Random signal analysis in an environmental sciences problem

Abstract Two major difficulties are encountered in the identification of wastewater treatment plant and river water quality dynamics: process behaviour can neither be easily observed, nor easily experimented upon, and the underlying biological nature of the processes involved is only partially understood. This paper describes the derivation of a model for the interaction between dissolved oxygen (DO), biochemical oxygen demand (BOD), and algae in a freshwater river. Noisy measurements from a stretch of the River Cam downstream of Cambridge are analysed using various techniques of identification, parameter estimation and filtering. An important feature of the paper is the interpretation of system identification as a hypothesis testing/decision making procedure.