CN118026389A - Two-stage AO-ABFT process aeration control system and method - Google Patents
Two-stage AO-ABFT process aeration control system and method Download PDFInfo
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- 238000005273 aeration Methods 0.000 title claims abstract description 154
- 238000000034 method Methods 0.000 title claims abstract description 56
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 158
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 158
- 239000001301 oxygen Substances 0.000 claims abstract description 158
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 claims abstract description 66
- 230000001105 regulatory effect Effects 0.000 claims abstract description 34
- 238000005243 fluidization Methods 0.000 claims abstract description 21
- 238000012544 monitoring process Methods 0.000 claims abstract description 15
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 78
- 238000004364 calculation method Methods 0.000 claims description 21
- 239000007789 gas Substances 0.000 claims description 14
- 239000010802 sludge Substances 0.000 claims description 9
- 229910002651 NO3 Inorganic materials 0.000 claims description 6
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 claims description 6
- 239000002351 wastewater Substances 0.000 claims description 5
- 238000012821 model calculation Methods 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 17
- 239000010865 sewage Substances 0.000 abstract description 7
- 230000000694 effects Effects 0.000 abstract description 6
- 230000001788 irregular Effects 0.000 abstract description 3
- 238000004134 energy conservation Methods 0.000 abstract description 2
- 239000011259 mixed solution Substances 0.000 description 10
- 229920006395 saturated elastomer Polymers 0.000 description 8
- 239000007788 liquid Substances 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910052799 carbon Inorganic materials 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000005540 biological transmission Effects 0.000 description 4
- 239000003344 environmental pollutant Substances 0.000 description 3
- 231100000719 pollutant Toxicity 0.000 description 3
- 238000004065 wastewater treatment Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000011065 in-situ storage Methods 0.000 description 2
- 239000000523 sample Substances 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000005842 biochemical reaction Methods 0.000 description 1
- 230000031018 biological processes and functions Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000004090 dissolution Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 244000005700 microbiome Species 0.000 description 1
- 230000001483 mobilizing effect Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- Activated Sludge Processes (AREA)
- Purification Treatments By Anaerobic Or Anaerobic And Aerobic Bacteria Or Animals (AREA)
Abstract
The invention discloses a two-stage AO-ABFT process aeration control system and a method. In order to solve the problems that the change of aeration quantity to the change of dissolved oxygen in the prior art has irregular time lag, the delay of PID automatic control is larger, and the control effect is not ideal enough; the invention comprises the following steps: an anoxic-aerobic tank and an aeration biological fluidization tank which are connected in sequence; the branch extends to the aerobic tank and the aeration biological fluidization tank, and air is input; the PLC control system is used for receiving monitoring data of each sensor arranged in the anoxic-aerobic tank and the aeration biological fluidization tank and calculating the required air inflow; the PLC control system receives the state of the electric regulating valve arranged on the aeration pipeline, and adjusts the opening of the electric regulating valve according to the calculated required air inflow. Based on multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen, the stability of the sewage treatment system is improved, and the energy conservation and consumption reduction of the sewage treatment process are realized.
Description
Technical Field
The invention relates to the technical field of wastewater treatment, in particular to a two-stage AO-ABFT process aeration control system and method.
Background
Biological processes are currently the most widely used wastewater treatment technology. The two-stage AO-ABFT technology, i.e. a two-stage anoxic-oxic-aerated biological fluidized tank, utilizes the biochemical reaction of aerobic, facultative and/or anaerobic microorganisms to decompose pollutants such as COD (Chemical Oxygen Demand ), BOD (biochemical 1 Oxygen Demand), NH3-N (ammonia nitrogen content index), TN (total nitrogen), TP (total phosphorus) and the like in the wastewater by artificially controlling the Oxygen content of the wastewater, thereby realizing the efficient purification of the wastewater.
The control of the dissolved oxygen is directly related to the running condition of the blower, the water inlet load and the air supply valve adjustment, and is an important factor influencing the treatment effect of the two-stage AO-ABFT process. Meanwhile, the aeration unit is also an important energy consumption unit. Excessive aeration generally does not cause obvious fluctuation of the water quality of the effluent of the system, but obvious energy consumption and waste exist.
At present, an aeration unit in the sewage biological treatment process generally adopts manual in-situ control and PID (proportion-integral-derivative) automatic control. In recent years, in order to prevent the leakage of the odor and meet the environmental protection requirement, more and more biochemical tanks adopt a closed cover design, and the aeration condition of the biochemical tanks cannot be observed. Moreover, since dissolution and removal of gas are a delayed process, it takes a long time to reach equilibrium, and the change of aeration quantity affecting dissolved oxygen is nonlinear and time-varying, the manner of performing aeration control by manual in-situ control has not been applied.
