Comparative Carbon Footprint of Ex-situ Remediation Facility and On-site Remediation Modes for Contaminated Soil
To evaluate the carbon footprint differences between the emerging ex-situ remediation facility mode and the conventional on-site remediation mode in China, this study employed the SEFA tool to calculate greenhouse gas (GHG) emissions and energy consumption for four typical remediation scenarios. Results indicate that the carbon emission intensity of solidification/stabilization (S/S) in the remediation facility is 12.00% higher than that of on-site S/S, with unit carbon intensities of 66.74 and 59.59 kgCO2e·m−3, respectively, and total energy consumption 11.90% higher. The soil transport segment in the facility S/S contributes 13% of carbon emissions, being the primary reason for its higher total carbon footprint. Conversely, thermal desorption (TD) in the facility exhibits 11.10% lower carbon emissions than on-site TD, with unit intensities of 269.16 and 302.78 kgCO2e·m−3, and total energy consumption 3.97% lower, mainly due to the utilization of landfill biogas as renewable energy for heat and power generation, while soil transport contributes only 3% of emissions. The reagent segment in S/S and the heat supply segment in TD account for 77%–86% and 70%–72% of total GHG emissions, respectively. The study demonstrates that remediation facilities, leveraging advantages such as landfill biogas, can actively aggregate contaminated soil from surrounding areas for centralized thermal desorption, which is beneficial for regional carbon emission reduction in soil remediation.