CN1966426A - Dissolved oxygen control device of Orbal oxidation ditch biological denitrification process and its method - Google Patents
Dissolved oxygen control device of Orbal oxidation ditch biological denitrification process and its method Download PDFInfo
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Abstract
The invention relates to dissolved oxygen controlling device in the Orbal oxidation ditch denitrifying technology as well as the method, which belongs to the activated sludge process intellectually control domain. The traditional constant aerating way in present technologies has poor denitrifying effects and it's a waste of energy. The data signal output interface connects the process controller, the outer ditch aerate meta-frequency controller is installed in the process controller, it is connected to the outer, center and inner ditch meta-frequency air blower through the outlet end of the process controller; the meta-frequency air blower is connected to the outer, center and inner ditch aerating end. The incipient dissolved oxygen value is settled by the active sludge reaction kinetics; the process controller is controlled by the computer, the aerate volume of the air blower is controlled by the meta-frequency controller of the three ditches; when the water quality changes, the aerate volume is regulated according to the conditions and settled regulations of the dissolved oxygen in all the ditches. The nitrogen removal rate is 80% or higher in the invention while the energy consumption can be decreased by 30% or more.
Description
Technical field
Technical field under the present invention is an activated sludge process sewage biological treatment system field of intelligent control.
Background technology
The problem that Orbal oxidation ditch system and denitrification operation thereof exist
1, the Orbal oxidation ditch system is the single mud extended aeration activated sludge process system of a kind of many raceway grooves (being generally three ditches).Sewage and returned sluge enter system by outer raceway groove, enter second pond behind ditch and the septal fossula in flowing through successively.Each raceway groove all is a relatively independent complete mixing system, and mixed solution constantly circulates therein.In typical triple channel system, the dissolved oxygen (DO) of outer fissure, middle ditch and septal fossula generally roughly is controlled between 0～0.5mg/l, 0.5～1.5mg/l and the 2～5mg/l.The step portion cloth of this dissolved oxygen helps save aeration consumption, can create conditions for biological denitrificaion simultaneously.The oxygen condition that loses in the outer fissure has improved the utilization ratio of oxygen supply, and simultaneously lower dissolved oxygen concentration and more rich carbonaceous organic material also provide denitrifying condition.The higher relatively dissolved oxygen concentration of septal fossula can guarantee organic matter removal and nitrification; Middle ditch can be brought into play the effect of " swing " raceway groove, and when the denitrification effect was bad, middle ditch adopted the lower intensified anti-nitrated effect of dissolved oxygen concentration, and when nitrification effect was bad, middle ditch adopted higher dissolved oxygen concentration to strengthen nitrification.The oxidation ditch process system has characteristics such as treatment effect is stable, and operational management is easy, has obtained widespread use in municipal sewage treatment.There is employing oxidation ditch process over half in China in the town sewage plant of founding a capital at present.
2, dissolved oxygen (DO) is controlled at Application of Sewage
Along with the aggravation of China's body eutrophication problem, in the town sewage plant emission standard, strict more to the requirement of water outlet nitrogen.Owing to lack effectively control and ladder of management, cause present many sewage effluents total nitrogen concentrations too high, do not bring into play the power savings advantages and the denitrification functions of oxidation ditch process, even the organic matter degradation that can not bring into normal play and nitrification function.At present, though on-line monitoring instrument such as dissolved oxygen (DO) instrument, redox potential (ORP) instrument and pH instrument have all been installed by many domestic sewage works, but in actual moving process, owing to lack managerial experience and expertise, the method for traditional constant aerating amount of having to still continue to use.The very difficult variation that adapts to water quality and quantity of the operation scheme of constant aerating amount, and according to reaction process adjusting aeration rate, thereby can cause a large amount of energy consumption wastes, and cause the instability that denitrification effect is undesirable and system moves.Not enough and the excessive deterioration that all can cause the mud living environment of oxygen in the aeration tank causes that treatment effect descends and causes the unsteady running of system: when oxygen is not enough, on the one hand since in the aeration tank thread fungus can breed in a large number, finally produce sludge bulking; Growth velocity owing to other bacteriums reduces the effluent quality decline that causes on the other hand.Cause suspended solids settleability variation when oxygen excessive (being excessive aeration) then can cause owing to the active sludge flco is destroyed, make aeration energy consumption too high simultaneously.
Summary of the invention
Know-why
The efficient denitrification process that realizes the Orbal oxidation ditch just is: at the outer raceway groove that denitrification mainly takes place, realize maximum ammonia nitrogen oxidation (nitrifying process) and nitric nitrogen removal (denitrification process).But the nitrification and denitrification process is the process of mutually promoting on the one hand, has only higher nitration reaction, could provide competent reaction substrate for anti-nitration reaction; On the other hand, two reactions are for the requirement difference of reaction conditions: the nitrifying process of ammonia nitrogen oxidation is the process that needs oxygen to participate in, and requires certain dissolved oxygen concentration in the system; And the denitrification process that nitric nitrogen is removed is not need oxygen, and along with the raising of dissolved oxygen concentration, denitrification process can be suppressed even stop fully.Therefore, determine suitable dissolved oxygen, make the outer fissure of Orbal oxidation ditch nitrated, especially denitrification process can reach maximum speed of reaction, and realizes farthest total nitrogen removal in the outer raceway groove, is the key of this denitrification system design.
