Leaching of polycyclic aromatic hydrocarbons and heavy metals from stored reclaimed asphalt pavement

Abstract

The construction, maintenance, and expansion of roads results in the generation of huge quantities of milled asphalt viz. reclaimed asphalt pavement (RAP). However, recycling of RAP is rarely followed in developing countries such as India. Due to rainfall, stockpiled RAP in open areas may generate leachate containing polycyclic aromatic hydrocarbons (PAHs) and heavy metals, raising concern about the stockpiling of RAP. This study addresses the environmental concerns associated with the possible leaching of PAHs and heavy metals from RAP by batch leaching procedures. The leachate predominantly contained three-, and five-ring PAHs. ΣBenzo(k)fluoranthene (ΣBkF) showed the highest concentration (397 µg/kg), followed by ΣPhenanthrene (ΣPHE) (290 µg/kg) among the all sixteen PAH compounds analysed. The results showed that the leaching potential of RAP was rather weak; hence RAP cannot be classified as hazardous waste. Further, none of the samples exceeded the soil risk-based threshold (RBT) values of PAH for residential or commercial settings indicating negligible risk.