Phosphorus Removal
Phosphorus appears in water as orthophosphate (PO4-3), polyphosphate (P2O7), and organically bound phosphorus. Microbes utilize phosphorus during cell synthesis and energy transport. As a result, 10 to 30% of all influent phosphorus is removed during secondary biological treatment.
More phosphorus can be removed if one of a number of specially developed biological phosphorus removal processes is used. These processes are based on the exposure of microbes in an activated-sludge system to alternating anaerobic and aerobic conditions. This stresses the micro-organisms, so that their uptake of phosphorus exceeds normal levels.