Influence of Plumbing Materials on Biofilm Formation and Growth of Legionella pneumophila in Potable Water Systems

Abstract

A two-stage chemostat model of a plumbing system was developed, with tap water as the sole nutrient source. The model system was populated with a naturally occurring inoculum derived from an outbreak of Legionnaires' disease and containing Legionella pneumophila along with associated bacteria and protozoa. The model system was used to develop biofilms on the surfaces of a range of eight plumbing materials under controlled, reproducible conditions. The materials varied in their abilities to support biofilm development and the growth of L. pneumophila. Elastomeric surfaces had the most abundant biofilms supporting the highest numbers of L. pneumophila CFU; this was attributed to the leaching of nutrients for bacterial growth from the materials. No direct relationship existed between total biofouling and the numbers of L. pneumophila CFU.

Development of a pilot‐scale 1 for Legionella elimination in biofilm in hot water network: heat shock treatment evaluation

“…Nowadays, several studies were conducted to evaluate the efficiency of several treatments in hot water systems and cooling towers at the laboratory-scale (Viera et al 1999;Lomander et al 2004;Codony et al 2005;Buckingham-Meyer et al 2007;Hwang et al 2007), or at pilotscale (Parent et al 1996;Norton and LeChevallier 2000;Saby et al 2005) or at larger field-scale (Flannery et al 2006;Sanli-Yurudu et al 2007). In addition, some authors studied the effect of heat shock treatment on the survival of Legionella (Rogers et al 1994;Miuetzner et al 1997;Lin et al 1998;Peiro Callizo et al 2005). However, the efficiency of treatments has not been well studied because (i) real hot water systems present several variable parameters and (ii) the installed biomass quantity is not accessible to be studied.…”

Combining chlorination and chloramination processes for the inhibition of biofilm formation in drinking surface water system models

“…The heterogeneity of bio®lm could be one possible explanation for the¯uctuations in attached viable bacterial counts. It is well known that bio®lms consist of several groups of microorganisms with different nutrient requirements, and the presence of microbial groups with different physiology can vary in the bio®lm with time (van der Kooij et al 1995;Lutterbach and de Franca 1996;Percival et al 1998).…”

“…It is well known that bio®lms protect microbes against disinfectants (Block et al 1993a;Bois et al 1997;Momba et al 1998Momba et al 1999Momba et al , 2000. The presence of complex bio®lms results in an increase of planktonic cells in the drinking water distribution system (van der Wende et al 1989) and also in the corrosion of piping materials (Beck 1995). The accumulation of micro-organisms on the surface and the formation of bio®lms depends on many factors prevailing in the water system.…”

“…Moreover, the susceptibility of bacteria in chloramine-treated water was linked to effective disinfectant residual concentrations, which could be detected up to 8 days (Momba et al 1998). A study performed by Zacheus et al (2000) showed that ozonation had no effect on bio®lm formation on PVC, PE and stainless steel coupons.…”

“…The control of bio®lms within the distribution system must involve an integrated approach using a combination of several types of action, for example, reducing the amount of organic material in the water (van der Kooij et al 1995), changing the pipe materials to those which have a reduced bio®lm-forming potential or changing the disinfection regime (LeChevallier et al 1990).…”