Enhanced Schemes for Brine Valorization via Electrodialysis with Bipolar Membranes Powered by Renewable Energy

Abstract

Powering water treatment technologies with renewable energies by using the process buffering capacity as a way to indirectly store energy has been recently proposed as an effective strategy for the smart use of energy. With this respect, the production of chemicals from waste brines via electrodialysis with bipolar membranes (EDBM) can be particularly suitable due to its high energy intensity along with the extreme flexibility of the process. This study demonstrates, through real-environment experiments at the pilot scale, the feasibility of coupling an EDBM pilot plant with renewable energies (solar). The pilot plant was tested in a continuous process configuration (feed and bleed mode) under two different irradiation scenarios, i.e., summer and winter. The use of the controllers implemented allowed us to maintain the target concentration for acid and base fixed at 0.5 mol L-1 in both scenarios. In the summer scenario, current efficiency (CE) values higher than 90% and specific energy consumption (SEC) values lower than 2 kWh kg-1 were obtained, still maintaining a specific productivity (SP) of about 0.2 kg h-1 m-2. In the winter scenario, a current efficiency >80% was obtained, while SEC and SP values up to 1.6 kWh kg-1 and 0.06 kg h-1 m-2 were found, respectively. Results suggest that EDBM technology is perfectly suitable for the valorization of waste brines by using green energy sources, thus paving the way for its development at an industrial scale.