Effect of direct electric current and field on biofouling in ED and RED

Abstract

Electrodialysis -ED- and revers electrodialysis -RED- are electrochemical membrane processes with ion exchange membranes used to produce potable water and sustainable clean energy, respectively. The characteristic of these process is that the direct electric current flows through the system. It is known that, in these systems, anion exchange membranes -AEMs- are most likely affected by fouling. Then, in this study, we attempted to evaluate the effect of direct electric current and field on biofouling behaviour of AEM under ED and RED operation.<br><br>In this work, Neosepta AMX -Astom Corp., Tokyo, Japan- was used as AEM and P. putida as a model bacteria. ED was carried out under a constant current density -2mA/cm2- with bacterial suspension -O.D.450: 0.5- containing 0.05 M NaCl as a feed solution. For RED, the bacterial suspension -O.D.450: 0.5- containing 0.507 M NaCl and pure 0.05 M NaCl solution were used as high salinity water and low salinity water, respectively. The immersion test was also carried out with high salinity water for RED to evaluate the effect of electric current and field. Each experiment was done for 20 h. <br><br>The biofouling behaviour was evaluated by observing fouled membrane surfaces with a scanning electron microscope -SEM- as shown in Fig. 1. The coverage percentage was obtained by analyzing the SEM images. From Fig.1, it was found that the direct electric current and field decreases the bacteria attachment. In addition, the electric current changed the bacterial shape, leading to a decrease in bacterial attachment. Higher current density used in ED was more effective for reducing the bacterial coverage.