Abstract Description

The benefits of antibiotics in controlling diseases and infections are undeniable. However, increased consumption, along with therapeutic misuse and overuse, has led to the emergence of intracellular antibiotic resistance genes (iARGs). Furthermore, most antibiotics are poorly biotransformed after ingestion, resulting in the excretion of 30-90% of the dose, either unmetabolized or as active conjugates, in urine and feces. This accumulation of antibiotics poses a significant issue for the environment and wastewater treatment plants (WWTPs), which are not designed to remove emerging contaminants such as antibiotic resistance genes (ARGs). In this study, iARGs in WWTPs (Baviaanspoort and Zeekoegat) and a drinking water treatment plant (DWTP)(Wallmanthal) was monitored using Quantitative PCR (qPCR) with 21 primer sequences specific to selected iARGs. The removal of iARGs using ferrate (Fe(VI)) at concentrations of 2.5, 5.0, 10.0 and 15.0 mg/L was tested on the Baviaanspoort WWTP effluent with contact times of 0, 5, 10, 15 and 20 minutes. The results indicated that conventional WWTPs were unable to completely reduce the tetA, ermB, and sull ARGs. The observed percentage reductions for these genes were 81.34%, 84.73%, and 71.34% for WWTP A, and 86.19%, 83.09%, and 78.49% for WWTP B, respectively. In contrast, the DWTP successfully eliminated the ermB resistance gene (100% reduction), but could only reduce sull by 60% and resulted in a 9.52% increase in tetA. When Fe(VI) was applied to effluent from WWTP A, the treatment demonstrated effective removal of all three ARGs. The removal efficiencies reached 99% for ermB, 98% for sull, and 99% for tetA at a dosage of 10 mg/L Fe(VI) with a contact time of 10 minutes. These results are significantly higher than those achieved through traditional disinfection methods. This study suggests a promising prospect for using Fe(VI) to efficiently remove ARGs from wastewater, thereby helping to limit their proliferation and transfer in the environment. The ARGs found in the WWTPs could be removed by the addition of 10 mg/L Fe(VI) and a contact time of 10 minutes.