Book excerpt: Ebook only (available soon) The report describes the principles of measurement of respiration rate, the transformation of measurement data into other types of information, and the application of the obtained information in process control strategies. Some fundamental concepts on biological respiration and process control are provided to assist the reader with understanding the principles. A structured overview comprises some eighty control strategies in which respirometry plays a role. To enable the reader to consult the information sources, an extensive literature list of over 500 references in included and classified into six themes. Contents Fundamentals of Respiration Measuring Principles Measured and Deduced Variables Elementary Control Concepts Respirometry in Control of the Activated Sludge Process Summary and Perspectives. Scientific and Technical Report No.7 Also Available Respirometry in Control of the Activated Sludge Process: Benchmarking Control Strategies