PID automatic control, namely, comparing the dissolved oxygen control expected signal and the dissolved oxygen feedback signal in the aeration control area, and performing fixed value adjustment on the electric valve according to the dissolved oxygen deviation so as to change the aeration quantity, thereby realizing the automatic control of the dissolved oxygen. For example, a device and a method for realizing energy saving by stably maintaining micro-expansion of sludge in a biological denitrification process are disclosed in Chinese patent literature, the device is provided with a water inlet tank, a reactor and a secondary sedimentation tank in sequence, an anoxic cell is arranged at the water inlet end of the reactor, a stirrer is arranged in the chamber, an aerobic cell or a corridor is arranged behind the anoxic cell, dissolved oxygen probes and aeration heads are arranged in the anoxic cell, each dissolved oxygen probe is connected with a PID control system, each aeration head is connected with an air compressor through an air flowmeter, and each control switch is connected with the PID control system. The process is controlled to operate under the proper sludge load and dissolved oxygen concentration conditions by reasonably regulating and controlling the operation parameters of the process.
However, as described above, the change from the aeration rate to the change of the dissolved oxygen has irregular time lag, and the delay of the PID automatic control is large, so that the control effect is not ideal.
Disclosure of Invention
The invention mainly solves the problems that the change of aeration quantity to the change of dissolved oxygen in the prior art has irregular time lag, the delay of PID automatic control is larger, and the control effect is not ideal enough; the two-stage AO-ABFT process aeration control system and method based on COD, ammonia nitrogen and dissolved oxygen feedback are provided, the stability of a sewage treatment system is improved by monitoring the inflow water flow and simultaneously based on multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen, and the energy conservation and consumption reduction of the sewage treatment process are realized.
The technical problems of the invention are mainly solved by the following technical proposal:
A two-stage AO-ABFT process aeration control system comprising:
the anoxic-aerobic tank comprises an anoxic tank and an aerobic tank which are connected in sequence to decompose wastewater;
The aeration biological fluidization pool is connected with the anoxic-aerobic pool and outputs treated water;
The branch extends to the aerobic tank and the aeration biological fluidization tank, and air is input;
The PLC control system is used for receiving monitoring data of each sensor arranged in the anoxic-aerobic tank and the aeration biological fluidization tank and calculating the required air inflow;
the PLC control system receives the state of the electric regulating valve arranged on the aeration pipeline, and adjusts the opening of the electric regulating valve according to the calculated required air inflow.
In the scheme of the embodiment, in the two-stage AO-ABFT process, the influence of the previous aerobic section on the subsequent anoxic section is avoided on the one hand, the carbon reduction denitrification dephosphorization efficiency is improved, and the stable standard of the effluent quality is ensured by monitoring the inflow water flow and simultaneously based on the multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen; on the other hand, through the calculation of the aeration control model, real-time accurate aeration is realized, and the operation energy consumption is saved.
Preferably, the anoxic-aerobic tank is a multi-stage anoxic-aerobic tank, and the multi-stage anoxic-aerobic tanks are sequentially connected.
In the scheme of the application, the two-stage anoxic-aerobic tanks are adopted, so that the cost of arranging the multi-stage anoxic-aerobic tanks is saved while the wastewater treatment efficiency is ensured.
Preferably, the sensor arranged in the anoxic tank comprises a COD detector and an ammonia nitrogen detector; the sensor arranged in the aerobic tank is a dissolved oxygen meter; the sensors arranged in the aeration biological fluidization pool comprise a COD detector, an ammonia nitrogen detector and a dissolved oxygen meter.
Because the specific conditions of each biochemical pond are different, the first aerobic pond, the second aerobic pond and the ABFT are provided with an online dissolved oxygen meter, the real-time air quantity calculation and the feedback adjustment are carried out through a PLC control system, the dissolved oxygen value is compared in real time, and the precise control of the aeration quantity of each biochemical pond and the reduction of the energy consumption are realized by utilizing the variable frequency adjustment of an air blower and the opening adjustment of an electric adjusting valve.
Preferably, the aeration pipeline comprises a main pipeline and a branch pipeline; one end of a branch of the aeration pipeline is connected with a blower, and the other end of the aeration pipeline is emptied; the main way of the aeration pipeline extends a plurality of branches, and the branches of the aeration pipeline are respectively connected with the bottoms of the aerobic tank and the aeration biological fluidization tank.
Preferably, a pressure transmitter is arranged on one side of the main way of the aeration pipeline close to the blower, and a mobilizing and regulating valve is arranged on one side of the main way of the aeration pipeline, which is empty; an electric regulating valve and an air flow meter are respectively arranged on the branch of the aeration pipeline.
Because the specific conditions of each biochemical pond are different, in order to further stabilize dissolved oxygen and reduce energy consumption, the main road of the aeration pipeline is provided with a pressure transmitter, the first branch road, the second branch road and the third branch road are respectively provided with an electric regulating valve and an air flow meter, and the blow-down pipeline is provided with an electric regulating valve, so that the aeration quantity of each biochemical pond is respectively controlled by a PLC control system.
