Ethanol utilization by sulfate‐reducing bacteria: An experimental and modeling study

Abstract

A mixed culture of sulfate-reducing bacteria containing the species Desulfovibrio desulfuricans was used to study sulfate-reduction stoichiometry and kinetics using ethanol as the carbon source. Growth yield was lower, and kinetics were slower, for ethanol compared to lactate. Ethanol was converted into acetate and no significant carbon dioxide production was observed. A mathematical model for growth of sulfate-reducing bacteria on ethanol was developed, and simulations of the growth experiments on ethanol were carried out using the model. The pH variation due to sulfate reduction, and hydrogen sulfide production and removal by nitrogen sparging, were examined. The modeling study is distinct from earlier models for systems using sulfate-reducing bacteria in that it considers growth on ethanol, and analyzes pH variations due to the product-formation reactions.

Biotreatment of acidic zinc- and copper-containing wastewater using ethanol-fed sulfidogenic anaerobic baffled reactor

“…Total VFA and acetate concentrations were almost similar for all compartments. This may indicate that ethanol is converted to acetate, which may be further oxidized to CO 2 and H 2 O as previously reported in other studies [2,3,7,21]. The COD (Fig.…”

“…5) measurements showed that the remaining COD in the effluent of the reactor was due to acetate. Although serious acetate accumulation was not observed in the present study, acetate accumulation may take place at higher loadings as previously reported [2,3,7,[21][22][23]. Moreover, Sahinkaya et al [22] reported acetate oxidation is the limiting step in sulfate reducing bioprocesses.…”

“…The mining of sulfide ores or coal generates acid mine drainage (AMD) upon interaction of air and water with sulfides, mainly pyrite (FeS 2 ) [1][2][3]. The formation of acidic wastewaters can continue even tens or hundreds of years after mine closure if the conditions remain favorable [4,5].…”

“…In the presence of organic compounds, sulfate is microbially reduced to H 2 S under anaerobic conditions and heavy metals (especially, Cu, Pb, Zn, Cd, Ni, Fe) form stable precipitates with the produced H 2 S. Moreover, produced bicarbonate increases the pH of the wastewater. This way, metals and sulfate are concomitantly removed and pH can be increased to neutral values in a single reactor [2,3,7,8].…”

“…Sulfate reducing bacteria (SRB) utilize several low molecular weight substrates, such as lactate, formate, acetate, ethanol and hydrogen. Ethanol is a good substrate for SRB and suitable for large-scale applications [2,7]. Under sulfidogenic conditions, ethanol is first converted to acetate and in the second step acetate may further be oxidized to CO 2 .…”