Prediction of Sulfide Build‐up in Filled Sanitary Sewers

Laboratory experiments using a synthetic sewage flowing through a model sewer have been carried out so as to investigate the effect of sulfate concentration on the rate of production of sulfide. The results have been interpreted and analyzed taking into account mass‐transfer resistances. The analysis provides a rational explanation as to why in some situations Pomeroy's predictive equation may be adequate, while in other situations Thistlethwayte's equation may suffice. However, neither equation properly accounts for the effects caused by mass‐transfer resistances in the slime and liquid phases. Improvements to the present predictive procedures require assessment and allowance for these mass‐transfer resistances together with further data on the intrinsic rate of conversion of sulfate to sulfide within the slime phase. The experiments indicated that the removal rate was zero‐order with respect to sulfate and the value of the rate constant was in the range $5-8\mathrm{mg}{\mathrm{cm}}^{-3}{h}^{-1}$ at 20 °C. Areas in which further data are required are noted in the conclusions of the paper.