Performance of Wetland Roof Treating Domestic Wastewater in the Tropic Urban Area

This study evaluated the treatment efficiency of four plants, namely Axonopus compressus (2); Melampodium paludosum (3); Tradescantia spathacea compacta (4); Catharanthus roseus (L) G. Don (5), in the wetland roof system (WR). Five WRs (including the control system) were operated at the two hydraulic loading rates (HLR1 of 220 m 3 /ha.day and HLR2 of 417 m 3 /ha.day), corresponding to organic loading rates (OLR1 of 31 kg COD/ha.day and OLR2 of 71 kg COD/ha.day). The studied plants had the ability to grow in the roof conditions with domestic wastewater as a nutrient source. The removal efficiencies (mean ± SD) of the control (1), (2), (3), (4), (5) were approximately 55 ± 4; 68 ± 5; 71 ± 4; 65 ± 5 and 65 ± 10% (or 20 ± 2; 25 ± 5; 30 ± 7; 25 ± 3 and 23 ± 3 kg COD/ha.day) and 16 ± 6; 41 ± 9; 40 ± 20; 44 ± 22; 7 ± 6% (1.8 ± 0.8; 4.8 ± 0.8; 4.4 ± 2.2; 4.8 ± 2.2; 0.6 ± 0.5 g TP/ha.day) and 41 ± 5; 56 ± 3; 59 ± 4; 55 ± 7; 54 ± 9% (or 1.7 ± 0.3; 2.4 ± 0.2; 2.5 ± 0.3; 2.4 ± 0.4; 2.2 ± 0.5 kg TN/ha.day) at 192 - 247 m 3 /ha.day of HLR, respectively for COD, TP and TN. Generally, Axonopus compressus (2) and Melampodium paludosum (3) were the most suitable plants treating domestic wastewater for the conditions of WR.