Mineral-integrated electrochemical system enabling membrane-free pH swing and active chlorine species generation for...

Human urine represents a nutrient-rich reservoir that, if recycled, could significantly offset global fertilizer demands. Yet, its potential remains largely underexploited because rapid urea hydrolysis at the source drives N and P losses via uncontrolled precipitation, while causing pipe clogging and malodor formation. Here, we report a wollastonite (CaSiO₃)-integrated electrochemical alkalization and oxidation (EAO) system that enables concurrent urea stabilization and phosphorus recovery. Anodic proton-driven dissolution of CaSiO₃ releases Ca²⁺, which combines with cathodically generated alkalinity to promote phosphate precipitation, whereas anodic oxidation suppresses urease-mediated urea hydrolysis. We show that the driving force lies in the microenvironment near the electrode, which has distinct pH, Ca²⁺ and active‑chlorine gradients. Treating two‑fold diluted urine at 12 A m^-2 yields the most energy‑efficient scenario (20.11 kWh kg^-1 P, 2.99 kWh m^-3 urine), achieving 96.0% phosphate recovery and robust urea stabilization in real urine. We expect the EAO system to create a scalable electrochemical route to close nutrient loops in decentralized sanitation, supporting sustainable fertilizer production and urine management.