Effectiveness of UV Irradiation for Pathogen Inactivation in Surface Waters

EPA Grant Number: R829012
Title: Effectiveness of UV Irradiation for Pathogen Inactivation in Surface Waters
Investigators: Linden, Karl G. , Sobsey, Mark D.
Institution: Duke University , University of North Carolina at Chapel Hill
EPA Project Officer: Page, Angela
Project Period: August 20, 2001 through August 19, 2004 (Extended to August 19, 2005)
Project Amount: $524,848
RFA: Drinking Water (2000) RFA Text |  Recipients Lists
Research Category: Drinking Water , Water


UV is now recognized to be an inexpensive and relatively easy means to achieve disinfection of Cryptosporidium parvum and does not appear to produce disinfection by-products at practical doses. The germicidal effects of UV against emerging pathogens and challenges related to application of UV disinfection for filtered and unfiltered surface waters need to be assessed. The objectives of the research are to evaluate the susceptibility, repair potential, and resistance of select Contaminant Candidate List (CCL) pathogens and indicators to UV disinfection from low and medium pressure UV sources, and to elucidate the relative germicidal effective of different wavelengths of UV for these pathogens and indicators. The extent to which microbes are associated with water treatment particles typical in unfiltered systems and the effects of this particle association and other water quality parameters on UV disinfection potential will be investigated. It is hypothesized that UV will be an effective means to inactivate CCL pathogens and that with proper system design, repair/reactivation and water quality challenges found in typical treatment scenarios will not compromise effective UV treatment.


Our research approach integrates the expertise and experience of the co-investigators in environmental microbiology and UV dosimetry and disinfection process design to address these important questions and others. Specifically, numerous organisms on the US EPA Contaminant Candidate List (CCL) including bacteria (Mycobacterium spp.), viruses (adenoviruses, coxsackieviruses), and protozoans (Toxoplasma gondii) in addition to various indicator organisms will be evaluated for UV dose response to monochromatic and polychromatic UV irradiation. These CCL organisms will be evaluated to determine the relative wavelength effectiveness of UV irradiation, the potential for repair and reactivation under light and dark conditions, and the response to sequential application of UV and chlorine/chloramines. The extent to which microorganisms are associated with particles from water treatment and the effects of particle association and clumping of microorganisms on UV inactivation will be investigated, including the effect of upstream coagulation/flocculation protocols on microbe-particle association. Finally, the range of chlorine doses necessary to achieve sufficient inactivation of viruses following disinfection with UV optimized for Cryptosporidium and Giardia will be assessed to aid in design of an effective multiple disinfectant barrier.

Expected Results:

The results of the project are expected to provide a thorough understanding of UV disinfection as applied to filtered and unfiltered surface water supplies. The information generated will be useful to regulators, utility managers, and consultants to optimize application, use, and design of UV disinfection systems. Integrating the use of UV and chlorine disinfectants will likely provide protection from protozoans, viruses, and bacteria, while minimizing disinfection byproduct formation, leading toward greater protection of public health.

Publications and Presentations:

Publications have been submitted on this project: View all 25 publications for this project

Journal Articles:

Journal Articles have been submitted on this project: View all 12 journal articles for this project

Supplemental Keywords:

disinfection, environmental engineering, microbiology, drinking water., RFA, Scientific Discipline, Water, Environmental Chemistry, Health Risk Assessment, Ecological Risk Assessment, Ecology and Ecosystems, Drinking Water, Environmental Engineering, cryptosporidium parvum oocysts, pathogens, other - exposure, monitoring, CCL, chlorination, microbiological organisms, exposure and effects, disinfection byproducts (DPBs), exposure, UV treatment, Other - risk management, chlorine-based disinfection, cryptosporidium , public health, treatment, microbial risk management, water quality, DBP risk management, drinking water contaminants, drinking water treatment, Giardia, water treatment, contaminant candidate list, drinking water system, dosimetry

Progress and Final Reports:

  • 2002 Progress Report
  • 2003 Progress Report
  • 2004 Progress Report
  • Final Report