| Abstract | Legionella pneumophila was grown in a model warm water system with pipes of copper (Cu), stainless steel (SS) and cross-linked polyethylene (PEX) during recirculation of tap water at 25--35 degrees C. Subsequently, domestic use of warm (37 degrees C) water was simulated using tap water with a low AOC concentration (<10 microg C/L). Two times each week the temperature of the water in the electric heaters (not in the pipes) was elevated to 70 degrees C for 30 min. ATP concentrations in the water sampled from the pipes over a 2-year period were significantly different for the pipe materials, with median values of 2.1 ng/l (Cu), 2.5 ng/l (SS) and 4.5 ng/l (PEX), respectively. Median values of the biofilm concentration were similar on Cu and SS (about 630 pg ATP/cm(2)) and 1870 pg ATP/cm(2) on PEX. Legionella multiplied in these biofilms and median values of Legionella concentrations in water were 1500 CFU/l (Cu) and about 4300 CFU/l for SS and PEX. Legionella to ATP ratios in water had median values of about 0.8 CFU/pg. Hot water flushing (70 degrees C) of the pipes on day 552, followed by 2 weeks of recirculation at 37 degrees C, caused strongly increased concentrations of ATP (up to 300 ng/l) and Legionella (>10(7)CFU/l), with about 100 CFU/pg ATP. Concentrations declined to original levels within 1 week of domestic water use, etc. Legionella concentrations in water and biofilms were at the same levels for all materials after 2 years. Hence, copper temporarily limited the growth of Legionella under the applied conditions and a rapid biomass development strongly increased the Legionella to ATP ratio. |
| Authors | Dick van der Kooij, Harm R Veenendaal, Will J H Scheffer
(Affiliation: Kiwa Water Research, Groningenhaven 7, P.O. Box 1074, 3430 BB NIEUWEGEIN, The Netherlands. dick.van.der.kooj at kiwa.nl)
|
| Journal | Water research
(Water Res)
Vol. 39
Issue 13
Pg. 2789-98
(Aug 2005)
ISSN: 0043-1354 England |
| PMID | 16019051
(Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
|
| Chemical References |
- Stainless Steel
- Adenosine Triphosphate
- Iron
- Manganese
- Copper
- Water
- Polyethylene
|
| Topics |
- Adenosine Triphosphate
(analysis)
- Biofilms
(growth & development)
- Biomass
- Colony Count, Microbial
- Copper
(analysis)
- Heat
- Iron
(analysis)
- Legionella pneumophila
(physiology)
- Manganese
(analysis)
- Polyethylene
(chemistry)
- Stainless Steel
(chemistry)
- Water
(chemistry)
- Water Microbiology
- Water Supply
|
