Estudo do ciclo do nitrogênio em lagoas de estabilização tratando esgotos domésticos no Nordeste do Brasil.

Abstract

This work deals with the study of the behavior of nitrogen forms in two systems of stabilization ponds (Systems XVI and XVII), on a 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, 35 ° 52' 31" W. 550 m above sea level) , state of Paraíba, northeastern Brazil. System XVI consisted of two parallel anaerobic lagoons (A9 and AIO), five parallel secondary facultative lagoons with different geometries (F21 to F25), one called primary maturation lagoon (M15), five parallel lagoons, known as maturation with different geometries (M16 to M20) and four tertiary maturation pools (M21 to M24). The Sitema XVII consisted of an anaerobic lagoon (A11) followed by a secondary facultative pond (F2S) and eight lagoons called maturation (M26 to M32). The systems of the experimental complex were analyzed from June to December 1992. For System XVI, liquid column sampling was used in the lagoons, while in System XVII samples of column and pond effluent were used. During routine monitoring, the following parameters were analyzed in pond samples and raw sewage tributary: total Kjeldahl nitrogen, ammoniacal nitrogen. organic nitrogen. nitrate. nitrite, temperature, pH, dissolved oxygen BOD, suspended solids and chlorophyll "a". The removal of nitrogen occurred mainly in the maturation ponds p and l the mechanism of volatilization of ammonia, due to the high pH in these ponds. System XVI reached 90% ammonia removal efficiency. System XVII presented efficiencies of 77 and 71% for the effluent and column samples, respectively. The anaerobic lagoons promoted organic nitrogen around 50%. In the other reactors small changes were observed. The final concentration of organic nitrogen in System XVI was about 10 mg N / L and about 5 mg N / L in System XVII. Concentrations of nitrate enitrate were small in the reactors of the experimental complex. In System XVII the values ​​were higher than in System XVI.