Investigation of membrane fouling mechanisms using blocking models in the case of shear-enhanced ultrafiltration

Abstract

Shear-enhanced ultrafiltration is considered as an important membrane technology that can contribute to pre-treat dairy wastewater and recycle valuable components such as milk proteins. However, to be efficient, it necessitates the establishment of proper methods for the assessment of membrane fouling. Four membrane blocking models proposed by Hermia were used to quantify and assess the membrane fouling of shear-enhanced filtration observed in dairy wastewater treatment. The experiments were performed with various shear rates, mean transmembrane pressure (TMP), temperature and membrane types. Good agreement between complete pore blocking model and experimental data was found, confirming the validity of the Hermia models for assessing the membrane fouling of shear-enhanced filtration system and that only some “sealing” of membrane pores occurs which is due to the high speed shearing effect. Furthermore, the increments of shear rate, TMP, and temperature can decrease the degree of “sealing” of membrane pores and improve filtration performance. In addition, a three-step membrane cleaning mode has achieved very satisfying results in subsequent membrane cleaning. This work confirms that, unlike traditional filtration mode (dead-end and cross flow filtration), high shear dynamic filtration possesses a low degree of membrane fouling and a higher membrane permeability recovery after cleaning.