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

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.