A smart wastewater treatment approach to reduce the spread of antimicrobial resistance at sources

Summary

Hospitals and nursing homes are important point sources of antibiotics (AB), antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARG) to the urban sewage system. Since urban wastewater treatment plants (WWTPs) are incapable to fully remove these contaminants from wastewater, those are released uncontrolled into the environment with yet unknown implications and risks to human and animal health. In the proposed revised EU urban wastewater treatment directive larger WWTPs are requested to establish a fourth treatment barrier for removing micropollutants. We assume that will also concern and apply to antimicrobial resistance in the future. However, currently, knowledge about the effectiveness and limitations of fourth (or fifth) barrier treatment solutions particularly targeting AB, ARB, ARGs, as well as about their reliability at full-scale operation, particularly in cold climates, is poor. Since the directive will also urge polluters to take more responsibility in anticipation of reuse of resources from wastewater, polluters possibly need to look into point-source treatment solutions in the future, which hinder contamination of the sewage system already upstream. A novel local treatment approach for the removal and destruction of AB/ARB/ARGs in wastewater from point sources, such as discrete hospital sections, nursing homes, and animal husbandries and the industry is presented. The system is based on ozonation and an advanced oxidation process (AOP). It is smaller, lower in maintenance and is more mobile than existing systems. This is due to a higher ozone performance ratio, simultaneous treatment of liquid and sludge phases and because treatment focuses only on reducing hazardousness of antimicrobial resistance. The aim was to demonstrate and test the performance of the treatment system regarding disinfection of ARB and ARGs in hospital wastewaters. Wastewater was collected at a hospital and was subjected to ozonation and AOP in a pilot-scale system operated in recirculation. The disinfection performance was investigated qualitatively and quantitatively by measuring the efficiency to remove 384 selected genetic markers in treated samples. In addition, relative changes in the patterns of organic substances in the wastewater due to treatment was determined by non-target analysis. Preliminary results show a 95% and 98,9% reduction in the total number of detected genetic markers due to ozonation and AOP, respectively. Genes being removed fastest were mainly coding for Vancomycin and Trimethoprim, while genes coding for Tetracycline, integrons and MGE were more persistent to the treatment. The change in patterns of organic substances will be presented in form of a heatmap based on non-target analysis. Further tests are currently ongoing at the hospital and our findings and learnings from those tests will be presented and discussed.