CN107986428B - Sewage treatment accurate aeration method - Google Patents
Sewage treatment accurate aeration method Download PDFInfo
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- CN107986428B CN107986428B CN201711351017.1A CN201711351017A CN107986428B CN 107986428 B CN107986428 B CN 107986428B CN 201711351017 A CN201711351017 A CN 201711351017A CN 107986428 B CN107986428 B CN 107986428B
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- 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
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- 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 discloses an accurate aeration method for sewage treatment, which adjusts aeration quantity of each biological pond by adjusting opening of a butterfly valve and pressure of an air main pipe according to the change of concentration of on-line dissolved oxygen, solves the problem of reaction hysteresis of dissolved oxygen, avoids frequent adjustment of the butterfly valve, ensures relatively stable system pressure, achieves an accurate control effect, prolongs service life of equipment and finally achieves the aim of saving energy.
Description
Technical Field
The invention relates to the technical field of sewage treatment, in particular to an accurate aeration method for sewage treatment.
Background
The biological treatment of waste water is to decompose, absorb or adsorb pollutant to purify water quality through the metabolism of microbe, and has low cost, high efficiency and very low secondary pollution compared with physical and chemical methods. In order to meet the requirements of treating wastewater with different sources and different properties, various types of biological treatment processes and reactors such as anaerobic-aerobic activated sludge process, oxidation ditch method, SBR, AB method, biological contact oxidation method, BAF and the like have been developed. In these various types of processes, an aerobic treatment stage is typically included to accomplish the oxidation of the organic material and the removal of ammonia nitrogen. In order to provide an aerobic environment for microorganisms, blast aeration is currently used in a large number. To some extent, the control of aeration determines the treatment effect of the whole system on wastewater and the energy consumption level of a sewage treatment plant. Because the small aeration rate will inhibit the nitrification reaction in the system and in addition cause the proliferation of filamentous bacteria in the biological pond, resulting in sludge bulking: when the aeration amount is large, the aeration electricity consumption is wasted, and meanwhile, the sludge flocs are broken by strong air stirring, so that the water quality of the effluent is influenced. In addition, if the treatment process has the reflux of the nitrifying liquid, the refluxed nitrifying liquid can also bring oxygen into the anoxic zone, thereby affecting the denitrification effect. As the conditions of the water quality, the water temperature and the like of the influent water of the sewage plant have larger fluctuation, the aeration quantity is required to be timely adjusted in the aeration process so as to cope with the change.
In order to realize on-demand air supply and reduce aeration energy consumption, a proposal for precisely controlling the aeration quantity is proposed. The accurate aeration control is to integrate the on-line instrument, the valve and the blower into an intelligent control system, and to achieve the purpose of stabilizing the effluent quality of the sewage plant and saving energy by dynamically optimizing and adjusting the air supply quantity and supplying air as required as possible. Along with the improvement of the performance of on-line monitoring meters and related technical equipment of sewage treatment plants, the precise aeration control has become a reality from the idea.
At present, the mature precise aeration control technology at home and abroad can be divided into two types: a ' feedforward + feedback + biological processing module ' and a ' feedback regulation + superior hardware system.
The feed-forward + feedback + biological treatment module is based on an international water cooperation activated sludge model, predicts the aeration amount required by the biological pond according to historical operation data of the sewage plant and the change of water quality and water quantity detected by an on-line instrument, and adjusts air flow distribution and air quantity of an air blower by combining indexes such as actual dissolved oxygen, water temperature, MLSS and water pressure in the biological pond. The control mode is perfect, more indexes are required to be acquired, the performance stability of the instrument is high, and the air supply amount required by the biological pool is difficult to accurately predict by the biological module. Representative control systems for this model are the biological process intelligent control system (BIOS+BACS) of American Biochemical technology company (BioChcmTechnology lnc) and the AVS precise aeration flow control system of Shanghai sea haran System control technology Limited liability company. The accurate aeration system of the feedforward + feedback + biological treatment module can calculate the aeration quantity, but because the actual gas demand of the biological pool is related to various factors such as the efficiency of an aeration head, the length of an aeration pipeline, the flow rate of the biological pool and the mixing state, the gas demand calculation is often greatly different from the actual gas demand. However, to meet the tank air demand, the actual air manifold pressure will be maintained in a high range. The air supply is increased when the dissolved oxygen is reduced, and the valve opening is reduced when the dissolved oxygen is increased, so that the pressure is always maintained at a high level, and the energy consumption of the blower is greatly wasted when all the valves are depressed.
