Biogenic sulfide corrosion

  1. Articles needing additional references from June 2007
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  4. Sewerage
  5. Bacteria
  6. Cement
  7. Concrete
  8. Corrosion


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Biogenic Sulfide Corrosion is a bacterially mediated process of forming hydrogen sulfide gas and the subsequent conversion to sulfuric acid that attacks concrete and steel within wastewater environments. The hydrogen sulfide gas is oxidized in the presence of moisture to form sulfuric acid that attacks the matrix of concrete. The effect of sulfuric acid on concrete and steel surfaces exposed to severe wastewater environments can be devastating.[1]

Fresh domestic sewage entering a wastewater collection system contains an abundance of sulfates, SO42-. In the absence of dissolved oxygen and nitrates, these sulfates are reduced by sulfate reducing bacteria (SRB), identified primarily from the obligate anaerobic species Desulfovibrio, to form H2S via a complex pathway of biochemical reactions.

Once the H2S gas diffuses into the headspace environment above the wastewater, a sulfur oxidizing bacteria (SOB), primarily genus Thiobacillus aerobic bacteria, which colonize on pipe crowns, walls, and other surfaces above the waterline in wastewater pipes and structures, metabolize the H2S gas and oxidize it to H2SO4. This oxidizing process can take place where there is an adequate supply of hydrogen sulfide gas greater than 2 ppm, high relative humidity, and atmospheric oxygen.

See also

References

  1. ↑ O’Dea, Vaughn, “Understanding Biogenic Sulfide Corrosion,”MP (November 2007), pp. 36-39.

2. Pomeroy,RD, 1976, "The problem of hydrogen sulphide in sewers". Published by the Clay Pipes Development Association.

Note that this report contains errors in the equation: the pipeline slope (S, p. 8) is quoted as m/100m, but should be m/m. This introduces a factor of 10 under-estimate in the calculation of the 'Z factor', used to indicate if there is a risk of sullphide-induced corrosion, if the published units are used. The web link is to the revised 1992 edition, which contains the units error - the 1976 edition has the correct units.

3. D. Weismann, M. Lohse (Hrsg.): "Sulfid-Praxishandbuch der Abwassertechnik; Geruch, Gefahr, Korrosion verhindern und Kosten beherrschen!" 1. Auflage, VULKAN-Verlag, 2007, ISBN 978-3-8027-2845-7.


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