Thinning the oil with water hanging dome can be used for slow sand filtration, rapid sand filter, filter for single-or multi-media filter, to filter city water, industrial water or industrial wastewater, water can also be linked to the oil film thinning the ball do microbial carrier, composed of biological filter, the use of membrane filter layer formed on the surface to purify wastewater. The technology can be applied to the treatment of organic industrial wastewater, but also for urban water supply contaminated water pretreatment, the ideal material to address the biological nitrogen and phosphorus in water filter. Thinning the oil with water biofilm characteristics of the ball with hydrophobic edible vegetable oil can be used for coarse-grained devices or other mechanical filter oily wastewater treatment. In the ion exchange treatment of industrial wastewater or water softening, desalination, high pure water, the dredging of oil hanging dome of water can be fixed bed countercurrent regenerated resin cushion, cushion particle diameter 1-32mm, thinning the oil with water hanging dome also has a role in addition to manganese, iron effect at 90% or more, especially for deep wells in the North except iron and manganese, its operating methods and other media except iron and manganese (Mn sand) is similar.