Effect of surfactants at natural and acidic pH on microbial activity and biodegradation of mixture of benzene and o-xylene

• Published in: Chemosphere (Oxford) 2020-12, Vol.260, p.127471-127471, Article 127471
• Main Authors: Khoramfar, Shooka, Jones, Kim D., Ghobadi, Jalil, Taheri, Parisa
• Format: Article
• Language: English
• Subjects: Acidic pH; Biological treatment; Fungi; Hydrophobic volatile organic compounds; Surfactants
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2020.127471

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. [Display omitted] •Acidic pH of 4 induced fungal growth and BX biodegradation compared to the neutral pH.•Removal of benzene and o-xylene were enhanced by addition of Brij 35 and Saponin.•The optimum doses of surfactants were 0.1 CMC Saponin and 2 CMC Brij 35 at pHs 7 and 4, respectively.•Tween 20 showed toxicity toward microbial growth at neutral and acidic pH.•First-order kinetics model was successfully fitted to the experimental data.