Preferably, the water inlet pipe is connected with the top of the anoxic tank, and a water inlet flowmeter is arranged on the water inlet pipe. Is used for monitoring the inflow.
A two-stage AO-ABFT process aeration control method comprises the following steps:
s1: constructing a two-stage AO-ABFT process aeration control system;
S2: acquiring COD, ammonia nitrogen and dissolved oxygen data of a biochemical combination tank in an aeration control system, and calculating the required air quantity of the biochemical combination tank through an aeration control model;
S3: and (3) opening adjustment is carried out on the electric regulating valve according to the calculated required air quantity, and the air quantity calculation and feedback adjustment are carried out at intervals of rated time.
In the two-stage AO-ABFT process, the influence of the previous aerobic section on the subsequent anoxic section is avoided on the one hand, the carbon reduction denitrification and dephosphorization efficiency is improved, and the stable standard of the effluent quality is ensured by monitoring the inflow water flow and simultaneously based on the multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen; on the other hand, through the calculation of the aeration control model, real-time accurate aeration is realized, and the operation energy consumption is saved.
Preferably, the aeration control model calculation process is as follows:
1) For the target biochemical pool, calculating the actual oxygen demand by weighting according to the COD difference value and the ammonia nitrogen difference value of the monitored inflow water and the outflow water of the target biochemical pool;
2) Calculating a clear water average dissolved oxygen value from the underwater depth of the aeration device to the tank surface according to the oxygen content in the gas escaping from the aeration tank;
3) Calculating the oxygen demand in a standard state according to the calculated average dissolved oxygen value and the actual oxygen demand and the dissolved oxygen obtained by monitoring in the target biochemical pool;
4) And calculating the required gas quantity according to the oxygen utilization rate of the aeration device and the calculated standard state oxygen demand.
The PLC control system calculates the required gas amount according to the data collected by monitoring COD, dissolved oxygen, ammonia nitrogen amount and the like.
Preferably, the biodegradability and the inflow water flow rate of the mixed solution in the target biochemical pool are used as weighting coefficients of COD concentration differences, the ratio of the volatile suspended matter concentration MLVSS of the mixed solution to the suspended matter concentration MLSS of the mixed solution is used as the weighting coefficients of the total residual sludge, and the actual oxygen demand is obtained by weighting calculation by combining the ammonia nitrogen concentration differences between the inflow water and the outflow water and the reduced nitrate amount.
For the target biochemical tank, the actual oxygen demand is obtained by weighting calculation according to the COD concentration difference between the inlet water and the outlet water, the ammonia nitrogen concentration difference, the reduced nitrate amount and the total residual sludge.
Preferably, the actual dissolved oxygen value is compared with the set dissolved oxygen low value, dissolved oxygen high value and dissolved oxygen high value at each interval of the rated time, and the opening degree of the electric control valve and the blower frequency are adjusted.
The beneficial effects of the invention are as follows:
In the two-stage AO-ABFT process, the influence of the previous aerobic section on the subsequent anoxic section is avoided by monitoring the inflow water flow and simultaneously carrying out multiple feedback adjustment based on COD, ammonia nitrogen and dissolved oxygen, so that the carbon reduction denitrification and dephosphorization efficiency is improved, and the quality of the effluent is ensured to reach the standard stably; on the other hand, through the calculation of the aeration control model, real-time accurate aeration is realized, and the operation energy consumption is saved.
Drawings
FIG. 1 is a schematic diagram of a two-stage AO-ABFT process aeration control system according to the present invention.
FIG. 2 is a flow chart of a two-stage AO-ABFT process aeration control method of the present invention.
In the figure, a biochemical combination tank 1, a PLC control system 2, a water inlet flowmeter 3, a blower 4, a pressure transmitter 5, an electric regulating valve 6, an air flowmeter 7, an 8 COD detector 9, a dissolved oxygen detector 10, an ammonia nitrogen detector 11, a first anoxic tank 12, a first aerobic tank 13, a second anoxic tank 14, a second aerobic tank 15 and an aeration biological fluidization tank.
Detailed Description
The technical scheme of the invention is further specifically described below through examples and with reference to the accompanying drawings.
Embodiment one:
The two-stage AO-ABFT process aeration control system in the embodiment, as shown in figure 1, comprises a biochemical combination tank 1, a PLC control system 2, a water inlet pipe and an aeration pipeline.
The biochemical combination tank 1 comprises a first anoxic tank 11, a first aerobic tank 12, a second anoxic tank 13, a second aerobic tank 14 and an Aeration Biological Fluidization Tank (ABFT) 15 which are sequentially connected.
The water inlet pipe is provided with a water inlet flow meter 3, and is connected with the top of the anoxic tank in the biochemical combination tank 1, and in the embodiment, the water inlet pipe is connected with the top of the first anoxic tank 11 in the biochemical combination tank 1.
