Abstract:
In Arba Minch Ethio Fishery condominium, domestic wastewater generated from
residential houses is often drained into rivers and streams without treatment after septic
tank. As result the environment is exposed to foul smell and potential health hazard. In
order to identify solution to the problem, the objective of this study focus on the
pollutant removal efficiency of planted horizontal subsurface flow constructed wetlands
in pilot scale. For the purpose the this study four pilot scale horizontal subsurface flow
constructed wetland units were built from concrete and planted with Phragmites
australis, Typha latifola, Eleocharis palustris and keeping one by control unit. Each CW
has a rectangular shape with inlet and outlet zone, filled with washed construction gravel
of 28-37.5mm diameter, while the main bed was filled with 10-20 mm diameter sized
gravel. The planted horizontal subsurface flow constructed wetland showed considerable
potential for removing major pollutants (TSS, BOD5, ammonia-N, nitrate-N and
phosphorus) from condominium wastewater than the control (unplanted). No significant
differences were observed among P. australis, E. palustris and T.latifolia performance
with regards to their purification ability; however, E. palustris showed higher percentage
removal efficiency in NO3-N (89%), (88%) for NH3
--N and for PO4
3--P (66.1%). The
effluent concentration values of BOD5, TSS, nitrate-N, ammonia-N and phosphorus
from the constructed wetland achieves the discharge limit set by Ethiopia National
Environmental Quality Standard for domestic wastewater. This is promising to be used
as an efficient waste water treatment system for condominium houses. There is also a
reuse option for irrigation and Gardening .
