Evaluating operational efficiency and hydrogen sulfide mitigation in fluidized bed co-gasification of sewage sludge

Abstract

This study investigated the operational efficiency and in situ H₂S mitigation of municipal sludge (MS) co-gasification with drinking water treatment sludge (DWTS) in a lab-scale fluidized-bed reactor. Gasification experiments were performed at 700–900 °C, ER 0.2–0.4, and 10–20 wt% DWTS addition. Increasing temperature and DWTS ratio enhanced syngas production and reduced tar yield. The highest syngas yield for MS alone was 79.10% at 900 °C and ER = 0.2, while co-gasification with 20 wt% DWTS increased syngas yield to 87.12% and reduced both heavy and light tars substantially. Under the same conditions, DWTS achieved a maximum H₂S removal efficiency of 70.08%, attributed to the reaction of iron oxides in DWTS with H₂S to form stable iron sulfides. XRD analysis and thermodynamic modeling confirmed that sulfur capture shifted toward phases ZnAl₂S₄, FeS, MnS, K₂S, CaS, and Al₂S₃ as DWTS loading increased. These results demonstrated that DWTS is a promising waste-derived catalyst for improving gasification performance and reducing sulfur emissions in sludge-to-energy systems.