Batch ED fed by a PV unit: A reliable, flexible, and sustainable integration

Electrodialysis (ED) is a reliable technique to produce drinking water from brackish raw water sources. If the ED unit is fed by a photovoltaic (PV) generator, water production maybe also understood as sustainable. In this paper, the feasibility of a small and easily operating batch ED pilot plant powered by PV modules or by a rectifier (electrical grid connection) was studied in depth. First, a mathematical model was implemented in order to predict the batch ED-FV pilot plant behavior. Then, numerous tests were carried out at the experimental installation. Some relevant parameters were studied: the influence of NaCl concentration (600-10,000 ppm), the applied voltage (8-12 V), and the configuration of PV array, as well as environmental conditions. Different optimal operating conditions were investigated depending on the batch ED energy source: if the ED stack was fed by the rectifier, the lowest specific energy consumption or maximal production was followed. On the contrary, when it was fed by the PV array, the maximum power production of the PV modules was pursued. This maximum PV power depended on irradiation, ambient temperature, and solutions concentration, and consequently varied along any test.