The aim of this work was to explore the effect of lowering pH and application of surfactants (Brij 35, Tween 20 and Saponin) in increasing bioavailability and biodegradability of benzene and o-xylene (BX) as two hydrophobic VOCs in a liquid mixture. All experiments were conducted at neutral and acidic pH to evaluate the effect of population change from bacteria to fungi on the BX biodegradation. The experiments demonstrated that acclimating wastewater inoculum at pH 4 increased the fungal to bacterial ratio. An increase of 11% for benzene and 22% for o-xylene was observed at pH 4 unamended-culture as compared to pH 7. Brij 35 was chosen as the optimum surfactant which was favorable for enhancing the bioavailability of BX at pH 4. Fitting the experimental data to pseudo first-order biodegradation kinetics model showed the BX were biodegraded faster in the presence of optimum surfactant at pH 7 than pH 4.
Keywords: Acidic pH; Biological treatment; Fungi; Hydrophobic volatile organic compounds; Surfactants.
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