In-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber membrane processes: A critical review

Abstract

Membrane fouling is the most serious challenge in the hollow fiber microfiltration (MF) and ultrafiltration (UF) processes. A number of in-situ monitoring techniques including optical and non-optical probes have been developed so that membrane fouling is better understood and controlled. This will help advance the membrane technology. In addition, the local filtration hydrodynamics wield a great influence on the membrane fouling formation and system operation stability. State-of-the-art in-situ monitoring techniques for membrane fouling and local filtration characteristics in hollow fiber MF/UF processes are critically reviewed. The principles and applications of these techniques are addressed in order to assess their strengths. This study demonstrated that the real-time observation techniques mainly focus on idealized laboratory apparatus and little on commercial membrane modules. Consequently, more attention should be paid to the development of simple and effective methods or integrated detecting technology so as to satisfy the real status of hollow fiber filtration processes and the optimization of membrane module. On the basis of this review, future analyses considering practical requirements are suggested as R&D priorities.

Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

“…A reduction of flux with filtration time during MF of whey proteins has been attributed to an increase of the deposit layer height alone [30]. Apart from that, some studies were performed to qualitatively and quantitatively elucidate the structure of the deposit [31][32][33][34][35][36]. However, a correlation between the chemical analysis of the deposit layer and in-situ measured layer has not been shown so far.…”

Periodic electrolysis technique for in situ fouling control and removal with low-pressure membrane filtration

“…Mechanisms including the plugging of membrane pores, concentration polarization and cake layer formation at the membrane surface contribute to fouling build up on or within the membrane. Fouling deposits increase the required transmembrane pressure and necessitate use of chemical cleaning agents, which reduce membrane lifetime and increase operating costs [3,[17][18][19][20][21][22][23][24][25][26]. Although the fouling term can be related to both reversible and irreversible foulant adsorption, irreversible is the most problematic as it produces a flux decline that cannot be totally recovered [8,[27][28][29][30][31].…”

“…Previous investigations have sought to remove HA from feed water, assuming that HA is the major foulant type [29]. Yuan et al [38] Applied electric force is a powerful means to decrease the membrane fouling caused by negatively charged organic pollutants, is an environmentally benign technique, with significant milestones achieved commercially and scientifically so far [26]. This method is sometimes known as electro-filtration [52].…”

Membrane Fouling in Anoxic-Oxic MBR System Operated at Low Dissolved Oxygen

“…Additionally, membrane cleaning is needed in submerged MBRs by air scouring, which consumes a significant amount of energy [6]. The energy demands for oxygen supply and for fouling prevention comprise from 50 % to over 70 % of the total energy used in the treatment plant, accounting for about one third of the overall operating costs [9]. So, energy saving achieved by operating MBR processes under low dissolved oxygen would be an interesting approach.…”