The application of a single sludge activated sludge system to the treatment of combined municipal and industrial wastewaters from the Kohtla-Jarve region of Estonia is evaluated as an option to meet the carbon, nitrogen, and phosphorus effluent requirements for discharge to the Baltic Sea as stipulated by the "Helcom Recommendations." Literature are reviewed and current facility operations data are developed to assess the potential of achieving nitrification, denitrification, and biological excess phosphorus removal with a wastewater treatment plant that processes industrial wastewaters that contain phenolics and other inhibitory organic compounds which can suppress ammonia-nitrogen oxidation by activated sludge. The evaluation concludes that single sludge activated sludge systems for biological nutrient removal may not be appropriate for the treatment of complex industrial wastewaters, and selection of this biological treatment process without first conducting pilot-scale rests to verify, the performance of the technology in this application is not recommended.