Abstract:
Constructed floating wetland (CFW) has been a popular phytoremediation based water
treatment method for water purification purposes since the turn of the century. Natural
macrophytes form floating hydroponic mats on the water’s surface and a root system
that acts as a natural filter. This study was conducted at Horana Export Processing
Zone to evaluate the potential use of floating wetland plants of Cyperus iria, Heliconia
psittacorum and Canna indica for removing pollutants from wastewater. The CFW
unit (size of 0.75 m Ö 0.46 m Ö 0.15 m (LÖWÖH)) was made with coconut husk chips,
rice hulls, and soil media. Triplicate CFW with varying plant densities and three units
without plants as control treatment were established in 90 L tanks. Water samples were
collected over an 8 week period for analysis. Water quality parameters (BOD, COD,
TSS, TDS, Nitrates, Phosphates and Heavy metals (Pb, Cr, Ni)) were measured once
a week. One Way ANOVA Repeated measure analysis (95% confidence interval) with
Tukey’s Post Hoc Test was carried out. Canna indica showed high removal efficiency in
TSS, COD, Cr, Ni and nitrates as 58.1%, 73.0%, 72.0%, 86.6%, and 59.5%, respectively.
Cyperus iria showed high reduction efficiency in BOD (56.7%) and phosphates (87.2%).
Heliconia psittacorum showed high reduction efficiency in TDS (71.6%), Pb (58.0%).
The results of the study suggested the selected Cyperus iria, Heliconia psittacorum,
Canna indica could be potential plant species used in the CFW system to improve
treated wastewater quality.
