is detected at a point where the redox potential change (dORP / dt) value of the batch reactor is minimum, and is detected in a range where the redox potential change (dORP / dt) value is -2 to -20 mV / min.

The phosphorus release time (t _e ) is preferably adjusted in advance to 1 hour or more, more specifically 1 hour to 3 hours. In addition, by installing a PO ₄ -P continuous measuring device installed in any one or more of reactor A or reactor B to measure the concentration of phosphorus in the reactor, phosphorus release after detection of NKP is 7 mg / L to 12 mg is a typical target release amount You can adjust the batch duration until / L is reached.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, lengths, thicknesses, and the like of layers and regions may be exaggerated for convenience. Like numbers refer to like elements throughout.

Figure 2 is a schematic diagram of an automatic control system of the inflow flow control membrane separation activated sludge method for controlling the change cycle of the flow path through the ORP measurement according to the present invention. The advanced sewage water treatment MBR method (1-12) characterized by the inflow flow control includes a flow path changing device (2), reactor A (3), reactor B (4), and membrane separation tank (5); Reactor A (3) receives the sludge conveyed from the raw water and the membrane tank (5) through the flow path changer (2) to perform biological denitrification reaction under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) receives the sludge conveyed from the raw water and the separation membrane tank (5) by the step (S1) and the reaction tank B (4) is operated batchwise in the state that the external inflow is cut off through the flow path changing device (2) Conducting biological denitrification under anoxic conditions using organic matter contained in raw water as a carbon source, and reaction tank A (3) is operated in a batchwise manner (S2) in which the inflow is cut off; Immersion type separation membrane (6) is installed in the membrane separation tank (5) to concentrate the sludge and discharge the treated water at the same time, the highly concentrated sludge is to be internally circulated to the reaction tank in an oxygen-free condition through the flow path changing device (2). .

An automatic control system of an inflow-flow controlled membrane separation activated sludge process for simultaneously removing nitrogen and phosphorus, the automatic control system according to the present invention for detecting the denitrification time of the reaction tank operated in a batch of step S1 or step S2. ORP sensors 21 and 22 installed in at least one of Reactor A or Reactor B to measure the redox potential (ORP) inside the reactor; An open / close control timer 25 of the flow path changing device; The denitrification time (NKP) is determined from the value (dORP / dt) input from the ORP sensor through the analog / digital converter, and the open / close control timer 25 is controlled from the denitrification time and the effective anaerobic time required for phosphorus release. A digital input / output computer 24 including a processor for performing the processing; And converts analog signals input from the ORP sensors 21 and 22 and the open / close control timer 25 into digital signals, inputs them to the computer 24, and converts digital signals output from the computer into analog signals. An analog / digital converter (A / D converter) 23 is included. In addition, the automatic control system according to the present invention is installed in any one or more of the reaction vessel A or reactor B to determine the phosphorus release time of the reactor operated in the batch of step S1 or S2 phosphorus to measure the phosphorus concentration inside the reactor A concentration measuring device may be further provided.

In FIG. 2, the flow channel changer 2 alternates anoxic and anaerobic conditions to the two reactors by supplying the incoming wastewater 1 to the reactors A 3 and B 4 at regular intervals. It serves to keep. In more detail, Reactor A (3) is supplied with sludge conveyed from raw water and a membrane tank and solubilized solubilized in the sludge solubilization tank to perform biological denitrification by using organic matter and solubilized sludge as carbon sources. In addition, reactor B (4) is operated batchwise in the state in which the external inflow is disconnected to completely denitrate the remaining nitrogen nitrate, and then anaerobic conditions to perform the function of the anaerobic tank to release the phosphorus.

After a certain time elapses, the flow path is changed to flow into the reactor B (4) from the flow path changing device (2), wherein the reaction tank A and the reaction tank B performs the function opposite to the previous flow. At this time, the inflow control cycle has been empirically calculated through pilot operation in the range of 1-3 hours.

