Mg tailings composite biochar for aquaculture effluent treatment: Priority response, electrostatic regulation and synergistic adsorption

Converts WD and IT into efficient adsorbent MBMS, achieving dual waste valorization. • Innovative “adsorb-modulate-capture” strategy enables synergic MB and Cu 2+ removal. • MBMS is a highly effective adsorbent towards dual pollutants with > 99% removal rate. • MBMS has good recyclability and can be used as soil fertiliser after deactivation. The Cu 2 + and methylene blue (MB) composite pollution generated by the intensive production model adopted in recirculating aquaculture systems has become a critical challenge requiring urgent solutions in the field of fishery environmental remediation. Existing remediation technologies commonly suffer from issues such as competitive adsorption of pollutants, poor structural stability, and limited electron transfer, making it difficult to achieve efficient synergistic treatment of composite pollution systems. This study utilized waste dander (WD) and Mg slag tailings (IT) as raw materials to prepare a novel adsorbent (MBMS) through an impregnation-calcination-ball milling-recalcination process. Based on the pathway strategy of “priority response, electrostatic regulation and synergistic adsorption” it achieved highly efficient, synergistic, and stable treatment of Cu 2+ and MB co-pollution in aquaculture effluent. Adsorption experiments demonstrate MBMS exhibits outstanding synergistic treatment efficacy for Cu 2+ and MB composite pollution, achieving removal rates of 99.27% for Cu 2+ and 99.79% for MB. This study further elucidates the interaction mechanisms and synergistic treatment pathways through electrostatic potential, charge distribution, density of states, and frontier molecular orbital analyses. Additionally, spent MBMS was utilized as soil fertilizer in alfalfa cultivation experiments to evaluate its value-added application potential. This research not only provides a novel approach for solid waste reduction and high-value utilization of WD and IT but also offers a technically viable solution for the synergistic treatment of Cu 2+ and MB composite pollution in aquaculture effluent, delivering both environmental benefits and practical application value. Download: Download high-res image (277KB) Download: Download full-size image