The control mode omits a feedforward and biological processing module, and solves the problems of excessive dependence on an on-line instrument and accuracy of a biological module. However, the system needs higher control capability to the valve and the blower, namely, the system can adjust the opening of the valve and the air quantity of the blower in a shorter time to meet the purposes of air supply quantity and energy saving required by the biological pond after water quality changes. A representative control system for this control mode is the VACOMASS control system of Bingder, germany (BINDER ENGINEERING).
In addition, the requirements of the two technologies on the on-line instrument (such as a water inlet flowmeter, an air flowmeter, a water inlet on-line ammonia nitrogen and COD monitoring instrument) and the biological module and the blower control hardware equipment are extremely high, so that the initial investment of a control system is high in price, the later maintenance workload is large, the cost is high, and if equipment hardware, a communication network and the on-line instrument are in failure, the system is in a semi-paralysis state.
Disclosure of Invention
The invention aims to provide a method capable of accurately controlling aeration of a biological pond.
In order to solve the technical problems, the invention adopts the following technical scheme:
a sewage treatment accurate aeration method is designed, which comprises the following steps:
(1) Introducing sewage to be treated into more than two biological tanks, wherein the biological tanks are provided with an aeration system in a matching way, the aeration system comprises a controller, a blower unit and aeration pipelines respectively arranged in the biological tanks, the aeration pipelines in each biological tank are communicated with an external air main pipe through a shunt pipe, butterfly valves are respectively arranged on the shunt pipes corresponding to each biological tank, a pressure gauge is arranged on the air main pipe, the blower unit is correspondingly connected with the air main pipe, and online dissolved oxygen measuring instruments are respectively arranged in the biological tanks; the butterfly valve, the blower unit, the pressure gauge and the online dissolved oxygen meter are respectively and correspondingly electrically connected with the controller;
(2) The dissolved oxygen concentration DO in each biological pool is measured by an online dissolved oxygen meter, and the average value A of the change rate of the dissolved oxygen concentration in the previous minute every 20 seconds is calculated by a controller, so that the change interval of the dissolved oxygen concentration DO is set: minimum value MIN < lower limit value L < upper limit value H < maximum value MAX;
(3) The current opening of each biological pond corresponding to the butterfly valve is obtained, and the butterfly valve adjusting amplitude and the time interval are obtained according to the opening interval of the butterfly valve shown in the following table 1:
(4) The opening degree of the butterfly valve is adjusted according to the following conditions:
(1) when DO is smaller than MIN, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0.03, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(2) when MIN is less than or equal to DO and less than L, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(3) when L is less than or equal to DO is less than or equal to H, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than 0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1; if A is less than-0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1; if A is more than or equal to-0.03 and less than or equal to 0.03, the opening of the butterfly valve of the biological pool is kept unchanged;
(4) when H is less than DO and less than or equal to MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is more than 0, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjusting amplitude shown in the table 1;
(5) when DO is more than MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to-0.03, the butterfly valve of the biological pool is kept unchanged in opening degree; if A > -0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1;
(5) Setting an air main pressure target value according to the aeration amount required by each biological pond, comparing the actual air main pressure value detected by a pressure gauge with the target value, and adjusting the air outlet amount of a blower unit by controlling the opening amount of the blowers and the opening degree of the guide vanes of the blowers when the actual air main pressure value and the target value are inconsistent, so as to adjust the air main pressure to the target value;
(6) After aeration is completed, the sewage treatment process is carried out in the next step.
