Clinoptilolite is a member of the heulandite group of zeolites and has the ideal formula Na-6 Al-6 Si-30 O-72. 24H(2)O. Previous studies on this zeolite have shown that it can be used as an ion-exchange resin offering a potentially economic alternative to biological filtration in the removal of ammonium ions from wastewater. This paper illustrates preliminary characteristics of clinoptilolite, i.e., composition, structure, uptake capacities and uptake rates, prior to the an evaluation of the potential enhancement of ammonia removal capacity by nitrifying bacteria colonisation.