Variance-based sensitivity analysis for wastewater treatment plant modelling.
Global sensitivity analysis (GSA) is a valuable tool to support the use of mathematical models that characterise technical or natural systems. In the field of wastewater modelling, most of the recent applications of GSA use either regression-based methods, which require close to linear relationships between the model outputs and model factors, or screening methods, which only yield qualitative results. However, due to the characteristics of membrane bioreactors (MBR) (non-linear kinetics, complexity, etc.) there is an interest to adequately quantify the effects of non-linearity and interactions. This can be achieved with variance-based sensitivity analysis methods. In this paper, the Extended Fourier Amplitude Sensitivity Testing (Extended-FAST) method is applied to an integrated activated sludge model (ASM2d) for an MBR system including microbial product formation and physical separation processes. Twenty-one model outputs located throughout the different sections of the bioreactor and 79 model factors are considered. Significant interactions among the model factors are found. Contrary to previous GSA studies for ASM models, we find the relationship between variables and factors to be non-linear and non-additive. By analysing the pattern of the variance decomposition along the plant, the model factors having the highest variance contributions were identified. This study demonstrates the usefulness of variance-based methods in membrane bioreactor modelling where, due to the presence of membranes and different operating conditions than those typically found in conventional activated sludge systems, several highly non-linear effects are present. Further, the obtained results highlight the relevant role played by the modelling approach for MBR taking into account simultaneously biological and physical processes.
Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali - Università di Palermo, Viale delle Scienze, 90128 Palermo, Italy. Electronic address: alida.cosenza@unipa.it.
Alida
A
Cosenza
Dipartimento di Ingegneria Civile, Ambientale, Aerospaziale, dei Materiali - Università di Palermo, Viale delle Scienze, 90128 Palermo, Italy. Electronic address: giorgio.mannina@unipa.it.
Giorgio
G
Mannina
modelEAU, Département de Génie Civil et de Génie des Eaux, Université Laval, 1065 av. de la Médecine, Québec, QC G1V 0A6, Canada. Electronic address: Peter.Vanrolleghem@gci.ulaval.ca.
Peter A
PA
Vanrolleghem
modelEAU, Département de Génie Civil et de Génie des Eaux, Université Laval, 1065 av. de la Médecine, Québec, QC G1V 0A6, Canada; Basque Centre for Climate Change, Alameda Urquijo, 4 - 4°, 48008 Bilbao, Spain; IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain. Electronic address: marc.neumann@bc3research.org.
Marc B
MB
Neumann
D008962:Models, Theoretical; D012722:Sewage / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*; D062065:Wastewater / Q000737:chemistry* / Q000382:microbiology
D012722:Sewage; D062065:Wastewater
Extended-FAST; Global sensitivity analysis; MBR modelling; Wastewater treatment