Duckweed plants usually are able to grow on water rich in organic nutrients which supply thesernplants with the necessary growth requirements. Their rapid growth in nutrient rich wastewaterrnand worldwide distribution makes these plants suitable for wastewater treatment.rnWastewater effluent collected from Arat Kilo campus of Addis Ababa University was used tornevaluate duckweed plantsâ€™ treatment efficiency. The system was designed using two differentrnphases. Phase I was with operating conditions of Hydraulic Residence Time (HRT) of 10 days,rnFlow Rate (Q) of 0.0081m3/d and Hydraulic Loading Rate (HLR) of 0.03m/d. Phase II wasrndesigned with operating conditions 43 Kg/ha/d of OLR, 15 days of HRT, 0.0064m3/d of FlowrnRate and 0.024m/d of HLR. A total of 18 samples for the entire treatment period were collectedrnand analyzed for the selected physico-chemical and bacteriological parameters. For algalrnbiomass determination samples were collected every five days for each treatment phase andrnanalyzed. A total of seven plant biomass samples were evaluated for crude protein content.rnRemoval efficiency of the duckweed plant obtained for some of wastewater quality parametersrnwere 89% (BOD5), 87% (COD), 87% (TSS), 72.5% (NO3rn-), 44% (NH4rn+), 57.5% (TN), 94.4%rn(PO4rn3-) , 69.8% (TP), 17.1%,(SO4rn2-), 83.6% (S2-), 99.9% (TC), 99.7% (FC) for Phase I andrn89.5% (BOD5), 80.6% (COD), 95% (TSS), 85.3% (NO3rn-), 47.4% (NH4rn+), 51.8% (TN), 94.3%rn(PO4rn3-), 71.4% (TP), 27.5% (SO4rn2-), 86.6% (S2-), 99.9% (TC), 99.9% (FC) for Phase II.rnANOVA analysis results have shown that there was statistically significant difference betweenrnduckweed covered treatment cell and control except for bacterial indicators, Total Phosphorusrnand Sulfate. Paired t-test results have showed statistically significant (p