The objective of this study was to evaluate the effect of adsorption on the biological treatment process of
wastewater. In the absence of substrate in the water, activated sludge developed well in the first hour,
indicating that the growth of microorganism was not directly related to substrate concentration and
the dissolved organic matter in the water assays were performed, no organic matter was detected out,
revealing that there was no desorption in the activated sludge adsorption process. Activated sludge batch
growth experiments in the presence of different adsorption capacities indicated that specific growth rate
increased as specific adsorption capacity increased. The experiment on the relationship of adsorption
capacity and substrate concentration or sludge concentration was also carried out. Specific adsorption
capacity increased as sludge load increased, presenting linear correlation. The experiment results showed
that adsorption should be taken into account in the study of the biological treatment process of
wastewater.