Synergistic Electrocoagulation-Bioaggregation for Efficient Phosphorus Removal: Pilot-Scale Engineering Validation

Conventional phosphorus removal technologies are plagued by inherent challenges, including high energy consumption and secondary pollution. This study presents an innovative in situ inorganic–organic hybrid electrocoagulation dephosphorization (IOED) technology, which integrates aluminum electrocoagulation with microbial aggregation. At an applied voltage of 2.5 V, the IOED generates aluminum-sludge aggregates that reduce PO43– from 5 mg L–1 to <0.5 mg L–1 within 4 h─exhibiting a PO43– removal efficiency 5-fold higher than that of conventional biological methods. Moreover, this technology reduces turbidity by promoting the secretion of extracellular polymeric substances while preserving microbial activity and community structure integrity. The innovation extends to the screened Mg–Zn–Cu-doped aluminum electrode, which cuts energy consumption by 44% and optimizes the Al/P molar ratio to 1.24, thereby significantly improving sustainability and cost efficiency. A 100 day continuous pilot-scale device (treatment capacity: 500 m3 d–1) demonstrated the technology’s long-term robustness, with effluent total phosphorus concentrations consistently maintained below stringent discharge limits (≤0.5 mg L–1) without compromising sludge settleability or microbial activity. Notably, the IOED system eliminates the need for chemical additives, reduces sludge production by 0.036 kg per m3 of treated wastewater, and operates without secondary sedimentation units, offering a maintenance-free solution for both decentralized and large-scale applications.