Patent ID: 8499832

Claim:
A method for filtering a fluid comprising water, at least one surfactant and fine solids, the method comprising contacting the fluid with substrate particles bearing comparatively smaller particulate additives thereon, thereby removing at least a portion of the fine solids therefrom to give a filtered fluid containing the surfactant, where the particulate additives are present in an amount effective to remove at least a portion of the fine solids from the fluid, where the particulate additives: have a mean particle size of 1000 nm or less, and are selected from the group consisting of alkaline earth metal oxides, alkaline earth metal hydroxides, alkali metal oxides, alkali metal hydroxides, transition metal oxides, transition metal hydroxides, post-transition metal oxides, post-transition metal hydroxides, piezoelectric crystals, pyroelectric crystals, and mixtures thereof.