Can thermal soil remediation be sustainable? A case study of the environmental merit of the remediation of a site contaminated by a light non-aqueous phase liquid (LNAPL)

摘要

When evaluating remediation technologies for contaminated soil and groundwater, the beneficial effects of the remediation, namely cleaner soil and groundwater, are mostly emphasized without consideration of the environmental impact of the remediation activities themselves. In the present study, the environmental impact of two soil remediation techniques was evaluated. Based on the detailed analysis of a case study, the results of a life cycle-based analysis (Risk Reduction, Environmental Merit and Costs (REC)) were compared with the results of a best available technology not entailing excessive costs (BATNEEC) analysis, a method that is currently applied in Flanders (Belgium) to evaluate the feasibility of remediation technologies for soil and groundwater. According to the REC analysis, in situ thermal treatment showed a lower global environmental impact than soil excavation and off-site treatment, mainly because there were fewer emissions from the transport of contaminated soil. Within the environmental aspects group of the BATNEEC method, soil excavation performed better than thermal soil remediation because it obtained a better score to meet the legal objectives for soil and groundwater quality. It also showed fewer environmental liabilities and obtained a better score for a decrease in the contaminants' content in soil and groundwater. The BATNEEC method does not take into account the emissions from the transport of the soil. Despite these differences between both methods, thermal remediation technology obtains the best overall score in terms of both assessment methods (taking into account the environmental, financial, and technical aspects). Although an life cycle analysis (LCA) based evaluation method is much more complex and requires much more data than a classical BATNEEC analysis, both evaluation tools could be used in a complementary way. A preliminary selection of remediation technologies could be based on a BATNEEC analysis, followed by a detailed analysis of the selected remediation options by means of LCA.