en Biology & physiology Biology & physiology پژوهشي Orginal research papers Capability of cyanobacterium, <em>Microcystis aeruginosa</em>, in the removal of cadmium and lead ions was investigated which was obtained after isolation from wastewater stabilization pond effluents. Influence of operational parameters including metal concentrations, pH, temperature and biomass dosage on removal efficiency was investigated. Also, applicability of closed reflux techniques for the digestion of cyanobacterial pellet was studied. A multi-phase washing method was developed in order to attain more elevated desorption efficiency. 1-5 washing cycles were repeated consecutively by the addition of new EDTA solution (4mM), stirring on mixer and centrifugation for each cycle. Maximum removal efficiency occurred at pH 7, temperature 28&deg;C and biomass dosage of 0.2g for Cd²⁺ and corresponding values of 6, 25&deg;C and 0.1g for Pb²⁺. In all tested concentrations of Cd²⁺ and Pb²⁺, extracellular absorption overweighed intracellular uptake with highest ratio of the former to the latter of 172 for Cd²⁺and 143 for Pb²⁺. EC₅₀ values attained for Cd²⁺and Pb²⁺were 20 mg L^-1 and 15 mg L^-1, respectively. The closed-reflux digestion method was found as a suitable choice for cyanobacterial pellet digestion. Three-stage consecutive washing procedure devised in our study gave desorption efficiencies of 92 and 86 percent for Cd²⁺ and Pb²⁺ respectively as compared with values of 52 and 44 percent for Cd²⁺ and Pb²⁺, respectively obtained by the conventional washing procedure. This investigation verifies the possibility of employing <em>M. aeruginosa</em> for removal of Cd²⁺ and Pb²⁺ from aqueous and wastewater solutions. <span dir="RTL"></span> Bioremediation, Cadmium, Lead, Microcystis aeruginosa 1994 2009 http://jifro.ir/browse.php?a_code=A-10-2800-1&slc_lang=en&sid=1 J. Cheraghpour cheraghpourjavad@gmail.com 100319475328460035716 100319475328460035716 No Science and Research University of Fars Z. Etemadifar z.etemadifar@sci.ui.ac.ir 100319475328460035717 100319475328460035717 Yes University of Isfahan S. Afsharzadeh s.afshar@biol.ui.ac.ir 100319475328460035718 100319475328460035718 No University of Isfahan N. Bahador nimabahador22@gmail.com 100319475328460035719 100319475328460035719 No Science and Research University of Fars