1. Introduction
Trickling filters offer well-known and widely applied technical solutions to treat wastewaters of different sources and compositions. Their main purpose is to provide nitrification and removal of Biochemical Oxygen Demand (BOD) [1]. Treatment
capacity is related to the total surface of the filter medium, providing area for bacterial growth. As each filter medium has a specific index of area per volume, the treatment capacity can be indi cated as mass removal per volume per time.Unfortunately, the conventional trickling filter approach does not recycle nutrients in the wastewater
but merely transforms them into non-toxic (H2O, NO3) or gaseous forms (CO2, N2) [2].