Real Time Control (RTC) of wastewater treatment processes is an alternative to the present static, or time-invariant, mode of control during which wastewater in excess of a predetermined capacity is bypassed or diverted into an overflow. RTC control relies on modeling to predict the near future (i.e. next operation interval) influent loads, parameters and performance of the system and effluent water quality characteristics. Based on these predictions the RTC system and/or the operator can adjust and optimize the performance of the system using the control options built into the system itself. The paper describes the concepts of the RTC operational control of wastewater treatment facilities, modeling techology, strategy and applications.