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Impact of fluctuations in gaseous H2S concentrations on sulfide uptake by sewer concrete: The effect of high H2S loads

Journal Article


Abstract


  • The acid production from the oxidation of hydrogen sulfide (H2S) in sewer air results in serious corrosion

    of exposed concrete surfaces in sewers. Large fluctuations of gaseous H2S concentrations occur in sewers

    due to the diurnal profiles of sewage flow and retention times and the necessity of intermittent pumping

    of sewage from pressure pipes into gravity pipes. How the high concentrations of H2S due to these events

    may affect H2S uptake and subsequent corrosion by concrete sewers is largely unknown. This study

    determined the effect of short- and long-term increases in H2S levels on the sulfide uptake rate (SUR) of

    concrete surfaces with an active corrosion layer. The results showed that during the high load situation

    the SUR increased significantly but then decreased (compared to the baseline SUR) by about 7e14% and

    41e50% immediately after short- and long-term H2S high-load periods, respectively. For both exposure

    conditions, the SUR gradually (over several hours) recovered to approximately 90% of the baseline SUR.

    Further tests suggest multiple factors may contribute to the observed decrease of SUR directly after the

    high H2S load. This includes the temporary storage of elemental sulfur in the corrosion layer and inhi-

    bition of sulfide oxidizing bacteria (SOB) due to high H2S level and temporary acid surge. Additionally,

    the delay of the corrosion layer to fully recover the SUR after the high H2S load suggests that there is a

    longer-term inhibitive effect of the high H2S levels on the activity of the SOB in the corrosion layer. Due to

    the observed activity reductions, concrete exposed to occasional short-term high H2S load periods had an

    overall lower H2S uptake compared to concrete exposed to constant H2S levels at the same average

    concentration. To accurately predict H2S uptake by sewer concrete and hence the likely maximum

    corrosion rates, a correction factor should be adopted for the H2S fluctuations when average H2S levels

    are used in the prediction.

Authors


  •   Sun, Xiaoyan (external author)
  •   Jiang, Guangming
  •   Bond, Philip (external author)
  •   Keller, Jurg (external author)

Publication Date


  • 2015

Citation


  • Sun, X., Jiang, G., Bond, P. L. & Keller, J. (2015). Impact of fluctuations in gaseous H2S concentrations on sulfide uptake by sewer concrete: The effect of high H2S loads. Water Research, 81 84-91.

Scopus Eid


  • 2-s2.0-84929383117

Number Of Pages


  • 7

Start Page


  • 84

End Page


  • 91

Volume


  • 81

Place Of Publication


  • United Kingdom

Abstract


  • The acid production from the oxidation of hydrogen sulfide (H2S) in sewer air results in serious corrosion

    of exposed concrete surfaces in sewers. Large fluctuations of gaseous H2S concentrations occur in sewers

    due to the diurnal profiles of sewage flow and retention times and the necessity of intermittent pumping

    of sewage from pressure pipes into gravity pipes. How the high concentrations of H2S due to these events

    may affect H2S uptake and subsequent corrosion by concrete sewers is largely unknown. This study

    determined the effect of short- and long-term increases in H2S levels on the sulfide uptake rate (SUR) of

    concrete surfaces with an active corrosion layer. The results showed that during the high load situation

    the SUR increased significantly but then decreased (compared to the baseline SUR) by about 7e14% and

    41e50% immediately after short- and long-term H2S high-load periods, respectively. For both exposure

    conditions, the SUR gradually (over several hours) recovered to approximately 90% of the baseline SUR.

    Further tests suggest multiple factors may contribute to the observed decrease of SUR directly after the

    high H2S load. This includes the temporary storage of elemental sulfur in the corrosion layer and inhi-

    bition of sulfide oxidizing bacteria (SOB) due to high H2S level and temporary acid surge. Additionally,

    the delay of the corrosion layer to fully recover the SUR after the high H2S load suggests that there is a

    longer-term inhibitive effect of the high H2S levels on the activity of the SOB in the corrosion layer. Due to

    the observed activity reductions, concrete exposed to occasional short-term high H2S load periods had an

    overall lower H2S uptake compared to concrete exposed to constant H2S levels at the same average

    concentration. To accurately predict H2S uptake by sewer concrete and hence the likely maximum

    corrosion rates, a correction factor should be adopted for the H2S fluctuations when average H2S levels

    are used in the prediction.

Authors


  •   Sun, Xiaoyan (external author)
  •   Jiang, Guangming
  •   Bond, Philip (external author)
  •   Keller, Jurg (external author)

Publication Date


  • 2015

Citation


  • Sun, X., Jiang, G., Bond, P. L. & Keller, J. (2015). Impact of fluctuations in gaseous H2S concentrations on sulfide uptake by sewer concrete: The effect of high H2S loads. Water Research, 81 84-91.

Scopus Eid


  • 2-s2.0-84929383117

Number Of Pages


  • 7

Start Page


  • 84

End Page


  • 91

Volume


  • 81

Place Of Publication


  • United Kingdom