Valorization of urban biosolids for sustainable hydrogen production through steam gasification over silicon oxide sand

The present work addresses sustainable development and energy goals by investigating the valorization of urban biosolids into clean Hydrogen (H2) through steam gasification in a fluidized bed reactor at 850°C. From a materials science standpoint, the study employs silicon oxide (SiO2) as a low-cost and inert bed material. This latter was selected thanks to its high thermal stability and ability to ensure optimal fluidization, which is crucial for reactor hydrodynamics. The generated syngas analysis revealed high yield of H2 and CO (22.05 and 372.53 g/Kg of raw urban biosolids respectively), confirming significant organic matter conversion. The residual hydrocarbons yield was found relatively high (up to 20 vol%), due to incomplete steam reforming, notwithstanding, steam effectively cracked heavy components into lighter, usable gases. The elevated CO2 generation provides also a clear opportunity for Carbon Capture and Reutilization for miscellaneous application. This research demonstrates the technical and material feasibility of a novel waste-to-energy solution, offering a direct, interdisciplinary contribution to energy, sustainable development, and materials science.