CAREER: Drinking water treatment & distribution - the environmental training grounds for pathogens to evade the human immune system

In the United States (US), approximately 85% of the population is supplied with drinking water (DW) from centralized water treatment plants that are designed and built using treatment trains (TTs) that combine different unit processes (e.g., coagulation, flocculation, filtration, and disinfection) to produce clean water which meets the federal/state quality and safety standards for human consumption. Although water utilities add residual disinfectant (e.g., chlorine or chloramine) to treated DW to control and prevent the regrowth of microorganisms in both the distribution systems (DS) and premise plumbing, treated/disinfected DW still contains a diversity of microorganisms including water-associated pathogens (DWPIs) such as Legionella pneumophila and nontuberculous mycobacteria (NTM).

The overarching goal of this CAREER project is to test the hypothesis that DWPIs (e.g., NTM) which survive chemical oxidant stressor (COS) exposure during water disinfection will be more virulent at causing disease due to the similarities between the COS found in the human body during infection and TT/DS disinfection processes. To test this hypothesis, the Principal Investigator (PI) proposes to use a pilot DW treatment plant and laboratory-scale systems to evaluate, quantify, and identify how different TT and DS protocols impact COS generation during water disinfection and how this in turn impacts the survival of DWPIs and their ability to cause infection.

The successful completion of this project will benefit society through the generation of new fundamental knowledge to inform the design of more effective DW TT and disinfection operational protocols to minimize and mitigate the seeding and growth of DWPIs in drinking water distribution systems and premise plumbing. Additional benefits to society will be achieved through student education and training including the mentoring of one graduate student and one undergraduate student at the University of Pittsburgh.

Despite the broad range of physical and chemical processes used in their treatment trains (TT), water treatment plants are home to complex microbial communities that survive the exposure to chemical oxidant stressor (COS) generated during disinfection to seed drinking water distribution systems (DS) and premise plumbing with water-associated pathogens (DWPIs) including nontuberculous mycobacteria (NTM) that cause respiratory infections. Although several recent studies show a clear link between the strains of NTM found in household DW and those infecting people, a fundamental understanding of this link has remained elusive.

This CAREER project will address this critical knowledge gap. The specific objectives of the research are to 1) Investigate and evaluate the influence of different TT configurations on the functional microbial community and abundance of NTM; 2) Quantify the impacts of TT/DS associated COS exposure on the survival and pathogenesis of NTM; and 3) Identify the mechanism(s) responsible for changes in NTM virulence due to repeated exposure to disinfection generated COS.

The successful completion of this project has the potential for transformative impact through the generation of new knowledge to 1) advance the fundamental understanding of how DWPIs respond to COS generated from various TT and DS configurations and 2) inform improved DW treatment plant design and operation to mitigate the generation and impact of NMT on human health. To implement the educational and outreach goals of this CAREER project, the Principal Investigator (PI) proposes to leverage existing resources and programs at the University of Pittsburgh to 1) Engage undergraduate and graduate students in interdisciplinary research combining public health, civil engineering, and microbiology and 2) Enhance the participation of students from underrepresented groups in STEM research.

In addition, the PI plans to design and implement new K-16 educational and outreach programs to raise awareness of the impacts of changes in the design and operational protocols of DW treatment trains on the generation of DWPIs during water disinfection.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.