The control method of A/O biological denitrification reactor, nitrifying process and On-line Fuzzy control device thereof, method
Technical field
The present invention relates to a kind of sewage treatment process and control device thereof and method, the nitrated apparatus and method of particularly a kind of Continuous Flow biological denitrification process and intelligence controlling device and method.
Background technology
Along with expanding economy and human living standard's raising, the also corresponding increase of water consumption sharp increase, quantity of wastewater effluent has aggravated the shortage and the body eutrophication problem of water resources.Eutrophication problem is one of topmost water pollution problems of facing of the world today.In recent years, though the wastewater treatment in China rate improves constantly, the water eutrophication problem that is caused by nitrogen and phosphorus pollution does not only solve, and serious day by day trend is arranged.As seen, the principal contradiction of sewage disposal is changed into the removal of nitrogen, phosphor contaminant gradually by the removal of organic pollutant.This just impels people that the conventional activated sludge method is transformed, to improve the clearance of nitrogen, phosphorus.Nitrogen compound is (as NH
4 +-N and NO
3 --N) molecular weight ratio is less, can't remove by adding medicament; In addition, if utilize membrane technique to remove nitrogen compound, it is the most effective that reverse osmosis membrane technology is only arranged.Therefore the removal of nitrogen is the difficult point and the emphasis of sewage disposal, and it is the most reasonable feasible to have only the bio-denitrification technology of utilization to be only.On the other hand, the phosphorus compound in the sewage utilizes bioremediation to be difficult for sometimes removing, but can realize satisfied phosphor-removing effect by the dispensing coagulation.Therefore, bio-denitrification technology is the key point of advanced treatment of wastewater.
The technology of current realization denitrogenation is a lot, the most representative technology mainly contains SBR method, A/O method, oxidation ditch process, hold shortcomings such as lay-up period is long, operation complexity yet the SBR method can only be applied in small sewage treatment plant, have the pond, seldom in the application of municipal sewage plant.And oxidation ditch process belongs to extended aeration technology, has the high shortcoming of capital cost and working cost.The A/O biological denitrification process is the abbreviation of anoxic/aerobic (Anoxic/Oxic) biological denitrification process, be that the present municipal sewage plant of China uses maximum a kind of denitrification process, denitrification moves under anoxia condition, the nitrated of the removal of carbonaceous organic material and ammonia nitrogen moves under aerobic condition, compares with traditional multi-stage biological denitrification process to have lot of advantages.But wastewater treatment in China factory biological denitrificaion ubiquity the energy consumption height at present, efficient is low and the shortcoming of fluctuation of service.Because the influence of the great variety of the city influent quality water yield and the fluctuation factors such as variation of seasonal temperature causes the fluctuation of A/O technology water outlet ammonia nitrogen concentration very big, the discharging phenomenon that exceeds standard often occurs.The severe overweight of water outlet ammonia nitrogen concentration will seriously increase the weight of the eutrophication of water body.Ammonia nitrogen can consume the dissolved oxygen of water body, makes algae excessive propagation, can increase water producing cost if this water is discharged in the source water.Sewage drainage standard is also more and more higher to the requirement of water outlet ammonia nitrogen concentration in addition, and it is poor that the sewage work of China more than 80% exists nitrification effect, the phenomenon that the water outlet ammonia nitrogen exceeds standard and discharges.To the control of aeration rate, major part is taked the control of constant aerating amount in the present municipal sewage plant, and small part adopts constant DO concentration control, does not consider the control of aeration rate from the system optimization aspect.Yet the municipal sewage plant's influent quality and the water yield alter a great deal in time, the external interference factor is many, if control in a manner described, effluent quality is defective when influent ammonium concentration is high; When influent concentration is low, cause aeration excessive, not only increase the systematic running cost while but also be easy to take place sludge bulking.Because China municipal sewage plant uses A/O art breading city domestic sewage or part trade effluent widely, in addition municipal sewage plant's aeration energy consumption account for the Sewage Plant working cost 50% or more, because the required working cost of sewage disposal is huge, secular, if by effectively control, the working cost of municipal sewage plant can be saved 1%, also be an astronomical figure.Therefore how to improve the technology nitrification efficiency, to solve the serious day by day water pollution problems of China, all there are important in theory meaning and realistic meaning present stage from aspects such as saving fund, raising wastewater treatment efficiency and optimization sewage water denitrifications in China.
Fuzzy control (Fuzzy Control) is the important component part and the pillar of intelligent control.Since zadeh proposes Fuzzy Set Theory, fuzzy control application in engineering increasingly extensive with deeply, particularly its research more is subjected to attracting attention of people with application achievements in recent years.Current, fuzzy control theory is applied in the online process control of various engineering systems.Yet the research of fuzzy control in water treatment and application are seldom, mainly concentrate on the SBR method, for example CN1387099A.For Continuous Flow biological denitrification process (being the A/O method), since the time variation of the dynamic of system complex, height and non-linear, the fuzzy control of being unrealized so far.Domestic control to A/O technology only is the continuous operation that has realized system, not the optimization of taking into account system operation and stability thereof.