Among the present invention, by the dynamic (dynamical) calculating of existing activated sludge reaction, and in conjunction with a large amount of actual operating data, analyzed the relation of the changing conditions of ammonia nitrogen, nitric nitrogen and nitrite nitrogen concentration in the outer raceway groove with dissolved oxygen concentration, discovery can reach both optimum combination of nitrification and denitrification process under specific dissolved oxygen value condition, make the total nitrogen concentration value in the outer raceway groove reach minimum value, as shown in Figure 1:
Dissolved oxygen less than a certain specific range of values in, increase along with dissolved oxygen, the ammonia nitrogen oxygenizement constantly strengthens, ammonia nitrogen concentration constantly reduces, and nitric nitrogen concentration increase simultaneously is not obvious, illustrates in this lower dissolved oxygen scope, nitrification effect is in the process of strengthening, the denitrification effect is not subjected to the influence that dissolved oxygen increases, and total nitrogen (in municipal effluent and sanitary sewage, total nitrogen mainly exists with ammonia nitrogen and two kinds of forms of nitric nitrogen) is removed and constantly strengthened; And at the unique point place, this moment, total nitrogen concentration touched the bottom, illustrate that total nitrogen has been issued to maximum removal effect at this dissolved oxygen conditions, then Ci Shi dissolved oxygen value is an optimum setting value (denitrification of outer raceway groove is the key of system's denitrification operation, and nitrification can be guaranteed in middle raceway groove and interior raceway groove) in the outer raceway groove; After unique point, along with the increase of dissolved oxygen concentration, nitrification effect is further strengthened, and ammonia nitrogen concentration further reduces; But denitrification effect rapid deterioration, nitric nitrogen concentration constantly raises, and shows on the total nitrogen to be exactly that the total nitrogen value constantly raises.In continuous-flow system, under the suitable situation of operational conditions, the concentration of nitrite nitrogen remains very low.
Though the dissolved oxygen concentration value of outer raceway groove the best is subjected to entering organic matter of water concentration, nitrogen concentration of element and reactor characteristic, as hydraulic detention time, sludge concentration, influence such as sludge age and return sludge ratio, but objectively there is a dissolved oxygen value, under this dissolved oxygen conditions, the total nitrogen value that can realize outer raceway groove is for minimum.
Because middle raceway groove and the higher dissolved oxygen concentration of interior raceway groove, lack the carbon source that needs in the denitrification process simultaneously,, but control its dissolved oxygen concentration within the specific limits so the effect in system's denitrogenation is limited, can guarantee under the normal operation prerequisite of system save aeration consumption.
Technical scheme
A kind of dissolved oxygen control device of Orbal oxidation ditch biological denitrification process, comprise water tank inlet A, the Orbal oxidation ditch B of concentric triple channel arranged in series, settling tank C and computer control system D four most of form (referring to accompanying drawings 2), water inlet connects intake pump successively by water tank A, is connected the outer raceway groove 4 of Orbal oxidation ditch B with water-in 3 through water inlet pipe 2; Outside, in, establish aeration head in the interior raceway groove, the plug-flow pump, agitator, interior raceway groove connects settling tank C;
It is characterized in that: the data signal output interface 34 of computer links to each other through the input terminus 36 of lead connection procedure controller 35, outer fissure aeration frequency-variable controller 37, middle ditch aeration frequency-variable controller 38 and septal fossula aeration frequency-variable controller 39 are set in the process controller 35, by the output terminal 40 of process controller, be connected with outer raceway groove frequency conversion gas blower 41, middle raceway groove frequency conversion gas blower 42 and interior raceway groove frequency conversion gas blower 43 respectively; Outer raceway groove frequency conversion gas blower 41, middle raceway groove frequency conversion gas blower 42 and interior raceway groove frequency conversion gas blower 43 link to each other with interior raceway groove aeration head 16 with outer raceway groove aeration head 5, middle raceway groove aeration head 11 respectively by outer raceway groove aeration tube 44, middle raceway groove aeration tube 45 and interior raceway groove aeration tube 46.
The invention provides a kind of dissolved oxygen control method of Orbal oxidation ditch biological denitrification process, it is characterized in that, may further comprise the steps:
1) start intake pump and intake continuously, start aeration blower to the triple channel aeration, start agitator and stir, startup plug-flow pump promotes mixed solution and circulates; Start sludge reflux pump continuous backflow second pond mud.
2) according to the influent quality situation of analyzing, by existing activated sludge reaction dynamics calculation, simultaneously in conjunction with the dissolved oxygen set(ting)value under the definite corresponding water inlet condition of a large amount of experiments, set the dissolved oxygen initial value of initial outer raceway groove, middle raceway groove and interior raceway groove, set(ting)value is given process controller by computer output control signal, and process controller is by the aeration rate of the aeration frequency-variable controller difference control of conversion gas blower of triple channel;
Outer raceway groove dissolved oxygen set(ting)value DOref1: getting and making total nitrogen concentration value in the outer raceway groove is that dissolved oxygen concentration under minimum value (the unique point place as shown in Figure 1) condition is (because the existence of dissolved oxygen is for the strongly inhibited effect of denitrification process, so the scope of outer raceway groove dissolved oxygen is generally all 0～0.4mg/l); Middle raceway groove dissolved oxygen set(ting)value DOref2: get and make the dissolved oxygen concentration of the interior ammonia nitrogen concentration of middle raceway groove less than the minimum of 8.0mg/l; The interior ammonia nitrogen concentration of raceway groove was less than the dissolved oxygen concentration of the minimum of 1.0mg/l in interior raceway groove dissolved oxygen set(ting)value DOref3 got and makes.(it is that ammonia nitrogen concentration is less than 100mg/l in raw waste water that middle raceway groove ammonia nitrogen concentration imposes a condition less than the concentration value of 1.0mg/l less than 8mg/l and interior raceway groove ammonia nitrogen concentration.When handling the higher sewage of ammonia nitrogen concentration,, determine the ammonia nitrogen set(ting)value in the raceway groove and interior raceway groove in the control corresponding rule because of ammonia nitrogen emission standard according to this sewage.)
