Stabilization of Source-Separated Urine Using Electrochemically Synthesized Hydrogen Peroxide

Abstract

Separate urine collection and treatment is an attractive alternative to current wastewater treatment strategies, though urea hydrolysis presents challenges for collection and storage. In this study, we demonstrated proof-of-concept for a method to stabilize source-separated urine with electrochemically synthesized hydrogen peroxide (H2O2). Samples of synthetic urine were stored following electrochemical treatment and monitored for changes in total ammonia nitrogen (TAN), H2O2, and pH. TAN formation from urea hydrolysis was inhibited by the deactivation of the urease enzyme by H2O2 in all experiments. We evaluated the effects of current density, treatment time, and final pH of the synthetic urine. Higher current densities and longer treatment times resulted in slightly lower final concentrations of TAN, while pH had no observable effect on final TAN concentrations. A neutral pH resulted in a slower degradation of H2O2 within treated samples compared to alkaline samples. Direct urea measurements showed that as much as 78.9% of the initial urea was preserved after 140 days of storage at room temperature. These results confirm that electrochemically synthesized H2O2 is an effective method for source-separated urine stabilization and present a basis for investigating this process beyond bench-scale experiments.