Challenges facing field applications of electrokinetic bioremediation: A critical review

Ikrema Hassan, Ernest K. Yanful, Eltayeb Mohamedelhassan

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geoenvironmental Engineering

ABSTRACT: Many remediation methods have been developed and utilized over the years for cleaning up contaminated sites. Among these methods bioremediation stands out for its low cost and efficiency. A main challenge facing the implementation of conventional bioremediation techniques is the difficulty to precisely and effectively deliver nutrients to indigenous bacteria, particularly in soils with tortuous paths and low hydraulic permeability. In the last decade, the implementation of bioremediation coupled with electrokinetics has been suggested to enhance the outcome of bioremediation. This hybrid remediation approach has the potential to restore contaminated sites with low hydraulic permeability where conventional bioremediation techniques are deemed ineffective. Nevertheless, the development of an acidic medium near the anode and alkaline environment in the vicinity of the cathode by electrolysis reactions creates unfavourable condition for bacteria. Controlling the pH gradient in electrokinetic applications is recognized by researchers and engineer as a major challenge facing this technique. RÉSUMÉ De nombreuses méthodes d'assainissement ont été développés et utilisés au fil des ans pour nettoyer les sites contaminés. Parmi ces méthodes bioremédiation se distingue par son faible coût et de l'efficacité. Un défi majeur face à la mise en œuvre de techniques de bioremédiation classiques est la difficulté à livrer précisément et efficacement les éléments nutritifs pour les bactéries indigènes, en particulier dans les sols avec des chemins tortueux et une faible perméabilité hydraulique. Dans la dernière décennie, la mise en œuvre de la bioremédiation couplé avec électrocinétique a été suggéré d'améliorer les résultats de la bioremédiation. Cette approche hybride de l'assainissement a le potentiel de restaurer les sites contaminés à faible perméabilité hydraulique où les techniques de bioremédiation classiques sont réputés inefficaces. Néanmoins, le développement d'un milieu acide à proximité de l'anode et de l'environnement alcalin dans le voisinage de la cathode par des réactions d'électrolyse crée condition défavorable pour les bactéries. Contrôle du gradient de pH dans les applications électrocinétiques est reconnu par les chercheurs et les ingénieurs comme un défi majeur pour cette technique. 1 INTRODUCTION Over the years, many remediation methods have been used with various degrees of success to mitigate soil pollution. Due to soil heterogeneity and the diverse contaminant types, the scientific community believes that there will not be a single universal remediation method for all types of soils and pollutants, instead effective remediation may include implementation of two or more methods (Virkutyte et al., 2002). Bioremediation is one of the most cost-effective remediation methods. There is a variety of bioremediation techniques including Biopile, Landfarming, Phytoremediation, Bioslurry, and Bioventing, that can be used to remove pollutants from contaminated sites. From a biological and chemistry point of view, bioremediation is defined as the employment of indigenous bacteria in a contaminated site to degrade the pollutions (indigenous bacteria use the pollutants as a food). The type of soil in a contaminated site usually plays a dominant role in the effectiveness of this technique. The main challenge facing the implementation of conventional bioremediation techniques is the difficulty in effectively and precisely delivering nutrients to indigenous bacteria, particularly in soils with low hydraulic permeability. Electrokinetic remediation is an emerging technology that has a tremendous potential for cleaning contaminated soils including fine-grained soils which are difficult to cleanup using conventional methods (Yeung et al., 1997). Some recent research studies have investigated the use of electrokinetics to improve the outcome of bioremediation. This hybrid approach has the potential to restore sites with low hydraulic permeability where conventional bioremediation techniques are deemed ineffective (Yeung et al., 1997). The transport phenomenon associated with electrokinetic remediation, namely, electroosmosic flow, electromigration, and electrophoresis, can be utilized to effectively deliver nutrients to indigenous bacteria in the soils. Nevertheless, the development of an acidic medium near the anode and an alkaline environment in the vicinity of the cathode by electrolysis reactions can, create unfavorable condition for bacteria (Alshawabkeh, 2009; Luo et al., 2005; Nyer and Suarez, 2002). There is also a concern regarding the availability of a power source especially in remote areas with insufficient or non-existing power lines. This paper discusses the major challenges facing field applications of

RÉSUMÉ: llenges facing field applications of electrokinetic bioremediation: A critical review Ikrema Hassan1, Ernest K. Yanful1 and Eltayeb Mohamedelhassan2 1Dept. of Civil Engineering Œ Western University, London, ON, Canada 2Dept. of Civil Engineering Œ Lakehead University, Thunder Bay, ON, Canada ABSTRACT

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Cite this article:
Ikrema Hassan; Ernest K. Yanful; Eltayeb Mohamedelhassan (2014) Challenges facing field applications of electrokinetic bioremediation: A critical review in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper309,author = Ikrema Hassan; Ernest K. Yanful; Eltayeb Mohamedelhassan,title = Challenges facing field applications of electrokinetic bioremediation: A critical review ,year = 2014}