Enabling Adaptive UV and Solar-Based Disinfection Systems to Reduce the Persistence of Viral Pathogens in Wastewater for Sustainable ReuseEPA Grant Number: R835826
Title: Enabling Adaptive UV and Solar-Based Disinfection Systems to Reduce the Persistence of Viral Pathogens in Wastewater for Sustainable Reuse
Investigators: Nguyen, Thanh (Helen) H. , Guest, Jeremy S , Shisler, Joanna L
Institution: University of Illinois at Urbana-Champaign
EPA Project Officer: Packard, Benjamin H
Project Period: September 1, 2015 through August 31, 2018 (Extended to August 31, 2020)
Project Amount: $750,000
RFA: Human and Ecological Health Impacts Associated with Water Reuse and Conservation Practices (2014) RFA Text | Recipients Lists
Research Category: Water , Health
Water reuse is a necessity in this new era of water scarcity. Used water must be treated so that it is safe in the event that humans use it indirectly or directly. Sunlight/solar disinfection of recycled water is attractive for public and private entities because it is inexpensive and could be an entirely passive process with appropriate system design. For communities with more resources, disinfection using high energy ultraviolet (UVC) or chlorination is often preferred. While chlorination is inexpensive, high levels of organic matter in wastewater will allow the formation of toxic disinfection byproducts. Unfortunately, both UVC and solar disinfection of viruses are hindered by incomplete knowledge of virus disinfection mechanisms in water reuse. This lack of understanding represents a critical knowledge gap that prevents utilities and regulatory agencies from evaluating treatment system designs to ensure the protection of human health. The following hypotheses will be tested using rotavirus and adenovirus, two viruses that are of concern to public health: 1) the phenotypic and genotypic differences between virus strains can be used to identify the molecular mechanisms responsible for viral susceptibility to solar and UVC inactivation, 2a) photo-oxidation of viruses depends on the reactions between viruses and reactive radicals formed upon irradiation of wastewater, 2b) direct effect of UVC irradiation on viruses depends on the irradiation wavelength and the specific UV absorbance (SUVA) of the wastewater, and 3) human health risk and life cycle ecological impacts can simultaneously be reduced by leveraging solar disinfection. The project objectives include: 1) Determine the molecular mechanisms responsible for virus inactivation; 2) Determine factors required for effective virus inactivation by natural sunlight and UVC; and 3) Develop pond and UVC design guidelines to achieve reliable virus inactivation and elucidate trade-offs across and within dimensions of sustainability.
We will meet our first objective by using viral genetics to identify the genes that are responsible for resistance to disinfection by solar or UVC irradiation, and then determine how damage of the viral proteins cause conformational and molecular alterations rendering the viral particle inert. The second objective will be met by conducting inactivation experiments using either sunlight or monochromatic and polychromatic UVC for both well-defined and unpurified wastewater samples collected from a reuse facility in Illinois. Objective 3 will be met by using virus inactivation data to develop a mechanistic model of solar and UVC virus inactivation, which will be integrated with risk assessment, life cycle assessment (LCA), and life cycle costing (LCC) models under uncertainty to evaluate treatment system design alternatives to enable wastewater reuse for irrigation.
Our completed work will provide a new framework to understand how solar and UVC irradiation inactivates viruses. Because adenoviruses are the most resistant pathogen to UVC disinfection, we reason that conditions assuring their neutralization also will effectively remove other pathogens. The molecular knowledge obtained from this project will contribute to the development of an accurate assessment of public health risks related to viral pathogens in wastewater reused for irrigation and recreational purposes. Finally, a framework for the sustainable design of waste stabilization ponds will be established by integrating locality-specific factors (e.g., climate) with LCA, LCC, risk and inactivation models.