Orthophosphate removal from domestic wastewater using limestone and granular activated carbon

► Limestone has ability to adsorb 98% PO4-P from aqueous solution at optimum conditions. ► Freundlich and Langmuir isotherms both provided comparable correlation coefficient values. ► Adsorption kinetics shows good compliance with the pseudo-second-order kinetics model. ► It indicates that the adsorption is chemisorption. ► Higher flow rate and pH yielded shorter column saturation time in upflow column study.