Microbial Community And Diversity Of Microfauna During The Cultivation Of Aerobic Granular Sludge

Aerobic granular sludge(AGS)is a kind of new wastewater treatment technology,which has a higher activity and tolerance than suspended biological filler.AGS has great sedimentation and treatment effect of organic matter per unit volume compares to the conventional activated sludge,which can withstand high impact load,reduce the requirements of the secondary clarifier volume and could removal nitrogen and phosphorus at the same time.Due to the different methods and experimental conditions,it is difficult to reach a consensus on the formation mechanism and culture methods of AGS.With the granular sludge for culture,the system will start-up very fast.which could clearly shorten the culture period.The down side is that the granular sludge is expensive,AGS is more scarce.Therefore it is not suitable for large-scale practical engineering application.Many studies have shown that the microfauna in the process of granulation played an important role.The diagnosis of biological phase in the traditional activated sludge has been relatively mature,with AGS has richer and more complex ecosystem to be studied.On this perspective of view,this paper illustrates the exploration of the species diversity and stability of the microfauna in the formation of the granular sludge based on the culture of AGS.SBAR(Sequencing Batch Airlift Reactor)was used in the experiment,and the AGS was cultured by using sucrose,beef peptone and potato starch as the nutrient.Research shows that the inoculation of activated sludge(R1)and the other on the basis of adding anaerobic granular sludge(R2)and iron hydroxide floc(R3)as crystal nucleus under the condition of domestication of mature,AGS successful time are about 45 d,the 3 groups in the reactor eventually mature AGS diameter respectively COD removal rate: 93%;NH+4-N removal rate reached 97.5% in the 50d;0.5mm particle sedimentation rate were 5.647 cm/s,5.756 cm/s,5.682 cm/s;the moisture content was 96%,95%,95%;the specific oxygen uptake rate(SOUR)were: 2.19 mg O2/(MLVSSg·min),2.36 mg O2/(MLVSSg·min)and 2.63 mg O2/(MLVSSg·min);dehydrogenase activity was 3.517 g TF/(mg MLSS·h),5.889 g TF/(mg MLSS·h),6.485 g TF/(mg MLSS·h);.Sludge settling performance SVI between 20~30ml/g.R2 and R3 can be seen in the daily microscopic examination,the roundness and integrity of the particles are higher than R1,and the microbial activity R2,R3 is significantly greater than R1.In the comparative study of organic nucleus,R1 is still in control group,adding anaerobic granular sludge in the experimental group(R2)and crushed anaerobic granular sludge particle(R3),in the case of low organic loading in the 50 d developed a stable AGS.The removal rates of COD,TN and were 95%,70% and NH4+-N,respectively,MLSS,5.5,6.0g/L,SVI,and finally stabilized to: 35 m L/g;sedimentation rate were: 4.886 cm/s /4.986 cm/s /4.935 cm/s.R1,R2 and R3 were formed in 55 d,50d and 40 d,we can see that the fragmentation of anaerobic granular sludge dosing is better than conventional activated sludge is more conducive to promoting the granulation of flocculent sludge,but the particle shape R3 is not uniform,and the stability and anti impact capability is poor.After the temperature is reduced,R3 is first broken.Taking ordinary activated sludge and bio ferric sludge granulation process in micro animal community as the research object,changes of population domestication process were investigated in the AGS microfauna community structure and advantages,and compared two sets of AGS system with the community species diversity,stability and microbial index(SBI)in the granulation.The results show that the AGS culture in microfauna community early than activated sludge acclimation period of the evolution of similar population after the increase in the first stable process: the structure of micro animal diversity and community stability after particle formation and lag behind the stable treatment effect(COD,TN,TP etc.).By observing the control group R1 and iron R2,the stability of the species and the stability of the diversity of the micro animals,compared with the R1.In the early stage of domestication,the stability of R2 is worse than R1.After the particle maturation,the stability of R2 is better than R1.Through the research on the formation of different methods of AGS,domesticating stable AGS of different performance with a faster time,and analyzing the micro animal community formed in the process.The results show that the difference in population succession community structure in the process of microfauna in AGS and activated sludge.In the process of AGS formation,the interaction between the microfauna,hydraulic pressure(settling time)and hydraulic shear force(aeration intensity,reactor configuration,etc.)plays an important role in granulation.The utilization of crystal nucleus can promote the formation of particles,and the effect of some of the properties of mature AGS.In addition,the utilization of iron flocs had a great influence on the structure of the micro organism community.In different stages,the stability of the microfauna and diversity of the system were different from those of the control group.