Exploring differential pressure-induced hydraulic flows in pilot-scale Electrodialysis with Bipolar Membranes

Electrodialysis with Bipolar Membranes (EDBM) is an electro-membrane process that produces acid and base from saline solutions using electricity. In previous research, this technology has predominantly been explored at the laboratory scale, with very few examples at the pilot scale. This study investigated, for the first time, how differential pressures applied between the EDBM channels affect its performance, utilizing a semi-industrial scale pilot - the largest ever studied in the literature. For this, inlet pressures from 0.5 to 1.5 barg were applied in the EDBM channels. Results were compared in terms of volume variation, product purities and key performance indicators, such as Current Efficiency (CE) and Specific Energy Consumption (SEC). Results indicate that changing the pressure between the channels induces a volumetric flow between compartments, which impacts the EDBM's performance. Specifically, the SEC ranged from 1.20 to 1.58 kWh kg_NaOH^-1, considering the energy required for both electricity and pumping at base concentration of ∼0.66 mol L^-1. Notably, SEC values were 24% lower than the reference case study when operating with the identified best set of pressures. Under similar conditions, the CE varied between 64 % and 86 %, depending on the pressure applied between the channels. Moreover, using this set of pressures, acid and base product purities remained above 90%. This study advances pilot-scale EDBM process intensification, highlighting its potential for reduced energy consumption, increased sustainability, and industrial competitiveness.