Rapid Cultivation Of Aerobic Granular Slude And Its Reactivation After Storage

Aerobic granular sludge(AGS)has many advantages,which make it one of the most promising microbiological wastewater treatment technologies.However,defects such as long startup time,poor stability and high aeration energy consumption of AGS technology have been the limiting factors of the application and spread of the technology.Therefore,two ways were employed in this study to promote the rapid formation of AGS.One was utilizing elastic filler which is quickly attached to biofilm and the other was inoculation of part of the anaerobic granule during the culture process.And this study also used different methods to store the AGS which was rapidly formed in those two ways mentioned above,and explored the application of shallow aeration to reduce energy consumption of reactor aeration and its effect on AGS stability.The main contents of the study and the results are as follows:(1)This study combined the method of attaching elastic filler to biofilm and another method of selective pressure in order to explore the effect of artificial stripping of biofilm and the inoculation of biofilm into mixed liquor on the culture process during the process of AGS.The experimental results show that the free biofilm is similar to the nucleation in the reactor.The free biofilm promoted flocculation of floc sludge under the larger selection pressure,and gradually converted into dense particle state.Finally,the granulation is completed within 30 days in the winter condition.(2)After the start-up of SBR,where activated sludge was inoculated,the study investigated the effect of partial anaerobic granular sludge inoculated on granulation process during the culture of AGS under selective pressure on.On the 11 th day,20%(w/w)anaerobic granular sludge was inoculated into the reactor,and the granulation rate of AGS was over 90% on the 26 th day,which means the aerobic granulation was successfully realized,and the self-agglomeration time of microorganisms was effectively shortened.(3)In order to explore the stability and recovery effect of AGS at room temperature,the experiment set two different conditions of wet storage of AGS: One is open storage and the other is sealed storage.The recovery process needed only 12 days to complete,and after the AGS entered aeration,the content of EPS,the rate of aerobic,dehydrogenase and so on rapidly increased to respectively between 175.24 and 190.23 mg/g MLSS,and 33.33 mg/g MLSS h.100 to 120 mgTF/(g SS·h).After the recovery of stability,the reactor showed good pollutant removal efficiency,and its physicochemical properties were significantly better than before storage.(4)The storage effect and subsequent reactivation of AGS embedded by agar under room temperature and refrigeration conditions(4 ?)were investigated.After 30 days' storage,AGS in the two conditions were both characterized by a sharp decline of MLVSS,SOUR and other properties.Under aerobic conditions,the activity recovery process was completed on the 22 nd day.During the period,the removal rate of COD,TIN and TP remained over 90% after recovery.After the agar storage,SOUR remained above 10 mg O2·g-1 MLSS-1 h-1,and the EPS was not obviously reduced after storage.Besides,no significant decrease in EPS was observed after storage,indicating that agar storage can not only maintain the morphology of AGS,but also maintain the effect of microbial activity.(5)In order to explore the feasibility of the combination of shallow aeration,SBAR and AGS,the experiment gradually raised the position of the aerator under the water surface(130~30cm),to find how stability of the AGS changes.It was found that the aeration amount increased from 400 L/h to 500 L/h,DO decreased from 8 mg/L to 5.88 mg/L,and the cycle speed was reduced from 27.25 cm/s to 11.39 cm/s in the process of raising the position of the aerator.When the aeration depth was more than 70 cm,the stability was maintained well,and the physical and chemical properties were maintained at the normal level.When the aeration depth was or less than50 cm,the hydraulic shear force was greatly reduced and the mass transfer resistance to oxygen was increased,resulting in the rapid reduction of the granulation rate and the EPS,and the degradation of the pollutants removal.At this time,the AGS was obviously disintegrated.The system was out of order.It is unusual.