Municipal wastewater effluents containing phosphorus accelerate eutrophication in receiving waters in which phosphorus is the limiting nutrient. For this reason, wastewater effluent phosphorus control is important in many regions. Although chemical precipitation is a proven technology capable of meeting phosphorus discharge restrictions, the production of considerable quantities of chemical sludge has created disposal problems. Disposal processes such as incineration and land application are limited in their ability to handle chemical sludges. Biological phosphorus removal would seem to provide a more cost-effective and environmentally sound means of removing phosphorus from wastewater effluents because it eliminates or greatly reduces sludge disposal problems.