Different types of mathematical models have been proposed to predict the activated sludge process final effluent quality. La Motta (2004b) developed a mathematical model linking the operating parameters of an activated sludge system and the classical limiting flux sludge settling theory. This project studies the estimation of the unknown parameters of La Motta\u27s model and also the model\u27s sensibility. To obtain unknown parameters true values Full Information Maximum Likelihood (FIML) estimator is used, it will converge on a set of values that satisfy all the estimating equation simultaneously. Favorable results were obtained when correlations are applied between predicted values using estimated kinetics parameters and the observed values obtained from activated sludge pilot plant located within installations of the Marrero Wastewater Treatment Plant, New Orleans, Louisiana. Constructive results about the sensibility of the model are also obtained demonstrated that the model is affected significantly to the variation of some kinetics parameters
