Phosphorus removal and recovery from fosfomycin pharmaceutical wastewater by the induced crystallization process

The excessive release of phosphorus is a main cause of eutrophication, but phosphorus itself is an important non-renewable resource. If phosphorus could be recovered from wastewater, it can not only reduce the pollution, but also reach the aim of resource recycle. An induced crystallization process was combined with the schorl/H₂O₂ system to remove and recover phosphorus from the fosfomycin pharmaceutical wastewater. Firstly, in the schorl/H₂O₂ heterogeneous Fenton system, the organic phosphorus (OP) in fosfomycin pharmaceutical wastewater was transformed to the inorganic phosphorus (IP), and then IP was recovered by hydroxyapatite (HAP) induced crystallization process. In sequence batch reactors (SBR), the entire crystallization process went through 60 cycles, and each of the cycle lasted for 12 h, including 2 h for reaction and 10 h for sedimentation. The influence of different initial pH values, which were 8, 9, 10 and 11, on the induced crystallized product was investigated. The morphology and structure of the induced crystallized product were analysed. The results indicated that when the pH value was about 8, most of the recovery products was in the form of dicalcium phosphate anhydrous (DCP, CaHPO₄). At pH 9 the recovery products were mainly DCP and HAP. As pH increased to 10 or 11, most of the recovery products would be HAP and calcium carbonate. Carbonate involved in the crystallization reaction, especially at pH 11.