CN114380386B - Automatic control method and device for external carbon source addition in sewage treatment - Google Patents

Automatic control method and device for external carbon source addition in sewage treatment Download PDF

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CN114380386B
CN114380386B CN202210075300.0A CN202210075300A CN114380386B CN 114380386 B CN114380386 B CN 114380386B CN 202210075300 A CN202210075300 A CN 202210075300A CN 114380386 B CN114380386 B CN 114380386B
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concentration
metering pump
scod
nitrate nitrogen
sewage treatment
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CN114380386A (en
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王晓东
吴宇行
陈宁
哈沙·拉特纳维拉
刘长青
毕学军
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Qingdao Daosikang Environmental Protection Technology Co ltd
Qingdao University of Technology
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Qingdao Daosikang Environmental Protection Technology Co ltd
Qingdao University of Technology
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    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/006—Regulation methods for biological treatment
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00—Biological treatment of water, waste water, or sewage
    • C02F3/02—Aerobic processes
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds
    • C02F2101/16—Nitrogen compounds, e.g. ammonia
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/30—Organic compounds
    • C02F2101/38—Organic compounds containing nitrogen
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/005—Processes using a programmable logic controller [PLC]
    • C02F2209/008—Processes using a programmable logic controller [PLC] comprising telecommunication features, e.g. modems or antennas
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/08—Chemical Oxygen Demand [COD]; Biological Oxygen Demand [BOD]
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/14—NH3-N
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/15—N03-N
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2209/00—Controlling or monitoring parameters in water treatment
    • C02F2209/40—Liquid flow rate
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00—Technologies for wastewater treatment
    • Y02W10/10—Biological treatment of water, waste water, or sewage

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Abstract

The invention relates to the field of sewage treatment, and provides an automatic control method and device for external carbon source addition in sewage treatment. The core of the automatic control method for external carbon source addition in sewage treatment is a mathematical model which is arranged in an intelligent addition control center, the intelligent addition control center, a signal input unit, a signal output unit, a power supply module and a remote transmission module jointly form an automatic control device for external carbon source addition in the sewage treatment denitrification process, the automatic control device can be in communication connection with an online monitoring instrument, collects data of the online monitoring instrument in real time to calculate the external carbon source addition amount and outputs the budget operation frequency; the automatic control device can be connected with the variable-frequency metering pump and outputs the real-time estimated running frequency to the metering pump, so that the adding amount of the external carbon source can be accurately controlled in real time. The system calculates the adding amount of the external carbon source in real time and automatically outputs the running frequency of the metering pump without manual control, so that the medicament cost and the manual control cost can be reduced.

Description

Automatic control method and device for external carbon source addition in sewage treatment
Technical Field
The invention relates to the technical field of sewage treatment, in particular to an automatic control method and device for external carbon source addition for sewage treatment.
Background
One of the main functions of a sewage treatment plant which takes domestic sewage as a main water inlet source is to greatly reduce nitrogen-containing substances in the sewage, organic nitrogen is converted into nitrogen after ammoniation, nitrification and denitrification in the biological denitrification process of the sewage, wherein a large amount of organic matters are required to provide electrons in the denitrification process, but the proportion of the water inlet organic matters to the total nitrogen is unbalanced, so that an external carbon source is required to be additionally added as an electron donor in the denitrification stage.
At present, sewage treatment plants generally adopt a mode of manually calculating the adding amount of the external carbon source and adding the external carbon source with a fixed amount to control the adding of the external carbon source, the method does not need complex equipment, but has the problems of control lag, incapability of coping with the fluctuation of the quality and the quantity of inlet water, incapability of meeting the growth requirement of microorganisms and the like, in addition, the excessive adding of the external carbon source for meeting the sewage discharge requirement improves the denitrification effect, on one hand, the waste of the carbon source is caused, the medicament cost is increased, on the other hand, the risk of exceeding the COD index of outlet water is caused, the excessive carbon source is recorded to be consumed in an aeration zone, the risk of destroying the nitrification capacity of an aerobic zone is caused, the electric energy consumption is increased, and the labor cost is also increased by frequently manually calculating the adding amount and regulating the excessive carbon source.
Disclosure of Invention
In order to solve the problems in the background art, the invention provides an automatic control method and a device for adding an external carbon source for sewage treatment, wherein the automatic control method comprises the following steps:
an automatic control method for adding an external carbon source for sewage treatment comprises the following steps:
s1: the signal input unit collects real-time data of the online instrument and transmits the data to the intelligent dosing control center;
s2: the intelligent dosing control center calculates the real-time dosing amount according to the real-time monitoring data and outputs the budget operating frequency; and is transmitted to the variable frequency metering pump through the signal output unit;
s3: the signal output unit downloads the estimated operation frequency to the variable-frequency metering pump;
s4: and the remote transmission module uploads the operating data to the cloud server side.
Further, the online monitoring data acquired in step S1 includes data acquired by the following meters: the water inlet ammonia nitrogen monitoring instrument is arranged in the water inlet channel; a nitrate nitrogen monitoring instrument arranged at the tail end of the anoxic zone; a dissolved oxygen monitoring instrument, an aerobic zone effluent nitrate nitrogen monitoring instrument and an aerobic zone effluent dissolved oxygen monitoring instrument are arranged at the reflux position of the aerobic zone; a nitrate nitrogen monitoring instrument for effluent of the biological pool arranged in the degassing area; and a nitrate nitrogen monitoring instrument for effluent of the secondary sedimentation tank.
