Kamstra et al. (1998) reported TAN areal removal rates between 0.24 and 0.55 g TAN/m2 day for a commercial-scale trickling filter. For three different applied filter medium types in commercial farms and a range of hydraulic surface loading conditions, the highest observed TAN areal removal rate for a trickling filter was 1.1 g TAN/m2 day, with an average TAN areal removal rate of about 0.16 g TAN/m2 day (Schnel et al., 2002;Eding et al., 2006). Lyssenko and Wheaton (2006) reported TAN areal removal rates of 0.64 g TAN/m2 day. In the same study they found similar TAN areal removal rates for a submerged expandable upflow sand filter.