Fixed-bed column study of phosphate adsorption using immobilized phosphate-binding protein

• Published in: Chemosphere (Oxford) 2022-05, Vol.295, p.133908-133908, Article 133908
• Main Authors: Hussein, Faten B., Mayer, Brooke K.
• Format: Article
• Language: English
• Subjects: Adsorption; Breakthrough curve; Nutrient; PBP; Phosphate-Binding Proteins; Phosphates; Recovery; Removal; Thomas model; Waste Water; Water Pollutants, Chemical - analysis; Water Purification - methods
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2022.133908

Bio-adsorption using high-affinity phosphate-binding proteins (PBP) has demonstrated effective phosphorus removal and recovery in batch-scale tests. Subsequent optimization of design and performance of fixed-bed column systems is essential for scaling up and implementation. Here, continuous-flow fixed-bed column tests were used to investigate the adsorption of inorganic phosphate (orthophosphate, Pi) using phosphate-binding proteins immobilized on resin (PBP–NHS) targeting Pi removal to ultra-low levels followed by recovery. Time to breakthrough decreased with higher influent Pi concentration, smaller bed volume, and higher influent flow rates. The Thomas and Yoon-Nelson breakthrough models adequately described PBP-NHS resin performance with a correlation coefficient of R2 > 0.95. The sharp S-shape of the breakthrough curves for both Pi-only solution and multi-ion solution indicated highly favorable and selective separation of Pi using PBP-NHS resin, beyond that achieved using LayneRT™, a commercial ion exchange resin. The Pi adsorption capacity of the PBP-NHS column was unaffected by competing anions, whereas capacity of the LayneRT™ column dropped by 20%. Tertiary wastewater effluent was also successfully treated in PBP-NHS column tests with a typical S-shaped breakthrough curve. Operating the fixed-bed column in multi-cycle mode evidenced the reusability of PBP-NHS resin with no significant decline in column performance. The results of this study contribute to efforts to scale up designs of PBP-NHS adsorption systems. [Display omitted] •PBP-NHS resin provided high Pi selectivity compared to LayneRT™ ion exchange resin.•PBP-NHS resin's Pi adsorption capacity was not affected by wastewater constituents.•PBP-NHS resin offered consistent adsorption/desorption over three column cycles.•Thomas and Yoon-Nelson models had R2 > 0.95 for the column breakthrough data.