More than these data all can adjust, and the adjustment technology scheme is those skilled in the art's known technology general knowledge.So in principle scope of the present invention, the data adjustment to technical scheme should be considered as not breaking away from protection scope of the present invention.
3) read the signal of the dissolved oxygen in each raceway groove, as the real-time controlled variable of process of Orbal oxidation ditch denitrification process; When influent quality changes and the constant situation of aeration rate, the dissolved oxygen values in three raceway grooves can change, when one of following condition takes place, computer sends instruction, by process controller control aeration frequency-variable controller, change the discharge quantity of fan of frequency conversion gas blower, realize adjusting for aeration rate.
A. the control condition for outer raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref1 and dissolved oxygen measured value DO1 is greater than 0.1mg/l, and the time length was greater than 30 minutes; 2. outer raceway groove dissolved oxygen measured value DO1 is less than the lower limit set value of outer raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO1 is greater than the upper limit set value of outer raceway groove dissolved oxygen, and the time length was greater than 15 minutes;
B. the control condition for middle raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref2 and dissolved oxygen measured value DO2 is greater than 0.2mg/l, and the time length was greater than 30 minutes; 2. middle raceway groove dissolved oxygen measured value DO2 is less than the lower limit set value of middle raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO2 is greater than the upper limit set value of middle raceway groove dissolved oxygen, and the time length was greater than 15 minutes;
C. the control condition for interior raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref3 and dissolved oxygen measured value DO3 is greater than 0.5mg/l, and the time length was greater than 30 minutes; 2. interior raceway groove dissolved oxygen measured value DO3 is less than the lower limit set value of interior raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO3 is greater than the upper limit set value of interior raceway groove dissolved oxygen, and the time length was greater than 15 minutes.
The formulation of control law is in line with timely, reliable and workable principle, consider suitable controlling reaction time, avoid in the short period of time because the sum of errors of dissolved oxygen on-line determination instrument is disturbed the inaccurate of the measurement signal that causes, and cause the generation of the situation of frequent change aeration rate; Consider that simultaneously aeration rate changes the feasibility of frequency in engineering.
When the Orbal oxidation ditch is used to handle trade effluent, the dissolved oxygen control method of above denitrification process stands good, but concrete set(ting)value, need be in conjunction with the operating parameter of sewage quality and model, the particular case concrete analysis, comprehensively determine best control condition by dynamics calculation, as the ammonia nitrogen controlling concn of each raceway groove etc.
Adopt online dissolved oxygen (DO) concentration as controlled variable, mainly contain following some reason: (1) feasibility, DO transmitter and PLC Controlling System have all been installed by present many municipal sewage plants, have the objective condition of realization; (2) dependency, a large amount of research at present shows that DO concentration is tight with the organic matter degradation in the sewage disposal, nitrification and denitrification procedure relation; (3) DO concentration on-line sensor has characteristics such as time of response weak point and precision height; (4) good reliability, because DO concentration is one of of paramount importance operating parameter that influences sewage biological treatment system, DO control can guarantee the normal operation of Sludge System within the specific limits; Simultaneously with develop at present can the on-line determination organism, the transmitter of nitrogen, phosphorus compares, that the DO transmitter has is cheap, maintenance cost is low and stable strong, can be easily and characteristics such as computer interface.
Along with popularizing day by day and widespread use of oxidation ditch process, Orbal oxidation ditch biological denitrification and energy-saving run system based on dissolved oxygen control, can change control aeration rate in real time according to the raw water quality water yield, not only the nitric efficiency that can avoid traditional control method to cause is low, high and the unsettled shortcoming of operational system of energy consumption, improve nitric efficiency and reduce operation energy consumption, and important significance for theories and using value are arranged for further realization and the On-line Fuzzy control of enriching activated sludge process.
The dissolved oxygen control method of Orbal oxidation ditch of the present invention is compared with permanent aeration rate or permanent dissolved oxygen control method that existing Orbal oxidation ditch is commonly used, has the following advantages:
(1) energy-saving effect is obvious: can make aeration rate as far as possible consistent with the oxygen requirement of microorganism, avoided that aeration not exclusively causes nitrated not exclusively and organic matter degradation not thorough, mud expands; And unsteady running state such as the microorganism flco of excessive energy wastage that causes of aeration and system is destructurized.Compare with traditional constant aerating amount, can save aeration consumption more than 30%.
