Equilibrium studies of cadmium biosorption by presumed non-viable bacterial strains isolated from polluted sites

Presumed non-viable high resistant Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia AL96Co, Corynebacterium kutscheri FL108Hg, and Rhodococcus sp AL03Ni were studied for Cd2+ adsorption potentials. Moderate temperature, acidic pH, and high ionic strength were required for bacterial-sorption of cadmium, attaining isothermic equilibrium within 20 min. Experimental cadmium-biosorption data fitted well into biosorption isotherms. The adsorption capacities of the bacterial cell masses spanned 0.003-0.009 l mg(-1) (Langmuir model) and 0.43-0.68 (Freundlich model), while binding capacity ranged from 1.14 to 56.16 mg gdw(-1), with maximum achievable cadmium uptake of 62.07-109.37 mg gdw(-1). The bacteria selectively removed the metal at low concentration (100.0 mg l(-1)) with an efficiency ranging from 50.0% to 80.0%, while approximately 80.0-92.0% removal efficiency was obtained at higher ionic concentrations (450.0 mg l(-1)). About 92.66% of the adsorbed metal was recovered from strain CA207Ni upon desorption, and approximately 91.7% of Cd2+ in solution was re-adsorbed onto the biomasses. In this work, effective feasible biosorption of Cd2+ in simulated wastewater system at harsh physico-chemistry, using non-viable resistant bacterial strains was demonstrated. The results indicate that the bacterial strains are sustainable tools for the detoxification of cadmium ions in industrial effluents via wastewater treatment, and cadmium demobilisation in contaminated ecosystem. Crown Copyright (C) 2014 Published by Elsevier Ltd. All rights reserved.