Nutrient removal by different plants in wetland roof systems treating domestic wastewater

This study evaluated nutrients removal from domestic wastewater by five plants in wetland roof systems (WR). The study plants include Arachis duranensis (1), Evolvulus alsinoides (2), Cosmos Bipinnuatus (3), Cyperus alternifolius Linn (4), and Philodendron hastatum (5). The WRs were acclimatized at hydraulic loading rates (HLR) of 220 m(3)/ha d and operated at HLR of 300 m(3)/ha d. The plants (1), (2), (4), and (5) had the ability to grow under the rooftop conditions with domestic wastewater as a nutrient source while the plant (3) was not suitable and dead after 20 d of operation. Generally, A. duranensis (1) and C. alternifolius Linn (4) were the most suitable plants treating domestic wastewater under the conditions of WR. The average phosphorus removal efficiencies of (1) and (4) were approximately 75 and 89%, respectively, while the average nitrogen removal efficiencies were 69 and 92%. The phosphorus accumulation in plants (1) and (4) during operation was 20.4 and 29.4%, respectively, while the nitrogen accumulation was 21.5 and 93%. It is concluded that C. alternifolius Linn (4) has best nutrient removal among the study plants under the conditions of shallow bed WR treating domestic wastewater (24 +/- 4 and 2.0 +/- 0.4 kg TP/ha d).