Evaluating the potential severity of biogas toxic release, fire and explosion: consequence modeling of biogas dispersion in a large urban treatment plant.

Objectives. Biogas production in treatment plants for energy generation has increased in recent years. This study aimed to model the consequence of biogas release in a large urban treatment plant. Methods . The study modeled biogas storage tank consequences in a large urban treatment plant in Iran. Due to potential for biogas harmfulness, three consequences of toxic release, fire and explosion were evaluated. Scenarios were evaluated in the worst-case situation. All modeling steps were performed using PHAST version 7.2. Results. In the case of catastrophic reservoir rupture in summer, distances of 3788.94, 128.86 and 91.72 m from the reservoir in the wind direction will be in the range of 100, 500 and 1000 ppm biogas, respectively. Study of pressure values due to explosion in the catastrophic rupture scenario revealed that distances of 57.19, 14.70 and 115.84 m from the biogas reservoir were in the range of 0.02, 0.13 and 0.2 bar pressure increase, respectively. Conclusion. Due to the treatment plant's location in a dense urban area, biogas dispersion could lead to exposure of many people to high-risk areas. Therefore, taking control measures comparable with the consequence modeling output can be a practical step toward reducing vulnerability against such incidents.