Occurrence and\nRemoval of Antibiotics in Wastewater\nTreatment Plants during the COVID-19 Pandemic

To evaluate the presence, removal, and concentration\ntrends of\nantibiotics in wastewater treatment plants (WWTPs) during the COVID-19\npandemic, monthly influent and effluent samples were collected from\nfour WWTPs in Minnesota to measure 26 antibiotics within six major\ncategories from August 2020 to July 2022. Profiles of the studied\nantibiotics in each class were dominated by the compounds designated\nfor human use in both influents and effluents. High influent concentrations\nof azithromycin (123–1031 ng/L) were observed during the initial\nstages of the COVID-19 pandemic, and levels peaked approximately 3–5\nweeks after spikes of weekly COVID hospitalizations and reported cases.\nThe concentration of azithromycin in influents positively correlated\nwith weekly reported COVID cases (Pearson, <i>r</i> = 0.95, <i>p</i> < 0.001) and COVID hospitalizations (Pearson, <i>r</i> = 0.85, <i>p</i> < 0.05) with variably delayed\nresponse patterns for large versus small-scale WWTPs in different\nstages of the COVID-19 pandemic. WWTPs effectively removed most antibiotics\n(on average 47–88% for sulfamethoxazole and 53–80% for\nciprofloxacin), while negative removals were occasionally observed\n(generally for low influent concentrations). The results of this 2-year\nstudy highlight that the COVID-19 pandemic affected the temporal dynamics\nof antibiotics authorized for the treatment of COVID-19 coinfections.