Journal of Hazardous Materials B120 (2005) 193–200 Study of Cu(II) biosorption by dried activated sludge: effect of physico-chemical environment and kinetics study Osman Gulnaz a, ∗ , Saadet Saygideger a , Erdal Kusvuran b a Department of Biology, Faculty of Arts and Sciences, Cukurova University, 01330 Balcalı, Adana, Turkey b Department of Chemistry, Faculty of Arts and Sciences, Cukurova University, 01330 Balcalı, Adana, Turkey Received 5 November 2004; received in revised form 5 January 2005; accepted 6 January 2005 Abstract Biosorption is a recent technology used to remove heavy metal ions from aqueous solutions. The biosorption of copper ions from aqueous solution by dried activated sludge was investigated in batch systems. Effect of solution pH, initial metal concentration and particle size range were determined. The suitable pH and temperature for studied conditions were determined as 4.0 and 20 ◦ C, respectively. The theoretical max biosorption capacity of activated sludge was 294 mg g -1 at 20 ◦ C for <0.063 mm particle size. The equilibrium data fitted very well to both Langmuir and Freundlich isotherm models. The pseudo first and second-order kinetic models were used to describe the kinetic data. The experimental data fitted to second-order kinetic model. The particle size and initial metal concentration were effected the biosorption capacity of dried activated sludge. An increase in the initial metal concentration increases of biosorption capacity, which also increases with decreasing particle size. Dried activated sludge has different functional groups according to the FT-IR results. © 2005 Elsevier B.V. All rights reserved. Keywords: Biosorption; Activated sludge; Copper; Biosorption kinetic; Heavy metal 1. Introduction Toxic heavy metal containing industrial wastewater can cause serious environmental pollution problems for aquatic life. The removal of toxic contaminants and organic pollu- tants from industrial wastewaters is one of the most important environmental issues. The main industrial sources of toxic metal contamination in wastewaters include electroplating, metal finishing, metallurgical, tannery, chemical manufactur- ing, mining and battery manufacturing industries, etc. Some heavy metals are necessary in small amounts for normal de- velopment of biological cycles; however most of these heavy metals are becoming toxic at high concentrations [1]. Many physico-chemical methods have been developed for heavy metal removal from aqueous solution, including ∗ Corresponding author. Tel.: +90 322 338 60 81; fax: +90 322 338 60 70. E-mail address: ogulnaz@cu.edu.tr (O. Gulnaz). chemical coagulation, evaporation, adsorption, extraction, ion-exchange and membrane separation process [2,3]. Among these methods, ion-exchange is a highly popular one and has been widely practiced in industrial wastewater treatment process. But the application of such processes is often restricted because they cannot guarantee the metal concentration limits required by regulatory standards as they produce wastes difficult to treat, either they can cause very expensive costs, especially when metal concentrations in the effluents are below 100 mg L -1 [4,5]. Adsorption is a well-established technique for heavy metal removal. Activated carbon is a widely used adsorbent material. In fact use of activated carbon can be expensive due to the regeneration required and loses in the application processes. Many investigators have studied inexpensive alternative materials instead of activated carbon for removal of heavy metal from wastewaters. Some of the these alternative adsorbent materials are algae [6], almond husk [7], clays [8], yeast biomass [9], perlite [10], maple sawdust 0304-3894/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jhazmat.2005.01.003