Hydrogen Exploration as an Energy Source in Electrodialytic Remediation of Sewage Sludge Ash

This research explores the application of electrodialytic extraction of phosphorous from sewage sludge ash (SSA) with a focus on utilizing the hydrogen gas produced at the cathode for energy generation. SSA originates from the incin-eration of sewage sludge from wastewater treatment. It contains both hazardous compounds (e.g., heavy metals) and agriculturally valuable elements (e.g., phos-phorous). This study utilizes an electrodialytic setup involving the application of an electric DC field and the connected electrode reactions. Under varying conditions, the hydrogen production and P extraction are co-optimized. The generated hydro-gen was captured and utilized in a Proton Exchange Membrane (PEM) fuel cell to produce electricity, demonstrating an innovative approach to waste-to-energy con-version. Experiments were conducted using two setups: a two-compartment (2C) and a three-compartment (3C). The 2C design included an additional ion exchange membrane to facilitate ionic migration and prevent metal precipitation on the cath-ode electrode surface. An electrolyte solution of NaNO₃ with different pH and a platinum-coated cathode were tested. Applied currents ranged from 50 mA to 100 mA. Results showed that NaNO₃ 0.01 M solution in the 2C setup gave the highest hydrogen production with a peak voltage of 875 mV in the PEM fuel cell. The findings highlight the significance of an additional ion exchange membrane in reducing ion precipitation and optimizing both hydrogen capture and metal removal. The findings further revealed that hydrogen production was influenced by multiple factors: setup configuration, pH, and applied current. Moreover, the 2C setup performance in P removal was considerably more efficient than the 3C setup. This study explores the feasibility of integrating hydrogen recovery into the electrodialytic recovery process. It offers a sustainable strategy for utilizing SSA, transforming waste into renewable energy, and simultaneously extracting valuable elements such as P.