Nutrient removal from wastewater has become an important concern because of increased occurrence of eutrophication in surface water bodies. Nitrogen and phosphorus both are responsible for eutrophication. Eutrophication is the natural aging process of a body of water as biological activity increases. Eutrophic water is characterized by high concentration of aquatic weeds and algae. These organism eventually die, sink to the bottom, and decay. Consequently, this cycle increases the sediment oxygen demand, which decreases the dissolved oxygen in the lower water levels. Additionally, eutrophication is enhanced by the large day night cycling of dissolved oxygen that accompanies increase photosynthesis and respiration. The acceleration of eutrophication is directly linked to increasing nutrient loading from sewage treatment plant discharges.