Collaborative Research: Environmental Fate and Impacts of Quaternary Ammonium Compounds Following Increased Use During the SARS-CoV 2 Pandemic

The novel coronavirus SARS-CoV-2 is responsible for the global pandemic of COVID-19. Disinfection use to kill SARS-CoV-2 on surfaces and for handwashing has increased dramatically in response to the pandemic. A large number of disinfectants have been approved for usage as SARS-CoV-2 disinfectants, many of which contain quaternary ammonium compounds (QACs). QACs will inevitably be sent to wastewater treatment plants and some will end up in receiving waters. The effect of these disinfection chemicals on the operation of wastewater treatment plants and receiving waters is largely unknown. These compounds may also contribute to the spread of antibiotic resistance microorganisms, an issue of global health importance. The goal of this project is to address these major gaps in our knowledge on QACs to provide information to help limit any environmental impact. The goal will be achieved by assessing QACs in wastewater treatment plants and determine what happens to them in different plant processes and receiving waters. Successful completion of the proposed research will provide the information needed to assess the risk of QACs to protect public health while minimizing environmental persistence and impacts. The project will lead to collaborations with wastewater treatment systems operators to improve operations and the development of educational videos for middle school environmental science students to enhance scientific literacy of the Nation. Quaternary ammonium compounds (QACs) are active ingredients in over 200 disinfectants currently recommended for use to kill the SARS-CoV-2 (COVID-19) virus. Increased use of these disinfectants for hand washing and surface cleaning continues, and the biological impacts of increasing chemical loadings to wastewater treatment plants and surface waters is largely unknown. The goal of this work is to assess the potential impacts of increased QAC loadings to wastewater treatment plants and subsequently aquatic and soil environments. This goal will be achieved through specific research objectives to: 1) Assess QAC levels in wastewater treatment facilities, surface waters, and sediments; 2) Quantify degradation rate constants for QACs and predict persistence in surface waters; and 3) Understand how increased QAC loadings to anaerobic digesters and water environments affects antibiotic resistance. Twelve wastewater treatment plants employing various biological and chemical treatment processes will be sampled seasonally for three years to assess influent, liquid effluent, and biosolids effluent QAC loadings. Sediment samples near outfalls will also be sampled. A mass balance on QACs across individual unit operations will be conducted at two treatment plants. Lab-scale biodegradation and photolysis experiments will be conducted to generate rate removal constants to predict persistence in environmental waters. Lab-scale anaerobic digester experiments will be conducted to determine the impact of increasing concentrations of specific QAC classes on antibiotic resistance. Samples from full-scale plants will also be analyzed for changes in antibiotic resistance. The SARS-CoV-2 pandemic brings large uncertainty regarding the amount of QACs that will be used and their specific environmental impacts. By combining lab-scale and full-scale studies we will generate data on classes of QACs and individual QACs that can be used for risk assessments and assessing their impacts on antibiotic resistance. This research is timely and transformative given the expectation of increased loadings of QACs due to the COVID-19 pandemic and long-term changes in consumer and business purchasing of products containing QACs.