From interfacial stabilization to maintainable operation: fouling-resilient synthetic urine valorization by bipolar membrane electrodialysis.

Bipolar membrane electrodialysis (BMED) is a promising route for urine valorization, yet practical deployment is constrained by organic-inorganic synergistic fouling that drives tipping-point instability, accelerating efficiency decay and neutral-solute "sieving failure" beyond fixed-interval maintenance. Here we propose a mechanistically grounded, condition-oriented maintenance framework linking interfacial stabilization to early-warning prognosis and periodic recovery using process-derived chemicals. Across antiscalant dosages (0-200 mg L-1) in synthetic urine, a biodegradable poly(aspartic acid)-based antiscalant (PASP-SEA-ASP) reveals a clear stability window: 100 mg L-1 maintains desalination efficiency above ∼80% over multi-batch operation and mitigates protein-induced sieving failure, increasing urea-dominated total-N recovery from 84.51% to 91.51%, whereas a supra-optimal dosage (200 mg L-1) deteriorates faster. This dose optimization also prolongs the estimated cleaning interval from 9 to 13 batches (∼30%). Interfacial analyses attribute the non-monotonic behavior to dual-interface reconstruction-competitive protein displacement on the anion-exchange membrane and formation of a net-neutral shielding barrier on the cation-exchange membrane-preserving interfacial integrity under dynamic pH and weakening protein-cation synergy. Because breakdown remains intrinsically stochastic, we operationalize proximity to failure by extracting early-stage conductivity kinetics (0-20 min) as an actionable proxy to prognose batch-end desalination performance across dosing conditions, with the conductivity slope emerging as the dominant descriptor. Finally, as a 10-batch maintenance demonstration, recycling BMED-generated acid/base streams enables in situ regeneration, thereby restoring desalination performance to 94.37% of the pristine baseline. Together, these results translate interfacial control into maintainable operation and suggest a pathway to reduce reliance on externally supplied cleaning chemicals for urine BMED valorization.