Adsorption of bacterial cells onto activated sludge flocs

The adsorption of 9 species of bacteria onto laboratory-activated sludge fl ocs were investigated and a kinetic model describing the adsorption process was proposed in order to design an effective bioaugmentation strategy. The typical time course of bacterial adsorption, which is a triphasic process, consisted of lag, rapid adsorption, and stationary phases. The equilibrium of the cells in the stationary phase obeyed the Freundlich isotherm. The r eversible and nonlinear model could describe the process to a certain degre e and the Freundlich parameters and specific sorption rates were estimated for each bacterial strain. There was no apparent relationship between the e stimated parameters and characteristics of the bacterial strains, such as s pecific growth rate, hydrophobicity of the cells, and flocculation activity against kaolin clays. However, the high hoc formation ability of the bacte rial strains was observed to be related to high cell concentrations althoug h a longer lag time was required.