Study on treatment of amino trimethylene phosphonic acid from wastewater and simultaneous phosphorus recovery by Fenton process

Removal and recovery of amino trimethylene phosphonic acid (ATMP) commonly used as scale inhibitor in industrial wastewater is of great significance for water protection and sustainable utilization of phosphorus resources. The Fenton method was used to treat ATMP in wastewater. The treatment performance of ATMP by ferrous sulfate (FeSO₄), hydrogen peroxide (H₂O₂), and Fenton methods(FeSO₄+H₂O₂) was compared. Furthermore, the effects of FeSO₄ concentration, H₂O₂ concentration, initial solution pH, initial ATMP concentration, and coexisting ions on the treatment of ATMP in the Fenton method system were investigated. The results showed that when the initial concentration of ATMP was 1.0 mmol/L (in P), the dosage of FeSO₄ was 1.5 mmol/L, the dosage of H₂O₂ was 1.5 mmol/L, and the initial solution pH was 3, the oxidation treatment effect of ATMP was relatively high. The total phosphorus (TP) removal rate was as high as 95% after 30 min of reaction time, and the removed TP was generated in the form of ferric phosphate (FePO₄) precipitation for phosphorus recovery. The coexisting metal cations (Ca²⁺ or Mg²⁺) had no effect on the oxidative degradation of ATMP. while the coexisting inorganic anions (\mathrmHCO_3^- or \mathrmNO_3^- ) and organic anions (C₅H₇O₅COO⁻ or CH₃COO⁻) had inhibitory effects on the removal of TP. The radical quenching experiments and electron spin resonance (ESR) spectroscopy results proved that hydroxyl radicals (·OH) played a key role in the oxidation of ATMP by Fenton method. In summary, the Fenton method could effectively oxidize ATMP to \mathrmPO_4^3- , and facilitate phosphorus recovery by forming ferric phosphate (FePO₄) precipitates via the combination of \mathrmPO_4^3- and Fe³⁺ under certain conditions. This study could provide reference for the resourceful treatment of industrial wastewater containing ATMP.