Aerobic granular sludge microbial communities in reactors fed with synthetic and real wastewater

Basic understanding of aerobic granular sludge (AGS) processes has mainly been obtained in laboratory-scale studies with simple synthetic wastewaters. The microbial communities, settling properties and nutrient-removal performances were monitored during the strat up of four AGS sequencing batch reactors fed with four different wastewater (2 synthetic and 2 municipal). The microbial communities diverged from their activated sludge performing enhanced phospshorus removal inoculum for several months and stabilized into tree distinct stable states, the microbial communities of the AGS treating municipal wastewater being very similar. Good nutrient removal were kept in the four reactors. However, total nitrogen removal and settling velocities of the sludge were lower in the reactor treating complex wastewater compared to the one in the reactor treating synthetic wastewater with acetate and propionate as only carbon source.