Bioaugmentation process for PAHs contaminated soil remediation through microbial inocula from anaerobic treatment of lignocellulosic substrate

In the present work, an anaerobic bioremediation treatment was investigated for reclamation of polycyclic aromatic hydrocarbons (PAHs) contaminated soil. The PAHs contaminated soil was artificially prepared and seven different contamination conditions were tested. In particular, four soils were contaminated solely by naphthalene (A), anthracene (B), pyrene (C) and benzo[a]pyrene (D), respectively, whereas, three soils were contaminated by benzo[a]pyrene coupled with one of the other investigated PAHs (i.e. A+D, B+D, and C+D tests). Such conditions were tested in order to study the possible degradation kinetic for the single involved PAH (with aromatic rings ranging from 2 to 5) as well as for PAHs mixed with a 5-aromatic rings contaminant (i.e. benzo[a]pyrene). The investigated treatment was carried out in bioaugmented condition through two microbial inocula obtained from anaerobic digestion tests on lignocellulosic substrate. In more detail, the two inocula were differently enriched through experiments characterized by sequential re-inoculation on new substrate, for its subsequent treatment, every 24 h and 96 h, respectively. The present study focused on the PAHs degradation efficiency and pathways, and microbiological abundance characterization, thus providing a comprehensive and interdisciplinary view to assess the feasibility of the suggested treatment in the field of PAHs contaminated soil remediation.