While chemical precipitation and enhanced-biological removal are the two main routes for P removal, adsorption on iron oxides is a possible mechanism in some cases. It appears that ionic strength favourably influences this process in the range of (0.001-0.1M) . The importance of ionic strength may even be higher for membrane-based treatments than for conventional treatment since it was found to have an impact on the membrane fouling in MBR reactor . Lastly, ionic strength variation and absence of activity correction led to significant differences in predicted process performance evaluated with anaerobic digestion models .