A filtration system for water or other selected liquids that includes an ozone mixing station, a primary solids and gas separator and, if desired, a second vortex particle separator and filter system. The ozone mixing station includes a high efficiency ozone generator and a channel arrangement, such as a spiral tubular treatment coil, through which the ozone/liquid mixture passes to assure thorough mixing and provide time for effective treatment. The primary solids separator includes an offset inlet jet through which the liquid from the ozone treatment station is injected into a first circular chamber. The resulting rotating liquid vortex moves to a narrowed co-axial second circular chamber to cause heavy particles to concentrate at the outer perimeter then to a coaxial larger third circular chamber. The liquid exits through an annular outlet located around the chamber axis to prevent buoyant particles in the axial region and heavy particles at the outer periphery from passing out with the liquid. Gas collects in a cylindrical axial region with the lighter suspended particles in an annular region around the gas column. The gas phase is removed through an annular, variable, series of holes at the top of the chamber. The liquid from the solids separator may be passed to a filter system to further treat the liquid.