Corrosion of concrete sewers is associated with the biological oxidation of hydrogen sulfide to sulfuric acid by bacteria of the genus Thiobacillus. Inhibition of acid production by these organisms, was investigated by challenging established cultures with a heterotrophic competitor under controlled conditions. Two-organism competition experiments (T. thiooxidans or T. neapolitanus versus the heterotrophic competitor) were conducted in a bench-scale, continuous-flow, constantly stirred tank reactor. Results were sensitive to the influent nitrogen:carbon ratio. Under conditions designed to produce nitrogen-limited growth, the numbers of thiobacilli were reduced 60- to 1 200-fold after introduction of the competitor. Effluent sulfate concentrations, an indicator of acid production, dropped by 85%. Under carbon-limited conditions, modest reductions in thiobacilli cell density and effluent sulfate concentration were observed. Microbial competition reduced acid production under the conditions of the experiment. The results suggest that strategies based on competitive displacement of thiobacilli to inhibit corrosion of concrete sewers may be feasible.
ASJC Scopus subject areas
- Environmental Chemistry
- Ecological Modeling
- Water Science and Technology
- Waste Management and Disposal