Soils contaminated with persistent PAH priority pollutants represent a long-term source of contaminant release into surface water, groundwater, edible biota and air exposure pathways. Current remediation methods are either relatively slow or have unintended consequences such as soil damage, high-energy usage or generation of more noxious PAH derivatives. Thus, there is a pressing need for more efficient and sustainable remediation of soils contaminated with PAHs and other recalcitrant lipophilic organic pollutants. Our group has developed a novel pyrolytic method for ex-situ remediation of soils contaminated with heavy petroleum hydrocarbons that contain PAHs. This approach can rapidly and reliably remove total petroleum hydrocarbons (TPH) and PAHs with lower energy requirements and better post-treatment soil fertility than other ex-situ thermal remediation approaches. However, our studies also revealed potential tradeoffs between treatment intensity, soil detoxification efficacy and soil fertility restoration. Using the Distributed Activation Energy kinetic model for the pyrolysis of petroleum-contaminated soils, we simulated the operation of a non-isothermal rotary kiln reactor that may be used for ex situ treatment of soils contaminated with PAHs. Model predictions were compared to experimental data obtained by treating two contaminated soils. The overall TPH and PAH reductions predicted by the model agreed well with the experimental data for all the conditions considered. More importantly, our model was able to explain the trade-offs observed in our earlier study between pyrolysis treatment intensity, soil detoxification and soil fertility restoration. We will finally present results that extend our theoretical models to full-scale kiln reactors. Our focus here will be on providing guidelines for estimating the optimal operating conditions (pyrolysis temperature and residence time) for contaminated soils with various soil properties and pollutant content.

Pyrolytic treatment of soils contaminated with polyaromatic hydrocarbons: Kinetics and reactor design

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.