MODELING, CONTROL AND ONLINE ESTIMATION OF ACTIVATED-SLUDGE BULKING

Sludge bulking is a problem widespread in the operation of activated s ludge processes. Over the past fifteen years much research has been ap plied to identifying the nature of the microbial species responsible f or bulking and to developing an understanding of their population dyna mics. While some isolated attempts have been made at developing a unit process model capable of simulating the behaviour of bulking, none ha ve been extensively evaluated against field data from full scale plant s, This paper describes the development of a multiple-species model of the activated sludge process (for both the reactor and settler), its application to the assessment of various operational strategies for th e control of bulking, and its simplification for incorporation into an on-line estimation scheme using a Kalman filter. Routine operating da ta from thee Davyhulme Wastewater Treatment Works in Manchester are us ed for identification (calibration) of the model. Simulation studies o f control strategies are based on the same Works. By using the Kalman filter to reconstruct real-time estimates of the ''unmeasurable'' stat es of the process model, the paper also explores the extent to which t his filter-based control can bring improvements over similar control b ased entirely upon conventionally measured operating variables.