Chlorine contact basin Gravity thickeners nd gravity bell thickener building ry clarifiers Dechlorination Final post-aeration iquid biosolids and effluent pumping BNR Anaerobic Influent pump Actors biosolids Septage station and storage pond receiving screening Fig 4-1 Overview of a biological nutrient removal(Bnr wastewater-treatment plantFig. 4-1 Overview of a biological nutrient removal(BNR) wastewater-treatment plant