(2) denitrification effect is good: on the basis of the present invention's raceway groove denitrification potentiality outside giving full play to, add outside not under the situation of denitrifying carbon source, only utilize the carbon source in the former water to carry out denitrification, the denitrification effect obviously improves.And the general denitrification of only considering for outer raceway groove of the denitrogenation of Orbal oxidation ditch control is at present considered not enough for the strengthened denitrification effect of middle raceway groove and the energy-conserving action of interior raceway groove.Under the competent condition of carbon source, can realize the nitrogen removal rate more than 80% in former water, the water outlet ammonia nitrogen is less than 1mg/l, and total nitrogen is less than 10mg/l.
(3) nitrification and denitrification occurs in the same reactor, with present order nitrated-denitrification process compares, and has process simplification, saves the energy expenditure of nitrification liquid internal reflux; Do not add outer carbon source, make full use of in the raw waste water organism, save carbon source and add advantages such as operating process and expense input as denitrifying carbon source.
Description of drawings
Fig. 1 is in the outer raceway groove dissolved oxygen change procedure, the changing conditions of ammonia nitrogen, nitric nitrogen, nitrite nitrogen and total nitrogen in the outer raceway groove;
Fig. 2 is this experimental installation structural representation;
1 intake pump; 2 water inlet pipes; 3 water-ins; 4 outer raceway grooves; 5 outer raceway groove aeration heads; 6 outer raceway groove plug-flow pumps; 7 outer raceway groove agitators; 8 perforated retainers; Raceway groove in 9; The connected entrance of 10 outer raceway grooves and middle raceway groove; Raceway groove aeration head in 11; Raceway groove agitator in 12; Raceway groove plug-flow pump in 13; Raceway groove in 14; The connected entrance of raceway groove and interior raceway groove in 15; Raceway groove aeration head in 16; Raceway groove plug-flow pump in 17; 18 septal fossula agitators; 19 water outlets; 20 oxidation ditch rising pipes; 21 settling tank rising pipes; 22 sludge reflux pumps; 23 mud return lines; 24 mud refluxing openings; 25 sludge from sedimentation tank pipes; 26 outer raceway groove dissolved oxygen sensors; Raceway groove dissolved oxygen sensor in 27; Raceway groove dissolved oxygen sensor in 28; 29 outer fissure dissolved oxygen meters; Ditch dissolved oxygen meter in 30; 31 septal fossula dissolved oxygen meters; 32 computers; The data signal input interface of 33 computers; The data signal output interface of 34 computers; 35 process controllers; The input terminus of 36 process controllers; 37 outer fissure aeration frequency-variable controllers; Ditch aeration frequency-variable controller in 38; 39 septal fossula aeration frequency-variable controllers; The output terminal of 40 process controllers; 41 outer raceway groove frequency conversion gas blowers; Raceway groove frequency conversion gas blower in 42; Raceway groove frequency conversion gas blower in 43; 44 outer fissure aeration tubes; Ditch aeration tube in 45; 46 septal fossula aeration tubes
Fig. 3 is the real-time control flow chart of Orbal oxidation ditch biological denitrification dissolved oxygen control device of the present invention and method.
Fig. 4 is a treatment effect of using Orbal oxidation ditch biological denitrification dissolved oxygen control method Treating Municipal Sewage of the present invention.
Fig. 5 uses the treatment effect that Orbal oxidation ditch biological denitrification dissolved oxygen control method of the present invention is handled the low ratio of carbon to ammonium sanitary sewage.
Embodiment
In conjunction with the embodiments, the concrete operations of technology of the present invention operation operation is as follows:
Embodiment 1: certain city's municipal sewage treatment
Experimental water is the aerated grit chamber water outlet of municipal sewage plant, North China, and its representative water quality is mainly: COD210～400mg/l, average 288mg/l; BOD
5130～210mg/l, average is 147mg/l, NH
4 +-N15～46mg/l, average is 29mg/l, and total nitrogen (TN) mainly is made up of ammonia nitrogen, and average is 29.5mg/l.Every day sampling analysis once, the analytical procedure that adopts in the test all is standard methods of State Bureau of Environmental Protection issue.
Trial model: the useful volume of Orbal oxidation ditch is made as 330L, outer raceway groove, and the volume of middle raceway groove and interior raceway groove is respectively 180L, 85L and 65L; The reactor sludge concentration is 3500mg/l, and sludge age is about 25 days, and temperature of reaction is 28 ℃; The mud quantity of reflux is 80% of a flooding velocity, water tank inlet 300L, and second pond useful volume 100L, the continuous water-inlet continuous water-outlet of model, the hydraulic detention time of Orbal oxidation ditch are 14 hours.
The experimental installation of the Orbal oxidation ditch biological denitrification dissolved oxygen control method that design is used among the present invention, by constituting with lower section and operational process:
By water tank inlet A, the Orbal oxidation ditch B of concentric triple channel arranged in series, second pond C and computer control system D four most of form (referring to accompanying drawings 2).Through intake pump 1 effect, process water inlet pipe 2 and water-in 3 enter the outer raceway groove 4 of Orbal oxidation ditch B continuously by water tank A in water inlet.
Raceway groove is through the aeration effect generation organic matter removal and the ammonia nitrogen oxidizing reaction of aeration head 5 outside, simultaneously mixed solution under the effect of plug-flow pump 6 outside raceway groove circulate, in the denitrification of non-aeration point generation nitric nitrogen.Raceway groove is provided with agitator 7 outside, and the enhancing mixed effect also prevents sludge settling.
