Optimal Field Approaches for Electrokinetic In Situ Oxidation Remediation

Abstract

Numerical simulations were used to identify and evaluate optimum electrode configurations and approaches for electrokinetic in situ chemical oxidation (EK‐ISCO) remediation of low‐permeability sediments. A newly developed groundwater and EK flow and reactive transport numerical model was used to conduct two‐dimensional scenario simulations of the coverage of an injected oxidant, permanganate, and the oxidation of a typical organic contaminant (tetrachloroethene, PCE). For linear configurations of vertical electrodes, the spacing of same‐polarity electrodes is recommended to be about one‐third to one‐quarter of the anode–cathode spacing. Greater coverage could also be achieved by locating additional oxidant injection wells at the divergence of the electric field in linear electrode configurations. Horizontal electrodes allowed greater contact between the injected permanganate and PCE and resulted in faster degradation of PCE compared to vertical electrodes. Pulsed oxidant injection, closer electrode spacing, and electric field reversal also resulted in faster EK‐ISCO remediation.

Electrokinetics applied in remediation of subsurface soil contaminated with chlorinated ethenes – A review

“…The overall pattern is highly complex, partly because the changes induced by the applied electric field are transient (time and space dependent). The often non-linear response in remediation time and energy consumption required to degrade a target level of contaminants indicates the need for a site-specific approach and optimization (Wu et al, 2013). In addition, the relatively low permeability of silt and clay soils coupled with the transient and heterogeneous geochemical conditions result in transient fluid flow and development of negative or positive pore pressure (Gabrieli and Alshawabkeh, 2010), which will influence transport patterns.…”

“…Especially of PO4 3since the phosphate buffering system is often used to buffer pH at the electrodes. Wu et al (2013) took the challenge to model different electrode configurations in EK-ISCO using permanganate. The focus was to achieve optimal coverage of the oxidant.…”

“…Alshawabkeh et al (1999), this model takes into account the contaminant degradation. Greater contact between the injected permanganate and PCE in the model was achieved with horizontal electrodes (Wu et al, 2013). Furthermore, reduced time for remediation can best be achieved by an increased number of electrodes, adopting bidirectional and radial electrode configurations, incorporating oxidant injection wells and a pulsed injection of oxidant (Wu et al, 2013).…”

“…Greater contact between the injected permanganate and PCE in the model was achieved with horizontal electrodes (Wu et al, 2013). Furthermore, reduced time for remediation can best be achieved by an increased number of electrodes, adopting bidirectional and radial electrode configurations, incorporating oxidant injection wells and a pulsed injection of oxidant (Wu et al, 2013). This will come at the cost of increased capital expenditure and in some cases, increased oxidant or energy consumption.…”

Study on the Migration of Phytophthora nicotianae Zoospores in the Soil

“…As reported previously, soil has a stronger adsorption capacity for bacteria than sand, as it has smaller particles and contains more organic matter (Jdvan et al, 1991;Huysman and Verstraete, 1993). This is because the adsorption of microorganisms in soil involve not only physical processes, such as soil adsorption, retention and filtration, but also chemical factors, including electrostatic and the Van der Waals forces between microbial surfaces and soil colloids (Weiss et al, 1995;Rysz and Alvarez, 2006;Wu et al, 2013). Soil types, soil particle sizes, organic matter, microorganism motilities, as well as microorganism motilities and sizes, significantly influence equilibrium adsorption characteristics and coefficients in soil (Coffey et al, 2010;Gyrya et al, 2010;Schinner et al, 2010).…”