Modelling competitive adsorption of organic micropollutants onto granular activated carbon in fixed-bed adsorbers for...

Adsorption of potentially toxic and persistent organic micropollutants (OMP) in granular activated carbon (GAC) fixed-bed adsorbers has become increasingly established as an advanced wastewater treatment process in recent years. To gain a deeper understanding of relevant removal mechanisms and operating conditions, this work investigates a multisolute model approach for the filter breakthrough curve (BTC) prediction of OMP and dissolved organic carbon based on the ideal adsorbed solution theory in combination with the tracer model for competitive adsorption and the linear driving force model for surface diffusion. The model was calibrated with equilibrium and kinetic batch experiments and validated based on operational data from full-scale and pilot-scale GAC filtration. Model predictions proved well for OMP removal dominated by adsorption mechanisms (benzotriazole, carbamazepine), but revealed the need to include biodegradation processes particularly for diclofenac and to further investigate the role of short empty bed contact times and desorption processes for the model performance. Implementation of filter backwashing showed an additional effect on the breakthrough curve behaviour and significantly improved model predictions for the full-scale GAC adsorber.