Outer raceway groove mixed solution enters middle raceway groove 9 through after reacting through connected entrance 10 run by gravitys that are arranged on partition wall bottom between outer raceway groove 4 and the middle raceway groove 9.Under the middle raceway groove pushing effect through the aeration of aeration head 11 and middle raceway groove plug-flow pump 13 organic matter degradation, nitrated/processes such as denitrification takes place, and mixed solution is flowed at middle raceway groove internal recycle.Middle raceway groove is provided with agitator 12 enhancing mixed effects and prevents sludge settling.
Middle raceway groove mixed solution enters septal fossula 14 through after reacting through connected entrance 15 run by gravitys bottom the partition wall between raceway groove 9 in being arranged on and the interior raceway groove 14.Main generation organism and nitration reaction under the effect of interior raceway groove aeration head 16 and septal fossula plug-flow pump 17, and mixed solution is circulated at interior raceway groove.Interior raceway groove is provided with agitator 18 enhancing mixed effects and prevents sludge settling.
The mixed solution of interior raceway groove enters settling tank C through after reacting through water outlet 19 and oxidation ditch rising pipe 20 run by gravitys that are provided with in the interior raceway groove 14.After the solid-liquid separation of mixed solution through settling tank C, supernatant liquor is through 21 dischargings of settling tank rising pipe; Part mud is back to outer raceway groove 4 through sludge reflux pump 22 and mud return line 23 through the mud refluxing opening 24 on the oxidation ditch.Part mud is through the shore pipe 25 discharge systems of settling tank C.
Effect and operability for the dissolved oxygen control method of verifying the Orbal oxidation ditch biological denitrification that proposes among the present invention, designed a cover reactor, the reactor features of model engineering oxidation ditch, only be with the difference of using on the engineering, experimental model is provided with the baffle plate 8 of perforation at outer fissure, with the Control Circulation flow velocity, simulate the circulating fluidized of oxidation ditch better.
In conjunction with the accompanying drawings 2 and accompanying drawing 3, concrete control process of the present invention is as follows:
1, use Orbal oxidation ditch biological denitrification dissolved oxygen Controlling System provided by the present invention and device, at first open intake pump, to the outer raceway groove water inlet of Orbal oxidation ditch, per hour flooding quantity is 23.6L/h continuously; Detect influent quality, determine aeration rate according to influent quality in the certain hour, the aerator that starts triple channel begins aeration, and pressurized air is discharged in the reactor with the form of microbubble, fully contacts with the mixed solution of sewage with active sludge; The whipping device and the plug-flow equipment that start in the triple channel stir and plug-flow.Open sludge reflux pump backflow second pond mud.Realize the continuous operation of this system and reach steady state.
2, according to the activated sludge reaction dynamics calculation, a large amount of actual operating data of association reaction device, analyze the organic concentration between each raceway groove, the variation of ammonia nitrogen and nitric nitrogen concentration is determined at this operational conditions and this water quality scope (representative value: COD average 288mg/l with the relation of dissolved oxygen concentration in the corresponding raceway groove; BOD
5Average is 147mg/l, NH
4 +-N average is 29mg/l, and the total nitrogen average is 29.5mg/l) in, the dissolved oxygen concentration value that reaches the total nitrogen concentration appearance point of minimum in the outer raceway groove is 0.30mg/l; Raceway groove is guaranteed the 0.8mg/l that is less than the minimum dissolved oxygen concentration of 8mg/l of ammonia nitrogen concentration in the raceway groove in determining; Raceway groove guarantees that the interior ammonia nitrogen concentration of raceway groove is 1.2mg/l less than the minimum dissolved oxygen concentration of 1mg/l in determining.Based on the aeration rate control law of above-mentioned dissolved oxygen value setting based on the dissolved oxygen concentration value.(organic concentration does not become the restricted condition of water outlet with this understanding, and water outlet remains on below the 50mg/l substantially.)
3, start computer, the start-up course real-time control system, begin to detect the dissolved oxygen value in the triple channel, and according to the absolute difference of set(ting)value and detected value, and the setting restriction of dissolved oxygen and change condition are sent instruction for the aeration frequency-variable controller, change the rotating speed of (increase or reduce) frequency conversion fan, thereby change aeration rate, when satisfying one of following condition in each raceway groove, carry out and change according to the variation of dissolved oxygen:
A. the control condition for outer raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO1 and dissolved oxygen set(ting)value DOref1 (0.3mg/l) is greater than 0.1mg/l, and the time length was greater than 30 minutes; 2. outer raceway groove dissolved oxygen measured value DO1 is less than 0.1mg/l, and the time length was greater than 15 minutes; 3. outer raceway groove dissolved oxygen measured value DO1 is greater than 0.5mg/l, and the time length was greater than 15 minutes;
B. the control condition for middle raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO2 and dissolved oxygen set(ting)value DOref2 (0.8mg/l) is greater than 0.2mg/l, and the time length was greater than 30 minutes; 2. middle raceway groove dissolved oxygen measured value DO2 is less than 0.5mg/l, and the time length was greater than 15 minutes; 3. middle raceway groove dissolved oxygen measured value DO2 is greater than 2.0mg/l, and the time length was greater than 15 minutes;
C. the control condition for interior raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO3 and dissolved oxygen set(ting)value DOref3 (1.5mg/l) is greater than 0.5mg/l, and the time length was greater than 30 minutes; 2. interior raceway groove dissolved oxygen measured value DO3 is less than 0.5mg/l, and the time length was greater than 15 minutes; 3. interior raceway groove dissolved oxygen measured value DO3 is greater than 3.0mg/l, and the time length was greater than 15 minutes.