Further, the specific process of step S3 includes:
the intelligent dosing control center adopts a calculation formula to calculate the operation frequency of the metering pump in real time, and realizes theoretical model correction by establishing multi-stage parameter feedback;
the sewage treatment device is characterized in that a front anoxic zone dosing point is arranged on a water inlet channel of the sewage treatment tank, a rear anoxic zone dosing point is arranged on the rear anoxic zone, and at least two variable-frequency metering pumps are arranged and are respectively connected to the front anoxic zone dosing point and the rear anoxic zone dosing point through pipelines and used for controlling the external carbon source dosing amount of the front anoxic zone dosing point and the rear anoxic zone dosing point; the calculation process of the frequency of the metering pump at the dosing point of the pre-anoxic zone is to calculate the real-time demand of the external carbon source according to the concentration of the nitrate nitrogen and the concentration of the Soluble Chemical Oxygen Demand (SCOD) of the water inlet of the anoxic zone and calculate the theoretical operating frequency of the metering pump according to the relation between the operating frequency of the pump and the dosing amount. The specific process comprises the following steps:
p1: obtaining the concentration NO of nitrate nitrogen in the return sludge of the secondary sedimentation tank according to the outlet nitrate nitrogen monitoring instrument of the secondary sedimentation tank 1 Acquiring the concentration NO of nitrate nitrogen in the internal reflux nitrification liquid according to the aerobic zone effluent nitrate nitrogen monitoring instrument 2 Obtaining the dissolved oxygen concentration DO of the internal reflux nitrifying liquid according to the dissolved oxygen monitoring instrument at the internal reflux position 1 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of dissolved oxygen can be converted into the concentration of nitrate, and the concentration NO of nitrate nitrogen in the inlet water of the anoxic zone can be calculated according to the ratio of the reflux times 3 ；
P2: note that the relation between nitrate nitrogen and SCOD electron transfer in the anoxic zone is beta 2 According to NO in step P1 3 Calculating the total required concentration SCOD of the anoxic zone SCOD 1 ；
P3: simulating intake SCOD concentration SCOD according to the reading of intake ammonia nitrogen monitoring instrument 2 SCOD in step P2 1 Concentration S of SCOD in inlet waterCOD 2 Obtaining SCOD concentration SCOD which needs to be added with external carbon source to increase 3 ；
P4: according to the running frequency of a metering pump and the SCOD concentration increment conversion coefficient beta of an added external carbon source anoxic zone 3 SCOD in step P3 3 Converting into the theoretical operating frequency of the metering pump, and correcting according to the ratio of the real-time inflow Flow to the biological pond design theory hourly inflow Flow Q, so as to obtain the theoretical frequency H of the metering pump at the dosing point of the pre-anoxic zone 1 The calculation formula is as follows:
Figure BDA0003483683650000031
in the formula:
h1 is the theoretical operating frequency of a metering pump at the dosing point of the preposed anoxic zone, and the unit is Hz;
NO 1 the concentration of nitrate in the returned sludge is mg/L, and the nitrate nitrogen is obtained by monitoring the nitrate nitrogen monitoring instrument 14 of the effluent of the secondary sedimentation tank in real time and transmitted to an automatic control device;
NO 2 the nitrate concentration of the reflux nitrification liquid is mg/L, and is obtained by monitoring the nitrate nitrogen monitoring instrument 10 of the effluent water of the aerobic zone in real time and transmitted to an automatic control device;
r is the internal reflux multiple, namely the ratio of the nitrifying liquid reflux amount to the sewage treatment amount, and the flow is obtained by monitoring the flow meter in real time and is transmitted to an automatic control device;
r is the external reflux multiple, namely the ratio of the reflux amount of the reflux sludge to the sewage treatment amount, and the flow is obtained by monitoring the flow meter in real time and is transmitted to an automatic control device;
β 1 determining the conversion coefficient of dissolved oxygen and nitrate radical through process debugging, wherein the value range is 0-1;
β 2 the conversion coefficient of nitrate and COD is determined by process debugging, and the value range is 0-10;
β 3 the conversion coefficient of the SCOD required concentration and the operation frequency of the metering pump is determined through process debugging, and the value range is 0-5;
SCOD 2 the unit of the intake SCOD analog quantity is mg/L, according to the time variation rule of soluble pollutants in domestic sewage, by actually measuring SCOD and ammonia nitrogen concentration in the sewage, a least square method is used for establishing a unitary linear regression model, and the intake ammonia nitrogen concentration is calculated by real-time monitoring;
flow is based on the real-time water inflow of the biological pool, the unit is m3/h, the Flow is obtained by real-time monitoring of a flowmeter and is transmitted to an automatic control device;
q is the flow rate of the biological pond in design hour and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond;
the multistage feedback parameters of the dosing point of the preposed anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; according to the real-time numerical value of the nitrate nitrogen monitoring instrument at the tail end of the anoxic zone, multiplying the calculation result of the theoretical formula by the corresponding feedback parameter in different concentration intervals, and realizing the correction of the calculation result of the theoretical formula;
the correction coefficient does not participate in the normal operation of the device, and the correction coefficient is manually adjusted when sudden conditions such as equipment failure, abnormal fluctuation of inlet water quality and the like occur during the operation of a sewage treatment plant so as to keep the device to operate stably;
the theoretical calculation process of the frequency of the metering pump at the dosing point of the postposition anoxic zone is as follows: calculating the real-time demand of the external carbon source according to the concentration of nitrate nitrogen in the effluent of the aerobic zone, and calculating the theoretical operating frequency of the metering pump according to the relation between the operating frequency of the pump and the dosing amount; the method specifically comprises the following steps:
q1: obtaining the concentration NO of nitrate nitrogen in effluent of the aerobic zone according to a nitrate nitrogen monitoring instrument at the tail end of the aerobic zone 4 Obtaining the dissolved oxygen concentration DO of the effluent of the aerobic zone according to a dissolved oxygen monitoring instrument at the tail end of the aerobic zone 2 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of the dissolved oxygen can be converted into the concentration of the nitrate, and the total concentration NO of the nitrate nitrogen in the effluent of the aerobic zone can be obtained by adding the concentration of the dissolved oxygen and the concentration of the nitrate 5 ；
Q2: the concentration of nitrate nitrogen in the effluent of the secondary sedimentation tank is set according to actual requirementsSetting value b, adding NO in step Q1 5 Reducing b to obtain the concentration NO of nitrate nitrogen to be removed in the back anoxic zone 6 ；
Q3: recording that the relation between nitrate nitrogen in the anoxic zone and SCOD electron transfer is beta 4 According to NO in step Q2 6 Calculating the total required concentration SCOD of the post-anoxic-zone SCOD 4 ；
Q4: according to the operating frequency of a metering pump and the increment conversion coefficient beta of the SCOD concentration of an anoxic zone after the addition of an external carbon source 5 SCOD in step Q3 4 Converting into the theoretical operating frequency of the metering pump, and correcting according to the ratio of the real-time inflow Flow to the biological pond design theory hourly inflow Flow Q, so as to obtain the theoretical frequency H of the metering pump at the dosing point of the post-anoxic zone 2 The calculation formula is as follows:
H 2 ＝(NO 4 +β 1 *DO 2 -b)*β 4 *β 5 *Flow/Q
in the formula:
H 2 the theoretical operating frequency of a rear metering pump is in Hz unit;
