Formation mechanisms and removal efficiency of aerobic granular sludge

Two types of mature aerobic granular sludge were respectively cultivated in the same two sequencing batch reactors(SBR) according to different formation mechanisms,using conventional flocculent activated sludge as seeding sludge.The mature aerobic granular sludge cultivated in R1 according to the hypothesis of filamentous bacteria,the SVI(sludge volume index) of the sludge was 35-45 mL/g,and the main diameter distribution ranged 2.0-4.0 mm.At the same time,another kind of the mature aerobic granular sludge was cultivated in R2 reactor according to the hypothesis of extracellular polymeric substance(EPS),the SVI of the sludge was about 30 mL/g,and the main diameter distribution ranged 1.0-1.6 mm.The results show that after cultivation finishing,the COD removal efficiency of both the reactors is similar(about 95%),but the removal efficiency of TN in R1 is higher than that in R2(the former is about 60% and the latter is about 50%).