Summary of the invention
The nitrifying method and On-line Fuzzy control device and the control method that the purpose of this invention is to provide a kind of A/O biological denitrification process solve the problem that A/O biological denitrification process operation condition is optimized intelligent control and improved stability; And solve that A/O biological denitrification process nitrification effect is poor, water outlet ammonia nitrogen concentration instability, problem that working cost is high.
Technical scheme of the present invention:
This A/O biological denitrification reactor, by anoxic pond, Aerobic Pond and second pond are formed, it is characterized in that: its anoxic pond has a lattice chamber at least, Aerobic Pond has two placed in-line lattice chambers at least, the oxygen-starved area is communicated with water inlet pipe, agitator is arranged in the anoxic pond, be provided with aerator in the Aerobic Pond, second pond is communicated with rising pipe, water-in is intake continuously, the water outlet continuous effluent, the second pond bottom connects excess sludge shore pipe and mud return line, and mud return line is communicated with water inlet pipe, connects sludge reflux pump therebetween, be connected inner circulating reflux pipe and inner circulating reflux pump between Aerobic Pond outlet and the anoxic pond inlet, outside in anoxic pond, also being communicated with carbon source add pipeline with outside carbon source add volume pump.
This A/O biological denitrification method according to claim 1 is characterized in that: carry out following adjusting in reaction tank:
(1), in the oxygen-starved area continuously stirring, carry out anti-nitration reaction, at the aerobic zone continuous aeration, carry out nitration reaction;
(2), when higher or water outlet ammonia nitrogen concentration is low when influent ammonia nitrogen load, increase the open degree of aerator air intake valve, improve aeration rate; Reduce the open degree of aerator air intake valve on the contrary;
(3), close or open the not air intake valve of the aerator of apposition chamber, thereby increase or reduce the volume ratio of Aerobic Pond and anoxic pond, and open or close the whipping appts in the corresponding reaction tank;
(4), increase or reduce the return sludge pump valve opening degree, thereby sludge concentration in the conditioned reaction device is nitrated required to satisfy;
(5), keep the opened condition of inner circulating reflux pump in the reaction tank operational process, keeping the nitrification liquid reflux ratio is 2;
(6), the spoil disposal of excess sludge shore pipe at interval, SRT maintains 12-15 days with the Controlling System sludge age.
The On-line Fuzzy control device of this A/O biological denitrificaion nitrifying process, it is characterized in that: in the A/O reactor, place three kinds of on-line sensors, gather the signal of dissolved oxygen (DO) concentration, influent ammonia nitrogen (SNHin), water outlet ammonia nitrogen concentration (SNHe) and sludge concentration (MLSS) concentration; Signal input analog digital conversion element A/D with gathering converts numerary signal to; Numerary signal is imported computer, uses fuzzy control rule, through obfuscation calculate adopt the Mamdani fuzzy algorithm carry out fuzzy reasoning, after non-Defuzzication calculates, obtain the fuzzy control variable; Convert the fuzzy control variable to control signal through digital-to-analogue conversion element D/A again; Control signal input topworks, sludge concentration in fuzzy control aerobic zone DO concentration, aerobic zone volume and the reactor in real time.
Above-mentioned fuzzy control rule such as following table:
Aerobic zone DO concentration fuzzy control rule table
Water outlet ammonia nitrogen (SNHe) influent ammonia nitrogen (SNHin) | XS | S | MS | M | ML | L | XL |
DO S M L | XS S MS | S MS M | MS M M | M ML L | M ML L | ML L XL | ML XL XL |
Above-mentioned fuzzy control rule such as following table
The MLSS fuzzy control rule table
Water outlet ammonia nitrogen (SNHe) MLSS | S | M Δr | L |
S M L | PS O NB | PB PS NS | PB PS O |
The On-line Fuzzy control method of this A/O biological denitrificaion nitrifying process, it is characterized in that: be built-in with dissolved oxygen (DO) concentration at reaction tank, influent ammonium concentration and water outlet ammonia nitrogen concentration and sludge concentration (MLSS) on-line sensor, the sensor is through lead and DO determinator, the ammonia nitrogen determination instrument is connected the back and is connected with the input interface of computer data signal with MLSS concentration determination instrument, the data signal output interface of computer, connect topworks, the aeration rly. of topworks through lead, the returned sluge rly., stir rly. through interface respectively with the gas blower valve, the return sludge pump valve is connected with the stirrer by-pass valve control;
The control of dissolved oxygen (DO) concentration: dynamically determine aerobic zone DO concentration set point according to influent ammonium concentration and water outlet ammonia nitrogen concentration application fuzzy control rule, and regulate the size of aeration rate, thereby keep the required DO concentration of aerobic zone; When higher or water outlet ammonia nitrogen concentration is higher when influent ammonia nitrogen load, increases the open degree of aerator air intake valve, thereby increase aeration rate; Reduce the open degree of aerator air intake valve on the contrary;
The control of aerobic zone volume: whether surpass the bound set(ting)value according to aerobic zone DO concentration and open or close the not air intake valve of apposition chamber aerator, thereby increase or reduce the volume ratio of aerobic zone and oxygen-starved area, and open or close the whipping appts in the corresponding reaction tank; DO concentration upper lower limit value is respectively 3.5mg/L and 0.5mg/L, when DO concentration surpasses 3.5mg/L, increases the aerobic zone volume, when aerobic zone DO concentration is reduced to 0.5mg/L, reduces the aerobic zone volume; But aerobic zone accounts for the reaction tank cumulative volume and only is no more than 85% than maximum, and minimum is not less than 35%;
The control of sludge concentration (MLSS):, use fuzzy control rule and dynamically control by water outlet ammonia nitrogen concentration and MLSS concentration; The sludge concentration maximum of reactor is no more than 5000mg/L, and minimum is not less than 1000mg/L;
The range of decrease degree that increases of each mud quantity of reflux is no more than 15%, and when not needing mud backflow fuzzy system and can satisfy nitrification effect, return sludge ratio gets 0.6.
