H2S Adsorption from Biogas with Thermal Treatment Residues

Abstract

Biogas cleaning is a fundamental step before its exploitation to take off potential pollutants, particularly hydrogen sulfide (H2S), from the gas and therefore to protect downstream facilities while reducing toxic emissions in the atmosphere. The aim of the presented work is to compare H2S adsorption efficiencies between different types of thermal treatment residues: a biochar, two biomass ashes and an incinerated sewage sludge. H2S-adsorption experiments were realized with a real landfill biogas. All materials were characterized before and after adsorption in order to evaluate their physicochemical properties related to their reactivity. The results showed that biochar and biomass ashes can both remove H2S from biogas, despite these materials have very different features. Biomass ashes are basic, humid and mineral materials, whereas biochar is dry, mainly organic and very porous. On the contrary, incinerated sewage sludge could adsorb only a small amount of H2S under tested experimental conditions, underlining the importance of the porosity of materials for sufficient H2S adsorption. The use of thermal treatment residues for biogas cleaning has a positive impact on the environment with the reuse of waste material and can also reduce the costs of biogas as an energy vector and enable its development.