A kind of method of utilizing intermittent aeration to realize sanitary sewage SBR nitrosification steady running
Technical field
The invention belongs to municipal sewage treatment and resource utilization field.Be specifically related to be exclusively used in the method for sanitary sewage SBR nitrosification steady running under normal temperature, different DO level.
Background technology
At present, biological denitrification phosphorous removal technique can be removed organism in sewage, nitrogen phosphorus and other pollutents and processing cost is low in sewage work, is used widely and develops because of it simultaneously.The ultimate principle of traditional biological denitrification process is that sewage is in biological denitrificaion treating processes, organic nitrogen is first changed into ammonia nitrogen by ammonifying bacteria, then ammonia nitrogen is converted into nitrite nitrogen and nitric nitrogen under the effect of ammonia oxidation bacteria (AOB) and NOB (NOB), nitric nitrogen is finally finally reduced to nitrogen under the denitrification of denitrifying bacteria, thereby completes the step of whole denitrogenation.Dissolved oxygen, inorganic carbon source (basicity), organic carbon source that whole process consumption is a large amount of, and the carbon source of sanitary sewage is not enough to meet the consumption of technique, needs additional guarantee treatment effect.Therefore traditional biological denitrification process has not only extended denitrification reaction course, and also causes the waste of the energy and additional carbon.
With short distance nitration (NH
4 +-NO
2 -) for the short-cut denitrification technology of core be the study hotspot of current nitrogenous effluent treatment.Realize short distance nitration, utilize the intrinsic difference of ammonia oxidation bacteria (AOB) and NOB (NOB) growth kinetics, nitrifying process can be controlled to NO by controlling the factors such as temperature, DO, pH, free ammonia (FA), SRT
2 -in the stage, stop it to be further oxidized, thereby form a large amount of NO
2 -accumulation.On this stage theory, comparable conventional art reduces 25% nitrated oxygen requirement, 40% carbon source and 50% sludge yield.But if will keep nitrosification operation steady in a long-term, operational conditions and influent quality are all extremely harsh, as low DO, high pH, high temperature, short SRT.And under low DO, ammonia oxidation speed is lower, sludge loading is lower, easily causes Filamentous Bulking; Under short SRT, mud easily runs off, and sludge discharge; NOB can progressively adapt to high FA and low DO environment.
DO concentration is the key factor that maintains nitrosification system stable operation.Be 0.2-0.4 mg/L because the avidity (DO semi-saturation number is 1.2-1.4 mg/L) of AOB to dissolved oxygen is greater than NOB(DO semi-saturation constant), therefore can under low DO, effectively realize the accumulation of nitrite.But the too low meeting of the mass concentration of DO causes aerobic nitrite bacteria to be subject to the inhibition of low-oxygen environment, and the mass concentration of DO is too high, can cause nitrite bacteria little to the competitive edge of nitrite-oxidizing bacteria, NO
2 --N cumulative percentage is low.In great majority research, while utilizing the aeration mode of continuous aeration to carry out normal temperature sanitary sewage SBR nitrosification, average DO concentration all below 3mg/L, its operation steady in a long-term of guarantee.If average DO is greater than 3mg/L, the activity of NOB can be recovered greatly, makes system be tending towards collapse.Therefore the long-term stability operation that how to ensure nitrosification system under high DO high oxidization rate requires study.
In sum, for the sanitary sewage under the low ammonia nitrogen condition of normal temperature, FA deficiency 1.00mg/L, FNA deficiency 0.01mg/L, based on temperature, FA, FNA, low DO suppression strategy, now can not effectively implement.Therefore how maintaining the nitrosifying long-term efficient and stable operation of sanitary sewage under the low ammonia nitrogen condition of normal temperature urgently studies.
Summary of the invention
The object of the present invention is to provide a kind of for city domestic sewage, be under normal temperature, low ammonia nitrogen condition, utilize intermittent aeration (it is 30-35min/10-15min that aeration stops the time of exposing to the sun) to realize sanitary sewage SBR nitrosification to maintain the method for steady running under basic, normal, high three kinds of initial DO levels.
The principle of intermittent aeration is, under anaerobic environment, the activity of AOB and NOB is suppressed, and ammonia oxidation process is obstructed, once and recover aeration, the AOB of experience long-term " hunger " can utilize ammonia production capacity to breed in a large number more, and NOB can not very fast activity recovery.In the time of intermittent aeration, stopping exposing to the sun also can make to occur that of short duration anaerobic environment, the condition of this low dissolved axygen are also conducive to the competition of AOB to matrix in system.As calculated, in Intermittent Aeration System, the Specific incremental rate of AOB is not subject to obvious impact, with the 0.60d of continuous aeration system
-1quite.In Intermittent Aeration System, the Specific incremental rate of NOB can decrease to some degree.Therefore Intermittent Aeration System can suppress the growth of NOB better, is more conducive to the steady running of sanitary sewage SBR nitrosification system under the high DO of normal temperature.
