In order to study the relationship between Wastewater Oxidation Ponds efficiency and maturation ponds ecological communities, two AGERE systems from Braga neighbouring villages were selected: Cabreiros, CAB and Tebosa, TEB. Every two weeks sampling campaigns were realized (March - July 2007) to gather wastewater simple samples at the systems inflow and outflow. Determinations of Biochemical and Chemical Oxygen Demand and Total Suspended Solids (BOD5, COD and TSS mg/L), Recovered Heterotrophics and Total and Fecal Coliforms (RH, TC and FC, CFU ml/L) were performed at UM-Biology Lab. The removal efficiencies were 10% higher at CAB for BOD5 and COD and 10% higher at TEB for TSS. RH removal
was mostly higher than 95%, but on CAB 6 and 9 samples, was respectively null and weak. During almost all the sampling period TC and FC removal were about 100% at both systems, but on samples 6 and 9, TC and FC CFU/ml were higher at CAB outflow than at inflow. Samples from maturation ponds were also gathered and maintained in the lab for a month, as microcosms. The daily microscopic analysis showed that in CAB maturation pond Euglena, Scenedesmus and diatoms are generally predominant whereas in TEB maturation pond the constant presence of Lemna was concomitant with a lesser density and diversity of algae. The samples 6 and 9 from CAB maturation pond, showed an absence of eucaryotic heterotrophics probably associated with the weak or even null removal of TC and FC
