Comparison of Reed and Water Lettuce in Constructed Wetlands for Wastewater Treatment.

  In the present study two designs, vertical and horizontal systems, were used and two different plant species, Water Lettuce (Pistia stratiotes) and Reed plant (Phragmites karka), compared for their removal efficiency. The vertical system appeared to be more stable and efficient for almost all the parameters. The vertical system, planted with Water Lettuce, showed percentage removal efficiency for BOD, phosphate and chloride as 82, 95.4, and 51, respectively, whereas turbidity and total suspended solids removal efficiencies were almost the same. However, fecal coliform removal by the Water Lettuce was 98.8% for both designs (vertical and horizontal), showing the ability of the plant to uptake nutrients and release toxins for pathogen disinfection. It appears that the vertical system could be the better option, planted with Water Lettuce, or with both plants in a co-culture environment.