@TechReport{	  it:2003-030,
  author	= {M. Ekman and P. Samuelsson and B. Carlsson},
  title		= {Adaptive Control of the Nitrate Level in an Activated
		  Sludge Process Using an External Carbon Source - Extended
		  Version},
  institution	= {Department of Information Technology, Uppsala University},
  department	= {Division of Systems and Control},
  year		= {2003},
  number	= {2003-030},
  month		= may,
  note		= {A shorter version is also available in: Preprints of
		  Reglerm{\"o}te 2002, Link{\"o}ping, Sweden, May 29--30
		  2002, pp 308--313, and another version in: Proc. of the 1st
		  World Water Congress of the IWA. Melbourne, 2002 (poster
		  presentation). Updated July 2003},
  abstract	= {In an activated sludge process for nitrogen removal,
		  nitrate may be reduced to nitrogen gas by facultative
		  heterotrophic bacteria in an anoxic environment. In order
		  to guarantee sufficient supplies of readily biodegradable
		  carbon compounds, an external carbon source often needs to
		  be added. In this report, we present an automatic control
		  strategy for controlling the nitrate level using an
		  external carbon source. The external carbon source is added
		  in the first anoxic compartment and the nitrate
		  concentration in the last anoxic compartment is controlled.
		  Key process parameters of a simplified Activated Sludge
		  Model No. 1 are estimated on-line. The estimated parameters
		  are used for updating the parameters of a linear quadratic
		  controller. The strategy is illustrated in a simulation
		  study using realistic influent data and is shown to perform
		  well.}
}