The hazard of sour gas produced in anaerobic digestion plants

Biogas has been recognized to be an alternative energy source to conventional fossil-fuel. It is a way to reduce waste and get energy at the same time. Anaerobic Digestion plants are the main biogas producers, but many safety issues are linked to the process of converting organic matter into energy source. This work of thesis is focused on the hazard of sour gases, hydrogen sulphide and methane in particular, which are biogas-based constituents. The hazard evaluation was conducted to identify the impact, in terms of humans and environment; the characterization and the quantification of the critical effect zone has been carried out. The case studies were evaluated by means Phast programme, a hazard analysis software, and through simulations on the CFD-Computational Fluid Dynamic software, ANSYS FLUENT. Three case studies were implemented, considering mixture compositions of methane and hydrogen sulphide, present in different percentage. The results obtained show that toxicity is the main issue of biogas release in terms of safety distance if the hydrogen sulphide concentration is relevant.