Instrumentation, control and automation (ICA) in wastewater treatment systems has come a long way and is now an established and recognised area of technology in wastewater systems. There are obvious incentives for ICA, not the least from an economic point of view. Wastewater treatment plants are also becoming increasingly complex which necessitates automation and control. This book is a follow-up of the 1st IWA Conference on Instrumentation, Control and Automation, held in 2001. It is not a conventional textbook or a manual of practice, but focuses on the leading edge technology where expect to get new understanding and development. The book is meant for: The practising process engineer and the operator, who wishes to get an updated picture of what is possible to implement in terms of ICA The process designer, who needs to consider the couplings between design and operation The researcher or the student, who wishes to get the latest technological overview of an increasingly complex field There is a clear aim to present a practical ICA approach, based on a technical and economic platform. The economic benefit of different control and operation possibilities is quantified. The more qualitative benefits, such as better process understanding and more challenging work for the operator are also described. The authors (Gustaf Olsson, Marinus Nielsen, Zhiguo Yuan and Anders Lynggaard-Jensen) are well respected experts in the international ICA community.