This study demonstrates that the chemical energy contained in human urine can synergize the in situ nutrient recovery and purification of urine itself. This process was achieved using a urine-powered microbial electrochemical system named U-Power, which can provide a maximum power density of 21.3 W m−3via the degradation of fresh human urine. Urea hydrolysis was induced by anodic microorganisms and further accelerated by the electrical potential inside U-Power to provide ammonium and balance the pH in the anode. Driven by the electrical potential generated by U-Power, the NH4+ and PO43− contained in urine migrated into the high nutrient concentration recovery solution. On average, 93.8% of organics, 73.1% of nitrogen and 86.2% of phosphorus were removed, along with recovery concentrations of 1234 mg L−1 nitrogen and 101 mg L−1 phosphorus. Both the above purification and recovery processes require no energy input but output a satisfactory power density among all present urine treatment studies, together with an average current efficiency of 178% and a coulombic efficiency of 26%. By achieving the triple benefits of energy-positive recovery of nutrients from urine, avoiding the complicated and energy-intensive process of nutrient removal in downstream wastewater treatment facilities, and avoiding the energy and hygiene issues combined with the storage and reuse of urine, U-Power represents a promising tool to pave the way for a sustainable water–energy–nutrient nexus.
