The respiration rate of activated sludge has generated much interest, because it is an essential variable in the activated sludge process and provides information on biomass activity and concentration of waste components. Recognising the need for an extensive evaluation of respirometry in control of the activated sludge process, IWA published Scientific and Technical Report (STR7): Respirometry in Control of the Activated Sludge Process: Principles, which included the biological background, measuring principles, measured and deduced variables, an introduction to control system principles and...