Research On Contolling The Formation Of Granular Sludge With OUR And The Recovery Process After Storage

At present,biological treatment technology was more used by domestic sewage treatment,and aeration tank is an important part of biological treatment.If the aeration is too small,it will cause dissolved oxygen deficiency,resulting in filamentous bacteria swelling;and the large aeration will form a strong air stirring,resulting in floc fragmentation,affecting the water quality.Aerobic granular sludge has gained more and more attention and research in recent years because of its good sedimentation,impact loading capacity and diverse microbial populations.But if we cannot control the the key conditions such as aeration properly,the stability of granular sludge will be difficult to control,which is the reasons why it cannot large-scale used in the actual water plants.The existing water plants only depend on water quality or experience to adjust the aeration,which is clearly not conducive to the stable operation of activated sludge system.In addition,most of the studies on the stability of granular sludge are related to the basic form of the sludge,the structure of the reactor,the control of the influent load and so on,but the respiration rate is rarely studied.Therefore,the experiment used two identical SBR reactors,using a new aeration control method,that is,adjusting the aeration rate according to the microbial respiration rate,and comparing with the conventional aeration control method that is adjusted according to the water quality.On the one hand,exploring the new aeration control method to maintain the stability of actived sludge system;On the other hand,studying the changes of physicochemical and respiration rate of activated sludge under different aeration modes,which provides the basis for the stable operation of sewage and laboratory activated sludge system.In addition,the actived sludge in the practical application sometimes need to be stored for a long time,this experiment studied and analized after a month storage of different traits of granular sludge recovery process of physical and chemical characteristics and respiratory characteristics.The main results of this study are:1:The sludge form had many differences under different aeration control mode.For the granular sludge system,controlling the aeration according to the effluent quality is the conventional control method,it can not track the actual oxygen demand,prematurely cause the expansion of granular sludge,resulting in system instability.Respiration rate increased after the formation of granular sludge,adjust according to microbial respiration rate to of real-time monitoring of microbial oxygen demand is more conducive to stable operation of granular sludge system.2:Acridine orange staining can significantly reflect the change of microbial RNA and DNA in the working process of granular sludge system.With the form of granular sludge,the number of RNA increased,and the number of RNA increased sharply when filamentous bacteria swell.3:There were no significant differences in the effluent quality of granular sludge from different traits,but the difference of respirogram was significant,which indicated that the respiration rate had higher sensitivity relative to water quality and it can respond changes and status of microbial population in time.4:The total respiration rate and endogenous respiration rate in process of granular sludge formation are rapidly increasing,and the endogenous respiration rate is stable after granular sludge stabilization,and the respiration rate of autotrophic bacteria has a strong regularity and can indicate the changes of microbial;the variety of respiration rate of endogenous and autotrophic bacteria accompanied by filamentous bacteria is large.5:The total respiration rate of granular sludge is much larger than that of ordinary floc sludge,and the proportion of endogenous respiration is also lower than that of floc sludge,indicating that the granular sludge can remove more pollutants and have the potential of energy saving.6:Place the traits of different traits for a month,It can be seen from the respirogram that the granular sludge is almost lost.But after the reactor is restarted,the granular sludge and filamentous granular sludge both recovered the activity.R1 respiration rate increased,but R2 decreased.The autotrophic respiration rate,heterotrophic respiration rate and total respiration rate were significantly increased in the two reactors.After the recovery of the activity,the stable granular sludge reactor operating cycle decreased from 6 cycles to 3 cycles a day,increasing the aeration time,the sludge concentration decreased,but the change of the respirogram was smaller.R2 increased the settling stability in the short term after a certain improvement,but still can not eliminate the filamentous bacteria,resulting in the reactor deterioration and caused by sludge loss.