Batch biodegradation of PAHs in mixture by Mycobacterium frederiksbergense: analysis of main and interaction effects

Biodegradation is an effective technique to remediate soil and water contaminated with polycyclic aromatic hydrocarbons (PAHs). In the present experimental study, Mycobacterium frederiksbergense, a fast growing mycobacterium, was used to degrade anthracene, naphthalene and pyrene in mixture each at initial concentrations varying between 1 and 50 mg l⁻¹. Experiments were conducted according to the 2³ factorial design at the low (1 mg l⁻¹) and high (50 mg l⁻¹) levels of the PAHs in combination, to identify the main and interaction effects of the compounds on their biodegradation. The results showed that the PAH removals varied 54–81% when each PAHs were at low concentrations in the mixture and 67–89% at their higher concentration combinations. Statistical analysis of the results in the form of ANOVA and Student t test indicated significant role played by the main effects of pyrene on its degradation. Similarly on anthracene degradation, interaction effect with pyrene was found to be highly significant with P value less than 0.1.