Characteristics of aerobic granulation at different organic and ammonium compositions

Abstract

Aerobic granulation was characterized using three different wastewaters consisting of a sole organic substrate, a sole ammonium substrate, and combination of both organic and ammonium substrates. The formation of aerobic granules in each wastewater presented different physical, chemical, morphological, and microbial characteristics. The faster formation of larger and loose granules occurred at the high organic concentration of 1,000 mg COD/L; while the compact small size (0.6 mm) aerobic granules could be developed when nitrification was involved in aerobic granulation. The chemical changes and biomass growth were mainly dominated by heterotrophs and autotrophic nitrifiers. The simulation results of biofilm model demonstrated that the biofilm thickness depended on the substrate concentration at the outer surface and the attachment surface of granule's film. The formed granules can turn into media at a low substrate concentration for developing biofilms on the outer layer.