CN113149242B - Dissolved oxygen control device and method for sewage treatment system - Google Patents
Dissolved oxygen control device and method for sewage treatment system Download PDFInfo
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- CN113149242B CN113149242B CN202110326663.2A CN202110326663A CN113149242B CN 113149242 B CN113149242 B CN 113149242B CN 202110326663 A CN202110326663 A CN 202110326663A CN 113149242 B CN113149242 B CN 113149242B
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- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 title claims abstract description 162
- 239000001301 oxygen Substances 0.000 title claims abstract description 162
- 229910052760 oxygen Inorganic materials 0.000 title claims abstract description 162
- 239000010865 sewage Substances 0.000 title claims abstract description 73
- 238000000034 method Methods 0.000 title claims abstract description 50
- 238000005273 aeration Methods 0.000 claims abstract description 363
- 230000001105 regulatory effect Effects 0.000 claims abstract description 195
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 54
- 230000001276 controlling effect Effects 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims abstract description 14
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims description 68
- 239000007789 gas Substances 0.000 claims description 55
- 238000012937 correction Methods 0.000 claims description 24
- 238000004062 sedimentation Methods 0.000 claims description 23
- 241000894006 Bacteria Species 0.000 claims description 16
- 238000010992 reflux Methods 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 8
- 230000005540 biological transmission Effects 0.000 claims description 6
- 230000008054 signal transmission Effects 0.000 claims description 6
- 238000009792 diffusion process Methods 0.000 claims description 4
- 229920006395 saturated elastomer Polymers 0.000 claims description 4
- 239000010802 sludge Substances 0.000 claims description 4
- 230000008569 process Effects 0.000 abstract description 4
- 230000008859 change Effects 0.000 description 5
- WHBHBVVOGNECLV-OBQKJFGGSA-N 11-deoxycortisol Chemical compound O=C1CC[C@]2(C)[C@H]3CC[C@](C)([C@@](CC4)(O)C(=O)CO)[C@@H]4[C@@H]3CCC2=C1 WHBHBVVOGNECLV-OBQKJFGGSA-N 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000007363 regulatory process Effects 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
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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
- C02F7/00—Aeration of stretches of water
-
- 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
- C02F2209/22—O2
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- 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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- Life Sciences & Earth Sciences (AREA)
- Hydrology & Water Resources (AREA)
- Engineering & Computer Science (AREA)
- Environmental & Geological Engineering (AREA)
- Water Supply & Treatment (AREA)
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Activated Sludge Processes (AREA)
Abstract
The invention discloses a dissolved oxygen control device and a dissolved oxygen control method for a sewage treatment system, which relate to the technical field of sewage treatment, and the method comprises the following steps: measuring the sewage flow by using a liquid flowmeter, and calculating the water lag time according to the sewage flowmeter within a set time; respectively obtaining a second required aeration amount and a third required aeration amount of the second aeration tank and the third aeration tank in a set time period; each time the second required aeration amount and the third required aeration amount are obtained, and after the water lag time is elapsed, the second actual air supply amount in the second aeration tank and the third actual air supply amount in the third aeration tank are obtained; controlling the opening of the second regulating valve and the opening of the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively; the method utilizes the device to precisely control the dissolved oxygen in the aeration tank of the sewage treatment system at regular time, and can ensure the stable and efficient operation of the sewage treatment process.
Description
Technical Field
The invention belongs to the technical field of sewage treatment, and particularly relates to a dissolved oxygen control device and method for a sewage treatment system.
Background
The sewage treatment plant generally adopts a control system to realize the standard operation of a sewage denitrification and dephosphorization process system, wherein the dissolved oxygen is an important index for controlling the operation of the sewage denitrification and dephosphorization process. The control system of the existing sewage treatment plant completely depends on the reliability of a monitoring instrument, and the existing online instrument has higher price and more complex maintenance management, so that the investment cost and daily maintenance cost for directly utilizing the online instrument to control the dissolved oxygen are obviously increased; in addition, once the dissolved oxygen meters in the control systems cannot be maintained in time, the dissolved oxygen control systems of the corresponding units cannot work normally, and the stability of other units is affected; along with the increasingly strict requirements of the water quality of the water, the water quality of the water is required to reach the standard in real time, the water quality of the water is required to be monitored and fed back in time, and the popularization and application of the dissolved oxygen control system are greatly affected due to the high investment and operation cost and unstable system operation of the existing control system.
Disclosure of Invention
The invention aims at overcoming the defects in the prior art, and provides a dissolved oxygen control device and a dissolved oxygen control method for a sewage treatment system.
In order to achieve the above object, the present invention provides a dissolved oxygen control apparatus for a sewage treatment system including a non-aeration tank, a first aeration tank, a second aeration tank, a third aeration tank, and a secondary sedimentation tank, which are sequentially disposed from front to rear, characterized in that the apparatus comprises:
a liquid flowmeter arranged in the non-aeration tank;
the first dissolved oxygen meter and the second dissolved oxygen meter are respectively arranged in the second aeration tank and the third aeration tank;
the ammonia nitrogen monitor is arranged in the secondary sedimentation tank;
the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the control unit is connected with the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the air blower, the second regulating valve, the third regulating valve, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter.
Optionally, the first regulating valve is a manual air flow regulating valve, and the second regulating valve and the third regulating valve are electric air flow regulating valves.
Optionally, the control unit comprises a PLC, an upper computer and a blower controller; the output ends of the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are connected with the PLC through signal transmission lines, the PLC is connected with the upper computer, the upper computer is connected with the air blower controller, the second regulating valve and the third regulating valve through control transmission lines, and the air blower controller is connected with the air blower.
The invention also provides a dissolved oxygen control method for the sewage treatment system, which comprises the following steps of:
measuring the sewage flow by using a liquid flowmeter, and calculating the water lag time according to the sewage flowmeter within a set time;
respectively obtaining a second required aeration amount and a third required aeration amount of the second aeration tank and the third aeration tank in the set time period;
Acquiring the total required aeration quantity of the sewage treatment system after the set time length and the water quantity lag time length are passed;
each time the second and third desired aeration levels are obtained and the water amount lag time elapses, a second actual air supply amount in the second aeration tank and a third actual air supply amount in the third aeration tank are obtained;
and controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively.