Above-mentioned fuzzy control rule such as following table:
Aerobic zone DO concentration fuzzy control rule table
Water outlet ammonia nitrogen (SNHe) influent ammonia nitrogen (SNHin) | XS | S | MS | M | ML | L | XL |
DO S M L | XS S MS | S MS M | MS M M | M ML L | M ML L | ML L XL | ML XL XL |
Above-mentioned fuzzy control rule table reach for:
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " very little ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " little ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration is " little " and water outlet ammonia nitrogen concentration during for " intermediate value ", aerobic zone DO concentration is " intermediate value ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration was " neither big nor small ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " very little ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " intermediate value ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration be " in greatly ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " very big ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " intermediate value ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " very big ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " very big ".
Above-mentioned fuzzy control rule such as following table
The MLSS fuzzy control rule table
Water outlet ammonia nitrogen (SNHe) MLSS | S | M Δr | L |
S M L | PS O NB | PB PS NS | PB PS O |
Above-mentioned fuzzy control rule table reach for:
When sludge concentration in the reactor is " little " and water outlet ammonia nitrogen concentration during for " little ", returned sluge is than being " just little ";
When sludge concentration in the reactor be " little " and water outlet ammonia nitrogen concentration for " in " time, returned sluge is than being " honest ";
When sludge concentration in the reactor is " little " and water outlet ammonia nitrogen concentration during for " greatly ", returned sluge is than being " honest ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration when " little ", returned sluge is than " constant, as to keep original state ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration for " in " time, returned sluge is than for " just little ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration when " greatly ", returned sluge is than being " just little ";
When sludge concentration in the reactor is " greatly " and water outlet ammonia nitrogen concentration during for " little ", returned sluge is than being " negative big ";
When sludge concentration in the reactor be " greatly " and water outlet ammonia nitrogen concentration for " in " time, returned sluge is than being " negative little ";
When sludge concentration in the reactor is " greatly " and water outlet ammonia nitrogen concentration during for " greatly ", returned sluge is than being " constant, as to keep original state ".
Principle of work of the present invention: with the sanitary sewage is process object, by great deal of experimental, and under the different situation of influent quality, the internal relation between acquisition DO concentration, Aerobic Pond volume and MLSS concentration and the nitration reaction.Determine the optimized operation mode and the parameter of A/O technology removal organism and nitration reaction, improve the stability and the controllability of technology operation, provide fundamental basis for A/O technology nitration reaction realizes intelligent control.According to above-mentioned test-results and Intelligent Control Theory, set up A/O technology nitration reaction fuzzy control method.Wherein most important part is a The Design of Fuzzy Logic Controller, it comprise controlled variable Fuzzy processing, set up fuzzy control rule, make fuzzy decision, the non-Defuzzication of controlled variable is handled, and corresponding calculated machine algorithm, the fuzzy controller input variable comprises influent ammonium concentration, water outlet ammonia nitrogen concentration and MLSS concentration, and output variable comprises Aerobic Pond DO concentration, Aerobic Pond volume and sludge back flow quantity.The simulation test that the feasibility and the reliability of intelligence control system are carried out system is verified, and revised with perfect, until obtaining an On-line Fuzzy Controlling System accurately and reliably repeatedly.
Beneficial effect: the present invention can be according to sludge concentration in dynamic change control aeration rate, Aerobic Pond volume and the reaction tank of the influent quality and the water yield, hold the degree that nitration reaction is carried out exactly, avoid traditional control method Aerobic Pond DO excessive concentration or low excessively, aerobic zone volume deficiency (nitrated poor) or phenomenons such as excessive (nitrogen removal rate is low) and reaction tank sludge concentration deficiency.The DO excessive concentration can cause oxygen-transfer efficiency to reduce, and increases operation energy consumption, destroys the mud flco, and has a strong impact on the denitrification environment; DO concentration is low excessively, may cause the sludge settling degradation, causes sludge bulking and can cause N
2The generation of O.The present invention can not only improve A/O technology nitration reaction efficient, reduces the water outlet ammonia nitrogen concentration, reduce systematic running cost usefulness, and the nitrification efficiency of further other activated sludge process of raising also had important significance for theories and using value, the invention belongs to multi objective control.
