Enhanced Biological Phosphorus Removal

Enhanced biological phosphorus removal (EBPR) is a wastewater treatment configuration applied to activated sludge systems for the removal of phosphate. It is based on the cultivation of special polyphosphate-accumulating organisms (PAO) in the anaerobic tank prior to the aeration tank. These bacteria accumulate large quantities of polyphosphate within their cells resulting in the accumulation of phosphorus in the biomass. The biomass is separated from the treated water at the end of the process and the phosphorus is thus removed. Generally speaking, all bacteria contain a fraction (1-2%) of phosphorus in their biomass due to its presence in cellular components, such as membrane phospholipids and DNA. Therefore as bacteria in a wastewater treatment plant consume nutrients in the wastewater, they grow and phosphorus is incorporated into the bacterial biomass. When PAOs grow they do not only consume phosphorus for cellar components but also accumulate large quantities of polyphosphate within their cells. Thus, the phosphorus fraction of phosphorus accumulating biomass is 5-7%.