Optionally, the formula for calculating the water lag time according to the sewage flow is:
wherein T1 is the water lag time, m is the volume coefficient, n is primary sedimentation Chi Geshu, p is the number of biological pools, V CC Is the volume of the primary sedimentation tank, V is the volume of the biological tank, q F For the average value of the sewage flow in the set time period, V INF Is the flow coefficient, q R For the external reflux quantity, q r Is the internal reflux quantity.
Optionally, the obtaining the total required aeration amount of the sewage treatment system after the set time period and the water amount lag time period includes:
Acquiring a first required aeration amount in the first aeration tank, wherein the first required aeration amount is a value of the first gas flow meter after the second required aeration amount and the third required aeration amount are acquired every time the water amount lag time is finished, and the first required aeration amount is G1;
the formula for calculating the second required aeration amount in the second aeration tank and the third required aeration amount in the third aeration tank is as follows:
wherein S is SF : concentration of water inlet substance S OF : concentration of dissolved oxygen in inlet water S O,sat : saturated dissolved oxygen concentration, S S : concentration of aeration tank substrate, S O : dissolved oxygen concentration in aeration tank S It is desirable to : setting the concentration of dissolved oxygen in an aeration tank, K OH : oxygen saturation coefficient, K S : substrate saturation coefficient, Y H : coefficient of yield, X H : heterotrophic bacteria concentration, X in aeration tank HF : concentration of heterotrophic bacteria in Water b H : heterotrophic bacteria decay factor, f P : inert component, q W : excess sludge discharge, a: maximum aeration air oxygen diffusion coefficient, b: attenuation coefficient, μ in Monod model H : maximum growth rate of heterotrophic bacteria; c is a correction coefficient;
when said S SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H Q when c is the parameter of the second aeration tank A For said second desired amount of aeration;
when said S SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H When c is the parameter of the third aeration tank, q A For said third desired aeration quantity;
taking the sum of the first required aeration amount, the second required aeration amount and the third required aeration amount as the total required aeration amount.
Optionally, the calculating the second required aeration amount in the second aeration tank and the calculating the third required aeration amount in the third aeration tank further include correcting the second required aeration amount and the third required aeration amount, obtaining a second required aeration amount correction value and a third required aeration amount correction value, and taking the sum of the first required aeration amount, the second required aeration amount correction value and the third required aeration amount correction value as the total required aeration amount.
Optionally, the controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount, respectively, includes:
acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
Setting a first threshold value of the first difference value and a second threshold value of the second difference value;
comparing the first difference value with the first threshold value, comparing the second difference value with the second threshold value, and keeping the opening degree of the second regulating valve unchanged when the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the first difference value is not in the range of the first threshold value, adjusting the opening degree of the second adjusting valve until the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the second difference value is within the range of the second threshold value, the opening degree of the third regulating valve is unchanged;
and when the absolute value of the second difference value is not in the range of the second threshold value, adjusting the opening degree of the third adjusting valve until the absolute value of the second difference value is in the range of the second threshold value.
Optionally, the method further comprises:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank by using the ammonia nitrogen monitor;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with the ammonia nitrogen content threshold value, and when the ammonia nitrogen content is not in the ammonia nitrogen content threshold value range, correcting the second required aeration amount and the third required aeration amount, and controlling the opening of the second regulating valve and the opening of the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
And when the ammonia nitrogen content is within the ammonia nitrogen content threshold range, opening degrees of the second regulating valve and the third regulating valve are not regulated.
Optionally, the method further comprises:
measuring a first dissolved oxygen amount and a second dissolved oxygen amount in the second aeration tank and the third aeration tank, respectively, using the first dissolved oxygen meter and the second dissolved oxygen meter;
setting a first dissolved oxygen standard value of the second aeration tank and a second dissolved oxygen standard value of the third aeration tank;
obtaining a third difference value between the first dissolved oxygen amount and the first dissolved oxygen amount standard value and a fourth difference value between the second dissolved oxygen amount and the second dissolved oxygen amount standard value;
setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference value and the fourth difference value with the third threshold value and the fourth threshold value respectively, correcting the second required aeration amount when the third difference value is not in the range of the third threshold value, and controlling the opening of the second regulating valve again according to the difference value between the second actual air supply amount and the second required aeration amount;
when the fourth difference value is not in the range of the fourth threshold value, correcting the third required aeration amount, and controlling the opening of the third regulating valve again according to the difference value between the third actual air supply amount and the third required aeration amount;
When the third difference value is within the range of the third threshold value, not adjusting the opening degree of the second adjusting valve;
and when the fourth difference value is within the range of the fourth threshold value, not adjusting the opening degree of the third adjusting valve.
The invention provides a dissolved oxygen control device and a dissolved oxygen control method for a sewage treatment system, which have the beneficial effects that:
1. the method utilizes the device to precisely control the dissolved oxygen in the aeration tank of the sewage treatment system at regular time, and can ensure the stable and efficient operation of the sewage treatment process;
2. according to the method, the required aeration quantity of each of the three aeration tanks can be accurately calculated through a formula, the second required aeration quantity and the third required aeration quantity can be corrected, the calculation accuracy is improved, and the control accuracy is further improved;
3. according to the method, according to the difference value between the actual air supply amount and the required aeration amount, the control of dissolved oxygen in an aeration tank is realized by adjusting the opening of an adjusting valve, the reliability of dissolved oxygen control is improved, the control method is mainly dependent on a liquid flowmeter and an ammonia nitrogen monitor with higher reliability, the degree of dependence on the dissolved oxygen instrument with lower reliability is lower, and the reliability of the control device and the control method is improved;
4. According to the method, the control of the dissolved oxygen in the aeration tank is realized by adjusting the opening of the regulating valve according to the ammonia nitrogen content in the secondary sedimentation tank and the dissolved oxygen amount measured by the dissolved oxygen meter in the aeration tank, so that the stability of the dissolved oxygen in the aeration tank is further ensured, and the control effect is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular descriptions of exemplary embodiments of the invention as illustrated in the accompanying drawings wherein like reference numbers generally represent like parts throughout the exemplary embodiments of the invention.
Fig. 1 shows a schematic configuration of a dissolved oxygen control apparatus for a sewage treatment system according to an embodiment of the present invention.
