Effect of superficial gas velocity on the granulation and metabolic characteristics of phosphorus removal sludge
In this study,the effect of superficial gas velocity on the granulation and metabolic characteristics of biological phosphorus removal sludge was investigated using a mixture of 60％sodium acetate and 40％soluble starch as the carbon source.The results showed that,unlike under the condition of small-molecule carbon source,the granulation of biological phosphorus removal sludge under complex carbon source condition was determined by both shear force and intracellular storage of carbon source,and the granulation process of the sludge was not completely consistent with the magnitude of the superficial gas velocity.R1 with the largest superficial gas velocity(0.45cm/s)achieved granulation on day 110,and R3 with the smallest superficial gas velocity(0.15cm/s)achieved granulation on day 190,which was slower than that in R1 but faster than that in R2(0.30cm/s).Decreasing the superficial gas velocity successively increased the content of filamentous bacteria and decreased the hydrophobicity of the tightly bound extracellular polymeric substance(TB-EPS);but the system was easier to meet the demand of anaerobic feast and aerobic famine,and the content of polyhydroxyalkanoates(PHAs)from anaerobic synthesis increased,and the corresponding content in R1,R2,R3 was 2.28,8.16 and 23.96mg/gVSS,respectively.High-throughput sequencing analysis of 16S rRNA genes showed that as the superficial gas velocity decreased,the abundances of Chloroflexi with hydrolysis and fermentation function successively increased,which were 7.86％,8.77％and 32.74％,respectively.At the genus level,Candidatus_Competibacter,a typical glycogen accumulating organism,was the key group for sludge granulation.The high superficial gas velocity in Rlwas beneficial to the maintenance and proliferation of this group,and the granulation process in Rl was the fastest.The superficial gas velocity in R3 was the lowest,and Kouleothrix(filamentous bacterium type 1851,belonging to the Chloroflexi)with the function of hydrolysis and fermentation thrived(10.44％in abundance),which promoted the proliferation of Candidatus_Competibacter(25.73％in abundance)by providing filamentous skeleton and small-molecule carbon source,thus accelerating the granulation of the sludge.
complex carbon sourcegranular sludgesuperficial gas velocityintracellular storagebacterial community structureeffect
万方数据
维普