NO 4 the nitrate concentration of the effluent of the aerobic zone is mg/L, and the nitrate concentration is obtained by monitoring the nitrate nitrogen monitoring instrument of the effluent of the aerobic zone in real time and transmitted to an automatic control device;
DO 2 the concentration of the dissolved oxygen in the effluent water of the aerobic zone is mg/L, and the concentration is obtained by monitoring the dissolved oxygen in the effluent water of the aerobic zone in real time and transmitted to an automatic control device;
the Flow is the real-time water inflow of the biological pool, the unit is m/h, and the Flow is obtained by monitoring the Flow meter in real time and is transmitted to an automatic control device;
q is the flow rate of the biological pond in design hour and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond;
b is a set value constant of nitrate, the unit is mg/L, the set value constant is determined by the actual requirement of a sewage treatment plant, and the value range is 8-14;
beta 1 is a conversion coefficient of dissolved oxygen and nitrate radical, the coefficient is determined through process debugging, and the value range is 0-1;
beta 4 is a conversion coefficient of nitrate and COD, the coefficient is determined through process debugging, and the value range is 0-10;
beta 5 is the conversion coefficient of SCOD required concentration and the operation frequency of a metering pump, the coefficient is determined through process debugging, and the value range is 0-5;
the multistage feedback parameters of the dosing point of the post anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; multiplying the calculation result of the theoretical formula by corresponding feedback parameters in different concentration intervals according to the monitoring value of the online monitoring instrument for the nitrate nitrogen in the effluent of the biological pool, thereby realizing the correction of the calculation result of the theoretical formula;
the theoretical calculation formula of the output metering pump of the intelligent dosing control center is as follows:
A＝H*P*α
in the formula:
a is the actual operating frequency of the metering pump, the unit is Hz, and the calculated frequency is transmitted to a frequency converter and drives the metering pump to control the dosage;
h is the theoretical operating frequency of the metering pump, the unit is Hz, and the actual operating frequency of the metering pump is obtained after the calculation and multiplication of the feedback system adjusting parameter and the correction coefficient;
p is a feedback system adjusting parameter, and is determined according to process debugging, and the value range is 0-3;
alpha is a correction coefficient which is manually set when an emergency occurs in the operation process of the sewage treatment unit, the value range is 0-2, and the value of the sewage treatment unit is 1.0 when the sewage treatment unit operates normally.
The operation data in the step S4 includes, but is not limited to, water quality online monitoring data, operation frequency of the metering pump, operation state, and dosing flow data.
An automatic control device for sewage treatment external carbon source addition, the automatic control device comprises: the intelligent dosing control system comprises a signal input unit, an intelligent dosing control center, a signal output unit, a power supply module and a remote transmission module;
furthermore, the signal input unit is provided with an analog signal input terminal, a signal input integrated unit, an I/O integrated unit and a TCP/IP port; wherein: the input terminal collects monitoring data in real time to the signal input integrated unit and transmits the monitoring data to the intelligent dosing control center continuously through the I/O integrated unit and the TCP/IP port;
furthermore, a theoretical calculation formula is arranged in the intelligent dosing control center, the intelligent dosing control center calculates the real-time dosing amount according to real-time monitoring data, and outputs the budget operating frequency;
further, the signal output unit is provided with a TCP/IP port, an I/O integrated unit, a signal output integrated unit, an analog signal output terminal and a 220V/AC power output terminal; wherein: the intelligent control center multi-parameter control model outputs frequency signals which are transmitted to the metering pump through a TCP/IP port, an I/O integrated unit, a signal output integrated unit, an analog signal output terminal and a 220V/AC power output terminal in sequence;
furthermore, the power module is provided with a power master control switch, an AC/DC power adapter and a power strip and is used for controlling the power of the automatic control device to be switched on and off and converting alternating current into direct current so as to provide power for a microcomputer, an industrial router and an OPC server;
furthermore, a microcomputer, an industrial router and an OPC server in the automatic control device form a remote transmission module, wherein the microcomputer is used for data processing and remote transmission, the industrial router is used for connecting a network transmission medium, and the OPC server is used for data storage, transmission, remote monitoring and operation;
further, the automatic control device is provided with a remote transmission module, the remote transmission module uploads data such as water quality online monitoring data, operation frequency of a metering pump, an operation state and dosing flow to the cloud server, so that an operator can acquire the operation state of the device through the cloud server, analyze the data and optimally upgrade the system.
The invention achieves the following beneficial effects:
firstly, in the process of adding the external carbon source, the problem that the adding amount of the external carbon source cannot be automatically controlled in real time exists in the existing commonly-adopted control mode of manually calculating the adding amount of the external carbon source and adding the external carbon source with fixed amount.
Secondly, in the process of adding the external carbon source, the quality of the effluent reaches the standard by adopting an excessive adding method in a control mode of manually calculating the adding amount of the external carbon source and adding the external carbon source with a fixed amount, and the risk of damaging the stability of the biological treatment system exists.
Thirdly, the method can control the addition of the external carbon source according to the actual requirements in the sewage treatment process, avoids medicament waste caused by excessive addition of the external carbon source, and has the environmental benefits of saving medicament cost, reducing sludge yield, reducing greenhouse gas emission and the like.
And fourthly, in the process of adding the external carbon source, workers need to carry out water quality testing, calculate the dosage and adjust the adding amount of the external carbon source frequently.
Fifth, the nitrate nitrogen, ammonia nitrogen and dissolved oxygen on-line monitoring instrument required by the operation of the invention is a conventional installation instrument of a sewage treatment plant, and the construction cost of the biological pond on-line monitoring system is not increased.
Sixth, the invention uses the hardware such as the metering pump, various on-line monitoring instruments, programmable logic controller, etc. to adopt the existing mature market products, the structure is rational and easy to install, therefore the hardware device of the invention has reliability.
Seventh, the remote transmission module can transmit the operation data to the cloud, and a worker can analyze the operation effect of the system according to the operation data and perform system optimization, so that the operation effect of the system is continuously improved.
Drawings
FIG. 1 is a schematic diagram of the present invention in use;
FIG. 2 is a schematic view of the distribution of the on-line monitoring instruments of the present invention;
FIG. 3 is a schematic view of the automatic control device of the present invention;
FIG. 4 is a diagram showing the variation trend of the nitrate nitrogen at the tail end of an anoxic zone, the nitrate nitrogen at the effluent of an aerobic zone, the nitrate nitrogen at the effluent of a secondary sedimentation tank, the operation frequency of a metering pump at the dosing point of a postposition anoxic zone and the operation frequency of the dosing point of a preposition anoxic zone during 4-day operation of the invention.
