Stefano Marsili-Libelli

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The parameters of ecological models are usually estimated through numerical search algorithms. Determining confidence boundaries for the parameter values obtained in such a way is a problem of great practical importance. In this paper a method is proposed to estimate such regions in two ways, based on either the Hessian matrix or the Fisher Information(More)
The sequencing batch reactor (SBR) is a widely used process for biological removal of nutrients (nitrogen and phosphorus) from wastewater. It is based on the metabolism of specialised bacteria, which under alternate anaerobic/aerobic conditions uptake phosphorus and perform denitrification. Intermittent operation is normally operated on a fixed switching(More)
The present paper reports the results of the application of a control system, based on artificial intelligence concepts, for the automation of a bench-scale SBR treating leachate generated in old landfills. Attention was given to the nitritation and denitritation processes in order to enhance the nitrogen removal efficiency. Nitrification and nitrogen(More)
When modelling a biochemical system, the fact that model parameters cannot be estimated exactly stimulates the definition of tests for checking unreliable estimates and design better experiments. The method applied in this paper is a further development from Marsili-Libelli et al. [2003. Confidence regions of estimated parameters for ecological systems.(More)
This paper discusses the application of artificial intelligence (AI) concepts to the monitoring of a lab-scale Sequencing Batch Reactor (SBR) treating nitrogen-rich wastewater (sanitary landfill leachate). The paper describes the implementation of a fuzzy inferential system to identify the correct switching sequence of the process and discusses the results(More)
A common limitation of the Activated Sludge Models (ASM) [Henze, M., Gujer, W., Mino, T., van Loosdrecht, M.C.M., 2000. Activated Sludge Models ASM1, ASM2, ASM2d, and ASM3. IWA Scientific and Technical Report No. 9. IWA Publishing, London, UK] is the representation of the nitrification dynamics as a single-step process and the consequent denitrification on(More)
Water quality modelling in small rivers is often considered unworthy from a practical and economic viewpoint. This paper shows instead that a simple model structure can be set up to describe the stationary water quality in small river basins in terms of carbon and nitrogen compounds, when the use of complex models is unfeasible. In short rivers point and(More)
The aim of the paper is to assess the experimental errors arising from the operation of a closed respirometer using autotrophic biomass. A closed, intermittent-flow device has been set-up for the measurement of oxygen uptake rate (OUR) and parameter calibration. After describing the device structure and operation, the factors affecting accuracy have been(More)