Adsorption in the continuous mode plays a significant role in wastewater treatment. In this study, Mimosa pigra-derived biochar modified with 2 M AlCl3 salt was used to pack a lab-scale column to eliminate PO43− from aqueous solutions. The influence of the operational factors, such as inlet PO43− concentration (25–100 mg/L), flow rate (6–18 mL/min), and biochar bed height (1.5–4.5 cm), on the breakthrough curve was evaluated. The kinetic models of Adam–Bohart and Yoon–Nelson were utilized to analyze the experimental results. The best conditions were determined to be the influent PO43− strength of 50 mg/L, injection speed of 6 mL/min, and column height of 4.5 cm. These results can be applied in the design of large-scale columns for the sequestration of PO43− from wastewater. Display omitted •Phosphate was successfully removed using fixed-bed modified biochar column.•The inlet PO43−, flow rate, and bed height affected the breakthrough curve.•The optimal conditions were 50 mg/L of PO43−, 6 mL/min flow rate, and 4.5 cm height.•Adam–Bohart and Yoon–Nelson models were utilized to describe experimental results.