Impact of the substrate composition on enhanced biological phosphorus removal during formation of aerobic granular sludge

Performance of enhanced biological phosphorus removal (EBPR) is often investigated with simple synthetic wastewater containing volatile fatty acids (VFAs). In this study, various (fermentable) substrates, individually and in mixtures, were examined during the application of a granulation strategy. In addition, the microbial community and N2O formation were monitored. Sludge densification was observed in all systems. Stable EBPR, associated with the presence of Accumulibacter and an anaerobic P-release up to 21.9 mgPO(4)(3-)-P.gVSS(-1), was only obtained when VFAs were present as sole substrate or in mixture. Systems fed with VFAs were strongly related to the formation of N2O (maximum of 6.25% relative to the total available nitrogen). A moderate anaerobic dissolved organic carbon (DOC) uptake was observed when amino acids (64.27 +/- 3.08%) and glucose (75.39 +/- 5.79%) as sole carbon source were applied. The substrate/species-specific enrichment of Burkholderiaceae and Saccharimonadaceae respectively, resulted in unstable EBPR in those systems.