One end of the main road of the aeration pipeline is connected with the blower 4, and the other end of the main road of the aeration pipeline is emptied. The main way of the aeration pipeline is provided with a pressure transmitter 5 and an electric regulating valve 6. Specifically, the pressure transmitter 5 is disposed at one end close to the blower 4, and the electric control valve 6 is disposed at the one end that is vented.
The main road of the aeration pipeline is provided with a plurality of branches, and the branches of the aeration pipeline are respectively connected with the aerobic tank and the ABFT bottom in the biochemical combination tank 1. An electric regulating valve 6 and an air flow meter 7 are respectively arranged on the branch of the aeration pipeline. In order to distinguish the electric control valve on the trunk line of the aeration line from the electric control valve on the branch line, the aeration line trunk line is defined as an emptying line in the present embodiment, and the electric control valve on the aeration line trunk line is referred to as an emptying valve.
An online COD detector 8, an online dissolved oxygen meter 9 and an online ammonia nitrogen detector 10 are respectively arranged in the biochemical combination tank 1. Specifically, an online COD detector 8 and an online ammonia nitrogen detector 10 are arranged in the anoxic tank (comprising a first anoxic tank 11 and a second anoxic tank 13); an online dissolved oxygen meter 9 is arranged in each aerobic tank (comprising a first aerobic tank 12 and a second aerobic tank 14); in ABFT, an online COD detector 8, an online dissolved oxygen detector 9, and an online ammonia nitrogen detector 10 are provided.
In the present embodiment, the branch connecting the aeration pipe with the first aerobic tank 12 is positioned as the first branch; defining a branch of the aeration pipeline connected with the second aerobic tank 14 as a second branch; the branch of the aeration line connected to the aeration biological fluidized tank 15 is defined as a third branch.
Because the specific conditions of each biochemical pond are different, in order to further stabilize dissolved oxygen and reduce energy consumption, the main road of the aeration pipeline is provided with a pressure transmitter 5, the first branch road, the second branch road and the third branch road are respectively provided with an electric regulating valve 6 and an air flow meter 7, the blow-down pipeline is provided with an electric regulating valve 6, and the aeration quantity of each biochemical pond is respectively controlled by the PLC control system 2.
In this embodiment, the water inflow flowmeter 3, the pressure transmitter 5, the air flowmeter 7, the online COD detector 8, the online dissolved oxygen meter 9 and the online ammonia nitrogen detector 10 are in signal connection with the PLC control system 2, and the blower 4 and the electric control valve 6 are in signal connection and control connection with the PLC control system 2.
The water inflow of the biochemical combination tank 1 is monitored through the water inflow flowmeter 3, the first anoxic tank 11, the second anoxic tank 13 and the ABFT are monitored through the online COD detector 8 and the online ammonia nitrogen detector 10, the first aerobic tank 12, the second aerobic tank 14 and the ABFT are monitored through the online dissolved oxygen meter 9, and signals are transmitted to the PLC control system 2 for calculation.
Because the specific conditions of each biochemical pond are different, the first aerobic pond 12, the second aerobic pond 14 and the ABFT are provided with an online dissolved oxygen meter 9, the real-time air quantity calculation and feedback adjustment are carried out through the PLC control system 2, the dissolved oxygen value is compared in real time, and the precise control of the aeration quantity of each biochemical pond and the reduction of the energy consumption are realized by utilizing the variable frequency adjustment of the air blower 4 and the opening adjustment of the electric adjusting valve 6.
The PLC control system 2 calculates the required gas amount according to the data collected by monitoring the COD, the dissolved oxygen, the ammonia nitrogen amount and the like.
The calculation process expression of the air quantity required by each specific biochemical pond is as follows:
Wherein G s is the required air quantity;
N O is the standard state oxygen demand;
E A is the oxygen utilization rate of the aeration device.
Further, the expression of the standard state oxygen demand N O is:
Wherein N is the actual oxygen demand;
C S is saturated dissolved oxygen in clear water under standard conditions;
Alpha is the ratio of the value of the total oxygen transmission coefficient K La in the mixed solution to the value of the total oxygen transmission coefficient K La in the clean water;
beta is the ratio of the saturated dissolved oxygen value in the mixed solution to the saturated dissolved oxygen in the clean water;
In this embodiment, the mixed liquid refers to the liquid in the biochemical combination tank; the clear water refers to standard liquid.
C sm is the average dissolved oxygen value of the clear water reaching the pool surface at the underwater depth according to the aeration device;
C O is the residual Dissolved Oxygen (DO) value of the mixed liquor, and T is the temperature of the mixed liquor.
Further, the expression of the actual oxygen demand N is:
Wherein N is the actual oxygen demand;
a is the biodegradability in the mixed liquor, namely the ratio BOD5/COD of the biological oxygen demand to the chemical oxygen demand;
Q is the water inflow;
s O is the COD concentration of the inlet water;
S is the COD concentration of the discharged water;
Δx is total excess sludge;
f is the ratio of the mixed liquor volatile suspended matter concentration MLVSS to the mixed liquor suspended matter concentration MLSS;
NH o is the ammonia nitrogen concentration of the inlet water;
NH is the ammonia nitrogen concentration of the effluent;
is the amount of nitrate to be reduced.
