Real-time control of biological nitrogen removal is a major issue to advance the performances and the efficiencies of the wastewater treatment, especially when coupled to the processes via-nitrite pathway. Over the last three decades many researchers focused on indirect parameters (namely pH, DO, ORP, conductivity) to control the conventional nitrification and denitrification, up to several full scale applications. On the other hand, the real-time control to achieve and operate the processes via-nitrite is under investigation over the last years. This short review analyzes and discusses the main real-time control strategies and their most common and successful applications in sequencing batch reactors. In conclusion, the knowledge concerning the conventional processes will be outlined together with the next developments for short-cut nitrogen removal. (C) 2011 Elsevier B.V. All rights reserved.