The present invention provides improved methods for purifying and/or removing multiply charged cations and suspended solids from water. In particular the process relates to an additive composition that has the appropriate surfactant characteristics for effectively removing multiply charged cations and suspended solids from an aqueous or oil/aqueous mixed phase via foam fractionation. According to the invention, a hydrophobically modified polymer that acts as an associative thickener is used in the presence of a source of alkalinity or anionic reactant as well as surfactant in appropriate ratios to facilitate multiply charged cation and suspended solids removal for water purification in any of a number of commercial, environmental and industrial applications.