Fig. 2 shows a flow chart of a dissolved oxygen control method for a wastewater treatment system according to an embodiment of the present invention.
Reference numerals illustrate:
1. a non-aeration tank; 2. a first aeration tank; 3. a second aeration tank; 4. a third aeration tank; 5. a secondary sedimentation tank; 6. a liquid flow meter; 7. a first dissolved oxygen meter; 8. a second dissolved oxygen meter; 9. an ammonia nitrogen monitor; 10. a signal transmission line; 11. a PLC; 12. an upper computer; 13. a control transmission line; 14. a blower controller; 15. a blower; 16. a first gas flow meter; 17. a first regulating valve; 18. a second gas flow meter; 19. a second regulating valve; 20. a third gas flow meter; 21. and a third regulating valve.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the preferred embodiments of the present invention are described below, it should be understood that the present invention may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The invention provides a dissolved oxygen control device for a sewage treatment system, which comprises a non-aeration tank, a first aeration tank, a second aeration tank, a third aeration tank and a secondary sedimentation tank which are sequentially arranged from front to back, and is characterized in that the device comprises:
a liquid flowmeter arranged in the non-aeration tank;
the first dissolved oxygen meter and the second dissolved oxygen meter are respectively arranged in the second aeration tank and the third aeration tank;
the ammonia nitrogen monitor is arranged in the secondary sedimentation tank;
the air blower is connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline respectively, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
The first gas flowmeter, the second gas flowmeter and the third gas flowmeter are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the control unit is connected with the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the blower, the second regulating valve, the third regulating valve, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter.
Specifically, the liquid flowmeter is used for measuring the sewage flow of the sewage treatment system, the first dissolved oxygen meter and the second dissolved oxygen meter are respectively used for measuring the first dissolved oxygen amount and the second dissolved oxygen amount in the second aeration tank and the third aeration tank, the ammonia nitrogen monitor is used for measuring the ammonia nitrogen content of sewage in the secondary sedimentation tank, the blower can respectively supply air to the first aeration tank, the second aeration tank and the third aeration tank through the first pipeline, the second pipeline and the third pipeline, the first regulating valve, the second regulating valve and the third regulating valve respectively control the air supply flow in the first pipeline, the second pipeline and the third pipeline, and the first air flowmeter, the second air flowmeter and the third air flowmeter are respectively used for measuring the air supply flow in the first pipeline, the second pipeline and the third pipeline; the control unit can control the blower, the second regulating valve and the third regulating valve according to parameters measured by the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter by the following method, so as to control the dissolved oxygen of the sewage treatment system.
Optionally, the first regulating valve is a manual air flow regulating valve, and the second regulating valve and the third regulating valve are electric air flow regulating valves.
Specifically, the opening of the first regulating valve is regulated to the maximum during use.
Optionally, the opening degree adjustment range of the second adjusting valve and the third adjusting valve is 40% -90%.
Specifically, the opening adjustment ranges of the second adjusting valve and the third adjusting valve are set, normal and safe operation of each aeration tank is guaranteed, and a certain adjustable space is reserved.
In one example, the control unit includes a PLC, an upper computer, and a blower controller; the output ends of the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are connected with a PLC through signal transmission lines, the PLC is connected with an upper computer, the upper computer is connected with a blower controller, a second regulating valve and a third regulating valve through control transmission lines, and the blower controller is connected with a blower.
In other examples, the control unit may also communicate via the communication module to enable transmission of signals and transmission of control instructions.
Specifically, the air blower controller can correspondingly adjust the changes of the pressure of the pipeline and the back pressure of the air blower caused by the changes of the air demand of the three aeration tanks and the changes of the opening of the three regulating valves.
The invention also provides a dissolved oxygen control method for the sewage treatment system, which comprises the following steps of:
measuring the sewage flow by using a liquid flowmeter, and calculating the water lag time according to the sewage flowmeter within a set time;
respectively obtaining a second required aeration amount and a third required aeration amount of the second aeration tank and the third aeration tank in a set time period;
acquiring the total required aeration quantity of the sewage treatment system after a set time length and a water quantity lag time length;
each time the second required aeration amount and the third required aeration amount are obtained, and after the water lag time is elapsed, the second actual air supply amount in the second aeration tank and the third actual air supply amount in the third aeration tank are obtained;
and controlling the opening of the second regulating valve and the opening of the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively.
Specifically, the second and third gas flow meters can measure the gas supply flow in the second and third pipelines respectively, and each time the second and third pipelines finish acquiring the second required aeration amount and the third required aeration amount, the second actual gas supply amount and the third actual gas supply amount are acquired once after the water lag time is elapsed; the method uses the difference between the actual air supply amount and the required air supply amount to find the difference, and adjusts the opening of the second regulating valve and the third regulating valve according to the positive and negative and the size of the difference, thereby adjusting the air supply amount and the dissolved oxygen amount, not only improving the control accuracy and timeliness, but also enabling the control method to mainly depend on a liquid flowmeter and a gas flowmeter with higher reliability, and improving the reliability of the control device and the control method.
Furthermore, the set time length can be set according to the sewage flow, and the method adjusts the second regulating valve and the third regulating valve once after each set time length and after the water quantity lag time length, so as to realize the timing control of the dissolved oxygen; the total required aeration quantity is used as the basis for controlling the output power of the air blower by the air blower controller, which is beneficial to controlling the air blower, and reduces the energy consumption of the air blower on the premise of meeting the air supply requirement.
Optionally, the formula for calculating the water lag time according to the sewage flow meter is as follows:
wherein T1 is the water lag time, m is the volume coefficient, n is the primary sedimentation Chi Geshu, p is the number of biological pools, V CC Is the volume of the primary sedimentation tank, V is the volume of the biological tank, q F To set the average value of sewage flow in a period of time, V INF Is the flow coefficient, q R For the external reflux quantity, q r Is the internal reflux quantity.
Specifically, the parameters can be obtained from the existing sewage treatment system and the specification and actual treatment capacity parameters thereof.