The present invention compared with prior art has following advantage: flow process is simple, structures are few, and capital cost and working cost are lower, and floor space is little., can save outer carbon source and add expense, thereby reach sufficient denitrification as the denitrifying carbon source material with the carbonaceous material in the raw waste water and endogenous metabolism product.Aerobic Pond can further be removed the denitrification residual organic after anoxic pond, effluent quality is improved.Anoxic pond because denitrification has consumed most of organic carbon source, helped alleviating the organic loading of Aerobic Pond before Aerobic Pond, reduce the oxygen requirement of Aerobic Pond.The basicity that denitrification produces can be replenished in original water basicity deficiency and the nitrifying process consumption to basicity.The anoxic pond of A/O technology can play the effect of biological selector, helps controlling sludge bulking.Be easy in conventional activated sludge method system, reconstruct, realize satisfying higher water pollution control needs with the reconstruction investment of minimum.
The On-line Fuzzy control device is used for determining Aerobic Pond DO concentration, controls aeration rate and use traditional PI controller, keeps Aerobic Pond DO concentration.Can be under the situation that reduces the water outlet ammonia nitrogen concentration, reduce aeration rate as far as possible, simultaneously with influent ammonium concentration as feed-forward control signals, avoid merely with the water outlet ammonia nitrogen concentration as control signal, because the hysteresis quality of system causes water outlet ammonia nitrogen concentration fluctuation bigger.
The present invention is based on DO concentration and the Aerobic Pond volume jointly controls, can avoid Aerobic Pond DO excessive concentration, cross low and Aerobic Pond volume deficiency, can control Aerobic Pond DO concentration and Aerobic Pond volume in real time, save working cost as far as possible under the prerequisite of assurance water outlet ammonia nitrogen concentration qualified discharge.
The present invention has stipulated that DO concentration, Aerobic Pond volume account for minimum value and the maximum value of MLSS in reaction tank cumulative volume ratio and the reaction tank, it is excessive to avoid controlled variable to change, cause system's fluctuation of service, dangerous, increased security, stability and the reliability of system.
Dissolved oxygen (DO) concentration, ammonia nitrogen concentration and the MLSS concentration that the present invention's selection can onlinely detect, the time of response is short, tolerance range is higher is as the Be Controlled variable of A/O method nitration reaction process.These three controlled variable are topmost influence factors of nitration reaction, so native system has control accuracy height, characteristics that operational efficiency is high.
Management, easy to operate, expense is low.No matter how extraneous factor changes, all can realize nitrification effect preferably in addition, capacity of resisting impact load is strong, is difficult for taking place sludge bulking.
Regulate and control three parameters of sludge concentration in DO concentration, aerobic zone volume and the reactor according to the variation of the raw water quality water yield, guaranteeing to save energy consumption under the prerequisite of effluent quality, make that the A/O process reactor is able to efficiently, steady running.The present invention is directed to different influent qualities (different water inlet COD concentration, different influent ammonium concentrations, different flooding quantitys etc.), sludge concentration in DO concentration, aerobic zone volume and the reactor is made corresponding adjusting and control, solve the practical problems that the water outlet ammonia nitrogen concentration that occurs in the operational process is difficult to control and working cost is higher.Based on a large amount of experimental study data, a kind of apparatus and method of fuzzy control are provided for nitrifying process, for the application widely of A/O technology provides reliable operation, solved the existing problem of traditional constant aerating amount or constant DO concentration control A/O technology, solve A/O technology because the not enough caused nitration reaction of aeration rate, aerobic nitrification pond volume deficiency or MLSS is incomplete, caused the not up to standard or problem of higher of water outlet ammonia nitrogen concentration; Solve A/O technology simultaneously because aeration rate is too high or the problem of the excessive working cost raising that brings of Aerobic Pond volume, thereby reached high-level efficiency, low consumed processing horizontal, the optimization of enhanced process and control.
The A/O biological denitrification process is when handling sanitary sewage, by fuzzy control aerobic zone DO concentration, aerobic zone volume and sludge concentration, can realize COD and ammonia nitrogen removal frank more than 90% and 95%, the aeration energy consumption expense more than 15% be can save, thereby A/O technology nitrification effect instability, working cost problem of higher solved.
The present invention can be widely used in having adopted the sewage work of A/O technology or prepare to adopt the sewage work or the traditional activated sludge process transformation of A/O technology or extend is the sewage work with denitrification functions.
Description of drawings
Fig. 1 is the synoptic diagram of A/O biological denitrification reactor structure of the present invention;
Fig. 2 is the structural representation of A/O biological denitrification reactor On-line Fuzzy control device of the present invention;
Fig. 3 is the synoptic diagram of A/O biological denitrification reactor On-line Fuzzy control method step of the present invention;
Fig. 4 is the membership function figure of DO input variable-influent ammonia nitrogen (SNHin);
Fig. 5 is the membership function figure of DO input variable-water outlet ammonia nitrogen (SNHe);
Fig. 6 is the membership function figure of DO output variable-aerobic zone DO concentration (DO);
Fig. 7 is based on the response condition synoptic diagram of the Controlling System of DO fuzzy control rule;
Fig. 8 is the membership function figure of MLSS input variable-water outlet ammonia nitrogen (SNHe);
Fig. 9 is the membership function figure of MLSS output variable-mud Hui Liu Bi Lu.
