Aerobic granular sludge with filamentous bacteria immobilized by string carriers to treat simulated municipal wastewater in a continuous flow reactor

Abstract

Aerobic granular sludge with filamentous bacteria (FAGS) has displayed many desirable properties. However, the selective pressure based on settling speed cannot effectively separate FAGS from water in sequencing batch reactor (SBR), which limits FAGS development. In this study, a new selection pressure was created by adding string carriers. Strings were used as crystal nuclei to form immobilized FAGS to achieve rapid separation from water. The immobilization of FAGS was achieved in both SBR and continuous flow reactor (CFR). The immobilization and long-term operation of FAGS in CFR were explored. NH4+ and COD removal efficiency remained above 90 % and 85 %, respectively. Sphaerotilus, denitrifying microorganisms and EPS-secreting microorganisms were the main microorganisms in the immobilized FAGS. The selection pressure provided by the strings, the operating characteristics of the CFR, and the properties of Sphaerotilus may play key role in the immobilization of FAGS.