According to the present invention, ORP meters are installed in Reactor A and Reactor B in which anaerobic and anaerobic conditions are alternately performed according to the inflow conditions, and are measured in real time, and the ORP change during the unit time at the stage of inflow is stopped (dORP / dt) is calculated to detect NKP, the end point of denitrification, and is configured to change the flow path in the inflow flow changer 2 after sufficient time for phosphorus release is secured.

In more detail, as shown in FIG. 2, an ORP meter is installed in either or both reactors A and B or in one of the reactors, and the ORP measurement time interval is 10 seconds to 5 minutes, and more preferably 30 seconds to It can be in the range of 3 minutes intervals. If the measurement interval is outside the above range, the amount of data may be too large to be detrimental to the system operation or may not represent the reactor state as a real time value. If necessary, the change in the moving average value may be measured 3 to 10 times. For example, if the ORP change value is calculated at 1 minute intervals, a graph as shown in FIG. 4 can be obtained. In the inflow stage, 100-300% of the return sludge is introduced from the membrane separation tank together with the inflow water, and since the ORP value of the returned sludge is usually +100 to + 600mV, the reaction tank is used during the inflow time. The ORP value of A or Reactor B represents a rising pattern. On the other hand, while the inflow is stopped, since the ORP decreases rapidly when the remaining nitrogen nitrate (NO ₃ -N) is completely depleted, the dORP / dt value shows the minimum value. In a preferred embodiment of the invention the dORP / dt minimum is detected in the range of -2 to -20 mV / min. After the NKP with the smallest dORP / dt value is detected, the flow path changing device 2 is started after the set time required for the phosphorus discharge, and the inflow is started in the reactor A or the reactor B operated in a batchwise manner. After NKP, the elapsed time to be secured under the actual anaerobic condition depends on the inflow water and the target water quality, but is usually 1 hour or more, more specifically, 1 hour to 3 hours. Referring to Figure 3, through the phosphorus concentration measuring devices (31, 32) provided in the reactor A and reactor B after measuring the concentration of phosphorus (PO ₄ -P) after NKP anaerobic until the value set to the target emission value Condition can be maintained. At this time, the target emission amount is in the range of 7mg / L to 12mg / L.

5A illustrates an example of a method of controlling the flow path change period in real time by the ORP change value in the automatic control method according to the present invention.

Referring to FIG. 5A, when the first flow channel change valve is operated to proceed to step S1, the reactor A is denitrified under anoxic conditions as raw water and organics are introduced, and at the same time, the reactor B is stopped so that the reaction is performed in a batchwise manner. do. At this time, the reaction time of the step S1 is measured in real time ORP change in the reaction tank B consisting of a batch to detect the denitrification time point (NKP) when the ORP change value is the minimum and after the elapsed time (t _b 1) until NKP detection The process is continued for an effective anaerobic time, ie phosphorus release time (t _e ). Therefore, the reaction time of the step S1 is equal to the inlet stop time of reactor B and the same as the inlet time (T _a ) of reactor A, T _a is controlled by the sum of t _b 1 and t _e . Subsequently, in the step S2, the flow path is changed by the operation of the flow path changing device to make the inflow to the reaction tank B, and the inflow to the reaction tank A is stopped. Determination of the denitrification time (NKP) at the time when the ORP change value is the minimum and the effective anaerobic time after the elapsed time (t _a 1) until the detection of NKP is detected. The process is continued for time t _e . Therefore, the reaction time of the step S2 is equal to the inlet stop time of reactor A and the same as the inlet time (T _b ) of reactor B, T _b is controlled by the sum of t _a 1 and t _e .

The phosphorus release time (t _e ) may be set to 1 to 3 hours in advance, and when the phosphorus concentration measuring device is provided in the inlet stopping reaction tank, that is, the batch reaction tank, the phosphorus concentration is measured up to a predetermined target release amount. You can set the time to reach.

