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Removing heavy metals by microorganisms

Now a days. the contamination by heavy metals has become one of the most important environmental problems. Among heavy metal ions. lead can be very harmful to human health and ecosystem. It has been known that lead can be accumulated inside microorganisms very easily. In other words. lead enters human body through food. water and air and then it is accumulated inside the bones instead of calcium. causing hemoglobiolnysis to happen. Biological absorption is a suitable method of removing accumulated lead from environment. The yeast. saccharomyesc is a suitable microorganism to remove it. 4 strain of Saccahromyces were isolated from industrial waste water saples. In order to study the amount of absorption qualitatively and the best strain in terms of metallic absorptivity was selected. After that. some effective factors in relation to biological absorption such as the initial concentration of metal . pH and et.al.. were considered. The maximum amount of absorption was determined in the following conditions duration of contact time. 2 hours. initial concentration; 500 ppm. pH; 4.5 . 65.1 mg g-1 dw. Also. entrapment method was used to immobilize the yeast cells and then the results showed that the adsorption rate of Pb (II) by the immobilized cells was higher than to their counterparts, free cells.