Reference numbers in the figures:
1. an online monitoring instrument; 2. an automatic control device; 3. a signal input unit; 4. an intelligent dosing control center; 5. a signal output unit; 6. a power supply module; 7. a remote transmission module; 8. a metering pump; 9. a biological pond; 10. a cloud server; 11. a medicine adding point in the front anoxic zone; 12. an influent ammonia nitrogen monitoring instrument; 13. a nitrate nitrogen monitoring instrument at the tail end of the anoxic zone; 14. a dissolved oxygen monitoring instrument at the internal reflux position; 15. a nitrate nitrogen monitoring instrument for effluent of the aerobic zone; 16. an oxygen dissolving and oxygen dissolving monitoring instrument is arranged at the aerobic zone; 17. a medicine adding point in the anoxic zone is arranged at the rear part; 18. a nitrate nitrogen monitoring instrument for effluent of the biological pond; 19. a nitrate nitrogen monitoring instrument for effluent of the secondary sedimentation tank; 20. an analog signal input terminal; 21. a signal input integration unit; 22. I/O integrated unit, 23, TCP/IP port; 24. a signal output integration unit; 25. an analog signal output terminal; 26. 220V/AC power output terminal; 27. a power supply master control switch; 28. an AC/DC power adapter; 29. a power strip; 30. a microcomputer; 31. an industrial router; 32. and an OPC server.
Detailed Description
To facilitate an understanding of the invention for those skilled in the art, a specific embodiment thereof will be described below with reference to the accompanying drawings.
Referring to fig. 1 to 4, an automatic control device 2 for external carbon source addition in a denitrification process of sewage treatment comprises:
the signal input unit 3 is in communication connection with the online monitoring instrument 1, collects data of the online monitoring instrument 1 in real time, and transmits data signals to the intelligent dosing control center 4;
the intelligent dosing control center 4 calculates the real-time dosing amount according to the real-time monitoring data and outputs the budget operating frequency;
the signal output unit 5 outputs the estimated operating frequency according to the intelligent dosing control center 4 and downloads the estimated operating frequency to the variable-frequency metering pump 8;
the power supply module 6 controls the automatic control device 2 to be powered on and off, converts alternating current into direct current and provides power for other components of the automatic control device 2;
and the remote transmission module 7 is used for data processing, data storage, remote transmission, network transmission media and remote monitoring operation.
Still include cloud ware 10, programmable logic controller is provided with remote transmission module 7, remote transmission module 7 uploads data such as quality of water on-line monitoring data, measuring pump 8 operating frequency, running state, adds medicine flow to cloud ware 10, makes operator's accessible cloud ware 10 end data acquisition device running state, carries out data analysis and carries out optimization upgrading to the system.
The automatic control device 2 is provided with an analog signal input terminal 20, a signal input integrated unit 21, an I/O integrated unit, a TCP/IP port, a signal output integrated unit 24, an analog signal output terminal 25, a 220V/AC power output terminal 26, a power master control switch 27, an AC/DC power adapter 28, a power strip 29, a microcomputer 30, an industrial router 31 and an OPC server 32; wherein: the input terminal collects monitoring data in real time to the signal input integrated unit 21, and continues to transmit the monitoring data to the intelligent dosing control center 4 through the I/O integrated unit and the TCP/IP port, the multi-parameter control model of the control center calculates real-time dosing amount according to the real-time monitoring data and outputs budget operating frequency, and frequency signals are transmitted to the metering pump 8 through the TCP/IP port, the I/O integrated unit, the signal output integrated unit 24, the analog signal output terminal 25 and the 220V/AC power output terminal 26 in sequence; the power master control switch 27, the AC/DC power adapter 28 and the power strip 29 form a power module 6 for controlling the on/off of the power of the programmable logic controller and converting the AC power into the DC power to provide power for the microcomputer 30, the industrial router 31 and the OPC server 32.
The microcomputer 30, the industrial router 31 and the OPC server 32 in the automatic control device 2 form a remote transmission module 7, wherein the microcomputer 30 is used for data processing and remote transmission, the industrial router 31 is used for connecting a network transmission medium, and the OPC server 32 is used for data storage, transmission, remote monitoring and operation.
An automatic control method for external carbon source addition in sewage treatment is carried out according to the following steps:
s1: the signal input unit 3 collects real-time data of an online instrument and transmits the data to the intelligent dosing control center 4;
s2: the intelligent dosing control center 4 calculates the real-time dosing amount according to the real-time monitoring data and outputs the budget operating frequency; and is transmitted to the variable frequency metering pump 8 through the signal output unit 5;
s3: the signal output unit 5 downloads the estimated operation frequency to the variable-frequency metering pump 8;
s4: the remote transmission module 7 uploads the operation data to the cloud server 10.
The online monitoring data acquired in step S1 includes data acquired by the following instruments: the water inlet ammonia nitrogen monitoring instrument 12 is arranged in the water inlet channel; a nitrate nitrogen monitoring instrument 13 arranged at the tail end of the anoxic zone; a dissolved oxygen monitoring instrument, an aerobic zone effluent nitrate nitrogen monitoring instrument 15 and an aerobic zone effluent dissolved oxygen monitoring instrument 16 are arranged at the reflux part of the aerobic zone; a nitrate nitrogen monitoring instrument 18 arranged in the effluent of the biological pond in the degassing area; and a nitrate nitrogen monitoring instrument 19 arranged at the effluent of the secondary sedimentation tank.
The specific process of step S3 includes:
the intelligent dosing control center 4 calculates the running frequency of the metering pump 8 in real time by adopting a calculation formula, and realizes theoretical model correction by establishing multi-stage parameter feedback;
a water inlet channel of the sewage treatment tank is provided with a front anoxic zone dosing point 11, a rear anoxic zone dosing point 17, and at least two variable frequency metering pumps 8 are arranged and are respectively connected to the front anoxic zone dosing point 11 and the rear anoxic zone dosing point 17 through pipelines and used for controlling the external carbon source dosing amount of the front anoxic zone dosing point 11 and the rear anoxic zone dosing point 17; the calculation process of the frequency of the metering pump 8 at the dosing point 11 of the preposed anoxic zone is to calculate the real-time demand of the external carbon source according to the concentration of nitrate nitrogen and the concentration of Soluble Chemical Oxygen Demand (SCOD) of inlet water in the anoxic zone, and calculate the theoretical operating frequency of the metering pump 8 according to the relationship between the operating frequency of the pump and the dosing amount.
