Multiresponse parameter estimation of SVOCs in activated sludge process

Semivolatile organic chemicals (SVOCs) in a treatment system may be dissolved in the liquid phase, adsorbed into the solid phase, become part of the gaseous phase, or be biologically degraded. Experiments on discovering their fate should examine these phases simultaneously. As a result, the experiments produce multiple responses relating the liquid, solid, and gaseous phases of the system. These data are used to estimate parameters (e.g., rate constants) for biodegradation, volatilization, adsorption, and perhaps desorption. This paper explains how data were collected in unsteady-state experiments and how the multiple-response nonlinear least-squares parameter estimation was done on a set of simultaneous differential equations. Some aspects of the model building process, parameter significance and consistency, and model simplification are also discussed.