Warm season performance of horizontal subsurface flow constructed wetlands vegetated with rice treating water from an urban stream polluted with sewage

摘要

The performance of horizontal subsurface flow constructed wetlands vegetated with rice (Oryza sativa?L.) was investigated in Campina Grande (7o 13' 11" S; 35o 52' 31" W; 550 m above mean sea level), Paraíba state, northeast Brazil.?The pilot-scale system comprised 24 circular tanks (76.80 cm diameter, 54 cm height) batch fed daily with water from a nearby urban stream polluted with sewage. Experimental units were filled with substrate of either sand or gravel and operated under hydraulic retention times of 5 and 10 days.?Constructed wetlands demonstrated a very good performance in removing organic matter, fecal indicator microorganisms and nutrients from the influent representing a good alternative for the improvement of water quality of urban and peri-urban water resources. Vegetation was found to be the most important factor affecting their performances being the changes in both substrate and hydraulic retention time investigated herein of minor influence.