A method uses anionic and cationic polymers added in, any order or simultaneously, to aqueous media for the removal of substances. The sequential addition of the two biopolymers, anionic xanthan, followed by cationic chitosan, causes the rapid formation of very large and cohesive fibrillar aggregates that may exhibit high solids to liquid ratios and that quickly settle out from the aqueous media. The aqueous media can be easily separated from the large fibrillar aggregates by settling under gravity or by filtration through a porous containment device, such as a synthetic or non-synthetic woven or non-woven fabric including a geotextile fabric or a solid containment device containing a solid mesh screen.