Vibratory membrane bioreactor systems in wastewater treatment: A short review

Membrane bioreactor (MBR) technology is a promising method for advanced wastewater treatment due to its high-quality effluent. Intensive activated sludge used in the submerged MBR systems resulted in one of the biggest problems of these systems: fouling. Researchers tried to overcome the fouling problem by using vibratory processes in MBRs. Different types of oscillation systems with the control of frequency and amplitude have been investigated by various researchers with the implementation of short- and long-term analysis. Because of the challenges originated from the mixed liquor characteristics, short-term bench-tests may not be sufficient to give a holistic view of the vibratory motion in an MBR with an oscillation system. Understanding these studies with a comparative point of view is needed to present the efficiency of vibratory MBR systems, referring to their possibilities in full-scale applications. In this regard, the significance of this review was gathering current efforts in fouling control by the vibratory motion, especially as concerns in the submerged activated sludge membrane bioreactors. Vibratory MBR systems included in this review are classified into four categories according to the type of vibration employed: Longitudinal, transverse, rotational, and random. Under the theoretical background, the operational conditions and experimental results for each category are compared and deeply discussed.