Treatment of total petroleum hydrocarbon by free water surface constructed wetland: Effects of different combinations of submerged and free-floating plants

Submerged and free-floating plants in free water surface constructed wetland (FWSCW) play a crucial role in pollutant removal, but their combined effectiveness for total petroleum hydrocarbon (TPH) removal remains unclear. In this study, four lab-scale FWSCWs with different combinations of submerged and free-floating plants (CW1: E. crassipes and V. natans, CW2: E. crassipes and M. aquaticum, CW3: L. laevigatum and V. natans, and CW4: L. laevigatum and M. aquaticum) were established to investigate the TPH removal of FWSCW. CW4 achieved satisfactory removal of TPH and other contaminants, with a 3.15–12.5 % TPH removal efficiency improvement compared to other FWSCW. The TPH concentration in plants and total biomass in CW4 were significantly higher than those in other FWSCW (p