Optionally, obtaining the total required aeration amount of the sewage treatment system after the set time period and the water amount lag time period comprises the following steps:
acquiring a first required aeration amount in a first aeration tank, wherein the first required aeration amount is a value of a first gas flow meter after the second required aeration amount and the third aeration amount are acquired every time and the water amount lag time is elapsed, and the first required aeration amount is G1;
The formula for calculating the second required aeration amount in the second aeration tank and the third required aeration amount in the third aeration tank is:
wherein S is SF : concentration of water inlet substance S OF : concentration of dissolved oxygen in inlet water S O,sat : saturated dissolved oxygen concentration, S S : concentration of aeration tank substrate, S O : dissolved oxygen concentration in aeration tank S It is desirable to : setting the concentration of dissolved oxygen in an aeration tank, K OH : oxygen saturation coefficient, K S : substrate saturation coefficient, Y H : coefficient of yield, X H : heterotrophic bacteria concentration, X in aeration tank HF : concentration of heterotrophic bacteria in Water b H : heterotrophic bacteria decay factor, f P : inert component, q W : excess sludge discharge, a: maximum aeration air oxygen diffusion coefficient, b: attenuation coefficient, μ in Monod model H : maximum growth rate of heterotrophic bacteria; c is a correction coefficient;
when S is SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H Q when c is the parameter of the second aeration tank A The aeration amount is the second required aeration amount;
when S is SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H When c is the parameter of the third aeration tank, q A To be third requiredAeration quantity;
taking the sum of the first required aeration amount, the second required aeration amount and the third required aeration amount as the total required aeration amount.
Specifically, the parameters can be obtained from the existing sewage treatment system and the specification and actual treatment capacity parameters thereof; the required aeration amounts of the second aeration tank and the third aeration tank can be calculated respectively by using the formula.
Optionally, calculating the second required aeration amount in the second aeration tank and calculating the third required aeration amount in the third aeration tank further includes correcting the second required aeration amount and the third required aeration amount, obtaining a second required aeration amount correction value and a third required aeration amount correction value, and taking the sum of the first aeration amount, the second required aeration amount correction value and the third required aeration amount correction value as the total required aeration amount.
Specifically, the correction method comprises the following steps:
the state variable is recorded as a state variable,control variable is q A Use->Representing the dynamic relation in the aeration amount calculation formula, the right end term in the above equation set can be obtained +.>The objective function in the optimization control is set as: />
Wherein T is a set duration, the objective function comprises two integral items, the first item measures the actual DO concentration from the expected value, the second item is the air supply flow, the objective function is minimized to ensure that DO concentration only fluctuates in the interval around the expected value, and the aeration quantity can be reduced, thereby achieving the purpose of energy saving, and alpha epsilon R < lambda+ > is a weight for adjusting the relative proportion of the first item and the second item in the objective function.
Optionally, controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount, respectively, includes:
Acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
setting a first threshold value of the first difference value and a second threshold value of the second difference value;
comparing the first difference value with a first threshold value, comparing the second difference value with a second threshold value, and keeping the opening degree of the second regulating valve unchanged when the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the first difference value is not in the range of the first threshold value, adjusting the opening of the second adjusting valve until the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the second difference value is in the range of the second threshold value, the opening degree of the third regulating valve is unchanged;
and when the absolute value of the second difference value is not in the range of the second threshold value, adjusting the opening degree of the third adjusting valve until the absolute value of the second difference value is in the range of the second threshold value.
Specifically, defining a second required aeration amount as G2, defining a first difference as Δg2, Δg2=a second actual air supply amount-G2, defining a third required aeration amount as G3, defining a second difference as Δg3, Δg3=a third actual air supply amount-G3, defining a first threshold as a section from-n% G2 to n% G2, if |Δg2| < n% G2, keeping the opening of the second regulating valve unchanged, and similarly, if |Δg3| < n% G3, keeping the opening of the third regulating valve unchanged; if delta G2 is more than n percent G2, starting to reduce the opening of the second regulating valve, and adjusting the air supply amount of the second aeration tank in real time to enable delta G2 to be less than n percent G2; if delta G2< -n% G2, starting to increase the opening of the second regulating valve, and adjusting the air supply amount of the second aeration tank in real time to enable delta G2< n% G2; the dissolved oxygen control step for the third aeration tank is the same as the dissolved oxygen control step for the second aeration tank described above.
Further, the control principle of the first, second and third regulating valves is that the second regulating valve is regulated firstly, the third regulating valve is regulated after the opening of the second regulating valve meets the requirement, and the opening of the rest regulating valves is kept unchanged no matter which regulating valve is regulated; the opening degree of the first regulating valve is kept to be the maximum; the second regulating valve and the third regulating valve ensure that the opening of the second regulating valve and the third regulating valve is 40% -90% in the regulating process.
Optionally, the method further comprises:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank by using an ammonia nitrogen monitor;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with an ammonia nitrogen content threshold value, and when the ammonia nitrogen content is not in the ammonia nitrogen content threshold value range, correcting the second required aeration amount and the third required aeration amount, and controlling the opening of the second regulating valve and the opening of the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
and when the ammonia nitrogen content is within the ammonia nitrogen content threshold range, opening degrees of the second regulating valve and the third regulating valve are not regulated.
Specifically, the method compares the ammonia nitrogen content with an ammonia nitrogen content threshold value to realize DONH 4 The feedback control, the control logic is as follows: when the ammonia nitrogen content is not in the ammonia nitrogen content threshold value range, correcting the second required aeration amount and the third required aeration amount to enable the first difference value and the second difference value to be changed, further repeatedly comparing the first difference value with the first threshold value, the second difference value with the second threshold value, and then adjusting the opening of the second regulating valve and the opening of the third regulating valve.
In one example, the above step is DONH 4 And (3) feedback control: firstly, checking the NH of effluent displayed by an ammonia nitrogen monitor 4 Value of NH 4 >n 1 mg/L, increasing G2 and G3 by ΔG, respectively, when NH 4 <n 2 mg/L, G2 and G3 are respectively reduced by delta G; otherwise, the DO feedback step described below is entered directly.
Optionally, increasing the opening of the second regulating valve and the third regulating valve when the ammonia nitrogen content is smaller than the minimum value of the ammonia nitrogen content threshold value;
when the oxygen content of the ammonia nitrogen is larger than the maximum value of the threshold value of the ammonia nitrogen content, reducing the opening of the second regulating valve and the opening of the third regulating valve;
and when the ammonia nitrogen content is within the ammonia nitrogen content threshold range, opening degrees of the second regulating valve and the third regulating valve are not regulated.
Specifically, the control of the opening degrees of the second regulating valve and the third regulating valve can be realized according to the logic, so that the control of the dissolved oxygen is realized.
Optionally, the method further comprises:
measuring a first dissolved oxygen amount and a second dissolved oxygen amount in the second aeration tank and the third aeration tank respectively by using a first dissolved oxygen meter and a second dissolved oxygen meter;
setting a first dissolved oxygen standard value of the second aeration tank and a second dissolved oxygen standard value of the third aeration tank;
obtaining a third difference value between the first dissolved oxygen and a first dissolved oxygen standard value and a fourth difference value between the second dissolved oxygen and a second dissolved oxygen standard value;
Setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference value with a third threshold value and the fourth difference value with the fourth threshold value respectively, correcting the second required aeration amount when the third difference value is not in the range of the third threshold value, and controlling the opening of the second regulating valve again according to the difference value between the second actual air supply amount and the second required aeration amount;
when the fourth difference value is not in the range of the fourth threshold value, correcting the third required aeration amount, and controlling the opening of the third regulating valve again according to the difference value between the third actual air supply amount and the third required aeration amount;
when the third difference value is in the range of the third threshold value, the opening degree of the second regulating valve is not regulated;
when the fourth difference is within the range of the fourth threshold value, the opening degree of the third regulating valve is not regulated.
Specifically, the method compares the third difference value and the fourth difference value with a third threshold value and a fourth threshold value respectively, realizes DO feedback control, and the control logic is as follows: when the third difference value is not in the range of the third threshold value, correcting the second required aeration quantity to change the first difference value, further repeatedly comparing the first difference value with the first threshold value, and then adjusting the opening of the second regulating valve; when the fourth difference value is not in the range of the fourth threshold value, the third required aeration amount is corrected, so that the second difference value is changed, the second difference value and the second threshold value are compared repeatedly, and the opening of the third regulating valve is regulated.
In one example, the above step is DO feed-back control: firstly, the first dissolved oxygen amount and the second dissolved oxygen amount measured by a first dissolved oxygen meter are respectively compared with a first dissolved oxygen amount standard value and a second dissolved oxygen amount standard value which are set in a controller, a third difference value is defined as delta DO2, delta DO2 = first dissolved oxygen amount-first dissolved oxygen amount standard value, when delta DO2 is>d 1 At mg/L, G2 is reduced by an amount equal to ΔDO2<-d 1 mg/L, increasing G2 by an amount that would otherwise maintain G2 unchanged; then, a third regulating valve is regulated by the same method, and G3 is regulated; and finally, repeating the step of comparing the first difference value and the second difference value with the first threshold value and the second threshold value respectively, so that the steps are repeated, the dissolved oxygen of the sewage treatment system is controlled in real time, and the sewage treatment effect is improved.
Optionally, when the absolute value of the third difference value is within the range of the third threshold value, the opening degree of the second regulating valve is unchanged, and the second required aeration amount is kept unchanged;
when the absolute value of the third difference value is not in the range of the third threshold value, the opening degree of the second regulating valve is regulated, so that the second required aeration amount is increased or reduced until the absolute value of the third difference value is in the range of the third threshold value;
when the absolute value of the fourth difference value is in the range of the fourth threshold value, the opening of the third regulating valve is unchanged, and the third required aeration amount is kept unchanged;
And when the absolute value of the fourth difference value is not in the range of the fourth threshold value, adjusting the opening degree of the third regulating valve, so as to increase or decrease the third required aeration amount until the absolute value of the fourth difference value is in the range of the fourth threshold value.
Specifically, the control of the opening degrees of the second regulating valve and the third regulating valve can be realized according to the logic, so that the control of the dissolved oxygen is realized.
Examples
As shown in fig. 1 and 2, the present invention provides a dissolved oxygen control apparatus for a sewage treatment system including a non-aeration tank 1, a first aeration tank 2, a second aeration tank 3, a third aeration tank 4, and a secondary sedimentation tank 5, which are sequentially disposed from front to rear, characterized in that the apparatus comprises:
a liquid flowmeter 6 disposed in the non-aeration tank 1;
the first dissolved oxygen meter 7 and the second dissolved oxygen meter 8 are respectively arranged in the second aeration tank 3 and the third aeration tank 4;
the ammonia nitrogen monitor 9 is arranged in the secondary sedimentation tank 5;
the air blower 15 is connected with the first aeration tank 2, the second aeration tank 3 and the third aeration tank 4 through a first pipeline, a second pipeline and a third pipeline respectively, and a first regulating valve 17, a second regulating valve 19 and a third regulating valve 21 are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
A first gas flow meter 16, a second gas flow meter 18, and a third gas flow meter 20 disposed on the first pipeline, the second pipeline, and the third pipeline, respectively;
the control unit is connected with the first dissolved oxygen meter 7, the second dissolved oxygen meter 8, the ammonia nitrogen monitor 9, the blower 15, the second regulating valve 19, the third regulating valve 21, the first gas flow meter 16, the second gas flow meter 18 and the third gas flow meter 20.
In the present embodiment, the first regulating valve 17 is a manual air amount regulating valve, and the second regulating valve 19 and the third regulating valve 21 are electric air amount regulating valves.
In the present embodiment, the control unit includes a PLC11, an upper computer 12, and a blower controller 14; the output ends of the first dissolved oxygen meter 7, the second dissolved oxygen meter 8, the ammonia nitrogen monitor 9, the first gas flow meter 16, the second gas flow meter 18 and the third gas flow meter 20 are connected with the PLC11 through the signal transmission line 10, the PLC11 is connected with the upper computer 12, the upper computer 12 is connected with the blower controller 14, the second regulating valve 19 and the third regulating valve 21 through the control transmission line 13, and the blower controller 14 is connected with the blower 15.
The invention also provides a dissolved oxygen control method for the sewage treatment system, which comprises the following steps of:
Measuring the sewage flow by using a liquid flowmeter 6, and calculating the water lag time according to the sewage flowmeter within a set time;
respectively obtaining a second required aeration amount and a third required aeration amount of the second aeration tank 3 and the third aeration tank 4 in a set duration;
acquiring the total required aeration quantity of the sewage treatment system after a set time length and a water quantity lag time length;
each time the second required aeration amount and the third required aeration amount are obtained and the second actual air supply amount in the second aeration tank 3 and the third actual air supply amount in the third aeration tank 4 are obtained after the water lag time period;
the opening degrees of the second regulating valve 19 and the third regulating valve 21 are controlled in accordance with the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount, respectively.
