Phosphorus Resource Recovery Based on a Bio-electrodialysis System

Abstract

Phosphorus is a non-renewable yet essential nutrient, making its recovery from wastewater crucial for resource sustainability and aquatic environmental protection. This study developed a three-chamber bio-electrodialysis (BED) system to investigate the effects of influent phosphorus concentration (155–1550 mg/L), NaCl concentration (0–12 g/L), and applied voltage (0.4–0.8 V) on phosphorus migration, enrichment, and organic matter removal. Under 155 mg/L influent and 0.8 V, the system achieved a maximum phosphorus enrichment ratio of 657% and 96.4% COD removal, whereas high-phosphorus influent (1550 mg/L) reduced enrichment to 229% due to intensified ionic competition. Moderate NaCl (≤6 g/L) enhanced conductivity and ion flux, while 12 g/L inhibited PO₄³⁻ transport through Cl⁻ competition. Voltage elevation enriched electroactive taxa such as Gemmatimonadota and hydrogenotrophic Methanoregula, resulting in distinct anode–cathode community differentiation. SEM-EDS analysis demonstrated that pH 5–7 favored the formation of well-crystallized iron phosphate with near-theoretical Fe–P–O ratios, whereas pH 3 and pH 9 yielded poorly structured precipitates. These findings establish a coupled mechanism integrating electric-field-driven ion transport, voltage-regulated microbial cooperation, and pH-controlled crystallization, providing mechanistic insight and operational guidance for phosphorus recovery using BED systems.