A master thesis from Aalborg University
Svovlbrinte Oxidation og Kloak Korrosion: Med artiklerne: Beskrivelse af svovlbrinte forårsaget korrosion af kloaksystemer – en ny tilgang. Svovlbrinte optagelses rater and biomasse koncentrationer af mikroorganismer fra korroderet beton.
[Hydrogen Sulfide Oxidation and Sewer Corrosion: Including the articles: Description of the hydrogen sulfide induced corrosion of concrete sewer systems - a new approach. Hydrogen sulfide uptake rates and biomass concentrations of microorganisms from corroded concrete.]
Author(s)
Term
10. term
Publication year
2009
Submitted on
2009-06-18
Pages
40 pages
Abstract
Hydrogen sulfide is removed from the sewer gas phase by absorption and oxidized on the exposed concrete surface, which results in concrete corrosion. The relation between actual and potential corrosion was investigated and described as a corrosion reduction factor. A study on the fate of partly oxidized hydrogen sulfide that is immobilized in corroded concrete was performed. This determined that the sulfur compounds immobilized in the corroded matrix has a significant corrosive potential. The immobilized sulfur compounds were oxidized to sulfuric acid and corroded the sewer, when a lack of hydrogen sulfide occurred. Furthermore, an investigation of the influence of atmosphere velocity on hydrogen sulfide removal rate in sewer systems was performed. This investigation indicated a significant increase in hydrogen sulfide removal with increasing sewer atmosphere velocities. Hydrogen sulfide oxidation in sewer systems was investigated in a bench scale bioreactor, with corroded concrete in suspension. The hydrogen sulfide concentration and the oxygen concentration were measured continuously during the run of the bioreactor. Samples for protein analysis were taken throughout the experiments. The results of these experiments indicate a variation in activity between different hydrogen sulfide oxidizing microorganisms. As an attempt to achieve a monoculture of the most active hydrogen sulfide oxidizing microorganisms, the reactor experiment was started by inoculating from a running reactor. This resulted in a better relation between hydrogen sulfide removal rates and protein concentration, as the bacterial diversity approached a culture of Acidithiobacillus. As a sub study, the kinetics of methyl mercaptane oxidation in sewer systems was investigated in the same bioreactor. The results of the methyl mercaptane oxidation showed that the diversity of microorganisms in corroded concrete enabled oxidation of methyl mercaptane. Furthermore, the results indicate that the culture of Acidithiobacillus that were achieved by inoculation, were unable to oxidize methyl mercaptane.
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