Variações na DQO de águas residuárias da suinocultura em tratamento em sistemas alagados construídos, cultivados com diferentes espécies vegetais.

Abstract

In the wetlands (SACs), the water is purified by physical, chemical and biological mechanisms. The biological treatment is given by the contact of the residuary water with the surface of the substratum and roots, concentration sites of the bacterial biofilm, besides the transformations and absorption proportionated by the roots of the plants in growth at the system. This work’s objective was to evaluate the space behavior, time spent and the removal efficiency of the COD of the ARS in 5 SACs of 24 m x 1,1 m, with layer of 0,4 m of gravel zero. In the treatments named SAC1, SAC2 and SAC3 were planted cattail (Typha latifolia L.), Alternanthera philoxeroides and tifton 85 (Cynodon dactylon Pers.), respectively; in the SAC4, was planted in the 1º third alternanthera, in the 2º cattail and in the 3º tifton 85. The SAC5, without plants, served like control. In the 7 months of the system monitoration, an average removal of organic material (COD) of 92% was obtained at SAC4 and 88% at SAC1; moreover, the SACs had kept certain constancy in the effluent levels of COD, independent of the affluent organic charge variations. The almost totality of the COD reduction of the ARS occurred in the first 8 meters of length of the SACs.