Abstract
In paper processes, the variability of effluent composition and flow is impossible to predict and generally depends on the type of
production method used and the manufacturing breakdowns suffered. Wastewater treatment plant operators find it difficult to
maintain the efficiency of biological treatment processes. This paper focuses on activated sludge treatment modelling of paper
mill wastewater to provide operators with additional support. Based on both standard activated sludge models (ASM) and those
specific to pulp and paper, a number of relevant modifications are put forward so as to easily identify model parameters and
obtain a validated model from the dynamic data available. Model validation is performed at a pilot plant fed with industrial
effluent. Dynamic steps are applied to the process inputs (flow rates and concentrations), which induces dynamic behaviour in
the biological reactor. Measurement uncertainties are taken into account in both the identification and validation steps, while the
confidence ranges for the parameters identified are estimated. Significant biological activity is indicated by the high values
obtained for the parameters identified, which is confirmed by model validation. Because the size of the pilot plant is sufficient to
reproduce realistic hydrodynamics, the validated model accurately describes a treatment plant's behaviour and can be used by
operators as a decision-support tool.