Study the effects of various culture media compositions, iron bioreduction and heavy metal biosorption by the bacterium indigenous to the northwest of Iran Tabrizicola aquatica

Abstract

Introduction: The use of biological materials for effective removal and recovery of heavy metals from contaminated wastewaters has emerged as a potential alternative method to conventional treatment techniques. Discharge of heavy metals from various industries such as mining, ore processing, smelting and metal plating can easily create metal pollution and causes hazardous effects on humans, animals and environmental balances. Lead and cobalt and nickel are among those metals widely used in industry and their accumulation in the living tissues may cause serious health problems Aim: The aim of this paper was the laboratory study of bioreduction and biosorption of toxic metals (Ni2+, Co2+and Pb2+) from aqueous solution by the application of indigenous microorganisms and to Evaluate the recovery effects of Tabrizicola aquatica on bioremediation study and to determine minimal conditions for bacterial gowth. Methods: The optimum conditions of biosorption were determined by investigating the initial pH, contact time and the initial concentrations of metal ions at constant temperature (25 ◦C). A set of 100ml Erlenmeyer flasks containing 20 ml of the tested metal solutions were used in the batch experiments. The different concentrations of dried powdered dead cells (0.25–10 g/l) were exposed to various initial metal concentrations (10–300mg/l) for 15–120 min at 25◦C on a shaker at 120 rpm. After the incubation, the dried powdered dead cells were centrifugated at10,000 rpm for 10min. Supernatant and pellet were separately used to estimate for residual metal concentration by using atomic absorption spectroscopy. Results: The metal loading capacity of bacterial biomass was determined considering the effect of initial pH, contact time and initial metal ions concentration. The biosorption data were analyzed by Freundlich and Langmuir isotherm models. The maximum biosorption capacities, As (mg/l) were (Ni2+: 31.34±2.1, Co2+: 16.6±1.2, Pb2+: 22.12±2.3) and also Kb (1/mg): (0.041 Ni, 0.046 Co, 0.021 Pb) Kinetics rate of biosorption was also tested and it had been concluded that biosoption process follows the Pseudo-second order kinetic model .according to higher correlation coefficients which was obtained. Qexp: (6.19 Ni, 12.61 Co, 11.8 Pb). K2 : (0.0056 Ni, 0.0638 Co , 0.0291 Pb)