Figure 10 is the membership function figure of MLSS input variable-sludge concentration;
Figure 11 is that permanent DO control and DO fuzzy control water outlet ammonia nitrogen concentration control result compare synoptic diagram.
The 1-water inlet pipe, the 2-intake pump, the 3-anoxic pond, the 4-agitator, the 5-aerator, the 6-Aerobic Pond, the 7-second pond, the 8-rising pipe, the 9-shore pipe, 10-inner circulating reflux pump, 11-inner circulating reflux pipe, the 12-ammonia nitrogen sensor, the 13-MLSS transmitter, the 14-DO transmitter, 15-ammonia nitrogen determination instrument, the 16-MLSS determinator, the 17-DO determinator, the 18-computer, the 19-signal input interface, the 20-signal output interface, 21-topworks, 22-aeration rly., 23-stirrer rly., 24-mud backflow rly., 25-aeration valve, the 26-return sludge pump, the 27-reflux sludge tube.
Embodiment
Referring to Fig. 1, the A/O biological denitrification reactor is by anoxic pond, Aerobic Pond and second pond are formed, it is characterized in that: its anoxic pond has a lattice chamber at least, Aerobic Pond has two placed in-line lattice chambers at least, the oxygen-starved area is communicated with water inlet pipe, agitator is arranged in the anoxic pond, be provided with aerator in the Aerobic Pond, second pond is communicated with rising pipe, water-in is intake continuously, the water outlet continuous effluent, the second pond bottom connects excess sludge shore pipe and mud return line, and mud return line is communicated with water inlet pipe, connects sludge reflux pump therebetween, be connected inner circulating reflux pipe and inner circulating reflux pump between Aerobic Pond outlet and the anoxic pond inlet, outside in anoxic pond, also being communicated with carbon source add pipeline with outside carbon source add volume pump.
Referring to Fig. 2, the working process of A/O biological denitrification reactor and the control method of nitrifying process: treatment sewage enters anoxic pond by intake pump, returned sluge also enters anoxic pond by second pond by reflux pump simultaneously, active sludge is stirred by whipping appts in anoxic pond, and the nitrification liquid that backflow comes with Aerobic Pond, with the nitrate nitrogen is that electron acceptor(EA), organic carbon source are electron donor, by the effect of denitrifying bacteria, carries out anti-nitration reaction.The anoxic pond water outlet enters Aerobic Pond then, carry out the nitration reaction of organic continuation degraded and ammonia nitrogen at this, utilize the online instrument of DO, ammonia nitrogen and MLSS to monitor sludge concentration in Aerobic Pond DO concentration, influent ammonia nitrogen (SNHin) and water outlet ammonia nitrogen concentration (SNHe) and the reactor in real time, by data-interface input fuzzy control device, fuzzy control device carries out fuzzy decision by fuzzy control rule to the data of being obtained, thereby output DO concentration, whether increases the aerobic zone volume or do not increase the indication of MLSS in the reactor.
Wherein DO concentration and MLSS concentration are realized by DO and MLSS fuzzy controller respectively, regulate DO concentration (the proportional gain Kp=500 of PID controller, integral parameter Ki=5 * 10 that aeration rate is controlled aerobic zone by the PID controller
6); And whether the Aerobic Pond volume reaches the highest and minimum concentration by Aerobic Pond DO concentration and determines, when the DO concentration of fuzzy controller output during greater than 3.5mg/L, then need increase the Aerobic Pond volume, then need reduce the Aerobic Pond volume on the contrary.Increase the Aerobic Pond volume as need, the whipping appts that then needs to cut out the last lattice of anoxic pond chamber opens the aerating apparatus valve; Increase MLSS concentration in the reactor if desired, then need to regulate the returned sluge revolution speed, thereby obtain required MLSS concentration according to fuzzy controller output result.Water outlet enters second pond at last, carries out mud-water separation at this, and supernatant is discharged by rising pipe, and mud concentrates in sludge bucket, and wherein a part is discharged with the form of excess sludge, and a part is back to anoxic pond by sludge reflux pump.
