Electroprecipitation technology for nutrient recovery: Unlocking wastewater's potential

The reduction of surface water pollution, particularly eutrophication, can be achieved through the extraction and recovery of phosphorus (P) and nitrogen (N) from wastewater (WW). Their reuse supports sustainable agriculture, minimises the depletion of natural resources, and aligns with circular economy principles. In this study, electroprecipitation (EP) was applied to real WW samples collected from three WW treatment plants of different sizes (9000, 40,000, and 150,000 population equivalent (PE)). The influence of reaction time and current density on nutrient recovery was investigated in batch experiments using magnesium anodes, at 22 °C with continuous stirring and a fixed electrode spacing (1 cm), without adjusting pH or electrical conductivity. After EP, the treated effluents were filtered. The liquid phase was analysed for physicochemical parameters, SS, N, P, COD, BOD, metals and Escherichia coli, while the precipitate was characterized using FTIR and XRD, pseudo-total metal content, PAHs, and microbiological safety indicators. The results demonstrate that each WW matrix requires tailored treatment conditions: optimal recovery was achieved at 30 min/20 A·m 2 for WW1, 30 min/10 A·m 2 for WW2, and 90 min/20 A·m 2 for WW3. Under these conditions, P removal exceeded 90 %, while N removal ranged from 20 % to 30 %. The resulting precipitates met both EU and Serbian regulations for metal content, confirming their suitability as fertilisers. Treated effluents also complied with EU Regulation 2020/741 for agricultural reuse, with WW2 and WW3 showing broader applicability than WW1. These findings support the potential for implementing electrochemical nutrient recovery at full scale, contributing to circular and sustainable WW management. • Mg-electrodes are highly efficient and powerful tool for struvite precipitation. • The reaction time and current influence on the EP process was analysed. • Optimal conditions for phosphorus recovery varied depending on the WWTP. • EP is a sustainable solution for nutrient recovery from wastewater effluent.