Comparison of biooxidation with carbon dioxide assimilation during bacterial growth on ferrous ion or elemental sulfur

Abstract

Biomass and oxygen uptake activity profiles of a mixed bioleaching culture were studied and compared at various temperatures. Bacteria were grown on ferrous ion or elemental sulfur in a Micro-Oxymax respirometer apparatus that allowed measurement of both oxygen consumption and carbon dioxide assimilation. Balanced growth was observed between 10 degrees C and 35 degrees C, with an optimum at 30 degrees C, on both energy sources. No significant growth was observed at the lowest temperature used, 5 degrees C, or at the highest temperature used, 40 degrees C. The oxygen to carbon dioxide molar yield was 50:1 when growing on ferrous ion but only 17:1 when growing on elemental sulfur. Upon transfer from a sulfide ore to a new energy source, greater numbers in the inoculum reduced the duration of the lag phase. Lag phase duration was also reduced by proximity to the optimum growth temperature. A longer lag phase decreased the achievable growth rate of the cells exponentially, significantly affecting biooxidation activity.

Controls and Rates of Acid Production in Commercial‐Scale Sulfur Blocks

“…Because S 0 oxidation (Eq. [1]) is an exothermic reaction with a free energy of −415 kJ mol −1 oxidized S 0 (Lizama et al, 2002), the rate of heat generated in the S 0 block is directly proportional to the β O2 estimated from the [O 2 ] modeling. Rates of heat generation (G) were estimated by converting the modeled β O2 values to a S 0 oxidation rate (using reaction [1]) and multiplying by 415 kJ mol −1 S 0 The thermal modeling was used to verify if modeled β O2 values were reasonable and to assess the importance of S 0 oxidation in controlling temperatures within the block.…”

“…The fundamental control of S 0 oxidation to SO 4 (i.e., the production of H 2 SO 4 ) is the activity of heterotrophic and autotrophic microorganisms (Janzen and Bettany, 1987a). Elemental sulfur oxidation by heterotrophic and autotrophic microorganisms requires molecular O 2 as an electron acceptor (Fenchel et al, 1998) according to the following reaction (Lizama et al, 2002): Autotrophs (e.g., Acidithiobacilli ) use the energy transferred during S 0 oxidation for growth and the fixation of C‐1 compounds, such as CO 2 (Lizama et al, 2002). Elemental sulfur oxidation during heterotrophic activity is mainly incidental (Baldensperger, 1976) because organic material is oxidized for energy and growth, with CO 2 being produced.…”

“…Partially saturated conditions facilitate optimal reaction rates as water is available for Reaction [1], yet the ingress of O 2 is not limited (Attoe and Olson, 1966; Janzen and Bettany, 1987b). Temperature increases S 0 oxidation rates according to the Arrhenius equation, with oxidation rates being limited below 5°C (Janzen and Bettany, 1987b; Lizama et al, 2002).…”

“…Th e fundamental control of S 0 oxidation to SO 4 (i.e., the production of H 2 SO 4 ) is the activity of heterotrophic and autotrophic microorganisms (Janzen and Bettany, 1987a). Elemental sulfur oxidation by heterotrophic and autotrophic microorganisms requires molecular O 2 as an electron acceptor (Fenchel et al, 1998) according to the following reaction (Lizama et al, 2002): 2S 0 + 3O 2 + 2H 2 O→2H 2 SO 4 [1]…”

Isolation and identification of the thermophilic alkaline desulphuricant strain

“…As a new desulfurization method, the microorganism desulfurization way drew more attention in various countries [10][11][12][13][14][15][16][17][18] , because it had appeared to have lower cost, higher yield of second-produces, and higher desulfurization efficiency. However, it had some shortages, such as longer desulfurization time, higher possibilities of aberrance in desulfurization processes, and more complicated desulfurization mechanism in desulfurization processes.…”