Surface-modulated 3-dimensional carbon electrode with high phosphorus releasing efficiency from municipal sludge

This study addresses two critical challenges in electrochemical phosphorus recovery from waste activated sludge (WAS), low conductivity and insufficient radical generation. Through surface modulation, a waste-derived methyl/hydroxyl co-functionalized 3-dimensional (3D) carbon electrode was innovatively developed from waste phosphorus-free epoxy resin, establishing a sustainable "waste-treats-waste" strategy. The unique CH₃/OH dual functional groups on the electrode synergistically enhanced hydroxyl radical (*OH) generation, promoting the conversion of organic phosphorus to inorganic phosphorus. Moreover, the enhancement of *OH was quantitatively confirmed by density functional theory (DFT) calculations, demonstrating a more negative Gibbs free energy change (ΔG) for *OH formation on ERC-CH₃/OH during electrolysis. Experimental results of the lab-scale system performed a 76.39% organic-P conversion and an 81.41% total-P release (13.98% increase over the control) with a low energy consumption (5.24 kWh/kg P). Pilot-scale tests exhibited scalability with 79.07% P-release efficiency and operational stability. This work provides both functional material solution and mechanistic insight for advanced sludge resource recovery.