Influence of coexisting calcium ions during on-column phosphate adsorption and desorption with granular ferric oxide

•The effect of Ca2+ on column P adsorption was studied with granular ferric oxide.•The intraparticle surface diffusivity of phosphate was 1.0 × 10−11 m2/h.•Phosphate (2 mg P/dm3) was adsorbed effectively when the solution contained Ca2+.•The breakthrough volume (<0.1 mg P/dm3) was 4 times higher with Ca2+ than without.•Pre-treatment with acid increased the efficiency of sorbent regeneration with NaOH.