Aerobic granules for low‐strength wastewater treatment: formation, structure, and microbial community

Abstract

AbstractBACKGROUND: To validate the possibility of aerobic granulation at a lower organic loading rate (OLR) than 2 kg COD m−3 day−1 (GS 1) in a sequencing batch reactor (SBR), the formation, structure, and microbial community of granular sludge (GS) were investigated.RESULTS: The overall experimental process involved the following stages: acclimation, granulation, maturation, and stabilization. The optical microscopic showed the structural changes from fluffy activated sludge (AS) to GS and scanning electron microscope (SEM) examination revealed that GS 1 was irregular filamentous aggregates composed mainly of various filamentous species, while the aerobic granules cultivated at OLR 1.68–4.20 kg COD m−3 day−1 (GS 2) was mycelial pellets consisting of fungi and filamentous microorganisms. A Biolog Ecoplate analysis indicated that significant differences existed between the microbial community structure and the substrate's utilization of AS and different GS samples.CONCLUSION: GS 1 was achieved and different from GS 2 in the formation, structure, and microbial community. Aerobic granulation with low strength wastewater is of importance for the full‐scale application of this technology. Copyright © 2009 Society of Chemical Industry