This investigation includes three years of full‐scale experiences at the first EBPR plant in Norway, Groos WWTP in Grimstad. The main focus was on low temperature performance (below 7 °C) and the effect of wastewater characteristics (COD). The treatment efficiency was not affected by low temperature; 0.35 mg/1 phosphorus in the effluent during 1998 (94 % removal). COD‐levels, however, did affect the process. The results from the study are used as a basis for retrofitting plants that removes phosphorus by chemical precipitation. Results from experiments at a partly retrofitted plant are also presented.