The use of natural substrates for oil sands process water (OSPW) reclamation offers advantages such as onsite availability and scalability. This study evaluated potential of aged and fresh coarse sand tailings (CST) towards removal of classical naphthenic acids (NAs) from a real OSPW obtained from an oil sands' tailing ponds in Alberta (NAs: 4.87 mg/L). Aged-CST achieved superior removal efficiencies of NAs (96.5 %), aromatics (>
90 %), and acid-extractable organics (∼95 %), compared to fresh-CST, which showed limited removal (∼34.3 %) similar to conventional slow sand filters (∼30-45 %). Although limited surface area of both CST materials (∼1.82 m