Sorption of mercury, cadmium and lead by microalgae

Abstract

Forty-six strains of microalgae from BIOTECH Culture Collection (NSTDA), Microbiological Resources Center (TISTR) and Institute of Research and Food Development, 3 strains collected from Thai natural and industrial areas and 3 strains from the Gottingen University culture collection were tested for Mercury (Hg), Cadmium (Cd) and Lead (Pb) removal in aqueous solutions. In green algae, the highest Hg removal was by Scenedesmus sp., Chlorococcum sp., Chlorella vulgaris var. vulgaris and Fischerella sp., (97%, 96%, 94% and 92%, respectively). In blue green algae, highest Hg removal was by Lyngbya spiralis, Tolypothirx tenuis, Stigonema sp., Phormidium molle (96%, 94%, 94% and 93%, respectively). For Cd removal in green algae, the highest was by Chlorococcum sp., T5, Fischerella sp., Chlorella vulgaris var. vulgaris and Scenedesmus acutus (94%, 94%, 91%, 89% and 88%, respectively). In blue green algae, highest Cd removal was by Lyngbya heironymusii, Gloeocapsa sp., Phormidium molle, Oscillatoria jasorvensis and Nostoc sp. (97%, 96%, 95%, 94% and 94%, respectively). In green algae, highest Pb removal was by Scenedesmus acutus, Chlorella vulgaris var. vulgaris, Chlorella vulgaris, Scenedesmus vacuolatus and Chlorella vulgaris, (89%, 88%, 85%, 85% and 84%, respectively). In blue green algae, highest Pb removal was by Nostoc punciforme, Oscillatoria agardhii, Gloeocapsa sp., Nostoc piscinale, Nostoc commune and Nostoc paludosum (98%, 96%, 96%, 94%, 94% and 92%, respectively). Scenedesmus acutus had the highest concentration factor (CF) at 3,412, 4,591 and 4,078 for Hg, Cd and Pb, respectively. Tolypothrix tenuis had the highest maximum adsorption capacity of 27 mg Hg/g dry wt. at a minimum concentration of 1.04 mg/l, Scenedesmus acutus had the highest maximum adsorption capacity of 110 mg Cd/g dry wt. at a minimum concentration of 48 mg/l and Chlorella vulgaris had the highest maximum adsorption capacity of 127 mg Pb/g dry wt. at a minimum concentration of 130 mg/l.