Patent ID: 7258798
Filing Date: 2007-08-21
Classification: C02F

Abstract:
1. In a method of treating raw water with a package plant to produce potable water, said package plant including an inlet for receiving water to be treated, an ozonator for disinfecting said water, a contact column to permit ozone from said ozonator to mix with said water, said contact column having a vent to remove free ozone from said water before said water is directed to an upflow roughing filter, said upflow roughing filter including at least one lower coarse filter media and at least one upper less coarse chemically activated carbon filter media in the roughing filter, a downflow slow sand filter, wherein said upflow roughing filter and downflow sand filter are located in a common tank, said method including: stopping the flow of water to the inlet; draining water from said common tank through said roughing filter; flowing wash water up through said roughing filter to agitate and expand said upper activated carbon filter media of said roughing filter; flowing the wash water through an associated wash trough in said common tank and causing said unwanted material to flow into said associated wash trough, thereby removing said unwanted material from said common tank without fouling said slow sand filter; and washing the slow sand filter.