A new method for mercury removal

• Published in: Biotechnology letters 2005-11, Vol.27 (21), p.1649-1655
• Main Authors: ESSA, Ashraf M. M, MACASKIE, Lynne E, BROWN, Nigel L
• Format: Article
• Language: English
• Subjects: Aerobiosis - physiology; Biological and medical sciences; Biotechnology; Cell culture; Chemical Precipitation; Fundamental and applied biological sciences. Psychology; Gases; Heavy metals; Klebsiella pneumoniae; Klebsiella pneumoniae - growth & development; Mercury; Mercury - metabolism; Organosulfur compounds; Pneumonia; Water Pollutants - metabolism; Water Purification - methods
• ISSN: 0141-5492; 1573-6776
• DOI: 10.1007/s10529-005-2722-9

A method is described for the removal of mercury from solution by using the off-gas produced from aerobic cultures of Klebsiella pneumoniae M426. Cells growing in Hg-supplemented medium produced a black precipitate containing mercury and sulphur. The ratio of Hg:S was determined as approximately 1:1 by analysis using proton-induced X-ray emission, suggesting precipitation of HgS within the culture. The outlet gases produced by a mercury-unsupplemented aerated culture were bubbled into an external chamber supplemented with up to 10 mg HgCl(2)/ml. A yellowish-white precipitate formed, corresponding to 99% removal of the mercury from solution within 120 min. Energy dispersive X-ray microanalysis showed that this metal precipitate consisted of mercury, carbon and sulphur. Formation of mercury carbonate was discounted since similar precipitation occurred at pH 2 and no oxygen was detected in the solid, which gave an X-ray powder pattern suggesting an amorphous material, with no evidence of HgS. Precipitation of mercury with a volatile organosulphur compound is suggested. Bio-precipitation of heavy metals by using culture off-gas is a useful approach because it can be used with concentrated or physiologically incompatible solutions. Since the metal precipitate is kept separate from the bacterial biomass, it can be managed independently.