Continuous production of high‐purity water by electro‐deionisation

Operating conditions were investigated for a packed-bed membrane cell for electro-deionisation of brackish or tap water to give high-purity water with electrical conductivity of the order 0.1 μmho/cm. Flow rates of 10–40 h−1, current densities of 0.5–5 mA/cm2, and incoming solution concentrations of up to 0.01 N were used. It was shown that strongly acidic cation-exchange resin plus strongly basic anionexchange resin in volume ratio 1:1 was the most effective, and that particle size needed to be 60–80 mesh and resin bed thickness 3 mm for optimum current efficiency in purifying water to the required standard.