OPTIMAL SAMPLING DESIGN FOR A SLUDGE BLANKET INTERFACE SETTLING MODEL

An experimental design For a nonlinear sludge blanket interface settli ng model was examined. The model describes sludge settling in a batch reactor as a function of time having two parameters. The criterion app lied in detecting the minimal sampling schedule was the D-optimality. The design was constructed on the basis of the Wynn-Fedrov algorithm. The algorithm proved its validity leading to a logical result. The opt imal sampling design consists of two measurement points which is equal to the number of parameters to be estimated. This is a generally obse rved result in D-optimality and can be interpreted that in the D-optim ality the information per implemented observation is maximized. In add ition to the determination of optimal sampling schedule, the experimen tal design can be used in examining models. The two measurement paints have the same weights indicating that the parameters are equally impo rtant in the examined model. The results also show that a small change in the nominal values of the parameters have a minor effect on the ou tput of the studied model. The model output is more sensitive to the c hanges in the parameter alpha than to the changes in the parameter C. In the field of environmental engineering, model oriented observationa l design is rarely utilized, although it might be helpful in achieving better understanding of models and more effective utilization of reso urces. (C) 1997 Elsevier Science Ltd.