Phosphate removal from water using an iron oxide impregnated strong base anion exchange resin

Removing phosphate from water is important as it causes eutrophication, which in turn has a harmful effect on aquatic life, resulting in a reduction in biodiversity. On the other hand, recovery of phosphate from phosphorus containing wastewater is essential for developing an alternative source of phosphorus to overcome the global challenge of phosphorus scarcity. Phosphate removal from aqueous solutions was studied using an iron oxide impregnated strong base anion exchange resin, Purolite FerrIX A33E in batch and fixed-bed column experiments. Phosphate adsorption in the batch study satisfactorily fitted to the Langmuir isotherm with a maximum adsorption capacity of 48 mg P/g. In the column study, increase in inlet phosphate concentration (5–30 mg P/L), and filtration velocity (2.5–10 m/h) resulted in faster breakthrough times and increase in breakthrough adsorption capacities. Increase in bed height (3–19 cm) also increased adsorption capacity but the breakthrough time was slower. The breakthrough data were reasonably well described using the empirical models of Bohart–Adams, Thomas, and Yoon–Nelson, except for high bed heights. Phosphate adsorbed was effectively desorbed using 1 M NaOH and the adsorbent was regenerated after each of three adsorption/desorption cycles by maintaining the adsorption capacity at >90% of the original value. Greater than 99.5% of the desorbed P was recovered by precipitation using CaCl2.