Biosorption of Pb(II) by using digested sludge obtained from a municipal wastewater treatment plant in Tehran was examined. The aims of this investigation were biosorption of Pb(II) ions onto chemically treated digested sludge with hydrogen peroxide (H₂O₂) solution and determination of kinetic and isotherm of biosorption. Biosorption capacity of two types of sludge (treated and untreated) for biosorption of Pb(II) ions was investigated as function of initial Pb(II) concentration and pH using batch biosorption systems. The equilibrium biosorption capacity increased with increasing of initial metal ion concentrations and pH for both of digested sludge. The pseudo-second order kinetic model was found to be slightly suitable than the pseudo-first order kinetic model to correlate the experimental data for two types of digested sludge (R²>0.9). Regarding the applicability of the isotherm models, the freundlich model was found to be suitable than the other isotherm models. According to obtained q(max) from Langmuir isotherm, biosorption of Pb(II) by H₂O₂ treated digested sludge was found to perform better than untreated digested sludge. The maximum biosorption capacity was given 185.19 and 144.93 mgg⁻¹ for H₂O₂ treated and untreated digested sludge, respectively. Also, the constant of energy (B) between the Pb(II) ions and the adsorbent surface, calculated using BET isotherm model, obtained 5401 and 3401 for H₂O₂ treated and untreated digested sludge, respectively. These results indicate the usefulness of H₂O₂ treated digested sludge as a biosorbent for Pb(II) biosorption.
Problem statement: Heavy metals have been one of hazardous components in industrial effluents that can be damaged on the environment by discharging uncontrolled wastewater. The aims of this investigation were biosorption of Cd (II) ions onto pretreated dried activated sludge and determination of kinetic and isotherm of biosorption. Approach: Activated sludge was obtained from Tehran municipal wastewater treatment plant. Activated Sludge was dried and used for biosorbtion of Cd (II) ions from aqueous solution. Dried Activated Sluge (DAS) was pretreated with three different solutions (H 2 O 2 , NaOH and ethanol). Biosorption capacity of different types of DAS to remove Cd (II) ions was investigated as a function of Cd (II) concentrations at variable initial Cd (II) concentrations between 10 and 500 mg L −1 with a DAS particle size 0.2-0.3 mm using batch biosorption experiments.Results: Biosorption of Cd (II) by Dried Activated Sludge (DAS) was found to perform better than the others after pretreatment with H 2 O 2 . The maximum biosorption capacity was given 256.41, 217.39, 212.77 and 204.08 mg g −1 for the H 2 O 2 , NaOH; Ethanol pretreated and untreated DAS, respectively. The pseudo-second order kinetic model was found to be more suitable than the pseudo-first order kinetic model to correlate the experimental data for all types of DAS (R 2 >0.9). The Freundlich isotherm was found to fit the experimental data slightly better than the Langmuir isotherm model for all pretreated and untreated DAS (R 2 >0.99). Conclusion: It can be concluded that pretreatment DAS yield higher Cd (II) biosorption capacity, especially DAS that pretreated with H 2 O 2 .
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