Nonlinear parameter estimation of nonylphenol biodegradation

The use of surfactants to enhance the aqueous of hydrocarbons has been investigated extensively. Addition of surfactants, detergents and emulsifiers has been successfully applied for cleanup of petroleum-contaminated sites. However, recently a certain group of widely used alkylphenolethoxylates (APE) surfactants was banned in Europe because their breakdown products are estrogenic and highly toxic to aquatic organisms. However, very little information is available on the biodegradation kinetics of nonylphenol. Kinetic information is necessary for predicting the fate of pollutants using mathematical models. This paper presents system identification results using nonlinear optimization. By using nonlinear regression methods such as nonlinear least squares, one can obtain the biodegradation kinetics. The paper demonstrates the expectations and the feasibility of results from such a nonlinear process