Since the elapsed time (t _b 1, t _a 1) until the detection of NKP may vary according to the change of influent material in the reaction vessel, phosphorus release after the elapsed time (t _a 1) until the detection of NKP is substantially realized. By ensuring the time that is made surely, the removal efficiency of phosphorus (P) in the sewage can be significantly improved, and when the phosphorus concentration measured by the phosphorus concentration measuring device is set, the phosphorus removal time can be further improved. .

Considering the convenience of operating the system and setting the conditions of Reactor A and Reactor B to be the same, there is almost no substantial difference even assuming that the reaction times of Steps S1 and S2 are the same. Therefore, by setting the reaction time of steps S1 and S2 equally (T = T _a = T _b ), the reaction time can be controlled by measuring only the ORP of either reactor A or reactor B. The control method in the case where the reaction time of steps S1 and S2 is set to be the same (T = T _a = T _b ) is illustrated in FIG. 5B.

In addition, in addition to the method of controlling the flow path change period in real time based on the ORP change value, a period is calculated by operating at a predetermined period for a specific time, and the flow path change period is changed again when the calculated period is markedly different from the current operation cycle. In addition, such a periodic automatic control method includes the following steps.

a) setting the step S1 operation time (T _a ) and the step S2 operation time (T _b ) equally (T _a = T _b = T);

b) detecting the NKP at the end of denitrification by measuring the ORP of the reactor operated batchwise in the step S1 or S2;

c) measuring an elapsed time (t ₂ = Tt ₁ ) from the NKP detection (t ₁ ) to the operation time (T);

d) comparing the elapsed time (t ₂ ) with the phosphorus release time (t _e ) obtained by setting or measuring in advance; And

e) the elapsed time (t ₂₎ the operating time in this case is shorter than the the release time (t _e) such that longer than the elapsed time (t ₂₎ is the the release time (t _e) the step S1 and the step S2 ( T) resetting.

An example of the periodic automatic control method as described above is illustrated in FIG. 6. Referring to FIG. 6, the reaction time of the step S1 and the reaction time of the step S2 are set to be the same, and the cycle calculation period for the flow path change period is set to 1 day (1440 minutes), and the flow path change period (S1 step reaction) is predetermined. Monitor the ORP change in Reactor A while running for 1 day with time = S2 step reaction time = T). The process time at which step S1 (T) in which reactor A is operated under anoxic conditions and step S2 (T) in which reactor A is operated batchwise is the sum of the operating times of each step (2T). When the process period 2T is performed for one day, the set operating time T is greater than the sum of the elapsed time ta1 until detection of NKP measured in real time and the phosphorus emission time Te obtained by setting or measuring in advance. If large, it is regarded as a normal process and a normal process number n is calculated. The phosphorus release time may be set to a time value in advance as described above, or may be determined from a phosphorus concentration measurement value through a phosphorus concentration measuring device. After the operation is completed for one day, if the normal number of processes (n) is 50% or more of the number of processes (m), the operation period (T) is not changed, and if it is less than 50%, the operation is added by 30 minutes. Reset cycle (T = T + 30) to allow next day operation. Whether or not to reset the operation cycle when the number of normal processes in the calculation period or the process performed for one day is less than%, and how much time to add during the reset may be changed in consideration of process conditions, influent wastewater conditions, and the like. .

Most of the simultaneous treatment of organic matter, nitrogen and phosphorus treatment for sewage water treatment is designed for the proper residence time of denitrification and nitrification tanks for nitrogen removal or automatic control technology in actual process operation. The residence time is generally applied in a range of 1-2 hours, and in terms of functional aspects, dissolved oxygen or nitrate nitrogen remains in accordance with the sludge conveying flow, so that the actual anaerobic conditions are not achieved, resulting in low phosphorus emission. There is a problem.

