Bioremediation of hydrocarbons from contaminated wood: A proof-of-concept study

A proof-of-concept study to evaluate the biological removal of hydrocarbons (naphthalene, n-hexadecane, and fuel oil #2) from contaminated wood (Southern yellow pine) was conducted using C-14-Iabeled tracers and gas chromatography. Contaminated wood was brought in contact with n-hexadecane-degrading Pseudomonas aeruginosa PG201 or naphthalene degrading environmental isolates by the application either on mineral medium agar or filter paper containing a previously grown biomass (overlay technique). The experiments showed a significant acceleration of naphthalene removal by biomass. Due to biodegradation combined with evaporation, naphthalene was nearly completely removed (up to 90-98 %) in 4-8 days from freshly contaminated 6 mm- and 17 mm-thick wood samples. The removal of a less volatile hydrocarbon, n-hexadecane, was less efficient, at 40-60% in 20-40 days, with the only variable significantly affecting this pollutant's removal rate being the moisture content of the medium. Biodegradation experiments with standard heating fuel oil #2 (a representative real-world contaminant) resulted in significant removal of light hydrocarbons (C-10-C-16), i.e., more mobile/volatile substrates, in 3 weeks (up to 70 %) whereas heavier hydrocarbons (C-17-C-19) were less affected. Pollutant mobility in both wood and aqueous media was shown to be the crucial factor affecting the removal efficiency. These results point toward a promising technique to reclaim wooden structures contaminated with volatile and semi-volatile chemicals.