In the current study, dried ground mixed waste of olive waste and water hyacinth was subjected to the treatment of wastewater contaminated with stable or radioactive cobalt and cesium. Contact time, temperature, amount of adsorbent, metal ion concentration and pH-value were evaluated as the most potent factors that affect the adsorption process. Concentrations of Co and Cs ions before and after treatment are measured using ICP-OES technique. Moreover, kinetic and equilibrium isotherm parameters were investigated by explaining the equilibrium data by induction of two isotherms, “Langmuir” and “Freundlich”. Experimental results indicated that more than 85% of 60Co and 134Cs were efficiently removed from spiked wastewater after one hour of contact time by using 0.2 g of dried mixed waste. The optimal time to remove Cs+ and Co2+ was 50 and 90 min, respectively. The kinetic study showed that the adsorption of Cs+ and Co2+ were better suited to the second order. The most favorable pH value was at a range of 6–7 for Cs+ and 5–6 for Co2+. R2 values were higher at the Freundlich isotherm, indicating that the adsorption process was taking place according to Freundlich isotherm at all temperatures for Co2+ and Cs+ ions.