A mathematical model of deep-bed filtration has been calibrated and verified based on experimental results. The experimental system, used for testing of the secondary treatment quality and the tertiary filtration phase, incorporates an SBR system followed by a filtration column. The turbidity of the incoming SBR effluent was in the range of 12 to 34 NTU. The bed grain size was in the range of 1.4 to 2.0 mm. The examined filtration velocities were 11, 15, 20 and 25 m/h. The filtration process is simulated by equations of balance and kinetics. The latter includes the attachment and detachment process, characterized by rate coefficients KA and KD, respectively. These coefficients , as well as the parameters of hydrodispersivity and effective porosity, are found on the basis of nonlinear optimization, using numerical solution of the model and the experimental breakthrough curves. The method demonstrates good agreement between experimental and simulated results.