Constructed floating wetland for the treatment of domestic sewage: A real-scale study

A constructed floating wetland using macrophytes Typha domingensis Pers. was applied to the treatment of raw sewage in a municipal sewage treatment plant in south Brazil. During 12 months, the average removal of organic matter was evaluated by chemical oxygen demand (COD), 5-day biochemical oxygen demand (BOD5) and by total suspended solids (TSS) analysis and a removal efficiency of 55, 56 and 78% was, respectively, obtained. For nutrients, total Kjeldahl nitrogen (TKN) was reduced in 41% and total phosphorus, in 37%. The floating mats supported satisfactorily the macrophytes. This floating arrangement was applied as a single step on the sewage treatment. It is an effective alternative in Brazilian sewage treatment systems, where wetlands are normally used as a polishing step. The evaluation of parameters in the treatment system may give useful information in order to improve the removal efficiency and increase the quality of the water bodies.