The method specifically comprises the following steps:
p1: the concentration NO of nitrate nitrogen in the return sludge of the secondary sedimentation tank is obtained by a nitrate nitrogen monitoring instrument 19 at the outlet of the secondary sedimentation tank 1 According to the nitrate nitrogen monitoring instrument 15 of the effluent water of the aerobic zone, the concentration NO of the nitrate nitrogen in the internal reflux nitrification liquid is obtained 2 Obtaining the dissolved oxygen concentration DO of the internal reflux nitrifying liquid according to the dissolved oxygen monitoring instrument 14 at the internal reflux position 1 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of dissolved oxygen can be converted into the concentration of nitrate, and the concentration NO of nitrate nitrogen of inlet water in the anoxic zone can be calculated according to the ratio of the reflux times 3 ；
P2: note that the relation between nitrate nitrogen and SCOD electron transfer in the anoxic zone is beta 2 According to NO in step P1 3 Calculating the total required concentration SCOD of the anoxic zone SCOD 1 ；
P3: simulating the concentration SCOD of the intake water according to the reading of the intake water ammonia nitrogen monitoring instrument 12 2 Step P2 of SCOD 1 Concentration SCOD of inlet water 2 Obtaining the SCOD concentration SCOD which needs to be added with an external carbon source to increase 3 ；
P4: according to the running frequency of a metering pump 8 and the SCOD concentration increment conversion coefficient beta of an added external carbon source anoxic zone 3 SCOD in step P3 3 Converted into the theoretical operating frequency of the metering pump 8, and corrected according to the ratio of the real-time inflow Flow to the theoretical hourly inflow Q of the biological pond 9, so that the dosing point 11 of the pre-anoxic zone is the theoretical frequency H of the metering pump 8 1 The calculation formula is as follows:
Figure BDA0003483683650000101
in the formula:
h1 is the theoretical operating frequency of a metering pump 8 at a front anoxic zone dosing point 11, and the unit is Hz;
NO 1 for refluxing sludge with nitric acidThe salt concentration is in mg/L, is obtained by monitoring the effluent nitrate nitrogen monitoring instrument 19 of the secondary sedimentation tank in real time and is transmitted to the automatic control device 2;
NO 2 the nitrate concentration of the reflux nitrification liquid is mg/L, and is obtained by monitoring the nitrate nitrogen monitoring instrument 15 of the effluent of the aerobic zone in real time and transmitted to the automatic control device 2;
r is the internal reflux multiple, namely the ratio of the nitrifying liquid reflux to the sewage treatment capacity, and the flow is obtained by real-time monitoring of a flowmeter and is transmitted to the automatic control device 2;
r is the external reflux multiple, namely the ratio of the reflux amount of the reflux sludge to the sewage treatment amount, and the flow is obtained by monitoring the flow meter in real time and is transmitted to the automatic control device 2;
β 1 determining the conversion coefficient of dissolved oxygen and nitrate radical through process debugging, wherein the value range is 0-1;
β 2 the conversion coefficient of nitrate and COD is determined by process debugging, and the value range is 0-10;
β 3 the conversion coefficient of the SCOD required concentration and the operation frequency of the metering pump 8 is determined through process debugging, and the value range is 0-5;
SCOD 2 the unit of the intake SCOD analog quantity is mg/L, according to the time variation rule of soluble pollutants in domestic sewage, by actually measuring SCOD and ammonia nitrogen concentration in the sewage, a least square method is used for establishing a unitary linear regression model, and the intake ammonia nitrogen concentration is calculated by real-time monitoring;
flow is the real-time water inflow of the biological pool 9, the unit is m/h, the Flow is obtained by real-time monitoring of a flowmeter and is transmitted to the automatic control device (2);
q is the designed hourly flow rate of the biological pond 9 and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond 9;
the front anoxic zone dosing point 11 multistage feedback parameters are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; according to the real-time numerical value of the nitrate nitrogen monitoring instrument 1313 at the tail end of the anoxic zone, multiplying the calculation result of the theoretical formula by the corresponding feedback parameter in different concentration intervals to realize the correction of the calculation result of the theoretical formula;
the correction coefficient does not participate in the normal operation of the device, and is manually adjusted when sudden conditions such as equipment failure, abnormal fluctuation of inlet water quality and the like occur during the operation of a sewage treatment plant so as to keep the device to operate stably;
the theoretical calculation process of the frequency of the metering pump 8 at the dosing point 17 of the postposition anoxic zone is as follows: calculating the real-time demand of the external carbon source according to the concentration of nitrate nitrogen in the effluent of the aerobic zone, and calculating the theoretical operating frequency of the metering pump 8 according to the relation between the operating frequency of the pump and the dosing amount; the method specifically comprises the following steps:
q1: obtaining the concentration NO of nitrate nitrogen in effluent of the aerobic zone according to a nitrate nitrogen monitoring instrument at the tail end of the aerobic zone 4 Obtaining the dissolved oxygen concentration DO of the water discharged from the aerobic zone according to a dissolved oxygen monitoring instrument at the tail end of the aerobic zone 2 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of the dissolved oxygen can be converted into the concentration of nitrate, and the total concentration NO of the nitrate nitrogen in the effluent of the aerobic zone can be obtained by adding the concentration of the dissolved oxygen and the concentration of the nitrate 5 ；
Q2: setting a nitrate nitrogen concentration set value b of effluent of the secondary sedimentation tank according to actual requirements, and adding NO in the step Q1 5 The nitrate nitrogen concentration NO to be removed in the post anoxic zone can be obtained by reducing b 6 ；
Q3: recording that the relation between nitrate nitrogen in the anoxic zone and SCOD electron transfer is beta 4 According to NO in step Q2 6 Calculating the total required concentration SCOD of the SCOD in the post-anoxic zone 4 ；
Q4: according to the running frequency of a metering pump 8 and the increment conversion coefficient beta of the concentration of the SCOD in the anoxic zone after the external carbon source is added 5 SCOD in step Q3 4 Converted into the theoretical operating frequency of the metering pump 8, and corrected according to the ratio of the real-time inflow Flow to the hourly inflow Q of the biological pond 9 design theory, so that the dosing point 17 of the back anoxic zone is the theoretical frequency H of the metering pump 8 2 The calculation formula is as follows:
H 2 ＝(NO 4 +β 1 *DO 2 -b)*β 4 *β 5 *Flow/Q
in the formula:
H 2 the theoretical operating frequency of the rear metering pump 8 is in Hz;
