abstract
Plant species carry out a series of important biological, chemical and physical processes within a constructed wetland wastewater treatment system and make a significant contribution to wastewater
purification. This paper compares two emergent macrophytes –Cyperus alternifoliusL. andTypha latifoliaL.
– planted separately in a pilot horizontal subsurface flow systemfor the phytoremediation of treated urban
wastewater in the West of Sicily (Italy). The total surface area of the three units within the pilot system was
99 m
2
. Six subunits were planted with two species and three subunits were left unplanted as the control.
The main aim of the study was to demonstrate that, under identical hydraulic and design conditions, not
only the use but also the choice of plant species significantly influences wastewater treatment processes
with regard to all chemical, physical and microbiological parameters. The reedmace colonized a larger
surface area and produced significantly higher yields of aboveground (3221 g m
2
/year) and belowground
(4071 g m
2
/year) biomass than the umbrella sedge. Nitrogen content was also found on average to be
higher in the reedmace-based treatments (40.6 g m
2/year for aboveground and 62.7 g m
2
/year for belowground parts). A good level of BOD5removal (72.4% for reedmace and 64.8% for umbrella sedge-based
treatments) was obtained.Escherichia coliremoval efficiency did not exceed 89.5%.