Browsing by Subject "Biological sulfate reduction"

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    Effect of culture conditions on the competition between lactate oxidisers and fermenters in a biological sulfate reduction system
    (Elsevier, 2012) Oyekola, Oluwaseun O; Harrison, Susan T L; van Hille, Robert P
    Kinetic constants (μmax and Ks) describing the predominance of lactate oxidation and fermentation were determined in chemostat cultures. The kinetics of sulfate reduction and lactate utilization were determined from 0.5 to 5 d residence times at feed sulfate concentrations of 1.0–10.0 g l−1. The kinetics of lactate fermentation in the absence of sulfate were investigated at residence times of 0.5–5 d. The lactate oxidizers (LO) were characterized by a μmax of 0.2 h−1 and Ks value of 0.6 g l−1 compared with a μmax of 0.3 h−1 and Ks of 3.3 g l−1 for the lactate fermenters (LF). Using mathematical models, it was shown that LO competed more effectively for lactate at low lactate concentrations (⩽5 g l−1) and high sulfide concentrations (0.5 g l−1). Lactate fermenters outcompeted the oxidizers under conditions of excess lactate (>5 g l−1) and low sulfide (0.014–0.088 g l−1).
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    Effect of culture conditions on the competitive interaction between lactate oxidizers and fermenters in a biological sulfate reduction system
    (Elsevier, 2012) Oyekola, Oluwaseun O; Harrison, Susan T L; Van Hille, Robert P
    Kinetic constants (lmax and Ks) describing the predominance of lactate oxidation and fermentation were determined in chemostat cultures. The kinetics of sulfate reduction and lactate utilization were determined from 0.5 to 5 d residence times at feed sulfate concentrations of 1.0–10.0 g l1 . The kinetics of lactate fermentation in the absence of sulfate were investigated at residence times of 0.5–5 d. The lactate oxidizers (LO) were characterized by a lmax of 0.2 h1 and Ks value of 0.6 g l1 compared with a lmax of 0.3 h1 and Ks of 3.3 g l1 for the lactate fermenters (LF). Using mathematical models, it was shown that LO competed more effectively for lactate at low lactate concentrations (65gl1 ) and high sulfide concentrations (0.5 g l1 ). Lactate fermenters outcompeted the oxidizers under conditions of excess lactate (>5 g l1 ) and low sulfide (0.014–0.088 g l1 ). 2011 E
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    Study of anaerobic lactate metabolism under biosulphidogenic conditions
    (IWA Publishing, 2009) Oyekola, Oluwaseun A; van Hille, Robert P; Harrison, Susan T L
    Biological sulfate reduction (BSR) has been reported to have potential for the treatment of acid mine drainage (AMD). The provision of a suitable carbon source and electron donor for this process remains a challenge. Lactate offers potential advantages as carbon source and electron donor in the biological sulfate reduction process. As this substrate is utilized by both fermentative bacteria and oxidative sulfate-reducing bacteria (SRB), the effect of feed sulfate concentration on the lactate pathways utilized under biosulfidogenic conditions was investigated. Studies were carried out in chemostat bioreactors across a range of residence times, using an enriched culture of SRB. The stoichiometry of biological sulfate reduction was affected by feed sulfate concentration and dilution rate. Incomplete oxidation of lactate was dominant at low feed sulfate concentration (1.0 g/L), while the yield of propionate from lactate metabolism increased at feed sulfate concentrations of 2.5–10.0 g/L, indicating the occurrence of lactate fermentation. Furthermore, at each sulfate feed concentration, in the range 2.5–10.0 g/L, the ratio in which lactate was metabolized by the oxidative and fermentative pathways varied with varying dilution rates. Lactate oxidation was higher at a feed sulfate concentration of 10.0 g/L relative to 2.5 and 5.0 g/L. The volumetric lactate utilization rate was enhanced by increasing the feed sulfate concentration. However, the proportion of total lactate consumed that was channelled into providing electrons for other activities apart from sulfate reduction also increased over the range of increasing sulfate concentrations studied and appeared to be a function of residual lactate and sulfide concentrations.