Optimisation des performances du procédé d'électrodialyse et réduction du colmatage membranaire minéral par l’application de champs électriques pulsés dans le cadre de la déminéralisation et du retrait de l’acide lactique du lactosérum acide
|Advisor:||Bazinet, Laurent; Gaaloul, Sami; Mikhaylin, Sergey|
|Abstract:||Since several years, the increasing production of Greek-style yogurt, caseins and fresh cheese results in the co-production of increasing amounts of acid whey. If this co-product has nutritional qualities and even well-known pharmaceutical applications of some of its components, its use is hindered by drying issues. Indeed, acid whey high lactic acid and calcium contents are responsible for the powder hygroscopic character causing its agglutination during conventional spray-drying. Industrially, this whey is therefore treated by a series of processes such as nanofiltration, ion exchange resins and electrodialysis (ED) before hand in order to remove the problematic elements. However, this treatment represents a high investment and operating cost, in addition to generating large amounts of polluting effluents. The use of a single ED process would reduce these economical and ecological costs. However, the application of ED is limited by membrane fouling issues decreasing the process performance while increasing membrane’s cleaning and degradation, thus rendering an industrial application unsustainable. During this work, acid whey ED was performed using different membrane configurations and types of membranes. For the first time on acid whey, a configuration using bipolar membranes was tested. These first tests made it possible to measure the feasibility of an ED process for acid whey treatment in terms of demineralization and lactic acid removal. For several configurations, including the one using bipolar membranes, demineralization rate of 70% and lactic acid removal rate of 45% were achieved, allowing proper potential drying of the whey. However, a strong membrane scaling was observed. The scaling was identified and characterized for two different ED configurations in order to study the mechanisms involved in its formation throughout the process. Following these initial results, new tests were conducted aiming for the mitigation of the membrane scaling by means of pulsed electric fields (PEF). The present study demonstrated that the use of an adequate combination of pulse time and pause time can significantly reduce membrane scaling during acid whey treatment by ED, in addition to enhancing separation performance. This thesis also brings new elements of understanding regarding the mechanisms involved in the improvements brought by the use of the CEP through the test of nine different conditions. Among these mechanisms, a phenomenon of selective migration of divalent cations has been demonstrated and may be the subject of further studies aiming for the widening of ED process applications. Finally, the optimization of the CEP conditions made it possible to select electrodialytic parameters allowing the treatment of acid whey by ED while minimizing membrane scaling|
|Document Type:||Thèse de doctorat|
|Open Access Date:||30 September 2019|
|Collection:||Thèses et mémoires|
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