Contaminant removal in a constructed wetland for industrial wastewater treatment.

MAINE, M.A.; HADAD, H.R.; SÁNCHEZ, G.C.; CAFFARATTI, S.E.; PEDRO, M.C.; MUFARREGE, M.M.; DI LUCA, GISELA; BONETTO, C.

Barcelona

Congreso; 3rd Wetland Pollutant Dynamics and Control, WETPOL; 2009

Constructed wetlands (CW) are often used for nutrient and organic matter retention in domestic and municipal sewage, storm water and agricultural runoff (Kadlec et al., 2000). The application of CW for industrial wastewater treatment is a promising alternative in Argentina, because the central and northern areas of the country have mild winters, allowing extended growing periods for plants, and the low population density determines the availability of marginal land around cities. A free water surface wetland was constructed at Bahco Argentina metallurgic plant, in Santo Tomé, Argentina. It has been in operation since 2003. The wastewater receives a primary treatment. However, it contains Cr, Ni and Zn and shows high pH and conductivity. An assemblage of locally common macrophytes was transplanted. Vegetation was initially dominated by Eichhornia crassipes (water hyacinth), but later replaced by Typha domingensis (cattail), since the end of the first year of operation. Efficient metal and nutrient retention throughout the first stages of vegetation development has already been reported (Maine et al., 2009). Sediment and biomass metal concentrations at the inlet increased significantly, giving raise to the question whether removal could be sustained on a long term basis. Standing dry shoots are harvested and superficial bottom sediments are pumped out in the inlet area by the end of each winter. The present contribution reports metal and nutrient retention in the last years of operation, when the vegetation was stabilized, and compares it with the retention at the initial vegetation development.