Understanding membrane fouling: a review of over a decade of research

Since the first membrane applications at the end of the 1980s, the water treatment engineering community has been able to develop reliable low pressure membrane systems that are capable of producing high quality drinking water at a competitive price, making membrane technology an attractive solution to both upgrade existing plants and design new ones. A competitive price means low capital and operating cost, which are inversely proportional to membrane hydraulic performance (permeate flux). Porous membranes lose their hydraulic performance as materials accumulate on their surfaces and/or within their pores, a process called membrane fouling. Although a significant effort has been devoted to elucidating the fouling mechanisms of polymeric membranes by natural organic matter (NOM), no single model has yet been accepted. In fact, most of the existing literature is contradictory, showing that membrane fouling is far from being fully understood. This article reviews over a decade of Ondeo's experience on characterizing and preventing fouling of polymeric membranes by natural organic matter and inorganic compounds. The review focuses on the role of NOM size and hydrophobicity, of membrane chemistry, and of solution pretreatment (coagulation and/or adsorption). In addition, the efficacy of some currently used strategies to minimize membrane fouling is also discussed.