Role of anaerobic sludge digestion in handling antibiotic resistant bacteria and antibiotic resistance genes – A review.

[Display omitted] • Abundance of ARB and ARGs in anaerobic sludge digestion (ASD) are reviewed. • ASD can remove ARGs depending on operational and environmental parameters. • Some ARGs can be enriched after ASD and Firmicutes are commonly found. • Differentiating eARGs from iARGs is critical and should be explored in the future. Currently, anaerobic sludge digestion (ASD) is considered not only for treating residual sewage sludge and energy recovery but also for the reduction of antibiotic resistance genes (ARGs). The current review highlights the reasons why antibiotic resistant bacteria (ARB) and ARGs exist in ASD and how ASD performs in the reduction of ARB and ARGs. ARGs and ARB have been detected in ASD with some reports indicating some of the ARGs can be completely removed during the ASD process, while other studies reported the enrichment of ARB and ARGs after ASD. This paper reviews the performance of ASD based on operational parameters as well as environmental chemistry. More studies are needed to improve the performance of ASD in reducing ARGs that are difficult to handle and also differentiate between extracellular (eARGs) and intracellular ARGs (iARGs) to achieve more accurate quantification of the ARGs. [ABSTRACT FROM AUTHOR]