The ability of cassava waste biomass (untreated and acid treated) to remove heavy metals (Cu(II) and Zn(II) ) from single-ion solution and wastewater was investigated. All experiments were conducted using 10mM solutions of mixed metal ions of CuSO 4 .5H 2 O and ZnCl 2 . The uptake capacities of the two metal ions tested on the untreated and acid treated cassava waste biomass were 71.3 and 85.2 mg/g for Cu(II), and 43.4 and 58.1 mg/g for Zn(II) in single-ion solution. For wastewater, the uptake capacities of untreated and acid treated biomass was found to be 40.1 and 59.7 mg/g for Cu(II), and 38.6 and 38.7 mg/g for Zn(II), respectively. Metal ion uptake capacities in wastewater were lower than in single-ion solution probably due to competition of metal ions of different sizes on available binding sites. Uptake capacities of these metal ions on the biomass surface increased with acid treatment. Equilibrium sorption studies showed that the extent of metal uptake was enhanced by chemically modifying the cassava waste biomass by thiolation. Cassava waste biomass saturated with metal ions shows remarkable ability for metal recovery by dilute acid treatment, and can be used repeatedly for removal of heavy metals in single-ion solution and in wastewater effluents.