Modification of PAHs Biodegradation with Humic Compounds

The effect of extractable humic substances (EHS) on the bioremediation of phenanthrene in a slurry phase was investigated using adapted microorganisms with polycyclic aromatic hydrocarbons (PAHs). Two concentrations of EHS were used: 150 and 30 mg/kg soil. The phenanthrene concentration was 500 mg/kg soil. The results showed that the trend of biodegradation was increased after four weeks retardation. These tests showed that humic compounds could overcome the bond between the soil and phenanthrene in the presence of the bacterial consortium. The bacterial density in the medium with EHS was about six-fold greater in magnitude than in the medium without the humic compounds. The chemical relationship between phenanthrene and the humic substances in the form of a phenanthrene-humic-soil complex or phenanthrene-humic is loosely associated and reversible. Therefore, after the initial inhibition by humic substances, the bioavailability of phenanthrene increases.