Document Type : Original Article

Authors

• Vahid Reza Fanaie ¹
• Mohsen Karrabi ¹
• Mohammad Mehdi Amin ²
• Bahar Shahnavaz ³
• Ali Fatehizadeh ⁴

¹ Department of Civil Engineering, Faculty of Engineering, Ferdowsi University of Mashhad, Mashhad, Iran

² Environment Research Center, Research Institute for Primordial Prevention of Non-communicable Disease, Isfahan University of Medical Sciences, Isfahan; Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran

³ Department of Biology, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, Iran

⁴ Department of Environmental Health Engineering, School of Health, Isfahan University of Medical Sciences, Isfahan; Student Research Center, Isfahan University of Medical Sciences, Isfahan, Iran

Abstract

Aims: In this study, the adsorption capacity of dried anaerobic digested sludge (DADS) and dried activated sludge (DAS) for the removal of 4-chlorophenol (4-CP) from aqueous solutions was evaluated. Materials and Methods: Both anaerobic digested sludge and activated sludge were collected from a south municipal wastewater treatment plant in Isfahan. Batch biosorption experiments were carried out to investigate the effects of solution pH, contact time, biosorbent dosage and initial concentration of 4-CP. The residual concentration of 4-CP was analyzed by colorimetry method. Isotherms and kinetic equations were applied to study kinetic and equilibrium of adsorption. Results: Results indicated that, DAS have higher removal potential in comparison with DADS. The optimum pH was detected to be 3 for DADS and 4 for DAS. By increasing contact time and biosorbent dosage, removal efficiency of 4-CP increased for both biosorbents. Furthermore, a decreasing trend was observed when initial concentrations were increased. The equilibrium time for DAS was 2.5 h and for DADS was 4 h. The maximum adsorption capacity were found 1.67 mg/g for DAS and 0.93 mg/g for DADS. The 4-CP removal equilibrium isotherm was modeled by Freundlich equation. Kinetic studies suggested that pseudo-first-order model for DADS and second order for DAS were the best choices to describe biosorption behavior. Conclusion: According to the present study, DAS, have better efficiency for the removal of 4-CP in comparisons with DADS.

Keywords

• 4-chlorophenol
• activated sludge
• biosorption
• digested sludge