Case study of hydrogen sulfide release in the sulfate-rich sewage drop structure

H₂S is one of the principal odor gases released from sewer networks and understanding the rate of H₂S release into sewer air space and ventilation to the atmosphere is crucial for preventing or minimizing odor and corrosion issues in sewer systems. TOXCHEM model was used to simulate the fate of H₂S gas in roads for this study. The model was calibrated for the spring and summer seasons and validated for the remainder of the seasons. The predicted behavior showed good correlation to measurements on real samples following statistical analysis, with R², R, and RMSE results between (0.93–0.97), (0.8–0.82), and (0.000438–0.000838), respectively. A sensitivity study was per-formed to assess the effect of various pH values, drop heights, tailwater depths, stream widths, and sewer ventilation rate levels. The results showed that the emissions concentrations for winter, spring, summer, and autumn reached 3500, 5044, 6425, and 4045 ppm respect-ively. All the emissions levels from this DS can be considered hazardous, and this was particularly evident during the summer months. This study has helped to clarify the fate and emission of hydrogen sulfide gas at the DS by simulation using a TOXCHEM model.