Cost-Effective Magnetic LDHs for Simultaneous Sludge Dewatering and Phosphorus Recovery: A Scalable Approach for Municipal Wastewater Plants.

Phosphorus recovery from municipal sludge is essential to reduce environmental pollution and address the global phosphorus crisis. This study introduces a magnetic Fe/Mg/Zn-layered double hydroxide (LDH) composite for simultaneous phosphorus recovery and sludge dewatering from municipal wastewater. The synthesized composite exhibits a high phosphorus adsorption capacity of 25.79 mg/g, a reduction in sludge-specific resistance by 77.43%, and a 24.95% decrease in moisture content. The phosphorus adsorption process follows a pseudo-second-order kinetic model and Langmuir isotherm, and chemisorption mainly drives phosphorus adsorption. The characterization results showed that precipitation, complexation, and ligand exchange were the main adsorption mechanisms of phosphorus. The material maintains excellent performance across a wide pH range (3-11), with over 90% phosphorus removal efficiency after 5 cycles of adsorption-desorption. These results demonstrate the material's potential for sustainable and cost-effective phosphorus recovery and sludge management in wastewater treatment plants.