Removal efficiency and migration characteristics of naphthalene in bioretention facilities: the influences of particulate matter

Abstract Particulate matter (PM), as an important carrier for carrying and transporting runoff pollutants, can significantly affect the behavior and removal efficiency of pollutants in bioretention facilities. In order to control the pollution caused by polycyclic aromatic hydrocarbons (PAHs) in bioretention facilities, the removal efficiency and migration characteristics of typical PAHs-naphthalene were systematically investigated under the influences of PM. The results showed that the removal efficiency of naphthalene was 74% ~ 97% in bioretention facilities under the influences of PM. With the higher naphthalene concentration, the lower rainfall return period, and the longer antecedent drying period, the removal efficiency of naphthalene in each media layer were higher. Furthermore, the PM in the runoff increased the naphthalene adsorption onto media in the first 10 cm depth, which showed more than 80% removal efficiency and lower mobility of naphthalene. The removal efficiency of naphthalene was significantly higher (90% ~ 97%), when the particle size and concentration of PM were 0 ~ 45 µm and 500 mg/L, respectively. This study investigated the important role of PM for naphthalene removal in bioretention facilities, and provided effective guidelines for runoff pollution control, design of stormwater facilities, and assessment risk of PAHs.