New insights into thermal desorption remediation of pyrene-contaminated soil based on an optimized numerical model

Thermal desorption (TD) is known as an effective technique to remediate PAHs-contaminated sites. However, effectively removing PAHs using TD while saving time, and energy, and minimizing soil damage remains a challenge. In this study, we examined the combined effects of various factors on the removal efficiency of pyrene (PYR) by TD and developed an optimal numerical model based on conducting a series of soil experiments. The results showed that temperature (T) and time (t) promoted the desorption of PYR, while water (S_w) and organic matter (f_om) were just the opposite. Besides, water and organic matter had a synergistic effect proportionally. It was found that adjusting the soil-water ratio (which can be controlled by organic matter) maximized the desorption rate of PYR. An ideal S_w/f_om 1.56 and a minimized recommended temperature (173 °C) were proposed based on the model. Finally, the efficacy of the optimized scheme was validated in real-world site soil. These findings not only mechanistically revealed the desorption behavior of PYR under the influence of various factors, but also provided an optimized scheme for efficiently removing PAHs using TD, thereby accelerating the remediation process and reducing energy consumption. The modeling ideas and conclusions obtained may be applicable to other PAHs, guiding the effective remediation of PAHs-polluted sites.