Obtaining High Yield Hydrogen from Sewage Sludge by Two-Stage Gasification: Alkaline Pyrolysis Coupled with Catalytic Reforming

Abstract

Municipal sludge is a sizable byproduct of sewage treatment plants, and its treatment and disposal need to agree with both environmental protection and resource utilization policies. In this study, municipal sludge was treated to produce hydrogen as a resource. A two-stage reactor was employed, and alkaline pyrolysis was coupled with ex-situ catalytic gasification and optimized to promote hydrogen production from sludge. The gas production characteristics were analyzed under different gasification parameters, and the catalyst was characterized following the reaction. Optimal gasification conditions were found at a steam flow of 5 mL h –1 in which 34.23 mmol g –1 of hydrogen was produced from dry sludge. Results suggested that the increased amount of hydrogen produced was due to promoting the water gas shift reaction. A brief economic analysis showed that this process is feasible for use in future industrial applications and provides an effective process route for the resource treatment of sludge.