Boron removal in water using a hybrid membrane process of ion exchange resin and microfiltration without continuous resin addition

Abstract

Boron contained in seawater and some natural ground waters is harmful for plants and humans, especially water obtained by reverse osmosis desalination can contain a high level of boron. In this study, we investigated a hybrid process for boron removal from water which associates sorption on ion exchange resin in batch and microfiltration. In this approach, the ion exchange resin Amberlite IRA 743 was first ground to a mean particle size of 40–60μm to increase its kinetics. A ceramic microfiltration membrane was used to retain the ion exchange resin in the feed tank and the circulation loop while the model solution of boron was continuously added and the permeate collected for analysis. The effect of resin dosage, boron initial concentration, transmembrane pressure and membrane pore size was studied. A concentration below 0.3mg/L was obtained during a long time at sufficient resin dosage. The results were analyzed in terms of volume treated at breakthrough and permeate flux. In particular, it was shown that the transmembrane pressure and membrane pore size increased the permeate flux, but also decreased the volume treated at breakthrough, probably due to insufficient residence time. Moreover, the ion exchange resin and the microfiltration membrane were efficiently regenerated with HCl (0.37%) followed by NaOH (1%) and reused. Overall, it is suggested that the hybrid process of ion exchange resin in batch and microfiltration may be a possible technique for boron removal.