## Abstract

All detrimental phenomena (malodors, metal corrosion, concrete disintegration, health hazard) associated with hydrogen sulfide in gravity sewers depend on the rate of H_{2}S emission from the aqueous phase to the gas phase of the pipe. In this paper a different approach for predicting H_{2}S_{(g)} emission rates from gravity sewers is presented, using concepts adapted from mixing theory. The mean velocity gradient (G=γSV/μ; S is the slope, V the mean velocity), representing mixing conditions in gravity flow, was used to quantify the rate of H_{2}S _{(g)} emission in part-full gravity sewers. Based on this approach an emission equation was developed. The equation was verified and calibrated by performing 20 experiments in a 27-m gravity-flow experimental-sewer (D=0.16m) at various hydraulic conditions. Results indicate a clear dependency of the sulfide stripping-rate on G1 (R2=0.94) with the following overall emission equation:-d[ST]dt=8×10-7γSV/μwAcs1.024(T-20)(ST1+Ks110- pH+Ks1Ks210-2pH-PpH2SKH), where S_{T} is the total sulfide concentration in the aqueous phase, mg/L; w the flow surface width, m; A_{cs} the cross-sectional area, m^{2}; T the temperature,°C; K_{H} the Henry's constant, mol L^{-1} atm^{-1}; and P_{pH2S} the partial pressure of H_{2}S_{(g)} in the sewer atmosphere, atm.

Original language | English |
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Pages (from-to) | 259-266 |

Number of pages | 8 |

Journal | Water Research |

Volume | 40 |

Issue number | 2 |

DOIs | |

State | Published - Jan 2006 |

Externally published | Yes |

## Keywords

- Gas transfer
- Gravity sewers
- HS emission
- Mean velocity gradient