Demineralization of geothermal water reverse osmosis (RO) permeate by electrodeionization (EDI) with layered bed configuration

•Production of pure water from RO permeate of geothermal water by EDI•The layered bed configuration of EDI system•The effect of process parameters on product water quality•The effect of process parameters on system performance

In this study, demineralization of reverse osmosis (RO) permeate of geothermal water by electrodeionization (EDI) method was investigated. The layered bed configuration of EDI system consists of Purolite A 500 anion exchange and Purolite CT 175 cation exchange resins in the central compartment. Selemion AME anion exchange and Selemion CME cation exchange membranes were used to separate the central compartment from the electrode compartments. The effects of applied voltage, feed flow rate and the concentration of Na2SO4 solution in the electrode compartments on product water quality were investigated. According to the results obtained, the average conductivity of RO permeate decreased from 15.0 μS/cm to 2.9 μS/cm in the product water when the applied voltage was increased. It was possible to obtain a product water with an average conductivity of 1.0 μS/cm by the increase in the feed flow rate.