Electrochemical oxidation of glyphosate coupled with induced crystallization for simultaneous phosphorus recovery

Non-reactive phosphates (NRPs) need to be transformed into orthophosphate (PO₄^3-, P) before they can be precipitated for recovery from water. This study provides a technology for simultaneous degradation and recovery of NRPs through electrochemical advanced oxidation (EAO) coupled with induced crystallization (IC). The EAO-IC process can achieve a degradation rate of 100% of 1 mM glyphosate (Gly), conversion rate of 98.1% of Gly to P, and efficient resource recovery of 79.1% of P to amorphous calcium phosphate (ACP) products with the reaction time of 5h. The use of a carbon felt (CF) wrapped Ti plate cathode provides a localized high pH environment and abundant nucleation sites for efficient recovery of P. Meanwhile, CF-Ti promotes the transfer of the precipitation region of ACP from the liquid phase to the solid phase. Compared with the Ti system, the phosphorus recovery rate and the Ca²⁺ precipitation rate increased by 5 times and 3.8 times in the CF/Ti system. And 98% of the precipitates was enriched on the CF surface, leading to reduced fouling on the cathode plate. The abundance of C-OH on the surface of CF is considered as the attachment site of ACP. Moreover, the effect of carbon felt on phosphorus recovery increased with the number of applications. This study presents a promising approach for NRP recovery from wastewater and facilitates low-energy resource utilization strategies for simultaneous benefits of 'pollution reduction and carbon reduction' and 'resource recovery' with one investment.