[Biodegradability of extracellular polymeric substances (EPS) produced by aerobic granules]

Aerobic granules were cultivated with synthetic wastewater and were added in the course of aerobic starvation. Results showed that EPS produced by aerobic granules was composed of 40% biodegradable and 60% nonbiodegradable EPS. Among these, only biodegradable EPS could be utilized by their producers, while nonbiodegradable EPS contributed to maintain the spatial structures of aerobic granules. EPS extracted from fresh aerobic granules was fed as the sole carbon source to their own producers and activated sludge and was utilized by them. The average biodegradation rate of activated sludge in terms of EPS was 1.5 times faster than that of aerobic granules. When EPS extracted from starved aerobic granules was fed as the sole carbon source to their own producers and activated sludge, it could not be utilized and could not be energy source.