Research on the effect of hydraulic shear stress on the formation of aerobic granular sludge

The experimental study of aerobic granular sludge in sequencing batch reactor (SBR) was performed using a synthetic domestic wastewater and ordinary flocculent activated sludge from the third Sewage Treatment Plant in Xi´an as seeding sludge. The aerobic granular sludge was cultivated successfully when the superficial upflow air velocity was 1.06~1.77 cm/s. The study suggests that the formation of granular sludge is a process of the formation of micro-ecological system. Hydraulic shear stress is a significant impact factor of its formation, which affects the composition of microbial population structure and distribution in aerobic granular sludge. From the analysis of the relationship between filamentous microorganisms and microbial community, zoogloea and filamentous bacteria depend on each other. The filamentous microorganisms formed floc skeleton, which provide the necessary condition for floc to form larger floc particles.