A Study on Biofouling and Cleaning of Anion Exchange Membranes for Reverse Electrodialysis

Abstract

This study covers the modification, (bio)fouling characterization, use, and cleaning of commercial heterogeneous anion exchange membranes (AEMs) to evaluate their feasibility for reverse electrodialysis (RED) applications. A surface modification with poly (acrylic) acid resulted in an improved monovalent perm-selectivity (decreased sulfate membrane transport rate). Moreover, we evaluated the (bio)fouling potential of the membrane using sodium dodecyl sulfate (SDS), sodium dodecyl benzenesulfonate (SDBS), and Aeromonas hydrophila as model organic foulants and a biofoulant, respectively. A detailed characterization of the AEMs (water contact angle, ion exchange capacity (IEC), scanning electron microscopy (SEM), cyclic voltammetry (CV), and Fourier Transform Infrared (FTIR) spectra) was carried out, verifying that the presence of such foulants reduces IEC and the maximum current obtained by CV. However, only SDS and SDBS affected the contact angle values. Cleaning of the biofouled membranes using a sodium hypochlorite aqueous solution allows for (partially) recovering their initial properties. Furthermore, this work includes a fouling characterization using real surface and sea water matrixes, confirming the presence of several types of fouling microorganisms in natural streams. A lower adhesion of microorganisms (measured in terms of total bacteria counts) was observed for the modified membranes compared to the unmodified ones. Finally, we propose a cleaning strategy to mitigate biofouling in AEMs that could be easily applied in RED systems for an enhanced long-term process performance.

Stability of Ion Exchange Membranes in Electrodialysis

“…There are several variants for classifying the types of fouling depending on the causing agents, for example, Mikhaylin and Bazinet [ 28 ] distinguish ( Figure 2 ) fouling with inorganic substances (which is denoted as scaling in some other articles), fouling with organic molecules and colloids (colloidal fouling of anion exchange membranes is discussed in a large number of publications, for example, in [ 29 , 30 , 31 ]; an example of the formation of peptide layers on a cation exchange membrane is described in [ 32 ]; peptide fouling of bipolar membranes is described in [ 33 ]) and biofouling, which, however, is more actively discussed in the context of reverse electrodialysis [ 34 , 35 ].…”

Fouling and Mitigation Behavior of Foulants on Ion Exchange Membranes with Surface Property in Reverse Electrodialysis

“…Fouling is one of the most common problems in electrodialysis (ED) using ion exchange membranes (IEMs). In general, fouling is caused by the precipitation of foulants such as organics, colloids and biomass into IEMs and/or onto the surface of IEMs [ 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The fouling causes a decrease in the transport flux of ions due to fouling complications of the membrane, an increase in the membrane resistance and a loss in selectivity and thus affects negatively membrane properties and performance [ 15 , 16 ].…”

Anion Exchange Membrane Based on BPPO/PECH with Net Structure for Acid Recovery via Diffusion Dialysis

“…would help further improve the acid recovery efficiency of the DD process and reduce energy consumption [7]. Many kinds of materials are used to manufacture anion exchange membranes, such as polysulfone (PSF) [15], polyvinyl alcohol (PVA) [16], chitosan (CS) [17], polybenzimidazole (PBI) [18], brominated poly (2,6-dimethyl-1,4-phenyleneoxide) (BPPO) [19] and other materials [20][21][22]. The anion exchange membrane consists of appropriate polymer materials, which can achieve good separation effects in acid recovery using DD.…”