Biodegradation of waste asphalt shingle by white rot fungi

Waste asphalt shingle (WAS) has traditionally been disposed of by landfilling due to environmental concerns surrounding Polycyclic aromatic hydrocarbons in WAS, which may potentially leach out, causing environmental pollution. However, this disposal method has been less environmentally acceptable and less cost effective than in the past due to concern on land resources. This study evaluates the potential of degradation of WAS, therefore reducing the polycyclic aromatic hydrocarbons (PAHs) content, by exploiting microbial biodegradation. The white rot fungus Phanerochaete chrysosporium was tested for its potential to degrade waste asphalt shingle binder. The biodegradation process was analyzed and quantified by both Fourier-transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC). Results illustrate that P. chrysosporium can degrade WAS binder. GPC analysis indicates that the small asphaltic molecules were biodegraded preferentially by P. chrysosporium. The PAHs content of the WAS binder increased initially during fungal biodegradation, but subsequently decreased with the progression in biodegradation to a level lower than that of the original shingle binder. Results from this study could be used to develop solutions to the sustainable management of waste asphalt shingles.