In this embodiment, the formula for calculating the water lag time according to the sewage flow meter is:
wherein T1 is the water lag time, m is the volume coefficient, n is the primary sedimentation Chi Geshu, p is the number of biological pools, V CC Is the volume of the primary sedimentation tank, V is the volume of the biological tank, q F To set the average value of sewage flow in a period of time, V INF Is the flow coefficient, q R For the external reflux quantity, q r Is the internal reflux quantity.
In the present embodiment of the present invention, in the present embodiment,
The method for obtaining the total required aeration quantity of the sewage treatment system after the set time length and the water quantity lag time length comprises the following steps:
acquiring a first required aeration amount in a first aeration tank 3, wherein the first required aeration amount is a value of a first gas flow meter after the second required aeration amount and the third aeration amount are acquired every time and the water amount lag time is elapsed, and the first required aeration amount is G1;
the formula for calculating the second required aeration amount in the second aeration tank 3 and the third required aeration amount in the third aeration tank 4 is:
wherein S is SF : concentration of water inlet substance S OF : concentration of dissolved oxygen in inlet water S O,sat : saturated dissolved oxygen concentration, S S : concentration of aeration tank substrate, S O : dissolved oxygen concentration in aeration tank S It is desirable to : setting the concentration of dissolved oxygen in an aeration tank, K OH : oxygen saturation coefficient, K S : substrate saturation coefficient, Y H : coefficient of yield, X H : heterotrophic bacteria concentration, X in aeration tank HF : concentration of heterotrophic bacteria in Water b H : heterotrophic bacteria decay factor, f P : inert component, q W : excess sludge discharge, a: maximum aeration air oxygen diffusion coefficient, b: attenuation coefficient, μ in Monod model H : maximum growth rate of heterotrophic bacteria; c is a correction coefficient;
when S is SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H Q when c is a parameter of the second aeration tank 3 A The aeration amount is the second required aeration amount;
when S is SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H When c is a parameter of the third aeration tank 4, q A The aeration amount is the third required aeration amount;
taking the sum of the first required aeration amount, the second required aeration amount and the third required aeration amount as the total required aeration amount.
In this embodiment, calculating the second required aeration amount in the second aeration tank 3 and calculating the third required aeration amount in the third aeration tank 4 further includes correcting the second required aeration amount and the third required aeration amount, obtaining the second required aeration amount correction value and the third required aeration amount correction value, and taking the sum of the first aeration amount, the second required aeration amount correction value and the third required aeration amount correction value as the total required aeration amount.
In the present embodiment, controlling the opening degrees of the second regulating valve 19 and the third regulating valve 21 according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount, respectively, includes:
acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
setting a first threshold value of the first difference value and a second threshold value of the second difference value;
comparing the first difference value with a first threshold value, comparing the second difference value with a second threshold value, and when the absolute value of the first difference value is within the range of the first threshold value, keeping the opening degree of the second regulating valve 19 unchanged;
When the absolute value of the first difference is not within the range of the first threshold value, the opening degree of the second regulating valve 19 is regulated until the absolute value of the first difference is within the range of the first threshold value;
when the absolute value of the second difference is within the range of the second threshold value, the opening degree of the third regulating valve 21 is unchanged;
when the absolute value of the second difference is not within the range of the second threshold value, the opening degree of the third regulating valve 21 is regulated until the absolute value of the second difference is within the range of the second threshold value.
In this embodiment, the method further includes:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank 5 by using an ammonia nitrogen monitor 9;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with an ammonia nitrogen content threshold value, and when the ammonia nitrogen content is not in the ammonia nitrogen content threshold value range, correcting the second required aeration amount and the third required aeration amount, and controlling the opening of the second regulating valve 19 and the third regulating valve 21 according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
when the ammonia nitrogen content is within the ammonia nitrogen content threshold range, the opening degrees of the second regulating valve 19 and the third regulating valve 21 are not regulated.
In this embodiment, the method further includes:
measuring the first dissolved oxygen amount and the second dissolved oxygen amount in the second aeration tank 3 and the third aeration tank 4 by using the first dissolved oxygen meter 7 and the second dissolved oxygen meter 8, respectively;
Setting a first dissolved oxygen standard value of the second aeration tank 3 and a second dissolved oxygen standard value of the third aeration tank 4;
obtaining a third difference value between the first dissolved oxygen and a first dissolved oxygen standard value and a fourth difference value between the second dissolved oxygen and a second dissolved oxygen standard value;
setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference value and the fourth difference value with a third threshold value and a fourth threshold value respectively, correcting the second required aeration amount when the third difference value is not in the range of the third threshold value, and controlling the opening of the second regulating valve 19 again according to the difference value between the second actual air supply amount and the second required aeration amount;
when the fourth difference value is not within the range of the fourth threshold value, correcting the third required aeration amount, and controlling the opening degree of the third regulating valve 21 again according to the difference value between the third actual air supply amount and the third required aeration amount;
when the third difference is within the range of the third threshold value, the opening degree of the second regulating valve 19 is not regulated;
when the fourth difference is within the range of the fourth threshold value, the opening degree of the third regulating valve 21 is not regulated.
In summary, when the dissolved oxygen control device and method for a sewage treatment system provided by the invention are used, the opening adjustment range of the second adjusting valve 19 and the third adjusting valve 21 is set to be 40% -90%, the change threshold value of the first dissolved oxygen meter 7 is +/-0.5 mg/L, the change threshold value of the second dissolved oxygen meter 8 is +/-0.12 mg/L, and the change threshold value of the second gas flowmeter 18 is +/-300 m in the controller 3 And/s, the third gas flowmeter 20 has a change threshold of + -200 m 3 /s。
The sewage flow is collected every 5 minutes by using the liquid flowmeter 6, and the average value of the sewage flow within 1 hour of a set time length is taken as q F Calculating a required water amount lag time T1 according to a formula, and calculating a second required aeration amount C1 and a third required aeration amount C2 of the second aeration tank 3 and the third aeration tank 4 within 1 hour respectively by using the formula; and then C1 and C2 are corrected, a second required aeration quantity correction value G2 and a third required aeration quantity correction value G3 are obtained after correction, the value of the first gas flowmeter after the set time length and the water quantity lag time length T1 is taken as a first required aeration quantity G1, and the total required aeration quantity G=G1+G2+G3.
