Efeito da taxa de carregamento sobre a remo o de poluentes de esgoto em sistemas alagados construídos Effect of loading rate on removal of pollutants from wastewater in constructed wetlands

Objetivou-se estudar o efeito da taxa de carregamento sobre a eficiência de sistemas alagados, construídos de escoamento horizontal subsuperficial (SAC-EHSS), em remover poluentes de esgoto sanitário. Os SAC-EHSS foram alimentados com efluente proveniente de tanque séptico, sob taxas de carregamento organico volumétrico (TCO V) de 53 a 231 g m-3d-1 de demanda química de oxigênio (DQO total) e as associadas taxas de carregamento (TC V) de demanda química de oxigênio solúvel, sólidos suspensos totais (SST), nitrogênio total (N-Total) e fósforo total (P-Total). Para avalia o de desempenho dos SAC-EHSS, as mesmas variáveis foram quantificadas em seu efluente. Rela o linear e positiva foi obtida entre as taxas de remo o de DQO total, DQO solúvel e SST, e as TC V, nas faixas em que foram aplicadas, além de n o terem sido observados efeitos negativos desta variável sobre a eficiência na remo o desses poluentes. As taxas de remo o de N-Total e P-Total n o apresentaram, entretanto, tendência de aumento com a TC V aplicada nos SAC- EHSS, cultivados com taboa e utilizados no tratamento de efluente sanitário. As cargas aplicadas desses nutrientes devem ser consideradas referenciais no dimensionamento desses sistemas, caso se queira maximizar a remo o global de poluentes da água residuária. This research aimed to study the effect of loading rate on the efficiency of constructed wetlands with horizontal subsurface flow (CW-HSSF) to remove pollutants from wastewater. The CW-HSSF were fed with effluent from septic tank under volumetric organic loading rate (OLR V) of 53 to 231 g m-3d-1 of chemical oxygen demand (total-COD) and associated loading rates (LR V) of soluble chemical oxygen demand (soluble COD), total suspended solids (TSS), total nitrogen (total-N) and total phosphorus (total-P). To evaluate the performance of CW-HSSF the same variables were quantified in its effluent. Linear and positive relationship was found between the removal rates of total COD, soluble COD and TSS and the LR V, within the application range, and no negative effects on this variable in removal efficiencies of these pollutants. The removal rate of total-N and total-P did not show, however, tendency to increase with the LR V applied in the CW-HSSF planted with cattail and used in treating sanitary sewage. The loads applied of these nutrients must be considered referential in sizing these systems, if desired to maximize the overall removal of wastewater pollutants.