Electroosmotic Flow Stimulates the Release of Alginate-Bound Phenanthrene

Abstract

There is growing interest in employing electro-bioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Most present applications of electrokinetics aim at pollutant extraction, which requires transport over large distances facilitated by electroosmotic flow (EOF). They do not explicitly account for the possibility that EOF passing along soil particles stimulates the release of hydrophobic organic compounds (HOC) and locally improves pollutant bioavailability. Here, we report on the stimulated release of polycyclic aromatic hydrocarbon (phenanthrene) from model organic matter in the presence of direct current (DC)-electric fields (0.5-2 V cm(-1)) typically used in electrobioremediation measures. Alginate beads were employed as a model polymer release system (MPRS) exhibiting similar release behavior as natural organic matter (NOM). In the presence of EOF the phenanthrene release flux from alginate beads was between 1.4- and 1.8-fold higher than under hydraulic flow conditions with equal bulk water velocity and 30-120-fold higherthan under stagnantwater conditions. Our data suggest that DC-electric fields (0.5-2 V cm(-1)) can stimulate the release of PAH bound to particles exposed to stagnant water zones often found at hydraulic flow regimes restricted by low permeability.