Development of an alternative P fertilizer based on P recovery from wastewater using Fe-doped biochars

Phosphorus (P) is an essential macronutrient for plant growth, but its availability in agricultural soils is often limited due to strong fixation and leaching. Conventional phosphate fertilizers, derived from non-renewable phosphate rock, raise sustainability concerns due to resource depletion, inefficiency, and environmental risks like eutrophication. This study explores Fe-modified biochar (BC-Fe-P) as an alternative phosphorus fertilizer, enhancing phosphorus recovery from wastewater and providing a slow-release nutrient source for soils. Biochar, produced via biomass pyrolysis, was functionalized with goethite (α-FeOOH) to improve phosphate adsorption. The Fe-modified biochar was characterized using FTIR, SEM-EDS, XRD, and ICP analysis. Adsorption studies showed that phosphorus retention followed the Freundlich model, indicating a heterogeneous adsorption process with strong Fe-P interactions. Soil incubation experiments confirmed BC-Fe-P as a slow-release fertilizer, gradually supplying phosphorus while reducing leaching losses compared to conventional fertilizers. This dual-function material not only recovers phosphorus from wastewater but also enhances soil fertility, supporting circular economy solutions in nutrient management. Further research is needed to optimize biochar modification, assess long-term field performance, and evaluate its broader impact on soil health and crop productivity.