Nitrogen (N)- and phosphorus (P)-containing inorganic ions are the key nutrients present in wastewater that need to be transformed and removed before treated water is discharged into receiving waters or reclaimed for beneficial uses. In Singapore, N removal is part of the planned design of water reclamation plants. Our research aims to improve the efficiency of N removal by understanding and implementing the forces that select for specific biochemical pathways in treatment plant. Until recently, there was no planned biological P removal at any of the full-scale treatment plants. SCELSE’s research has led to the discovery of unplanned enhanced biological P removal (EBPR) at one full-scale plant in Singapore and unravelled the mechanism behind it. We are now monitoring the performance of other full-scale plants and try to understand the relationship between communal carbon utilization patterns and specific microbial communities that are involved in EBPR.