Current Project: Association of Pathogens with Biofilms in Drinking Water Distribution Systems


The following hypotheses will be tested: a) The physical, chemical and microbial characteristics of the indigenous biofilms grown inside drinking water distribution system (DWDS) depends on the surface chemistry and roughness of the piping/coating material; b) The attachment of pathogens to the indigenous biofilm is controlled by water quality parameters such as hardness, ionic strength, and by the presence of the extracellular polymeric substances and surface roughness of the indigenous biofilm; c) Agents that weaken the biofilm matrix (i.e. decrease cohesive strength) will enhance biofilm detachment and be more effective at removing biofilms than those that only inactivate microorganisms. The project objectives include: 1) Determine the attachment mechanisms of selected pathogens to different pipe/coating materials and to indigenous biofilms attached to the pipe walls; and 2) Determine the conditions that lead to detachment of biofilm from the pipe walls. Legionella pneumophila is selected as a model waterborne pathogen.


The variables to be tested include: pipe/coating materials (i.e., polyvinyl chloride, polyethylene, and cement), disinfectant types (i.e. chlorine vs. chloramines) and water composition (e.g., ionic strength and hardness). Experimental methods include: observation and quantification of the growth of indigenous biofilms on coupons made from different pipe materials in biofilm reactors fed with tap water; characterization of the microbial communities in these biofilms; real-time monitoring of pathogen attachment using a parallel flow chamber; testing of changes in biofilm strength and detachment resulting from disinfectants and biofilm disruptor treatments; and pathogen viability tests.

Expected Results:

Successful completion of this project will contribute to the development of an accurate assessment of public health risks related to waterborne pathogens in DWDS, and approaches for minimizing those risks. The results from this project will provide scientific data to allow sound selection of pipe material and coating material for future construction of DWDS infrastructure. Furthermore, new approaches will be developed for cleaning DWDS based on the strategy of weakening the biofilm matrix and enhancing biomass detachment. These approaches will be employed to control biofilm and pathogen proliferation in DWDS so as to minimize related adverse effects on public health.

Student researchers: Dao Janjaroen (PhD in 2013) and Yun Shen

Collaborators: Professor Wen-Tso Liu (CEE, U of I), Professor Ray Hozalski (University of Minnesota), Professor Nick Ashbolt (Formerly with USEPA, currently with University of Alberta), Professor Eberhard Morgenroth (ETH and EAWAG), and Professor Steve Boppart (ECE, U of I).


  • Janjaroen*, D., Ling, F., Monroy, G., Derlon, N., Mogenroth, E., Boppart, S.A., Liu, W.-T. and Nguyen, T.H., Roles of ionic strength and biofilm roughness on adhesion kinetics of Escherichia coli onto groundwater biofilm grown on PVC surfaces. Water Research 47(7), 2531-2542, 2013, full text.
  • Shen*, Y, Monroy, G., Derlon, N., Janjaroen*, D., Huang*, C., Ashbolt, N.J., Mogenroth, E., Boppart, S.A., Liu, W.-T. and Nguyen, T.H., Role of biofilm roughness and hydrodynamic conditions in Legionella pneumophila adhesion to and detachment from simulated drinking water biofilms. Environ. Sci. Technol., 2015, 49 (7), pp 4274–4282, full text.
  • Funded by EPA Grant Number: R834870