Humedal de flujo vertical para tratamiento terciario del efluente físico-químico de una estación depuradora de aguas residuales domésticas

Abstract

In this study two subsurface vertical flow constructed wetlands were operated and fed with the effluent of physical-chemical process of a municipal wastewater treatment plant, one was planted with the specie Iris pseudacorus (HFV2), and the other one unplanted any kind of vegetation (HFV4). The beds had a depth of 0.80m and were filled with (in cm): 20 coarse-sand, 10 peat moss, 40 fine-gravel and 10 gravel. Three experimental stages were developed with the next hydraulic load (HL): 4.2; 8.3; and 16.6 cm/d (chronological order). The process was evaluated since the steady state was reached. The average removal of COD of the planted wetland with I. pseudacorus was about 81%, whereas into the unplanted substrate was of 68%. This removal of COD was kept constant and was independent of the hydraulic and organic loads. The removal of NH4-N ranged between 75% and 96% in the HFV2, and from 66% to 83% in the HFV4. The high ammonia removal was obtained for the smallest hydraulic load. In the first two phases the performance in removing suspended solids was very low. Most suspended solids removal was observed with maximum hydraulic load that was the last of the series. This suggests that the bed porosity was lost, increasing the efficiency of retention of suspended solids by filtration.