Preferably, the method for adjusting the air manifold pressure target value in the step (5) comprises the following steps:
a. firstly, setting the auxiliary limit value of the butterfly valve opening of each biological pool as F0-F1, and when the butterfly valve opening reaches F0 and still needs to be adjusted downwards, namely the biological pool is in a descending request state; when the opening of the butterfly valve reaches F1 and still needs to be adjusted upwards, namely the biological pool is in a lifting request state;
b. acquiring a request state of a biological pool every ten minutes, and when at least two biological pools are in a rising request state, adjusting the pressure target value of the air main pipe by an amplitude P0; when at least two biological pools are in a descending request state, the pressure target value of the air main pipe is downwards regulated by an amplitude P0;
c. when the dissolved oxygen concentration DO in more than half of the biological cells is less than the minimum MIN, the air manifold pressure target value is adjusted up by an amplitude P1.
Preferably, the butterfly valve opening auxiliary limit value: the F0 value is 25% -60%, and the F1 value is 60% -100%.
Preferably, the regulating amplitude P0 of the air manifold pressure is 0.3-0.5 kilopascals; the pressure regulating amplitude P1 of the air main pipe is 0.7-1 kilopascal.
Preferably, in the step (5), the difference between the actual value and the target value of the air manifold pressure is set as D, and when the absolute value of D is less than or equal to 0.2 kilopascals, the blower unit does not act; when the absolute value of D is more than 0.2 kilopascals, the blower unit acts to adjust the actual value of the air manifold pressure to the target value.
Preferably, the method for calculating the average value a of the change rate of the dissolved oxygen concentration per 20 seconds in the previous minute in the step (2) is as follows:
assuming that the measured values of the dissolved oxygen concentration at 20 second intervals in the previous minute are A0, A1, A2, A3, the average value of the change rate of the dissolved oxygen concentration at 20 second intervals in the previous minute。
Preferably, the change interval of the dissolved oxygen concentration DO takes the value: the minimum value MIN is 0.8-1.2 mg/L, the lower limit value L is 1.5-1.8 mg/L, the upper limit value H is 2-2.3 mg/L, and the maximum value MAX is 2.5-3 mg/L.
Preferably, an air flow meter is mounted at the rear of each butterfly valve.
Preferably, the on-line dissolved oxygen meter is arranged at the tail end of the aeration pipeline of the biological tank.
The invention has the beneficial effects that:
1. the traditional aeration method generally adjusts the air quantity distribution according to the calculated air quantity, but because the actual air quantity of the biological pool is related to various factors such as the efficiency of an aeration head, the length of an aeration pipeline, the flow rate and the mixing state of the biological pool and the like, the calculation of the air quantity and the actual deviation are quite large. In order to solve the problem that the continuous change of water quantity, water quality and water temperature can cause the continuous change of the oxygen demand of an aeration system, the aeration method of the invention adjusts the air quantity distribution in real time through a butterfly valve according to the actual measured change of the dissolved oxygen concentration, thereby realizing accurate aeration and overcoming the defects of large deviation and high energy consumption of the traditional aeration method.
2. According to the technical scheme, the air quantity is reasonably adjusted by setting the action amplitude and the adjustment interval time of the butterfly valve in different areas according to the structural characteristics of the air butterfly valve, the problem of reaction hysteresis of dissolved oxygen is solved, frequent butterfly valve adjustment is avoided, the system pressure is relatively stable, the accurate control effect is achieved, the service life of equipment is prolonged, and finally the aim of saving energy is achieved.
3. According to the technical scheme, by setting 4 limit values and 5 intervals of the change range of the dissolved oxygen concentration DO and setting different air butterfly valve action rules according to different interval ranges, the dissolved oxygen is accurately controlled in a certain range, the water quality of the discharged water is not affected during the reduction, and the aeration is not wasted during the rising.
4. In the technical scheme of the invention, the auxiliary limit value F0-F1 of the butterfly valve opening can be set, when a certain number of biological pool butterfly valve opening reaches an auxiliary lower limit and still needs to be adjusted downwards, the pressure and the air quantity of the whole air main pipe are directly regulated, when a certain number of biological pool butterfly valve opening reaches an auxiliary upper limit and still needs to be adjusted upwards, the pressure and the air quantity of the whole air main pipe are directly regulated to improve, and the setting of the auxiliary lower limit F0 ensures that the pressure of the main pipe is kept in a lowest and most energy-saving state under the condition that the aeration quantity meets the requirements of the biological pool; the auxiliary upper limit F1 is set so that the other part of the biological tanks are not excessively aerated under the condition that the aeration amount of one part of the biological tanks is satisfied.
