Blast furnace sludge loaded with phosphate: a potential low-cost fertilizer

Given the potential shortage of phosphate rock reserves and its implications for food production, this study proposes a promising solution through the valorization of steel residues as a material for phosphate adsorption/desorption. The objective was to evaluate the potential of blast furnace sludge (BFS) for recovering phosphate as a fertilizer. Phytotoxicity assays confirmed the non-toxic and non-phytotoxic nature of BFS, ensuring its safety for agricultural use. Desorption experiments demonstrated that approximately 97% of the loaded phosphate could be efficiently released using a carbonate solution. Moreover, bioavailability assays revealed that BFS contains approximately 8% of macronutrients by weight, along with essential micronutrients. The phosphate adsorbed onto BFS was found to be readily available to the soil, making BFS a promising carrier of phosphate uptake by plants while preserving environmental well-being. These findings underscore the significance of BFS as an effective phosphate carrier that can be utilized without the need for pre-treatment. Furthermore, BFS offers the advantage of being a cost-free material that contributes to the valorization of steel industry waste in alignment with sustainable principles. This research demonstrates the potential of BFS in addressing phosphate shortage challenges in agriculture while promoting resource efficiency and sustainable practices.

Automated summary

This study proposes the use of steel residues as a material for phosphate adsorption/desorption, providing a promising solution to potential food production issues caused by phosphate rock shortage. The findings indicate that blast furnace sludge (BFS) is non-toxic, non-phytotoxic, and contains essential macronutrients and micronutrients. Desorption experiments show that a carbonate solution could efficiently release about 97% of loaded phosphate. Moreover, bioavailability assays demonstrate that the phosphate adsorbed onto BFS is readily available to the soil, making BFS a promising carrier for phosphate uptake by plants while preserving the environment. The significance of BFS lies in its effectiveness as a phosphate carrier without the need for pre-treatment, as well as its contribution to the valorization of steel industry waste in line with sustainable principles.