Specifically, the COD concentration detected by the online COD detector 8 in the first anoxic tank 11 is the COD concentration of the inlet water of the first aerobic tank 12; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector 10 in the first anoxic tank 11 is the ammonia nitrogen concentration of the inlet water of the first aerobic tank 12; the COD concentration monitored by the online COD detector 8 in the second anoxic tank 13 is the COD concentration of the effluent of the first aerobic tank 12; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector 10 in the second anoxic tank 13 is the ammonia nitrogen concentration of the effluent of the first aerobic tank 12;
Similarly, for the second aerobic tank 14, the COD concentration monitored by the online COD detector 8 in the second anoxic tank 13 is the COD concentration of the inlet water of the second aerobic tank 14; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector 10 in the second anoxic tank 13 is the ammonia nitrogen concentration of the inlet water of the second aerobic tank 14; the COD concentration monitored by the online COD detector 8 in the aeration biological fluidization tank 15 is the effluent COD concentration of the second aerobic tank 14, and the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector 10 in the aeration biological fluidization tank 15 is the effluent ammonia nitrogen concentration of the second aerobic tank 14.
Further, the expression of the average dissolved oxygen value C sm of the clear water from the underwater depth of the aeration device to the pool surface is as follows:
Wherein C sw is saturated dissolved oxygen at the surface of the clean water;
O t is oxygen contained in the gas escaping from the aeration tank;
p b is the absolute pressure at the aeration device.
Specifically, the expression of oxygen-containing O t in the aeration tank escape gas is:
The PLC control system 2 performs opening adjustment of the electric control valve 6 according to the calculated air amount, adjusts the air amount to a required air amount, and performs calculation and feedback adjustment of the air amount every m seconds (can be set).
At each interval of n seconds (which can be set), comparing the actual dissolved oxygen value DO a with the set dissolved oxygen low value DO ll, dissolved oxygen low value DO 1, dissolved oxygen high value DO h and dissolved oxygen high value DO hh;
If the actual dissolved oxygen value is smaller than the set dissolved oxygen low value, namely DO a＜DOII, opening the electric regulating valve 6; when the opening of the electric regulating valve exceeds the upper limit of the opening by h% (which can be set), the blower 4 is turned up until the actual dissolved oxygen value is equal to or more than the set dissolved oxygen low value, namely DO a≥DOl.
If the actual dissolved oxygen value is larger than the set dissolved oxygen high value, namely DO a＞DOhh, the electric regulating valve 6 is closed; when the opening of the regulating valve is lower than the opening lower limit l% (can be set), the blower 4 regulates down the frequency until the actual dissolved oxygen value is smaller than or equal to the set dissolved oxygen high value DO a≤DOh.
When the frequency of the blower 4 is lower than the lower limit value or the pressure transmitter 5 is higher than the upper limit value, the emptying valve on the air line of the aeration pipeline is opened until the frequency of the blower 4 and the outlet pressure of the blower are at normal values.
In the scheme of the embodiment, in the two-stage AO-ABFT process, the influence of the previous aerobic section on the subsequent anoxic section is avoided on the one hand, the carbon reduction denitrification dephosphorization efficiency is improved, and the stable standard of the effluent quality is ensured by monitoring the inflow water flow and simultaneously based on the multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen; on the other hand, through the calculation of the aeration control model, real-time accurate aeration is realized, and the operation energy consumption is saved.
Through the application of the system in a sewage station of a certain chemical enterprise for 6 months, the system runs stably, and the stability of the system is enhanced while the water quality of the effluent stably meets the standard of the table 1 of the emission standard of pollutants in petrochemical industry (GB 31571-2015). Compared with the system before application, the energy consumption of the main energy-consuming equipment fan of the system is obviously reduced by 20.5%, and the energy-saving effect is obvious.
Embodiment two:
The aeration control method for the two-stage AO-ABFT process in the embodiment, as shown in FIG. 2, comprises the following steps:
s1: and constructing a two-stage AO-ABFT process aeration control system based on COD, ammonia nitrogen and dissolved oxygen feedback.
The system comprises a biochemical combination tank, a PLC control system and an aeration pipeline.
Specifically, the biochemical combination tank comprises a first anoxic tank, a first aerobic tank, a second anoxic tank, a second aerobic tank and an Aeration Biological Fluidization Tank (ABFT) which are sequentially connected. The water inlet pipe is provided with a water inlet flow meter, and is connected with the top of the anoxic tank in the biochemical combination tank.
The aeration pipeline comprises a main road and a branch road, and a plurality of branches are derived from the main road of the aeration pipeline.
