Patent ID: 7807032

Claim:
A process for the separation and recovery of boron from an aqueous solution of nuclear power plant wastewater containing non-dissociated boric acid, using a five-compartment electrochemical cell comprising a first and second diluting compartment, a first and second anolyte compartment, one catholyte compartment, and one anode and two cathodes, whereby a first cation-exchange membrane separates the catholyte compartment from the first diluting compartment, a first anion-exchange membrane separates the first diluting compartment from the first anolyte compartment, a second anion-exchange membrane separates the second anolyte compartment from the second diluting compartment, a second cation-exchange membrane separates the second diluting compartment from the catholyte compartment, and an anode separates the first and second anolyte compartments, the anode being provided with a hole for the flow of anolyte between said first and second anolyte compartments, the method comprising: feeding untreated aqueous solution to the first diluting compartment for separating strongly dissociated anions by electrical migration performed in the first diluting compartment, wherein the first diluting compartment is filled with cation-exchange material only, and separating dissociated cations by ion-exchange/electrical migration in said first diluting compartment; feeding the aqueous solution treated in the first diluting compartment to the second diluting compartment for separating boron by electrochemical/chemical dissociation, ion-exchange/adsorption, and electrical migration performed in said second diluting compartment, wherein said second diluting compartment is filled with anion-exchange material or a mixture of anion- and cation-exchange materials, or layers of anion- and cation-exchange materials separated from each other; recovering the separated cations into the catholyte compartment of the electrochemical cell; recovering the separated boron into at least one of the anolyte compartments of the electrochemical cell; recirculating the anolyte in said at least one anolyte compartment recirculating the catholyte in said catholyte compartment; and recirculating the diluted solution in said first and second diluting compartments if necessary.