estimation of bioremediation potential of cyanobacteria for removal of heavy metals from aqueous solutions

Cyanobacteria have been poised as candidate for bioremediation of heavy metals contamination. samples were taken from effluent of fooladshahr stabilization pond wastewater treatment plant. cyanobacteria were identified by microscopic and molecular methods. most tolerant cyanobacteria against cadmium and lead toxicity were determined through acute toxicity experiment. selected cyanobacteria were subjected to absorption experiment in laboratory. influence of initial metal concentration, biomass quantity, temperature and ph on removal efficiency was assayed. also, comparison of hot plate digestion technique versus closed refluxed digestion method was undertaken. additionally, development of a method for detection limit improvement of graphite furnace atomic absorption spectrometry for determination of low concentrations of intracellular fraction of removed heavy metal was studied. microcystis aeruginosa and nostoc muscorum were identified as most insensitive organisms against lead and cadmium toxicity, indicating cd and pb ec50 values of 20 mg/l and 15 mg/l for former and 43 and 67 mg/l for later. m.aeruginosa showed maximum removal efficiency of cd2+ in temperature 28 c, biomass quantity of 0.2g and ph 7 as well as highest removal of pb in mentioned conditions of 25c, 0.1g and 6. optimum values of ph, temperature and biomass quantity for cd removal by nostoc muscorum were 6.5, 30 and 2gr/l and. pb removal peaked under conditions consisting of ph 5.5, temperature 35 c and biomass dosage 2g/l. closed reflux digestion method was found to be a good alternative for decomposition of cyanobacterial supernatant. introduction of a larger volume of sample through injection of sample for several time with intermediate drying and pyrolysis stages led to ability for measurement of very low concentrations of intracellular heavy metal.