Lanthanum and Sludge Extracellular Polymeric Substances Coprecipitation-Modified Ceramic for Treating Low Phosphorus-Bearing Wastewater

Excessive phosphorus discharge from fertilizers and detergents has caused severe eutrophication in water bodies, necessitating the upgrading of efficient and cost-effective adsorbents for phosphorus removal. In this study, a novel lanthanum and extracellular polymeric substance (EPS) coprecipitation-modified ceramic (La-EPS-C-450) was developed to address the limitations of existing adsorbents. The ceramic filler served as a robust and scalable matrix for lanthanum loading, while EPS introduced functional groups and carbonate components that enhanced adsorption efficiency. The prepared adsorbent manifested a maximum phosphorus adsorption capacity of 83.5 mg P/g-La at 25 °C, with its performance well expressed by the Freundlich isotherm model, indicating that it was a multilayer adsorption process. The adsorption mechanism was driven by electrostatic attraction and ligand exchange between lanthanum and phosphate ions, forming inner-sphere complexes. The material demonstrated unfluctuating‌ performance across a pH range of 3–7 and retained high selectivity in the presence of competing anions. In practical applications, La-EPS-C-450 effectively removed phosphorus from actual river water, achieving a treatment capacity of 1800 bed volumes in a continuous-flow fixed column system. This work provides valuable insights into the progress of advanced ceramic-based adsorbents and demonstrates the potential of La-EPS-C-450 as a cost-efficient and effective material for phosphorus removal in water treatment applications.