Wetland constructed for metal removal faced with a depredation event.

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

Perth

Conferencia; 13th International Conference Wetland Systems for Water Pollution Control. IWA-; 2012

IWA_ Murdoch University

A free water surface constructed wetland (CW) was dominated by the emergent macrophyte Typha domingensis for 5 years. Highly efficient metal and nutrient removal from metallurgical effluents was reported during this period. In June 2009, capybaras caused the complete depredation of the aerial parts of macrophytes. After depredation stopped, T. domingensis reached a cover of 60 % in 30 days. The objective of this work was to evaluate the sustainability of the CW subjected to an extreme event. Removal efficiency was compared during: normal operation, depredation event and the subsequent recovery period. The CW efficiently retained contaminants during all the periods studied. The best efficiencies were registered during the normal operation period. There were no significant differences between the performances of the CW over the last two periods, except for BOD. Despite the anoxic conditions, contaminants were not released from sediment. T. domingensis showed an excellent growth. Plants continued retaining contaminants and the sediment increased its retention capacity, probably due to the CW had reached its maturity. These results demonstrated that faced with an incidental problem, this mature CW was capable of maintaining its efficiency and recovering its vegetation, demonstrating the robustness of these treatment systems.