Chitosan Coupled with Electroflotation for Phosphorus Recovery from Eutrophic Taihu Lake Water
Algal-derived phosphorus (P) constitutes a significant fraction in eutrophic lakes, with particulate phosphorus (PP) serving as both a major internal P reservoir and a potential target for P resource recovery. This study proposed a chitosan-coupled electroflotation (CEF) technology for efficient enrichment and recovery of algal-derived P from high-algal water. Using Taihu Lake algae-laden water as the test medium, the effects of chitosan dosage and voltage on the enrichment of different P fractions were systematically evaluated. Results showed that the optimal P enrichment was achieved at a chitosan dosage of 15 mg·L−1, and higher voltages further enhanced the enrichment efficiency. Under optimal conditions, PP accounted for 83.57% of the enriched P, indicating a strong capability for particulate P capture. The mechanism involved chitosan-induced flocculation via charge neutralization and sweep flocculation, while higher voltages increased the positive charge density of chitosan molecules, enhancing charge neutralization and electroflotation. In P release experiments, open conditions significantly promoted the transformation of PP to dissolved P, whereas closed conditions inhibited this process. Additionally, chitosan's antibacterial action and physical retention effectively limited P release. Compared with conventional metal salt coagulants, this method avoids metal ion residues, offering high environmental safety and providing a green and feasible approach for the harmless disposal and resource utilization of algal-derived P in eutrophic lakes.