Mixed veterinary antibiotics removal and effects on anaerobic digestion of animal wastes: Current practices and future perspectives

Veterinary antibiotics (VAs), extensively utilized in animal healthcare, are not present as a single compound in the environment and ultimately present as a mixtures. A significant research gap persists regarding the removal of mixed VAs (MVAs) and their influence on anaerobic digestion (AD) process. It is crucial to delve into the capabilities of AD in eliminating MVAs concern effectively. In this review, a state-of-art overview of MVAs removal and their impacts on AD process was provided for first time. Most of MVAs studies have concentrated on mixtures containing Tetracyclines (TCs), Fluoroquinolones (FQs), and Sulfonamides (SAs) with a leading interest by China. The collected data reveals that MVAs generated a competition on their biological degradation and their adsorption into sludge during AD process. These phenomena exhibited lower MVAs removal at approximately 60 +/- 3.0 % compared to individual removal performances of antibiotics by AD. TCs tend to have a greater inhibitory impact on biogas production compared to other antibiotic groups, FQs could stimulate biogas production, while combining different antibiotic groups worsened the biogas production. The inoculum content appears to play a significant role in mitigating the effects of MVAs on biogas production. While MVAs effects on AD's microbial activity were found to be contradictory depends mainly on the antibiotics group. Nevertheless, the above influences are riddled with uncertainties that require more extensive investigation. This review aims to broaden our understanding of MVAs interaction within the AD process, examines antibiotic mixtures' impact on ADdriven removal efficiency, and outlines future research directions.