5. In the accurate aeration system in the prior art, the pressure change range of the air manifold is very small or is controlled completely by constant pressure, when the dissolved oxygen is high, the opening of the valve of the air pipeline is reduced to maintain the pressure within the range, and at the moment, the power consumption of a fan is increased, and the energy consumption is very large. According to the technical scheme, the air manifold pressure of the control system can be adjusted in real time, so that the air manifold pressure is always kept in the lowest state under the condition of meeting the air quantity requirement. Not only achieves the effect of accurate aeration, but also achieves the purposes of energy conservation and consumption reduction.
6. In general, when the air manifold pressure is regulated by the air quantity of the air blower, the air blower acts as long as the manifold pressure changes, but the action of each butterfly valve causes slight change of the air manifold pressure; in the traditional control mode, any slight change of the air manifold pressure can cause the air blower to act, so that the air blower frequently adjusts the opening degree of the guide vane, the energy consumption is very high, and the loss of the air blower is also very high.
7. At present, the existing precise aeration technology requires an air flow meter, an online dissolved oxygen meter, an air electric butterfly valve, an air temperature sensor, a water temperature sensor and the like to be arranged on each aerobic corridor of each biological pond, and equipment purchasing cost and maintenance cost are high. According to the technical scheme, the control system is optimized, only the pressure gauge is arranged on the air main pipe, and each biological pond is provided with the on-line dissolved oxygen meter, the electric regulating butterfly valve and the air flowmeter, so that dependence on the on-line meters is reduced, and equipment purchasing and later maintenance costs are greatly saved.
8. The technical scheme of the invention is suitable for upgrading and reforming various large and medium-sized sewage treatment plants, can be reformed on the basis of the existing facilities, is convenient to realize, is simple to control, and is mainly very energy-saving.
Drawings
FIG. 1 is a schematic diagram of a control system for the precise aeration method for sewage treatment according to the present invention.
Detailed Description
The following examples are given to illustrate the invention in detail, but are not intended to limit the scope of the invention in any way. The equipment elements referred to in the following examples are conventional equipment elements unless otherwise specified; the industrial materials are commercially available conventional industrial materials unless otherwise specified.
Example 1: an accurate aeration method for sewage treatment, which comprises the following steps:
(1) Introducing sewage to be treated into four biological tanks, wherein the biological tanks are provided with an aeration system in a matching way, the aeration system comprises a controller, a blower unit and aeration pipelines respectively arranged in the biological tanks, the aeration pipelines in each biological tank are communicated with an external air main pipe through split pipes, butterfly valves are respectively arranged on the split pipes corresponding to each biological tank, a pressure gauge is arranged on the air main pipe, the blower unit is correspondingly connected with the air main pipe, and online dissolved oxygen measuring instruments are respectively arranged in the biological tanks; the butterfly valve, the blower unit, the pressure gauge and the online dissolved oxygen meter are respectively and correspondingly electrically connected with the controller; an air flow meter is arranged at the rear part of each butterfly valve; wherein, the online dissolved oxygen meter is arranged at the tail end of the aeration pipeline of the biological pond. The schematic diagram of the control system is shown in fig. 1, the controller comprises a main controller, sub controllers and sub station controllers, the number of the sub station controllers is equal to that of the biological pools, the on-line dissolved oxygen measuring instrument and the butterfly valve of each biological pool are respectively and correspondingly connected with one sub station controller, the sub station controllers are respectively and correspondingly connected with the sub controllers, and the air pressure gauge is correspondingly connected with the sub controllers; the sub-controllers are correspondingly connected with the blower units through MCP interfaces; the main controller and the sub controllers are communicated through Ethernet. The main controller, the sub controller and the sub station controller are PLC controllers of Siemens 6ES7 series.
