RO pretreatment cooling tower filtering cooling water filter RO PRETREATMENT In addition to cooling and heating applications, we developed a number of unique approaches for polishing water of specific applications such as: Water polishing for RO pretreatment of reverse osmosis systems Effluent treatment - removing suspended solids to meet discharge limits Water reuse and zero discharge package Water polishing for green buildings (rain water) Recreational, Snow Making, Olympic Pools, Aquaculture VORTISAND® is also very effective as RO pretreatment systems. The VORTISAND® filters have proven themselves for more than 35 years and are the result of many years of research and development.