4, regularly detect the variation of water of water inlet, monitor the changing conditions of dissolved oxygen in each raceway groove in real time, mediate for aeration rate.
When satisfying above-mentioned control condition, carry out online adjusting control for the aeration rate of different raceway grooves.
Experimental result shows that referring to accompanying drawing 4 municipal sewage treatment effects, the total nitrogen removal effect improves greatly, and the total nitrogen average removal rate is 74%, and the water outlet ammonia nitrogen concentration remains on below the 0.5mg/l, and the water outlet total nitrogen is below 10mg/l.Outer raceway groove, the dissolved oxygen of middle raceway groove and interior raceway groove are controlled at 0.3mg/l respectively under typical condition of water quality, 0.8mg/l and 1.2mg/l greatly reduce the aeration energy consumption of system.
Embodiment 2: the processing of certain biotope low ratio of carbon to ammonium sanitary sewage
Sanitary sewage in the septic tank of experimental water biotope, water quality characteristics is that carbon-nitrogen ratio is low, its representative water quality is mainly: COD160～310mg/l, average 220mg/l; BOD
5100～165mg/l, average is 115mg/l, NH
4 +-N58～108mg/l, average is 80mg/l, and total nitrogen (TN) 59～110mg/l mainly is made up of ammonia nitrogen, and average is 81mg/l, and its carbon-nitrogen ratio (COD/TN) has only 2.75.Every day sampling analysis once, the analytical procedure that adopts in the test all is standard methods of State Bureau of Environmental Protection issue.
Trial model: the useful volume of Orbal oxidation ditch is made as 330L, outer raceway groove, and the volume of middle raceway groove and interior raceway groove is respectively 180L, 85L and 65L; The reactor sludge concentration is 5000mg/l, and sludge age is about 30 days, and temperature of reaction is 28 ℃; The mud quantity of reflux is 150% of a flooding velocity, water tank inlet 300L, and second pond useful volume 100L, the continuous water-inlet continuous water-outlet of model, the hydraulic detention time of Orbal oxidation ditch are 16.5 hours.Above-mentioned working condition and design variable mainly are according to the low water quality characteristics of water inlet carbon-nitrogen ratio, and on the basis of a large amount of experiments, the association reaction dynamics calculation determines that major measure is to improve sludge concentration, increases return sludge ratio and prolongs hydraulic detention time.
Experimental installation and operational process are as described in a kind of the above-mentioned real-time mode.
In conjunction with the accompanying drawings 2 and accompanying drawing 3, concrete control process of the present invention is as follows:
1, use Orbal oxidation ditch biological denitrification dissolved oxygen Controlling System provided by the present invention and device, at first open intake pump, to the outer raceway groove water inlet of Orbal oxidation ditch, per hour flooding quantity is 20.0L/h continuously; Detect influent quality, determine aeration rate according to influent quality in the certain hour, the aerator that starts triple channel begins aeration, and pressurized air is discharged in the reactor with the form of microbubble, fully contacts with the mixed solution of sewage with active sludge; The whipping device and the plug-flow equipment that start in the triple channel stir and plug-flow.Open sludge reflux pump backflow second pond mud.Realize the continuous operation of this system and reach steady state.
2, according to the activated sludge reaction dynamics calculation, a large amount of actual operating data of association reaction device, analyze the organic concentration between each raceway groove, the variation of ammonia nitrogen and nitric nitrogen concentration determines that with the relation of dissolved oxygen concentration in the corresponding raceway groove (representative value is COD average 220mg/l with this water quality scope in this operation condition condition; The BOD5 average is 115mg/l, NH
4 +-N average is 80mg/l, and the total nitrogen average is 81mg/l) in, the dissolved oxygen concentration value that reaches the total nitrogen concentration appearance point of minimum in the outer raceway groove is 0.10mg/l; Raceway groove is guaranteed the 0.5mg/l that is less than the minimum dissolved oxygen concentration of 8mg/l of ammonia nitrogen concentration in the raceway groove in determining; Raceway groove guarantees that the interior ammonia nitrogen concentration of raceway groove is 0.8mg/l less than the minimum dissolved oxygen concentration of 2mg/l (under this experiment condition, in order to improve denitrification effect, the limit value that suitably improves the water outlet ammonia nitrogen concentration is 2mg/l) in determining.Based on the aeration rate control law of above-mentioned dissolved oxygen value setting based on the dissolved oxygen concentration value.(under this condition of water quality, organic matter removal does not become the restricted condition of water outlet, and the removal of total nitrogen is subjected to the into restriction of water organic carbon source shortage, so the carbon source that whether can make full use of in the former water is the key of denitrogenation.)
