Phosphorus recovery using a crystallization process for Sewage Treatment Plant

A novel phosphorus recovery process enabling an effective reuse of recovered phosphorus as a resource has been developed. Three processes, which match the characteristics (sewage component, concentration and flow rate, etc.) of the waste water or the sludge generated form sewage treatment, are introduced here. Verification tests carried out using a crystallization of magnesium ammonium phosphate revealed a phosphorus crystallization exceeding 85%. Moreover, these tests show that the recovered phosphorus can be reused as a fertilizer. Another verification test carried out using a crystallization of hydroxylapatite revealed that the phosphorus concentration is reduced to a few milligrams per liter. In addition it is found that the recovered hydroxylapatite can be reused as a phosphorus ore. Each of the three processes is revealed to contribute to prevention of water contamination, as well as the recovery of phosphorus as a resource.