Optimizing phosphorus recovery from an acidic pulp stream with cobalt ferrite nanoparticles: A methodology for pulp mills

Phosphate, a critical resource essential for agriculture and industry, faces a rising demand that outpaces population growth. The European Union's classification of phosphate as a critical raw material since 2011 highlights its significance and the region's dependence on imports. To address this challenge, our study aims to enhance phosphorus recovery from real industrial effluents utilizing cobalt ferrite nanoparticles. We employed the design of experiments along with response surface methodology to optimize the phosphorus recovery process and identify the most influential factors. The optimal conditions for achieving over 80% phosphorus recovery from a 25 mg P/L solution were found to be either a sorbent dose of 3.5 g/L with a 15-minute contact time or a 2.5 g/L dose with 1 hour if exposure, both at pH 6 and 60 ºC. Additionally, this study demonstrates that reusing nanoparticles in multiple 15-minute sorption cycles yielded higher phosphorus recovery compared to a continuous 1-hour cycle. This approach offers an effective and eco-friendly way to recover phosphorus from pulp mill effluents, reducing environmental impact and providing a valuable resource for the future, thereby contributing to the circular economy of phosphorus. • Addressed the EU's phosphorus supply issue by recovering it from alternative sources. • Phosphorus recovery using CoFe 2 O 4 colloidal nanoparticles achieves over 80% efficiency. • Sorbent dose, contact time, and pH are key factors in optimizing phosphorus recovery. • Reusing nanoparticles in 15-minute cycles enhances phosphorus recovery efficiency. • Revealed how pulp mills can lower environmental impact via efficient phosphorus recovery. • Optimized phosphorus recovery process through DoE and RSM by applying CCD.