The sub-controllers are connected with the air blower group through MCP interfaces and used for acquiring state information of the air blowers and controlling actions of the air blowers, each biological pond is provided with a sub-station controller and used for transmitting data of the online dissolved oxygen meter and the butterfly valve to the sub-control station, pressure gauge information on the air manifold is also transmitted to the sub-controllers, and the main controller acquires various data acquired by the sub-control station through the Ethernet, processes the data and sends out corresponding control signals to control the operation of the whole system.
(2) The dissolved oxygen concentration DO in each biological pool is measured by an online dissolved oxygen meter, and the average value A of the change rate of the dissolved oxygen concentration in the previous minute every 20 seconds is calculated by a controller, so that the change interval of the dissolved oxygen concentration DO is set: minimum value MIN < lower limit value L < upper limit value H < maximum value MAX;
wherein, the change interval of the dissolved oxygen concentration DO takes the value as follows: the minimum value MIN is 1mg/L, the lower limit value L is 1.5mg/L, the upper limit value H is 2mg/L, and the maximum value MAX is 2.5mg/L.
The average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is calculated by:
assuming that the measured values of the dissolved oxygen concentration at 20 second intervals in the previous minute are A0, A1, A2, A3, the average value of the change rate of the dissolved oxygen concentration at 20 second intervals in the previous minute。
(3) The current opening of each biological pond corresponding to the butterfly valve is obtained, and the butterfly valve adjusting amplitude and the time interval are obtained according to the opening interval of the butterfly valve shown in the following table 1:
(4) The opening degree of the butterfly valve is adjusted according to the following conditions:
(1) when DO is smaller than MIN, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0.03, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(2) when MIN is less than or equal to DO and less than L, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(3) when L is less than or equal to DO is less than or equal to H, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than 0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1; if A is less than-0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1; if A is more than or equal to-0.03 and less than or equal to 0.03, the opening of the butterfly valve of the biological pool is kept unchanged.
(4) When H is less than DO and less than or equal to MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is more than 0, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjusting amplitude shown in the table 1;
(5) when DO is more than MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to-0.03, the butterfly valve of the biological pool is kept unchanged in opening degree; if A > -0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1;
(5) Setting an air main pressure target value according to the aeration amount required by each biological pond, comparing the actual air main pressure value detected by a pressure gauge with the target value, and adjusting the air outlet amount of a blower unit by controlling the opening amount of the blowers and the opening degree of the guide vanes of the blowers when the actual air main pressure value and the target value are inconsistent, so as to adjust the air main pressure to the target value;
the method for adjusting the pressure target value of the air manifold comprises the following steps:
a. firstly, setting the auxiliary limit value of the butterfly valve opening of each biological pool as F0-F1, and when the butterfly valve opening reaches F0 and still needs to be adjusted downwards, namely the biological pool is in a descending request state; when the opening of the butterfly valve reaches F1 and still needs to be adjusted upwards, namely the biological pool is in a lifting request state; wherein f0=40%, f1=80%. In the practical application process, because the biological tanks, the air main pipe and the blower units are distributed differently, different biological tank aeration pipelines may have different lengths, and in addition, the aeration effect of each biological tank aeration head may also have different values, so that the butterfly valve opening auxiliary limit value of each biological tank can be set to different values. Setting an auxiliary lower limit to enable the aeration quantity to keep the pressure of a main pipe in a lowest and most energy-saving state under the condition of meeting the requirements of the biological pond; the auxiliary upper limit is set so that the biological tank is not excessively aerated under the condition that the aeration quantity of other biological tanks is met.
b. Acquiring a request state of a biological pool every ten minutes, and when at least two biological pools are in a rising request state, adjusting the pressure target value of the air main pipe by an amplitude P0; when at least two biological pools are in a descending request state, the pressure target value of the air main pipe is downwards regulated by an amplitude P0; wherein p0=0.3 kpa.
c. When more than half of the dissolved oxygen concentration DO < MIN in the biological pond, the air manifold pressure target value is adjusted up by an amplitude P1, wherein p1=0.7 kpa.
