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Voltage spike and electroconvective vortices generation during electrodialysis under pulsed electric field: Impact on demineralization process efficiency and energy consumption

Lemay, Noémie, Mikhaylin, Sergey, Bazinet, Laurent
Innovative food science & emerging technologies 2019 v.52 pp. 221-231
cheese industry, cleaning, cleaning agents, electric potential difference, electrodialysis, energy efficiency, fouling, mass transfer, pH, pulsed electric fields, sustainable development, whey
Electrodialysis (ED) with pulsed electric field (PEF) has never been tested on complex food system such as sweet whey. In this study, seven PEF pulse-pause combinations were compared with DC current to assess their impacts on whey demineralization. High-frequency PEF improved the demineralization rate by 81% while reducing the energy consumption by about 16%. This was explained by the emergence of electroconvective vortices (ECV) at the beginning of each pulse due to the appearance of a voltage spike. Since their lifetime are around 0.5 s, these ECV did not have time to fade off during the whole process in the case of high-frequency PEFs increasing consequently the mass transfer. Furthermore, PEF ratio of 1 decreased pH changes and thus could prevent scaling and organic fouling formation. Hence, ED with PEF is a new advantageous energy-efficient approach for the demineralization of whey that could be used in the dairy industries.This study highlights the beneficial effects of using pulsed electric field (PEF) during ED in comparison to the DC current condition currently used everywhere in industry. First, for the same demineralization rate of sweet whey, PEF requires 16% less energy. This could allow the industries to better deal with the regulatory issues arising from the sustainable development goals. In addition, the use of PEF also prevents the fouling and scaling formation on the membrane, and thus could decrease the load of cleaning agent and the cleaning time required per amount of processed whey. High-frequency PEF such as 0.1 s-0.1 s is a promising greener alternative to conventional ED for demineralization of the million tons of whey generated by the cheese industry every year.