RESUMO
Many different species of cyanobacteria capable of producing saxitoxins have been identified as a threat to the safety of drinking water supplies worldwide. Removal of these contaminants can be accomplished by adsorption on granular activated carbon (GAC) but little is yet known about the kinetics of this process. This research investigated adsorption kinetics and diffusion behaviour of decarbomoyl saxitoxin (dc-STX) and carbamate saxitoxin (STX) on a GAC sample and simulated a full-scale GAC filter using batch experimental data and the homogeneous surface diffusion model (HSDM). HSDM was able to successfully describe batch adsorption of STX and dc-STX onto GAC sample and the surface diffusion coefficient was identified as the main adjustment parameter for this model. Different scenarios of STX and dc-STX removal in a GAC filter were simulated, offering engineers and scientists an option for the design of GAC full-scale filters, bench or pilot-scale experiments.