Modeling of sorption of bisphenol A in sludge obtained from a membrane bioreactor process

Abstract

This work deals with the modeling of bisphenol-A (BPA) adsorption in sludge obtained from an immersed membrane activated sludge process. Batch experiments were carried out in Erlenmeyer shake flasks containing either activated sludge or inactivated sludge (200 mL of sludge at 15 g L −1 of suspended solids) in the presence of different BPA concentrations (0.45–18.2 mg BPA L −1) in order to distinguish physicochemical sorption and biosorption processes. Then, mathematical models were applied to describe the sorption phenomenon followed by the determination of kinetic of BPA removal. The applicability of the Langmuir isotherm for BPA removal allowed determining the adsorption rate constant ( K L = 0.370 L g −1) and the maximum adsorption capacity ( q m = 0.833 mg g −1). The Elovich kinetic model which takes into account of the instantaneous sorption described very well the process. The reaction rate constant for BPA removal was 0.194 g mg −1 min −1. The relatively low enthalpy value (Δ ad H° < 200 kJ mol −1) indicated that during adsorption process, very low interactions occurred between BPA and sludge, such as Van Der Waals attraction or electrostatic strengths.