Implantação e avaliação de wetlands construídos verticais para o tratamento de lodo de tanque séptico

Abstract

Septic tanks are treatment units for domestic sewage that are widely used in the country. They are designed to retain and treat sewage for a certain period of time. However, this treatment generates a by-product – sludge – which must be periodically removed from the tank and sent for treatment, as it contains organic matter, nutrients and pathogenic organisms – harmful to the environment. Thus, we tried to evaluate the performance of vertical constructed wetlands (WCV) for the treatment of sludge from a septic tank. Six WCVs were deployed, acting at different saturation heights at the bottom (20 cm and 10 cm) and different loadings of total solids (15, 28 and 42 kg of ST/m².year). In addition, each wetland had 0.0177 m² of surface area and 50 cm of media height. The units with the highest saturation (20 cm) showed the best average efficiencies for removal of ST, COD, NTK and P-PO43-, of 80%, 93%, 98% and 97%, respectively. Furthermore, the operation with a saturation level of 20 cm and load of 42 kg of ST/m2.year showed potential for application in new researches, notably in the northwest region of Rio Grande do Sul, as it allowed high efficiencies and resulted in lower demand area when compared to the other conditions tested in this work.