One end of the main road of the aeration pipeline is connected with the air blower, and the other end of the main road of the aeration pipeline is emptied. The main road of the aeration pipeline is provided with a pressure transmitter and a vent valve. Specifically, the pressure transmitter sets up the one end that is close to the air-blower, and the relief valve is the electric control valve, and the relief valve sets up the one end at the blowdown.
The branch of the aeration pipeline is respectively connected with the aerobic tank and the ABFT bottom in the biochemical combination tank. An electric regulating valve 6 and an air flow meter 7 are respectively arranged on the branch of the aeration pipeline.
Positioning a branch connected with the aeration pipeline and the first aerobic tank as a first branch; defining a branch circuit for connecting the aeration pipeline with the second aerobic tank as a second branch circuit; and positioning a branch connected with the aeration pipeline and the aeration biological fluidization pool as a third branch. Because the specific conditions of each biochemical pond are different, in order to further stabilize dissolved oxygen and reduce energy consumption, pressure transmitters are arranged on the main paths of the aeration pipelines, electric regulating valves and air flow meters are arranged on the first branch, the second branch and the third branch, and the electric regulating valves on the branches are controlled by a PLC control system to control the aeration quantity of each biochemical pond.
An online COD detector, an online dissolved oxygen meter and an online ammonia nitrogen detector are respectively arranged in the biochemical combination pool.
Specifically, an online COD detector and an online ammonia nitrogen detector are arranged in the anoxic tank (comprising a first anoxic tank and a second anoxic tank); an online dissolved oxygen meter is arranged in each aerobic tank (comprising a first aerobic tank and a second aerobic tank); in the ABFT, an online COD detector, an online dissolved oxygen meter and an online ammonia nitrogen detector are arranged.
The water inlet flowmeter, the pressure transmitter, the air flowmeter, the online COD detector, the online dissolved oxygen detector and the online ammonia nitrogen detector are in signal connection with the PLC control system, and data signals are transmitted and detected;
The blower and the electric regulating valve are in signal connection and control connection with the PLC control system, upload corresponding state data and receive control commands issued by the PCL control system.
S2: and acquiring COD, ammonia nitrogen and dissolved oxygen data of the biochemical combination tank in the aeration control system, and calculating the required air quantity of the biochemical combination tank through an aeration control model.
The water inflow of the biochemical combination pool is monitored through a water inflow flowmeter, the first anoxic pool, the second anoxic pool and the ABFT are monitored through an online COD detector and an online ammonia nitrogen detector, the first aerobic pool, the second aerobic pool and the ABFT are monitored through an online dissolved oxygen meter, and signals are transmitted to a PLC control system for calculation.
Because the specific conditions of each biochemical pond are different, the first aerobic pond, the second aerobic pond and the ABFT are provided with an online dissolved oxygen meter, the real-time air quantity calculation and the feedback adjustment are carried out through a PLC control system, the dissolved oxygen value is compared in real time, and the precise control of the aeration quantity of each biochemical pond and the reduction of the energy consumption are realized by utilizing the variable frequency adjustment of an air blower and the opening adjustment of an electric adjusting valve.
The PLC control system calculates the required gas amount according to the data collected by monitoring COD, dissolved oxygen, ammonia nitrogen amount and the like. The specific process comprises the following steps:
1) And for the target biochemical pool, calculating the actual oxygen demand N by weighting according to the COD difference value and the ammonia nitrogen difference value of the monitored water inlet and outlet of the target biochemical pool.
Specifically, for the first aerobic tank, the COD concentration monitored by the online COD detector in the first anoxic tank is the COD concentration of the inlet water of the first aerobic tank; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector in the first anoxic tank is the ammonia nitrogen concentration of the inlet water of the first aerobic tank; the COD concentration monitored by the online COD detector in the second anoxic tank is the COD concentration of the effluent of the first aerobic tank; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector in the second anoxic tank is the ammonia nitrogen concentration of the effluent of the first aerobic tank;
similarly, for the second aerobic tank, the COD concentration monitored by the online COD detector in the second anoxic tank is the COD concentration of the inlet water of the second aerobic tank; the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector in the second anoxic tank is the ammonia nitrogen concentration of the inlet water of the second aerobic tank; the COD concentration monitored by the online COD detector in the aeration biological fluidization pool is the effluent COD concentration of the second aerobic pool, and the ammonia nitrogen concentration monitored by the online ammonia nitrogen detector in the aeration biological fluidization pool is the effluent ammonia nitrogen concentration of the second aerobic pool.
