The effect can be very important, even at typical ionic strength encountered in WWTP . It is the case for the crystallization of struvite (63, 71, 72, 73) and calcium phosphate (74, 75, 76). A higher ionic strength decreases the activity of the ions, thus increasing the solubility of minerals. Not considering ionic strength while studying chemical precipitation has led to discrepancies in the solubility measurements of struvite . Its consideration is also relevant to predict and remediate to unwanted struvite precipitation in WWTP . Additionally, a study indicates that the purity of recovered struvite from animal manure was influenced by the ionic strength , which can have a big importance for its further use.