Validation of pilot-scale phosphate polishing removal from surface water by lanthanum-based polymeric nanocomposite

Pilot-scale study is a critical step towards practical application. In this work, a pilot-scale adsorption system was established to validate and to evaluate the performance of phosphorus (P) polishing removal using the lanthanum-based polymeric nanocomposite La@201, with an average treatment capacity of 10 m(3)/day over a period of 8 months. The adsorption system effectively reduced the P concentration to below the eutrophic limit (0.02 mg/L), achieving an average removal efficiency of 91.23% for orthophosphate and 78.51% for total phosphorus. The adsorption system exhibited high stability, robustness, and resilience towards external stimuli such as the fluctuating influent P concentration, varying turbidity, and competing ions. The limited dissolution of La from the La@201 adsorbent was caused by the accumulation of organic matter in the two adsorption columns, indicating the material's high stability. In general, the river water complex matrix collectively affected the P removal efficiency by La@201 through synergistic effects in which the turbidity, conductivity, and fluoride ions contributed the most. Post characterization of adsorbents after the operation identified multiple La-P phases, which are drastically different from the observation in lab-scale experiments, however still indicating the dominating role of the La-P interaction for selective P removal. The regeneration process was used to transform the used La@201 to its pristine state reversely. We believe this study indicates the excellent potential of La@201 for practical applications, offers new insights into the design and scaling-up of novel adsorbents and adsorption technology for polishing phosphate treatment from natural waters and wastewater.