Treatment performances of floating wetlands: A decade of studies in North Italy

Floating treatment wetlands (FTWs) are one of the most recent eco-technologies to treat low-quality polluted wastewaters in already existing retention ponds, without subtracting other soil surface for the treatment of wastewaters. This study assessed the depuration performances of eight different FTWs (1 pilot-scale and 7 full-scale plants) treating municipal wastewaters, agricultural runoff and digestate liquid fraction, in North Italy. The concentration of different pollutants was monitored before and after the FTWs barriers: total nitrogen (TN), nitrate nitrogen (NO3-N), ammonia nitrogen (NH4-N), total phosphorus (TP), orthophosphate (PO4-P), chemical oxygen demand (COD) and turbidity. Considering all the case studies, pollutants inflowing concentrations were highly variable, due to the different composition of wastewaters used in the trials (TN: 0.3–520.0 mg L−1, median value 19.1 mg L−1; NO3-N: <0.001–61.5 mg L−1, median value 2.6 mg L−1; NH4-N: <0.001–310.0 mg L−1, median value 3.6 mg L−1; TP: 0.02–44.9 mg L−1, median value 5.7 mg L−1; PO4-P: