Field demonstrations of in situ smouldering as a remediation technology

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Switzer, C. and Pironi, P. and Rein, G. and Torero, J.L. and Gerhard, J.I. (2009) Field demonstrations of in situ smouldering as a remediation technology. In: Contaminant Source Zone Characterisation and Remediation (The Geological Society), 2009-04-22.

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Abstract

Smouldering combustion is being developed as a remediation process for soils contaminated with non-aqueous phase liquids (NAPLs). Self-sustaining Treatment for Active Remediation (STAR) is particularly effective on high molecular weight NAPLs such as coal tars and heavy oils, which are among the most recalcitrant of industrial contaminants. Smouldering is a lower energy, flameless form of combustion that is oxygen-limited. Typical smouldering examples involve porous solid fuels that are destroyed by the smouldering reaction (e.g., a smouldering charcoal briquette or smouldering polyurethane foam in furniture that leads to a fire). The oxygen limitation occurs because the oxygen for the combustion reaction has to travel through the porous matrix (in the case of STAR, the soil) to reach the fuel (contaminant). STAR is proving to be particularly effective in the in situ destruction of contaminants, with little to no detectable residue remaining in many cases. Upward scaling of the STAR process has not led to any loss in efficiency. Small-scale ex situ field demonstrations were conducted on two different contaminant and porous media matrices to highlight the broad range of suitable conditions for STAR. The first trial used an idealised mixture of coal tar in coarse sand. Comparison of this field trial data to small and intermediate scale experiments suggests that process efficiency improves with scale. The relative airflow required by the process decreases as scale increases. The second field trial used an industrial mixture of oil wastes from a variety of sources, offering important insights into the effects of moisture and the mechanisms of heat transfer that influence the STAR process. This paper presents laboratory, intermediate and field-scale experiments in the context of the scaling process. Discussion focuses on the key parameters required for successful STAR as well as emissions characterisation for combustion byproducts.

ORCID iDs

Switzer, C. ORCID logoORCID: https://orcid.org/0000-0003-3679-7683, Pironi, P., Rein, G., Torero, J.L. and Gerhard, J.I.;
CORE (COnnecting REpositories)