Removal of Fe²⁺ in coastal aquaculture source water by manganese ores: Batch experiments and breakthrough curve modeling

Excessive Fe²⁺ in coastal aquaculture source water will seriously affect the aquaculture development. This study used manganese sand to investigate the removal potential and mechanism of Fe²⁺ in coastal aquaculture source water by column experiments. The pseudo-first-order kinetic model could better describe Fe²⁺ removal process with R² in the range of 0.9451-0.9911. More than 99.7% of Fe²⁺ could be removed within 120 min while the removal rate (k) was positively affected by low initial concentration of Fe²⁺, high temperature, and low pH. Logistic growth (S-shaped growth) model could better fit the concentration variation of Fe²⁺ in the effluent of the column (R²>0.99). The Fe² breakthrough curve could be fitted by Bohart-Adams, Yoon-Nelson, and Thomas models (R²>0.95). Smooth slices with irregular shapes existed on the surface of manganese sand after the reaction while Fe content increased significantly on the surface of manganese sand after the column experiment. Moreover, FeO (OH) was mainly formed on the surface of manganese sand after the reaction. PRACTITIONER POINTS: Fe²⁺ in coastal aquaculture source water could be removed by manganese ores. The pseudo-first-order kinetic model better described the Fe²⁺ removal process. FeO (OH) was mainly formed on the surface of manganese sand after the reaction.