Eutrophication of lakes and other natural bodies of water, caused by the presence of excess nutrients, is a growing problem. Phosphate is delivered to surface and ground water as a result of agricultural and feedlot run-offs, and municipal and industrial wastewaters. Treatment of domestic and agro-industrial wastewater often releases large amounts of phosphorus and nitrogen into water. Excess phosphorous concentration (>1.0 mg/L P) in water bodies causes eutrophication of aquatic ecosystems, which results in deterioration of water quality (Smith 2003). Therefore, it is important to reduce phosphorous concentrations in water to improve water quality.
On the other hand, phosphorus is essential for plant growth and is an important constituent of agricultural fertilizers. Phosphorous is typically obtained by mining inorganic phosphate rock, such as apatite, followed by chemical treatment to produce phosphoric acid, thereby generating phosphate. These natural supplies of inorganic phosphate are, however, diminishing. With increasing world population the demand of phosphorous for food production is estimated to peak sometime between 2030 and 2040. It is predicted that world phosphorous production will begin to decline around 2035. The consequent possible shortfall of phosphorous fertilizers is a major concern for global food security.
Methods for removing phosphate from agricultural, municipal and industrial wastewater are known, but they often result in the production of a solid, insoluble phosphate fraction that is not amenable to recycling or reuse (de-Bashan et al., 2004, Water Res 38:4222-4246).