Treatment performance and macrophytes growth in a restored hybrid constructed wetland for municipal wastewater treatment

tThis work evaluated depuration performance and macrophyte plants growth in a full-scale hybrid-constructed wetland (H-CW) (1000 population equivalent) treating municipal wastewater. The plantwas activated in June 2010 after a restoration of an existent H-CW composed of a horizontal subsur-face flow (HSSF) bed vegetated with evergreen xerophile species (Prunus laurocerasus, Pittosporum spp.,Elaeagnus angustifolia), connected with a sedimentation pond vegetated with Lemna spp. To enhancethe depuration performances, in both sections of the plant the original vegetation was removed and theHSSF bed was vegetated with Phragmites australis, whereas in the pond, a floating treatment wetland veg-etated with Iris pseudacorus was installed. The depuration performance in treating total nitrogen (TN),nitrate nitrogen (NO3-N), ammonia nitrogen (NH4-N), total phosphorus (TP), orthophosphate (PO4-P) andchemical oxygen demand (COD) was weekly monitored between August 2010 and August 2011. Resultsindicated median concentration abatements for the entire system of 74.3% for TN, 62.1% for NH4-N, 77.7%for NO3-N, 29.6% for TP, 37.4% for PO4-P, and 46.7% for COD. In addition, at the end of the first growingseason (June 2010–November 2010), good adaption to the system was detected for both P. australis andI. pseudacorus, which produced respectively 3.9 ± 2.2 kg m−2and 3.7 ± 1.0 kg m−2of above-ground drybiomass, with average above-ground N uptakes of 62.4 ± 35.6 g m−2and 69.8 ± 19.0 g m−2and averageabove-ground P uptakes of 4.6 ± 2.6 g m−2and 7.8 ± 2.1 g m−2. The results indicate that a H-CW composedof a sequence of HSSF bed and FTW represents an effective application for abating TN, NH4-N, NO3-N andCOD concentrations from municipal wastewater.