An investigation of the pathogenic and non-pathogenic free-living amoebae from the root zone method of wastewater treatment

Pathogenic and non-pathogenic free-living amoebae from the Root Zone Method (RZM) of wastewater treatment were investigated. Ten reed beds planted on four different substrate types were compared for their efficiency of removal of free-living amoebae. Reed beds planted on coarse substrates generally gave the highest removal rates (up to 100%) while those planted in soil gave the lowest (60.4%). Possible reasons for differences in removal efficiencies are discussed. Thirteen species representing nine genera of free-living amoebae were isolated; these included three species of Acanthamoeba (A. astronyxis, A. polyphaga and A.rhysodes) all of which were pathogenic for mice. The implications for RZM design of the presence of potentially pathogenic free-living amoebae in the effluent are discussed.