In alum sludge-based CWs ligand exchange has been identified as the primary mechanism of phosphate removal. During the course of the study a constant hydraulic loading rate of 0.28 m3/m2 d was applied to the CW-MFCs with average influent SRP concentrations of 4.12 mg/L. By considering the average removal efficiency of 88%, then 2643 mg-SRP was removed during the 90 day testing period or 0.30 mg-SRP/g-sludge equating to 1.22 mg-SRP/ g-sludge per year