A power free electrodialysis (PFED) for desalination

A power free electrodialysis (PFED) is proposed for water desalination by integrating with a reverse electrodialysis (RED) as an energy donor. The effects of flow rates, salt concentration ratio between high salt concentration compartment (HC) and low salt concentration compartment (LC) on energy generation are investigated. The combination of ED and RED for fresh water production is attempted and the desalination performances in both continuous and batch-wise modes are investigated. The results show that the integration is feasible and the conductivity of the product water can be as low as 72μS/cm, which is indubitably qualified for drinking. To test the robustness of this hybrid technology, the batch-wise mode is chosen to generate power from simulated seawater and wastewater. It is found that the PFED can be successfully carried with no significant desalination difference compared to NaCl solution. PFED is thus confirmed to be technically feasible, and economically attractive for water desalination without the consumption of external energy. [Display omitted] •A power free electrodialysis (PFED) for water desalination was explored.•The PFED can achieve a synergistic enhancement effect on water desalination.•The PFED realize zero discharge of high salt wastewater.•The conductivity of fresh water can be as low as 72μScm−1.