In the present invention, the reactor to perform the anaerobic and anaerobic conditions alternately according to the flow path to monitor the progress of the denitrification reaction through real-time ORP measurement, to ensure the actual time required for phosphorus release after the actual complete anaerobic conditions are established By automating the process, it is possible to maximize phosphorus release and ultimately increase nitrogen removal efficiency as well as nitrogen. In addition, by using the general-purpose instrument of the ORP meter as a measurement factor, it is possible to configure an automatic control process at a low price, and also to reduce maintenance costs.

The present invention will be described in more detail with reference to the following Examples. However, the following examples are merely examples of the present invention, and the claims of the present invention are not limited thereto.

Example

In accordance with the present invention, an inflow flow controlled membrane separation activated sludge process pilot of 60 m ³ / day treatment scale was operated. The HRT of each reactor was 1.5 hours for each reaction tank A and B for 3.0 hours, and the membrane separation tank 3.0 hours. The residence time of the sludge solubilization tank, which induces solubilization of excess sludge by the alkaline alkaline strain, was about 24 hours. The source of inflow was municipal sewage at D, and the separator was c-PVC material and a flat microfiltration membrane with a nominal pore size of 0.4㎛ was applied. In connection with the PC-PLC-based automatic control program applied to Figure 5b was configured to calculate the flow path change in real time and automatically configured, the operating conditions are shown in Table 1 below. 7 shows an MMI screen for process operation control in a PC-PLC based automatic control program, and FIG. 8 shows a NKP detection screen through real-time variation monitoring of ORP and ORP changes in a PC-PLC based automatic control program. .

[Table 1] Operation Conditions of Inflow Flow Control Membrane Separation Activated Sludge System

An ORP meter was installed in Reactor A, and dORP / dt was calculated at 1 minute intervals as shown in FIG. 4, and was configured to detect the minimum value through comparison with all time zones dORP / dt. In this example, the lowest ORP value of reactor A was -260 mV ± 50 mV during the batch operation period, and the lowest value of dORP / dt was detected between about -5 and -8.

9 is a graph showing the internal behavior of nitrogen and phosphorus ions in each reactor according to the automatic flow path change. During the period in which the inflow was blocked, the remaining nitrate nitrogen concentration was depleted to less than 0.5 mg / L within the initial 20 minutes, and phosphorus release occurred from this point, increasing the phosphate phosphorus concentration up to 8 mg / L in anaerobic conditions. The automatic control of the flow path change showed that the mechanism of nitrogen and phosphorus removal was effective.

The pollutant treatment efficiency obtained through this example is shown in Table 2 below.

[Table 2] Pollutant Treatment Efficiency

1 is a schematic diagram of an inflow controlled membrane separation activated sludge process for simultaneous treatment of nitrogen and phosphorus.

Figure 2 is a block diagram of the automatic control system of the inflow flow control membrane separation activated sludge method according to the present invention.

3 is a block diagram of the automatic control system of the inflow flow control membrane separation activated sludge method according to the present invention further comprising a phosphorus concentration measuring device.

Figure 4 is a graph showing the ORP value and the amount of change (dORP / dt) during the unit time in the reactor according to the flow path change of the flow control type membrane separation activated sludge method.

FIG. 5 is a flowchart for real-time control of a flow path change period through an ORP change value. FIG. 5A illustrates a case in which a reaction time of step S1 and a reaction time of step S2 are operated differently, and FIG. 5B is S1. This is the case when the step reaction time and the reaction time of step S2 are operated the same.

6 is a flowchart for examining whether the flow path change period is corrected through the ORP change value (Pre-Time Control).

7 is an MMI screen for process operation control according to an embodiment of the present invention.

8 is an NKP detection screen through real-time fluctuation monitoring of ORP and ORP change amount as an embodiment of the present invention.

