Abstract:
Coffee processing wastewater is one of the major agro-processing wastes that put high pollution
pressure in coffee growing and exporting countries affecting water and human health .The
Mohammed Jamal’s wet coffee processing industry in Jimma apply no or low efficient
technologies for treatment due to lack of economic and technological feasibility. The aim of this
study is to investigate the nutrients removal capacity of Canna Indica based Horizontal
Subsurface Flow Constructed Wetland (HSCW) made of Gravel.The experimental set up of
constructed wetland (CW) with dimension of 2.8 m (length) ,0.8 m (wide) ,and 0.65 m(depth) has
been done at Jimma institute of Technology (JiT) .Locally available plants ,Canna Indica were
planted in two of three cells while the remaining unplanted cell served as the control .Monitoring
of wetland influent and effluent wastewater was carried out every 24 hours with in HRT of 4
day.The response surface methodology (RSM) based on central composite design was employed
for data analysis was found to be effective tool to evaluate, optimize the effect of operating
parameters on the responses, and analysis of variance (ANOVA) with 95% confidence limits was
used to determine the significant , the validation of the model, the significant of independent
variables and their interaction effect on the responses.The study revealed successful treatment of
the wastewater by the wetland in term of turbidity ,TSS,COD,NO3
-
and PO4
3-
effluent compliance
with world health organization (WHO) discharge standards except COD. Average removal
efficiencies were( 79.8 %,45.4 %) for turbidity ,(78.2 % 61.3 %),for TSS,(47.9 %,52.1 %) for
COD ,(30.3 %,29.8 %) for NO3
-,
and (83.73%,77.6 %) for PO4
3
for planted and unplanted cells
respectively .Thus ,planted cell achieved the highest removal efficiency than unplanted cell.This
study concluded that vegetated horizontal subsurface flow constructed wetland (HSSF-CW) was
found to be more effective for removal of pollutants from coffee processing wastewater than non vegetated horizontal subsurface flow constructed wetland