For fear of the frequent starting of operational outfit with close, the stability of raising system and reliability, control device is taked following measure when operation: real-time online is measured aerobic zone DO concentration, ammonia nitrogen concentration, the water inlet of on-line determination and water outlet ammonia nitrogen concentration data storing are in fuzzy controller, mean value with determination data in per 20 minutes, determine aerobic zone DO, avoid the error of ammonia nitrogen on-line determination instrument to cause the deviation of DO control, and frequent unlatching and the adjusting of gas blower, be a control cycle with per 20 minutes.In addition the control of aerobic zone volume neither DO concentration moment just increase the aerobic zone volume during greater than 3.5mg/L, equally with the DO concentration mean value in per 3 hours whether greater than 3.5mg/L or less than 0.5mg/L, increase the aerobic zone volume or reduce the aerobic zone volume.Avoid the alternately frequent of zone of transition running status, not only do not have effective function, frequent variations will cause the deterioration of mud performance, and operational outfit also can't bear.Sludge concentration control hierarchy is lower than control of DO concentration and the control of aerobic zone volume, after adopting the control of DO concentration and aerobic zone volume, still in the time of can't realizing the qualified discharge of water outlet ammonia nitrogen concentration, start mud backflow fuzzy control, more to avoid the huge fluctuation of sludge back flow quantity in the control process, with the water outlet ammonia nitrogen concentration of 3 hours mensuration and the mean value input fuzzy controller of sludge concentration, obtaining the mud quantity of reflux after the fuzzy controller fuzzy decision is the decision that increases or reduce, the range of decrease degree that increases of each mud quantity of reflux is no more than 15%, when not needing mud backflow fuzzy system and can satisfy nitrification effect, return sludge ratio gets 0.6.
Referring to Fig. 2, A/O technology fuzzy control device is intake by water inlet pipe 1 through intake pump 2, enter anoxic pond 3, and stir by stirrer 4 and to keep the muddy water mixed effect, the anoxic pond water outlet enters Aerobic Pond 6, keeps the aerobic condition of Aerobic Pond 6 by aerator 5, the Aerobic Pond water outlet enters second pond 7, water outlet is by rising pipe 8 dischargings, and excess sludge is through shore pipe 9 dischargings, and the nitrification liquid backflow is back to anoxic pond 3 by reflux pump 10 by return line 11.At the anoxic pond head end ammonia nitrogen on-line sensor 12 is set, be provided with DO transmitter 13 and sludge concentration meter 14 in each lattice chamber of Aerobic Pond, be built-in with ammonia nitrogen sensor 12 in Aerobic Pond water outlet (or the last lattice of Aerobic Pond chamber), the sensor is through lead and DO determinator 15, ammonia nitrogen determination instrument 16 is connected the back and is connected with the data signal input interface 19 of computer 18 with MLSS determinator 17, the data signal output interface 20 of computer, connect topworks 21, the aeration rly. 22 of topworks through lead, stirrer rly. 23 and return sludge pump rly. 24 through interface respectively with aerator air intake valve 25, stirrer 4 is connected with return sludge pump 26.
Referring to Fig. 3, A/O technology nitrifying process fuzzy control method is as follows:
(1) in Sewage treatment systems, places three kinds of transmitters, gather the signal of dissolved oxygen concentration (DO), sludge concentration (MLSS), influent ammonia nitrogen (SNHin) and water outlet ammonia nitrogen concentration (SNHe), as the Be Controlled variable of nitration reaction;
(2) DO, MLSS, SNHin and the SNHe value signal gathered are imported analog digital conversion element A/D through transmitter, convert numerary signal to;
(3) numerary signal is imported computer, through obfuscation calculate, with the fuzzy control rule comparison of input in advance, adopt the fuzzy predication method of Mamdani carry out the fuzzy control reasoning, after non-Defuzzication calculates, obtain the fuzzy control variable;
(4) convert the fuzzy control variable to control signal through digital-to-analogue conversion element D/A again;
(5) control signal is controlled topworks, directly controls controlled variable-aeration rate, aerobic zone volume and the sludge back flow quantity of nitration reaction.
With the fuzzy control parameter of DO concentration, determine DO concentration according to influent ammonium concentration and water outlet ammonia nitrogen concentration as aeration rate.Ammonia nitrogen concentration size and DO concentration can be described with the fuzzy language variable, so application influent ammonium concentration and water outlet ammonia nitrogen concentration, are used the output variable of DO concentration as fuzzy controller as two input variables of fuzzy controller.
Influent ammonia nitrogen (SNHin), water outlet ammonia nitrogen concentration (SNHe), DO concentration just are.Input variable SNHin and SNHe fuzzy set and domain are defined as respectively:
The fuzzy set of SNHin is: { S, M, L}
The fuzzy set of SNHe is: { XS, S, MS, M, ML, L, XL}
The domain of SNHin is: and 1,2,3,4,5,6}
The domain of SNHe is: and 1,2,3,4,5,6,7}
To manipulated variable U
ABe DO concentration, its fuzzy set and domain are defined as respectively:
The fuzzy set of DO is: { XS, S, MS, M, ML, L, XL}
The domain of DO is: and 1,2,3,4,5,6,7}
The implication of above-mentioned linguistic variable is respectively: XS (Very small): very little; S (Small): little; MS (Middlesmall): medium and small; M:(middle): the centre; ML (Middle large): in big; L (Large): big; XL (Verylarge): very big.
