Treatment of domestic wastewater in a pilot-scale natural treatment system in central Mexico

There is severe degradation of the water quality of the Texcoco River in central Mexico as a result of discharges of raw sewage from communities into the watershed. Constructed wetlands may be appropriate technologies for treating the domestic wastewater Generated by small communities in central Mexico. To assess the removal of pollutants from wastewater, we constructed a pilot-scale treatment wetland in the small community of Santa Maria Nativitas in the Rio Texcoco watershed. The system, consisting of sedimentation terraces, stabilization pond, subsurface flow wetland (SSFW) and vertical flow wetland (VFW), removed > 80% of TSS. COD and nitrate from domestic sewage. Removal of ammonium was less efficient at about 50%. This study also showed that ornamental flowers with high economic value planted in the SSFW performed as well as cattail (Typha angustifolia) in removing TSS and nitrogen. The treated water was suitable for irrigation, which could help to alleviate the scarcity of water in the Rio Texcoco watershed. Modeling exercises indicated that the pilot-scale wetland could be readily adapted to treat sewage from six families. (c) 2004 Elsevier B.V. All rights reserved.