Grantee Research Project Results
2012 Progress Report: Association of Pathogens with Biofilms in Drinking Water Distribution Systems
EPA Grant Number: R834870Title: Association of Pathogens with Biofilms in Drinking Water Distribution Systems
Investigators: Nguyen, Thanh (Helen) H. , Hozalski, Raymond , Liu, Wen-Tso
Institution: University of Illinois Urbana-Champaign , University of Minnesota
EPA Project Officer: Packard, Benjamin H
Project Period: June 1, 2011 through May 28, 2016
Project Period Covered by this Report: June 1, 2012 through May 31,2013
Project Amount: $600,000
RFA: Advancing Public Health Protection through Water Infrastructure Sustainability (2009) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
1) To focus on addressing the public health risk due to waterborne pathogen contamination of the distribution system.
2) To identify the factors that influence the persistence of a model pathogen, Legionella, in multi-species biofilms grown on different pipe materials under conditions relevant to distribution systems.
3) To use molecular biology and surface chemistry tools to characterize the microbial communities and the surface properties of the biofilms, respectively.
4) To further investigate novel chemical and enzymatic treatments to weaken the biofilm to promote detachment and improved cleaning.
Progress Summary:
1) We found that adhesion of Legionella cells on clean coupon surface and 2-week biofilm surface was dependent on ionic strength, but was controlled by other mechanisms instead of ionic strength when biofilms were older than 4 weeks. Hydrophobicity was not a factor controlling freshly grown and 5-week starved Legionella cells on 8-week biofilm. Linear correlation between biofilm specific surface area and adhesion of Legionella cells on biofilms grown for 4 to 29 weeks was found, suggesting that higher adhesion on rough biofilm was due to higher available surface area.
2) Biofilms were grown with groundwater and dechlorinated tap water on PVC coupon in CDC reactors, and were subsequently disinfected with monochloramine and chlorine for 3 months. The biofilm structure was determined with optical coherent tomography (OCT) or CLSM, depending on the biofilm thickness. OCT results revealed that 12 week of exposure to monochloramine led to smoother but not thinner biofilms.
3) E. coli and Legionella adhesion on groundwater biofilm after monochloramine exposure was lower than on groundwater biofilms without monochloramine exposure, consistent with reduced biofilm roughness after exposure. Twelve weeks exposure of biofilm grown from dechlorinated tap water for 8 weeks to tap water also led to lower adhesion of environmental isolate E. coli.
4) Characterize the biofilms grown on PVC coupons using dechlorinated tap waters from Urbana, IL and Saint Paul, MN.
Future Activities:
1) Biofilms will be grown from groundwater and dechlorinated tap water on copper coupons.
2) Biofilms will be characterized with respect to structure and cohesiveness and the characteristics will be used to explain the deposition and detachment data of Legionella.
3) Detachment of Legionella from biofilm exposure to different shear rate and disinfectants will be studied. Culturability of the detached Legionella will be studied.
4) Detachment of biofilms exposed to different chemicals will be determined.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 8 publications | 4 publications in selected types | All 4 journal articles |
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Janjaroen D, Ling F, Monroy G, Derlon N, Mogenroth E, Boppart SA, Liu W-T, NguyenTH. Roles of ionic strength and biofilm roughness on adhesion kinetics of Escherichia coli onto groundwater biofilm grown on PVC surfaces. Water Research 2013;47(7):2531-2542. |
R834870 (2012) |
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Supplemental Keywords:
drinking water, pathogenProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.