3, start computer, the start-up course real-time control system, begin to detect the dissolved oxygen value in the triple channel, and according to the absolute difference of set(ting)value and detected value, and the setting restriction of dissolved oxygen and change condition are sent instruction for the aeration frequency-variable controller, change the rotating speed of (increase or reduce) frequency conversion fan, thereby change aeration rate according to the variation of dissolved oxygen, when satisfying one of following condition in each raceway groove:
A. the control condition for outer raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO1 and dissolved oxygen set(ting)value DOref1 (0.1mg/l) is greater than 0.05mg/l, and the time length was greater than 30 minutes; 2. outer raceway groove dissolved oxygen measured value DO1 is less than 0.02mg/l, and the time length was greater than 15 minutes; 3. outer raceway groove dissolved oxygen measured value DO1 is greater than 0.2mg/l, and the time length was greater than 15 minutes;
B. the control condition for middle raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO2 and dissolved oxygen set(ting)value DOref2 (0.5mg/l) is greater than 0.2mg/l, and the time length was greater than 30 minutes; 2. middle raceway groove dissolved oxygen measured value DO2 is less than 0.2mg/l, and the time length was greater than 15 minutes; 3. middle raceway groove dissolved oxygen measured value DO2 is greater than 0.8mg/l, and the time length was greater than 15 minutes;
C. the control condition for interior raceway groove is: when 1. the absolute value of the difference of dissolved oxygen measured value DO3 and dissolved oxygen set(ting)value DOref3 (0.8mg/l) is greater than 0.3mg/l, and the time length was greater than 30 minutes; 2. interior raceway groove dissolved oxygen measured value DO3 is less than 0.4mg/l, and the time length was greater than 15 minutes; 3. interior raceway groove dissolved oxygen measured value DO3 is greater than 1.2mg/l, and the time length was greater than 15 minutes.
4, regularly detect the variation of water of water inlet, monitor the changing conditions of dissolved oxygen in each raceway groove in real time, mediate for aeration rate.
Experimental result shows, referring to accompanying drawing 5, use dissolved oxygen Controlling System of the present invention, control low-down dissolved oxygen by outer raceway groove, denitrification in conjunction with raceway groove in strengthening, and the restriction aeration of interior raceway groove, effectively utilize limited water-inlet carbon source and carried out denitrification denitrogenation, nitrogen removal rate on average reaches 71%, and by improving sludge concentration, increase measures such as return sludge ratio and prolongation hydraulic detention time, still guaranteed good nitrated effect under lower dissolved oxygen conditions, the water outlet ammonia nitrogen concentration is below 2mg/l.
Though carbon source deficiency in the former water, by the control dissolved oxygen, the carbon source that has made full use of in the former water is carried out denitrification; The denitrification potentiality of raceway groove are the keys that system obtains higher nitric efficiency in giving full play to.In conjunction with higher sludge concentration, return sludge ratio and long means such as hydraulic detention time, add outside not under the condition of carbon source simultaneously, the concentration of water outlet total nitrogen is controlled at about 20mg/l.
Claims (2)
1, a kind of dissolved oxygen control device of Orbal oxidation ditch biological denitrification process, comprise water tank inlet (A), the Orbal oxidation ditch (B) of concentric triple channel arranged in series, settling tank (C) and computer control system (D) four major parts, water inlet connects intake pump successively by water tank (A), is connected the outer raceway groove (4) of Orbal oxidation ditch B with water-in (3) through water inlet pipe (2); Outside, in, establish aeration head in the interior raceway groove, the plug-flow pump, agitator, interior raceway groove connects settling tank (C);
Outer raceway groove (4) in Orbal oxidation ditch reactor B, in middle raceway groove (9) and the interior raceway groove (14) outer raceway groove dissolved oxygen sensor (26) is set respectively, middle raceway groove dissolved oxygen sensor (27) and interior raceway groove dissolved oxygen sensor (28), the sensor respectively by lead with outer fissure dissolved oxygen meter (29), middle ditch dissolved oxygen meter (30) with after septal fossula dissolved oxygen meter (31) is connected, be connected with the data signal input interface (33) of computer (32);
It is characterized in that: the data signal output interface (34) of computer links to each other through the input terminus (36) of lead connection procedure controller (35), outer fissure aeration frequency-variable controller (37), middle ditch aeration frequency-variable controller (38) and septal fossula aeration frequency-variable controller (39) are set in the process controller (35), by the output terminal (40) of process controller, be connected with outer raceway groove frequency conversion gas blower (41), middle raceway groove frequency conversion gas blower (42) and interior raceway groove frequency conversion gas blower (43) respectively; Outer raceway groove frequency conversion gas blower (41), middle raceway groove frequency conversion gas blower (42) and interior raceway groove frequency conversion gas blower (43) link to each other with interior raceway groove aeration head (16) with outer raceway groove aeration head (5), middle raceway groove aeration head (11) respectively by outer raceway groove aeration tube (44), middle raceway groove aeration tube (45) and interior raceway groove aeration tube (46).