The invention provides a kind of method that maintains sanitary sewage nitrosification steady running under the low ammonia nitrogen condition of normal temperature, it is characterized in that:
In SBR nitrosation reactor, utilize the aeration mode of intermittent aeration, at three kinds of initial DO(0.5-1.0mg/L, 1.5-2.0mg/L, 2.5-3.0mg/L) under level, more than 20 days (40 cycles) of each DO level run, calculate COD concentration that COD clearance react removal and the ratio that reacts initial COD concentration, nitrous rate reacts the ratio of the nitrite of accumulation and the nitrite of accumulation and nitrate sum.If COD clearance all reaches more than 80%, nitrous rate all reaches more than 90%, illustrates under above three kinds of initial DO levels and all can ensure nitrosifying steady running.
The method that maintains nitrosification steady running provided by the present invention, it is the operation strategy by intermittent aeration, under normal temperature, low ammonia nitrogen condition, taking city domestic sewage as research object, inoculation nitrous rate reaches more than 95% nitrosification mud, at three kinds of initial DO(0.5-1.0mg/L, 1.5-2.0mg/L, 2.5-3.0mg/L) under level, realize the nitrosifying steady running of municipal effluent in sequence bioreactor (SBR) mode.Concrete steps are as follows:
Step 1: reactor is built
Reactor adopts sbr reactor device, and reactor is equipped with aerating apparatus, can be by regulating aeration rate to control the dissolved oxygen concentration in reactor waste water.Reactor arranges simple automatic control device, realizes automatic feeding water, reaction, precipitation, drainage flow path.
Step 2: seed sludge
The nitrous rate of inoculating high ammonia nitrogen water distribution startup reaches more than 95% nitrosification mud, is placed in sbr reactor device, passes into city domestic sewage, starts aeration.
Step 3: nitrosification mud laundering period
Controlling initial DO and be 0.5-1.0mg/L and aeration/stop the time of exposing to the sun is the intermittent aeration strategy of 30-35min/10-15min, ammonia nitrogen, sub-nitrogen, nitre nitrogen and the COD concentration of monitoring Inlet and outlet water every day, and calculate nitrous rate and COD clearance.Move 2 cycles every day, move 10 days more than (20 cycles).If COD clearance reaches more than 80%, nitrous rate reaches more than 90%, just illustrate that the nitrosification mud of high ammonia nitrogen water distribution startup has adapted to the environment of sanitary sewage, heterotrophic bacterium and autotrophic bacteria have reached certain running balance.
Step 4: nitrosifying steady running under three kinds of DO levels
Adopting aeration/stop the time of exposing to the sun is the intermittent aeration strategy of 30-35min/10-15min, and controlling respectively initial DO is 0.5-1.0mg/L, 1.5-2.0mg/L, 2.5-3.0mg/L, more than 20 days (40 cycles) of each DO level run.Ammonia nitrogen, sub-nitrogen, nitre nitrogen and the COD concentration of monitoring Inlet and outlet water every day, calculate COD clearance always all more than 80%, and nitrous rate is always more than 90%, and now the operation scheme of intermittent aeration can maintain the nitrosifying steady running of the low ammonia nitrogen sanitary sewage of normal temperature.
Compared with traditional continuous aeration method, advantage of the present invention is:
(1) compared with continuous aeration, in Intermittent Aeration System, the Specific incremental rate of AOB is not subject to obvious impact, and the Specific incremental rate of NOB can decrease to some degree.Therefore intermittent aeration is conducive to suppress the growth of NOB more, thereby is conducive to the long-term stability operation of nitrosification system.
(2) intermittent aeration, than the advantage of continuous aeration, is reflected more clearly while operation under high DO.And that high DO can solve under low DO sludge activity is low, a series of problem such as low and thread fungus expansion of ammonia oxidation speed.
(3) in addition, intermittent aeration is also expected to solve harshness requirement and the operation shortcoming of Short-Cut Nitrification Process to operational conditions and influent quality:
1) operational conditions harshness, high pH, high temperature, short SRT, low DO;
2), in long sludge age, NOB can progressively adapt to high FA and low DO environment;
3) under short SRT, mud easily runs off, and sludge discharge is large.
Below in conjunction with embodiment, the invention will be further described, but protection scope of the present invention is not limited to this.
Brief description of the drawings
Fig. 1 is reactor laundering period operating performance figure in the present invention, and wherein △ nitrite nitrogen is Inlet and outlet water nitrite nitrogen concentration difference; △ nitrate nitrogen is Inlet and outlet water nitrate nitrogen concentration difference.
Fig. 2 is (initial DO=0.5-1.0mg/L) the operating performance figure of reactor first stage in the present invention, and wherein △ nitrite nitrogen is Inlet and outlet water nitrite nitrogen concentration difference; △ nitrate nitrogen is Inlet and outlet water nitrate nitrogen concentration difference.
