Microfauna found in an activated sludge WTP was characterized, correlated to the physical-chemical parameters and used in existing assessment models. During 351 days, the activated sludge remained stable with compacted and small poorly filamentous flocs. It was composed mainly by testate amoebas and crawling ciliates that indicated the stability of the system. The application of the existent system evaluation models to microfauna (SBI, crawling ciliate/attached ciliate relation and total density) was found to be efficient for the assessment of the system depurative conditions. The sludge qualitative analysis, which included the flocs size, amount of filaments, compacting and the identification of the dominant microfauna species, was enough to an immediate diagnosis of the treatment system depurative conditions.
Microfauna; activated sludge; domestic wastewater; microscopy; treatment diagnosis