For the target biochemical tank, the actual oxygen demand N is obtained by weighting calculation according to the COD concentration difference between the inlet water and the outlet water, the ammonia nitrogen concentration difference, the reduced nitrate amount and the total residual sludge; in this embodiment, the biodegradability and inflow rate of the mixed solution in the biochemical tank are used as the weighting coefficients of the COD concentration differences, and the ratio of the mixed solution volatile suspended matter concentration MLVSS to the mixed solution suspended matter concentration MLSS is used as the weighting coefficient of the total surplus sludge for weighted calculation. The specific expression of the actual oxygen demand N is as follows:
Wherein N is the actual oxygen demand;
a is the biodegradability in the mixed liquor, namely the ratio BOD5/COD of the biological oxygen demand to the chemical oxygen demand;
Q is the water inflow;
s O is the COD concentration of the inlet water;
S is the COD concentration of the discharged water;
Δx is total excess sludge;
f is the ratio of the mixed liquor volatile suspended matter concentration MLVSS to the mixed liquor suspended matter concentration MLSS;
NH o is the ammonia nitrogen concentration of the inlet water;
NH is the ammonia nitrogen concentration of the effluent;
is the amount of nitrate to be reduced.
In this embodiment, the mixed liquid refers to the liquid in the biochemical combination tank; the clear water refers to standard liquid.
2) And calculating the clear water average dissolved oxygen value from the underwater depth of the aeration device to the tank surface according to the oxygen content in the gas escaping from the aeration tank.
Specifically, the expression of the average dissolved oxygen value C sm of the clear water from the underwater depth of the aeration device to the pool surface is as follows:
Wherein C SW is saturated dissolved oxygen at the surface of the clean water;
O t is oxygen contained in the gas escaping from the aeration tank;
p b is the absolute pressure at the aeration device.
Further, the expression of oxygen-containing O t in the aeration tank escape gas is:
wherein E A is the oxygen utilization rate of the aeration device.
3) And calculating the oxygen demand in a standard state according to the calculated average dissolved oxygen value C sm and the actual oxygen demand N combined with the dissolved oxygen monitored in the target biochemical pond.
Specifically, the expression of the standard state oxygen demand N o is:
Wherein N is the actual oxygen demand;
C S is saturated dissolved oxygen in clear water under standard conditions;
Alpha is the ratio of the value of the total oxygen transmission coefficient k La in the mixed solution to the value of the total oxygen transmission coefficient k La in the clean water;
beta is the ratio of the saturated dissolved oxygen value in the mixed solution to the saturated dissolved oxygen in the clean water;
C sn is the average dissolved oxygen value of the clear water reaching the pool surface at the underwater depth according to the aeration device;
C O is the residual Dissolved Oxygen (DO) value of the mixed liquor, and T is the temperature of the mixed liquor.
4) And calculating the required gas quantity according to the oxygen utilization rate of the aeration device and the calculated standard state oxygen demand.
Specifically, the calculation process expression of the required air amount G s of each target biochemical pool is as follows:
Wherein G s is the required air quantity;
N O is the standard state oxygen demand;
E A is the oxygen utilization rate of the aeration device.
S3: and (3) opening adjustment is carried out on the electric regulating valve according to the calculated required air quantity, and the air quantity calculation and feedback adjustment are carried out at intervals of rated time.
And the PLC control system adjusts the opening of the electric regulating valve according to the calculated required air quantity, adjusts the electric regulating valve to the required air quantity, and calculates and feeds back and adjusts the air quantity every m seconds (can be set).
In this example, the actual dissolved oxygen value DO a is compared with the set dissolved oxygen low value DO II, dissolved oxygen low value D01, dissolved oxygen high value DO h, and dissolved oxygen high value DO hh every n seconds (can be set).
If the actual dissolved oxygen value is smaller than the set dissolved oxygen low value, namely DO a＜DOll, opening the electric regulating valve; when the opening of the electric regulating valve exceeds the opening upper limit high (which can be set), the blower is turned up until the actual dissolved oxygen value is greater than or equal to the set dissolved oxygen low value, namely DO a≥DOl.
If the actual dissolved oxygen value is larger than the set dissolved oxygen high value, namely DO a＞DOhh, the electric regulating valve is closed; when the opening of the regulating valve is lower than the lower limit low (which can be set), the blower reduces the frequency until the actual dissolved oxygen value is smaller than or equal to the set dissolved oxygen high value DO a≤DOh.
When the frequency of the blower is lower than the lower limit value or the pressure transmitter is higher than the upper limit value, the air release valve on the air line of the aeration pipeline is opened until the frequency of the blower and the outlet pressure of the blower are at normal values.
In the scheme of the embodiment, in the two-stage AO-ABFT process, the influence of the previous aerobic section on the subsequent anoxic section is avoided on the one hand, the carbon reduction denitrification dephosphorization efficiency is improved, and the stable standard of the effluent quality is ensured by monitoring the inflow water flow and simultaneously based on the multiple feedback adjustment of COD, ammonia nitrogen and dissolved oxygen; on the other hand, through the calculation of the aeration control model, real-time accurate aeration is realized, and the operation energy consumption is saved.
