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.