The emergence of antibiotic resistance genes (ARGs) and antibiotic-resistant bacteria (ARB) in natural and engineered ecosystems has raised human health concerns in recent years. The prevalence and spread of ARGs and ARB have been significantly accelerated by the widespread use of antibiotics in sectors such as healthcare and agriculture, posing threats to human and animal health, the environment and ecosystems.

WaterRA Project 2058, Understanding and reducing the spread of antibiotic resistance in anaerobic sludge digestion, investigated how anaerobic digestion impacts the fate and removal of ARGs in sludge from a wastewater treatment plant (WWTP). Researchers used lab-scale experiments, with sludge from a full-size WWTP, to test the impact of different anaerobic conditions on ARGs. Ten ARGs representing different antibiotic classes and one integrase gene (intI1) of class 1 integron, involving ARGs horizontal gene transfer, were chosen for the study. They found that temperature-phased anaerobic digestion (TPAD) reduced ARGs by over 92%. The researchers further developed an innovative, waste-driven technology that pre-treats the sludge with free ammonia (FA) before mesophilic anaerobic digestion. FA pretreatment combined with mesophilic anaerobic digestion enhanced total ARG removal by 15% compared to conventional mesophilic anaerobic digestion alone.

These findings feature effective strategies for mitigating the spread of antibiotic resistance through wastewater treatment, offering crucial benefits for public health and environmental protection. The research report, available now for WaterRA members to download, highlights that:

• TPAD and FA pretreatment can reduce antibiotic-resistant genes in sludge.
• Implementing these methods in wastewater treatment plants can help curb the spread of antibiotic resistance.

This event, FREE and exclusively for WaterRA members, will provide an opportunity to learn more about the project outcomes, and recommendations to advance this research.