Caracterização de lagoas de estabilização profundas - lagoas facultativas primárias.

Abstract

The aim of this study is to characterize deep waste stabilization ponds, specially primary facultative ponds treating sewage. To carry out this research,fourindependently loaded deep primary facultative ponds with surface loads varying from 193 to 290 Kg DOB5.ha -1 . d - 1 were investigated. These pilot scale ponds (.with mean depth of 2.30 m) were builtat EXTRABES (Estação Experimental de Tratamentos Biológicos de Esgotos Sanitários), Campina Grande, Paraíba, Brazil (7°13'11"S, 3 5 0 5 2 ' 3 1 " W ) . Duringv.the experimental period (20/11/85 to 2 5 / 0 4 / 8 6 ) , the parameters pH , temperature, dissolved oxygen, chlorophyll a, algae Identification and counting were investigated throughout the depth of the ponds. It was found out that deep ponds showed during the light hours and near the surface (up to nearly 25 cm bellow the surface)', high concentration of dissolved oxygen anl chlorophyll a, high pH values, a well defined vthermal stratification and the predominance of motile algae [Euglena, Pyrobotys and Chlamydomonas) . In contrast, the bottom layers and at night along the whole water column, anaeróbic conditions, pH values near neutral , low concentration of chlorophyll a, uniform values of temperature.and presence of both motile and non motile genus of algae were ohserved.