By the principle of fuzzy control as can be known, the input of fuzzy control device is to determine amount, and FUZZY ALGORITHMS FOR CONTROL itself requires fuzz variable.This just need become fuzz variable through Fuzzy processing with accurate input variable.Input variable, output variable are carried out Fuzzy processing, and fuzzy method sees Table 1-5.The membership function of each fuzzy set of input variable such as Fig. 4-10.Only the foundation of fuzzy rule is described at this, fuzzy control rule is as shown in table 6.When influent ammonia nitrogen SNHin concentration is big, and water outlet ammonia nitrogen SNHe hour is also kept lower aeration rate; When influent ammonia nitrogen SNHin concentration hour, and water outlet ammonia nitrogen SNHe also keeps higher aeration rate when big.This control law is at first to satisfy under the water outlet ammonia nitrogen prerequisite up to standard the expense that cuts down the consumption of energy as far as possible, the response condition synoptic diagram of Controlling System when Fig. 7 is based on the DO fuzzy control rule.
Table 1 turns to discrete integer variable X with SNHin
SNHin XSNHin | +1 | +2 | +3 | +4 | +5 | +6 |
SNHin(mg/L) | 0-15 | 15-30 | 30-40 | 40-50 | 50-60 | 60-+∞ |
Table 2 turns to discrete integer variable X with SNHe
SNHe XSNHe | +1 | +2 | +3 | +4 | +5 | +6 | +7 |
SNHe(mg/L) | 0-0.5 | 0.5-1 | 1-2 | 2-3 | 3-4 | 4-6 | 6-+∞ |
Table 3 turns to discrete integer variable X with DO
DO XDO | +1 | +2 | +3 | +4 | +5 | +6 | +7 |
DO(mg/L) | 0-0.3 | 0.3-0.8 | 0.8-1.5 | 1.5-2.5 | 2.5-3.5 | 3.5-5 | 5-+∞ |
The membership function assignment table of table 4 SNHin
Fuzzy set | XSNHin |
S is subordinate to M and belongs to the L degree | 1 | 2 | 3 | 4 | 5 | 6 |
0.8 0 0 | 0.4 0.4 0 | 0 0.8 0 | 0 0.6 0.2 | 0 0.2 0.6 | 0 0 0.8 |
The membership function assignment table of table 5 SNHe and DO
Fuzzy set | XSNHe and DO |
XS is subordinate to S MS and belongs to | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
1 0.8 0.3 | 0.6 1 0.6 | 0.2 0.3 1 | 0 0 0.4 | 0 0 0 | 0 0 0 | 0 0 0 |
M ML degree L XL | 0 0 0 0 | 0.3 0 0 0 | 0.6 0.3 0 0 | 1 0.8 0.2 0 | 0.2 1 0.6 0.2 | 0 0.4 1 0.6 | 0 0 0.4 1 |
Table 6 aerobic zone DO concentration fuzzy control rule table
Water outlet ammonia nitrogen (SNHe) influent ammonia nitrogen (SNHin) | XS | S | MS | M | ML | L | XL |
DO S M L | XS S MS | S MS M | MS M M | M ML L | M ML L | ML L XL | ML XL XL |
Above-mentioned fuzzy control rule table reach for:
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " very little ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " little ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration is " little " and water outlet ammonia nitrogen concentration during for " intermediate value ", aerobic zone DO concentration is " intermediate value ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration was " neither big nor small ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " little " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " very little ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " intermediate value ", aerobic zone DO concentration was " in big ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration be " in greatly ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " intermediate value " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " very big ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " very little ", aerobic zone DO concentration was " medium and small ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " little ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " medium and small ", aerobic zone DO concentration was " intermediate value ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " intermediate value ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " in big ", aerobic zone DO concentration was " greatly ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " greatly ", aerobic zone DO concentration was " very big ";
When influent ammonium concentration was " greatly " and water outlet ammonia nitrogen concentration " very big ", aerobic zone DO concentration was " very big ".
MLSS sludge concentration fuzzy controller:, determine the increment of sludge back flow quantity according to reactor MLSS concentration and water outlet ammonia nitrogen concentration with the fuzzy control parameter of MLSS concentration as sludge back flow quantity.As input variable of fuzzy controller, use the output variable of the Zeng Liang Lu of returned sluge ratio with reactor MLSS concentration and water outlet ammonia nitrogen concentration as fuzzy controller.The input and output variable can be described with the fuzzy language variable.
MLSS concentration, water outlet ammonia nitrogen concentration (SNHe) just are, and their fuzzy set and domain are defined as respectively:
The fuzzy set of MLSS is: { S, M, L}
The fuzzy set of SNHe is: { S, M, L}
The domain of MLSS and SNHe is: and 1,2,3,4,5,6}
For control Liang Lu, its fuzzy set and domain are defined as respectively:
The fuzzy set of Lu is: { NB, NS, O, PS, PB}
The domain of Lu is: and 3 ,-2 ,-1,0,1,2,3}
By the principle of fuzzy control as can be known, need accurate input variable is become fuzz variable through Fuzzy processing.Fuzzy method sees Table 7-9, and the actual domain in the table all is to determine by a large amount of tests.Fuzz variable must be represented with membership function.The specific form of membership function depends on the characteristic of Be Controlled system itself.The membership function of each fuzzy set of input variable, output variable such as Fig. 8,9,10.Can obtain their membership function table 10 and table 11 by the membership function of input/output variable.
