Fouling and its control in membrane distillation—A review

Abstract

Membrane distillation (MD) is an emerging thermally-driven technology that poses a lot of promise in desalination, and water and wastewater treatment. Developments in membrane design and the use of alternative energy sources have provided much improvement in the viability of MD for different applications. However, fouling of membranes is still one of the major issues that hounds the long-term stability performance of MD. Membrane fouling is the accumulation of unwanted materials on the surface or inside the pores of a membrane that results to a detrimental effect on the overall performance of MD. If not addressed appropriately, it could lead to membrane damage, early membrane replacement or even shutdown of operation. Similar with other membrane separation processes, fouling of MD is still an unresolved problem. Due to differences in membrane structure and design, and operational conditions, the fouling formation mechanism in MD may be different from those of pressure-driven membrane processes. In order to properly address the problem of fouling, there is a need to understand the fouling formation and mechanism happening specifically for MD. This review details the different foulants and fouling mechanisms in the MD process, their possible mitigation and control techniques, and characterization strategies that can be of help in understanding and minimizing the fouling problem.

Fouling in Membrane Distillation, Osmotic Distillation and Osmotic Membrane Distillation

“…More details on the properties needed for a membrane to be used in MD are summarized elsewhere [15,18,19,22,23]. Eykens, et al [23] gave a comprehensive overview of the optimal membrane properties, specifically for MD process.…”

“…It is worth noting that very few studies have been published so far on fouling mechanisms in MD, OD and OMD and investigations on the kinetics behind fouling phenomena and fouling mitigation remain very scarce [12,13]. Two review papers have been published on fouling and scaling in MD but not on OD and OMD [14,15]. Moreover, when fouling is studied, the considered characterization techniques focused only on the average physico-chemical properties of the surface deposits but not on the underlying deposit layers [12].…”

Fabrication of novel poly(m-phenylene isophthalamide) hollow fiber nanofiltration membrane for effective removal of trace amount perfluorooctane sulfonate from water

“…To investigate this phenomenon, the PFOS adsorption on the PMIA hollow fiber membrane was determined using a method similar to Ref. [60] Furthermore, atomic force microscopy (AFM) was also adopted to characterize the three-dimensional image and roughness of the surface of the virgin and fouled membrane [61][62][63][64][65]. Flux reduction as observed from Figs.…”

Ultrasonic irradiation control of silica fouling during membrane distillation process

“…Membrane scaling in MD process is of particular importance, as scaling can alter membrane surface properties, change membrane pore structure, potentially lead to the wetting of membrane pores and ultimately cause a decline in membrane permeability [11]. Scaling of sparingly soluble salts such as CaCO 3 , CaSO 4 , and silicates has been identified as a cause of flux decline when recovering water from natural streams, including brines from desalination processes [12][13][14][15].…”