In the air manifold pressure regulating process, setting the difference value between the actual value and the target value of the air manifold pressure as D, and when the absolute value of D is less than or equal to 0.2 kilopascals, the blower unit does not act; when the absolute value of D is more than 0.2 kilopascals, the blower unit acts to adjust the actual value of the air manifold pressure to the target value. That is, a dead zone of the blower is set, when the pressure of the air main pipe changes slightly (within 0.2 kilopascals), the blower cannot act due to the pressure change of the air main pipe, and only when the pressure change value of the air main pipe is larger than 0.2 kilopascals, the blower acts, so that the operating frequency of the blower is reduced, the service life of the blower is prolonged, and the purpose of saving energy is achieved.
(6) After aeration is completed, the sewage treatment process is carried out in the next step.
The sewage treatment accurate aeration method of the invention has the working mode that:
firstly, sewage to be treated is introduced into a biological pond, the quantity of the biological ponds can be set according to specific conditions, aeration pipelines are arranged, 4 biological ponds are arranged in the embodiment 1, an online dissolved oxygen meter is arranged in each biological pond, the aeration pipelines are arranged in the biological ponds and are communicated with an external air main pipe through split pipes, and butterfly valves are arranged on the split pipes corresponding to each biological pond.
Before aeration, the upper limit value and the lower limit value of the air main pipe pressure are set through calculation of the air demand, the air main pipe pressure is regulated in a limiting range in the aeration process, and the butterfly valve opening interval of each biological pond is set through calculation of the air demand and the total air demand of each biological pond, so that the butterfly valve of each biological pond is regulated in an interval range. Such as: when the dissolved oxygen concentration DO of a biological pool is less than 1mg/L, judging the opening interval of a butterfly valve, and if the opening of the butterfly valve is between 0 and 30 percent, and the average value A of the change rate of the dissolved oxygen concentration of the biological pool every 20 seconds in the previous minute is more than or equal to 0.03, keeping the opening of the butterfly valve of the biological pool unchanged; if A is less than 0.03, the butterfly valve is adjusted up by 1% every 120 seconds. Judging the opening interval of the cut-off butterfly valve when the dissolved oxygen concentration DO of one biological pool is in the range of 1 mg/L-1.5 mg/L, and if the opening of the butterfly valve is between 60 and 100 percent and the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0, keeping the opening of the butterfly valve of the biological pool unchanged; if A < 0, the butterfly valve is adjusted up by 10% of opening every 1000 seconds. And (4) adjusting the opening of the butterfly valve by analogy according to the method in the step (4).
When the air quantity in the system cannot reach balance by butterfly valve adjustment, the system adjusts the air main pipe pressure to match the total air quantity required by the system, so that the balance intelligent regulation and control of the dissolved oxygen in each biological pond in the range are achieved. The regulation and control of the air main pressure is based on the ascending and descending request state of the biological pools, firstly, the butterfly valve opening auxiliary limit value F0-F1 (such as 40% -80% or other) of each biological pool is set, and when the butterfly valve opening reaches F0 and still needs to be regulated downwards, the biological pool is in the descending request state; when the opening of the butterfly valve reaches F1 and still needs to be adjusted upwards, namely the biological pool is in a lifting request state; acquiring a request state of the biological pools every ten minutes, and when at least two biological pools are in a rising request state, adjusting the pressure target value of the air manifold by an amplitude (0.3 kilopascal); when at least two biological pools are in a descending request state, the pressure target value of the air main pipe is regulated downwards (0.3 kilopascal); when more than half of the dissolved oxygen concentration DO in the biological cells is less than the minimum MIN, the air manifold pressure is insufficient to meet the air demand of most biological cells, and the air manifold pressure target value is adjusted upwards by a larger amplitude (0.7 kilopascals).
When the actual value of the air manifold pressure changes, the air blower can act to adjust the air manifold pressure to be consistent with the target value. However, in order to prevent frequent actions of the air blower caused by the small change of the pressure of the air main pipe, a dead zone of the action of the air blower is arranged, when the change value of the pressure of the air main pipe is less than or equal to 0.2 kilopascal, the air blower does not act, and only when the change value of the pressure of the air main pipe is greater than 0.2 kilopascal, the air blower acts to adjust the pressure of the air main pipe. Therefore, frequent actions of the blower can be greatly reduced, and the purposes of prolonging the service life of the blower and saving energy are achieved.
