Transparent Exopolymer Particles: From Aquatic Environments and Engineered Systems to Membrane Biofouling

Abstract

Transparent exopolymer particles (TEP) are ubiquitous in marine and freshwater environments. For the past two decades, the distribution and ecological roles of these polysaccharide microgels in aquatic systems were extensively investigated. More recent studies have implicated TEP as an active agent in biofilm formation and membrane fouling. Since biofouling is one of the main hurdles for efficient operation of membrane-based technologies, there is a heightened interest in understanding the role of TEP in engineered water systems. In this review, we describe relevant TEP terminologies while critically discussing TEP biological origin, biochemical and physical characteristics, and occurrence and distributions in aquatic systems. Moreover, we examine the contribution of TEP to biofouling of various membrane technologies used in the desalination and water/wastewater treatment industry. Emphasis is given to the link between TEP physicochemical and biological properties and the underlying biofouling mechanisms. We highlight that thorough understanding of TEP dynamics in feedwater sources, pretreatment challenges, and biofouling mechanisms will lead to better management of fouling/biofouling in membrane technologies.

Characterisation of algal organic matter produced by bloom-forming marine and freshwater algae

“…Myklestad (1995) highlighted the significance of studying extracellular polysaccharides as they may comprise more than 80% of algal organic matter (AOM). In seawater, algal-derived acidic polysaccharides have been reported to be highly sticky and likely involved in the coagulation of colloidal/particulate materials in aquatic environments, which may result in the formation of mucilaginous aggregates such as marine snow and sea foam (Alldredge and Silver, 1988;Mopper et al, 1995). These sticky materials are often referred to as transparent exopolymer particles (TEP; see review by Passow, 2002).…”

Thin-film composite forward osmosis membranes functionalized with graphene oxide–silver nanocomposites for biofouling control

“…Furthermore, biofouling development can lead to 63 an increase in energy consumption [5][6][7]. Ordinary procedures such as pretreatment and 64 chemical cleaning are being used to mitigate biofouling [5,6].…”

Seawater reverse osmosis desalination and (harmful) algal blooms

“…Recently, Berman and co-workers proposed a "revised paradigm" of aquatic biofilm formation facilitated by TEPs emphasising the important role of TEPs in the conditioning and bacterial colonisation of surfaces (including reverse osmosis membranes) exposed to seawater (Berman and Holenberg, 2005;Bar-Zeev et al, 2012a;Berman et al, 2011;Bar-Zeev et al, 2015). The "revised paradigm" is illustrated and explained in detail in Figure 3.…”