Synergistic removal of carbon and phosphorus by modified carbon-based magnetic materials

Aiming at the issues of high consumption of reagents and energy, and poor removal ability of carbon and phosphorus in the existing process of sewage treatment plants, a novel type of carbon & phosphorus co-trapping magnetic coagulant named as acid-modified magnetically doped biochar (A/M-BC) was prepared for sewage treatment. Results showed that the removal efficiencies of chemical oxygen demand (COD) and total phosphorus (TP) were as high as 64.4 % (±2%) and 93.7 % (±8%), respectively. A series of characterization findings indicated that the A/M-BC had a nanoscale porous structure, a surface laden with magnetic particles, and a diverse array of iron oxides, enabling the formation of phosphate complex groups and exhibiting excellent paramagnetism. The efficient co-trapping of carbon and phosphorus by A/M-BC was mediated via combined coagulation and adsorption. Where into, coagulation includes co-precipitation and bridge of phosphate-iron complexes induced by complex ferric salts and net sweep trapping with magnetic powder. The novel magnetic coagulant A/M-BC had the advantages of a better co-trapping and faster separating for carbon and phosphorus, which has great application potential in reducing carbon emissions in the sewage treatment process. © 2024 Elsevier B.V.