Keevil (1993) that copper supported sparse microbial growth and et al., comprised a very low proportion of the population. The low colonization Legionella of copper surfaces was presumed to be due to the inhibitory effect of copper ions, either by selectively inhibiting or by inhibiting the organisms that support Legionella their growth. The most prolific biofilms were those that developed on the surface of elastomeric materials. The biofilm covered the entire elastomer surfaces after only 24 hours and contained more than 8.9x106cfu/cm2 on latex and 2.7x106cfu/cm2 on ethylene propylene rubber. The highest populations of were found on L. pneumophila latex as well (Keevil 1993). et al., Rogers (1994) found that the lowest concentration of flora was on the stainless et al., steel surface and that the latex and ethylene-propylene rubber were most heavily colonised. Of the plastic materials used, polyethylene appeared to be most heavily colonised (Rogers 1994). et al., full size hot and cold water services rigs were constructed by the Building Services Research and Information Association (BSRIA) in 1996 to evaluate the efficacy of temperature and copper and silver ionization techniques to control see Figure 1.3. Each rig replicated the water system of a small home for Legionella, the elderly. Two of the rigs were fitted with ionization water treatment from silver/copper alloy electrodes and were operating at reduced hot water temperatures; one was filled with hard water and one with soft water. The third rig relied solely upon temperature as disinfection and was filled only with hard water. The cold water system in each rig consisted of a glass reinforced plastic cistern, which served a cold water copper pipework circuit of 30m in length, which included two cold taps and one shower. The hot water system consisted of a vertical hot water storage calorifier of copper construction, which served a hot water copper pipework circuit of 40m length, which included two hot taps and one shower. Copper and glass reinforced plastic coupons were inserted at various locations in each rig. These coupons were regularly removed for biofilm and analysis. Legionella 24
Keevil et al., (1993) that copper supported sparse microbial growth and Legionella comprised a very low proportion of the population. The low colonization of copper surfaces was presumed to be due to the inhibitory effect of copper ions, either by selectively inhibiting Legionella or by inhibiting the organisms that support their growth. The most prolific biofilms were those that developed on the surface of elastomeric materials. The biofilm covered the entire elastomer surfaces after only 24 hours and contained more than 8.9x106cfu/cm2 on latex and 2.7x106cfu/cm2 on ethylene propylene rubber. The highest populations of L. pneumophila were found on latex as well (Keevil et al., 1993). Rogers et al., (1994) found that the lowest concentration of flora was on the stainless steel surface and that the latex and ethylene-propylene rubber were most heavily colonised. Of the plastic materials used, polyethylene appeared to be most heavily colonised (Rogers et al., 1994). full size hot and cold water services rigs were constructed by the Building Services Research and Information Association (BSRIA) in 1996 to evaluate the efficacy of temperature and copper and silver ionization techniques to control Legionella, see Figure 1.3. Each rig replicated the water system of a small home for the elderly. Two of the rigs were fitted with ionization water treatment from silver/copper alloy electrodes and were operating at reduced hot water temperatures; one was filled with hard water and one with soft water. The third rig relied solely upon temperature as disinfection and was filled only with hard water. The cold water system in each rig consisted of a glass reinforced plastic cistern, which served a cold water copper pipework circuit of 30m in length, which included two cold taps and one shower. The hot water system consisted of a vertical hot water storage calorifier of copper construction, which served a hot water copper pipework circuit of 40m length, which included two hot taps and one shower. Copper and glass reinforced plastic coupons were inserted at various locations in each rig. These coupons were regularly removed for biofilm and Legionella analysis. 24
Birgitta-Bedford-Thesis-2012.docx