ABSTRACT
In the U.S., spray irrigation is the most common method used in agriculture and supplementing with animal wastewater has the potential to reduce water demands. However, this could expose individuals to respiratory pathogens such as Legionella pneumophila and nontuberculosis Mycobacteria (NTM). Disinfection with methods like anaerobic digestion is an option but can increase concentrations of cytotoxic ammonia (personal communication). Our study aimed to model the annual risks of infection from these bacterial pathogens and the air concentrations of ammonia and determine if anaerobically digesting this wastewater is a safe option. Air dispersion modeling, conducted in AERMOD, generated air concentrations of water during the irrigation season (May-September) for the years 2013-2018. These values fed into the quantitative microbial risk assessments for the bacteria and allowed calculation of ammonia air concentrations. The outputs of these models were compared to the safety thresholds of 10-4 infections/year and 0.5 mg/m3 , respectively, to determine their potential for negative health outcomes. It was determined that infection from NTM was not a concern for individuals near active spray irrigators, but that infection with L. pneumophila could be a concern, with a maximum predicted annual risk of infection of 3.5 × 10-3 infections/year and 25.2% of parameter combinations exceeding the established threshold. Ammonia posed a minor risk, with 1.5% of parameter combinations surpassing the risk threshold of 0.5 mg/m3 . These findings suggest that animal wastewater should be anaerobically digested prior to use in irrigation to remove harmful pathogens.
Subject(s)
Risk Assessment/methods , Waste Disposal, Fluid/methods , Wastewater , Water Purification/methods , Aerosols , Agricultural Irrigation/methods , Agriculture/methods , Air , Air Movements , Ammonia/chemistry , Animals , Legionella pneumophila , Legionnaires' Disease/microbiology , Manure , Microfluidics , Mycobacterium/metabolism , Probability , Risk , Swine , WaterABSTRACT
Several lines of evidence suggest the presence of severe acute respiratory coronavirus-2 (SARS-CoV-2) in wastewater. The use of sewage water for irrigation is common in many developing countries, and it is only partially treated in the majority of countries with less than 10% of collected wastewater receiving any form of treatment globally. Wastewater is unsafe for human and animal consumption and contains impurities and microbial pathogens. Here, we pose the question of whether the reuse of untreated or partially treated wastewater for irrigation can expose susceptible populations and pets, leading to COVID-19 disease recurrence in the community? It is imperative to study the ecological relationships between humans, animals, and environmental health in relation to COVID-19 to contribute to a "One Health Concept" to design preventative strategies and attain optimal health for people, animals, and the environment.