Through the application of the system in a sewage station of a certain chemical enterprise for 6 months, the system runs stably, and the stability of the system is enhanced while the water quality of the effluent stably meets the standard of the table 1 of the emission standard of pollutants in petrochemical industry (GB 31571-2015). Compared with the system before application, the energy consumption of the main energy-consuming equipment fan of the system is obviously reduced by 20.5%, and the energy-saving effect is obvious.
It should be understood that the examples are only for illustrating the present application and are not intended to limit the scope of the present application. Furthermore, it should be understood that various changes and modifications can be made by one skilled in the art after reading the teachings of the present application, and such equivalents are intended to fall within the scope of the application as defined in the appended claims.
Claims (10)
1. A two-stage AO-ABFT process aeration control system, comprising:
the anoxic-aerobic tank comprises an anoxic tank and an aerobic tank which are connected in sequence to decompose wastewater;
The aeration biological fluidization pool is connected with the anoxic-aerobic pool and outputs treated water;
The branch extends to the aerobic tank and the aeration biological fluidization tank, and air is input;
The PLC control system is used for receiving monitoring data of each sensor arranged in the anoxic-aerobic tank and the aeration biological fluidization tank and calculating the required air inflow;
the PLC control system receives the state of the electric regulating valve arranged on the aeration pipeline, and adjusts the opening of the electric regulating valve according to the calculated required air inflow.
2. The two-stage AO-ABFT process aeration control system according to claim 1, wherein the anoxic-aerobic tank is a multi-stage anoxic-aerobic tank, and the multi-stage anoxic-aerobic tanks are sequentially connected.
3. A two-stage AO-ABFT process aeration control system according to claim 1 or 2, wherein the sensors arranged in the anoxic tank comprise a COD detector and an ammonia nitrogen detector; the sensor arranged in the aerobic tank is a dissolved oxygen meter; the sensors arranged in the aeration biological fluidization pool comprise a COD detector, an ammonia nitrogen detector and a dissolved oxygen meter.
4. A two-stage AO-ABFT process aeration control system according to claim 1 or 2, wherein said aeration line comprises a main line and a branch line; one end of a branch of the aeration pipeline is connected with a blower, and the other end of the aeration pipeline is emptied; the main way of the aeration pipeline extends a plurality of branches, and the branches of the aeration pipeline are respectively connected with the bottoms of the aerobic tank and the aeration biological fluidization tank.
5. The two-stage AO-ABFT process aeration control system according to claim 4, wherein a pressure transmitter is arranged on one side of the main aeration pipeline close to the blower, and a mobilization adjusting valve is arranged on one side of the main aeration pipeline which is empty; an electric regulating valve and an air flow meter are respectively arranged on the branch of the aeration pipeline.
6. A two-stage AO-ABFT process aeration control system according to claim 1,2 or 5, wherein a water inlet pipe is connected to the top of the anoxic tank, and a water inlet flow meter is arranged on the water inlet pipe.
7. A two-stage AO-ABFT process aeration control method, adopting a two-stage AO-ABFT process aeration control system according to any one of claims 1-6, comprising the steps of:
s1: constructing a two-stage AO-ABFT process aeration control system;
S2: acquiring COD, ammonia nitrogen and dissolved oxygen data of a biochemical combination tank in an aeration control system, and calculating the required air quantity of the biochemical combination tank through an aeration control model;
S3: and (3) opening adjustment is carried out on the electric regulating valve according to the calculated required air quantity, and the air quantity calculation and feedback adjustment are carried out at intervals of rated time.
8. The two-stage AO-ABFT process aeration control method according to claim 7, wherein the aeration control model calculation process is as follows:
1) For the target biochemical pool, calculating the actual oxygen demand by weighting according to the COD difference value and the ammonia nitrogen difference value of the monitored inflow water and the outflow water of the target biochemical pool;
2) Calculating a clear water average dissolved oxygen value from the underwater depth of the aeration device to the tank surface according to the oxygen content in the gas escaping from the aeration tank;
3) Calculating the oxygen demand in a standard state according to the calculated average dissolved oxygen value and the actual oxygen demand and the dissolved oxygen obtained by monitoring in the target biochemical pool;
4) And calculating the required gas quantity according to the oxygen utilization rate of the aeration device and the calculated standard state oxygen demand.
9. The two-stage AO-ABFT process aeration control method according to claim 7 or 8, wherein the biodegradability and inflow rate of mixed liquor in a target biochemical tank are used as weighting coefficients of COD concentration differences, the ratio of the mixed liquor volatile suspended matter concentration MLVSS to the mixed liquor suspended matter concentration MLSS is used as weighting coefficients of total surplus sludge, and the actual oxygen demand is obtained by weighting calculation in combination with the ammonia nitrogen concentration differences between inflow and outflow and the reduced nitrate amount.
10. The two-stage AO-ABFT process aeration control method according to claim 7, wherein the actual dissolved oxygen value is compared with the set dissolved oxygen low value, the set dissolved oxygen high value and the set dissolved oxygen high value every time the rated time, and the opening degree of the electric control valve and the frequency of the blower are adjusted.
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