The control unit transmits the total required aeration amount obtained according to calculation to the blower controller 14, and the blower controller 14 controls the blower 15 to operate; after the water lag time T1 is acquired, a first difference Δg2=a second actual air supply amount-G2, a second difference Δg3=a third actual air supply amount-G3, a first threshold is a section from-3% G2 to 3% G2, a second threshold is ±3% G3, if |Δg2| <3% G2, the opening of the second regulating valve 19 is kept unchanged, and similarly, if |Δg3| <3% G3, the opening of the third regulating valve 21 is kept unchanged; if Δg2>3% G2, starting to reduce the opening of the second regulating valve 19, and adjusting the air supply amount of the second aeration tank 3 in real time so that |Δg2| <3% G2; if delta G2< -3% G2, starting to increase the opening of the second regulating valve 19, and adjusting the air supply amount of the second aeration tank 3 in real time so that delta G2< 3% G2; the method for regulating and controlling the dissolved oxygen of the third aeration tank 4 is the same as that of the second aeration tank 3; after the control step is completed, the following ammonia nitrogen content feedback control link is entered.
And (3) ammonia nitrogen content feedback control: firstly, the ammonia nitrogen monitor 9 is used for measuring the NH of the effluent 4 Content of NH 4 Content of>At 1mg/L, G2 and G3 are respectively increased by 800m 3 /h, when NH 4 Content of<At 0.1mg/L, G2 and G3 are reduced by 800m respectively 3 /h; and then the opening degrees of the second regulating valve 19 and the third regulating valve 21 are regulated again according to the comparison of the first difference value and the first threshold value and the comparison of the second difference value and the second threshold value; otherwise, directly entering the following dissolved oxygen feedback control link.
Dissolved oxygen feed-back control: firstly, the opening of the second regulating valve 19 is controlled, a third difference value in the second aeration tank 3 is defined as delta DO2, delta DO2 = first dissolved oxygen amount-first dissolved oxygen amount standard value, a third threshold value is defined as a section from-1 mg/L to 1mg/L, and when delta DO2 is defined as>At 1mg/L, G2 was reduced by 500m 3 And/h, re-adjusting the opening of the second regulating valve 19 according to the comparison of the third difference value and the third threshold value; when DeltaDO 2<At-1 mg/L, G2 is increased by 500m 3 And/h, re-adjusting the opening of the second regulating valve 19 according to the comparison of the third difference value and the third threshold value; otherwise, maintaining G2 unchanged; then the opening of the third regulating valve 21 is controlled, the fourth difference in the third aeration tank 4 is defined as delta DO3, delta DO3 = second dissolved oxygen amount-second dissolved oxygen amount standard value, the fourth threshold is defined as a section from-1 mg/L to 1mg/L, and when delta DO3 is >At 1mg/L, G3 was reduced by 500m 3 And/h, re-adjusting the opening of the third regulating valve 21 according to the comparison of the fourth difference value and the fourth threshold value; when DeltaDO 3<At-1 mg/L, G3 was increased by 500m 3 And/h, re-adjusting the opening of the third regulating valve 21 according to the comparison of the fourth difference value and the fourth threshold value; otherwise, G3 is maintained unchanged.
In this embodiment, the control principle of the regulating valve is: the opening of the first regulating valve 17 is adjusted to the maximum; the second regulating valve 19 is regulated first, and the third regulating valve 21 is regulated after meeting the requirement, and the opening degree of the rest regulating valves is kept unchanged no matter which electric regulating valve is operated.
In addition, the blower controller 14 can make corresponding adjustments to the changes in the gas line pressure and the blower 15 back pressure caused by the changes in the air demand of the three aeration tanks and the changes in the opening of the three regulating valves.
After the trial of the embodiment, the dissolved oxygen control effect is obvious, the aeration energy consumption is reduced to some extent, and the water quality stability and standard reaching rate of the effluent are improved to some extent.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described.
Claims (7)
1. A dissolved oxygen control method for a sewage treatment system, using a dissolved oxygen control apparatus for a sewage treatment system including a non-aeration tank, a first aeration tank, a second aeration tank, a third aeration tank, and a secondary sedimentation tank, which are sequentially disposed from front to back, characterized in that the apparatus comprises:
a liquid flowmeter arranged in the non-aeration tank;
the first dissolved oxygen meter and the second dissolved oxygen meter are respectively arranged in the second aeration tank and the third aeration tank;
the ammonia nitrogen monitor is arranged in the secondary sedimentation tank;
the air blower is respectively connected with the first aeration tank, the second aeration tank and the third aeration tank through a first pipeline, a second pipeline and a third pipeline, and a first regulating valve, a second regulating valve and a third regulating valve are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are respectively arranged on the first pipeline, the second pipeline and the third pipeline;
the control unit is connected with the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the blower, the second regulating valve, the third regulating valve, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter;
The method comprises the following steps:
measuring the sewage flow by using a liquid flowmeter, and calculating the water lag time according to the sewage flowmeter within a set time;
respectively obtaining a second required aeration amount and a third required aeration amount of the second aeration tank and the third aeration tank in the set time period;
acquiring the total required aeration quantity of the sewage treatment system after the set time length and the water quantity lag time length are passed;
each time the second and third desired aeration levels are obtained and the water amount lag time elapses, a second actual air supply amount in the second aeration tank and a third actual air supply amount in the third aeration tank are obtained;
controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
the formula for calculating the water lag time according to the sewage flow is as follows:
wherein T1 is the water lag time, m is the volume coefficient, n is primary sedimentation Chi Geshu, p is the number of biological pools, V CC Is the volume of the primary sedimentation tank, V is the volume of the biological tank, q F For the average value of the sewage flow in the set time period, V INF Is the flow coefficient, q R For the external reflux quantity, q r Is the internal reflux quantity;
the step of obtaining the total required aeration amount of the sewage treatment system after the set time period and the water quantity lag time period comprises the following steps:
acquiring a first required aeration amount in the first aeration tank, wherein the first required aeration amount is a value of the first gas flow meter after the second required aeration amount and the third required aeration amount are acquired every time the water amount lag time is finished, and the first required aeration amount is G1;
the formula for calculating the second required aeration amount in the second aeration tank and the third required aeration amount in the third aeration tank is as follows:
wherein S is SF S is the concentration of water inlet OF For the concentration of dissolved oxygen in the inlet water S O,sat Is saturated with dissolved oxygen concentration S S Is the concentration of the substrate of the aeration tank, S O For the dissolved oxygen concentration of the aeration tank, S It is desirable to To set the dissolved oxygen concentration of the aeration tank, K OH Is the oxygen saturation coefficient, K S For the saturation coefficient of the substrate, Y H As a yield coefficient, X H X is the concentration of heterotrophic bacteria in the aeration tank HF B for heterotrophic bacteria concentration in the feed water H Is the decay coefficient of heterotrophic bacteria, f P As inert component, q W For the residual sludge discharge, a is the air-space oxygen diffusion coefficient with the maximum aeration quantity, b is the attenuation coefficient in the Monod model, mu H Maximum growth rate for heterotrophic bacteria; c is a correction coefficient;
when said S SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H Q when c is the parameter of the second aeration tank A For said second desired amount of aeration;
when said S SF 、S OF 、S O,sat 、S S 、S O 、S It is desirable to 、K OH 、K S 、Y H 、X H 、X HF 、b H 、f P 、q W 、a、b、μ H When c is the parameter of the third aeration tank, q A For said third desired aeration quantity;
taking the sum of the first required aeration amount, the second required aeration amount and the third required aeration amount as the total required aeration amount.
