New advancements for in situ treatment using electrical resistance heating

Abstract

Electrical resistance heating (ERH) is proving to be an effective technology to rapidly heat the subsurface and, in doing so, removing volatile organic compounds. Practitioners of this technology have observed that other processes (biodegradation, abiotic degradation, hydrolysis, and possibly others) occur to break down the chemicals of concern, and remediation is not solely accomplished through vaporization. Few sites treated using ERH have been monitored during and after treatment to identify and evaluate the processes occurring and assess the contribution of these other biological and chemical processes in the remediation effort so that they may be incorporated in the remediation design.At Fort Lewis, Washington, a landfill has been undergoing ERH treatment in three phases, where chlorinated volatile organic compounds represent the primary chemicals of concern in soil and groundwater. Other chemicals of concern include petroleum products, oils, and lubricants.The Fort Lewis remediation projects provided an opportunity to observe the reactions occurring in the subsurface during ERH and fine-tune the study with each phase of operation. This study is still under way. However, the data gathered to date, which focuses on biodegradation, provides insights into the processes that have been observed. For the Fort Lewis site, biotic and abiotic degradation processes have been observed throughout the range of operating temperatures. At the lower temperature ranges (up to 70• C), biological processes appear to predominate. Above 70• C, abiotic processes become much more active. The goal of this work is to eventually optimize the use of these intrinsic processes in ERH remediation to reduce energy requirements and costs.O

Strategies for Managing Risk due to Back Diffusion

“…Most applications as described in the peer‐reviewed literature have focused on treatment of primary source zones (e.g., NAPL contamination) rather than secondary source zones associated with back diffusion (Beyke and Fleming 2005; Davis et al 2005; Heron et al 2005, 2009, 2013, 2015; Smart 2005; Powell et al 2007; Truex et al 2009; Beyke et al 2014). Assessments of thermal treatment as a DNAPL primary source zone remediation technology based on performance at multiple sites can be found in several papers (McGuire et al 2006; Triplett Kingston et al 2010, 2012; Baker et al 2016).…”

In Situ Thermal Remediation for Source Areas: Technology Advances and a Review of the Market From 1988–2020

“…Accelerated rates of biotic and abiotic degradation mechanisms, including hydrolysis and oxidation, have also long been recognized as valuable by‐products of subsurface heating (e.g., Dablow et al 1995; Powell et al 2007; Truex et al 2007; Suthersan et al 2012), and are increasingly being leveraged as part of combined source zone or heat‐enhanced plume remedies. Elevated temperatures may persist up to two years after thermal operations are terminated (Krauter et al 1996), and in addition to accelerating dissolution and reaction kinetics in the source zone, may also increase the release of electron donors via the hydrolysis of humic and fluvic acids (CDM Smith 2018) and/or downgradient microbial populations capable of degrading contaminants (e.g., Thompson et al 2018).…”

Hazards in Karst and Managing Water Resources Quality

“…For a detailed description of these technologies, the reader is referred to USACE (2006USACE ( , 2009, USEPA (1998aUSEPA ( , 2004, Davis (1997Davis ( , 1998, Powell et al (2007), Kresic (2009c), and Kresic and Mikszewski (2013).…”