NO 4 the nitrate concentration of the effluent of the aerobic zone is mg/L, and the nitrate concentration is obtained by monitoring the nitrate nitrogen monitoring instrument 15 of the effluent of the aerobic zone in real time and transmitted to the automatic control device 2;
DO 2 the concentration of the dissolved oxygen in the effluent water of the aerobic zone is mg/L, and the concentration is obtained by monitoring the concentration of the dissolved oxygen in the effluent water of the aerobic zone by a monitoring instrument 16 in real time and is transmitted to an automatic control device 2;
the Flow is the real-time water inflow of the biological pool 9, the unit is m/h, the Flow is obtained by real-time monitoring of a flowmeter and is transmitted to the automatic control device 2;
q is the designed hourly flow rate of the biological pond 9 and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond 9;
b is a set value constant of nitrate, the unit is mg/L, the set value constant is determined by the actual requirement of a sewage treatment plant, and the value range is 8-14;
beta 1 is a conversion coefficient of dissolved oxygen and nitrate radical, and the coefficient is determined through process debugging, and the value range is 0-1;
beta 4 is a conversion coefficient of nitrate and COD, the coefficient is determined through process debugging, and the value range is 0-10;
beta 5 is the conversion coefficient of SCOD required concentration and the operation frequency of the metering pump 8, and the coefficient is determined through process debugging, and the value range is 0-5;
the multistage feedback parameters of the dosing point 17 of the post anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; according to the monitoring value of the nitrate nitrogen on-line monitoring instrument 1 of the effluent of the biological pond 9, multiplying the calculation result of the theoretical formula by corresponding feedback parameters in different concentration intervals to realize the correction of the calculation result of the theoretical formula;
the theoretical calculation formula of the output metering pump 8 of the intelligent dosing control center 4 is as follows:
A＝H*P*α
in the formula:
a is the actual operating frequency of the metering pump 8, the unit is Hz, and the calculated frequency is transmitted to a frequency converter and drives the metering pump 8 to control the dosage;
h is the theoretical operating frequency of the metering pump 8, the unit is Hz, and the actual operating frequency of the metering pump 8 is obtained after the calculation and multiplication of the feedback system adjusting parameter and the correction coefficient;
p is a feedback system adjusting parameter, and is determined according to process debugging, and the value range is 0-3;
alpha is a correction coefficient which is manually set when an emergency occurs in the operation process of the sewage treatment unit, the value range is 0-2, and the value of the sewage treatment unit is 1.0 when the sewage treatment unit operates normally.
The operation data in the step S4 includes, but is not limited to, water quality online monitoring data, operation frequency of the metering pump 8, operation state, and dosing flow data.
The invention is further illustrated by the following examples in connection with the accompanying drawings.
Example 1:
the carbon source intelligent adding control device firstly collects operation data of a biological pond 9 through an online monitoring instrument 1, wherein the online monitoring instrument 1 comprises an intake ammonia nitrogen monitoring instrument 12 arranged in an intake channel; a nitrate nitrogen monitoring instrument 13 arranged at the tail end of the anoxic zone; a dissolved oxygen monitoring instrument, an aerobic zone effluent nitrate nitrogen monitoring instrument 15 and an aerobic zone effluent dissolved oxygen monitoring instrument 16 are arranged at the reflux part of the aerobic zone; a nitrate nitrogen monitoring instrument 18 arranged in the effluent of the biological pond in the degassing area; and a nitrate nitrogen monitoring instrument 19 is arranged at the effluent of the secondary sedimentation tank. Biological pond 9 is provided with leading anoxic zone dosing point 11 including water inlet channel, mixing zone, anoxic zone, aerobic zone, back anoxic zone, back aerobic zone, degasification district, two heavy ponds, at biological pond 9's water inlet channel, and back anoxic zone is provided with rearmounted anoxic zone dosing point 17.
The on-line monitoring data is transmitted to a signal input unit 3 inside the automatic control device 2 in a wireless network transmission mode and is transmitted to an intelligent dosing control center 4, and a theoretical formula of two dosing points, namely a front-mounted anoxic zone dosing point 11 and a rear-mounted anoxic zone dosing point 17, is arranged in the intelligent dosing control center 4. The real-time theoretical operating frequency of the metering pump 8 is calculated by a theoretical formula arranged in the intelligent dosing control center 4, and is transmitted to a frequency converter of the metering pump 8 through the signal output unit 5, and the output frequency is adjusted, so that the control of the dosing amount of the external carbon source is realized. Metering pumps 8 are arranged, two metering pumps 8 are respectively used for feeding external carbon sources to a front anoxic zone feeding point 11 and a rear anoxic zone feeding point 17, and the third metering pump 8 is used as a standby pump. The remote transmission module 7 can upload data such as water quality online monitoring data, the operating frequency and the operating state of the metering pump 8, the dosing flow and the like to the cloud server 10, so that an operator can acquire the operating state of the device through the data acquisition device at the cloud server 10, analyze the data and optimize and upgrade the system.
Example 2
By adopting the device described in example 1, the concentration interval and the feedback parameters of the multi-stage feedback parameters of the feeding point 11 of the pre-anoxic zone are shown in the table 1. It can be seen from table 1 that the multistage feedback parameters of the dosing point 17 of the post-anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, when the real-time numerical value of the nitrate nitrogen monitoring instrument 18 of effluent of the biological pond is between 10mg/L and 11mg/L, the feedback parameters are 1.00, so that the frequency theoretical calculation formula of the dosing point 17 of the post-anoxic zone is required to be multiplied by 1.00, and the correction coefficient is 1.00 when the sewage treatment unit normally operates, so that the actual frequency result of the dosing point 17 of the post-anoxic zone is the calculation result of the theoretical calculation formula multiplied by 1.00; when the real-time numerical value of the nitrate nitrogen monitoring instrument 18 of the effluent of the biological pond is between 11mg/L and 11.80mg/L, the feedback parameter is 1.30, so that the frequency theoretical calculation formula of the metering pump 8 at the dosing point 17 of the post-anoxic zone needs to be multiplied by 1.30, and the correction coefficient is 1.00 when the sewage treatment unit normally operates, so that the actual frequency result of the metering pump 8 at the dosing point 17 of the post-anoxic zone is the calculation result of the theoretical calculation formula multiplied by 1.30 by 1.00, and the correction of the theoretical calculation result is realized.
