Sustainable Sorbent Materials for Phosphorus Removal and Recovery from Wastewater: A Comprehensive Review and TRL-Based Evaluation

The removal and recovery of phosphorus (P) from wastewater is critical for preventing eutrophication and achieving sustainable nutrient management. This review critically evaluates sustainable sorbent materials for P removal and recovery, focusing on mineral-based, bio-based, and recycled sorbents derived from industrial by-products. It compares their P removal efficiencies, adsorption mechanisms, environmental impact, and regeneration potential. A structured application of the Technology Readiness Level (TRL) framework is used to evaluate the maturity, scale-up feasibility, and real‑world implementation potential of the reviewed P sorbents. The TRL‑based assessment complements performance comparisons by explicitly considering cost‑effectiveness, regulatory and policy alignment, and compatibility with existing wastewater treatment infrastructure. Sustainability aspects are addressed through lifecycle‑relevant criteria, including regenerability and reuse potential and valorisation pathways for spent sorbents (e.g., reuse as soil amendments or slow‑release fertilisers). The review concludes by identifying key evidence gaps (notably long‑term validation in real wastewater and robust regeneration/P‑recycling routes) and outlining research priorities to accelerate the development of efficient, scalable, and environmentally viable solutions for phosphorus recovery in wastewater treatment.