Artificial wetlands are low cost-technology wastewater treatment system and
could be introduced as secondary or tertiary step in the treatment system. To study
the performance characteristics of these systems, Two Gravel Bed Hydroponic pilot-
scale systems (GBH) were made of iron sheets (4mm thickness) with dimension of
4m long, 30cm width and 40cm high, provided with three tapes for controlling inlet
flow, effluent drain and system sewage depth (SO). Both units were lined with
bitumen; filled with gravel aggregates, cultivated with papyrus rhizomes and irrigated
for two month with tap water for plant growth and system establishment. The SO of
the first and the second systems were designed to operate at 10 and 20 cm sewage
depth (SO), respectively. After this period, both GBH models were fed with primary
treated wastewater from Zenien wastewater treatment plant in a batch mode.
Removal efficiencies of SS, COD, BOD, nitrogen forms and indicator microorganisms
under different retention times of 4, 8, 12, 16 and 24 hrs were studied. Results were
deeply discussed.