2, a kind of dissolved oxygen control method of Orbal oxidation ditch biological denitrification process is characterized in that, may further comprise the steps:
1) start intake pump and intake continuously, start aeration blower to the triple channel aeration, start agitator and stir, startup plug-flow pump promotes mixed solution and circulates; Start sludge reflux pump continuous backflow second pond mud;
2) according to the influent quality situation of analyzing, by existing activated sludge reaction dynamics calculation, simultaneously in conjunction with the dissolved oxygen set(ting)value under the definite corresponding water inlet condition of a large amount of experiments, set the dissolved oxygen initial value of initial outer raceway groove, middle raceway groove and interior raceway groove, set(ting)value is given process controller by computer output control signal, and process controller is by the aeration rate of the aeration frequency-variable controller difference control of conversion gas blower of triple channel;
Outer raceway groove dissolved oxygen set(ting)value DOref1: getting and making total nitrogen concentration value in the outer raceway groove is dissolved oxygen concentration under the minimum conditions; Middle raceway groove dissolved oxygen set(ting)value DOref2: get and make the dissolved oxygen concentration of the interior ammonia nitrogen concentration of middle raceway groove less than the minimum of 8.0mg/l; The interior ammonia nitrogen concentration of raceway groove was less than the dissolved oxygen concentration of the minimum of 1.0mg/l in interior raceway groove dissolved oxygen set(ting)value DOref3 got and makes;
3) read the signal of the dissolved oxygen in each raceway groove, as the real-time controlled variable of process of Orbal oxidation ditch denitrification process; When influent quality changes and the constant situation of aeration rate, the dissolved oxygen values in three raceway grooves can change, when one of following condition takes place, computer sends instruction, by process controller control aeration frequency-variable controller, change the discharge quantity of fan of frequency conversion gas blower, realize adjusting for aeration rate;
A. the control condition for outer raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref1 and dissolved oxygen measured value DO1 is greater than 0.1mg/l, and the time length was greater than 30 minutes; 2. outer raceway groove dissolved oxygen measured value DO1 is less than the lower limit set value of outer raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO1 is greater than the upper limit set value of outer raceway groove dissolved oxygen, and the time length was greater than 15 minutes;
B. the control condition for middle raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref2 and dissolved oxygen measured value DO2 is greater than 0.2mg/l, and the time length was greater than 30 minutes; 2. middle raceway groove dissolved oxygen measured value DO2 is less than the lower limit set value of middle raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO2 is greater than the upper limit set value of middle raceway groove dissolved oxygen, and the time length was greater than 15 minutes;
C. the control condition for interior raceway groove is: when 1. the absolute value of the difference of dissolved oxygen set(ting)value DOref3 and dissolved oxygen measured value DO3 is greater than 0.5mg/l, and the time length was greater than 30 minutes; 2. interior raceway groove dissolved oxygen measured value DO3 is less than the lower limit set value of interior raceway groove dissolved oxygen, and the time length was greater than 15 minutes; 3. dissolved oxygen measured value DO3 is greater than the upper limit set value of interior raceway groove dissolved oxygen, and the time length was greater than 15 minutes.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102815789A (en) * | 2012-09-19 | 2012-12-12 | 陕西科技大学 | Oxidation ditch and denitrification operation method thereof |
| CN106527332A (en) * | 2016-11-05 | 2017-03-22 | 杭州裕达自动化科技有限公司 | Precise control system for dissolved oxygen |
| CN108958033A (en) * | 2018-07-27 | 2018-12-07 | 南宁学院 | A kind of municipal sewage Air Exposure intelligent control method |
| CN113651417A (en) * | 2021-08-27 | 2021-11-16 | 艾萍 | Sewage treatment system and method for environmental engineering |
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| US3990974A (en) * | 1975-08-06 | 1976-11-09 | Canton Textile Mills, Inc. | Waste treatment and solids separating system |
| US4159243A (en) * | 1977-08-09 | 1979-06-26 | Envirotech Corporation | Process and system for controlling an orbital system |
| CN1110962A (en) * | 1994-04-26 | 1995-11-01 | 机械电子工业部机械工业环境保护技术研究所 | Blast aeration automatic control system |
| CN1313250A (en) * | 2000-03-10 | 2001-09-19 | 中国林业科学研究院林产化学工业研究所 | Dynamic aeration process for treating sewage with high efficiency and low energy consumption |
| CN1154615C (en) * | 2000-09-22 | 2004-06-23 | 北京中环康裕环保工程技术有限公司 | Automatic controller for sewage treatment process |
| CN201033748Y (en) * | 2006-11-21 | 2008-03-12 | 北京工业大学 | Dissolved oxygen controlling means for Orbal oxidation ditch biological denitrification process |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102815789A (en) * | 2012-09-19 | 2012-12-12 | 陕西科技大学 | Oxidation ditch and denitrification operation method thereof |
| CN106527332A (en) * | 2016-11-05 | 2017-03-22 | 杭州裕达自动化科技有限公司 | Precise control system for dissolved oxygen |
| CN108958033A (en) * | 2018-07-27 | 2018-12-07 | 南宁学院 | A kind of municipal sewage Air Exposure intelligent control method |
| CN113651417A (en) * | 2021-08-27 | 2021-11-16 | 艾萍 | Sewage treatment system and method for environmental engineering |
| CN113651417B (en) * | 2021-08-27 | 2022-07-15 | 昆山皖源环境技术有限公司 | Sewage treatment system and method for environmental engineering |
| CN116621326A (en) * | 2023-03-14 | 2023-08-22 | 北京城市排水集团有限责任公司 | Simplified calculation method for volume and residence time of oxidation ditch process functional area |
| CN116621326B (en) * | 2023-03-14 | 2024-01-02 | 北京城市排水集团有限责任公司 | Simplified calculation method for volume and residence time of oxidation ditch process functional area |
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