Bacterial community structure evolution under prolonged BTEX and styrene exposure: a metagenomic study

ABSTRACT

Benzene, toluene, ethylbenzene, xylenes and styrene (BTEXS) are toxic pollutants that co-occur in wastewater effluents from petrochemical and chemical industries. Seeking effective and efficient treatments for these effluents is crucial in eliminating serious health and environmental issues that would otherwise arise from the anthropogenic release of BTEXS. This work examined the evolution in bacterial profiles under prolonged BTEXS enrichment and identified biomarkers associated with the enriched microbial community. The volatile suspended solids (VSS) increased by 24% within 15 months, indicating that the microbial community had evolved to assimilate BTEXS as an energy and carbon source. Six key biomarkers and three indicative biomarkers were identified at the bacterial order level. Rhizobales, Burkholderiales and Actinomycetales were identified as key biomarkers of the core BTEXS-degrading population while Sphingobacteriales, Flavobacteriales and Bacteroidales were identified as key biomarkers of the secondary BTEXS-degrading population. Xanthomonadales, Pseudomonadales and Clostridales may serve as indicative biomarkers of the operating conditions (i.e. BTEXS loading and oxygen levels). This new knowledge is beneficial to engineers in selecting seed inoculum and monitoring reactor stability. Furthermore, it potentially enables engineers to leverage on innate microbial characteristics to develop biological treatments for an effective and efficient remediation of BTEXS-laden wastewater effluents.

KEYWORDS:

• Benzene
• toluene
• ethylbenzene
• xylenes
• styrene
• next-generation sequencing
• biomarkers

Acknowledgements

The authors gratefully acknowledge the financial support from the Research Grants Council of Hong Kong under the Collaborative Research Fund (CRF) (Project title: Fe-enhanced primary sedimentation and sludge acidogenesis for resources (P and PHA) recovery during wastewater treatment [CEE-2]).

Additional information

Funding

This work was supported by the Research Grants Council of Hong Kong: [Grant Number Collaborative Research Fund (CRF)].

Notes on contributors

Amy G Y Tan

Dr Amy G Y Tan is a Postdoctoral Fellow in the Department of Civil and Environmental Engineering at The Hong Kong Polytechnic University. Her research interest lies in bacterial bioremediation and up-cycling, particularly the underlying metabolic mechanisms and their exploitation to address the existing environmental and industrial problems.

Jing-Yuan Wang

Dr Jing-Yuan Wang is an Associate Professor at the Nanyang Technological University (NTU), Singapore. His expertise includes solid waste resource management, contaminated site remediation and environmental management. His current research interests are focused on decentralised waste and wastewater resource recovery, co-digestion of brown water and food waste, land reclamation of closed dumping ground and bioconversion of plastic waste into biodegradable plastic polymers.

Po-Heng Lee

Dr Po-Heng Lee is an Assistant Professor at The Hong Kong Polytechnic University. His research emphasises biochemical processes for mining resources from wastewater using the computational thermodynamics and meta-omic approaches, especially in relation to fermentation, anaerobic digestion and anaerobic ammonium oxidation (Anammox)-based processes.