Valorization of MSWI bottom ash for biogas desulfurization: Influence of biogas water content

In this study an alternative valorization of Municipal Solid Waste Incineration (MSWI) Bottom Ash (BA) for H₂S elimination from landfill biogas was evaluated. Emphasis was given to the influence of water content in biogas on H₂S removal efficiency by BA. A small-scale pilot was developed and implemented in a landfill site located in France. A new biogas analyzer was used and allowed real-time continuous measurement of CH₄, CO₂, O₂, H₂S and H₂O in raw and treated biogas. The H₂S removal efficiency of bottom ash was evaluated for different inlet biogas humidities: from 4 to 24g_water/m³. The biogas water content was found to greatly affect bottom ash efficiency regarding H₂S removal. With humid inlet biogas the H₂S removal was almost 3 times higher than with a dry inlet biogas. Best removal capacity obtained was 56gH₂S/kgdryBA. A humid inlet biogas allows to conserve the bottom ash moisture content for a maximum H₂S retention.