Details zur Publikation

Kategorie Textpublikation
Referenztyp Zeitschriften
DOI 10.1002/elsc.200520141
Titel (primär) Bioleaching of heavy metal polluted sediment: influence of temperature and oxygen (Part 1)
Autor Löser, C.; Zehnsdorf, A.; Görsch, K.; Seidel, H.
Quelle Engineering in Life Sciences
Erscheinungsjahr 2006
Department UBT; UBZ
Band/Volume 6
Heft 4
Seite von 355
Seite bis 363
Sprache englisch
Keywords Bioremediation; Heavy metals; Modeling; Temperature
Abstract A remediation process for heavy metal polluted sediment has previously been developed in which the heavy metals are removed from the sediment by solid-bed bioleaching using elemental sulfur (S0): the added S0 is oxidized by the indigenous microbes to sulfuric acid that dissolves the heavy metals which are finally extracted by percolating water. In this process, the temperature is a factor crucially affecting the rate of S0 oxidation and metal solubilization. Here, the effect of temperature on the kinetics of S0 oxidation has been studied: oxidized Weiße Elster River sediment (dredged near Leipzig, Germany) was mixed with 2 % S0, suspended in water and then leached at various temperatures. The higher the temperature was, the faster the S0 oxidized, and the more rapid the pH decreased. But temperatures above 35 °C slowed down S0 oxidation, and temperatures above 45 °C let the process – after a short period of acidification to pH 4.5 – stagnate. The latter may be explained by the presence of both neutrophilic to less acidophilic thermotolerant bacteria and acidophilic thermosensitive bacteria. Within 42 days, nearly complete S0 oxidation and maximum heavy metal solubilization only occurred at 30 to 45 °C. The measured pH(t) courses were used to model the rate of S0 oxidation depending on the temperature using an extended Arrhenius equation. Since molecular oxygen is another factor highly influencing the activity of S0-oxidizing bacteria, the effect of dissolved O2 (controlled by the O2 content in the gas supplied) on S0 oxidation was studied in suspension: the indigenous S0-oxidizing bacteria reacted quite tolerant to low O2 concentrations; the rate of S0 oxidation – measured as the specific O2 consumption – was not affected until the O2 content of the suspension was below 0.05 mg/L, i.e., the S0-oxidizing bacteria showed a high affinity to O2 with a half-saturation constant of about 0.01 mg/L. Stoichiometric coefficients describing the relationship between the mass of S0, O2 and CO2 consumed are scarcely available. The growth of S0-oxidizing, obligate aerobic, autotrophic bacteria was, therefore, stoichiometrically balanced (by using a yield coefficient of YX/S = 0.146 g cells/g S0, calculated with data from the literature): 24.14 S0 + 29.21 O2 + 27.14 H2O + 5 CO2 + NO3→ C5H7O2N + 24.14 SO42– + 47.28 H+, which resulted in Ymath image = 1.21 g O2/g S0 and Ymath image = 0.28 g CO2/g S0.
dauerhafte UFZ-Verlinkung
Löser, C., Zehnsdorf, A., Görsch, K., Seidel, H. (2006):
Bioleaching of heavy metal polluted sediment: influence of temperature and oxygen (Part 1)
Eng. Life Sci. 6 (4), 355 - 363 10.1002/elsc.200520141