The correlationship of detailed analysis between them sums up the control law near optimum control that does not rely on mathematical model, sets up the composition rule and the fuzzy control rule of the fuzzy control reasoning of representing with fuzzy language.According to the various situations that may run in the operating process and system's service data, control law is reduced table 12.
Table 7 turns to discrete integer variable X with SNHe
SNHe XSNHe | +1 | +2 | +3 | +4 | +5 | +6 |
SNHe(mg/L) | 0-1 | 1-3 | 3-5 | 5-7 | 7-9 | 9-+∞ |
Table 8 turns to discrete integer variable X with MLSS
MLSS X
MLSS | +1 | +2 | +3 | +4 | +5 | +6 |
MLSS(mg/L) | 0-500 | 500-1500 | 1500-2500 | 2500- 3500 | 3500- 4500 | 4500-+∞ |
Table 9 turns to discrete integer variable X Δ r with Δ r
XΔr | -3 | -2 | -1 | 0 | +1 | +2 | +3 |
Δr | -∞--0.2 | -0.2--0.1 | -0.1- -0.025 | -0.025- 0.025 | 0.025- 0.1 | 0.1-0.2 | 0.2- +∞ |
Table 10 MLSS and SNHe membership function assignment table
Fuzzy set | XSNHin |
S is subordinate to M and belongs to the L degree | 1 | 2 | 3 | 4 | 5 | 6 |
1 0 0 | 0.6 0.2 0 | 0.2 0.8 0 | 0 0.8 0.2 | 0 0.2 0.6 | 0 0 1 |
The membership function assignment table of table 11 Δ r
Fuzzy set | XSNHe and DO |
NB is subordinate to NS O and belongs to PS PB degree | -3 | -2 | -1 | 0 | 1 | 2 | 3 |
1 0 0 0 0 | 0.6 0.2 0 0 0 | 0 0.8 0.2 0 0 | 0 0.2 1 0 0 | 0 0 0.2 0.8 0 | 0 0 0 0.2 0.6 | 0 0 0 0 1 |
Table 12 MLSS fuzzy control rule table
MLSS | Water outlet ammonia nitrogen (SNHe) |
S | M | L |
S M L | PS |
0 NB | PB PS NS | PB PS | 0 |
Above-mentioned fuzzy control rule table reach for:
When sludge concentration in the reactor is " little " and water outlet ammonia nitrogen concentration during for " little ", returned sluge is than being " just little ";
When sludge concentration in the reactor be " little " and water outlet ammonia nitrogen concentration for " in " time, returned sluge is than being " honest ";
When sludge concentration in the reactor is " little " and water outlet ammonia nitrogen concentration during for " greatly ", returned sluge is than being " honest ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration when " little ", returned sluge is than " constant, as to keep original state ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration for " in " time, returned sluge is than for " just little ";
When sludge concentration in the reactor be " in " and the water outlet ammonia nitrogen concentration when " greatly ", returned sluge is than being " just little ";
When sludge concentration in the reactor is " greatly " and water outlet ammonia nitrogen concentration during for " little ", returned sluge is than being " negative big ";
When sludge concentration in the reactor be " greatly " and water outlet ammonia nitrogen concentration for " in " time, returned sluge is than being " negative little ";
When sludge concentration in the reactor is " greatly " and water outlet ammonia nitrogen concentration during for " greatly ", returned sluge is than being " constant, as to keep original state ".
Effect embodiment:
With the real life sewage of certain university dependents' district discharging be former water (pH=7-7.8, COD=180-450mg/L, TN=68-110mg/L).Selected A/O technological reaction pond useful volume is 300L, and MLSS is at 3000-4000mg/L in the reaction tank, and SRT maintains about 15d, temperature of reaction 20-23 ℃, the reactor inner circulating reflux than constant be 2.5, return sludge ratio is 0.5.With influent ammonia nitrogen and water outlet ammonia nitrogen concentration fuzzy control aerobic zone DO concentration, simultaneously the DO value of reactor aerobic zone is carried out online detection, organic matter degradation and nitrated situation in the real-time monitoring reaction device, this moment, system can maintain about 90%, 90% and 65% the average removal rate of COD, ammonia nitrogen and TN.And after adopting DO and aerobic zone volume comprehensively, ammonia nitrogen removal frank can be brought up to more than 95%, owing to improve aeration aerating efficient, systematic running cost reduces by 5% simultaneously.
Referring to Figure 11, permanent DO control and DO fuzzy control fruitage illustration, control with respect to permanent DO (2.5mg/L), Fuzzy control system can obtain effluent quality preferably, average water outlet ammonia nitrogen concentration has reduced by 18.1%, maximum water outlet ammonia nitrogen concentration has reduced by 11.9%, and the aeration operation energy consumption has reduced by 7%.Use fuzzy controller no matter influent ammonium concentration has much fluctuations, the water outlet ammonia nitrogen can satisfy emission standard 8mg/L.