The COST wastewater treatment plant simulation benchmark is a useful example for evaluation of control strategies aiming at improving biological nitrogen removal. In the SMAC project, the phosphorus removal process, based on the ASM2d model, was added as an extension to the existing benchmark wastewater treatment plant. This results in an example for evaluation of control strategies for combined nitrogen and phosphorus removal from wastewater, a necessity in the frame of the SMAC project. The phosphorus removal treatment plant is illustrated via a case study, where the addition of extra carbon source and metal salts for improving phosphorus removal are considered.