Fig. 3 is reactor subordinate phase in the present invention (initial DO=1.5-2.0mg/L) operating performance figure, and wherein △ nitrite nitrogen is Inlet and outlet water nitrite nitrogen concentration difference; △ nitrate nitrogen is Inlet and outlet water nitrate nitrogen concentration difference.
Fig. 4 is (initial DO=2.5-3.0mg/L) the operating performance figure of reactor reaction device phase III in the present invention, and wherein △ nitrite nitrogen is Inlet and outlet water nitrite nitrogen concentration difference; △ nitrate nitrogen is Inlet and outlet water nitrate nitrogen concentration difference.
Embodiment
Test is taking certain community life sewage as basic water, and concrete water quality is as follows: COD=300-400mg/L, BOD
5=120-150mg/L, SS=76-114 mg/L, TP=5.75-6.30mg/L, NH
4 +-N=75-90mg/L, NO
2 --N≤0.25mg/L, NO
3 --N≤1.5mg/L, TP≤1mg/L, pH=7.0-7.8, basicity is that 550.59-610.78mg/L(is with CaCO
3meter).
Concrete processing is as follows:
(1) stage adaptive phase
Reactor inoculation be that the nitrous rate being started by high ammonia nitrogen water distribution reaches more than 95% nitrosification mud, process at normal temperatures sanitary sewage, adopt the aeration control strategy of intermittent aeration, aeration/stop the time of exposing to the sun is 30min/10min.Be the high ammonia nitrogen water distribution without COD due to what start the employing of nitrosification mud, cause the number of heterotrophic bacteria in seed sludge extremely low, show that in front several cycle, COD clearance is very low.Therefore plant mud and need make heterotrophic bacterium propagation through one period of adaptive phase, the initial DO of adaptive phase adopts 0.5-1.0mg/L.When after 10 days (20 cycles) of operation, the heterotrophic bacterium in mud is increased in a large number, and COD clearance raises gradually, and the COD clearance in the 19th cycle reaches more than 80%, and water outlet COD is below 50mg/L, and this also indicates that the adaptive phase finishes.The ammonia oxidation rate in stage adaptive phase maintains more than 80% always, and nitrosification maintains more than 98%.Because DO is extremely low, sludge activity is very low, causes ammonia nitrogen volumetric loading and sludge loading very low, respectively at 0.15-0.2kgN/m
3/ d and 0.05kgN/kgMLSS/d left and right.As shown in Figure 1.
(2) first stage
After adaptive phase finishes, continue to keep 40 cycles of level run that initial DO is 0.5-1.0mg/L, ammonia oxidation rate maintains more than 80% always, and nitrous rate maintains more than 95%, and COD clearance remains on more than 80%.Illustrate that initial DO level is the steady running that 0.5-1.0mg/L can keep SBR nitrosification system.Ammonia nitrogen volumetric loading and sludge loading remain on the level of adaptive phase substantially, respectively at 0.2-0.25kgN/m
3/ d and 0.05kgN/kgMLSS/d left and right.As shown in Figure 2.
(3) subordinate phase
Continue to improve initial DO to 1.0-1.5mg/L, the running condition of observing nitrosation reactor.(40 cycles) rear ammonia oxidation rate maintains more than 80% always to move 20 days, and COD clearance is more than 80%, and nitrosification maintains more than 95%, still can ensure the steady running of nitrosification system.Due to the raising of DO, the activity of AOB increases, and ammonia oxidation speed improves, and has had raising to a certain degree when therefore ammonia nitrogen volumetric loading and sludge loading are than DO=0.5-1.0mg/L level, is respectively 0.3-0.4kgN/m
3/ d and 0.08kgN/kgMLSS/d left and right.As shown in Figure 3.
(4) phase III
Continue to improve initial DO to 2.5-3.0mg/L, can observe nitrosation reactor steady running.(40 cycles) rear ammonia oxidation rate maintains more than 80% always to move 20 days, and COD clearance is more than 80%, and nitrous rate maintains more than 90%, has realized the nitrosifying steady running of sanitary sewage SBR under high DO.Improve DO and make ammonia nitrogen volumetric loading and sludge loading have further raising, be respectively 0.5-0.65kgN/m
3/ d and 0.15kgN/kgMLSS/d left and right.
Afterwards again continue keep 2.5-3.0mg/L DO level run 15 days, COD clearance is always more than 80%, nitrous rate also maintains more than 90% always, illustrates that nitrosification system has reached the state of steady running really.As shown in Figure 4.
This test utilizes the normal temperature sanitary sewage SBR nitrosification system of intermittent aeration mode (aeration/stop the time of exposing to the sun be 30min/10min) operation at low DO(0.5-1.0mg/L), middle DO(1.5-2.0mg/L) and high DO(2.5-3.0mg/L) condition under efficiently remove in all can realizing steady running and COD and ammonia nitrogen.