In the biological activated carbon (BAC) filters at the water treatment plant Weesperkarspel of
Waternet, water cycle company for Amsterdam and surrounding areas, rapid clogging takes place.
A pilot plant study was carried out to study the processes responsible for the clogging. Several
hypotheses were tested, including clogging due to biomass and calcium carbonate particles
origination from the pellet softening. Results show that the clogging is a combination of several
factors. Clogging by biomass results in the formation of a cake layer which accounts for the
majority of the pressure build-up. The data collected during the pilot plant study were used to
calibrate and validate a model for predicting the pressure drop in the filters. The model predicts the
filter run time based on the influent water quality of the BAC filters. The model can be used to
optimize the backwash sequence, resulting in a reduction of the use of backwash water. Includes 19 references, tables, figures.