Integrated Direct Contact Membrane Distillation – Reverse Electrodialysis for Water and Energy Production

Reverse Electrodialysis (RED) is an innovative technology able to “extract” electrochemical energy from salinity gradients [1]. In RED, cation/anion conductive membranes and spacers are properly assembled in an alternating way to separate diluate and concentrate compartments. When feeding the stack with low and high concentrated salt solutions, the concentration gradient between both compartments originates a Nernst potential across the cell pairs, and an electrical current flows through an external load connected to the electrodes. Membrane Distillation (MD) is an emerging technology able to concentrate saline solutions with very high recovery factor and under moderate temperature gradients established across a microporous hydrophobic membrane [2]. When applied to seawater, MD is able to generate a high concentrated brine to be used as a feed to RED stack; therefore, the simultaneous production of pure water and energy makes the integration of both operations very attractive for desalination industry also in terms of mitigation of brine disposal problems. In this work, 0.5 M NaCl solution is concentrated up to 6 M by Direct Contact Membrane Distillation (DCMD), and the produced brine is fed to RED stack. The performance of DCMD-RED is analyzed in terms of Open Circuit Voltage and power density. Bibliography [1] E. Brauns, Desalination 237 (2009) 378 [2] E. Curcio, E. Drioli. Sep. Pur. Review 34 (2005) 35