Karel Keesman received his Ph.D. for his work on set-membership identification and prediction of ill-defined systems, with application to a water quality system at the University of Twente in 1989. His main research interests focus on identification, modelling and control of uncertain dynamic systems with a biological component, as bioreactors, environmental and ecological systems, with more than 120 papers in international journals and refereed proceedings. For more than 25 years he is active in the field of system identification, in which he developed and applied identification methods to a wide range of problems.