Patent ID: 7008538
Filing Date: 2006-03-07
Classification: C02F

Abstract:
1. A process for treating wastewater containing liquid and solids, comprising the steps of: providing a process vessel for containing said liquid and solids; establishing a plurality of zones in an upper portion of said processing vessel including an aerobic zone, an anoxic zone and a clarification zone; feeding the wastewater into said processing vessel including said plurality of zones; maintaining aerobic conditions in said aerobic zone; maintaining anoxic conditions in said anoxic zone; maintaining clarification conditions in said clarification zone; maintaining a facultative zone in a middle portion of said process vessel below said aerobic zone, said anoxic zone and said clarification zone; maintaining an anaerobic zone in a lower portion of said processing vessel below said facultative zone; supplying air into said aerobic zone and creating an upflow in said aerobic zone; causing said upflow from said aerobic zone to create a downflow into said anoxic zone; causing a first portion of said downflow from said anoxic zone to pass into said upflow of said aerobic zone; causing a second portion of said downflow from said anoxic zone to create an upflow into said clarification zone; withdrawing substantially clarified liquid from said clarified zone; and causing settling of a portion of said solids from said plurality of zones into said anaerobic zone; and withdrawing substantially solids from about the bottom of said anaerobic zone.