9 is a graph showing a change in the concentration of nitrogen and phosphorus in the reactor according to the time period as an embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

1: Influent wastewater 2: Inflow flow changing device 3: Reactor A

4: Reactor B 5: Membrane separation tank 6: Submerged membrane

8: High concentration sludge 9: Excess sludge discharge 10: Sludge conveyed

11: Sludge Solubilization Tank 12: Solubilized Sludge Transfer Path

23: AC / DC converter 24: Computer for operation control

25: Timer 21, 22: ORP meter

31, 32: phosphorus concentration measuring device

Claims (12)

It includes a flow path changing device (2), Reactor A (3), Reactor B (4), Membrane separation tank (5), Reactor A (3) receives the sludge conveyed from the raw water and the membrane tank (5) through the flow path changer (2) to perform biological denitrification reaction under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) receives the sludge conveyed from the raw water and the separation membrane tank (5) by the step (S1) and the reaction tank B (4) is operated batchwise in the state that the external inflow is cut off through the flow path changing device (2) The organic material contained in the raw water is used as a carbon source to perform biological denitrification under anoxic conditions, and reactor A (3) is operated in a batchwise manner (S2) in which the external inflow is cut off. An immersion type separation membrane 6 is installed in the membrane separation tank 5 to concentrate the sludge and discharge the treated water at the same time. , As an automatic control method of inflow control type membrane separation activated sludge method that removes nitrogen and phosphorus simultaneously by repeatedly performing anoxic and anaerobic conditions, After measuring the redox potential change (dORP / dt) of the batch reactor, after detecting NKP (Nitrate Knee Point) which is the end point of denitrification, phosphorus is released for a predetermined time, and then the flow path of the flow path changing device 2 is changed. As a result, the batch operation time (T) is automatically controlled by the sum of the elapsed time (t ₁ ) and the phosphorus release time (t _e ) until the NKP detection after disconnection of the external inlet, and at the same time, the operation time of the anoxic denitrification reactor is also the batch operation time (T). Automatic control method of inflow flow control type membrane separation activated sludge method which is controlled automatically in the same way. The method of claim 1, The membrane separation activated sludge method further includes a sludge solubilization tank 11 at the rear end of the membrane separation tank 5 so that a part of the highly concentrated sludge is solubilized in the sludge solubilization tank 11 and then the flow path changing device 2 Automatic control method of inflow control type membrane separation activated sludge process to be introduced into reactor in anoxic condition to be used as carbon source. The method according to claim 1 or 2, The NKP is an automatic control method of the inflow flow control membrane separation activated sludge process is detected when the change in the redox potential (dORP / dt) value of the batch reactor is minimum. The method of claim 3, wherein The NKP is an automatic control method of the inflow flow control membrane separation activated sludge process is detected in the range of the redox potential change (dORP / dt) of the batch reactor is -2 to -20 mV / min. The method of claim 3, wherein The phosphorus release time (t _e ) is preset in the range of 1 hour to 3 hours, or the time until the phosphorus concentration measured from the batch reactor reaches the target release concentration of 7 mg / L to 12 mg / L Automatic control method of inflow flow control type membrane separation activated sludge method. It includes a flow path changing device (2), Reactor A (3), Reactor B (4), Membrane separation tank (5), Reactor A (3) receives the sludge conveyed from the raw water and the membrane tank (5) through the flow path changer (2) to perform biological denitrification reaction under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) receives the sludge conveyed from the raw water and the separation membrane tank (5) by the step (S1) and the reaction tank B (4) is operated batchwise in the state that the external inflow is cut off through the flow path changing device (2) The organic material contained in the raw water is used as a carbon source to perform biological denitrification under anoxic conditions, and reactor A (3) is operated in a batchwise manner (S2) in which the external inflow is cut off. Immersion type separation membrane (6) is installed in the membrane separation tank (5) to concentrate the sludge and discharge the treated water at the same time, the highly concentrated sludge is to