Boron removal from seawater using a hybrid sorption/microfiltration process without continuous addition of resin

Abstract

Desalinated water obtained by reverse osmosis may contain higher amount of boron than required by legislations. Therefore, the water obtained must follow additional treatments like sorption in ion exchange columns or double pass reverse osmosis. In this paper, we present results on boron removal from seawater using a hybrid ion exchange resin/microfiltration technique without continuous resin addition. First, fine resins were obtained by grounding and sieving at 40 and 60 μm commercial resins (Amberlite IRA743, Diaion CRB05 and Purolite S108). The resins were then tested in batch to obtain the kinetics and in the hybrid sorption/microfiltration technique to measure breakthrough curves and permeate flux of the microfiltration membrane. For the Amberlite IRA743 resin, the overall process was tested: reverse osmosis followed by hybrid sorption/microfiltration. At these experimental conditions (3.33 g/L resin, microfiltration membrane pore size 0.1 μm), removal of boron from seawater was almost complete as well as bacterial and phytoplankton cells. The hybrid process was able to reduce concentration of bacterial and phytoplankton cells thanks to steric rejection by the microfiltration membrane, suggesting that the same membrane can be used as a pretreatment before reverse osmosis in a complete desalination plant.