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Sulfide oxidation under chemolithoautotrophic denitrifying conditions
Ricardo Beristain Cardoso1, Reyes Sierra-Alvarez, Pieter Rowlette
1Department of Chemical and Environmental Engineering, University of Arizona, Tucson, Arizona 85721-0011, USA.
Biotechnology and Bioengineering
|June 30, 2006
Summary
Chemolithoautotrophic denitrifiers remove hydrogen sulfide by oxidizing sulfur compounds using nitrate. Controlling the sulfide/nitrate ratio dictates whether sulfide becomes elemental sulfur or sulfate.
Area of Science:
- Environmental microbiology
- Biogeochemical cycles
- Wastewater treatment
Background:
- Chemolithoautotrophic denitrifiers use inorganic sulfur compounds and nitrate for energy.
- These microbes are crucial for removing nitrogen and sulfur pollutants from various environmental streams.
Purpose of the Study:
- To investigate the physiology and kinetics of chemolithotrophic denitrification.
- To understand the role of electron donors (sulfide, elemental sulfur, thiosulfate) and nitrate availability.
- To assess the impact of sulfide concentration and acetate addition on denitrification.
Main Methods:
- Enrichment culture of chemolithotrophic denitrifiers.
- Controlled experiments varying electron donor and acceptor concentrations.
- Kinetic analysis of oxidation rates and inhibition effects.
Main Results:
- Complete sulfide oxidation to sulfate occurred with sufficient nitrate.
- Partial oxidation to elemental sulfur was observed under nitrate-limiting conditions.
- High sulfide concentrations (10.0 mM) significantly inhibited sulfoxidation rates.
- Low acetate levels (0.5 mM) enhanced denitrification and sulfate production.
Conclusions:
- Chemolithoautotrophic denitrification is effective for hydrogen sulfide removal.
- The sulfide/nitrate ratio is a key factor controlling the oxidation pathway (elemental sulfur vs. sulfate).
- Acetate can serve as a supplementary carbon source, enhancing the process.
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