be circulated internally to the reaction tank in an oxygen-free condition through the flow path changing device (2) , As an automatic control method of inflow control type membrane separation activated sludge method that removes nitrogen and phosphorus simultaneously by repeatedly performing anoxic and anaerobic conditions, a) setting the step S1 operation time (T _a ) and the step S2 operation time (T _b ) to the same (T _a = T _b = T); b) detecting the NKP at the end of denitrification by measuring the ORP of the reactor operated batchwise in the step S1 or S2; c) measuring the elapsed time (t ₂ = Tt ₁ ) from the NKP detection (t ₁ ) until the operation time (T = Ta = Tb) of the step S1 or step S2; d) comparing the elapsed time (t ₂ ) with the phosphorus release time (t _e ) which is previously determined and obtained by measurement; And e) the elapsed time (t ₂₎ the operating time in this case is shorter than the the release time (t _e) such that longer than the elapsed time (t ₂₎ is the the release time (t _e) the step S1 and the step S2 ( Resetting T); Automatic control method of inlet flow control membrane separation activated sludge method comprising a. The method of claim 6, The NKP detection of step b) is the automatic control method of the inflow flow control membrane separation activated sludge process is carried out when the redox potential change (dORP / dt) value of the batch reactor is minimum. The method of claim 7, wherein The NKP detection of step b) is the automatic control method of the inflow flow control membrane separation activated sludge method is made in the range of the redox potential change (dORP / dt) value of the batch reactor in the range of -2 to -20 mV / min. The method of claim 6, The phosphorus release time t _e of step d) is preset in the range of 1 hour to 3 hours, or until the phosphorus concentration measured from the batch reactor reaches a target release concentration of 7 mg / L to 12 mg / L. Automatic control method of inflow flow control membrane separation activated sludge process. The method of claim 6, In step c), the inlet flow control type membrane separation activated sludge method for measuring the elapsed time t ₂ for each process cycle by repeating the process cycle 2T combining the steps S1 and S2 5 to 20 times. . It includes a flow path changing device (2), Reactor A (3), Reactor B (4), Membrane separation tank (5), Reactor A (3) receives the sludge conveyed from the raw water and the membrane tank (5) through the flow path changer (2) to perform biological denitrification reaction under anoxic conditions using organic matter contained in the raw water as a carbon source. , Reactor B (4) receives the sludge conveyed from the raw water and the separation membrane tank (5) by the step (S1) and the reaction tank B (4) is operated batchwise in the state that the external inflow is cut off through the flow path changing device (2) The organic material contained in the raw water is used as a carbon source to perform biological denitrification under anoxic conditions, and reactor A (3) is operated in a batchwise manner (S2) in which the external inflow is cut off. An immersion type separation membrane 6 is installed in the membrane separation tank 5 to concentrate the sludge and discharge the treated water at the same time. , It is an automatic control system of inflow flow control membrane separation activated sludge process that removes nitrogen and phosphorus simultaneously. An ORP sensor installed in any one or more of Reactor A or Reactor B to detect the denitrification time of the reactor operated in a batch of Step S1 or Step S2 to measure the redox potential inside the reactor; A timer for opening and closing the flow path changing device; A processor for determining the denitrification time (NKP) from the value (dORP / dt) input from the ORP sensor through the analog / digital converter and controlling the open / close control timer from the denitrification time and the effective anaerobic time required for phosphorus release; A digital input / output computer comprising; And An analog / digital converter (A / D converter) for converting an analog signal input from the ORP sensor and the open / close control timer into a digital signal and inputting the digital signal, and converting the digital signal output from the computer into an analog signal and outputting the analog signal; Flow control type membrane separation activated sludge method automatic control system comprising a. The method of claim 11, The system further includes a phosphorus concentration measuring device installed in any one or more of the reactor A or reactor B to determine the phosphorus release time of the reactor operated in a batch of step S1 or S2. Automatic control system of inflow flow control membrane separation activated sludge process.

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