The paper presents studies regarding the efficiencies of the removal process for ammonia, nitrites, phosphorus and detergents, in the Constanþa city municipal wastewater treatment plant, during 2007. The pollutants mean concentrations in the effluent, in the studied period, have been according to the imposed limits, but some slightly higher values have been noticed for ammonia during July – October and for total phosphorus during January - March, September and December. The obtained results show that during 2007 high removal efficiencies for ammonium nitrogen (84.79%) and detergents (95.96%) have been obtained but low percentages for phosphorus (47.01%), showing that some operational measures should be taken, in order to improve the removal performances.