Introducción

The objective this work was the study of the removal efficiency of helminthes eggs in a Combined System of Treatment made up by two reactors UASB and Lagoons of Stabilization on pilot scale. The system was located in the Sewage Treatment Plant in the city of Salta (Argentina). The analyses were carried out with 19 samples, during the period May-November of 2002. In the Reactor 1 parasites eggs removal was 83% during the winter and 92 % in the summer. In Reactor 2 removals were low, probably due to unsuitable sludge shape. The removals in stabilization ponds were of 77 % and 96 % in the respective periods. Total removal of helminthes eggs in the system was 99.3 % in the winter period and 99.7 % in the summer period turning out to be an attractive option for the treatment of sewage in subtropical regions.