Horizontal subsurface flow constructed wetlands as post-treatment of aerated pond effluent

Constructed wetland is an alternative sewage treatment based on natural solutions, which can be applied as posttreatment of wastewater from conventional processes producing an effluent with excellent properties. In this study, over a period of 300 days, the removal of organic matter and nutrients (Nitrogen and Phosphorus) at different hydraulic retention times (2, 4 and 6 days) was evaluated. Three constructed wetlands with horizontal subsurface flow planted with Eleocharis sp. were operated as after-treatment of an aeration pond, which received municipal wastewater. Constructed wetland with the highest hydraulic retention time (6 days) was the one that obtained the best results in terms of organic matter (above 60%) and nutrients removal, reaching 74% of total phosphorus removal and 73% of total nitrogen removal. It was concluded that using constructed wetlands as posttreatment of aerated pond effluents proved to be promising as it enabled the maximization of nitrification due to the high presence of dissolved oxygen available in the bed, in addition to allowing the removal of organic matter and reaching high levels in removing nutrients. [GRAPHICS] .