A Reactive Transport Model Considering the Bioavailability of PAHs Based on Lagrangian Reactive Particle-Tracking Method

Bioavailability is one of the important concepts affecting bioremediation of PAHs-contaminated site but often ignored in reaction transport models, resulting in failure of site repair prediction and incorrect evaluation of important parameters. A reaction transport model considering bioavailability is constructed that uses transition probability and Lagrangian methods to analyze the transport and reaction of PAHs in soil rather than the conventional reaction transport model. This method avoids the numerical problems associated with solving the transmission problem directly. The effects of soil physicochemical properties and biodegradation rate on the reaction and migration were evaluated using phenanthrene as model pollutant. It shows that low biodegradation rates are detrimental, may lead to elevated PAHs concentrations in liquids, prolong PAHs bioaccessibility, and create a risk of leakage, so the appropriate addition of reagents such as enzyme preparations is effective, but simply increasing the biodegradation rate is insufficient for contaminant removal from soil. Through sensitivity analysis, it was determined that the most important factor affecting the residual PAHs in soil should be the physical and chemical properties of soil, which provides a basis for the addition of surfactants, while it is also pointed out that the toxicity evaluation of surfactants is of great significance in soil remediation.