obtained from a nursery. The system was fed with urban
wastewater from activated-sludge wastewater treatment plant
(WWTP) in Raffadali which effectuated primary and secondary
treatment of the wastewater. The treated urban wastewater from
the municipal treatment plant was fed initially into a 15m3
waterproofed, vibrated cement storage tank. The tank was
equipped with a litre gauge and an outlet valve for the periodic
cleaning of solid sediments. The wastewater was pumped through
a 1m wide perforated polyvinylchloride pipe into each of the two
units. In each unit, the pipe was placed 10cm from the surface of
the substrate. The homogeneous distribution of wastewater in
each sub-unit was ensured through a timer-controlled pumping
system. The pumping was continuous throughoutthe day without
variations in time. The units operated under the same hydraulic
conditions and were tested using a hydraulic loading rate (HLR) of
12cm/d.