Hybrid bioelectrochemical process enables hierarchical C, N, and P utilization towards negative carbon emission...

Bioelectrochemical system (BES) can provide sustainable solutions for wastewater treatment through lower energy consumption, reduced carbon emissions, and nutrient capture and reuse. Herein, we propose a hybrid bioelectrochemical assembly (HBA)-centered purification-power-cultivation process to achieve hierarchical C, N, and P metabolism, graded power generation, and reusable water production. The hybridization of abiotic and biotic cathode BESs in HBA enables hierarchical C metabolism, with effluent COD directly meeting the Class Ⅲ surface water standard. The customized water-permeable biofilm separators sequentially create anaerobic-anoxic-aerobic zones within HBA, enabling complete N removal. Subsequently, the P-rich tailwater of HBA is channelled into a hydroponic irrigation system for P utilization, ultimately producing reusable clean water. Notably, a high power density of 0.43 W m^-2 is obtained, and this process achieves a net carbon emission of -0.413 kg-CO₂ m^-3. This study presents a prototype for sustainable wastewater purification, particularly in low-resource areas with carbon emission reduction and carbon neutrality targets.