Screening of xylene degrading bacteria and optimization of their degradation characteristics in heavily polluted areas

ABSTRACT

Aiming at the problems of high xylene concentration and difficult removal in heavily polluted areas, high-efficient degrading bacteria of volatile organic compounds (VOCs) xylene in heavily polluted areas were selected and screened from sewage sludge, and their degradation characteristics were studied. The response surface methodology (RSM) optimized the optimal degradation conditions. The results showed that the screened degrading strain was identified as Klebsiella by the 16SrDNA technology and named H-16. During the start-up phase of the reactor, the removal rate of xylene by strain H-16 fluctuated, and it was stable above 71.3% for 150 min. At 40°C, the degradation rate is the highest, reaching 63.25%. With an increasing inoculum amount of strain H-16, the degradation rate of xylene gradually increased, and the degradation rate could reach 86.1% when the inoculation amount was 25%. A neutral environment was more conducive to the degradation and removal of xylene. Through the analysis of the model and RSM, the optimal conditions for the degradation of xylene by H-16 were obtained: 38.89°C, pH 6.94 and 18.07%. GC-MS results showed that the possible degradation pathway of xylene began with demethylation, formation of pentene diacid by benzene ring cleavage, and finally oxidation to generate CO₂ and H₂O.

GRAPHICAL ABSTRACT

KEYWORDS:

• Xylene
• degradation bacteria
• select
• degradation characteristics
• response surface methodology

Acknowledgments

We are grateful to the School of Environmental and Municipal Engineering of Tianjin Chengjian University for providing facilities We are indebted to the teachers in the School of Environmental and Municipal Engineering of Tianjin Chengjian University for their patient guidance.

Authors’ contributions

JXZ, XDF and YBT contributed to the study conception and design. Material preparation and collection were performed by HZ, ZTY. JXZ and HZ carried out the experiments. Data analysis were performed by XQW and JYZ. JXZ wrote the manuscript. All authors discussed the results and contributed to the final manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Availability of data and materials

The data that support the findings of this study are available from the corresponding author, [F], upon reasonable request.

Additional information

Funding

This research has not received any support from funds and grants.