According to the aeration control method, the upper limit value and the lower limit value of the air main pipe pressure are set through calculation of the air demand, so that the air main pipe pressure is regulated within a limiting range, and the butterfly valve opening interval of each biological pond is set through calculation of the air demand and the total air demand of each biological pond, so that the butterfly valve of each biological pond is regulated within an interval range; when the air quantity in the system cannot reach balance by butterfly valve adjustment, the system adjusts the air main pipe pressure to match the total air quantity required by the system, so that the balance intelligent regulation and control of the dissolved oxygen in each biological pond in the range are achieved.
While the invention has been described with reference to the embodiments, those skilled in the art will understand that various specific parameters in the above embodiments may be changed without departing from the spirit of the invention, and thus a plurality of specific embodiments are common variation ranges of the invention, and will not be described in detail herein.
Claims (10)
1. The precise aeration method for sewage treatment is characterized by comprising the following steps:
(1) Introducing sewage to be treated into more than two biological tanks, wherein the biological tanks are provided with an aeration system in a matching way, the aeration system comprises a controller, a blower unit and aeration pipelines respectively arranged in the biological tanks, the aeration pipelines in each biological tank are communicated with an external air main pipe through a shunt pipe, butterfly valves are respectively arranged on the shunt pipes corresponding to each biological tank, a pressure gauge is arranged on the air main pipe, the blower unit is correspondingly connected with the air main pipe, and online dissolved oxygen measuring instruments are respectively arranged in the biological tanks; the butterfly valve, the blower unit, the pressure gauge and the online dissolved oxygen meter are respectively and correspondingly electrically connected with the controller;
(2) The dissolved oxygen concentration DO in each biological pool is measured by an online dissolved oxygen meter, and the average value A of the change rate of the dissolved oxygen concentration in the previous minute every 20 seconds is calculated by a controller, so that the change interval of the dissolved oxygen concentration DO is set: minimum value MIN < lower limit value L < upper limit value H < maximum value MAX;
(3) The current opening of each biological pond corresponding to the butterfly valve is obtained, and the butterfly valve adjusting amplitude and the time interval are obtained according to the opening interval of the butterfly valve shown in the following table 1:
(4) The opening degree of the butterfly valve is adjusted according to the following conditions:
(1) when DO is smaller than MIN, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0.03, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(2) when MIN is less than or equal to DO and less than L, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is less than 0, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1;
(3) when L is less than or equal to DO is less than or equal to H, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is more than 0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1; if A is less than-0.03, the opening of the butterfly valve is adjusted upwards according to the time interval and the adjustment amplitude shown in the table 1; if A is more than or equal to-0.03 and less than or equal to 0.03, the opening of the butterfly valve of the biological pool is kept unchanged;
(4) when H is less than DO and less than or equal to MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to 0, the opening of a butterfly valve of the biological pool is kept unchanged; if A is more than 0, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjusting amplitude shown in the table 1;
(5) when DO is more than MAX, if the average value A of the change rate of the dissolved oxygen concentration every 20 seconds in the previous minute is less than or equal to-0.03, the butterfly valve of the biological pool is kept unchanged in opening degree; if A > -0.03, the opening of the butterfly valve is adjusted downwards according to the time interval and the adjustment amplitude shown in the table 1;
(5) Setting an air main pressure target value according to the aeration amount required by each biological pond, comparing the actual air main pressure value detected by a pressure gauge with the target value, and adjusting the air outlet amount of a blower unit by controlling the opening amount of the blowers and the opening degree of the guide vanes of the blowers when the actual air main pressure value and the target value are inconsistent, so as to adjust the air main pressure to the target value;
(6) After aeration is completed, the sewage treatment process is carried out in the next step.
