Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay

Abstract

Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK–enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective forestablis hingmicrobial reductive dechlorination capacity in low-permeability soils.

Groundwater Remediation in Low‐Permeability Settings: The Evolving Spectrum of Proven and Potential

“…Although EK approaches have been applied for decades to enhance contaminant migration, recent work shows the technology offers new promise if applied to deliver remediation reagents into low‐permeability zones and increase overall reagent distribution uniformity in geologically heterogeneous settings. A number of recent laboratory studies have demonstrated the potential for EK techniques to enhance the delivery of permanganate (Reynolds et al ), lactate and bacteria (Mao et al ), and surfactants (e.g., Hahladakis et al ). More specifically, in laboratory experiments, Mao et al () were able to distribute Dehalococcoides and lactate ions at transport rates of approximately 3.2 cm/day across a bentonite clay, resulting in the complete dechlorination of PCE.…”

“…A number of recent laboratory studies have demonstrated the potential for EK techniques to enhance the delivery of permanganate (Reynolds et al ), lactate and bacteria (Mao et al ), and surfactants (e.g., Hahladakis et al ). More specifically, in laboratory experiments, Mao et al () were able to distribute Dehalococcoides and lactate ions at transport rates of approximately 3.2 cm/day across a bentonite clay, resulting in the complete dechlorination of PCE. These results are comparable to the electromigration rate of bromide (3.3 cm/day) measured in column studies using low‐permeability site soils by Cox et al ().…”

[Preprint] An overview of electrokinetic soil flushing and its effect on bioremediation of hydrocarbon contaminated soil

“…If the environmental conditions do not support microorganisms growth, electrokinetic can transmit a number of nutrients, electron acceptors, complexing agents, and also surfactant to microorganisms so biodegradation limitation in soil can be reduced (Annamalai et al, 2017;Da Rocha et al, 2009;Guo et al, 2014;Li et al, 2012b;Luo et al, 2006;Mena et al, 2016c). Several researches also suggest that microorganisms can be flushed into soil to improve removal efficiency because indigenous microorganisms can not treat hydrocarbon contaminants effectively (Asgari et al, 2013;Kim et al, 2005;Mao et al, 2012).…”

A Review Article: Electrokinetic Bioremediation Current Knowledge and New Prospects

“…Recent study showed that microorganisms can be transported by electrokinetics in sand via electrophoresis and the microorganisms remained active and viable after the transport process [42]. Another study showed that by adding bacteria in the anode and cathode compartment bacteria was transported via electroosmotic flow in clay soil [43]. However, in general, bioaugmentation studies have not been successful.…”