Abstract: A biological wastewater treatment system includes a tank or reactor for holding and treating wastewater. Disposed in the tank or reservoir is an array of biofilm carriers for supporting biomass that remove pollutants and contaminates from the wastewater. A screen structure is mounted to the tank for screening treated wastewater flowing from the tank and preventing the biofilm carriers from being discharged from the tank. The screen structure includes a vertical screen made up of a plurality of screen modules disposed in side-by-side relationship and disposed upstream of an outlet formed in the tank. Further this screen structure may include a plurality of auxiliary screens that project form the vertical screen inwardly towards the interior area of the tank thereby providing increased screening area through which wastewater is discharged during a wastewater treatment process.

Abstract: A biological wastewater treatment system includes a tank or reactor for holding and treating wastewater. Disposed in the tank or reservoir is an array of biofilm carriers for supporting biomass that remove pollutants and contaminates from the wastewater. A screen structure is mounted to the tank for screening treated wastewater flowing from the tank and preventing the biofilm carriers from being discharged from the tank. The screen structure includes a vertical screen made up of a plurality of screen modules disposed in side-by-side relationship and disposed upstream of an outlet formed in the tank. Further this screen structure may include a plurality of auxiliary screens that project form the vertical screen inwardly towards the interior area of the tank thereby providing increased screening area through which wastewater is discharged during a wastewater treatment process.