Comportamento de formas de fósforo em sistemas de lagoas de estabilização, em escala-piloto, sob diferentes configurações, tratando esgoto doméstico.

Abstract

This work had the objective of behavior of phosphorus forms in two systems of stabilization ponds in series (Systems XVI and XVII), in pilot scale, treating domestic sewage. The experimental systems were located in the neighborhood of Catingueira, in the dependencies of the Sewage Treatment Station (ETE) of the city of Campina Grande (7º 13 '11 "S, 35º 52' 31" 0, 550m above sea level, state of Paraíba, northeast of Brazil). System XVI consisted of two parallel anaerobic lagoons (A9 and A10), five parallel secondary facultative ponds with different geometries (F 21 to F 25), one called primary maturation pond (M15) five parallel ponds, called maturation, with different geometries (M16 to M20) and four tertiary maturation pools (M21 to M24). System XVII consisted of an anaerobic lagoon (A11) followed by a secondary facultative pond (F26) and eight lagoons called maturation (M25 to M32). System XVI was analyzed in the period from November 1991 to October 1992, based on samples from column. System XVII was analyzed during the period from January to October 1992, based on effluent and column samples. The parameters analyzed in the pond samples and in the raw affluent drain during routine monitoring were temperature, pH, dissolved oxygen, BODs, chlorophyll a, total phosphorus and soluble orthophosphate. In the period between May and October 1922 all the phosphorus fractions present in the lagoon samples of the two experimental systems were also determined. In System XVII, total phosphorus and soluble orthophosphate removals of up to 54 and 63% were observed, respectively. This performance can be attributed to the predominance of high pH values ​​and algal biomass, favoring the mechanisms of chemical precipitation and biological assimilation, respectively. In system XVII, the efficiency of removal of total phosphorus was 41%, when analyzed with effluent samples and 31% when with column samples. In this system, both the effluent and the column samples showed increases in soluble orthophosphate concentrations in relation to the raw sewage. These increases attest to the inhibition of the mechanisms of chemical precipitation and biological assimilation caused by the low pH and biomass of algae, respectively.