Example 3
The actual operation was carried out in a biological pond 9 of a sewage treatment plant using the apparatus described in example 1. As can be seen from FIG. 4, the frequency of the metering pump 8 changes along with the change of the real-time monitoring data of the nitrate nitrogen on-line monitoring instrument 1, which indicates that the device can regulate and control the running frequency of the metering pump 8 in real time according to the change of the reading of the on-line monitoring instrument 1. As can be seen from Table 2, the addition amount of the external carbon source per ton of inlet water after the operation of the invention is reduced by 21.2 percent compared with the same period before the operation. Therefore, the invention can realize the real-time calculation of the carbon source adding amount, automatically regulate and control the running frequency of the metering pump 8 and reduce the adding amount.
Table 1: rear anoxic zone dosing point 17 multi-stage feedback parameter concentration interval and feedback parameter table
Feedback interval Feedback parameter
2.30
13.80mg/L
2.00
13.00mg/L
1.65
12.30mg/L
1.50
11.80mg/L
1.30
11.00mg/L
1.00
10.00mg/L
0.70
9.00mg/L
0.50
Table 2: comparison table of synchronous operation effect between 2021 year operation period and 2020 year
Figure BDA0003483683650000141
The above embodiments of the present invention do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims (3)

1. An automatic control method for external carbon source addition in sewage treatment is characterized by comprising the following steps:
the intelligent dosing control system comprises an S1 signal input unit (3) and an intelligent dosing control center (4), wherein the signal input unit collects real-time data of an online instrument and transmits the data to the intelligent dosing control center;
s2: the intelligent dosing control center (4) calculates the real-time dosing amount according to the real-time monitoring data and outputs the budget operating frequency; and is transmitted to the variable frequency metering pump through the signal output unit;
s3: the signal output unit (5) downloads the budget operating frequency to the variable-frequency metering pump;
s4: the remote transmission module (7) uploads the operation data to the cloud server end (10);
the specific process of the step S3 includes:
the intelligent dosing control center (4) adopts a calculation formula to calculate the operation frequency of the metering pump in real time, and realizes theoretical model correction by establishing multi-stage parameter feedback;
a water inlet channel of the sewage treatment tank is provided with a front anoxic zone dosing point (11), a rear anoxic zone dosing point (17), at least two variable frequency metering pumps (8) are arranged and are respectively connected to the front anoxic zone dosing point (11) and the rear anoxic zone dosing point (17) through pipelines and used for controlling the external carbon source dosing amount of the front anoxic zone dosing point (11) and the rear anoxic zone dosing point (17); wherein the calculation process of the frequency of the metering pump of the preposed anoxic zone dosing point (11) is to calculate the real-time demand of an external carbon source according to the concentration of nitrate nitrogen and the concentration of Soluble Chemical Oxygen Demand (SCOD) of inlet water of the anoxic zone and calculate the theoretical operating frequency of the metering pump according to the relationship between the operating frequency of the pump and the dosing amount; the method specifically comprises the following steps:
p1: obtaining the second water according to the nitrate nitrogen monitoring instrument (19) of the effluent of the second sedimentation tankConcentration of nitrate nitrogen NO in sludge returned from settling tank 1 According to the nitrate nitrogen monitoring instrument (15) of the effluent water of the aerobic zone, the concentration NO of the nitrate nitrogen of the internal reflux nitrification liquid is obtained 2 Obtaining the dissolved oxygen concentration DO of the internal reflux nitrified liquid according to the dissolved oxygen monitoring instrument (14) at the internal reflux position 1 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of dissolved oxygen can be converted into the concentration of nitrate, and the concentration NO of nitrate nitrogen of inlet water in the anoxic zone can be calculated according to the ratio of the reflux times 3 ；
P2: note that the relation between nitrate nitrogen and SCOD electron transfer in the anoxic zone is beta 2 According to NO in step P1 3 Calculating the total required concentration SCOD of the anoxic zone SCOD 1 ；
P3: simulating the concentration SCOD of the intake water according to the reading of the intake water ammonia nitrogen monitoring instrument (12) 2 SCOD in step P2 1 Reducing SCOD concentration of influent SCOD 2 Obtaining the SCOD concentration SCOD which needs to be added with an external carbon source to increase 3 ；
P4: according to the running frequency of a metering pump and the SCOD concentration increment conversion coefficient beta of an anoxic zone for adding an external carbon source 3 SCOD in step P3 3 Converting into the theoretical operating frequency of the metering pump, and correcting according to the ratio of the real-time inflow Flow to the hourly inflow Q of the biological pond design theory, so as to obtain the theoretical frequency H of the metering pump at the dosing point of the pre-anoxic zone 1 The calculation formula is as follows:
Figure FDA0004047429270000021
in the formula:
h1 is the theoretical operating frequency of a dosing point metering pump in the front anoxic zone, and the unit is Hz;
NO 1 the concentration of nitrate in the returned sludge is mg/L, and the nitrate nitrogen is obtained by monitoring the nitrate nitrogen monitoring instrument (19) of the effluent of the secondary sedimentation tank in real time and transmitted to the automatic control device (2);
NO 2 the nitrate concentration of the reflux nitrification liquid is mg/L, and is obtained by monitoring the nitrate nitrogen monitoring instrument (15) of the effluent water of the aerobic zone in real time and transmitted to the automatic control device (2);
r is the internal reflux multiple, namely the ratio of the nitrifying liquid reflux to the sewage treatment capacity, and the flow is obtained by real-time monitoring of a flowmeter and is transmitted to the automatic control device (2);
r is the external reflux multiple, namely the ratio of the reflux amount of the reflux sludge to the sewage treatment amount, and the flow is obtained by monitoring the flow meter in real time and is transmitted to the automatic control device (2);
β 1 determining the conversion coefficient of dissolved oxygen and nitrate radical through process debugging, wherein the value range is 0-1;
β 2 the conversion coefficient of nitrate and COD is determined by process debugging, and the value range is 0-10;
β 3 the conversion coefficient of the SCOD required concentration and the operation frequency of the metering pump is determined through process debugging, and the value range is 0-5;
SCOD 2 the intake SCOD analog quantity is in mg/L, and according to the time variation rule of soluble pollutants in domestic sewage, an unitary linear regression model is established by actually measuring SCOD and ammonia nitrogen concentration in the sewage by using a least square method and is calculated by the intake ammonia nitrogen concentration monitored in real time;
the flow is the real-time water inflow of the biological pool, the unit is m/h, and the flow is obtained by monitoring the flow meter in real time and is transmitted to the automatic control device (2);
q is the flow rate of the biological pond in design hour and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond;
