Comparative Carbon Footprint of Ex-situ Remediation Facility and On-site Remediation Modes for Contaminated Soil

• • Facility-based solidification/stabilization (S/S) exhibits a 12.00% higher carbon footprint (66.74 kgCO2e·m−3) compared to on-site S/S (59.59 kgCO2e·m−3), with total energy consumption 11.90% higher, primarily due to soil transport contributing 13% of emissions. • • Facility-based thermal desorption (TD) achieves an 11.10% lower carbon footprint (269.16 kgCO2e·m−3) than on-site TD (302.78 kgCO2e·m−3), with total energy consumption 3.97% lower, attributed to landfill biogas utilization for heat and power, reducing emissions by 314.65 tCO2e and 115.86 tCO2e, respectively. • • Reagent production dominates GHG emissions in S/S processes, contributing 77%–86%, while heat supply dominates in TD processes, contributing 70%–72%, identifying critical emission reduction levers. • • Sensitivity analysis shows that even with one-way transport distances varying from 15 to 65 km, facility-based TD maintains a lower carbon footprint than on-site TD, demonstrating robust low-carbon advantages.