Comparative Dimensions in Lake Systems and Wetlands for Sewerage Treatment in a Small Community

Abstract

Sewerage´s polluting load is removed by sewage treatment stations (STS) prior to its discharge into a receiving water body. Choice between sewerage treatment systems is the result of a comparative study applied to a small and low income 1800-strong contributing community in the municipality of Campos Novos SC Brazil. Sanitary sewerage treatment system evaluated such aspects as STS area, implantation costs, power and energy consumption, sludge production, removal of nutrients, reliability, operational leanness and usage life. The systems contemplated were Stabilizing Lakes and Root Zones or Wetlands. Whereas the former required 15,448 m2, the wetland system demanded 1,626 m2. Consequently, the stabilizing lake system was discarded within the land plot of the Samae firm and the wetland project implemented. Advantages in wetland system comprise a biologically based system without the use of electrical power, chemical products or mechanical equipments and unpleasant odors due to the plants´ filtering process. The most viable system comprises preliminary treatment, one septic tank with two chambers (18 x 7 x 2.80 m), two anaerobic filters (diameter 5.70 m; depth 2.25 m) and four wetland units (33 x 11 x 0.70 m). The developed project cost R$ 600.000,00.