the multistage feedback parameters of the dosing point of the pre-anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; according to the real-time numerical value of a nitrate nitrogen monitoring instrument (13) at the tail end of the anoxic zone, multiplying the calculation result of the theoretical formula by corresponding feedback parameters in different concentration intervals to realize the correction of the calculation result of the theoretical formula;
the correction coefficient does not participate in the normal operation of the device, and is manually adjusted when sudden conditions such as equipment failure, abnormal fluctuation of inlet water quality and the like occur during the operation of a sewage treatment plant so as to keep the device to operate stably;
the theoretical calculation process of the frequency of the metering pump at the dosing point of the postposition anoxic zone is as follows: calculating the real-time demand of the external carbon source according to the concentration of nitrate nitrogen in the effluent of the aerobic zone, and calculating the theoretical operating frequency of the metering pump according to the relation between the operating frequency of the pump and the dosing amount; the method specifically comprises the following steps:
q1: the concentration NO of nitrate nitrogen in effluent of the aerobic zone is obtained according to a nitrate nitrogen monitoring instrument (15) at the tail end of the aerobic zone 4 Obtaining the dissolved oxygen concentration DO of the water discharged from the aerobic zone according to a dissolved oxygen monitoring instrument (16) at the tail end of the aerobic zone 2 The ratio of the nitrate nitrogen to the dissolved oxygen as the electron donor to the electron acceptor is beta 1 Therefore, the concentration of the dissolved oxygen can be converted into the concentration of the nitrate, and the total concentration NO of the nitrate nitrogen in the effluent of the aerobic zone can be obtained by adding the concentration of the dissolved oxygen and the concentration of the nitrate 5 ；
Q2: setting a nitrate nitrogen concentration set value b of effluent of the secondary sedimentation tank according to actual requirements, and adding NO in the step Q1 5 The nitrate nitrogen concentration NO to be removed in the post anoxic zone can be obtained by reducing b 6 ；
Q3: recording that the relation between nitrate nitrogen in the anoxic zone and SCOD electron transfer is beta 4 According to NO in step Q2 6 Calculating the total required concentration SCOD of the SCOD in the post-anoxic zone 4 ；
Q4: according to the operating frequency of a metering pump and the increment conversion coefficient beta of the SCOD concentration of an anoxic zone after the addition of an external carbon source 5 SCOD in step Q3 4 Converting into the theoretical operating frequency of the metering pump, and correcting according to the ratio of the real-time inflow Flow to the biological pond design theory hourly inflow Flow Q, so as to obtain the theoretical frequency H of the metering pump at the dosing point of the post-anoxic zone 2 The calculation formula is as follows:
H 2 ＝(NO 4 +β 1 *DO 2 -b)*β 4 *β 5 *Flow/Q
in the formula:
H 2 the theoretical operation frequency of a rear metering pump is in Hz;
NO 4 the nitrate concentration of the effluent of the aerobic zone is mg/L, and the nitrate concentration is obtained by monitoring the nitrate nitrogen monitoring instrument (15) of the effluent of the aerobic zone in real time and transmitted to the automatic control device (2);
DO 2 the concentration of the dissolved oxygen in the effluent water of the aerobic zone is mg/L, and the concentration is obtained by monitoring the dissolved oxygen in the effluent water of the aerobic zone by a monitoring instrument (16) in real time and is transmitted to an automatic control device (2);
the flow is the real-time water inflow of the biological pool, the unit is m/h, and the flow is obtained by monitoring the flow meter in real time and is transmitted to the automatic control device (2);
q is the flow rate of the biological pond in design hour and is m 3 The water intake is determined by dividing 24 according to the design daily water intake of the biological pond;
b is a set value constant of nitrate, the unit is mg/L, the set value constant is determined by the actual requirement of a sewage treatment plant, and the value range is 8-14;
beta 1 is a conversion coefficient of dissolved oxygen and nitrate radical, and the coefficient is determined through process debugging, and the value range is 0-1;
beta 4 is a conversion coefficient of nitrate and COD, the coefficient is determined through process debugging, and the value range is 0-10;
beta 5 is the conversion coefficient of SCOD required concentration and the operation frequency of a metering pump, the coefficient is determined through process debugging, and the value range is 0-5;
the multistage feedback parameters of the dosing point of the post anoxic zone are provided with 9 concentration intervals and 8 feedback parameters, wherein the concentration intervals are determined according to the sewage treatment standard executed by a sewage treatment plant, the feedback parameters are determined by process debugging, and the value range is 0-3; according to the monitoring value of the on-line monitoring instrument for the nitrate nitrogen in the effluent of the biological pond, multiplying the calculation result of the theoretical formula by corresponding feedback parameters in different concentration intervals to realize the correction of the calculation result of the theoretical formula;
the theoretical calculation formula of the output metering pump of the intelligent dosing control center 4 is as follows:
A＝H*P*α
in the formula:
a is the actual operating frequency of the metering pump, the unit is Hz, and the calculated frequency is transmitted to a frequency converter and drives the metering pump to control the dosage;
h is the theoretical operating frequency of the metering pump, the unit is Hz, and the actual operating frequency of the metering pump is obtained after the calculation and multiplication of the feedback system adjusting parameter and the correction coefficient;
p is a feedback system adjusting parameter, and is determined according to process debugging, and the value range is 0-3;
alpha is a correction coefficient which is manually set when an emergency occurs in the operation process of the sewage treatment unit, the value range is 0-2, and the value of the sewage treatment unit is 1.0 when the sewage treatment unit operates normally.
2. The automatic control method for the external carbon source addition in sewage treatment according to claim 1, characterized in that: the online monitoring data collected by the signal input unit (3) in the step S1 comprises data acquired by the following instruments: the inlet ammonia nitrogen monitoring instrument (12) is arranged in the inlet channel; a nitrate nitrogen monitoring instrument (13) arranged at the tail end of the anoxic zone; a dissolved oxygen monitoring instrument (15) arranged at the reflux part of the aerobic zone, a nitrate nitrogen monitoring instrument (15) for the effluent of the aerobic zone and a dissolved oxygen monitoring instrument (16) for the effluent of the aerobic zone; a nitrate nitrogen monitoring instrument (18) arranged in the effluent of the biological pool in the degassing area; and a nitrate nitrogen monitoring instrument (19) arranged at the effluent of the secondary sedimentation tank.
3. The automatic control method for external carbon source addition in sewage treatment according to claim 1, characterized in that: the operation data in the step S4 includes, but is not limited to, water quality online monitoring data, operation frequency of the metering pump, operation state, and dosing flow data.
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