2. The dissolved oxygen control method for a sewage treatment system according to claim 1, wherein the first regulating valve is a manual air quantity regulating valve, and the second regulating valve and the third regulating valve are electric air quantity regulating valves.
3. The dissolved oxygen control method for a sewage treatment system according to claim 1, wherein the control unit includes a PLC, an upper computer, and a blower controller; the output ends of the first dissolved oxygen meter, the second dissolved oxygen meter, the ammonia nitrogen monitor, the first gas flowmeter, the second gas flowmeter and the third gas flowmeter are connected with the PLC through signal transmission lines, the PLC is connected with the upper computer, the upper computer is connected with the air blower controller, the second regulating valve and the third regulating valve through control transmission lines, and the air blower controller is connected with the air blower.
4. The dissolved oxygen control method for a sewage treatment system according to claim 1, wherein the calculating the second required aeration amount in the second aeration tank and the calculating the third required aeration amount in the third aeration tank further includes correcting the second required aeration amount and the third required aeration amount, obtaining a second required aeration amount correction value and a third required aeration amount correction value, and taking a sum of the first required aeration amount, the second required aeration amount correction value, and the third required aeration amount correction value as the total required aeration amount.
5. The dissolved oxygen control method for a sewage treatment system according to claim 1, wherein the controlling the opening degrees of the second regulating valve and the third regulating valve according to the difference between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount, respectively, comprises:
acquiring a first difference value between the second actual air supply amount and the second required aeration amount and a second difference value between the third actual air supply amount and the third required aeration amount;
setting a first threshold value of the first difference value and a second threshold value of the second difference value;
Comparing the first difference value with the first threshold value, comparing the second difference value with the second threshold value, and keeping the opening degree of the second regulating valve unchanged when the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the first difference value is not in the range of the first threshold value, adjusting the opening degree of the second adjusting valve until the absolute value of the first difference value is in the range of the first threshold value;
when the absolute value of the second difference value is within the range of the second threshold value, the opening degree of the third regulating valve is unchanged;
and when the absolute value of the second difference value is not in the range of the second threshold value, adjusting the opening degree of the third adjusting valve until the absolute value of the second difference value is in the range of the second threshold value.
6. The dissolved oxygen control method for a sewage treatment system according to claim 1, characterized in that the method further comprises:
measuring the ammonia nitrogen content of the sewage in the secondary sedimentation tank by using the ammonia nitrogen monitor;
setting an ammonia nitrogen content threshold;
comparing the ammonia nitrogen content with the ammonia nitrogen content threshold value, and when the ammonia nitrogen content is not in the ammonia nitrogen content threshold value range, correcting the second required aeration amount and the third required aeration amount, and controlling the opening of the second regulating valve and the opening of the third regulating valve according to the difference value between the second actual air supply amount and the third actual air supply amount and the second required aeration amount and the third required aeration amount respectively;
And when the ammonia nitrogen content is within the ammonia nitrogen content threshold range, opening degrees of the second regulating valve and the third regulating valve are not regulated.
7. The dissolved oxygen control method for a sewage treatment system according to claim 1, characterized in that the method further comprises:
measuring a first dissolved oxygen amount and a second dissolved oxygen amount in the second aeration tank and the third aeration tank, respectively, using the first dissolved oxygen meter and the second dissolved oxygen meter;
setting a first dissolved oxygen standard value of the second aeration tank and a second dissolved oxygen standard value of the third aeration tank;
obtaining a third difference value between the first dissolved oxygen amount and the first dissolved oxygen amount standard value and a fourth difference value between the second dissolved oxygen amount and the second dissolved oxygen amount standard value;
setting a third threshold value of the third difference value and a fourth threshold value of the fourth difference value;
comparing the third difference value and the fourth difference value with the third threshold value and the fourth threshold value respectively, correcting the second required aeration amount when the third difference value is not in the range of the third threshold value, and controlling the opening of the second regulating valve again according to the difference value between the second actual air supply amount and the second required aeration amount;
When the fourth difference value is not in the range of the fourth threshold value, correcting the third required aeration amount, and controlling the opening of the third regulating valve again according to the difference value between the third actual air supply amount and the third required aeration amount;
when the third difference value is within the range of the third threshold value, not adjusting the opening degree of the second adjusting valve;
and when the fourth difference value is within the range of the fourth threshold value, not adjusting the opening degree of the third adjusting valve.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110326663.2A CN113149242B (en) | 2021-03-26 | 2021-03-26 | Dissolved oxygen control device and method for sewage treatment system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
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