Desalination of water with high conductivity using membrane-free electrodeionization

• MFEDI using two types of strong base resins has been tested for desalination of feed water with high conductivity.
• The effluent conductivity was 0.056–0.066 μS/cm only.
• Effective regeneration was obtained.
• The resins after repetitive use still remained their good performance in purification and regeneration.

Our previous work has shown that membrane-free electrodeionization (MFEDI) is a promising process for high purity water (HPW) production. However, this technique was only suitable to feed water with low conductivity, usually below 20 μs/cm. To extend the applicable range, type I strong base resin was used together with type II strong base resin in this work, due to the high capacity and easy regeneration of type II strong base resin and the excellent purification performance of type I strong base resin. It was demonstrated that although the conductivity of the feed water increased to 50 μS/cm, effective purification was still achieved, with effluent conductivity being 0.056–0.066 μS/cm only. The average conductivity of the concentrate collected during regeneration was over 380 μS/cm, indicating high regenerating efficiency. The water recovery reached 86% and the power consumption was 1.5 kW h/m3 water. In addition, repetitive experimental results showed that the MFEDI system could work stably.