2. The precise aeration method for sewage treatment according to claim 1, wherein the method for adjusting the target value of the air manifold pressure in the step (5) is as follows:
a. firstly, setting the auxiliary limit value of the butterfly valve opening of each biological pool as F0-F1, and when the butterfly valve opening reaches F0 and still needs to be adjusted downwards, namely the biological pool is in a descending request state; when the opening of the butterfly valve reaches F1 and still needs to be adjusted upwards, namely the biological pool is in a lifting request state;
b. acquiring a request state of a biological pool every ten minutes, and when at least two biological pools are in a rising request state, adjusting the pressure target value of the air main pipe by an amplitude P0; when at least two biological pools are in a descending request state, the pressure target value of the air main pipe is downwards regulated by an amplitude P0;
c. when the dissolved oxygen concentration DO in more than half of the biological cells is less than the minimum MIN, the air manifold pressure target value is adjusted up by an amplitude P1.
3. The precise aeration method for sewage treatment according to claim 2, wherein the butterfly valve opening degree is an auxiliary limit value: the F0 value is 25% -60%, and the F1 value is 60% -100%.
4. The precise aeration method for sewage treatment according to claim 2, wherein the adjustment range P0 of the air manifold pressure is 0.3 to 0.5 kpa; the pressure regulating amplitude P1 of the air main pipe is 0.7-1 kilopascal.
5. The precise aeration method for sewage treatment according to claim 2, wherein in the step (5), the difference between the actual value and the target value of the air main pressure is set as D, and when the absolute value of D is less than or equal to 0.2 kpa, the blower unit does not act; when the absolute value of D is more than 0.2 kilopascals, the blower unit acts to adjust the actual value of the air manifold pressure to the target value.
6. The precise aeration method for sewage treatment according to claim 1, wherein the method for calculating the average value a of the change rate of the dissolved oxygen concentration per 20 seconds in the previous minute in step (2) is as follows:
assuming that the measured values of the dissolved oxygen concentration at 20 second intervals in the previous minute are A0, A1, A2, A3, the average value of the change rate of the dissolved oxygen concentration at 20 second intervals in the previous minute。
7. The precise aeration method for sewage treatment according to claim 1, wherein the change interval of the dissolved oxygen concentration DO takes the value of: the minimum value MIN is 0.8-1.2 mg/L, the lower limit value L is 1.5-1.8 mg/L, the upper limit value H is 2-2.3 mg/L, and the maximum value MAX is 2.5-3 mg/L.
8. The precise aeration method for sewage treatment according to claim 1, wherein an air flow meter is installed at the rear of each butterfly valve.
9. The precise aeration method for sewage treatment according to claim 1, wherein the on-line dissolved oxygen meter is provided at the end of the aeration pipe of the biological tank.
10. The precise aeration method for sewage treatment according to claim 1, wherein the controller is a PLC controller of siemens 6ES7 series.
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| CN108678986B (en) * | 2018-05-18 | 2019-08-09 | 清华大学 | The control method and device of the automatic adjustment of sewage treatment plant's air blower and marshalling operation |
| CN108751401B (en) * | 2018-06-22 | 2020-12-22 | 北京碧水源科技股份有限公司 | MBR (membrane bioreactor) combined process air blowing system and operation method thereof |
| CN109111030B (en) * | 2018-08-27 | 2021-12-07 | 重庆固润科技发展有限公司 | Integrated sewage treatment intelligent control system and control method |
| CN109592804B (en) * | 2018-12-28 | 2023-09-05 | 中原环保股份有限公司 | Sewage treatment near-optimal precise aeration method |
| CN109534493B (en) * | 2019-01-17 | 2021-09-21 | 重庆市李家沱排水有限公司 | Sewage treatment aeration precise control system and control method thereof |
| CN111848455B (en) * | 2020-08-17 | 2023-05-30 | 万华化学集团股份有限公司 | Method for reducing chromaticity of isocyanate product and automatic control method for gas phase extraction flow of isocyanate rectifying tower |
| CN112010436B (en) * | 2020-08-25 | 2021-03-30 | 广州众行环保科技有限公司 | Method for accurately controlling dissolved oxygen in sewage treatment process |
| CN114956360B (en) * | 2022-08-02 | 2022-10-21 | 江苏莱通环境科技有限公司 | Sewage treatment aeration oxygenation control method based on hill climbing algorithm |
| CN116216913B (en) * | 2023-02-20 | 2023-12-05 | 浙江数翰科技有限公司 | MBBR pulse aeration control method and system |
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