Enhancing nutrients recovery from source-separated urine through a novel bioelectrically assisted forward osmosis coupled with gas permeation membrane system: reaction kinetics and mechanisms

Effective nutrient recovery from source-separated urine is essential for sustainable resource management and water pollution control. In this study, we developed an innovative bioelectrically assisted forward osmosis coupled with a gas-permeation membrane system (BFGS) to simultaneously recover nitrogen and phosphorus from urine. The BFGS substantially improved nutrient recovery efficiency, achieving 80.44 % nitrogen and 99.92 % phosphorus recovery. Relative to a control system without an electric field, the electric field accelerated the kinetics of nitrogen and phosphorus recovery by factors of 1.25 and 1.22, respectively. Electronic equilibrium analysis revealed that the BFGS achieved optimal electronic balance, facilitating efficient oxygen reduction reaction and minimizing electronic losses. Partial least squares path modeling further identified electric field–assisted forward osmosis as the primary driver of nutrient recovery. Mechanism exploration disclosed that the BFGS enabled simultaneous nitrogen and phosphorus recovery by inducing ion migration by the electric field while exploiting the reverse salt flux of the FO membrane. This work offers novel insights into nutrient recovery using the BFGS and highlights its remarkable efficiency and feasibility for sustainable management of source-separated urine.