Deciphering the treatment performance, microbial community responses, and behavior of antibiotic resistance genes in anaerobic sequencing batch reactors under graphene exposure†

Graphene has garnered significant attention due to its unique and remarkable properties. The widespread application of graphene materials in numerous fields inevitably leads to their release into the environment. This study examines the long-term impacts of graphene on anaerobic sequencing batch reactors. The low-concentration graphene (5 mg L⁻¹) exhibited a significant inhibitory effect on the removal of chemical oxygen demand, while the high-concentration group (100 mg L⁻¹) was less affected. The transmission electron microscopy and Raman spectroscopy results demonstrated that the anaerobic sludge could attack graphene materials, and cell viability tests showed that high concentrations of graphene were more conducive to microbial attachment. High-throughput sequencing revealed significant alterations in the microbial community structure under graphene pressure. Methanobacterium and Actinomyces gradually became the dominant genera in the high-concentration group. Network analysis showed that graphene increased the complexity and interaction of microbial communities. Additionally, high-throughput qPCR analysis demonstrated that graphene influenced the dynamics of antibiotic resistance genes, with most exhibiting increased abundance over time, especially in the low-concentration group. Consequently, when considering the application of graphene in wastewater treatment, it is crucial to evaluate potential risks, including its effects on system performance and the likelihood of antibiotic resistance gene enrichment.